Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso...
[~shefty/rdma-dev.git] / fs / ext4 / inode.c
1 /*
2  *  linux/fs/ext4/inode.c
3  *
4  * Copyright (C) 1992, 1993, 1994, 1995
5  * Remy Card (card@masi.ibp.fr)
6  * Laboratoire MASI - Institut Blaise Pascal
7  * Universite Pierre et Marie Curie (Paris VI)
8  *
9  *  from
10  *
11  *  linux/fs/minix/inode.c
12  *
13  *  Copyright (C) 1991, 1992  Linus Torvalds
14  *
15  *  64-bit file support on 64-bit platforms by Jakub Jelinek
16  *      (jj@sunsite.ms.mff.cuni.cz)
17  *
18  *  Assorted race fixes, rewrite of ext4_get_block() by Al Viro, 2000
19  */
20
21 #include <linux/fs.h>
22 #include <linux/time.h>
23 #include <linux/jbd2.h>
24 #include <linux/highuid.h>
25 #include <linux/pagemap.h>
26 #include <linux/quotaops.h>
27 #include <linux/string.h>
28 #include <linux/buffer_head.h>
29 #include <linux/writeback.h>
30 #include <linux/pagevec.h>
31 #include <linux/mpage.h>
32 #include <linux/namei.h>
33 #include <linux/uio.h>
34 #include <linux/bio.h>
35 #include <linux/workqueue.h>
36 #include <linux/kernel.h>
37 #include <linux/printk.h>
38 #include <linux/slab.h>
39 #include <linux/ratelimit.h>
40
41 #include "ext4_jbd2.h"
42 #include "xattr.h"
43 #include "acl.h"
44 #include "truncate.h"
45
46 #include <trace/events/ext4.h>
47
48 #define MPAGE_DA_EXTENT_TAIL 0x01
49
50 static __u32 ext4_inode_csum(struct inode *inode, struct ext4_inode *raw,
51                               struct ext4_inode_info *ei)
52 {
53         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
54         __u16 csum_lo;
55         __u16 csum_hi = 0;
56         __u32 csum;
57
58         csum_lo = raw->i_checksum_lo;
59         raw->i_checksum_lo = 0;
60         if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
61             EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi)) {
62                 csum_hi = raw->i_checksum_hi;
63                 raw->i_checksum_hi = 0;
64         }
65
66         csum = ext4_chksum(sbi, ei->i_csum_seed, (__u8 *)raw,
67                            EXT4_INODE_SIZE(inode->i_sb));
68
69         raw->i_checksum_lo = csum_lo;
70         if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
71             EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi))
72                 raw->i_checksum_hi = csum_hi;
73
74         return csum;
75 }
76
77 static int ext4_inode_csum_verify(struct inode *inode, struct ext4_inode *raw,
78                                   struct ext4_inode_info *ei)
79 {
80         __u32 provided, calculated;
81
82         if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
83             cpu_to_le32(EXT4_OS_LINUX) ||
84             !EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,
85                 EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
86                 return 1;
87
88         provided = le16_to_cpu(raw->i_checksum_lo);
89         calculated = ext4_inode_csum(inode, raw, ei);
90         if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
91             EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi))
92                 provided |= ((__u32)le16_to_cpu(raw->i_checksum_hi)) << 16;
93         else
94                 calculated &= 0xFFFF;
95
96         return provided == calculated;
97 }
98
99 static void ext4_inode_csum_set(struct inode *inode, struct ext4_inode *raw,
100                                 struct ext4_inode_info *ei)
101 {
102         __u32 csum;
103
104         if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
105             cpu_to_le32(EXT4_OS_LINUX) ||
106             !EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,
107                 EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
108                 return;
109
110         csum = ext4_inode_csum(inode, raw, ei);
111         raw->i_checksum_lo = cpu_to_le16(csum & 0xFFFF);
112         if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
113             EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi))
114                 raw->i_checksum_hi = cpu_to_le16(csum >> 16);
115 }
116
117 static inline int ext4_begin_ordered_truncate(struct inode *inode,
118                                               loff_t new_size)
119 {
120         trace_ext4_begin_ordered_truncate(inode, new_size);
121         /*
122          * If jinode is zero, then we never opened the file for
123          * writing, so there's no need to call
124          * jbd2_journal_begin_ordered_truncate() since there's no
125          * outstanding writes we need to flush.
126          */
127         if (!EXT4_I(inode)->jinode)
128                 return 0;
129         return jbd2_journal_begin_ordered_truncate(EXT4_JOURNAL(inode),
130                                                    EXT4_I(inode)->jinode,
131                                                    new_size);
132 }
133
134 static void ext4_invalidatepage(struct page *page, unsigned long offset);
135 static int __ext4_journalled_writepage(struct page *page, unsigned int len);
136 static int ext4_bh_delay_or_unwritten(handle_t *handle, struct buffer_head *bh);
137 static int ext4_discard_partial_page_buffers_no_lock(handle_t *handle,
138                 struct inode *inode, struct page *page, loff_t from,
139                 loff_t length, int flags);
140
141 /*
142  * Test whether an inode is a fast symlink.
143  */
144 static int ext4_inode_is_fast_symlink(struct inode *inode)
145 {
146         int ea_blocks = EXT4_I(inode)->i_file_acl ?
147                 (inode->i_sb->s_blocksize >> 9) : 0;
148
149         return (S_ISLNK(inode->i_mode) && inode->i_blocks - ea_blocks == 0);
150 }
151
152 /*
153  * Restart the transaction associated with *handle.  This does a commit,
154  * so before we call here everything must be consistently dirtied against
155  * this transaction.
156  */
157 int ext4_truncate_restart_trans(handle_t *handle, struct inode *inode,
158                                  int nblocks)
159 {
160         int ret;
161
162         /*
163          * Drop i_data_sem to avoid deadlock with ext4_map_blocks.  At this
164          * moment, get_block can be called only for blocks inside i_size since
165          * page cache has been already dropped and writes are blocked by
166          * i_mutex. So we can safely drop the i_data_sem here.
167          */
168         BUG_ON(EXT4_JOURNAL(inode) == NULL);
169         jbd_debug(2, "restarting handle %p\n", handle);
170         up_write(&EXT4_I(inode)->i_data_sem);
171         ret = ext4_journal_restart(handle, nblocks);
172         down_write(&EXT4_I(inode)->i_data_sem);
173         ext4_discard_preallocations(inode);
174
175         return ret;
176 }
177
178 /*
179  * Called at the last iput() if i_nlink is zero.
180  */
181 void ext4_evict_inode(struct inode *inode)
182 {
183         handle_t *handle;
184         int err;
185
186         trace_ext4_evict_inode(inode);
187
188         ext4_ioend_wait(inode);
189
190         if (inode->i_nlink) {
191                 /*
192                  * When journalling data dirty buffers are tracked only in the
193                  * journal. So although mm thinks everything is clean and
194                  * ready for reaping the inode might still have some pages to
195                  * write in the running transaction or waiting to be
196                  * checkpointed. Thus calling jbd2_journal_invalidatepage()
197                  * (via truncate_inode_pages()) to discard these buffers can
198                  * cause data loss. Also even if we did not discard these
199                  * buffers, we would have no way to find them after the inode
200                  * is reaped and thus user could see stale data if he tries to
201                  * read them before the transaction is checkpointed. So be
202                  * careful and force everything to disk here... We use
203                  * ei->i_datasync_tid to store the newest transaction
204                  * containing inode's data.
205                  *
206                  * Note that directories do not have this problem because they
207                  * don't use page cache.
208                  */
209                 if (ext4_should_journal_data(inode) &&
210                     (S_ISLNK(inode->i_mode) || S_ISREG(inode->i_mode))) {
211                         journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
212                         tid_t commit_tid = EXT4_I(inode)->i_datasync_tid;
213
214                         jbd2_log_start_commit(journal, commit_tid);
215                         jbd2_log_wait_commit(journal, commit_tid);
216                         filemap_write_and_wait(&inode->i_data);
217                 }
218                 truncate_inode_pages(&inode->i_data, 0);
219                 goto no_delete;
220         }
221
222         if (!is_bad_inode(inode))
223                 dquot_initialize(inode);
224
225         if (ext4_should_order_data(inode))
226                 ext4_begin_ordered_truncate(inode, 0);
227         truncate_inode_pages(&inode->i_data, 0);
228
229         if (is_bad_inode(inode))
230                 goto no_delete;
231
232         /*
233          * Protect us against freezing - iput() caller didn't have to have any
234          * protection against it
235          */
236         sb_start_intwrite(inode->i_sb);
237         handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE,
238                                     ext4_blocks_for_truncate(inode)+3);
239         if (IS_ERR(handle)) {
240                 ext4_std_error(inode->i_sb, PTR_ERR(handle));
241                 /*
242                  * If we're going to skip the normal cleanup, we still need to
243                  * make sure that the in-core orphan linked list is properly
244                  * cleaned up.
245                  */
246                 ext4_orphan_del(NULL, inode);
247                 sb_end_intwrite(inode->i_sb);
248                 goto no_delete;
249         }
250
251         if (IS_SYNC(inode))
252                 ext4_handle_sync(handle);
253         inode->i_size = 0;
254         err = ext4_mark_inode_dirty(handle, inode);
255         if (err) {
256                 ext4_warning(inode->i_sb,
257                              "couldn't mark inode dirty (err %d)", err);
258                 goto stop_handle;
259         }
260         if (inode->i_blocks)
261                 ext4_truncate(inode);
262
263         /*
264          * ext4_ext_truncate() doesn't reserve any slop when it
265          * restarts journal transactions; therefore there may not be
266          * enough credits left in the handle to remove the inode from
267          * the orphan list and set the dtime field.
268          */
269         if (!ext4_handle_has_enough_credits(handle, 3)) {
270                 err = ext4_journal_extend(handle, 3);
271                 if (err > 0)
272                         err = ext4_journal_restart(handle, 3);
273                 if (err != 0) {
274                         ext4_warning(inode->i_sb,
275                                      "couldn't extend journal (err %d)", err);
276                 stop_handle:
277                         ext4_journal_stop(handle);
278                         ext4_orphan_del(NULL, inode);
279                         sb_end_intwrite(inode->i_sb);
280                         goto no_delete;
281                 }
282         }
283
284         /*
285          * Kill off the orphan record which ext4_truncate created.
286          * AKPM: I think this can be inside the above `if'.
287          * Note that ext4_orphan_del() has to be able to cope with the
288          * deletion of a non-existent orphan - this is because we don't
289          * know if ext4_truncate() actually created an orphan record.
290          * (Well, we could do this if we need to, but heck - it works)
291          */
292         ext4_orphan_del(handle, inode);
293         EXT4_I(inode)->i_dtime  = get_seconds();
294
295         /*
296          * One subtle ordering requirement: if anything has gone wrong
297          * (transaction abort, IO errors, whatever), then we can still
298          * do these next steps (the fs will already have been marked as
299          * having errors), but we can't free the inode if the mark_dirty
300          * fails.
301          */
302         if (ext4_mark_inode_dirty(handle, inode))
303                 /* If that failed, just do the required in-core inode clear. */
304                 ext4_clear_inode(inode);
305         else
306                 ext4_free_inode(handle, inode);
307         ext4_journal_stop(handle);
308         sb_end_intwrite(inode->i_sb);
309         return;
310 no_delete:
311         ext4_clear_inode(inode);        /* We must guarantee clearing of inode... */
312 }
313
314 #ifdef CONFIG_QUOTA
315 qsize_t *ext4_get_reserved_space(struct inode *inode)
316 {
317         return &EXT4_I(inode)->i_reserved_quota;
318 }
319 #endif
320
321 /*
322  * Calculate the number of metadata blocks need to reserve
323  * to allocate a block located at @lblock
324  */
325 static int ext4_calc_metadata_amount(struct inode *inode, ext4_lblk_t lblock)
326 {
327         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
328                 return ext4_ext_calc_metadata_amount(inode, lblock);
329
330         return ext4_ind_calc_metadata_amount(inode, lblock);
331 }
332
333 /*
334  * Called with i_data_sem down, which is important since we can call
335  * ext4_discard_preallocations() from here.
336  */
337 void ext4_da_update_reserve_space(struct inode *inode,
338                                         int used, int quota_claim)
339 {
340         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
341         struct ext4_inode_info *ei = EXT4_I(inode);
342
343         spin_lock(&ei->i_block_reservation_lock);
344         trace_ext4_da_update_reserve_space(inode, used, quota_claim);
345         if (unlikely(used > ei->i_reserved_data_blocks)) {
346                 ext4_warning(inode->i_sb, "%s: ino %lu, used %d "
347                          "with only %d reserved data blocks",
348                          __func__, inode->i_ino, used,
349                          ei->i_reserved_data_blocks);
350                 WARN_ON(1);
351                 used = ei->i_reserved_data_blocks;
352         }
353
354         if (unlikely(ei->i_allocated_meta_blocks > ei->i_reserved_meta_blocks)) {
355                 ext4_warning(inode->i_sb, "ino %lu, allocated %d "
356                         "with only %d reserved metadata blocks "
357                         "(releasing %d blocks with reserved %d data blocks)",
358                         inode->i_ino, ei->i_allocated_meta_blocks,
359                              ei->i_reserved_meta_blocks, used,
360                              ei->i_reserved_data_blocks);
361                 WARN_ON(1);
362                 ei->i_allocated_meta_blocks = ei->i_reserved_meta_blocks;
363         }
364
365         /* Update per-inode reservations */
366         ei->i_reserved_data_blocks -= used;
367         ei->i_reserved_meta_blocks -= ei->i_allocated_meta_blocks;
368         percpu_counter_sub(&sbi->s_dirtyclusters_counter,
369                            used + ei->i_allocated_meta_blocks);
370         ei->i_allocated_meta_blocks = 0;
371
372         if (ei->i_reserved_data_blocks == 0) {
373                 /*
374                  * We can release all of the reserved metadata blocks
375                  * only when we have written all of the delayed
376                  * allocation blocks.
377                  */
378                 percpu_counter_sub(&sbi->s_dirtyclusters_counter,
379                                    ei->i_reserved_meta_blocks);
380                 ei->i_reserved_meta_blocks = 0;
381                 ei->i_da_metadata_calc_len = 0;
382         }
383         spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
384
385         /* Update quota subsystem for data blocks */
386         if (quota_claim)
387                 dquot_claim_block(inode, EXT4_C2B(sbi, used));
388         else {
389                 /*
390                  * We did fallocate with an offset that is already delayed
391                  * allocated. So on delayed allocated writeback we should
392                  * not re-claim the quota for fallocated blocks.
393                  */
394                 dquot_release_reservation_block(inode, EXT4_C2B(sbi, used));
395         }
396
397         /*
398          * If we have done all the pending block allocations and if
399          * there aren't any writers on the inode, we can discard the
400          * inode's preallocations.
401          */
402         if ((ei->i_reserved_data_blocks == 0) &&
403             (atomic_read(&inode->i_writecount) == 0))
404                 ext4_discard_preallocations(inode);
405 }
406
407 static int __check_block_validity(struct inode *inode, const char *func,
408                                 unsigned int line,
409                                 struct ext4_map_blocks *map)
410 {
411         if (!ext4_data_block_valid(EXT4_SB(inode->i_sb), map->m_pblk,
412                                    map->m_len)) {
413                 ext4_error_inode(inode, func, line, map->m_pblk,
414                                  "lblock %lu mapped to illegal pblock "
415                                  "(length %d)", (unsigned long) map->m_lblk,
416                                  map->m_len);
417                 return -EIO;
418         }
419         return 0;
420 }
421
422 #define check_block_validity(inode, map)        \
423         __check_block_validity((inode), __func__, __LINE__, (map))
424
425 /*
426  * Return the number of contiguous dirty pages in a given inode
427  * starting at page frame idx.
428  */
429 static pgoff_t ext4_num_dirty_pages(struct inode *inode, pgoff_t idx,
430                                     unsigned int max_pages)
431 {
432         struct address_space *mapping = inode->i_mapping;
433         pgoff_t index;
434         struct pagevec pvec;
435         pgoff_t num = 0;
436         int i, nr_pages, done = 0;
437
438         if (max_pages == 0)
439                 return 0;
440         pagevec_init(&pvec, 0);
441         while (!done) {
442                 index = idx;
443                 nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
444                                               PAGECACHE_TAG_DIRTY,
445                                               (pgoff_t)PAGEVEC_SIZE);
446                 if (nr_pages == 0)
447                         break;
448                 for (i = 0; i < nr_pages; i++) {
449                         struct page *page = pvec.pages[i];
450                         struct buffer_head *bh, *head;
451
452                         lock_page(page);
453                         if (unlikely(page->mapping != mapping) ||
454                             !PageDirty(page) ||
455                             PageWriteback(page) ||
456                             page->index != idx) {
457                                 done = 1;
458                                 unlock_page(page);
459                                 break;
460                         }
461                         if (page_has_buffers(page)) {
462                                 bh = head = page_buffers(page);
463                                 do {
464                                         if (!buffer_delay(bh) &&
465                                             !buffer_unwritten(bh))
466                                                 done = 1;
467                                         bh = bh->b_this_page;
468                                 } while (!done && (bh != head));
469                         }
470                         unlock_page(page);
471                         if (done)
472                                 break;
473                         idx++;
474                         num++;
475                         if (num >= max_pages) {
476                                 done = 1;
477                                 break;
478                         }
479                 }
480                 pagevec_release(&pvec);
481         }
482         return num;
483 }
484
485 /*
486  * The ext4_map_blocks() function tries to look up the requested blocks,
487  * and returns if the blocks are already mapped.
488  *
489  * Otherwise it takes the write lock of the i_data_sem and allocate blocks
490  * and store the allocated blocks in the result buffer head and mark it
491  * mapped.
492  *
493  * If file type is extents based, it will call ext4_ext_map_blocks(),
494  * Otherwise, call with ext4_ind_map_blocks() to handle indirect mapping
495  * based files
496  *
497  * On success, it returns the number of blocks being mapped or allocate.
498  * if create==0 and the blocks are pre-allocated and uninitialized block,
499  * the result buffer head is unmapped. If the create ==1, it will make sure
500  * the buffer head is mapped.
501  *
502  * It returns 0 if plain look up failed (blocks have not been allocated), in
503  * that case, buffer head is unmapped
504  *
505  * It returns the error in case of allocation failure.
506  */
507 int ext4_map_blocks(handle_t *handle, struct inode *inode,
508                     struct ext4_map_blocks *map, int flags)
509 {
510         struct extent_status es;
511         int retval;
512
513         map->m_flags = 0;
514         ext_debug("ext4_map_blocks(): inode %lu, flag %d, max_blocks %u,"
515                   "logical block %lu\n", inode->i_ino, flags, map->m_len,
516                   (unsigned long) map->m_lblk);
517
518         /* Lookup extent status tree firstly */
519         if (ext4_es_lookup_extent(inode, map->m_lblk, &es)) {
520                 if (ext4_es_is_written(&es) || ext4_es_is_unwritten(&es)) {
521                         map->m_pblk = ext4_es_pblock(&es) +
522                                         map->m_lblk - es.es_lblk;
523                         map->m_flags |= ext4_es_is_written(&es) ?
524                                         EXT4_MAP_MAPPED : EXT4_MAP_UNWRITTEN;
525                         retval = es.es_len - (map->m_lblk - es.es_lblk);
526                         if (retval > map->m_len)
527                                 retval = map->m_len;
528                         map->m_len = retval;
529                 } else if (ext4_es_is_delayed(&es) || ext4_es_is_hole(&es)) {
530                         retval = 0;
531                 } else {
532                         BUG_ON(1);
533                 }
534                 goto found;
535         }
536
537         /*
538          * Try to see if we can get the block without requesting a new
539          * file system block.
540          */
541         if (!(flags & EXT4_GET_BLOCKS_NO_LOCK))
542                 down_read((&EXT4_I(inode)->i_data_sem));
543         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
544                 retval = ext4_ext_map_blocks(handle, inode, map, flags &
545                                              EXT4_GET_BLOCKS_KEEP_SIZE);
546         } else {
547                 retval = ext4_ind_map_blocks(handle, inode, map, flags &
548                                              EXT4_GET_BLOCKS_KEEP_SIZE);
549         }
550         if (retval > 0) {
551                 int ret;
552                 unsigned long long status;
553
554                 status = map->m_flags & EXT4_MAP_UNWRITTEN ?
555                                 EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
556                 if (!(flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) &&
557                     ext4_find_delalloc_range(inode, map->m_lblk,
558                                              map->m_lblk + map->m_len - 1))
559                         status |= EXTENT_STATUS_DELAYED;
560                 ret = ext4_es_insert_extent(inode, map->m_lblk,
561                                             map->m_len, map->m_pblk, status);
562                 if (ret < 0)
563                         retval = ret;
564         }
565         if (!(flags & EXT4_GET_BLOCKS_NO_LOCK))
566                 up_read((&EXT4_I(inode)->i_data_sem));
567
568 found:
569         if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
570                 int ret = check_block_validity(inode, map);
571                 if (ret != 0)
572                         return ret;
573         }
574
575         /* If it is only a block(s) look up */
576         if ((flags & EXT4_GET_BLOCKS_CREATE) == 0)
577                 return retval;
578
579         /*
580          * Returns if the blocks have already allocated
581          *
582          * Note that if blocks have been preallocated
583          * ext4_ext_get_block() returns the create = 0
584          * with buffer head unmapped.
585          */
586         if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED)
587                 return retval;
588
589         /*
590          * Here we clear m_flags because after allocating an new extent,
591          * it will be set again.
592          */
593         map->m_flags &= ~EXT4_MAP_FLAGS;
594
595         /*
596          * New blocks allocate and/or writing to uninitialized extent
597          * will possibly result in updating i_data, so we take
598          * the write lock of i_data_sem, and call get_blocks()
599          * with create == 1 flag.
600          */
601         down_write((&EXT4_I(inode)->i_data_sem));
602
603         /*
604          * if the caller is from delayed allocation writeout path
605          * we have already reserved fs blocks for allocation
606          * let the underlying get_block() function know to
607          * avoid double accounting
608          */
609         if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
610                 ext4_set_inode_state(inode, EXT4_STATE_DELALLOC_RESERVED);
611         /*
612          * We need to check for EXT4 here because migrate
613          * could have changed the inode type in between
614          */
615         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
616                 retval = ext4_ext_map_blocks(handle, inode, map, flags);
617         } else {
618                 retval = ext4_ind_map_blocks(handle, inode, map, flags);
619
620                 if (retval > 0 && map->m_flags & EXT4_MAP_NEW) {
621                         /*
622                          * We allocated new blocks which will result in
623                          * i_data's format changing.  Force the migrate
624                          * to fail by clearing migrate flags
625                          */
626                         ext4_clear_inode_state(inode, EXT4_STATE_EXT_MIGRATE);
627                 }
628
629                 /*
630                  * Update reserved blocks/metadata blocks after successful
631                  * block allocation which had been deferred till now. We don't
632                  * support fallocate for non extent files. So we can update
633                  * reserve space here.
634                  */
635                 if ((retval > 0) &&
636                         (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE))
637                         ext4_da_update_reserve_space(inode, retval, 1);
638         }
639         if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
640                 ext4_clear_inode_state(inode, EXT4_STATE_DELALLOC_RESERVED);
641
642         if (retval > 0) {
643                 int ret;
644                 unsigned long long status;
645
646                 status = map->m_flags & EXT4_MAP_UNWRITTEN ?
647                                 EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
648                 if (!(flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) &&
649                     ext4_find_delalloc_range(inode, map->m_lblk,
650                                              map->m_lblk + map->m_len - 1))
651                         status |= EXTENT_STATUS_DELAYED;
652                 ret = ext4_es_insert_extent(inode, map->m_lblk, map->m_len,
653                                             map->m_pblk, status);
654                 if (ret < 0)
655                         retval = ret;
656         }
657
658         up_write((&EXT4_I(inode)->i_data_sem));
659         if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
660                 int ret = check_block_validity(inode, map);
661                 if (ret != 0)
662                         return ret;
663         }
664         return retval;
665 }
666
667 /* Maximum number of blocks we map for direct IO at once. */
668 #define DIO_MAX_BLOCKS 4096
669
670 static int _ext4_get_block(struct inode *inode, sector_t iblock,
671                            struct buffer_head *bh, int flags)
672 {
673         handle_t *handle = ext4_journal_current_handle();
674         struct ext4_map_blocks map;
675         int ret = 0, started = 0;
676         int dio_credits;
677
678         if (ext4_has_inline_data(inode))
679                 return -ERANGE;
680
681         map.m_lblk = iblock;
682         map.m_len = bh->b_size >> inode->i_blkbits;
683
684         if (flags && !(flags & EXT4_GET_BLOCKS_NO_LOCK) && !handle) {
685                 /* Direct IO write... */
686                 if (map.m_len > DIO_MAX_BLOCKS)
687                         map.m_len = DIO_MAX_BLOCKS;
688                 dio_credits = ext4_chunk_trans_blocks(inode, map.m_len);
689                 handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS,
690                                             dio_credits);
691                 if (IS_ERR(handle)) {
692                         ret = PTR_ERR(handle);
693                         return ret;
694                 }
695                 started = 1;
696         }
697
698         ret = ext4_map_blocks(handle, inode, &map, flags);
699         if (ret > 0) {
700                 map_bh(bh, inode->i_sb, map.m_pblk);
701                 bh->b_state = (bh->b_state & ~EXT4_MAP_FLAGS) | map.m_flags;
702                 bh->b_size = inode->i_sb->s_blocksize * map.m_len;
703                 ret = 0;
704         }
705         if (started)
706                 ext4_journal_stop(handle);
707         return ret;
708 }
709
710 int ext4_get_block(struct inode *inode, sector_t iblock,
711                    struct buffer_head *bh, int create)
712 {
713         return _ext4_get_block(inode, iblock, bh,
714                                create ? EXT4_GET_BLOCKS_CREATE : 0);
715 }
716
717 /*
718  * `handle' can be NULL if create is zero
719  */
720 struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode,
721                                 ext4_lblk_t block, int create, int *errp)
722 {
723         struct ext4_map_blocks map;
724         struct buffer_head *bh;
725         int fatal = 0, err;
726
727         J_ASSERT(handle != NULL || create == 0);
728
729         map.m_lblk = block;
730         map.m_len = 1;
731         err = ext4_map_blocks(handle, inode, &map,
732                               create ? EXT4_GET_BLOCKS_CREATE : 0);
733
734         /* ensure we send some value back into *errp */
735         *errp = 0;
736
737         if (create && err == 0)
738                 err = -ENOSPC;  /* should never happen */
739         if (err < 0)
740                 *errp = err;
741         if (err <= 0)
742                 return NULL;
743
744         bh = sb_getblk(inode->i_sb, map.m_pblk);
745         if (unlikely(!bh)) {
746                 *errp = -ENOMEM;
747                 return NULL;
748         }
749         if (map.m_flags & EXT4_MAP_NEW) {
750                 J_ASSERT(create != 0);
751                 J_ASSERT(handle != NULL);
752
753                 /*
754                  * Now that we do not always journal data, we should
755                  * keep in mind whether this should always journal the
756                  * new buffer as metadata.  For now, regular file
757                  * writes use ext4_get_block instead, so it's not a
758                  * problem.
759                  */
760                 lock_buffer(bh);
761                 BUFFER_TRACE(bh, "call get_create_access");
762                 fatal = ext4_journal_get_create_access(handle, bh);
763                 if (!fatal && !buffer_uptodate(bh)) {
764                         memset(bh->b_data, 0, inode->i_sb->s_blocksize);
765                         set_buffer_uptodate(bh);
766                 }
767                 unlock_buffer(bh);
768                 BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
769                 err = ext4_handle_dirty_metadata(handle, inode, bh);
770                 if (!fatal)
771                         fatal = err;
772         } else {
773                 BUFFER_TRACE(bh, "not a new buffer");
774         }
775         if (fatal) {
776                 *errp = fatal;
777                 brelse(bh);
778                 bh = NULL;
779         }
780         return bh;
781 }
782
783 struct buffer_head *ext4_bread(handle_t *handle, struct inode *inode,
784                                ext4_lblk_t block, int create, int *err)
785 {
786         struct buffer_head *bh;
787
788         bh = ext4_getblk(handle, inode, block, create, err);
789         if (!bh)
790                 return bh;
791         if (buffer_uptodate(bh))
792                 return bh;
793         ll_rw_block(READ | REQ_META | REQ_PRIO, 1, &bh);
794         wait_on_buffer(bh);
795         if (buffer_uptodate(bh))
796                 return bh;
797         put_bh(bh);
798         *err = -EIO;
799         return NULL;
800 }
801
802 int ext4_walk_page_buffers(handle_t *handle,
803                            struct buffer_head *head,
804                            unsigned from,
805                            unsigned to,
806                            int *partial,
807                            int (*fn)(handle_t *handle,
808                                      struct buffer_head *bh))
809 {
810         struct buffer_head *bh;
811         unsigned block_start, block_end;
812         unsigned blocksize = head->b_size;
813         int err, ret = 0;
814         struct buffer_head *next;
815
816         for (bh = head, block_start = 0;
817              ret == 0 && (bh != head || !block_start);
818              block_start = block_end, bh = next) {
819                 next = bh->b_this_page;
820                 block_end = block_start + blocksize;
821                 if (block_end <= from || block_start >= to) {
822                         if (partial && !buffer_uptodate(bh))
823                                 *partial = 1;
824                         continue;
825                 }
826                 err = (*fn)(handle, bh);
827                 if (!ret)
828                         ret = err;
829         }
830         return ret;
831 }
832
833 /*
834  * To preserve ordering, it is essential that the hole instantiation and
835  * the data write be encapsulated in a single transaction.  We cannot
836  * close off a transaction and start a new one between the ext4_get_block()
837  * and the commit_write().  So doing the jbd2_journal_start at the start of
838  * prepare_write() is the right place.
839  *
840  * Also, this function can nest inside ext4_writepage().  In that case, we
841  * *know* that ext4_writepage() has generated enough buffer credits to do the
842  * whole page.  So we won't block on the journal in that case, which is good,
843  * because the caller may be PF_MEMALLOC.
844  *
845  * By accident, ext4 can be reentered when a transaction is open via
846  * quota file writes.  If we were to commit the transaction while thus
847  * reentered, there can be a deadlock - we would be holding a quota
848  * lock, and the commit would never complete if another thread had a
849  * transaction open and was blocking on the quota lock - a ranking
850  * violation.
851  *
852  * So what we do is to rely on the fact that jbd2_journal_stop/journal_start
853  * will _not_ run commit under these circumstances because handle->h_ref
854  * is elevated.  We'll still have enough credits for the tiny quotafile
855  * write.
856  */
857 int do_journal_get_write_access(handle_t *handle,
858                                 struct buffer_head *bh)
859 {
860         int dirty = buffer_dirty(bh);
861         int ret;
862
863         if (!buffer_mapped(bh) || buffer_freed(bh))
864                 return 0;
865         /*
866          * __block_write_begin() could have dirtied some buffers. Clean
867          * the dirty bit as jbd2_journal_get_write_access() could complain
868          * otherwise about fs integrity issues. Setting of the dirty bit
869          * by __block_write_begin() isn't a real problem here as we clear
870          * the bit before releasing a page lock and thus writeback cannot
871          * ever write the buffer.
872          */
873         if (dirty)
874                 clear_buffer_dirty(bh);
875         ret = ext4_journal_get_write_access(handle, bh);
876         if (!ret && dirty)
877                 ret = ext4_handle_dirty_metadata(handle, NULL, bh);
878         return ret;
879 }
880
881 static int ext4_get_block_write_nolock(struct inode *inode, sector_t iblock,
882                    struct buffer_head *bh_result, int create);
883 static int ext4_write_begin(struct file *file, struct address_space *mapping,
884                             loff_t pos, unsigned len, unsigned flags,
885                             struct page **pagep, void **fsdata)
886 {
887         struct inode *inode = mapping->host;
888         int ret, needed_blocks;
889         handle_t *handle;
890         int retries = 0;
891         struct page *page;
892         pgoff_t index;
893         unsigned from, to;
894
895         trace_ext4_write_begin(inode, pos, len, flags);
896         /*
897          * Reserve one block more for addition to orphan list in case
898          * we allocate blocks but write fails for some reason
899          */
900         needed_blocks = ext4_writepage_trans_blocks(inode) + 1;
901         index = pos >> PAGE_CACHE_SHIFT;
902         from = pos & (PAGE_CACHE_SIZE - 1);
903         to = from + len;
904
905         if (ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA)) {
906                 ret = ext4_try_to_write_inline_data(mapping, inode, pos, len,
907                                                     flags, pagep);
908                 if (ret < 0)
909                         return ret;
910                 if (ret == 1)
911                         return 0;
912         }
913
914         /*
915          * grab_cache_page_write_begin() can take a long time if the
916          * system is thrashing due to memory pressure, or if the page
917          * is being written back.  So grab it first before we start
918          * the transaction handle.  This also allows us to allocate
919          * the page (if needed) without using GFP_NOFS.
920          */
921 retry_grab:
922         page = grab_cache_page_write_begin(mapping, index, flags);
923         if (!page)
924                 return -ENOMEM;
925         unlock_page(page);
926
927 retry_journal:
928         handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE, needed_blocks);
929         if (IS_ERR(handle)) {
930                 page_cache_release(page);
931                 return PTR_ERR(handle);
932         }
933
934         lock_page(page);
935         if (page->mapping != mapping) {
936                 /* The page got truncated from under us */
937                 unlock_page(page);
938                 page_cache_release(page);
939                 ext4_journal_stop(handle);
940                 goto retry_grab;
941         }
942         wait_on_page_writeback(page);
943
944         if (ext4_should_dioread_nolock(inode))
945                 ret = __block_write_begin(page, pos, len, ext4_get_block_write);
946         else
947                 ret = __block_write_begin(page, pos, len, ext4_get_block);
948
949         if (!ret && ext4_should_journal_data(inode)) {
950                 ret = ext4_walk_page_buffers(handle, page_buffers(page),
951                                              from, to, NULL,
952                                              do_journal_get_write_access);
953         }
954
955         if (ret) {
956                 unlock_page(page);
957                 /*
958                  * __block_write_begin may have instantiated a few blocks
959                  * outside i_size.  Trim these off again. Don't need
960                  * i_size_read because we hold i_mutex.
961                  *
962                  * Add inode to orphan list in case we crash before
963                  * truncate finishes
964                  */
965                 if (pos + len > inode->i_size && ext4_can_truncate(inode))
966                         ext4_orphan_add(handle, inode);
967
968                 ext4_journal_stop(handle);
969                 if (pos + len > inode->i_size) {
970                         ext4_truncate_failed_write(inode);
971                         /*
972                          * If truncate failed early the inode might
973                          * still be on the orphan list; we need to
974                          * make sure the inode is removed from the
975                          * orphan list in that case.
976                          */
977                         if (inode->i_nlink)
978                                 ext4_orphan_del(NULL, inode);
979                 }
980
981                 if (ret == -ENOSPC &&
982                     ext4_should_retry_alloc(inode->i_sb, &retries))
983                         goto retry_journal;
984                 page_cache_release(page);
985                 return ret;
986         }
987         *pagep = page;
988         return ret;
989 }
990
991 /* For write_end() in data=journal mode */
992 static int write_end_fn(handle_t *handle, struct buffer_head *bh)
993 {
994         if (!buffer_mapped(bh) || buffer_freed(bh))
995                 return 0;
996         set_buffer_uptodate(bh);
997         return ext4_handle_dirty_metadata(handle, NULL, bh);
998 }
999
1000 static int ext4_generic_write_end(struct file *file,
1001                                   struct address_space *mapping,
1002                                   loff_t pos, unsigned len, unsigned copied,
1003                                   struct page *page, void *fsdata)
1004 {
1005         int i_size_changed = 0;
1006         struct inode *inode = mapping->host;
1007         handle_t *handle = ext4_journal_current_handle();
1008
1009         if (ext4_has_inline_data(inode))
1010                 copied = ext4_write_inline_data_end(inode, pos, len,
1011                                                     copied, page);
1012         else
1013                 copied = block_write_end(file, mapping, pos,
1014                                          len, copied, page, fsdata);
1015
1016         /*
1017          * No need to use i_size_read() here, the i_size
1018          * cannot change under us because we hold i_mutex.
1019          *
1020          * But it's important to update i_size while still holding page lock:
1021          * page writeout could otherwise come in and zero beyond i_size.
1022          */
1023         if (pos + copied > inode->i_size) {
1024                 i_size_write(inode, pos + copied);
1025                 i_size_changed = 1;
1026         }
1027
1028         if (pos + copied >  EXT4_I(inode)->i_disksize) {
1029                 /* We need to mark inode dirty even if
1030                  * new_i_size is less that inode->i_size
1031                  * bu greater than i_disksize.(hint delalloc)
1032                  */
1033                 ext4_update_i_disksize(inode, (pos + copied));
1034                 i_size_changed = 1;
1035         }
1036         unlock_page(page);
1037         page_cache_release(page);
1038
1039         /*
1040          * Don't mark the inode dirty under page lock. First, it unnecessarily
1041          * makes the holding time of page lock longer. Second, it forces lock
1042          * ordering of page lock and transaction start for journaling
1043          * filesystems.
1044          */
1045         if (i_size_changed)
1046                 ext4_mark_inode_dirty(handle, inode);
1047
1048         return copied;
1049 }
1050
1051 /*
1052  * We need to pick up the new inode size which generic_commit_write gave us
1053  * `file' can be NULL - eg, when called from page_symlink().
1054  *
1055  * ext4 never places buffers on inode->i_mapping->private_list.  metadata
1056  * buffers are managed internally.
1057  */
1058 static int ext4_ordered_write_end(struct file *file,
1059                                   struct address_space *mapping,
1060                                   loff_t pos, unsigned len, unsigned copied,
1061                                   struct page *page, void *fsdata)
1062 {
1063         handle_t *handle = ext4_journal_current_handle();
1064         struct inode *inode = mapping->host;
1065         int ret = 0, ret2;
1066
1067         trace_ext4_ordered_write_end(inode, pos, len, copied);
1068         ret = ext4_jbd2_file_inode(handle, inode);
1069
1070         if (ret == 0) {
1071                 ret2 = ext4_generic_write_end(file, mapping, pos, len, copied,
1072                                                         page, fsdata);
1073                 copied = ret2;
1074                 if (pos + len > inode->i_size && ext4_can_truncate(inode))
1075                         /* if we have allocated more blocks and copied
1076                          * less. We will have blocks allocated outside
1077                          * inode->i_size. So truncate them
1078                          */
1079                         ext4_orphan_add(handle, inode);
1080                 if (ret2 < 0)
1081                         ret = ret2;
1082         } else {
1083                 unlock_page(page);
1084                 page_cache_release(page);
1085         }
1086
1087         ret2 = ext4_journal_stop(handle);
1088         if (!ret)
1089                 ret = ret2;
1090
1091         if (pos + len > inode->i_size) {
1092                 ext4_truncate_failed_write(inode);
1093                 /*
1094                  * If truncate failed early the inode might still be
1095                  * on the orphan list; we need to make sure the inode
1096                  * is removed from the orphan list in that case.
1097                  */
1098                 if (inode->i_nlink)
1099                         ext4_orphan_del(NULL, inode);
1100         }
1101
1102
1103         return ret ? ret : copied;
1104 }
1105
1106 static int ext4_writeback_write_end(struct file *file,
1107                                     struct address_space *mapping,
1108                                     loff_t pos, unsigned len, unsigned copied,
1109                                     struct page *page, void *fsdata)
1110 {
1111         handle_t *handle = ext4_journal_current_handle();
1112         struct inode *inode = mapping->host;
1113         int ret = 0, ret2;
1114
1115         trace_ext4_writeback_write_end(inode, pos, len, copied);
1116         ret2 = ext4_generic_write_end(file, mapping, pos, len, copied,
1117                                                         page, fsdata);
1118         copied = ret2;
1119         if (pos + len > inode->i_size && ext4_can_truncate(inode))
1120                 /* if we have allocated more blocks and copied
1121                  * less. We will have blocks allocated outside
1122                  * inode->i_size. So truncate them
1123                  */
1124                 ext4_orphan_add(handle, inode);
1125
1126         if (ret2 < 0)
1127                 ret = ret2;
1128
1129         ret2 = ext4_journal_stop(handle);
1130         if (!ret)
1131                 ret = ret2;
1132
1133         if (pos + len > inode->i_size) {
1134                 ext4_truncate_failed_write(inode);
1135                 /*
1136                  * If truncate failed early the inode might still be
1137                  * on the orphan list; we need to make sure the inode
1138                  * is removed from the orphan list in that case.
1139                  */
1140                 if (inode->i_nlink)
1141                         ext4_orphan_del(NULL, inode);
1142         }
1143
1144         return ret ? ret : copied;
1145 }
1146
1147 static int ext4_journalled_write_end(struct file *file,
1148                                      struct address_space *mapping,
1149                                      loff_t pos, unsigned len, unsigned copied,
1150                                      struct page *page, void *fsdata)
1151 {
1152         handle_t *handle = ext4_journal_current_handle();
1153         struct inode *inode = mapping->host;
1154         int ret = 0, ret2;
1155         int partial = 0;
1156         unsigned from, to;
1157         loff_t new_i_size;
1158
1159         trace_ext4_journalled_write_end(inode, pos, len, copied);
1160         from = pos & (PAGE_CACHE_SIZE - 1);
1161         to = from + len;
1162
1163         BUG_ON(!ext4_handle_valid(handle));
1164
1165         if (ext4_has_inline_data(inode))
1166                 copied = ext4_write_inline_data_end(inode, pos, len,
1167                                                     copied, page);
1168         else {
1169                 if (copied < len) {
1170                         if (!PageUptodate(page))
1171                                 copied = 0;
1172                         page_zero_new_buffers(page, from+copied, to);
1173                 }
1174
1175                 ret = ext4_walk_page_buffers(handle, page_buffers(page), from,
1176                                              to, &partial, write_end_fn);
1177                 if (!partial)
1178                         SetPageUptodate(page);
1179         }
1180         new_i_size = pos + copied;
1181         if (new_i_size > inode->i_size)
1182                 i_size_write(inode, pos+copied);
1183         ext4_set_inode_state(inode, EXT4_STATE_JDATA);
1184         EXT4_I(inode)->i_datasync_tid = handle->h_transaction->t_tid;
1185         if (new_i_size > EXT4_I(inode)->i_disksize) {
1186                 ext4_update_i_disksize(inode, new_i_size);
1187                 ret2 = ext4_mark_inode_dirty(handle, inode);
1188                 if (!ret)
1189                         ret = ret2;
1190         }
1191
1192         unlock_page(page);
1193         page_cache_release(page);
1194         if (pos + len > inode->i_size && ext4_can_truncate(inode))
1195                 /* if we have allocated more blocks and copied
1196                  * less. We will have blocks allocated outside
1197                  * inode->i_size. So truncate them
1198                  */
1199                 ext4_orphan_add(handle, inode);
1200
1201         ret2 = ext4_journal_stop(handle);
1202         if (!ret)
1203                 ret = ret2;
1204         if (pos + len > inode->i_size) {
1205                 ext4_truncate_failed_write(inode);
1206                 /*
1207                  * If truncate failed early the inode might still be
1208                  * on the orphan list; we need to make sure the inode
1209                  * is removed from the orphan list in that case.
1210                  */
1211                 if (inode->i_nlink)
1212                         ext4_orphan_del(NULL, inode);
1213         }
1214
1215         return ret ? ret : copied;
1216 }
1217
1218 /*
1219  * Reserve a single cluster located at lblock
1220  */
1221 static int ext4_da_reserve_space(struct inode *inode, ext4_lblk_t lblock)
1222 {
1223         int retries = 0;
1224         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1225         struct ext4_inode_info *ei = EXT4_I(inode);
1226         unsigned int md_needed;
1227         int ret;
1228         ext4_lblk_t save_last_lblock;
1229         int save_len;
1230
1231         /*
1232          * We will charge metadata quota at writeout time; this saves
1233          * us from metadata over-estimation, though we may go over by
1234          * a small amount in the end.  Here we just reserve for data.
1235          */
1236         ret = dquot_reserve_block(inode, EXT4_C2B(sbi, 1));
1237         if (ret)
1238                 return ret;
1239
1240         /*
1241          * recalculate the amount of metadata blocks to reserve
1242          * in order to allocate nrblocks
1243          * worse case is one extent per block
1244          */
1245 repeat:
1246         spin_lock(&ei->i_block_reservation_lock);
1247         /*
1248          * ext4_calc_metadata_amount() has side effects, which we have
1249          * to be prepared undo if we fail to claim space.
1250          */
1251         save_len = ei->i_da_metadata_calc_len;
1252         save_last_lblock = ei->i_da_metadata_calc_last_lblock;
1253         md_needed = EXT4_NUM_B2C(sbi,
1254                                  ext4_calc_metadata_amount(inode, lblock));
1255         trace_ext4_da_reserve_space(inode, md_needed);
1256
1257         /*
1258          * We do still charge estimated metadata to the sb though;
1259          * we cannot afford to run out of free blocks.
1260          */
1261         if (ext4_claim_free_clusters(sbi, md_needed + 1, 0)) {
1262                 ei->i_da_metadata_calc_len = save_len;
1263                 ei->i_da_metadata_calc_last_lblock = save_last_lblock;
1264                 spin_unlock(&ei->i_block_reservation_lock);
1265                 if (ext4_should_retry_alloc(inode->i_sb, &retries)) {
1266                         yield();
1267                         goto repeat;
1268                 }
1269                 dquot_release_reservation_block(inode, EXT4_C2B(sbi, 1));
1270                 return -ENOSPC;
1271         }
1272         ei->i_reserved_data_blocks++;
1273         ei->i_reserved_meta_blocks += md_needed;
1274         spin_unlock(&ei->i_block_reservation_lock);
1275
1276         return 0;       /* success */
1277 }
1278
1279 static void ext4_da_release_space(struct inode *inode, int to_free)
1280 {
1281         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1282         struct ext4_inode_info *ei = EXT4_I(inode);
1283
1284         if (!to_free)
1285                 return;         /* Nothing to release, exit */
1286
1287         spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
1288
1289         trace_ext4_da_release_space(inode, to_free);
1290         if (unlikely(to_free > ei->i_reserved_data_blocks)) {
1291                 /*
1292                  * if there aren't enough reserved blocks, then the
1293                  * counter is messed up somewhere.  Since this
1294                  * function is called from invalidate page, it's
1295                  * harmless to return without any action.
1296                  */
1297                 ext4_warning(inode->i_sb, "ext4_da_release_space: "
1298                          "ino %lu, to_free %d with only %d reserved "
1299                          "data blocks", inode->i_ino, to_free,
1300                          ei->i_reserved_data_blocks);
1301                 WARN_ON(1);
1302                 to_free = ei->i_reserved_data_blocks;
1303         }
1304         ei->i_reserved_data_blocks -= to_free;
1305
1306         if (ei->i_reserved_data_blocks == 0) {
1307                 /*
1308                  * We can release all of the reserved metadata blocks
1309                  * only when we have written all of the delayed
1310                  * allocation blocks.
1311                  * Note that in case of bigalloc, i_reserved_meta_blocks,
1312                  * i_reserved_data_blocks, etc. refer to number of clusters.
1313                  */
1314                 percpu_counter_sub(&sbi->s_dirtyclusters_counter,
1315                                    ei->i_reserved_meta_blocks);
1316                 ei->i_reserved_meta_blocks = 0;
1317                 ei->i_da_metadata_calc_len = 0;
1318         }
1319
1320         /* update fs dirty data blocks counter */
1321         percpu_counter_sub(&sbi->s_dirtyclusters_counter, to_free);
1322
1323         spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
1324
1325         dquot_release_reservation_block(inode, EXT4_C2B(sbi, to_free));
1326 }
1327
1328 static void ext4_da_page_release_reservation(struct page *page,
1329                                              unsigned long offset)
1330 {
1331         int to_release = 0;
1332         struct buffer_head *head, *bh;
1333         unsigned int curr_off = 0;
1334         struct inode *inode = page->mapping->host;
1335         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1336         int num_clusters;
1337         ext4_fsblk_t lblk;
1338
1339         head = page_buffers(page);
1340         bh = head;
1341         do {
1342                 unsigned int next_off = curr_off + bh->b_size;
1343
1344                 if ((offset <= curr_off) && (buffer_delay(bh))) {
1345                         to_release++;
1346                         clear_buffer_delay(bh);
1347                 }
1348                 curr_off = next_off;
1349         } while ((bh = bh->b_this_page) != head);
1350
1351         if (to_release) {
1352                 lblk = page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
1353                 ext4_es_remove_extent(inode, lblk, to_release);
1354         }
1355
1356         /* If we have released all the blocks belonging to a cluster, then we
1357          * need to release the reserved space for that cluster. */
1358         num_clusters = EXT4_NUM_B2C(sbi, to_release);
1359         while (num_clusters > 0) {
1360                 lblk = (page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits)) +
1361                         ((num_clusters - 1) << sbi->s_cluster_bits);
1362                 if (sbi->s_cluster_ratio == 1 ||
1363                     !ext4_find_delalloc_cluster(inode, lblk))
1364                         ext4_da_release_space(inode, 1);
1365
1366                 num_clusters--;
1367         }
1368 }
1369
1370 /*
1371  * Delayed allocation stuff
1372  */
1373
1374 /*
1375  * mpage_da_submit_io - walks through extent of pages and try to write
1376  * them with writepage() call back
1377  *
1378  * @mpd->inode: inode
1379  * @mpd->first_page: first page of the extent
1380  * @mpd->next_page: page after the last page of the extent
1381  *
1382  * By the time mpage_da_submit_io() is called we expect all blocks
1383  * to be allocated. this may be wrong if allocation failed.
1384  *
1385  * As pages are already locked by write_cache_pages(), we can't use it
1386  */
1387 static int mpage_da_submit_io(struct mpage_da_data *mpd,
1388                               struct ext4_map_blocks *map)
1389 {
1390         struct pagevec pvec;
1391         unsigned long index, end;
1392         int ret = 0, err, nr_pages, i;
1393         struct inode *inode = mpd->inode;
1394         struct address_space *mapping = inode->i_mapping;
1395         loff_t size = i_size_read(inode);
1396         unsigned int len, block_start;
1397         struct buffer_head *bh, *page_bufs = NULL;
1398         sector_t pblock = 0, cur_logical = 0;
1399         struct ext4_io_submit io_submit;
1400
1401         BUG_ON(mpd->next_page <= mpd->first_page);
1402         memset(&io_submit, 0, sizeof(io_submit));
1403         /*
1404          * We need to start from the first_page to the next_page - 1
1405          * to make sure we also write the mapped dirty buffer_heads.
1406          * If we look at mpd->b_blocknr we would only be looking
1407          * at the currently mapped buffer_heads.
1408          */
1409         index = mpd->first_page;
1410         end = mpd->next_page - 1;
1411
1412         pagevec_init(&pvec, 0);
1413         while (index <= end) {
1414                 nr_pages = pagevec_lookup(&pvec, mapping, index, PAGEVEC_SIZE);
1415                 if (nr_pages == 0)
1416                         break;
1417                 for (i = 0; i < nr_pages; i++) {
1418                         int skip_page = 0;
1419                         struct page *page = pvec.pages[i];
1420
1421                         index = page->index;
1422                         if (index > end)
1423                                 break;
1424
1425                         if (index == size >> PAGE_CACHE_SHIFT)
1426                                 len = size & ~PAGE_CACHE_MASK;
1427                         else
1428                                 len = PAGE_CACHE_SIZE;
1429                         if (map) {
1430                                 cur_logical = index << (PAGE_CACHE_SHIFT -
1431                                                         inode->i_blkbits);
1432                                 pblock = map->m_pblk + (cur_logical -
1433                                                         map->m_lblk);
1434                         }
1435                         index++;
1436
1437                         BUG_ON(!PageLocked(page));
1438                         BUG_ON(PageWriteback(page));
1439
1440                         bh = page_bufs = page_buffers(page);
1441                         block_start = 0;
1442                         do {
1443                                 if (map && (cur_logical >= map->m_lblk) &&
1444                                     (cur_logical <= (map->m_lblk +
1445                                                      (map->m_len - 1)))) {
1446                                         if (buffer_delay(bh)) {
1447                                                 clear_buffer_delay(bh);
1448                                                 bh->b_blocknr = pblock;
1449                                         }
1450                                         if (buffer_unwritten(bh) ||
1451                                             buffer_mapped(bh))
1452                                                 BUG_ON(bh->b_blocknr != pblock);
1453                                         if (map->m_flags & EXT4_MAP_UNINIT)
1454                                                 set_buffer_uninit(bh);
1455                                         clear_buffer_unwritten(bh);
1456                                 }
1457
1458                                 /*
1459                                  * skip page if block allocation undone and
1460                                  * block is dirty
1461                                  */
1462                                 if (ext4_bh_delay_or_unwritten(NULL, bh))
1463                                         skip_page = 1;
1464                                 bh = bh->b_this_page;
1465                                 block_start += bh->b_size;
1466                                 cur_logical++;
1467                                 pblock++;
1468                         } while (bh != page_bufs);
1469
1470                         if (skip_page) {
1471                                 unlock_page(page);
1472                                 continue;
1473                         }
1474
1475                         clear_page_dirty_for_io(page);
1476                         err = ext4_bio_write_page(&io_submit, page, len,
1477                                                   mpd->wbc);
1478                         if (!err)
1479                                 mpd->pages_written++;
1480                         /*
1481                          * In error case, we have to continue because
1482                          * remaining pages are still locked
1483                          */
1484                         if (ret == 0)
1485                                 ret = err;
1486                 }
1487                 pagevec_release(&pvec);
1488         }
1489         ext4_io_submit(&io_submit);
1490         return ret;
1491 }
1492
1493 static void ext4_da_block_invalidatepages(struct mpage_da_data *mpd)
1494 {
1495         int nr_pages, i;
1496         pgoff_t index, end;
1497         struct pagevec pvec;
1498         struct inode *inode = mpd->inode;
1499         struct address_space *mapping = inode->i_mapping;
1500         ext4_lblk_t start, last;
1501
1502         index = mpd->first_page;
1503         end   = mpd->next_page - 1;
1504
1505         start = index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
1506         last = end << (PAGE_CACHE_SHIFT - inode->i_blkbits);
1507         ext4_es_remove_extent(inode, start, last - start + 1);
1508
1509         pagevec_init(&pvec, 0);
1510         while (index <= end) {
1511                 nr_pages = pagevec_lookup(&pvec, mapping, index, PAGEVEC_SIZE);
1512                 if (nr_pages == 0)
1513                         break;
1514                 for (i = 0; i < nr_pages; i++) {
1515                         struct page *page = pvec.pages[i];
1516                         if (page->index > end)
1517                                 break;
1518                         BUG_ON(!PageLocked(page));
1519                         BUG_ON(PageWriteback(page));
1520                         block_invalidatepage(page, 0);
1521                         ClearPageUptodate(page);
1522                         unlock_page(page);
1523                 }
1524                 index = pvec.pages[nr_pages - 1]->index + 1;
1525                 pagevec_release(&pvec);
1526         }
1527         return;
1528 }
1529
1530 static void ext4_print_free_blocks(struct inode *inode)
1531 {
1532         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1533         struct super_block *sb = inode->i_sb;
1534
1535         ext4_msg(sb, KERN_CRIT, "Total free blocks count %lld",
1536                EXT4_C2B(EXT4_SB(inode->i_sb),
1537                         ext4_count_free_clusters(inode->i_sb)));
1538         ext4_msg(sb, KERN_CRIT, "Free/Dirty block details");
1539         ext4_msg(sb, KERN_CRIT, "free_blocks=%lld",
1540                (long long) EXT4_C2B(EXT4_SB(inode->i_sb),
1541                 percpu_counter_sum(&sbi->s_freeclusters_counter)));
1542         ext4_msg(sb, KERN_CRIT, "dirty_blocks=%lld",
1543                (long long) EXT4_C2B(EXT4_SB(inode->i_sb),
1544                 percpu_counter_sum(&sbi->s_dirtyclusters_counter)));
1545         ext4_msg(sb, KERN_CRIT, "Block reservation details");
1546         ext4_msg(sb, KERN_CRIT, "i_reserved_data_blocks=%u",
1547                  EXT4_I(inode)->i_reserved_data_blocks);
1548         ext4_msg(sb, KERN_CRIT, "i_reserved_meta_blocks=%u",
1549                EXT4_I(inode)->i_reserved_meta_blocks);
1550         return;
1551 }
1552
1553 /*
1554  * mpage_da_map_and_submit - go through given space, map them
1555  *       if necessary, and then submit them for I/O
1556  *
1557  * @mpd - bh describing space
1558  *
1559  * The function skips space we know is already mapped to disk blocks.
1560  *
1561  */
1562 static void mpage_da_map_and_submit(struct mpage_da_data *mpd)
1563 {
1564         int err, blks, get_blocks_flags;
1565         struct ext4_map_blocks map, *mapp = NULL;
1566         sector_t next = mpd->b_blocknr;
1567         unsigned max_blocks = mpd->b_size >> mpd->inode->i_blkbits;
1568         loff_t disksize = EXT4_I(mpd->inode)->i_disksize;
1569         handle_t *handle = NULL;
1570
1571         /*
1572          * If the blocks are mapped already, or we couldn't accumulate
1573          * any blocks, then proceed immediately to the submission stage.
1574          */
1575         if ((mpd->b_size == 0) ||
1576             ((mpd->b_state  & (1 << BH_Mapped)) &&
1577              !(mpd->b_state & (1 << BH_Delay)) &&
1578              !(mpd->b_state & (1 << BH_Unwritten))))
1579                 goto submit_io;
1580
1581         handle = ext4_journal_current_handle();
1582         BUG_ON(!handle);
1583
1584         /*
1585          * Call ext4_map_blocks() to allocate any delayed allocation
1586          * blocks, or to convert an uninitialized extent to be
1587          * initialized (in the case where we have written into
1588          * one or more preallocated blocks).
1589          *
1590          * We pass in the magic EXT4_GET_BLOCKS_DELALLOC_RESERVE to
1591          * indicate that we are on the delayed allocation path.  This
1592          * affects functions in many different parts of the allocation
1593          * call path.  This flag exists primarily because we don't
1594          * want to change *many* call functions, so ext4_map_blocks()
1595          * will set the EXT4_STATE_DELALLOC_RESERVED flag once the
1596          * inode's allocation semaphore is taken.
1597          *
1598          * If the blocks in questions were delalloc blocks, set
1599          * EXT4_GET_BLOCKS_DELALLOC_RESERVE so the delalloc accounting
1600          * variables are updated after the blocks have been allocated.
1601          */
1602         map.m_lblk = next;
1603         map.m_len = max_blocks;
1604         get_blocks_flags = EXT4_GET_BLOCKS_CREATE;
1605         if (ext4_should_dioread_nolock(mpd->inode))
1606                 get_blocks_flags |= EXT4_GET_BLOCKS_IO_CREATE_EXT;
1607         if (mpd->b_state & (1 << BH_Delay))
1608                 get_blocks_flags |= EXT4_GET_BLOCKS_DELALLOC_RESERVE;
1609
1610         blks = ext4_map_blocks(handle, mpd->inode, &map, get_blocks_flags);
1611         if (blks < 0) {
1612                 struct super_block *sb = mpd->inode->i_sb;
1613
1614                 err = blks;
1615                 /*
1616                  * If get block returns EAGAIN or ENOSPC and there
1617                  * appears to be free blocks we will just let
1618                  * mpage_da_submit_io() unlock all of the pages.
1619                  */
1620                 if (err == -EAGAIN)
1621                         goto submit_io;
1622
1623                 if (err == -ENOSPC && ext4_count_free_clusters(sb)) {
1624                         mpd->retval = err;
1625                         goto submit_io;
1626                 }
1627
1628                 /*
1629                  * get block failure will cause us to loop in
1630                  * writepages, because a_ops->writepage won't be able
1631                  * to make progress. The page will be redirtied by
1632                  * writepage and writepages will again try to write
1633                  * the same.
1634                  */
1635                 if (!(EXT4_SB(sb)->s_mount_flags & EXT4_MF_FS_ABORTED)) {
1636                         ext4_msg(sb, KERN_CRIT,
1637                                  "delayed block allocation failed for inode %lu "
1638                                  "at logical offset %llu with max blocks %zd "
1639                                  "with error %d", mpd->inode->i_ino,
1640                                  (unsigned long long) next,
1641                                  mpd->b_size >> mpd->inode->i_blkbits, err);
1642                         ext4_msg(sb, KERN_CRIT,
1643                                 "This should not happen!! Data will be lost");
1644                         if (err == -ENOSPC)
1645                                 ext4_print_free_blocks(mpd->inode);
1646                 }
1647                 /* invalidate all the pages */
1648                 ext4_da_block_invalidatepages(mpd);
1649
1650                 /* Mark this page range as having been completed */
1651                 mpd->io_done = 1;
1652                 return;
1653         }
1654         BUG_ON(blks == 0);
1655
1656         mapp = &map;
1657         if (map.m_flags & EXT4_MAP_NEW) {
1658                 struct block_device *bdev = mpd->inode->i_sb->s_bdev;
1659                 int i;
1660
1661                 for (i = 0; i < map.m_len; i++)
1662                         unmap_underlying_metadata(bdev, map.m_pblk + i);
1663         }
1664
1665         /*
1666          * Update on-disk size along with block allocation.
1667          */
1668         disksize = ((loff_t) next + blks) << mpd->inode->i_blkbits;
1669         if (disksize > i_size_read(mpd->inode))
1670                 disksize = i_size_read(mpd->inode);
1671         if (disksize > EXT4_I(mpd->inode)->i_disksize) {
1672                 ext4_update_i_disksize(mpd->inode, disksize);
1673                 err = ext4_mark_inode_dirty(handle, mpd->inode);
1674                 if (err)
1675                         ext4_error(mpd->inode->i_sb,
1676                                    "Failed to mark inode %lu dirty",
1677                                    mpd->inode->i_ino);
1678         }
1679
1680 submit_io:
1681         mpage_da_submit_io(mpd, mapp);
1682         mpd->io_done = 1;
1683 }
1684
1685 #define BH_FLAGS ((1 << BH_Uptodate) | (1 << BH_Mapped) | \
1686                 (1 << BH_Delay) | (1 << BH_Unwritten))
1687
1688 /*
1689  * mpage_add_bh_to_extent - try to add one more block to extent of blocks
1690  *
1691  * @mpd->lbh - extent of blocks
1692  * @logical - logical number of the block in the file
1693  * @b_state - b_state of the buffer head added
1694  *
1695  * the function is used to collect contig. blocks in same state
1696  */
1697 static void mpage_add_bh_to_extent(struct mpage_da_data *mpd, sector_t logical,
1698                                    unsigned long b_state)
1699 {
1700         sector_t next;
1701         int blkbits = mpd->inode->i_blkbits;
1702         int nrblocks = mpd->b_size >> blkbits;
1703
1704         /*
1705          * XXX Don't go larger than mballoc is willing to allocate
1706          * This is a stopgap solution.  We eventually need to fold
1707          * mpage_da_submit_io() into this function and then call
1708          * ext4_map_blocks() multiple times in a loop
1709          */
1710         if (nrblocks >= (8*1024*1024 >> blkbits))
1711                 goto flush_it;
1712
1713         /* check if the reserved journal credits might overflow */
1714         if (!ext4_test_inode_flag(mpd->inode, EXT4_INODE_EXTENTS)) {
1715                 if (nrblocks >= EXT4_MAX_TRANS_DATA) {
1716                         /*
1717                          * With non-extent format we are limited by the journal
1718                          * credit available.  Total credit needed to insert
1719                          * nrblocks contiguous blocks is dependent on the
1720                          * nrblocks.  So limit nrblocks.
1721                          */
1722                         goto flush_it;
1723                 }
1724         }
1725         /*
1726          * First block in the extent
1727          */
1728         if (mpd->b_size == 0) {
1729                 mpd->b_blocknr = logical;
1730                 mpd->b_size = 1 << blkbits;
1731                 mpd->b_state = b_state & BH_FLAGS;
1732                 return;
1733         }
1734
1735         next = mpd->b_blocknr + nrblocks;
1736         /*
1737          * Can we merge the block to our big extent?
1738          */
1739         if (logical == next && (b_state & BH_FLAGS) == mpd->b_state) {
1740                 mpd->b_size += 1 << blkbits;
1741                 return;
1742         }
1743
1744 flush_it:
1745         /*
1746          * We couldn't merge the block to our extent, so we
1747          * need to flush current  extent and start new one
1748          */
1749         mpage_da_map_and_submit(mpd);
1750         return;
1751 }
1752
1753 static int ext4_bh_delay_or_unwritten(handle_t *handle, struct buffer_head *bh)
1754 {
1755         return (buffer_delay(bh) || buffer_unwritten(bh)) && buffer_dirty(bh);
1756 }
1757
1758 /*
1759  * This function is grabs code from the very beginning of
1760  * ext4_map_blocks, but assumes that the caller is from delayed write
1761  * time. This function looks up the requested blocks and sets the
1762  * buffer delay bit under the protection of i_data_sem.
1763  */
1764 static int ext4_da_map_blocks(struct inode *inode, sector_t iblock,
1765                               struct ext4_map_blocks *map,
1766                               struct buffer_head *bh)
1767 {
1768         struct extent_status es;
1769         int retval;
1770         sector_t invalid_block = ~((sector_t) 0xffff);
1771
1772         if (invalid_block < ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es))
1773                 invalid_block = ~0;
1774
1775         map->m_flags = 0;
1776         ext_debug("ext4_da_map_blocks(): inode %lu, max_blocks %u,"
1777                   "logical block %lu\n", inode->i_ino, map->m_len,
1778                   (unsigned long) map->m_lblk);
1779
1780         /* Lookup extent status tree firstly */
1781         if (ext4_es_lookup_extent(inode, iblock, &es)) {
1782
1783                 if (ext4_es_is_hole(&es)) {
1784                         retval = 0;
1785                         down_read((&EXT4_I(inode)->i_data_sem));
1786                         goto add_delayed;
1787                 }
1788
1789                 /*
1790                  * Delayed extent could be allocated by fallocate.
1791                  * So we need to check it.
1792                  */
1793                 if (ext4_es_is_delayed(&es) && !ext4_es_is_unwritten(&es)) {
1794                         map_bh(bh, inode->i_sb, invalid_block);
1795                         set_buffer_new(bh);
1796                         set_buffer_delay(bh);
1797                         return 0;
1798                 }
1799
1800                 map->m_pblk = ext4_es_pblock(&es) + iblock - es.es_lblk;
1801                 retval = es.es_len - (iblock - es.es_lblk);
1802                 if (retval > map->m_len)
1803                         retval = map->m_len;
1804                 map->m_len = retval;
1805                 if (ext4_es_is_written(&es))
1806                         map->m_flags |= EXT4_MAP_MAPPED;
1807                 else if (ext4_es_is_unwritten(&es))
1808                         map->m_flags |= EXT4_MAP_UNWRITTEN;
1809                 else
1810                         BUG_ON(1);
1811
1812                 return retval;
1813         }
1814
1815         /*
1816          * Try to see if we can get the block without requesting a new
1817          * file system block.
1818          */
1819         down_read((&EXT4_I(inode)->i_data_sem));
1820         if (ext4_has_inline_data(inode)) {
1821                 /*
1822                  * We will soon create blocks for this page, and let
1823                  * us pretend as if the blocks aren't allocated yet.
1824                  * In case of clusters, we have to handle the work
1825                  * of mapping from cluster so that the reserved space
1826                  * is calculated properly.
1827                  */
1828                 if ((EXT4_SB(inode->i_sb)->s_cluster_ratio > 1) &&
1829                     ext4_find_delalloc_cluster(inode, map->m_lblk))
1830                         map->m_flags |= EXT4_MAP_FROM_CLUSTER;
1831                 retval = 0;
1832         } else if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
1833                 retval = ext4_ext_map_blocks(NULL, inode, map,
1834                                              EXT4_GET_BLOCKS_NO_PUT_HOLE);
1835         else
1836                 retval = ext4_ind_map_blocks(NULL, inode, map,
1837                                              EXT4_GET_BLOCKS_NO_PUT_HOLE);
1838
1839 add_delayed:
1840         if (retval == 0) {
1841                 int ret;
1842                 /*
1843                  * XXX: __block_prepare_write() unmaps passed block,
1844                  * is it OK?
1845                  */
1846                 /* If the block was allocated from previously allocated cluster,
1847                  * then we dont need to reserve it again. */
1848                 if (!(map->m_flags & EXT4_MAP_FROM_CLUSTER)) {
1849                         ret = ext4_da_reserve_space(inode, iblock);
1850                         if (ret) {
1851                                 /* not enough space to reserve */
1852                                 retval = ret;
1853                                 goto out_unlock;
1854                         }
1855                 }
1856
1857                 ret = ext4_es_insert_extent(inode, map->m_lblk, map->m_len,
1858                                             ~0, EXTENT_STATUS_DELAYED);
1859                 if (ret) {
1860                         retval = ret;
1861                         goto out_unlock;
1862                 }
1863
1864                 /* Clear EXT4_MAP_FROM_CLUSTER flag since its purpose is served
1865                  * and it should not appear on the bh->b_state.
1866                  */
1867                 map->m_flags &= ~EXT4_MAP_FROM_CLUSTER;
1868
1869                 map_bh(bh, inode->i_sb, invalid_block);
1870                 set_buffer_new(bh);
1871                 set_buffer_delay(bh);
1872         } else if (retval > 0) {
1873                 int ret;
1874                 unsigned long long status;
1875
1876                 status = map->m_flags & EXT4_MAP_UNWRITTEN ?
1877                                 EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
1878                 ret = ext4_es_insert_extent(inode, map->m_lblk, map->m_len,
1879                                             map->m_pblk, status);
1880                 if (ret != 0)
1881                         retval = ret;
1882         }
1883
1884 out_unlock:
1885         up_read((&EXT4_I(inode)->i_data_sem));
1886
1887         return retval;
1888 }
1889
1890 /*
1891  * This is a special get_blocks_t callback which is used by
1892  * ext4_da_write_begin().  It will either return mapped block or
1893  * reserve space for a single block.
1894  *
1895  * For delayed buffer_head we have BH_Mapped, BH_New, BH_Delay set.
1896  * We also have b_blocknr = -1 and b_bdev initialized properly
1897  *
1898  * For unwritten buffer_head we have BH_Mapped, BH_New, BH_Unwritten set.
1899  * We also have b_blocknr = physicalblock mapping unwritten extent and b_bdev
1900  * initialized properly.
1901  */
1902 int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
1903                            struct buffer_head *bh, int create)
1904 {
1905         struct ext4_map_blocks map;
1906         int ret = 0;
1907
1908         BUG_ON(create == 0);
1909         BUG_ON(bh->b_size != inode->i_sb->s_blocksize);
1910
1911         map.m_lblk = iblock;
1912         map.m_len = 1;
1913
1914         /*
1915          * first, we need to know whether the block is allocated already
1916          * preallocated blocks are unmapped but should treated
1917          * the same as allocated blocks.
1918          */
1919         ret = ext4_da_map_blocks(inode, iblock, &map, bh);
1920         if (ret <= 0)
1921                 return ret;
1922
1923         map_bh(bh, inode->i_sb, map.m_pblk);
1924         bh->b_state = (bh->b_state & ~EXT4_MAP_FLAGS) | map.m_flags;
1925
1926         if (buffer_unwritten(bh)) {
1927                 /* A delayed write to unwritten bh should be marked
1928                  * new and mapped.  Mapped ensures that we don't do
1929                  * get_block multiple times when we write to the same
1930                  * offset and new ensures that we do proper zero out
1931                  * for partial write.
1932                  */
1933                 set_buffer_new(bh);
1934                 set_buffer_mapped(bh);
1935         }
1936         return 0;
1937 }
1938
1939 static int bget_one(handle_t *handle, struct buffer_head *bh)
1940 {
1941         get_bh(bh);
1942         return 0;
1943 }
1944
1945 static int bput_one(handle_t *handle, struct buffer_head *bh)
1946 {
1947         put_bh(bh);
1948         return 0;
1949 }
1950
1951 static int __ext4_journalled_writepage(struct page *page,
1952                                        unsigned int len)
1953 {
1954         struct address_space *mapping = page->mapping;
1955         struct inode *inode = mapping->host;
1956         struct buffer_head *page_bufs = NULL;
1957         handle_t *handle = NULL;
1958         int ret = 0, err = 0;
1959         int inline_data = ext4_has_inline_data(inode);
1960         struct buffer_head *inode_bh = NULL;
1961
1962         ClearPageChecked(page);
1963
1964         if (inline_data) {
1965                 BUG_ON(page->index != 0);
1966                 BUG_ON(len > ext4_get_max_inline_size(inode));
1967                 inode_bh = ext4_journalled_write_inline_data(inode, len, page);
1968                 if (inode_bh == NULL)
1969                         goto out;
1970         } else {
1971                 page_bufs = page_buffers(page);
1972                 if (!page_bufs) {
1973                         BUG();
1974                         goto out;
1975                 }
1976                 ext4_walk_page_buffers(handle, page_bufs, 0, len,
1977                                        NULL, bget_one);
1978         }
1979         /* As soon as we unlock the page, it can go away, but we have
1980          * references to buffers so we are safe */
1981         unlock_page(page);
1982
1983         handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE,
1984                                     ext4_writepage_trans_blocks(inode));
1985         if (IS_ERR(handle)) {
1986                 ret = PTR_ERR(handle);
1987                 goto out;
1988         }
1989
1990         BUG_ON(!ext4_handle_valid(handle));
1991
1992         if (inline_data) {
1993                 ret = ext4_journal_get_write_access(handle, inode_bh);
1994
1995                 err = ext4_handle_dirty_metadata(handle, inode, inode_bh);
1996
1997         } else {
1998                 ret = ext4_walk_page_buffers(handle, page_bufs, 0, len, NULL,
1999                                              do_journal_get_write_access);
2000
2001                 err = ext4_walk_page_buffers(handle, page_bufs, 0, len, NULL,
2002                                              write_end_fn);
2003         }
2004         if (ret == 0)
2005                 ret = err;
2006         EXT4_I(inode)->i_datasync_tid = handle->h_transaction->t_tid;
2007         err = ext4_journal_stop(handle);
2008         if (!ret)
2009                 ret = err;
2010
2011         if (!ext4_has_inline_data(inode))
2012                 ext4_walk_page_buffers(handle, page_bufs, 0, len,
2013                                        NULL, bput_one);
2014         ext4_set_inode_state(inode, EXT4_STATE_JDATA);
2015 out:
2016         brelse(inode_bh);
2017         return ret;
2018 }
2019
2020 /*
2021  * Note that we don't need to start a transaction unless we're journaling data
2022  * because we should have holes filled from ext4_page_mkwrite(). We even don't
2023  * need to file the inode to the transaction's list in ordered mode because if
2024  * we are writing back data added by write(), the inode is already there and if
2025  * we are writing back data modified via mmap(), no one guarantees in which
2026  * transaction the data will hit the disk. In case we are journaling data, we
2027  * cannot start transaction directly because transaction start ranks above page
2028  * lock so we have to do some magic.
2029  *
2030  * This function can get called via...
2031  *   - ext4_da_writepages after taking page lock (have journal handle)
2032  *   - journal_submit_inode_data_buffers (no journal handle)
2033  *   - shrink_page_list via the kswapd/direct reclaim (no journal handle)
2034  *   - grab_page_cache when doing write_begin (have journal handle)
2035  *
2036  * We don't do any block allocation in this function. If we have page with
2037  * multiple blocks we need to write those buffer_heads that are mapped. This
2038  * is important for mmaped based write. So if we do with blocksize 1K
2039  * truncate(f, 1024);
2040  * a = mmap(f, 0, 4096);
2041  * a[0] = 'a';
2042  * truncate(f, 4096);
2043  * we have in the page first buffer_head mapped via page_mkwrite call back
2044  * but other buffer_heads would be unmapped but dirty (dirty done via the
2045  * do_wp_page). So writepage should write the first block. If we modify
2046  * the mmap area beyond 1024 we will again get a page_fault and the
2047  * page_mkwrite callback will do the block allocation and mark the
2048  * buffer_heads mapped.
2049  *
2050  * We redirty the page if we have any buffer_heads that is either delay or
2051  * unwritten in the page.
2052  *
2053  * We can get recursively called as show below.
2054  *
2055  *      ext4_writepage() -> kmalloc() -> __alloc_pages() -> page_launder() ->
2056  *              ext4_writepage()
2057  *
2058  * But since we don't do any block allocation we should not deadlock.
2059  * Page also have the dirty flag cleared so we don't get recurive page_lock.
2060  */
2061 static int ext4_writepage(struct page *page,
2062                           struct writeback_control *wbc)
2063 {
2064         int ret = 0;
2065         loff_t size;
2066         unsigned int len;
2067         struct buffer_head *page_bufs = NULL;
2068         struct inode *inode = page->mapping->host;
2069         struct ext4_io_submit io_submit;
2070
2071         trace_ext4_writepage(page);
2072         size = i_size_read(inode);
2073         if (page->index == size >> PAGE_CACHE_SHIFT)
2074                 len = size & ~PAGE_CACHE_MASK;
2075         else
2076                 len = PAGE_CACHE_SIZE;
2077
2078         page_bufs = page_buffers(page);
2079         /*
2080          * We cannot do block allocation or other extent handling in this
2081          * function. If there are buffers needing that, we have to redirty
2082          * the page. But we may reach here when we do a journal commit via
2083          * journal_submit_inode_data_buffers() and in that case we must write
2084          * allocated buffers to achieve data=ordered mode guarantees.
2085          */
2086         if (ext4_walk_page_buffers(NULL, page_bufs, 0, len, NULL,
2087                                    ext4_bh_delay_or_unwritten)) {
2088                 redirty_page_for_writepage(wbc, page);
2089                 if (current->flags & PF_MEMALLOC) {
2090                         /*
2091                          * For memory cleaning there's no point in writing only
2092                          * some buffers. So just bail out. Warn if we came here
2093                          * from direct reclaim.
2094                          */
2095                         WARN_ON_ONCE((current->flags & (PF_MEMALLOC|PF_KSWAPD))
2096                                                         == PF_MEMALLOC);
2097                         unlock_page(page);
2098                         return 0;
2099                 }
2100         }
2101
2102         if (PageChecked(page) && ext4_should_journal_data(inode))
2103                 /*
2104                  * It's mmapped pagecache.  Add buffers and journal it.  There
2105                  * doesn't seem much point in redirtying the page here.
2106                  */
2107                 return __ext4_journalled_writepage(page, len);
2108
2109         memset(&io_submit, 0, sizeof(io_submit));
2110         ret = ext4_bio_write_page(&io_submit, page, len, wbc);
2111         ext4_io_submit(&io_submit);
2112         return ret;
2113 }
2114
2115 /*
2116  * This is called via ext4_da_writepages() to
2117  * calculate the total number of credits to reserve to fit
2118  * a single extent allocation into a single transaction,
2119  * ext4_da_writpeages() will loop calling this before
2120  * the block allocation.
2121  */
2122
2123 static int ext4_da_writepages_trans_blocks(struct inode *inode)
2124 {
2125         int max_blocks = EXT4_I(inode)->i_reserved_data_blocks;
2126
2127         /*
2128          * With non-extent format the journal credit needed to
2129          * insert nrblocks contiguous block is dependent on
2130          * number of contiguous block. So we will limit
2131          * number of contiguous block to a sane value
2132          */
2133         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) &&
2134             (max_blocks > EXT4_MAX_TRANS_DATA))
2135                 max_blocks = EXT4_MAX_TRANS_DATA;
2136
2137         return ext4_chunk_trans_blocks(inode, max_blocks);
2138 }
2139
2140 /*
2141  * write_cache_pages_da - walk the list of dirty pages of the given
2142  * address space and accumulate pages that need writing, and call
2143  * mpage_da_map_and_submit to map a single contiguous memory region
2144  * and then write them.
2145  */
2146 static int write_cache_pages_da(handle_t *handle,
2147                                 struct address_space *mapping,
2148                                 struct writeback_control *wbc,
2149                                 struct mpage_da_data *mpd,
2150                                 pgoff_t *done_index)
2151 {
2152         struct buffer_head      *bh, *head;
2153         struct inode            *inode = mapping->host;
2154         struct pagevec          pvec;
2155         unsigned int            nr_pages;
2156         sector_t                logical;
2157         pgoff_t                 index, end;
2158         long                    nr_to_write = wbc->nr_to_write;
2159         int                     i, tag, ret = 0;
2160
2161         memset(mpd, 0, sizeof(struct mpage_da_data));
2162         mpd->wbc = wbc;
2163         mpd->inode = inode;
2164         pagevec_init(&pvec, 0);
2165         index = wbc->range_start >> PAGE_CACHE_SHIFT;
2166         end = wbc->range_end >> PAGE_CACHE_SHIFT;
2167
2168         if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
2169                 tag = PAGECACHE_TAG_TOWRITE;
2170         else
2171                 tag = PAGECACHE_TAG_DIRTY;
2172
2173         *done_index = index;
2174         while (index <= end) {
2175                 nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, tag,
2176                               min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1);
2177                 if (nr_pages == 0)
2178                         return 0;
2179
2180                 for (i = 0; i < nr_pages; i++) {
2181                         struct page *page = pvec.pages[i];
2182
2183                         /*
2184                          * At this point, the page may be truncated or
2185                          * invalidated (changing page->mapping to NULL), or
2186                          * even swizzled back from swapper_space to tmpfs file
2187                          * mapping. However, page->index will not change
2188                          * because we have a reference on the page.
2189                          */
2190                         if (page->index > end)
2191                                 goto out;
2192
2193                         *done_index = page->index + 1;
2194
2195                         /*
2196                          * If we can't merge this page, and we have
2197                          * accumulated an contiguous region, write it
2198                          */
2199                         if ((mpd->next_page != page->index) &&
2200                             (mpd->next_page != mpd->first_page)) {
2201                                 mpage_da_map_and_submit(mpd);
2202                                 goto ret_extent_tail;
2203                         }
2204
2205                         lock_page(page);
2206
2207                         /*
2208                          * If the page is no longer dirty, or its
2209                          * mapping no longer corresponds to inode we
2210                          * are writing (which means it has been
2211                          * truncated or invalidated), or the page is
2212                          * already under writeback and we are not
2213                          * doing a data integrity writeback, skip the page
2214                          */
2215                         if (!PageDirty(page) ||
2216                             (PageWriteback(page) &&
2217                              (wbc->sync_mode == WB_SYNC_NONE)) ||
2218                             unlikely(page->mapping != mapping)) {
2219                                 unlock_page(page);
2220                                 continue;
2221                         }
2222
2223                         wait_on_page_writeback(page);
2224                         BUG_ON(PageWriteback(page));
2225
2226                         /*
2227                          * If we have inline data and arrive here, it means that
2228                          * we will soon create the block for the 1st page, so
2229                          * we'd better clear the inline data here.
2230                          */
2231                         if (ext4_has_inline_data(inode)) {
2232                                 BUG_ON(ext4_test_inode_state(inode,
2233                                                 EXT4_STATE_MAY_INLINE_DATA));
2234                                 ext4_destroy_inline_data(handle, inode);
2235                         }
2236
2237                         if (mpd->next_page != page->index)
2238                                 mpd->first_page = page->index;
2239                         mpd->next_page = page->index + 1;
2240                         logical = (sector_t) page->index <<
2241                                 (PAGE_CACHE_SHIFT - inode->i_blkbits);
2242
2243                         /* Add all dirty buffers to mpd */
2244                         head = page_buffers(page);
2245                         bh = head;
2246                         do {
2247                                 BUG_ON(buffer_locked(bh));
2248                                 /*
2249                                  * We need to try to allocate unmapped blocks
2250                                  * in the same page.  Otherwise we won't make
2251                                  * progress with the page in ext4_writepage
2252                                  */
2253                                 if (ext4_bh_delay_or_unwritten(NULL, bh)) {
2254                                         mpage_add_bh_to_extent(mpd, logical,
2255                                                                bh->b_state);
2256                                         if (mpd->io_done)
2257                                                 goto ret_extent_tail;
2258                                 } else if (buffer_dirty(bh) &&
2259                                            buffer_mapped(bh)) {
2260                                         /*
2261                                          * mapped dirty buffer. We need to
2262                                          * update the b_state because we look
2263                                          * at b_state in mpage_da_map_blocks.
2264                                          * We don't update b_size because if we
2265                                          * find an unmapped buffer_head later
2266                                          * we need to use the b_state flag of
2267                                          * that buffer_head.
2268                                          */
2269                                         if (mpd->b_size == 0)
2270                                                 mpd->b_state =
2271                                                         bh->b_state & BH_FLAGS;
2272                                 }
2273                                 logical++;
2274                         } while ((bh = bh->b_this_page) != head);
2275
2276                         if (nr_to_write > 0) {
2277                                 nr_to_write--;
2278                                 if (nr_to_write == 0 &&
2279                                     wbc->sync_mode == WB_SYNC_NONE)
2280                                         /*
2281                                          * We stop writing back only if we are
2282                                          * not doing integrity sync. In case of
2283                                          * integrity sync we have to keep going
2284                                          * because someone may be concurrently
2285                                          * dirtying pages, and we might have
2286                                          * synced a lot of newly appeared dirty
2287                                          * pages, but have not synced all of the
2288                                          * old dirty pages.
2289                                          */
2290                                         goto out;
2291                         }
2292                 }
2293                 pagevec_release(&pvec);
2294                 cond_resched();
2295         }
2296         return 0;
2297 ret_extent_tail:
2298         ret = MPAGE_DA_EXTENT_TAIL;
2299 out:
2300         pagevec_release(&pvec);
2301         cond_resched();
2302         return ret;
2303 }
2304
2305
2306 static int ext4_da_writepages(struct address_space *mapping,
2307                               struct writeback_control *wbc)
2308 {
2309         pgoff_t index;
2310         int range_whole = 0;
2311         handle_t *handle = NULL;
2312         struct mpage_da_data mpd;
2313         struct inode *inode = mapping->host;
2314         int pages_written = 0;
2315         unsigned int max_pages;
2316         int range_cyclic, cycled = 1, io_done = 0;
2317         int needed_blocks, ret = 0;
2318         long desired_nr_to_write, nr_to_writebump = 0;
2319         loff_t range_start = wbc->range_start;
2320         struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);
2321         pgoff_t done_index = 0;
2322         pgoff_t end;
2323         struct blk_plug plug;
2324
2325         trace_ext4_da_writepages(inode, wbc);
2326
2327         /*
2328          * No pages to write? This is mainly a kludge to avoid starting
2329          * a transaction for special inodes like journal inode on last iput()
2330          * because that could violate lock ordering on umount
2331          */
2332         if (!mapping->nrpages || !mapping_tagged(mapping, PAGECACHE_TAG_DIRTY))
2333                 return 0;
2334
2335         /*
2336          * If the filesystem has aborted, it is read-only, so return
2337          * right away instead of dumping stack traces later on that
2338          * will obscure the real source of the problem.  We test
2339          * EXT4_MF_FS_ABORTED instead of sb->s_flag's MS_RDONLY because
2340          * the latter could be true if the filesystem is mounted
2341          * read-only, and in that case, ext4_da_writepages should
2342          * *never* be called, so if that ever happens, we would want
2343          * the stack trace.
2344          */
2345         if (unlikely(sbi->s_mount_flags & EXT4_MF_FS_ABORTED))
2346                 return -EROFS;
2347
2348         if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
2349                 range_whole = 1;
2350
2351         range_cyclic = wbc->range_cyclic;
2352         if (wbc->range_cyclic) {
2353                 index = mapping->writeback_index;
2354                 if (index)
2355                         cycled = 0;
2356                 wbc->range_start = index << PAGE_CACHE_SHIFT;
2357                 wbc->range_end  = LLONG_MAX;
2358                 wbc->range_cyclic = 0;
2359                 end = -1;
2360         } else {
2361                 index = wbc->range_start >> PAGE_CACHE_SHIFT;
2362                 end = wbc->range_end >> PAGE_CACHE_SHIFT;
2363         }
2364
2365         /*
2366          * This works around two forms of stupidity.  The first is in
2367          * the writeback code, which caps the maximum number of pages
2368          * written to be 1024 pages.  This is wrong on multiple
2369          * levels; different architectues have a different page size,
2370          * which changes the maximum amount of data which gets
2371          * written.  Secondly, 4 megabytes is way too small.  XFS
2372          * forces this value to be 16 megabytes by multiplying
2373          * nr_to_write parameter by four, and then relies on its
2374          * allocator to allocate larger extents to make them
2375          * contiguous.  Unfortunately this brings us to the second
2376          * stupidity, which is that ext4's mballoc code only allocates
2377          * at most 2048 blocks.  So we force contiguous writes up to
2378          * the number of dirty blocks in the inode, or
2379          * sbi->max_writeback_mb_bump whichever is smaller.
2380          */
2381         max_pages = sbi->s_max_writeback_mb_bump << (20 - PAGE_CACHE_SHIFT);
2382         if (!range_cyclic && range_whole) {
2383                 if (wbc->nr_to_write == LONG_MAX)
2384                         desired_nr_to_write = wbc->nr_to_write;
2385                 else
2386                         desired_nr_to_write = wbc->nr_to_write * 8;
2387         } else
2388                 desired_nr_to_write = ext4_num_dirty_pages(inode, index,
2389                                                            max_pages);
2390         if (desired_nr_to_write > max_pages)
2391                 desired_nr_to_write = max_pages;
2392
2393         if (wbc->nr_to_write < desired_nr_to_write) {
2394                 nr_to_writebump = desired_nr_to_write - wbc->nr_to_write;
2395                 wbc->nr_to_write = desired_nr_to_write;
2396         }
2397
2398 retry:
2399         if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
2400                 tag_pages_for_writeback(mapping, index, end);
2401
2402         blk_start_plug(&plug);
2403         while (!ret && wbc->nr_to_write > 0) {
2404
2405                 /*
2406                  * we  insert one extent at a time. So we need
2407                  * credit needed for single extent allocation.
2408                  * journalled mode is currently not supported
2409                  * by delalloc
2410                  */
2411                 BUG_ON(ext4_should_journal_data(inode));
2412                 needed_blocks = ext4_da_writepages_trans_blocks(inode);
2413
2414                 /* start a new transaction*/
2415                 handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE,
2416                                             needed_blocks);
2417                 if (IS_ERR(handle)) {
2418                         ret = PTR_ERR(handle);
2419                         ext4_msg(inode->i_sb, KERN_CRIT, "%s: jbd2_start: "
2420                                "%ld pages, ino %lu; err %d", __func__,
2421                                 wbc->nr_to_write, inode->i_ino, ret);
2422                         blk_finish_plug(&plug);
2423                         goto out_writepages;
2424                 }
2425
2426                 /*
2427                  * Now call write_cache_pages_da() to find the next
2428                  * contiguous region of logical blocks that need
2429                  * blocks to be allocated by ext4 and submit them.
2430                  */
2431                 ret = write_cache_pages_da(handle, mapping,
2432                                            wbc, &mpd, &done_index);
2433                 /*
2434                  * If we have a contiguous extent of pages and we
2435                  * haven't done the I/O yet, map the blocks and submit
2436                  * them for I/O.
2437                  */
2438                 if (!mpd.io_done && mpd.next_page != mpd.first_page) {
2439                         mpage_da_map_and_submit(&mpd);
2440                         ret = MPAGE_DA_EXTENT_TAIL;
2441                 }
2442                 trace_ext4_da_write_pages(inode, &mpd);
2443                 wbc->nr_to_write -= mpd.pages_written;
2444
2445                 ext4_journal_stop(handle);
2446
2447                 if ((mpd.retval == -ENOSPC) && sbi->s_journal) {
2448                         /* commit the transaction which would
2449                          * free blocks released in the transaction
2450                          * and try again
2451                          */
2452                         jbd2_journal_force_commit_nested(sbi->s_journal);
2453                         ret = 0;
2454                 } else if (ret == MPAGE_DA_EXTENT_TAIL) {
2455                         /*
2456                          * Got one extent now try with rest of the pages.
2457                          * If mpd.retval is set -EIO, journal is aborted.
2458                          * So we don't need to write any more.
2459                          */
2460                         pages_written += mpd.pages_written;
2461                         ret = mpd.retval;
2462                         io_done = 1;
2463                 } else if (wbc->nr_to_write)
2464                         /*
2465                          * There is no more writeout needed
2466                          * or we requested for a noblocking writeout
2467                          * and we found the device congested
2468                          */
2469                         break;
2470         }
2471         blk_finish_plug(&plug);
2472         if (!io_done && !cycled) {
2473                 cycled = 1;
2474                 index = 0;
2475                 wbc->range_start = index << PAGE_CACHE_SHIFT;
2476                 wbc->range_end  = mapping->writeback_index - 1;
2477                 goto retry;
2478         }
2479
2480         /* Update index */
2481         wbc->range_cyclic = range_cyclic;
2482         if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
2483                 /*
2484                  * set the writeback_index so that range_cyclic
2485                  * mode will write it back later
2486                  */
2487                 mapping->writeback_index = done_index;
2488
2489 out_writepages:
2490         wbc->nr_to_write -= nr_to_writebump;
2491         wbc->range_start = range_start;
2492         trace_ext4_da_writepages_result(inode, wbc, ret, pages_written);
2493         return ret;
2494 }
2495
2496 static int ext4_nonda_switch(struct super_block *sb)
2497 {
2498         s64 free_blocks, dirty_blocks;
2499         struct ext4_sb_info *sbi = EXT4_SB(sb);
2500
2501         /*
2502          * switch to non delalloc mode if we are running low
2503          * on free block. The free block accounting via percpu
2504          * counters can get slightly wrong with percpu_counter_batch getting
2505          * accumulated on each CPU without updating global counters
2506          * Delalloc need an accurate free block accounting. So switch
2507          * to non delalloc when we are near to error range.
2508          */
2509         free_blocks  = EXT4_C2B(sbi,
2510                 percpu_counter_read_positive(&sbi->s_freeclusters_counter));
2511         dirty_blocks = percpu_counter_read_positive(&sbi->s_dirtyclusters_counter);
2512         /*
2513          * Start pushing delalloc when 1/2 of free blocks are dirty.
2514          */
2515         if (dirty_blocks && (free_blocks < 2 * dirty_blocks) &&
2516             !writeback_in_progress(sb->s_bdi) &&
2517             down_read_trylock(&sb->s_umount)) {
2518                 writeback_inodes_sb(sb, WB_REASON_FS_FREE_SPACE);
2519                 up_read(&sb->s_umount);
2520         }
2521
2522         if (2 * free_blocks < 3 * dirty_blocks ||
2523                 free_blocks < (dirty_blocks + EXT4_FREECLUSTERS_WATERMARK)) {
2524                 /*
2525                  * free block count is less than 150% of dirty blocks
2526                  * or free blocks is less than watermark
2527                  */
2528                 return 1;
2529         }
2530         return 0;
2531 }
2532
2533 static int ext4_da_write_begin(struct file *file, struct address_space *mapping,
2534                                loff_t pos, unsigned len, unsigned flags,
2535                                struct page **pagep, void **fsdata)
2536 {
2537         int ret, retries = 0;
2538         struct page *page;
2539         pgoff_t index;
2540         struct inode *inode = mapping->host;
2541         handle_t *handle;
2542
2543         index = pos >> PAGE_CACHE_SHIFT;
2544
2545         if (ext4_nonda_switch(inode->i_sb)) {
2546                 *fsdata = (void *)FALL_BACK_TO_NONDELALLOC;
2547                 return ext4_write_begin(file, mapping, pos,
2548                                         len, flags, pagep, fsdata);
2549         }
2550         *fsdata = (void *)0;
2551         trace_ext4_da_write_begin(inode, pos, len, flags);
2552
2553         if (ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA)) {
2554                 ret = ext4_da_write_inline_data_begin(mapping, inode,
2555                                                       pos, len, flags,
2556                                                       pagep, fsdata);
2557                 if (ret < 0)
2558                         return ret;
2559                 if (ret == 1)
2560                         return 0;
2561         }
2562
2563         /*
2564          * grab_cache_page_write_begin() can take a long time if the
2565          * system is thrashing due to memory pressure, or if the page
2566          * is being written back.  So grab it first before we start
2567          * the transaction handle.  This also allows us to allocate
2568          * the page (if needed) without using GFP_NOFS.
2569          */
2570 retry_grab:
2571         page = grab_cache_page_write_begin(mapping, index, flags);
2572         if (!page)
2573                 return -ENOMEM;
2574         unlock_page(page);
2575
2576         /*
2577          * With delayed allocation, we don't log the i_disksize update
2578          * if there is delayed block allocation. But we still need
2579          * to journalling the i_disksize update if writes to the end
2580          * of file which has an already mapped buffer.
2581          */
2582 retry_journal:
2583         handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE, 1);
2584         if (IS_ERR(handle)) {
2585                 page_cache_release(page);
2586                 return PTR_ERR(handle);
2587         }
2588
2589         lock_page(page);
2590         if (page->mapping != mapping) {
2591                 /* The page got truncated from under us */
2592                 unlock_page(page);
2593                 page_cache_release(page);
2594                 ext4_journal_stop(handle);
2595                 goto retry_grab;
2596         }
2597         /* In case writeback began while the page was unlocked */
2598         wait_on_page_writeback(page);
2599
2600         ret = __block_write_begin(page, pos, len, ext4_da_get_block_prep);
2601         if (ret < 0) {
2602                 unlock_page(page);
2603                 ext4_journal_stop(handle);
2604                 /*
2605                  * block_write_begin may have instantiated a few blocks
2606                  * outside i_size.  Trim these off again. Don't need
2607                  * i_size_read because we hold i_mutex.
2608                  */
2609                 if (pos + len > inode->i_size)
2610                         ext4_truncate_failed_write(inode);
2611
2612                 if (ret == -ENOSPC &&
2613                     ext4_should_retry_alloc(inode->i_sb, &retries))
2614                         goto retry_journal;
2615
2616                 page_cache_release(page);
2617                 return ret;
2618         }
2619
2620         *pagep = page;
2621         return ret;
2622 }
2623
2624 /*
2625  * Check if we should update i_disksize
2626  * when write to the end of file but not require block allocation
2627  */
2628 static int ext4_da_should_update_i_disksize(struct page *page,
2629                                             unsigned long offset)
2630 {
2631         struct buffer_head *bh;
2632         struct inode *inode = page->mapping->host;
2633         unsigned int idx;
2634         int i;
2635
2636         bh = page_buffers(page);
2637         idx = offset >> inode->i_blkbits;
2638
2639         for (i = 0; i < idx; i++)
2640                 bh = bh->b_this_page;
2641
2642         if (!buffer_mapped(bh) || (buffer_delay(bh)) || buffer_unwritten(bh))
2643                 return 0;
2644         return 1;
2645 }
2646
2647 static int ext4_da_write_end(struct file *file,
2648                              struct address_space *mapping,
2649                              loff_t pos, unsigned len, unsigned copied,
2650                              struct page *page, void *fsdata)
2651 {
2652         struct inode *inode = mapping->host;
2653         int ret = 0, ret2;
2654         handle_t *handle = ext4_journal_current_handle();
2655         loff_t new_i_size;
2656         unsigned long start, end;
2657         int write_mode = (int)(unsigned long)fsdata;
2658
2659         if (write_mode == FALL_BACK_TO_NONDELALLOC) {
2660                 switch (ext4_inode_journal_mode(inode)) {
2661                 case EXT4_INODE_ORDERED_DATA_MODE:
2662                         return ext4_ordered_write_end(file, mapping, pos,
2663                                         len, copied, page, fsdata);
2664                 case EXT4_INODE_WRITEBACK_DATA_MODE:
2665                         return ext4_writeback_write_end(file, mapping, pos,
2666                                         len, copied, page, fsdata);
2667                 default:
2668                         BUG();
2669                 }
2670         }
2671
2672         trace_ext4_da_write_end(inode, pos, len, copied);
2673         start = pos & (PAGE_CACHE_SIZE - 1);
2674         end = start + copied - 1;
2675
2676         /*
2677          * generic_write_end() will run mark_inode_dirty() if i_size
2678          * changes.  So let's piggyback the i_disksize mark_inode_dirty
2679          * into that.
2680          */
2681         new_i_size = pos + copied;
2682         if (copied && new_i_size > EXT4_I(inode)->i_disksize) {
2683                 if (ext4_has_inline_data(inode) ||
2684                     ext4_da_should_update_i_disksize(page, end)) {
2685                         down_write(&EXT4_I(inode)->i_data_sem);
2686                         if (new_i_size > EXT4_I(inode)->i_disksize)
2687                                 EXT4_I(inode)->i_disksize = new_i_size;
2688                         up_write(&EXT4_I(inode)->i_data_sem);
2689                         /* We need to mark inode dirty even if
2690                          * new_i_size is less that inode->i_size
2691                          * bu greater than i_disksize.(hint delalloc)
2692                          */
2693                         ext4_mark_inode_dirty(handle, inode);
2694                 }
2695         }
2696
2697         if (write_mode != CONVERT_INLINE_DATA &&
2698             ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA) &&
2699             ext4_has_inline_data(inode))
2700                 ret2 = ext4_da_write_inline_data_end(inode, pos, len, copied,
2701                                                      page);
2702         else
2703                 ret2 = generic_write_end(file, mapping, pos, len, copied,
2704                                                         page, fsdata);
2705
2706         copied = ret2;
2707         if (ret2 < 0)
2708                 ret = ret2;
2709         ret2 = ext4_journal_stop(handle);
2710         if (!ret)
2711                 ret = ret2;
2712
2713         return ret ? ret : copied;
2714 }
2715
2716 static void ext4_da_invalidatepage(struct page *page, unsigned long offset)
2717 {
2718         /*
2719          * Drop reserved blocks
2720          */
2721         BUG_ON(!PageLocked(page));
2722         if (!page_has_buffers(page))
2723                 goto out;
2724
2725         ext4_da_page_release_reservation(page, offset);
2726
2727 out:
2728         ext4_invalidatepage(page, offset);
2729
2730         return;
2731 }
2732
2733 /*
2734  * Force all delayed allocation blocks to be allocated for a given inode.
2735  */
2736 int ext4_alloc_da_blocks(struct inode *inode)
2737 {
2738         trace_ext4_alloc_da_blocks(inode);
2739
2740         if (!EXT4_I(inode)->i_reserved_data_blocks &&
2741             !EXT4_I(inode)->i_reserved_meta_blocks)
2742                 return 0;
2743
2744         /*
2745          * We do something simple for now.  The filemap_flush() will
2746          * also start triggering a write of the data blocks, which is
2747          * not strictly speaking necessary (and for users of
2748          * laptop_mode, not even desirable).  However, to do otherwise
2749          * would require replicating code paths in:
2750          *
2751          * ext4_da_writepages() ->
2752          *    write_cache_pages() ---> (via passed in callback function)
2753          *        __mpage_da_writepage() -->
2754          *           mpage_add_bh_to_extent()
2755          *           mpage_da_map_blocks()
2756          *
2757          * The problem is that write_cache_pages(), located in
2758          * mm/page-writeback.c, marks pages clean in preparation for
2759          * doing I/O, which is not desirable if we're not planning on
2760          * doing I/O at all.
2761          *
2762          * We could call write_cache_pages(), and then redirty all of
2763          * the pages by calling redirty_page_for_writepage() but that
2764          * would be ugly in the extreme.  So instead we would need to
2765          * replicate parts of the code in the above functions,
2766          * simplifying them because we wouldn't actually intend to
2767          * write out the pages, but rather only collect contiguous
2768          * logical block extents, call the multi-block allocator, and
2769          * then update the buffer heads with the block allocations.
2770          *
2771          * For now, though, we'll cheat by calling filemap_flush(),
2772          * which will map the blocks, and start the I/O, but not
2773          * actually wait for the I/O to complete.
2774          */
2775         return filemap_flush(inode->i_mapping);
2776 }
2777
2778 /*
2779  * bmap() is special.  It gets used by applications such as lilo and by
2780  * the swapper to find the on-disk block of a specific piece of data.
2781  *
2782  * Naturally, this is dangerous if the block concerned is still in the
2783  * journal.  If somebody makes a swapfile on an ext4 data-journaling
2784  * filesystem and enables swap, then they may get a nasty shock when the
2785  * data getting swapped to that swapfile suddenly gets overwritten by
2786  * the original zero's written out previously to the journal and
2787  * awaiting writeback in the kernel's buffer cache.
2788  *
2789  * So, if we see any bmap calls here on a modified, data-journaled file,
2790  * take extra steps to flush any blocks which might be in the cache.
2791  */
2792 static sector_t ext4_bmap(struct address_space *mapping, sector_t block)
2793 {
2794         struct inode *inode = mapping->host;
2795         journal_t *journal;
2796         int err;
2797
2798         /*
2799          * We can get here for an inline file via the FIBMAP ioctl
2800          */
2801         if (ext4_has_inline_data(inode))
2802                 return 0;
2803
2804         if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY) &&
2805                         test_opt(inode->i_sb, DELALLOC)) {
2806                 /*
2807                  * With delalloc we want to sync the file
2808                  * so that we can make sure we allocate
2809                  * blocks for file
2810                  */
2811                 filemap_write_and_wait(mapping);
2812         }
2813
2814         if (EXT4_JOURNAL(inode) &&
2815             ext4_test_inode_state(inode, EXT4_STATE_JDATA)) {
2816                 /*
2817                  * This is a REALLY heavyweight approach, but the use of
2818                  * bmap on dirty files is expected to be extremely rare:
2819                  * only if we run lilo or swapon on a freshly made file
2820                  * do we expect this to happen.
2821                  *
2822                  * (bmap requires CAP_SYS_RAWIO so this does not
2823                  * represent an unprivileged user DOS attack --- we'd be
2824                  * in trouble if mortal users could trigger this path at
2825                  * will.)
2826                  *
2827                  * NB. EXT4_STATE_JDATA is not set on files other than
2828                  * regular files.  If somebody wants to bmap a directory
2829                  * or symlink and gets confused because the buffer
2830                  * hasn't yet been flushed to disk, they deserve
2831                  * everything they get.
2832                  */
2833
2834                 ext4_clear_inode_state(inode, EXT4_STATE_JDATA);
2835                 journal = EXT4_JOURNAL(inode);
2836                 jbd2_journal_lock_updates(journal);
2837                 err = jbd2_journal_flush(journal);
2838                 jbd2_journal_unlock_updates(journal);
2839
2840                 if (err)
2841                         return 0;
2842         }
2843
2844         return generic_block_bmap(mapping, block, ext4_get_block);
2845 }
2846
2847 static int ext4_readpage(struct file *file, struct page *page)
2848 {
2849         int ret = -EAGAIN;
2850         struct inode *inode = page->mapping->host;
2851
2852         trace_ext4_readpage(page);
2853
2854         if (ext4_has_inline_data(inode))
2855                 ret = ext4_readpage_inline(inode, page);
2856
2857         if (ret == -EAGAIN)
2858                 return mpage_readpage(page, ext4_get_block);
2859
2860         return ret;
2861 }
2862
2863 static int
2864 ext4_readpages(struct file *file, struct address_space *mapping,
2865                 struct list_head *pages, unsigned nr_pages)
2866 {
2867         struct inode *inode = mapping->host;
2868
2869         /* If the file has inline data, no need to do readpages. */
2870         if (ext4_has_inline_data(inode))
2871                 return 0;
2872
2873         return mpage_readpages(mapping, pages, nr_pages, ext4_get_block);
2874 }
2875
2876 static void ext4_invalidatepage(struct page *page, unsigned long offset)
2877 {
2878         trace_ext4_invalidatepage(page, offset);
2879
2880         /* No journalling happens on data buffers when this function is used */
2881         WARN_ON(page_has_buffers(page) && buffer_jbd(page_buffers(page)));
2882
2883         block_invalidatepage(page, offset);
2884 }
2885
2886 static int __ext4_journalled_invalidatepage(struct page *page,
2887                                             unsigned long offset)
2888 {
2889         journal_t *journal = EXT4_JOURNAL(page->mapping->host);
2890
2891         trace_ext4_journalled_invalidatepage(page, offset);
2892
2893         /*
2894          * If it's a full truncate we just forget about the pending dirtying
2895          */
2896         if (offset == 0)
2897                 ClearPageChecked(page);
2898
2899         return jbd2_journal_invalidatepage(journal, page, offset);
2900 }
2901
2902 /* Wrapper for aops... */
2903 static void ext4_journalled_invalidatepage(struct page *page,
2904                                            unsigned long offset)
2905 {
2906         WARN_ON(__ext4_journalled_invalidatepage(page, offset) < 0);
2907 }
2908
2909 static int ext4_releasepage(struct page *page, gfp_t wait)
2910 {
2911         journal_t *journal = EXT4_JOURNAL(page->mapping->host);
2912
2913         trace_ext4_releasepage(page);
2914
2915         WARN_ON(PageChecked(page));
2916         if (!page_has_buffers(page))
2917                 return 0;
2918         if (journal)
2919                 return jbd2_journal_try_to_free_buffers(journal, page, wait);
2920         else
2921                 return try_to_free_buffers(page);
2922 }
2923
2924 /*
2925  * ext4_get_block used when preparing for a DIO write or buffer write.
2926  * We allocate an uinitialized extent if blocks haven't been allocated.
2927  * The extent will be converted to initialized after the IO is complete.
2928  */
2929 int ext4_get_block_write(struct inode *inode, sector_t iblock,
2930                    struct buffer_head *bh_result, int create)
2931 {
2932         ext4_debug("ext4_get_block_write: inode %lu, create flag %d\n",
2933                    inode->i_ino, create);
2934         return _ext4_get_block(inode, iblock, bh_result,
2935                                EXT4_GET_BLOCKS_IO_CREATE_EXT);
2936 }
2937
2938 static int ext4_get_block_write_nolock(struct inode *inode, sector_t iblock,
2939                    struct buffer_head *bh_result, int create)
2940 {
2941         ext4_debug("ext4_get_block_write_nolock: inode %lu, create flag %d\n",
2942                    inode->i_ino, create);
2943         return _ext4_get_block(inode, iblock, bh_result,
2944                                EXT4_GET_BLOCKS_NO_LOCK);
2945 }
2946
2947 static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
2948                             ssize_t size, void *private, int ret,
2949                             bool is_async)
2950 {
2951         struct inode *inode = iocb->ki_filp->f_path.dentry->d_inode;
2952         ext4_io_end_t *io_end = iocb->private;
2953
2954         /* if not async direct IO or dio with 0 bytes write, just return */
2955         if (!io_end || !size)
2956                 goto out;
2957
2958         ext_debug("ext4_end_io_dio(): io_end 0x%p "
2959                   "for inode %lu, iocb 0x%p, offset %llu, size %zd\n",
2960                   iocb->private, io_end->inode->i_ino, iocb, offset,
2961                   size);
2962
2963         iocb->private = NULL;
2964
2965         /* if not aio dio with unwritten extents, just free io and return */
2966         if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
2967                 ext4_free_io_end(io_end);
2968 out:
2969                 inode_dio_done(inode);
2970                 if (is_async)
2971                         aio_complete(iocb, ret, 0);
2972                 return;
2973         }
2974
2975         io_end->offset = offset;
2976         io_end->size = size;
2977         if (is_async) {
2978                 io_end->iocb = iocb;
2979                 io_end->result = ret;
2980         }
2981
2982         ext4_add_complete_io(io_end);
2983 }
2984
2985 /*
2986  * For ext4 extent files, ext4 will do direct-io write to holes,
2987  * preallocated extents, and those write extend the file, no need to
2988  * fall back to buffered IO.
2989  *
2990  * For holes, we fallocate those blocks, mark them as uninitialized
2991  * If those blocks were preallocated, we mark sure they are split, but
2992  * still keep the range to write as uninitialized.
2993  *
2994  * The unwritten extents will be converted to written when DIO is completed.
2995  * For async direct IO, since the IO may still pending when return, we
2996  * set up an end_io call back function, which will do the conversion
2997  * when async direct IO completed.
2998  *
2999  * If the O_DIRECT write will extend the file then add this inode to the
3000  * orphan list.  So recovery will truncate it back to the original size
3001  * if the machine crashes during the write.
3002  *
3003  */
3004 static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
3005                               const struct iovec *iov, loff_t offset,
3006                               unsigned long nr_segs)
3007 {
3008         struct file *file = iocb->ki_filp;
3009         struct inode *inode = file->f_mapping->host;
3010         ssize_t ret;
3011         size_t count = iov_length(iov, nr_segs);
3012         int overwrite = 0;
3013         get_block_t *get_block_func = NULL;
3014         int dio_flags = 0;
3015         loff_t final_size = offset + count;
3016
3017         /* Use the old path for reads and writes beyond i_size. */
3018         if (rw != WRITE || final_size > inode->i_size)
3019                 return ext4_ind_direct_IO(rw, iocb, iov, offset, nr_segs);
3020
3021         BUG_ON(iocb->private == NULL);
3022
3023         /* If we do a overwrite dio, i_mutex locking can be released */
3024         overwrite = *((int *)iocb->private);
3025
3026         if (overwrite) {
3027                 atomic_inc(&inode->i_dio_count);
3028                 down_read(&EXT4_I(inode)->i_data_sem);
3029                 mutex_unlock(&inode->i_mutex);
3030         }
3031
3032         /*
3033          * We could direct write to holes and fallocate.
3034          *
3035          * Allocated blocks to fill the hole are marked as
3036          * uninitialized to prevent parallel buffered read to expose
3037          * the stale data before DIO complete the data IO.
3038          *
3039          * As to previously fallocated extents, ext4 get_block will
3040          * just simply mark the buffer mapped but still keep the
3041          * extents uninitialized.
3042          *
3043          * For non AIO case, we will convert those unwritten extents
3044          * to written after return back from blockdev_direct_IO.
3045          *
3046          * For async DIO, the conversion needs to be deferred when the
3047          * IO is completed. The ext4 end_io callback function will be
3048          * called to take care of the conversion work.  Here for async
3049          * case, we allocate an io_end structure to hook to the iocb.
3050          */
3051         iocb->private = NULL;
3052         ext4_inode_aio_set(inode, NULL);
3053         if (!is_sync_kiocb(iocb)) {
3054                 ext4_io_end_t *io_end = ext4_init_io_end(inode, GFP_NOFS);
3055                 if (!io_end) {
3056                         ret = -ENOMEM;
3057                         goto retake_lock;
3058                 }
3059                 io_end->flag |= EXT4_IO_END_DIRECT;
3060                 iocb->private = io_end;
3061                 /*
3062                  * we save the io structure for current async direct
3063                  * IO, so that later ext4_map_blocks() could flag the
3064                  * io structure whether there is a unwritten extents
3065                  * needs to be converted when IO is completed.
3066                  */
3067                 ext4_inode_aio_set(inode, io_end);
3068         }
3069
3070         if (overwrite) {
3071                 get_block_func = ext4_get_block_write_nolock;
3072         } else {
3073                 get_block_func = ext4_get_block_write;
3074                 dio_flags = DIO_LOCKING;
3075         }
3076         ret = __blockdev_direct_IO(rw, iocb, inode,
3077                                    inode->i_sb->s_bdev, iov,
3078                                    offset, nr_segs,
3079                                    get_block_func,
3080                                    ext4_end_io_dio,
3081                                    NULL,
3082                                    dio_flags);
3083
3084         if (iocb->private)
3085                 ext4_inode_aio_set(inode, NULL);
3086         /*
3087          * The io_end structure takes a reference to the inode, that
3088          * structure needs to be destroyed and the reference to the
3089          * inode need to be dropped, when IO is complete, even with 0
3090          * byte write, or failed.
3091          *
3092          * In the successful AIO DIO case, the io_end structure will
3093          * be destroyed and the reference to the inode will be dropped
3094          * after the end_io call back function is called.
3095          *
3096          * In the case there is 0 byte write, or error case, since VFS
3097          * direct IO won't invoke the end_io call back function, we
3098          * need to free the end_io structure here.
3099          */
3100         if (ret != -EIOCBQUEUED && ret <= 0 && iocb->private) {
3101                 ext4_free_io_end(iocb->private);
3102                 iocb->private = NULL;
3103         } else if (ret > 0 && !overwrite && ext4_test_inode_state(inode,
3104                                                 EXT4_STATE_DIO_UNWRITTEN)) {
3105                 int err;
3106                 /*
3107                  * for non AIO case, since the IO is already
3108                  * completed, we could do the conversion right here
3109                  */
3110                 err = ext4_convert_unwritten_extents(inode,
3111                                                      offset, ret);
3112                 if (err < 0)
3113                         ret = err;
3114                 ext4_clear_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN);
3115         }
3116
3117 retake_lock:
3118         /* take i_mutex locking again if we do a ovewrite dio */
3119         if (overwrite) {
3120                 inode_dio_done(inode);
3121                 up_read(&EXT4_I(inode)->i_data_sem);
3122                 mutex_lock(&inode->i_mutex);
3123         }
3124
3125         return ret;
3126 }
3127
3128 static ssize_t ext4_direct_IO(int rw, struct kiocb *iocb,
3129                               const struct iovec *iov, loff_t offset,
3130                               unsigned long nr_segs)
3131 {
3132         struct file *file = iocb->ki_filp;
3133         struct inode *inode = file->f_mapping->host;
3134         ssize_t ret;
3135
3136         /*
3137          * If we are doing data journalling we don't support O_DIRECT
3138          */
3139         if (ext4_should_journal_data(inode))
3140                 return 0;
3141
3142         /* Let buffer I/O handle the inline data case. */
3143         if (ext4_has_inline_data(inode))
3144                 return 0;
3145
3146         trace_ext4_direct_IO_enter(inode, offset, iov_length(iov, nr_segs), rw);
3147         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
3148                 ret = ext4_ext_direct_IO(rw, iocb, iov, offset, nr_segs);
3149         else
3150                 ret = ext4_ind_direct_IO(rw, iocb, iov, offset, nr_segs);
3151         trace_ext4_direct_IO_exit(inode, offset,
3152                                 iov_length(iov, nr_segs), rw, ret);
3153         return ret;
3154 }
3155
3156 /*
3157  * Pages can be marked dirty completely asynchronously from ext4's journalling
3158  * activity.  By filemap_sync_pte(), try_to_unmap_one(), etc.  We cannot do
3159  * much here because ->set_page_dirty is called under VFS locks.  The page is
3160  * not necessarily locked.
3161  *
3162  * We cannot just dirty the page and leave attached buffers clean, because the
3163  * buffers' dirty state is "definitive".  We cannot just set the buffers dirty
3164  * or jbddirty because all the journalling code will explode.
3165  *
3166  * So what we do is to mark the page "pending dirty" and next time writepage
3167  * is called, propagate that into the buffers appropriately.
3168  */
3169 static int ext4_journalled_set_page_dirty(struct page *page)
3170 {
3171         SetPageChecked(page);
3172         return __set_page_dirty_nobuffers(page);
3173 }
3174
3175 static const struct address_space_operations ext4_ordered_aops = {
3176         .readpage               = ext4_readpage,
3177         .readpages              = ext4_readpages,
3178         .writepage              = ext4_writepage,
3179         .write_begin            = ext4_write_begin,
3180         .write_end              = ext4_ordered_write_end,
3181         .bmap                   = ext4_bmap,
3182         .invalidatepage         = ext4_invalidatepage,
3183         .releasepage            = ext4_releasepage,
3184         .direct_IO              = ext4_direct_IO,
3185         .migratepage            = buffer_migrate_page,
3186         .is_partially_uptodate  = block_is_partially_uptodate,
3187         .error_remove_page      = generic_error_remove_page,
3188 };
3189
3190 static const struct address_space_operations ext4_writeback_aops = {
3191         .readpage               = ext4_readpage,
3192         .readpages              = ext4_readpages,
3193         .writepage              = ext4_writepage,
3194         .write_begin            = ext4_write_begin,
3195         .write_end              = ext4_writeback_write_end,
3196         .bmap                   = ext4_bmap,
3197         .invalidatepage         = ext4_invalidatepage,
3198         .releasepage            = ext4_releasepage,
3199         .direct_IO              = ext4_direct_IO,
3200         .migratepage            = buffer_migrate_page,
3201         .is_partially_uptodate  = block_is_partially_uptodate,
3202         .error_remove_page      = generic_error_remove_page,
3203 };
3204
3205 static const struct address_space_operations ext4_journalled_aops = {
3206         .readpage               = ext4_readpage,
3207         .readpages              = ext4_readpages,
3208         .writepage              = ext4_writepage,
3209         .write_begin            = ext4_write_begin,
3210         .write_end              = ext4_journalled_write_end,
3211         .set_page_dirty         = ext4_journalled_set_page_dirty,
3212         .bmap                   = ext4_bmap,
3213         .invalidatepage         = ext4_journalled_invalidatepage,
3214         .releasepage            = ext4_releasepage,
3215         .direct_IO              = ext4_direct_IO,
3216         .is_partially_uptodate  = block_is_partially_uptodate,
3217         .error_remove_page      = generic_error_remove_page,
3218 };
3219
3220 static const struct address_space_operations ext4_da_aops = {
3221         .readpage               = ext4_readpage,
3222         .readpages              = ext4_readpages,
3223         .writepage              = ext4_writepage,
3224         .writepages             = ext4_da_writepages,
3225         .write_begin            = ext4_da_write_begin,
3226         .write_end              = ext4_da_write_end,