859ba2dd88903ba207c7b0e448e0f5ce7f99e46e
[~shefty/rdma-dev.git] / fs / btrfs / file.c
1 /*
2  * Copyright (C) 2007 Oracle.  All rights reserved.
3  *
4  * This program is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU General Public
6  * License v2 as published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope that it will be useful,
9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
11  * General Public License for more details.
12  *
13  * You should have received a copy of the GNU General Public
14  * License along with this program; if not, write to the
15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16  * Boston, MA 021110-1307, USA.
17  */
18
19 #include <linux/fs.h>
20 #include <linux/pagemap.h>
21 #include <linux/highmem.h>
22 #include <linux/time.h>
23 #include <linux/init.h>
24 #include <linux/string.h>
25 #include <linux/backing-dev.h>
26 #include <linux/mpage.h>
27 #include <linux/falloc.h>
28 #include <linux/swap.h>
29 #include <linux/writeback.h>
30 #include <linux/statfs.h>
31 #include <linux/compat.h>
32 #include <linux/slab.h>
33 #include "ctree.h"
34 #include "disk-io.h"
35 #include "transaction.h"
36 #include "btrfs_inode.h"
37 #include "ioctl.h"
38 #include "print-tree.h"
39 #include "tree-log.h"
40 #include "locking.h"
41 #include "compat.h"
42
43 /*
44  * when auto defrag is enabled we
45  * queue up these defrag structs to remember which
46  * inodes need defragging passes
47  */
48 struct inode_defrag {
49         struct rb_node rb_node;
50         /* objectid */
51         u64 ino;
52         /*
53          * transid where the defrag was added, we search for
54          * extents newer than this
55          */
56         u64 transid;
57
58         /* root objectid */
59         u64 root;
60
61         /* last offset we were able to defrag */
62         u64 last_offset;
63
64         /* if we've wrapped around back to zero once already */
65         int cycled;
66 };
67
68 /* pop a record for an inode into the defrag tree.  The lock
69  * must be held already
70  *
71  * If you're inserting a record for an older transid than an
72  * existing record, the transid already in the tree is lowered
73  *
74  * If an existing record is found the defrag item you
75  * pass in is freed
76  */
77 static void __btrfs_add_inode_defrag(struct inode *inode,
78                                     struct inode_defrag *defrag)
79 {
80         struct btrfs_root *root = BTRFS_I(inode)->root;
81         struct inode_defrag *entry;
82         struct rb_node **p;
83         struct rb_node *parent = NULL;
84
85         p = &root->fs_info->defrag_inodes.rb_node;
86         while (*p) {
87                 parent = *p;
88                 entry = rb_entry(parent, struct inode_defrag, rb_node);
89
90                 if (defrag->ino < entry->ino)
91                         p = &parent->rb_left;
92                 else if (defrag->ino > entry->ino)
93                         p = &parent->rb_right;
94                 else {
95                         /* if we're reinserting an entry for
96                          * an old defrag run, make sure to
97                          * lower the transid of our existing record
98                          */
99                         if (defrag->transid < entry->transid)
100                                 entry->transid = defrag->transid;
101                         if (defrag->last_offset > entry->last_offset)
102                                 entry->last_offset = defrag->last_offset;
103                         goto exists;
104                 }
105         }
106         BTRFS_I(inode)->in_defrag = 1;
107         rb_link_node(&defrag->rb_node, parent, p);
108         rb_insert_color(&defrag->rb_node, &root->fs_info->defrag_inodes);
109         return;
110
111 exists:
112         kfree(defrag);
113         return;
114
115 }
116
117 /*
118  * insert a defrag record for this inode if auto defrag is
119  * enabled
120  */
121 int btrfs_add_inode_defrag(struct btrfs_trans_handle *trans,
122                            struct inode *inode)
123 {
124         struct btrfs_root *root = BTRFS_I(inode)->root;
125         struct inode_defrag *defrag;
126         u64 transid;
127
128         if (!btrfs_test_opt(root, AUTO_DEFRAG))
129                 return 0;
130
131         if (btrfs_fs_closing(root->fs_info))
132                 return 0;
133
134         if (BTRFS_I(inode)->in_defrag)
135                 return 0;
136
137         if (trans)
138                 transid = trans->transid;
139         else
140                 transid = BTRFS_I(inode)->root->last_trans;
141
142         defrag = kzalloc(sizeof(*defrag), GFP_NOFS);
143         if (!defrag)
144                 return -ENOMEM;
145
146         defrag->ino = btrfs_ino(inode);
147         defrag->transid = transid;
148         defrag->root = root->root_key.objectid;
149
150         spin_lock(&root->fs_info->defrag_inodes_lock);
151         if (!BTRFS_I(inode)->in_defrag)
152                 __btrfs_add_inode_defrag(inode, defrag);
153         else
154                 kfree(defrag);
155         spin_unlock(&root->fs_info->defrag_inodes_lock);
156         return 0;
157 }
158
159 /*
160  * must be called with the defrag_inodes lock held
161  */
162 struct inode_defrag *btrfs_find_defrag_inode(struct btrfs_fs_info *info, u64 ino,
163                                              struct rb_node **next)
164 {
165         struct inode_defrag *entry = NULL;
166         struct rb_node *p;
167         struct rb_node *parent = NULL;
168
169         p = info->defrag_inodes.rb_node;
170         while (p) {
171                 parent = p;
172                 entry = rb_entry(parent, struct inode_defrag, rb_node);
173
174                 if (ino < entry->ino)
175                         p = parent->rb_left;
176                 else if (ino > entry->ino)
177                         p = parent->rb_right;
178                 else
179                         return entry;
180         }
181
182         if (next) {
183                 while (parent && ino > entry->ino) {
184                         parent = rb_next(parent);
185                         entry = rb_entry(parent, struct inode_defrag, rb_node);
186                 }
187                 *next = parent;
188         }
189         return NULL;
190 }
191
192 /*
193  * run through the list of inodes in the FS that need
194  * defragging
195  */
196 int btrfs_run_defrag_inodes(struct btrfs_fs_info *fs_info)
197 {
198         struct inode_defrag *defrag;
199         struct btrfs_root *inode_root;
200         struct inode *inode;
201         struct rb_node *n;
202         struct btrfs_key key;
203         struct btrfs_ioctl_defrag_range_args range;
204         u64 first_ino = 0;
205         int num_defrag;
206         int defrag_batch = 1024;
207
208         memset(&range, 0, sizeof(range));
209         range.len = (u64)-1;
210
211         atomic_inc(&fs_info->defrag_running);
212         spin_lock(&fs_info->defrag_inodes_lock);
213         while(1) {
214                 n = NULL;
215
216                 /* find an inode to defrag */
217                 defrag = btrfs_find_defrag_inode(fs_info, first_ino, &n);
218                 if (!defrag) {
219                         if (n)
220                                 defrag = rb_entry(n, struct inode_defrag, rb_node);
221                         else if (first_ino) {
222                                 first_ino = 0;
223                                 continue;
224                         } else {
225                                 break;
226                         }
227                 }
228
229                 /* remove it from the rbtree */
230                 first_ino = defrag->ino + 1;
231                 rb_erase(&defrag->rb_node, &fs_info->defrag_inodes);
232
233                 if (btrfs_fs_closing(fs_info))
234                         goto next_free;
235
236                 spin_unlock(&fs_info->defrag_inodes_lock);
237
238                 /* get the inode */
239                 key.objectid = defrag->root;
240                 btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
241                 key.offset = (u64)-1;
242                 inode_root = btrfs_read_fs_root_no_name(fs_info, &key);
243                 if (IS_ERR(inode_root))
244                         goto next;
245
246                 key.objectid = defrag->ino;
247                 btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
248                 key.offset = 0;
249
250                 inode = btrfs_iget(fs_info->sb, &key, inode_root, NULL);
251                 if (IS_ERR(inode))
252                         goto next;
253
254                 /* do a chunk of defrag */
255                 BTRFS_I(inode)->in_defrag = 0;
256                 range.start = defrag->last_offset;
257                 num_defrag = btrfs_defrag_file(inode, NULL, &range, defrag->transid,
258                                                defrag_batch);
259                 /*
260                  * if we filled the whole defrag batch, there
261                  * must be more work to do.  Queue this defrag
262                  * again
263                  */
264                 if (num_defrag == defrag_batch) {
265                         defrag->last_offset = range.start;
266                         __btrfs_add_inode_defrag(inode, defrag);
267                         /*
268                          * we don't want to kfree defrag, we added it back to
269                          * the rbtree
270                          */
271                         defrag = NULL;
272                 } else if (defrag->last_offset && !defrag->cycled) {
273                         /*
274                          * we didn't fill our defrag batch, but
275                          * we didn't start at zero.  Make sure we loop
276                          * around to the start of the file.
277                          */
278                         defrag->last_offset = 0;
279                         defrag->cycled = 1;
280                         __btrfs_add_inode_defrag(inode, defrag);
281                         defrag = NULL;
282                 }
283
284                 iput(inode);
285 next:
286                 spin_lock(&fs_info->defrag_inodes_lock);
287 next_free:
288                 kfree(defrag);
289         }
290         spin_unlock(&fs_info->defrag_inodes_lock);
291
292         atomic_dec(&fs_info->defrag_running);
293
294         /*
295          * during unmount, we use the transaction_wait queue to
296          * wait for the defragger to stop
297          */
298         wake_up(&fs_info->transaction_wait);
299         return 0;
300 }
301
302 /* simple helper to fault in pages and copy.  This should go away
303  * and be replaced with calls into generic code.
304  */
305 static noinline int btrfs_copy_from_user(loff_t pos, int num_pages,
306                                          size_t write_bytes,
307                                          struct page **prepared_pages,
308                                          struct iov_iter *i)
309 {
310         size_t copied = 0;
311         size_t total_copied = 0;
312         int pg = 0;
313         int offset = pos & (PAGE_CACHE_SIZE - 1);
314
315         while (write_bytes > 0) {
316                 size_t count = min_t(size_t,
317                                      PAGE_CACHE_SIZE - offset, write_bytes);
318                 struct page *page = prepared_pages[pg];
319                 /*
320                  * Copy data from userspace to the current page
321                  *
322                  * Disable pagefault to avoid recursive lock since
323                  * the pages are already locked
324                  */
325                 pagefault_disable();
326                 copied = iov_iter_copy_from_user_atomic(page, i, offset, count);
327                 pagefault_enable();
328
329                 /* Flush processor's dcache for this page */
330                 flush_dcache_page(page);
331
332                 /*
333                  * if we get a partial write, we can end up with
334                  * partially up to date pages.  These add
335                  * a lot of complexity, so make sure they don't
336                  * happen by forcing this copy to be retried.
337                  *
338                  * The rest of the btrfs_file_write code will fall
339                  * back to page at a time copies after we return 0.
340                  */
341                 if (!PageUptodate(page) && copied < count)
342                         copied = 0;
343
344                 iov_iter_advance(i, copied);
345                 write_bytes -= copied;
346                 total_copied += copied;
347
348                 /* Return to btrfs_file_aio_write to fault page */
349                 if (unlikely(copied == 0))
350                         break;
351
352                 if (unlikely(copied < PAGE_CACHE_SIZE - offset)) {
353                         offset += copied;
354                 } else {
355                         pg++;
356                         offset = 0;
357                 }
358         }
359         return total_copied;
360 }
361
362 /*
363  * unlocks pages after btrfs_file_write is done with them
364  */
365 void btrfs_drop_pages(struct page **pages, size_t num_pages)
366 {
367         size_t i;
368         for (i = 0; i < num_pages; i++) {
369                 /* page checked is some magic around finding pages that
370                  * have been modified without going through btrfs_set_page_dirty
371                  * clear it here
372                  */
373                 ClearPageChecked(pages[i]);
374                 unlock_page(pages[i]);
375                 mark_page_accessed(pages[i]);
376                 page_cache_release(pages[i]);
377         }
378 }
379
380 /*
381  * after copy_from_user, pages need to be dirtied and we need to make
382  * sure holes are created between the current EOF and the start of
383  * any next extents (if required).
384  *
385  * this also makes the decision about creating an inline extent vs
386  * doing real data extents, marking pages dirty and delalloc as required.
387  */
388 int btrfs_dirty_pages(struct btrfs_root *root, struct inode *inode,
389                       struct page **pages, size_t num_pages,
390                       loff_t pos, size_t write_bytes,
391                       struct extent_state **cached)
392 {
393         int err = 0;
394         int i;
395         u64 num_bytes;
396         u64 start_pos;
397         u64 end_of_last_block;
398         u64 end_pos = pos + write_bytes;
399         loff_t isize = i_size_read(inode);
400
401         start_pos = pos & ~((u64)root->sectorsize - 1);
402         num_bytes = (write_bytes + pos - start_pos +
403                     root->sectorsize - 1) & ~((u64)root->sectorsize - 1);
404
405         end_of_last_block = start_pos + num_bytes - 1;
406         err = btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block,
407                                         cached);
408         if (err)
409                 return err;
410
411         for (i = 0; i < num_pages; i++) {
412                 struct page *p = pages[i];
413                 SetPageUptodate(p);
414                 ClearPageChecked(p);
415                 set_page_dirty(p);
416         }
417
418         /*
419          * we've only changed i_size in ram, and we haven't updated
420          * the disk i_size.  There is no need to log the inode
421          * at this time.
422          */
423         if (end_pos > isize)
424                 i_size_write(inode, end_pos);
425         return 0;
426 }
427
428 /*
429  * this drops all the extents in the cache that intersect the range
430  * [start, end].  Existing extents are split as required.
431  */
432 int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
433                             int skip_pinned)
434 {
435         struct extent_map *em;
436         struct extent_map *split = NULL;
437         struct extent_map *split2 = NULL;
438         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
439         u64 len = end - start + 1;
440         int ret;
441         int testend = 1;
442         unsigned long flags;
443         int compressed = 0;
444
445         WARN_ON(end < start);
446         if (end == (u64)-1) {
447                 len = (u64)-1;
448                 testend = 0;
449         }
450         while (1) {
451                 if (!split)
452                         split = alloc_extent_map();
453                 if (!split2)
454                         split2 = alloc_extent_map();
455                 BUG_ON(!split || !split2);
456
457                 write_lock(&em_tree->lock);
458                 em = lookup_extent_mapping(em_tree, start, len);
459                 if (!em) {
460                         write_unlock(&em_tree->lock);
461                         break;
462                 }
463                 flags = em->flags;
464                 if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
465                         if (testend && em->start + em->len >= start + len) {
466                                 free_extent_map(em);
467                                 write_unlock(&em_tree->lock);
468                                 break;
469                         }
470                         start = em->start + em->len;
471                         if (testend)
472                                 len = start + len - (em->start + em->len);
473                         free_extent_map(em);
474                         write_unlock(&em_tree->lock);
475                         continue;
476                 }
477                 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
478                 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
479                 remove_extent_mapping(em_tree, em);
480
481                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
482                     em->start < start) {
483                         split->start = em->start;
484                         split->len = start - em->start;
485                         split->orig_start = em->orig_start;
486                         split->block_start = em->block_start;
487
488                         if (compressed)
489                                 split->block_len = em->block_len;
490                         else
491                                 split->block_len = split->len;
492
493                         split->bdev = em->bdev;
494                         split->flags = flags;
495                         split->compress_type = em->compress_type;
496                         ret = add_extent_mapping(em_tree, split);
497                         BUG_ON(ret);
498                         free_extent_map(split);
499                         split = split2;
500                         split2 = NULL;
501                 }
502                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
503                     testend && em->start + em->len > start + len) {
504                         u64 diff = start + len - em->start;
505
506                         split->start = start + len;
507                         split->len = em->start + em->len - (start + len);
508                         split->bdev = em->bdev;
509                         split->flags = flags;
510                         split->compress_type = em->compress_type;
511
512                         if (compressed) {
513                                 split->block_len = em->block_len;
514                                 split->block_start = em->block_start;
515                                 split->orig_start = em->orig_start;
516                         } else {
517                                 split->block_len = split->len;
518                                 split->block_start = em->block_start + diff;
519                                 split->orig_start = split->start;
520                         }
521
522                         ret = add_extent_mapping(em_tree, split);
523                         BUG_ON(ret);
524                         free_extent_map(split);
525                         split = NULL;
526                 }
527                 write_unlock(&em_tree->lock);
528
529                 /* once for us */
530                 free_extent_map(em);
531                 /* once for the tree*/
532                 free_extent_map(em);
533         }
534         if (split)
535                 free_extent_map(split);
536         if (split2)
537                 free_extent_map(split2);
538         return 0;
539 }
540
541 /*
542  * this is very complex, but the basic idea is to drop all extents
543  * in the range start - end.  hint_block is filled in with a block number
544  * that would be a good hint to the block allocator for this file.
545  *
546  * If an extent intersects the range but is not entirely inside the range
547  * it is either truncated or split.  Anything entirely inside the range
548  * is deleted from the tree.
549  */
550 int btrfs_drop_extents(struct btrfs_trans_handle *trans, struct inode *inode,
551                        u64 start, u64 end, u64 *hint_byte, int drop_cache)
552 {
553         struct btrfs_root *root = BTRFS_I(inode)->root;
554         struct extent_buffer *leaf;
555         struct btrfs_file_extent_item *fi;
556         struct btrfs_path *path;
557         struct btrfs_key key;
558         struct btrfs_key new_key;
559         u64 ino = btrfs_ino(inode);
560         u64 search_start = start;
561         u64 disk_bytenr = 0;
562         u64 num_bytes = 0;
563         u64 extent_offset = 0;
564         u64 extent_end = 0;
565         int del_nr = 0;
566         int del_slot = 0;
567         int extent_type;
568         int recow;
569         int ret;
570
571         if (drop_cache)
572                 btrfs_drop_extent_cache(inode, start, end - 1, 0);
573
574         path = btrfs_alloc_path();
575         if (!path)
576                 return -ENOMEM;
577
578         while (1) {
579                 recow = 0;
580                 ret = btrfs_lookup_file_extent(trans, root, path, ino,
581                                                search_start, -1);
582                 if (ret < 0)
583                         break;
584                 if (ret > 0 && path->slots[0] > 0 && search_start == start) {
585                         leaf = path->nodes[0];
586                         btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
587                         if (key.objectid == ino &&
588                             key.type == BTRFS_EXTENT_DATA_KEY)
589                                 path->slots[0]--;
590                 }
591                 ret = 0;
592 next_slot:
593                 leaf = path->nodes[0];
594                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
595                         BUG_ON(del_nr > 0);
596                         ret = btrfs_next_leaf(root, path);
597                         if (ret < 0)
598                                 break;
599                         if (ret > 0) {
600                                 ret = 0;
601                                 break;
602                         }
603                         leaf = path->nodes[0];
604                         recow = 1;
605                 }
606
607                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
608                 if (key.objectid > ino ||
609                     key.type > BTRFS_EXTENT_DATA_KEY || key.offset >= end)
610                         break;
611
612                 fi = btrfs_item_ptr(leaf, path->slots[0],
613                                     struct btrfs_file_extent_item);
614                 extent_type = btrfs_file_extent_type(leaf, fi);
615
616                 if (extent_type == BTRFS_FILE_EXTENT_REG ||
617                     extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
618                         disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
619                         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
620                         extent_offset = btrfs_file_extent_offset(leaf, fi);
621                         extent_end = key.offset +
622                                 btrfs_file_extent_num_bytes(leaf, fi);
623                 } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
624                         extent_end = key.offset +
625                                 btrfs_file_extent_inline_len(leaf, fi);
626                 } else {
627                         WARN_ON(1);
628                         extent_end = search_start;
629                 }
630
631                 if (extent_end <= search_start) {
632                         path->slots[0]++;
633                         goto next_slot;
634                 }
635
636                 search_start = max(key.offset, start);
637                 if (recow) {
638                         btrfs_release_path(path);
639                         continue;
640                 }
641
642                 /*
643                  *     | - range to drop - |
644                  *  | -------- extent -------- |
645                  */
646                 if (start > key.offset && end < extent_end) {
647                         BUG_ON(del_nr > 0);
648                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
649
650                         memcpy(&new_key, &key, sizeof(new_key));
651                         new_key.offset = start;
652                         ret = btrfs_duplicate_item(trans, root, path,
653                                                    &new_key);
654                         if (ret == -EAGAIN) {
655                                 btrfs_release_path(path);
656                                 continue;
657                         }
658                         if (ret < 0)
659                                 break;
660
661                         leaf = path->nodes[0];
662                         fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
663                                             struct btrfs_file_extent_item);
664                         btrfs_set_file_extent_num_bytes(leaf, fi,
665                                                         start - key.offset);
666
667                         fi = btrfs_item_ptr(leaf, path->slots[0],
668                                             struct btrfs_file_extent_item);
669
670                         extent_offset += start - key.offset;
671                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
672                         btrfs_set_file_extent_num_bytes(leaf, fi,
673                                                         extent_end - start);
674                         btrfs_mark_buffer_dirty(leaf);
675
676                         if (disk_bytenr > 0) {
677                                 ret = btrfs_inc_extent_ref(trans, root,
678                                                 disk_bytenr, num_bytes, 0,
679                                                 root->root_key.objectid,
680                                                 new_key.objectid,
681                                                 start - extent_offset, 0);
682                                 BUG_ON(ret);
683                                 *hint_byte = disk_bytenr;
684                         }
685                         key.offset = start;
686                 }
687                 /*
688                  *  | ---- range to drop ----- |
689                  *      | -------- extent -------- |
690                  */
691                 if (start <= key.offset && end < extent_end) {
692                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
693
694                         memcpy(&new_key, &key, sizeof(new_key));
695                         new_key.offset = end;
696                         btrfs_set_item_key_safe(trans, root, path, &new_key);
697
698                         extent_offset += end - key.offset;
699                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
700                         btrfs_set_file_extent_num_bytes(leaf, fi,
701                                                         extent_end - end);
702                         btrfs_mark_buffer_dirty(leaf);
703                         if (disk_bytenr > 0) {
704                                 inode_sub_bytes(inode, end - key.offset);
705                                 *hint_byte = disk_bytenr;
706                         }
707                         break;
708                 }
709
710                 search_start = extent_end;
711                 /*
712                  *       | ---- range to drop ----- |
713                  *  | -------- extent -------- |
714                  */
715                 if (start > key.offset && end >= extent_end) {
716                         BUG_ON(del_nr > 0);
717                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
718
719                         btrfs_set_file_extent_num_bytes(leaf, fi,
720                                                         start - key.offset);
721                         btrfs_mark_buffer_dirty(leaf);
722                         if (disk_bytenr > 0) {
723                                 inode_sub_bytes(inode, extent_end - start);
724                                 *hint_byte = disk_bytenr;
725                         }
726                         if (end == extent_end)
727                                 break;
728
729                         path->slots[0]++;
730                         goto next_slot;
731                 }
732
733                 /*
734                  *  | ---- range to drop ----- |
735                  *    | ------ extent ------ |
736                  */
737                 if (start <= key.offset && end >= extent_end) {
738                         if (del_nr == 0) {
739                                 del_slot = path->slots[0];
740                                 del_nr = 1;
741                         } else {
742                                 BUG_ON(del_slot + del_nr != path->slots[0]);
743                                 del_nr++;
744                         }
745
746                         if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
747                                 inode_sub_bytes(inode,
748                                                 extent_end - key.offset);
749                                 extent_end = ALIGN(extent_end,
750                                                    root->sectorsize);
751                         } else if (disk_bytenr > 0) {
752                                 ret = btrfs_free_extent(trans, root,
753                                                 disk_bytenr, num_bytes, 0,
754                                                 root->root_key.objectid,
755                                                 key.objectid, key.offset -
756                                                 extent_offset, 0);
757                                 BUG_ON(ret);
758                                 inode_sub_bytes(inode,
759                                                 extent_end - key.offset);
760                                 *hint_byte = disk_bytenr;
761                         }
762
763                         if (end == extent_end)
764                                 break;
765
766                         if (path->slots[0] + 1 < btrfs_header_nritems(leaf)) {
767                                 path->slots[0]++;
768                                 goto next_slot;
769                         }
770
771                         ret = btrfs_del_items(trans, root, path, del_slot,
772                                               del_nr);
773                         BUG_ON(ret);
774
775                         del_nr = 0;
776                         del_slot = 0;
777
778                         btrfs_release_path(path);
779                         continue;
780                 }
781
782                 BUG_ON(1);
783         }
784
785         if (del_nr > 0) {
786                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
787                 BUG_ON(ret);
788         }
789
790         btrfs_free_path(path);
791         return ret;
792 }
793
794 static int extent_mergeable(struct extent_buffer *leaf, int slot,
795                             u64 objectid, u64 bytenr, u64 orig_offset,
796                             u64 *start, u64 *end)
797 {
798         struct btrfs_file_extent_item *fi;
799         struct btrfs_key key;
800         u64 extent_end;
801
802         if (slot < 0 || slot >= btrfs_header_nritems(leaf))
803                 return 0;
804
805         btrfs_item_key_to_cpu(leaf, &key, slot);
806         if (key.objectid != objectid || key.type != BTRFS_EXTENT_DATA_KEY)
807                 return 0;
808
809         fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
810         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG ||
811             btrfs_file_extent_disk_bytenr(leaf, fi) != bytenr ||
812             btrfs_file_extent_offset(leaf, fi) != key.offset - orig_offset ||
813             btrfs_file_extent_compression(leaf, fi) ||
814             btrfs_file_extent_encryption(leaf, fi) ||
815             btrfs_file_extent_other_encoding(leaf, fi))
816                 return 0;
817
818         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
819         if ((*start && *start != key.offset) || (*end && *end != extent_end))
820                 return 0;
821
822         *start = key.offset;
823         *end = extent_end;
824         return 1;
825 }
826
827 /*
828  * Mark extent in the range start - end as written.
829  *
830  * This changes extent type from 'pre-allocated' to 'regular'. If only
831  * part of extent is marked as written, the extent will be split into
832  * two or three.
833  */
834 int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
835                               struct inode *inode, u64 start, u64 end)
836 {
837         struct btrfs_root *root = BTRFS_I(inode)->root;
838         struct extent_buffer *leaf;
839         struct btrfs_path *path;
840         struct btrfs_file_extent_item *fi;
841         struct btrfs_key key;
842         struct btrfs_key new_key;
843         u64 bytenr;
844         u64 num_bytes;
845         u64 extent_end;
846         u64 orig_offset;
847         u64 other_start;
848         u64 other_end;
849         u64 split;
850         int del_nr = 0;
851         int del_slot = 0;
852         int recow;
853         int ret;
854         u64 ino = btrfs_ino(inode);
855
856         btrfs_drop_extent_cache(inode, start, end - 1, 0);
857
858         path = btrfs_alloc_path();
859         if (!path)
860                 return -ENOMEM;
861 again:
862         recow = 0;
863         split = start;
864         key.objectid = ino;
865         key.type = BTRFS_EXTENT_DATA_KEY;
866         key.offset = split;
867
868         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
869         if (ret < 0)
870                 goto out;
871         if (ret > 0 && path->slots[0] > 0)
872                 path->slots[0]--;
873
874         leaf = path->nodes[0];
875         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
876         BUG_ON(key.objectid != ino || key.type != BTRFS_EXTENT_DATA_KEY);
877         fi = btrfs_item_ptr(leaf, path->slots[0],
878                             struct btrfs_file_extent_item);
879         BUG_ON(btrfs_file_extent_type(leaf, fi) !=
880                BTRFS_FILE_EXTENT_PREALLOC);
881         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
882         BUG_ON(key.offset > start || extent_end < end);
883
884         bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
885         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
886         orig_offset = key.offset - btrfs_file_extent_offset(leaf, fi);
887         memcpy(&new_key, &key, sizeof(new_key));
888
889         if (start == key.offset && end < extent_end) {
890                 other_start = 0;
891                 other_end = start;
892                 if (extent_mergeable(leaf, path->slots[0] - 1,
893                                      ino, bytenr, orig_offset,
894                                      &other_start, &other_end)) {
895                         new_key.offset = end;
896                         btrfs_set_item_key_safe(trans, root, path, &new_key);
897                         fi = btrfs_item_ptr(leaf, path->slots[0],
898                                             struct btrfs_file_extent_item);
899                         btrfs_set_file_extent_num_bytes(leaf, fi,
900                                                         extent_end - end);
901                         btrfs_set_file_extent_offset(leaf, fi,
902                                                      end - orig_offset);
903                         fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
904                                             struct btrfs_file_extent_item);
905                         btrfs_set_file_extent_num_bytes(leaf, fi,
906                                                         end - other_start);
907                         btrfs_mark_buffer_dirty(leaf);
908                         goto out;
909                 }
910         }
911
912         if (start > key.offset && end == extent_end) {
913                 other_start = end;
914                 other_end = 0;
915                 if (extent_mergeable(leaf, path->slots[0] + 1,
916                                      ino, bytenr, orig_offset,
917                                      &other_start, &other_end)) {
918                         fi = btrfs_item_ptr(leaf, path->slots[0],
919                                             struct btrfs_file_extent_item);
920                         btrfs_set_file_extent_num_bytes(leaf, fi,
921                                                         start - key.offset);
922                         path->slots[0]++;
923                         new_key.offset = start;
924                         btrfs_set_item_key_safe(trans, root, path, &new_key);
925
926                         fi = btrfs_item_ptr(leaf, path->slots[0],
927                                             struct btrfs_file_extent_item);
928                         btrfs_set_file_extent_num_bytes(leaf, fi,
929                                                         other_end - start);
930                         btrfs_set_file_extent_offset(leaf, fi,
931                                                      start - orig_offset);
932                         btrfs_mark_buffer_dirty(leaf);
933                         goto out;
934                 }
935         }
936
937         while (start > key.offset || end < extent_end) {
938                 if (key.offset == start)
939                         split = end;
940
941                 new_key.offset = split;
942                 ret = btrfs_duplicate_item(trans, root, path, &new_key);
943                 if (ret == -EAGAIN) {
944                         btrfs_release_path(path);
945                         goto again;
946                 }
947                 BUG_ON(ret < 0);
948
949                 leaf = path->nodes[0];
950                 fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
951                                     struct btrfs_file_extent_item);
952                 btrfs_set_file_extent_num_bytes(leaf, fi,
953                                                 split - key.offset);
954
955                 fi = btrfs_item_ptr(leaf, path->slots[0],
956                                     struct btrfs_file_extent_item);
957
958                 btrfs_set_file_extent_offset(leaf, fi, split - orig_offset);
959                 btrfs_set_file_extent_num_bytes(leaf, fi,
960                                                 extent_end - split);
961                 btrfs_mark_buffer_dirty(leaf);
962
963                 ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes, 0,
964                                            root->root_key.objectid,
965                                            ino, orig_offset, 0);
966                 BUG_ON(ret);
967
968                 if (split == start) {
969                         key.offset = start;
970                 } else {
971                         BUG_ON(start != key.offset);
972                         path->slots[0]--;
973                         extent_end = end;
974                 }
975                 recow = 1;
976         }
977
978         other_start = end;
979         other_end = 0;
980         if (extent_mergeable(leaf, path->slots[0] + 1,
981                              ino, bytenr, orig_offset,
982                              &other_start, &other_end)) {
983                 if (recow) {
984                         btrfs_release_path(path);
985                         goto again;
986                 }
987                 extent_end = other_end;
988                 del_slot = path->slots[0] + 1;
989                 del_nr++;
990                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
991                                         0, root->root_key.objectid,
992                                         ino, orig_offset, 0);
993                 BUG_ON(ret);
994         }
995         other_start = 0;
996         other_end = start;
997         if (extent_mergeable(leaf, path->slots[0] - 1,
998                              ino, bytenr, orig_offset,
999                              &other_start, &other_end)) {
1000                 if (recow) {
1001                         btrfs_release_path(path);
1002                         goto again;
1003                 }
1004                 key.offset = other_start;
1005                 del_slot = path->slots[0];
1006                 del_nr++;
1007                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
1008                                         0, root->root_key.objectid,
1009                                         ino, orig_offset, 0);
1010                 BUG_ON(ret);
1011         }
1012         if (del_nr == 0) {
1013                 fi = btrfs_item_ptr(leaf, path->slots[0],
1014                            struct btrfs_file_extent_item);
1015                 btrfs_set_file_extent_type(leaf, fi,
1016                                            BTRFS_FILE_EXTENT_REG);
1017                 btrfs_mark_buffer_dirty(leaf);
1018         } else {
1019                 fi = btrfs_item_ptr(leaf, del_slot - 1,
1020                            struct btrfs_file_extent_item);
1021                 btrfs_set_file_extent_type(leaf, fi,
1022                                            BTRFS_FILE_EXTENT_REG);
1023                 btrfs_set_file_extent_num_bytes(leaf, fi,
1024                                                 extent_end - key.offset);
1025                 btrfs_mark_buffer_dirty(leaf);
1026
1027                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
1028                 BUG_ON(ret);
1029         }
1030 out:
1031         btrfs_free_path(path);
1032         return 0;
1033 }
1034
1035 /*
1036  * on error we return an unlocked page and the error value
1037  * on success we return a locked page and 0
1038  */
1039 static int prepare_uptodate_page(struct page *page, u64 pos,
1040                                  bool force_uptodate)
1041 {
1042         int ret = 0;
1043
1044         if (((pos & (PAGE_CACHE_SIZE - 1)) || force_uptodate) &&
1045             !PageUptodate(page)) {
1046                 ret = btrfs_readpage(NULL, page);
1047                 if (ret)
1048                         return ret;
1049                 lock_page(page);
1050                 if (!PageUptodate(page)) {
1051                         unlock_page(page);
1052                         return -EIO;
1053                 }
1054         }
1055         return 0;
1056 }
1057
1058 /*
1059  * this gets pages into the page cache and locks them down, it also properly
1060  * waits for data=ordered extents to finish before allowing the pages to be
1061  * modified.
1062  */
1063 static noinline int prepare_pages(struct btrfs_root *root, struct file *file,
1064                          struct page **pages, size_t num_pages,
1065                          loff_t pos, unsigned long first_index,
1066                          size_t write_bytes, bool force_uptodate)
1067 {
1068         struct extent_state *cached_state = NULL;
1069         int i;
1070         unsigned long index = pos >> PAGE_CACHE_SHIFT;
1071         struct inode *inode = fdentry(file)->d_inode;
1072         gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
1073         int err = 0;
1074         int faili = 0;
1075         u64 start_pos;
1076         u64 last_pos;
1077
1078         start_pos = pos & ~((u64)root->sectorsize - 1);
1079         last_pos = ((u64)index + num_pages) << PAGE_CACHE_SHIFT;
1080
1081 again:
1082         for (i = 0; i < num_pages; i++) {
1083                 pages[i] = find_or_create_page(inode->i_mapping, index + i,
1084                                                mask | __GFP_WRITE);
1085                 if (!pages[i]) {
1086                         faili = i - 1;
1087                         err = -ENOMEM;
1088                         goto fail;
1089                 }
1090
1091                 if (i == 0)
1092                         err = prepare_uptodate_page(pages[i], pos,
1093                                                     force_uptodate);
1094                 if (i == num_pages - 1)
1095                         err = prepare_uptodate_page(pages[i],
1096                                                     pos + write_bytes, false);
1097                 if (err) {
1098                         page_cache_release(pages[i]);
1099                         faili = i - 1;
1100                         goto fail;
1101                 }
1102                 wait_on_page_writeback(pages[i]);
1103         }
1104         err = 0;
1105         if (start_pos < inode->i_size) {
1106                 struct btrfs_ordered_extent *ordered;
1107                 lock_extent_bits(&BTRFS_I(inode)->io_tree,
1108                                  start_pos, last_pos - 1, 0, &cached_state,
1109                                  GFP_NOFS);
1110                 ordered = btrfs_lookup_first_ordered_extent(inode,
1111                                                             last_pos - 1);
1112                 if (ordered &&
1113                     ordered->file_offset + ordered->len > start_pos &&
1114                     ordered->file_offset < last_pos) {
1115                         btrfs_put_ordered_extent(ordered);
1116                         unlock_extent_cached(&BTRFS_I(inode)->io_tree,
1117                                              start_pos, last_pos - 1,
1118                                              &cached_state, GFP_NOFS);
1119                         for (i = 0; i < num_pages; i++) {
1120                                 unlock_page(pages[i]);
1121                                 page_cache_release(pages[i]);
1122                         }
1123                         btrfs_wait_ordered_range(inode, start_pos,
1124                                                  last_pos - start_pos);
1125                         goto again;
1126                 }
1127                 if (ordered)
1128                         btrfs_put_ordered_extent(ordered);
1129
1130                 clear_extent_bit(&BTRFS_I(inode)->io_tree, start_pos,
1131                                   last_pos - 1, EXTENT_DIRTY | EXTENT_DELALLOC |
1132                                   EXTENT_DO_ACCOUNTING, 0, 0, &cached_state,
1133                                   GFP_NOFS);
1134                 unlock_extent_cached(&BTRFS_I(inode)->io_tree,
1135                                      start_pos, last_pos - 1, &cached_state,
1136                                      GFP_NOFS);
1137         }
1138         for (i = 0; i < num_pages; i++) {
1139                 if (clear_page_dirty_for_io(pages[i]))
1140                         account_page_redirty(pages[i]);
1141                 set_page_extent_mapped(pages[i]);
1142                 WARN_ON(!PageLocked(pages[i]));
1143         }
1144         return 0;
1145 fail:
1146         while (faili >= 0) {
1147                 unlock_page(pages[faili]);
1148                 page_cache_release(pages[faili]);
1149                 faili--;
1150         }
1151         return err;
1152
1153 }
1154
1155 static noinline ssize_t __btrfs_buffered_write(struct file *file,
1156                                                struct iov_iter *i,
1157                                                loff_t pos)
1158 {
1159         struct inode *inode = fdentry(file)->d_inode;
1160         struct btrfs_root *root = BTRFS_I(inode)->root;
1161         struct page **pages = NULL;
1162         unsigned long first_index;
1163         size_t num_written = 0;
1164         int nrptrs;
1165         int ret = 0;
1166         bool force_page_uptodate = false;
1167
1168         nrptrs = min((iov_iter_count(i) + PAGE_CACHE_SIZE - 1) /
1169                      PAGE_CACHE_SIZE, PAGE_CACHE_SIZE /
1170                      (sizeof(struct page *)));
1171         nrptrs = min(nrptrs, current->nr_dirtied_pause - current->nr_dirtied);
1172         nrptrs = max(nrptrs, 8);
1173         pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
1174         if (!pages)
1175                 return -ENOMEM;
1176
1177         first_index = pos >> PAGE_CACHE_SHIFT;
1178
1179         while (iov_iter_count(i) > 0) {
1180                 size_t offset = pos & (PAGE_CACHE_SIZE - 1);
1181                 size_t write_bytes = min(iov_iter_count(i),
1182                                          nrptrs * (size_t)PAGE_CACHE_SIZE -
1183                                          offset);
1184                 size_t num_pages = (write_bytes + offset +
1185                                     PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1186                 size_t dirty_pages;
1187                 size_t copied;
1188
1189                 WARN_ON(num_pages > nrptrs);
1190
1191                 /*
1192                  * Fault pages before locking them in prepare_pages
1193                  * to avoid recursive lock
1194                  */
1195                 if (unlikely(iov_iter_fault_in_readable(i, write_bytes))) {
1196                         ret = -EFAULT;
1197                         break;
1198                 }
1199
1200                 ret = btrfs_delalloc_reserve_space(inode,
1201                                         num_pages << PAGE_CACHE_SHIFT);
1202                 if (ret)
1203                         break;
1204
1205                 /*
1206                  * This is going to setup the pages array with the number of
1207                  * pages we want, so we don't really need to worry about the
1208                  * contents of pages from loop to loop
1209                  */
1210                 ret = prepare_pages(root, file, pages, num_pages,
1211                                     pos, first_index, write_bytes,
1212                                     force_page_uptodate);
1213                 if (ret) {
1214                         btrfs_delalloc_release_space(inode,
1215                                         num_pages << PAGE_CACHE_SHIFT);
1216                         break;
1217                 }
1218
1219                 copied = btrfs_copy_from_user(pos, num_pages,
1220                                            write_bytes, pages, i);
1221
1222                 /*
1223                  * if we have trouble faulting in the pages, fall
1224                  * back to one page at a time
1225                  */
1226                 if (copied < write_bytes)
1227                         nrptrs = 1;
1228
1229                 if (copied == 0) {
1230                         force_page_uptodate = true;
1231                         dirty_pages = 0;
1232                 } else {
1233                         force_page_uptodate = false;
1234                         dirty_pages = (copied + offset +
1235                                        PAGE_CACHE_SIZE - 1) >>
1236                                        PAGE_CACHE_SHIFT;
1237                 }
1238
1239                 /*
1240                  * If we had a short copy we need to release the excess delaloc
1241                  * bytes we reserved.  We need to increment outstanding_extents
1242                  * because btrfs_delalloc_release_space will decrement it, but
1243                  * we still have an outstanding extent for the chunk we actually
1244                  * managed to copy.
1245                  */
1246                 if (num_pages > dirty_pages) {
1247                         if (copied > 0) {
1248                                 spin_lock(&BTRFS_I(inode)->lock);
1249                                 BTRFS_I(inode)->outstanding_extents++;
1250                                 spin_unlock(&BTRFS_I(inode)->lock);
1251                         }
1252                         btrfs_delalloc_release_space(inode,
1253                                         (num_pages - dirty_pages) <<
1254                                         PAGE_CACHE_SHIFT);
1255                 }
1256
1257                 if (copied > 0) {
1258                         ret = btrfs_dirty_pages(root, inode, pages,
1259                                                 dirty_pages, pos, copied,
1260                                                 NULL);
1261                         if (ret) {
1262                                 btrfs_delalloc_release_space(inode,
1263                                         dirty_pages << PAGE_CACHE_SHIFT);
1264                                 btrfs_drop_pages(pages, num_pages);
1265                                 break;
1266                         }
1267                 }
1268
1269                 btrfs_drop_pages(pages, num_pages);
1270
1271                 cond_resched();
1272
1273                 balance_dirty_pages_ratelimited_nr(inode->i_mapping,
1274                                                    dirty_pages);
1275                 if (dirty_pages < (root->leafsize >> PAGE_CACHE_SHIFT) + 1)
1276                         btrfs_btree_balance_dirty(root, 1);
1277
1278                 pos += copied;
1279                 num_written += copied;
1280         }
1281
1282         kfree(pages);
1283
1284         return num_written ? num_written : ret;
1285 }
1286
1287 static ssize_t __btrfs_direct_write(struct kiocb *iocb,
1288                                     const struct iovec *iov,
1289                                     unsigned long nr_segs, loff_t pos,
1290                                     loff_t *ppos, size_t count, size_t ocount)
1291 {
1292         struct file *file = iocb->ki_filp;
1293         struct inode *inode = fdentry(file)->d_inode;
1294         struct iov_iter i;
1295         ssize_t written;
1296         ssize_t written_buffered;
1297         loff_t endbyte;
1298         int err;
1299
1300         written = generic_file_direct_write(iocb, iov, &nr_segs, pos, ppos,
1301                                             count, ocount);
1302
1303         /*
1304          * the generic O_DIRECT will update in-memory i_size after the
1305          * DIOs are done.  But our endio handlers that update the on
1306          * disk i_size never update past the in memory i_size.  So we
1307          * need one more update here to catch any additions to the
1308          * file
1309          */
1310         if (inode->i_size != BTRFS_I(inode)->disk_i_size) {
1311                 btrfs_ordered_update_i_size(inode, inode->i_size, NULL);
1312                 mark_inode_dirty(inode);
1313         }
1314
1315         if (written < 0 || written == count)
1316                 return written;
1317
1318         pos += written;
1319         count -= written;
1320         iov_iter_init(&i, iov, nr_segs, count, written);
1321         written_buffered = __btrfs_buffered_write(file, &i, pos);
1322         if (written_buffered < 0) {
1323                 err = written_buffered;
1324                 goto out;
1325         }
1326         endbyte = pos + written_buffered - 1;
1327         err = filemap_write_and_wait_range(file->f_mapping, pos, endbyte);
1328         if (err)
1329                 goto out;
1330         written += written_buffered;
1331         *ppos = pos + written_buffered;
1332         invalidate_mapping_pages(file->f_mapping, pos >> PAGE_CACHE_SHIFT,
1333                                  endbyte >> PAGE_CACHE_SHIFT);
1334 out:
1335         return written ? written : err;
1336 }
1337
1338 static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
1339                                     const struct iovec *iov,
1340                                     unsigned long nr_segs, loff_t pos)
1341 {
1342         struct file *file = iocb->ki_filp;
1343         struct inode *inode = fdentry(file)->d_inode;
1344         struct btrfs_root *root = BTRFS_I(inode)->root;
1345         loff_t *ppos = &iocb->ki_pos;
1346         u64 start_pos;
1347         ssize_t num_written = 0;
1348         ssize_t err = 0;
1349         size_t count, ocount;
1350
1351         vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
1352
1353         mutex_lock(&inode->i_mutex);
1354
1355         err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ);
1356         if (err) {
1357                 mutex_unlock(&inode->i_mutex);
1358                 goto out;
1359         }
1360         count = ocount;
1361
1362         current->backing_dev_info = inode->i_mapping->backing_dev_info;
1363         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
1364         if (err) {
1365                 mutex_unlock(&inode->i_mutex);
1366                 goto out;
1367         }
1368
1369         if (count == 0) {
1370                 mutex_unlock(&inode->i_mutex);
1371                 goto out;
1372         }
1373
1374         err = file_remove_suid(file);
1375         if (err) {
1376                 mutex_unlock(&inode->i_mutex);
1377                 goto out;
1378         }
1379
1380         /*
1381          * If BTRFS flips readonly due to some impossible error
1382          * (fs_info->fs_state now has BTRFS_SUPER_FLAG_ERROR),
1383          * although we have opened a file as writable, we have
1384          * to stop this write operation to ensure FS consistency.
1385          */
1386         if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
1387                 mutex_unlock(&inode->i_mutex);
1388                 err = -EROFS;
1389                 goto out;
1390         }
1391
1392         err = btrfs_update_time(file);
1393         if (err) {
1394                 mutex_unlock(&inode->i_mutex);
1395                 goto out;
1396         }
1397         BTRFS_I(inode)->sequence++;
1398
1399         start_pos = round_down(pos, root->sectorsize);
1400         if (start_pos > i_size_read(inode)) {
1401                 err = btrfs_cont_expand(inode, i_size_read(inode), start_pos);
1402                 if (err) {
1403                         mutex_unlock(&inode->i_mutex);
1404                         goto out;
1405                 }
1406         }
1407
1408         if (unlikely(file->f_flags & O_DIRECT)) {
1409                 num_written = __btrfs_direct_write(iocb, iov, nr_segs,
1410                                                    pos, ppos, count, ocount);
1411         } else {
1412                 struct iov_iter i;
1413
1414                 iov_iter_init(&i, iov, nr_segs, count, num_written);
1415
1416                 num_written = __btrfs_buffered_write(file, &i, pos);
1417                 if (num_written > 0)
1418                         *ppos = pos + num_written;
1419         }
1420
1421         mutex_unlock(&inode->i_mutex);
1422
1423         /*
1424          * we want to make sure fsync finds this change
1425          * but we haven't joined a transaction running right now.
1426          *
1427          * Later on, someone is sure to update the inode and get the
1428          * real transid recorded.
1429          *
1430          * We set last_trans now to the fs_info generation + 1,
1431          * this will either be one more than the running transaction
1432          * or the generation used for the next transaction if there isn't
1433          * one running right now.
1434          */
1435         BTRFS_I(inode)->last_trans = root->fs_info->generation + 1;
1436         if (num_written > 0 || num_written == -EIOCBQUEUED) {
1437                 err = generic_write_sync(file, pos, num_written);
1438                 if (err < 0 && num_written > 0)
1439                         num_written = err;
1440         }
1441 out:
1442         current->backing_dev_info = NULL;
1443         return num_written ? num_written : err;
1444 }
1445
1446 int btrfs_release_file(struct inode *inode, struct file *filp)
1447 {
1448         /*
1449          * ordered_data_close is set by settattr when we are about to truncate
1450          * a file from a non-zero size to a zero size.  This tries to
1451          * flush down new bytes that may have been written if the
1452          * application were using truncate to replace a file in place.
1453          */
1454         if (BTRFS_I(inode)->ordered_data_close) {
1455                 BTRFS_I(inode)->ordered_data_close = 0;
1456                 btrfs_add_ordered_operation(NULL, BTRFS_I(inode)->root, inode);
1457                 if (inode->i_size > BTRFS_ORDERED_OPERATIONS_FLUSH_LIMIT)
1458                         filemap_flush(inode->i_mapping);
1459         }
1460         if (filp->private_data)
1461                 btrfs_ioctl_trans_end(filp);
1462         return 0;
1463 }
1464
1465 /*
1466  * fsync call for both files and directories.  This logs the inode into
1467  * the tree log instead of forcing full commits whenever possible.
1468  *
1469  * It needs to call filemap_fdatawait so that all ordered extent updates are
1470  * in the metadata btree are up to date for copying to the log.
1471  *
1472  * It drops the inode mutex before doing the tree log commit.  This is an
1473  * important optimization for directories because holding the mutex prevents
1474  * new operations on the dir while we write to disk.
1475  */
1476 int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
1477 {
1478         struct dentry *dentry = file->f_path.dentry;
1479         struct inode *inode = dentry->d_inode;
1480         struct btrfs_root *root = BTRFS_I(inode)->root;
1481         int ret = 0;
1482         struct btrfs_trans_handle *trans;
1483
1484         trace_btrfs_sync_file(file, datasync);
1485
1486         ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
1487         if (ret)
1488                 return ret;
1489         mutex_lock(&inode->i_mutex);
1490
1491         /* we wait first, since the writeback may change the inode */
1492         root->log_batch++;
1493         btrfs_wait_ordered_range(inode, 0, (u64)-1);
1494         root->log_batch++;
1495
1496         /*
1497          * check the transaction that last modified this inode
1498          * and see if its already been committed
1499          */
1500         if (!BTRFS_I(inode)->last_trans) {
1501                 mutex_unlock(&inode->i_mutex);
1502                 goto out;
1503         }
1504
1505         /*
1506          * if the last transaction that changed this file was before
1507          * the current transaction, we can bail out now without any
1508          * syncing
1509          */
1510         smp_mb();
1511         if (BTRFS_I(inode)->last_trans <=
1512             root->fs_info->last_trans_committed) {
1513                 BTRFS_I(inode)->last_trans = 0;
1514                 mutex_unlock(&inode->i_mutex);
1515                 goto out;
1516         }
1517
1518         /*
1519          * ok we haven't committed the transaction yet, lets do a commit
1520          */
1521         if (file->private_data)
1522                 btrfs_ioctl_trans_end(file);
1523
1524         trans = btrfs_start_transaction(root, 0);
1525         if (IS_ERR(trans)) {
1526                 ret = PTR_ERR(trans);
1527                 mutex_unlock(&inode->i_mutex);
1528                 goto out;
1529         }
1530
1531         ret = btrfs_log_dentry_safe(trans, root, dentry);
1532         if (ret < 0) {
1533                 mutex_unlock(&inode->i_mutex);
1534                 goto out;
1535         }
1536
1537         /* we've logged all the items and now have a consistent
1538          * version of the file in the log.  It is possible that
1539          * someone will come in and modify the file, but that's
1540          * fine because the log is consistent on disk, and we
1541          * have references to all of the file's extents
1542          *
1543          * It is possible that someone will come in and log the
1544          * file again, but that will end up using the synchronization
1545          * inside btrfs_sync_log to keep things safe.
1546          */
1547         mutex_unlock(&inode->i_mutex);
1548
1549         if (ret != BTRFS_NO_LOG_SYNC) {
1550                 if (ret > 0) {
1551                         ret = btrfs_commit_transaction(trans, root);
1552                 } else {
1553                         ret = btrfs_sync_log(trans, root);
1554                         if (ret == 0)
1555                                 ret = btrfs_end_transaction(trans, root);
1556                         else
1557                                 ret = btrfs_commit_transaction(trans, root);
1558                 }
1559         } else {
1560                 ret = btrfs_end_transaction(trans, root);
1561         }
1562 out:
1563         return ret > 0 ? -EIO : ret;
1564 }
1565
1566 static const struct vm_operations_struct btrfs_file_vm_ops = {
1567         .fault          = filemap_fault,
1568         .page_mkwrite   = btrfs_page_mkwrite,
1569 };
1570
1571 static int btrfs_file_mmap(struct file  *filp, struct vm_area_struct *vma)
1572 {
1573         struct address_space *mapping = filp->f_mapping;
1574
1575         if (!mapping->a_ops->readpage)
1576                 return -ENOEXEC;
1577
1578         file_accessed(filp);
1579         vma->vm_ops = &btrfs_file_vm_ops;
1580         vma->vm_flags |= VM_CAN_NONLINEAR;
1581
1582         return 0;
1583 }
1584
1585 static long btrfs_fallocate(struct file *file, int mode,
1586                             loff_t offset, loff_t len)
1587 {
1588         struct inode *inode = file->f_path.dentry->d_inode;
1589         struct extent_state *cached_state = NULL;
1590         u64 cur_offset;
1591         u64 last_byte;
1592         u64 alloc_start;
1593         u64 alloc_end;
1594         u64 alloc_hint = 0;
1595         u64 locked_end;
1596         u64 mask = BTRFS_I(inode)->root->sectorsize - 1;
1597         struct extent_map *em;
1598         int ret;
1599
1600         alloc_start = offset & ~mask;
1601         alloc_end =  (offset + len + mask) & ~mask;
1602
1603         /* We only support the FALLOC_FL_KEEP_SIZE mode */
1604         if (mode & ~FALLOC_FL_KEEP_SIZE)
1605                 return -EOPNOTSUPP;
1606
1607         /*
1608          * wait for ordered IO before we have any locks.  We'll loop again
1609          * below with the locks held.
1610          */
1611         btrfs_wait_ordered_range(inode, alloc_start, alloc_end - alloc_start);
1612
1613         mutex_lock(&inode->i_mutex);
1614         ret = inode_newsize_ok(inode, alloc_end);
1615         if (ret)
1616                 goto out;
1617
1618         if (alloc_start > inode->i_size) {
1619                 ret = btrfs_cont_expand(inode, i_size_read(inode),
1620                                         alloc_start);
1621                 if (ret)
1622                         goto out;
1623         }
1624
1625         locked_end = alloc_end - 1;
1626         while (1) {
1627                 struct btrfs_ordered_extent *ordered;
1628
1629                 /* the extent lock is ordered inside the running
1630                  * transaction
1631                  */
1632                 lock_extent_bits(&BTRFS_I(inode)->io_tree, alloc_start,
1633                                  locked_end, 0, &cached_state, GFP_NOFS);
1634                 ordered = btrfs_lookup_first_ordered_extent(inode,
1635                                                             alloc_end - 1);
1636                 if (ordered &&
1637                     ordered->file_offset + ordered->len > alloc_start &&
1638                     ordered->file_offset < alloc_end) {
1639                         btrfs_put_ordered_extent(ordered);
1640                         unlock_extent_cached(&BTRFS_I(inode)->io_tree,
1641                                              alloc_start, locked_end,
1642                                              &cached_state, GFP_NOFS);
1643                         /*
1644                          * we can't wait on the range with the transaction
1645                          * running or with the extent lock held
1646                          */
1647                         btrfs_wait_ordered_range(inode, alloc_start,
1648                                                  alloc_end - alloc_start);
1649                 } else {
1650                         if (ordered)
1651                                 btrfs_put_ordered_extent(ordered);
1652                         break;
1653                 }
1654         }
1655
1656         cur_offset = alloc_start;
1657         while (1) {
1658                 u64 actual_end;
1659
1660                 em = btrfs_get_extent(inode, NULL, 0, cur_offset,
1661                                       alloc_end - cur_offset, 0);
1662                 BUG_ON(IS_ERR_OR_NULL(em));
1663                 last_byte = min(extent_map_end(em), alloc_end);
1664                 actual_end = min_t(u64, extent_map_end(em), offset + len);
1665                 last_byte = (last_byte + mask) & ~mask;
1666
1667                 if (em->block_start == EXTENT_MAP_HOLE ||
1668                     (cur_offset >= inode->i_size &&
1669                      !test_bit(EXTENT_FLAG_PREALLOC, &em->flags))) {
1670
1671                         /*
1672                          * Make sure we have enough space before we do the
1673                          * allocation.
1674                          */
1675                         ret = btrfs_check_data_free_space(inode, last_byte -
1676                                                           cur_offset);
1677                         if (ret) {
1678                                 free_extent_map(em);
1679                                 break;
1680                         }
1681
1682                         ret = btrfs_prealloc_file_range(inode, mode, cur_offset,
1683                                                         last_byte - cur_offset,
1684                                                         1 << inode->i_blkbits,
1685                                                         offset + len,
1686                                                         &alloc_hint);
1687
1688                         /* Let go of our reservation. */
1689                         btrfs_free_reserved_data_space(inode, last_byte -
1690                                                        cur_offset);
1691                         if (ret < 0) {
1692                                 free_extent_map(em);
1693                                 break;
1694                         }
1695                 } else if (actual_end > inode->i_size &&
1696                            !(mode & FALLOC_FL_KEEP_SIZE)) {
1697                         /*
1698                          * We didn't need to allocate any more space, but we
1699                          * still extended the size of the file so we need to
1700                          * update i_size.
1701                          */
1702                         inode->i_ctime = CURRENT_TIME;
1703                         i_size_write(inode, actual_end);
1704                         btrfs_ordered_update_i_size(inode, actual_end, NULL);
1705                 }
1706                 free_extent_map(em);
1707
1708                 cur_offset = last_byte;
1709                 if (cur_offset >= alloc_end) {
1710                         ret = 0;
1711                         break;
1712                 }
1713         }
1714         unlock_extent_cached(&BTRFS_I(inode)->io_tree, alloc_start, locked_end,
1715                              &cached_state, GFP_NOFS);
1716 out:
1717         mutex_unlock(&inode->i_mutex);
1718         return ret;
1719 }
1720
1721 static int find_desired_extent(struct inode *inode, loff_t *offset, int origin)
1722 {
1723         struct btrfs_root *root = BTRFS_I(inode)->root;
1724         struct extent_map *em;
1725         struct extent_state *cached_state = NULL;
1726         u64 lockstart = *offset;
1727         u64 lockend = i_size_read(inode);
1728         u64 start = *offset;
1729         u64 orig_start = *offset;
1730         u64 len = i_size_read(inode);
1731         u64 last_end = 0;
1732         int ret = 0;
1733
1734         lockend = max_t(u64, root->sectorsize, lockend);
1735         if (lockend <= lockstart)
1736                 lockend = lockstart + root->sectorsize;
1737
1738         len = lockend - lockstart + 1;
1739
1740         len = max_t(u64, len, root->sectorsize);
1741         if (inode->i_size == 0)
1742                 return -ENXIO;
1743
1744         lock_extent_bits(&BTRFS_I(inode)->io_tree, lockstart, lockend, 0,
1745                          &cached_state, GFP_NOFS);
1746
1747         /*
1748          * Delalloc is such a pain.  If we have a hole and we have pending
1749          * delalloc for a portion of the hole we will get back a hole that
1750          * exists for the entire range since it hasn't been actually written
1751          * yet.  So to take care of this case we need to look for an extent just
1752          * before the position we want in case there is outstanding delalloc
1753          * going on here.
1754          */
1755         if (origin == SEEK_HOLE && start != 0) {
1756                 if (start <= root->sectorsize)
1757                         em = btrfs_get_extent_fiemap(inode, NULL, 0, 0,
1758                                                      root->sectorsize, 0);
1759                 else
1760                         em = btrfs_get_extent_fiemap(inode, NULL, 0,
1761                                                      start - root->sectorsize,
1762                                                      root->sectorsize, 0);
1763                 if (IS_ERR(em)) {
1764                         ret = -ENXIO;
1765                         goto out;
1766                 }
1767                 last_end = em->start + em->len;
1768                 if (em->block_start == EXTENT_MAP_DELALLOC)
1769                         last_end = min_t(u64, last_end, inode->i_size);
1770                 free_extent_map(em);
1771         }
1772
1773         while (1) {
1774                 em = btrfs_get_extent_fiemap(inode, NULL, 0, start, len, 0);
1775                 if (IS_ERR(em)) {
1776                         ret = -ENXIO;
1777                         break;
1778                 }
1779
1780                 if (em->block_start == EXTENT_MAP_HOLE) {
1781                         if (test_bit(EXTENT_FLAG_VACANCY, &em->flags)) {
1782                                 if (last_end <= orig_start) {
1783                                         free_extent_map(em);
1784                                         ret = -ENXIO;
1785                                         break;
1786                                 }
1787                         }
1788
1789                         if (origin == SEEK_HOLE) {
1790                                 *offset = start;
1791                                 free_extent_map(em);
1792                                 break;
1793                         }
1794                 } else {
1795                         if (origin == SEEK_DATA) {
1796                                 if (em->block_start == EXTENT_MAP_DELALLOC) {
1797                                         if (start >= inode->i_size) {
1798                                                 free_extent_map(em);
1799                                                 ret = -ENXIO;
1800                                                 break;
1801                                         }
1802                                 }
1803
1804                                 *offset = start;
1805                                 free_extent_map(em);
1806                                 break;
1807                         }
1808                 }
1809
1810                 start = em->start + em->len;
1811                 last_end = em->start + em->len;
1812
1813                 if (em->block_start == EXTENT_MAP_DELALLOC)
1814                         last_end = min_t(u64, last_end, inode->i_size);
1815
1816                 if (test_bit(EXTENT_FLAG_VACANCY, &em->flags)) {
1817                         free_extent_map(em);
1818                         ret = -ENXIO;
1819                         break;
1820                 }
1821                 free_extent_map(em);
1822                 cond_resched();
1823         }
1824         if (!ret)
1825                 *offset = min(*offset, inode->i_size);
1826 out:
1827         unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart, lockend,
1828                              &cached_state, GFP_NOFS);
1829         return ret;
1830 }
1831
1832 static loff_t btrfs_file_llseek(struct file *file, loff_t offset, int origin)
1833 {
1834         struct inode *inode = file->f_mapping->host;
1835         int ret;
1836
1837         mutex_lock(&inode->i_mutex);
1838         switch (origin) {
1839         case SEEK_END:
1840         case SEEK_CUR:
1841                 offset = generic_file_llseek(file, offset, origin);
1842                 goto out;
1843         case SEEK_DATA:
1844         case SEEK_HOLE:
1845                 if (offset >= i_size_read(inode)) {
1846                         mutex_unlock(&inode->i_mutex);
1847                         return -ENXIO;
1848                 }
1849
1850                 ret = find_desired_extent(inode, &offset, origin);
1851                 if (ret) {
1852                         mutex_unlock(&inode->i_mutex);
1853                         return ret;
1854                 }
1855         }
1856
1857         if (offset < 0 && !(file->f_mode & FMODE_UNSIGNED_OFFSET)) {
1858                 offset = -EINVAL;
1859                 goto out;
1860         }
1861         if (offset > inode->i_sb->s_maxbytes) {
1862                 offset = -EINVAL;
1863                 goto out;
1864         }
1865
1866         /* Special lock needed here? */
1867         if (offset != file->f_pos) {
1868                 file->f_pos = offset;
1869                 file->f_version = 0;
1870         }
1871 out:
1872         mutex_unlock(&inode->i_mutex);
1873         return offset;
1874 }
1875
1876 const struct file_operations btrfs_file_operations = {
1877         .llseek         = btrfs_file_llseek,
1878         .read           = do_sync_read,
1879         .write          = do_sync_write,
1880         .aio_read       = generic_file_aio_read,
1881         .splice_read    = generic_file_splice_read,
1882         .aio_write      = btrfs_file_aio_write,
1883         .mmap           = btrfs_file_mmap,
1884         .open           = generic_file_open,
1885         .release        = btrfs_release_file,
1886         .fsync          = btrfs_sync_file,
1887         .fallocate      = btrfs_fallocate,
1888         .unlocked_ioctl = btrfs_ioctl,
1889 #ifdef CONFIG_COMPAT
1890         .compat_ioctl   = btrfs_ioctl,
1891 #endif
1892 };