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Btrfs: fix race between snapshot deletion and getting inode
[~shefty/rdma-dev.git] / fs / btrfs / scrub.c
1 /*
2  * Copyright (C) 2011, 2012 STRATO.  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/blkdev.h>
20 #include <linux/ratelimit.h>
21 #include "ctree.h"
22 #include "volumes.h"
23 #include "disk-io.h"
24 #include "ordered-data.h"
25 #include "transaction.h"
26 #include "backref.h"
27 #include "extent_io.h"
28 #include "dev-replace.h"
29 #include "check-integrity.h"
30 #include "rcu-string.h"
31
32 /*
33  * This is only the first step towards a full-features scrub. It reads all
34  * extent and super block and verifies the checksums. In case a bad checksum
35  * is found or the extent cannot be read, good data will be written back if
36  * any can be found.
37  *
38  * Future enhancements:
39  *  - In case an unrepairable extent is encountered, track which files are
40  *    affected and report them
41  *  - track and record media errors, throw out bad devices
42  *  - add a mode to also read unallocated space
43  */
44
45 struct scrub_block;
46 struct scrub_ctx;
47
48 /*
49  * the following three values only influence the performance.
50  * The last one configures the number of parallel and outstanding I/O
51  * operations. The first two values configure an upper limit for the number
52  * of (dynamically allocated) pages that are added to a bio.
53  */
54 #define SCRUB_PAGES_PER_RD_BIO  32      /* 128k per bio */
55 #define SCRUB_PAGES_PER_WR_BIO  32      /* 128k per bio */
56 #define SCRUB_BIOS_PER_SCTX     64      /* 8MB per device in flight */
57
58 /*
59  * the following value times PAGE_SIZE needs to be large enough to match the
60  * largest node/leaf/sector size that shall be supported.
61  * Values larger than BTRFS_STRIPE_LEN are not supported.
62  */
63 #define SCRUB_MAX_PAGES_PER_BLOCK       16      /* 64k per node/leaf/sector */
64
65 struct scrub_page {
66         struct scrub_block      *sblock;
67         struct page             *page;
68         struct btrfs_device     *dev;
69         u64                     flags;  /* extent flags */
70         u64                     generation;
71         u64                     logical;
72         u64                     physical;
73         u64                     physical_for_dev_replace;
74         atomic_t                ref_count;
75         struct {
76                 unsigned int    mirror_num:8;
77                 unsigned int    have_csum:1;
78                 unsigned int    io_error:1;
79         };
80         u8                      csum[BTRFS_CSUM_SIZE];
81 };
82
83 struct scrub_bio {
84         int                     index;
85         struct scrub_ctx        *sctx;
86         struct btrfs_device     *dev;
87         struct bio              *bio;
88         int                     err;
89         u64                     logical;
90         u64                     physical;
91 #if SCRUB_PAGES_PER_WR_BIO >= SCRUB_PAGES_PER_RD_BIO
92         struct scrub_page       *pagev[SCRUB_PAGES_PER_WR_BIO];
93 #else
94         struct scrub_page       *pagev[SCRUB_PAGES_PER_RD_BIO];
95 #endif
96         int                     page_count;
97         int                     next_free;
98         struct btrfs_work       work;
99 };
100
101 struct scrub_block {
102         struct scrub_page       *pagev[SCRUB_MAX_PAGES_PER_BLOCK];
103         int                     page_count;
104         atomic_t                outstanding_pages;
105         atomic_t                ref_count; /* free mem on transition to zero */
106         struct scrub_ctx        *sctx;
107         struct {
108                 unsigned int    header_error:1;
109                 unsigned int    checksum_error:1;
110                 unsigned int    no_io_error_seen:1;
111                 unsigned int    generation_error:1; /* also sets header_error */
112         };
113 };
114
115 struct scrub_wr_ctx {
116         struct scrub_bio *wr_curr_bio;
117         struct btrfs_device *tgtdev;
118         int pages_per_wr_bio; /* <= SCRUB_PAGES_PER_WR_BIO */
119         atomic_t flush_all_writes;
120         struct mutex wr_lock;
121 };
122
123 struct scrub_ctx {
124         struct scrub_bio        *bios[SCRUB_BIOS_PER_SCTX];
125         struct btrfs_root       *dev_root;
126         int                     first_free;
127         int                     curr;
128         atomic_t                bios_in_flight;
129         atomic_t                workers_pending;
130         spinlock_t              list_lock;
131         wait_queue_head_t       list_wait;
132         u16                     csum_size;
133         struct list_head        csum_list;
134         atomic_t                cancel_req;
135         int                     readonly;
136         int                     pages_per_rd_bio;
137         u32                     sectorsize;
138         u32                     nodesize;
139         u32                     leafsize;
140
141         int                     is_dev_replace;
142         struct scrub_wr_ctx     wr_ctx;
143
144         /*
145          * statistics
146          */
147         struct btrfs_scrub_progress stat;
148         spinlock_t              stat_lock;
149 };
150
151 struct scrub_fixup_nodatasum {
152         struct scrub_ctx        *sctx;
153         struct btrfs_device     *dev;
154         u64                     logical;
155         struct btrfs_root       *root;
156         struct btrfs_work       work;
157         int                     mirror_num;
158 };
159
160 struct scrub_copy_nocow_ctx {
161         struct scrub_ctx        *sctx;
162         u64                     logical;
163         u64                     len;
164         int                     mirror_num;
165         u64                     physical_for_dev_replace;
166         struct btrfs_work       work;
167 };
168
169 struct scrub_warning {
170         struct btrfs_path       *path;
171         u64                     extent_item_size;
172         char                    *scratch_buf;
173         char                    *msg_buf;
174         const char              *errstr;
175         sector_t                sector;
176         u64                     logical;
177         struct btrfs_device     *dev;
178         int                     msg_bufsize;
179         int                     scratch_bufsize;
180 };
181
182
183 static void scrub_pending_bio_inc(struct scrub_ctx *sctx);
184 static void scrub_pending_bio_dec(struct scrub_ctx *sctx);
185 static void scrub_pending_trans_workers_inc(struct scrub_ctx *sctx);
186 static void scrub_pending_trans_workers_dec(struct scrub_ctx *sctx);
187 static int scrub_handle_errored_block(struct scrub_block *sblock_to_check);
188 static int scrub_setup_recheck_block(struct scrub_ctx *sctx,
189                                      struct btrfs_fs_info *fs_info,
190                                      struct scrub_block *original_sblock,
191                                      u64 length, u64 logical,
192                                      struct scrub_block *sblocks_for_recheck);
193 static void scrub_recheck_block(struct btrfs_fs_info *fs_info,
194                                 struct scrub_block *sblock, int is_metadata,
195                                 int have_csum, u8 *csum, u64 generation,
196                                 u16 csum_size);
197 static void scrub_recheck_block_checksum(struct btrfs_fs_info *fs_info,
198                                          struct scrub_block *sblock,
199                                          int is_metadata, int have_csum,
200                                          const u8 *csum, u64 generation,
201                                          u16 csum_size);
202 static void scrub_complete_bio_end_io(struct bio *bio, int err);
203 static int scrub_repair_block_from_good_copy(struct scrub_block *sblock_bad,
204                                              struct scrub_block *sblock_good,
205                                              int force_write);
206 static int scrub_repair_page_from_good_copy(struct scrub_block *sblock_bad,
207                                             struct scrub_block *sblock_good,
208                                             int page_num, int force_write);
209 static void scrub_write_block_to_dev_replace(struct scrub_block *sblock);
210 static int scrub_write_page_to_dev_replace(struct scrub_block *sblock,
211                                            int page_num);
212 static int scrub_checksum_data(struct scrub_block *sblock);
213 static int scrub_checksum_tree_block(struct scrub_block *sblock);
214 static int scrub_checksum_super(struct scrub_block *sblock);
215 static void scrub_block_get(struct scrub_block *sblock);
216 static void scrub_block_put(struct scrub_block *sblock);
217 static void scrub_page_get(struct scrub_page *spage);
218 static void scrub_page_put(struct scrub_page *spage);
219 static int scrub_add_page_to_rd_bio(struct scrub_ctx *sctx,
220                                     struct scrub_page *spage);
221 static int scrub_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
222                        u64 physical, struct btrfs_device *dev, u64 flags,
223                        u64 gen, int mirror_num, u8 *csum, int force,
224                        u64 physical_for_dev_replace);
225 static void scrub_bio_end_io(struct bio *bio, int err);
226 static void scrub_bio_end_io_worker(struct btrfs_work *work);
227 static void scrub_block_complete(struct scrub_block *sblock);
228 static void scrub_remap_extent(struct btrfs_fs_info *fs_info,
229                                u64 extent_logical, u64 extent_len,
230                                u64 *extent_physical,
231                                struct btrfs_device **extent_dev,
232                                int *extent_mirror_num);
233 static int scrub_setup_wr_ctx(struct scrub_ctx *sctx,
234                               struct scrub_wr_ctx *wr_ctx,
235                               struct btrfs_fs_info *fs_info,
236                               struct btrfs_device *dev,
237                               int is_dev_replace);
238 static void scrub_free_wr_ctx(struct scrub_wr_ctx *wr_ctx);
239 static int scrub_add_page_to_wr_bio(struct scrub_ctx *sctx,
240                                     struct scrub_page *spage);
241 static void scrub_wr_submit(struct scrub_ctx *sctx);
242 static void scrub_wr_bio_end_io(struct bio *bio, int err);
243 static void scrub_wr_bio_end_io_worker(struct btrfs_work *work);
244 static int write_page_nocow(struct scrub_ctx *sctx,
245                             u64 physical_for_dev_replace, struct page *page);
246 static int copy_nocow_pages_for_inode(u64 inum, u64 offset, u64 root,
247                                       void *ctx);
248 static int copy_nocow_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
249                             int mirror_num, u64 physical_for_dev_replace);
250 static void copy_nocow_pages_worker(struct btrfs_work *work);
251
252
253 static void scrub_pending_bio_inc(struct scrub_ctx *sctx)
254 {
255         atomic_inc(&sctx->bios_in_flight);
256 }
257
258 static void scrub_pending_bio_dec(struct scrub_ctx *sctx)
259 {
260         atomic_dec(&sctx->bios_in_flight);
261         wake_up(&sctx->list_wait);
262 }
263
264 /*
265  * used for workers that require transaction commits (i.e., for the
266  * NOCOW case)
267  */
268 static void scrub_pending_trans_workers_inc(struct scrub_ctx *sctx)
269 {
270         struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
271
272         /*
273          * increment scrubs_running to prevent cancel requests from
274          * completing as long as a worker is running. we must also
275          * increment scrubs_paused to prevent deadlocking on pause
276          * requests used for transactions commits (as the worker uses a
277          * transaction context). it is safe to regard the worker
278          * as paused for all matters practical. effectively, we only
279          * avoid cancellation requests from completing.
280          */
281         mutex_lock(&fs_info->scrub_lock);
282         atomic_inc(&fs_info->scrubs_running);
283         atomic_inc(&fs_info->scrubs_paused);
284         mutex_unlock(&fs_info->scrub_lock);
285         atomic_inc(&sctx->workers_pending);
286 }
287
288 /* used for workers that require transaction commits */
289 static void scrub_pending_trans_workers_dec(struct scrub_ctx *sctx)
290 {
291         struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
292
293         /*
294          * see scrub_pending_trans_workers_inc() why we're pretending
295          * to be paused in the scrub counters
296          */
297         mutex_lock(&fs_info->scrub_lock);
298         atomic_dec(&fs_info->scrubs_running);
299         atomic_dec(&fs_info->scrubs_paused);
300         mutex_unlock(&fs_info->scrub_lock);
301         atomic_dec(&sctx->workers_pending);
302         wake_up(&fs_info->scrub_pause_wait);
303         wake_up(&sctx->list_wait);
304 }
305
306 static void scrub_free_csums(struct scrub_ctx *sctx)
307 {
308         while (!list_empty(&sctx->csum_list)) {
309                 struct btrfs_ordered_sum *sum;
310                 sum = list_first_entry(&sctx->csum_list,
311                                        struct btrfs_ordered_sum, list);
312                 list_del(&sum->list);
313                 kfree(sum);
314         }
315 }
316
317 static noinline_for_stack void scrub_free_ctx(struct scrub_ctx *sctx)
318 {
319         int i;
320
321         if (!sctx)
322                 return;
323
324         scrub_free_wr_ctx(&sctx->wr_ctx);
325
326         /* this can happen when scrub is cancelled */
327         if (sctx->curr != -1) {
328                 struct scrub_bio *sbio = sctx->bios[sctx->curr];
329
330                 for (i = 0; i < sbio->page_count; i++) {
331                         WARN_ON(!sbio->pagev[i]->page);
332                         scrub_block_put(sbio->pagev[i]->sblock);
333                 }
334                 bio_put(sbio->bio);
335         }
336
337         for (i = 0; i < SCRUB_BIOS_PER_SCTX; ++i) {
338                 struct scrub_bio *sbio = sctx->bios[i];
339
340                 if (!sbio)
341                         break;
342                 kfree(sbio);
343         }
344
345         scrub_free_csums(sctx);
346         kfree(sctx);
347 }
348
349 static noinline_for_stack
350 struct scrub_ctx *scrub_setup_ctx(struct btrfs_device *dev, int is_dev_replace)
351 {
352         struct scrub_ctx *sctx;
353         int             i;
354         struct btrfs_fs_info *fs_info = dev->dev_root->fs_info;
355         int pages_per_rd_bio;
356         int ret;
357
358         /*
359          * the setting of pages_per_rd_bio is correct for scrub but might
360          * be wrong for the dev_replace code where we might read from
361          * different devices in the initial huge bios. However, that
362          * code is able to correctly handle the case when adding a page
363          * to a bio fails.
364          */
365         if (dev->bdev)
366                 pages_per_rd_bio = min_t(int, SCRUB_PAGES_PER_RD_BIO,
367                                          bio_get_nr_vecs(dev->bdev));
368         else
369                 pages_per_rd_bio = SCRUB_PAGES_PER_RD_BIO;
370         sctx = kzalloc(sizeof(*sctx), GFP_NOFS);
371         if (!sctx)
372                 goto nomem;
373         sctx->is_dev_replace = is_dev_replace;
374         sctx->pages_per_rd_bio = pages_per_rd_bio;
375         sctx->curr = -1;
376         sctx->dev_root = dev->dev_root;
377         for (i = 0; i < SCRUB_BIOS_PER_SCTX; ++i) {
378                 struct scrub_bio *sbio;
379
380                 sbio = kzalloc(sizeof(*sbio), GFP_NOFS);
381                 if (!sbio)
382                         goto nomem;
383                 sctx->bios[i] = sbio;
384
385                 sbio->index = i;
386                 sbio->sctx = sctx;
387                 sbio->page_count = 0;
388                 sbio->work.func = scrub_bio_end_io_worker;
389
390                 if (i != SCRUB_BIOS_PER_SCTX - 1)
391                         sctx->bios[i]->next_free = i + 1;
392                 else
393                         sctx->bios[i]->next_free = -1;
394         }
395         sctx->first_free = 0;
396         sctx->nodesize = dev->dev_root->nodesize;
397         sctx->leafsize = dev->dev_root->leafsize;
398         sctx->sectorsize = dev->dev_root->sectorsize;
399         atomic_set(&sctx->bios_in_flight, 0);
400         atomic_set(&sctx->workers_pending, 0);
401         atomic_set(&sctx->cancel_req, 0);
402         sctx->csum_size = btrfs_super_csum_size(fs_info->super_copy);
403         INIT_LIST_HEAD(&sctx->csum_list);
404
405         spin_lock_init(&sctx->list_lock);
406         spin_lock_init(&sctx->stat_lock);
407         init_waitqueue_head(&sctx->list_wait);
408
409         ret = scrub_setup_wr_ctx(sctx, &sctx->wr_ctx, fs_info,
410                                  fs_info->dev_replace.tgtdev, is_dev_replace);
411         if (ret) {
412                 scrub_free_ctx(sctx);
413                 return ERR_PTR(ret);
414         }
415         return sctx;
416
417 nomem:
418         scrub_free_ctx(sctx);
419         return ERR_PTR(-ENOMEM);
420 }
421
422 static int scrub_print_warning_inode(u64 inum, u64 offset, u64 root,
423                                      void *warn_ctx)
424 {
425         u64 isize;
426         u32 nlink;
427         int ret;
428         int i;
429         struct extent_buffer *eb;
430         struct btrfs_inode_item *inode_item;
431         struct scrub_warning *swarn = warn_ctx;
432         struct btrfs_fs_info *fs_info = swarn->dev->dev_root->fs_info;
433         struct inode_fs_paths *ipath = NULL;
434         struct btrfs_root *local_root;
435         struct btrfs_key root_key;
436
437         root_key.objectid = root;
438         root_key.type = BTRFS_ROOT_ITEM_KEY;
439         root_key.offset = (u64)-1;
440         local_root = btrfs_read_fs_root_no_name(fs_info, &root_key);
441         if (IS_ERR(local_root)) {
442                 ret = PTR_ERR(local_root);
443                 goto err;
444         }
445
446         ret = inode_item_info(inum, 0, local_root, swarn->path);
447         if (ret) {
448                 btrfs_release_path(swarn->path);
449                 goto err;
450         }
451
452         eb = swarn->path->nodes[0];
453         inode_item = btrfs_item_ptr(eb, swarn->path->slots[0],
454                                         struct btrfs_inode_item);
455         isize = btrfs_inode_size(eb, inode_item);
456         nlink = btrfs_inode_nlink(eb, inode_item);
457         btrfs_release_path(swarn->path);
458
459         ipath = init_ipath(4096, local_root, swarn->path);
460         if (IS_ERR(ipath)) {
461                 ret = PTR_ERR(ipath);
462                 ipath = NULL;
463                 goto err;
464         }
465         ret = paths_from_inode(inum, ipath);
466
467         if (ret < 0)
468                 goto err;
469
470         /*
471          * we deliberately ignore the bit ipath might have been too small to
472          * hold all of the paths here
473          */
474         for (i = 0; i < ipath->fspath->elem_cnt; ++i)
475                 printk_in_rcu(KERN_WARNING "btrfs: %s at logical %llu on dev "
476                         "%s, sector %llu, root %llu, inode %llu, offset %llu, "
477                         "length %llu, links %u (path: %s)\n", swarn->errstr,
478                         swarn->logical, rcu_str_deref(swarn->dev->name),
479                         (unsigned long long)swarn->sector, root, inum, offset,
480                         min(isize - offset, (u64)PAGE_SIZE), nlink,
481                         (char *)(unsigned long)ipath->fspath->val[i]);
482
483         free_ipath(ipath);
484         return 0;
485
486 err:
487         printk_in_rcu(KERN_WARNING "btrfs: %s at logical %llu on dev "
488                 "%s, sector %llu, root %llu, inode %llu, offset %llu: path "
489                 "resolving failed with ret=%d\n", swarn->errstr,
490                 swarn->logical, rcu_str_deref(swarn->dev->name),
491                 (unsigned long long)swarn->sector, root, inum, offset, ret);
492
493         free_ipath(ipath);
494         return 0;
495 }
496
497 static void scrub_print_warning(const char *errstr, struct scrub_block *sblock)
498 {
499         struct btrfs_device *dev;
500         struct btrfs_fs_info *fs_info;
501         struct btrfs_path *path;
502         struct btrfs_key found_key;
503         struct extent_buffer *eb;
504         struct btrfs_extent_item *ei;
505         struct scrub_warning swarn;
506         unsigned long ptr = 0;
507         u64 extent_item_pos;
508         u64 flags = 0;
509         u64 ref_root;
510         u32 item_size;
511         u8 ref_level;
512         const int bufsize = 4096;
513         int ret;
514
515         WARN_ON(sblock->page_count < 1);
516         dev = sblock->pagev[0]->dev;
517         fs_info = sblock->sctx->dev_root->fs_info;
518
519         path = btrfs_alloc_path();
520
521         swarn.scratch_buf = kmalloc(bufsize, GFP_NOFS);
522         swarn.msg_buf = kmalloc(bufsize, GFP_NOFS);
523         swarn.sector = (sblock->pagev[0]->physical) >> 9;
524         swarn.logical = sblock->pagev[0]->logical;
525         swarn.errstr = errstr;
526         swarn.dev = NULL;
527         swarn.msg_bufsize = bufsize;
528         swarn.scratch_bufsize = bufsize;
529
530         if (!path || !swarn.scratch_buf || !swarn.msg_buf)
531                 goto out;
532
533         ret = extent_from_logical(fs_info, swarn.logical, path, &found_key,
534                                   &flags);
535         if (ret < 0)
536                 goto out;
537
538         extent_item_pos = swarn.logical - found_key.objectid;
539         swarn.extent_item_size = found_key.offset;
540
541         eb = path->nodes[0];
542         ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
543         item_size = btrfs_item_size_nr(eb, path->slots[0]);
544         btrfs_release_path(path);
545
546         if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
547                 do {
548                         ret = tree_backref_for_extent(&ptr, eb, ei, item_size,
549                                                         &ref_root, &ref_level);
550                         printk_in_rcu(KERN_WARNING
551                                 "btrfs: %s at logical %llu on dev %s, "
552                                 "sector %llu: metadata %s (level %d) in tree "
553                                 "%llu\n", errstr, swarn.logical,
554                                 rcu_str_deref(dev->name),
555                                 (unsigned long long)swarn.sector,
556                                 ref_level ? "node" : "leaf",
557                                 ret < 0 ? -1 : ref_level,
558                                 ret < 0 ? -1 : ref_root);
559                 } while (ret != 1);
560         } else {
561                 swarn.path = path;
562                 swarn.dev = dev;
563                 iterate_extent_inodes(fs_info, found_key.objectid,
564                                         extent_item_pos, 1,
565                                         scrub_print_warning_inode, &swarn);
566         }
567
568 out:
569         btrfs_free_path(path);
570         kfree(swarn.scratch_buf);
571         kfree(swarn.msg_buf);
572 }
573
574 static int scrub_fixup_readpage(u64 inum, u64 offset, u64 root, void *fixup_ctx)
575 {
576         struct page *page = NULL;
577         unsigned long index;
578         struct scrub_fixup_nodatasum *fixup = fixup_ctx;
579         int ret;
580         int corrected = 0;
581         struct btrfs_key key;
582         struct inode *inode = NULL;
583         struct btrfs_fs_info *fs_info;
584         u64 end = offset + PAGE_SIZE - 1;
585         struct btrfs_root *local_root;
586         int srcu_index;
587
588         key.objectid = root;
589         key.type = BTRFS_ROOT_ITEM_KEY;
590         key.offset = (u64)-1;
591
592         fs_info = fixup->root->fs_info;
593         srcu_index = srcu_read_lock(&fs_info->subvol_srcu);
594
595         local_root = btrfs_read_fs_root_no_name(fs_info, &key);
596         if (IS_ERR(local_root)) {
597                 srcu_read_unlock(&fs_info->subvol_srcu, srcu_index);
598                 return PTR_ERR(local_root);
599         }
600
601         key.type = BTRFS_INODE_ITEM_KEY;
602         key.objectid = inum;
603         key.offset = 0;
604         inode = btrfs_iget(fs_info->sb, &key, local_root, NULL);
605         srcu_read_unlock(&fs_info->subvol_srcu, srcu_index);
606         if (IS_ERR(inode))
607                 return PTR_ERR(inode);
608
609         index = offset >> PAGE_CACHE_SHIFT;
610
611         page = find_or_create_page(inode->i_mapping, index, GFP_NOFS);
612         if (!page) {
613                 ret = -ENOMEM;
614                 goto out;
615         }
616
617         if (PageUptodate(page)) {
618                 if (PageDirty(page)) {
619                         /*
620                          * we need to write the data to the defect sector. the
621                          * data that was in that sector is not in memory,
622                          * because the page was modified. we must not write the
623                          * modified page to that sector.
624                          *
625                          * TODO: what could be done here: wait for the delalloc
626                          *       runner to write out that page (might involve
627                          *       COW) and see whether the sector is still
628                          *       referenced afterwards.
629                          *
630                          * For the meantime, we'll treat this error
631                          * incorrectable, although there is a chance that a
632                          * later scrub will find the bad sector again and that
633                          * there's no dirty page in memory, then.
634                          */
635                         ret = -EIO;
636                         goto out;
637                 }
638                 fs_info = BTRFS_I(inode)->root->fs_info;
639                 ret = repair_io_failure(fs_info, offset, PAGE_SIZE,
640                                         fixup->logical, page,
641                                         fixup->mirror_num);
642                 unlock_page(page);
643                 corrected = !ret;
644         } else {
645                 /*
646                  * we need to get good data first. the general readpage path
647                  * will call repair_io_failure for us, we just have to make
648                  * sure we read the bad mirror.
649                  */
650                 ret = set_extent_bits(&BTRFS_I(inode)->io_tree, offset, end,
651                                         EXTENT_DAMAGED, GFP_NOFS);
652                 if (ret) {
653                         /* set_extent_bits should give proper error */
654                         WARN_ON(ret > 0);
655                         if (ret > 0)
656                                 ret = -EFAULT;
657                         goto out;
658                 }
659
660                 ret = extent_read_full_page(&BTRFS_I(inode)->io_tree, page,
661                                                 btrfs_get_extent,
662                                                 fixup->mirror_num);
663                 wait_on_page_locked(page);
664
665                 corrected = !test_range_bit(&BTRFS_I(inode)->io_tree, offset,
666                                                 end, EXTENT_DAMAGED, 0, NULL);
667                 if (!corrected)
668                         clear_extent_bits(&BTRFS_I(inode)->io_tree, offset, end,
669                                                 EXTENT_DAMAGED, GFP_NOFS);
670         }
671
672 out:
673         if (page)
674                 put_page(page);
675         if (inode)
676                 iput(inode);
677
678         if (ret < 0)
679                 return ret;
680
681         if (ret == 0 && corrected) {
682                 /*
683                  * we only need to call readpage for one of the inodes belonging
684                  * to this extent. so make iterate_extent_inodes stop
685                  */
686                 return 1;
687         }
688
689         return -EIO;
690 }
691
692 static void scrub_fixup_nodatasum(struct btrfs_work *work)
693 {
694         int ret;
695         struct scrub_fixup_nodatasum *fixup;
696         struct scrub_ctx *sctx;
697         struct btrfs_trans_handle *trans = NULL;
698         struct btrfs_fs_info *fs_info;
699         struct btrfs_path *path;
700         int uncorrectable = 0;
701
702         fixup = container_of(work, struct scrub_fixup_nodatasum, work);
703         sctx = fixup->sctx;
704         fs_info = fixup->root->fs_info;
705
706         path = btrfs_alloc_path();
707         if (!path) {
708                 spin_lock(&sctx->stat_lock);
709                 ++sctx->stat.malloc_errors;
710                 spin_unlock(&sctx->stat_lock);
711                 uncorrectable = 1;
712                 goto out;
713         }
714
715         trans = btrfs_join_transaction(fixup->root);
716         if (IS_ERR(trans)) {
717                 uncorrectable = 1;
718                 goto out;
719         }
720
721         /*
722          * the idea is to trigger a regular read through the standard path. we
723          * read a page from the (failed) logical address by specifying the
724          * corresponding copynum of the failed sector. thus, that readpage is
725          * expected to fail.
726          * that is the point where on-the-fly error correction will kick in
727          * (once it's finished) and rewrite the failed sector if a good copy
728          * can be found.
729          */
730         ret = iterate_inodes_from_logical(fixup->logical, fixup->root->fs_info,
731                                                 path, scrub_fixup_readpage,
732                                                 fixup);
733         if (ret < 0) {
734                 uncorrectable = 1;
735                 goto out;
736         }
737         WARN_ON(ret != 1);
738
739         spin_lock(&sctx->stat_lock);
740         ++sctx->stat.corrected_errors;
741         spin_unlock(&sctx->stat_lock);
742
743 out:
744         if (trans && !IS_ERR(trans))
745                 btrfs_end_transaction(trans, fixup->root);
746         if (uncorrectable) {
747                 spin_lock(&sctx->stat_lock);
748                 ++sctx->stat.uncorrectable_errors;
749                 spin_unlock(&sctx->stat_lock);
750                 btrfs_dev_replace_stats_inc(
751                         &sctx->dev_root->fs_info->dev_replace.
752                         num_uncorrectable_read_errors);
753                 printk_ratelimited_in_rcu(KERN_ERR
754                         "btrfs: unable to fixup (nodatasum) error at logical %llu on dev %s\n",
755                         (unsigned long long)fixup->logical,
756                         rcu_str_deref(fixup->dev->name));
757         }
758
759         btrfs_free_path(path);
760         kfree(fixup);
761
762         scrub_pending_trans_workers_dec(sctx);
763 }
764
765 /*
766  * scrub_handle_errored_block gets called when either verification of the
767  * pages failed or the bio failed to read, e.g. with EIO. In the latter
768  * case, this function handles all pages in the bio, even though only one
769  * may be bad.
770  * The goal of this function is to repair the errored block by using the
771  * contents of one of the mirrors.
772  */
773 static int scrub_handle_errored_block(struct scrub_block *sblock_to_check)
774 {
775         struct scrub_ctx *sctx = sblock_to_check->sctx;
776         struct btrfs_device *dev;
777         struct btrfs_fs_info *fs_info;
778         u64 length;
779         u64 logical;
780         u64 generation;
781         unsigned int failed_mirror_index;
782         unsigned int is_metadata;
783         unsigned int have_csum;
784         u8 *csum;
785         struct scrub_block *sblocks_for_recheck; /* holds one for each mirror */
786         struct scrub_block *sblock_bad;
787         int ret;
788         int mirror_index;
789         int page_num;
790         int success;
791         static DEFINE_RATELIMIT_STATE(_rs, DEFAULT_RATELIMIT_INTERVAL,
792                                       DEFAULT_RATELIMIT_BURST);
793
794         BUG_ON(sblock_to_check->page_count < 1);
795         fs_info = sctx->dev_root->fs_info;
796         if (sblock_to_check->pagev[0]->flags & BTRFS_EXTENT_FLAG_SUPER) {
797                 /*
798                  * if we find an error in a super block, we just report it.
799                  * They will get written with the next transaction commit
800                  * anyway
801                  */
802                 spin_lock(&sctx->stat_lock);
803                 ++sctx->stat.super_errors;
804                 spin_unlock(&sctx->stat_lock);
805                 return 0;
806         }
807         length = sblock_to_check->page_count * PAGE_SIZE;
808         logical = sblock_to_check->pagev[0]->logical;
809         generation = sblock_to_check->pagev[0]->generation;
810         BUG_ON(sblock_to_check->pagev[0]->mirror_num < 1);
811         failed_mirror_index = sblock_to_check->pagev[0]->mirror_num - 1;
812         is_metadata = !(sblock_to_check->pagev[0]->flags &
813                         BTRFS_EXTENT_FLAG_DATA);
814         have_csum = sblock_to_check->pagev[0]->have_csum;
815         csum = sblock_to_check->pagev[0]->csum;
816         dev = sblock_to_check->pagev[0]->dev;
817
818         if (sctx->is_dev_replace && !is_metadata && !have_csum) {
819                 sblocks_for_recheck = NULL;
820                 goto nodatasum_case;
821         }
822
823         /*
824          * read all mirrors one after the other. This includes to
825          * re-read the extent or metadata block that failed (that was
826          * the cause that this fixup code is called) another time,
827          * page by page this time in order to know which pages
828          * caused I/O errors and which ones are good (for all mirrors).
829          * It is the goal to handle the situation when more than one
830          * mirror contains I/O errors, but the errors do not
831          * overlap, i.e. the data can be repaired by selecting the
832          * pages from those mirrors without I/O error on the
833          * particular pages. One example (with blocks >= 2 * PAGE_SIZE)
834          * would be that mirror #1 has an I/O error on the first page,
835          * the second page is good, and mirror #2 has an I/O error on
836          * the second page, but the first page is good.
837          * Then the first page of the first mirror can be repaired by
838          * taking the first page of the second mirror, and the
839          * second page of the second mirror can be repaired by
840          * copying the contents of the 2nd page of the 1st mirror.
841          * One more note: if the pages of one mirror contain I/O
842          * errors, the checksum cannot be verified. In order to get
843          * the best data for repairing, the first attempt is to find
844          * a mirror without I/O errors and with a validated checksum.
845          * Only if this is not possible, the pages are picked from
846          * mirrors with I/O errors without considering the checksum.
847          * If the latter is the case, at the end, the checksum of the
848          * repaired area is verified in order to correctly maintain
849          * the statistics.
850          */
851
852         sblocks_for_recheck = kzalloc(BTRFS_MAX_MIRRORS *
853                                      sizeof(*sblocks_for_recheck),
854                                      GFP_NOFS);
855         if (!sblocks_for_recheck) {
856                 spin_lock(&sctx->stat_lock);
857                 sctx->stat.malloc_errors++;
858                 sctx->stat.read_errors++;
859                 sctx->stat.uncorrectable_errors++;
860                 spin_unlock(&sctx->stat_lock);
861                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_READ_ERRS);
862                 goto out;
863         }
864
865         /* setup the context, map the logical blocks and alloc the pages */
866         ret = scrub_setup_recheck_block(sctx, fs_info, sblock_to_check, length,
867                                         logical, sblocks_for_recheck);
868         if (ret) {
869                 spin_lock(&sctx->stat_lock);
870                 sctx->stat.read_errors++;
871                 sctx->stat.uncorrectable_errors++;
872                 spin_unlock(&sctx->stat_lock);
873                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_READ_ERRS);
874                 goto out;
875         }
876         BUG_ON(failed_mirror_index >= BTRFS_MAX_MIRRORS);
877         sblock_bad = sblocks_for_recheck + failed_mirror_index;
878
879         /* build and submit the bios for the failed mirror, check checksums */
880         scrub_recheck_block(fs_info, sblock_bad, is_metadata, have_csum,
881                             csum, generation, sctx->csum_size);
882
883         if (!sblock_bad->header_error && !sblock_bad->checksum_error &&
884             sblock_bad->no_io_error_seen) {
885                 /*
886                  * the error disappeared after reading page by page, or
887                  * the area was part of a huge bio and other parts of the
888                  * bio caused I/O errors, or the block layer merged several
889                  * read requests into one and the error is caused by a
890                  * different bio (usually one of the two latter cases is
891                  * the cause)
892                  */
893                 spin_lock(&sctx->stat_lock);
894                 sctx->stat.unverified_errors++;
895                 spin_unlock(&sctx->stat_lock);
896
897                 if (sctx->is_dev_replace)
898                         scrub_write_block_to_dev_replace(sblock_bad);
899                 goto out;
900         }
901
902         if (!sblock_bad->no_io_error_seen) {
903                 spin_lock(&sctx->stat_lock);
904                 sctx->stat.read_errors++;
905                 spin_unlock(&sctx->stat_lock);
906                 if (__ratelimit(&_rs))
907                         scrub_print_warning("i/o error", sblock_to_check);
908                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_READ_ERRS);
909         } else if (sblock_bad->checksum_error) {
910                 spin_lock(&sctx->stat_lock);
911                 sctx->stat.csum_errors++;
912                 spin_unlock(&sctx->stat_lock);
913                 if (__ratelimit(&_rs))
914                         scrub_print_warning("checksum error", sblock_to_check);
915                 btrfs_dev_stat_inc_and_print(dev,
916                                              BTRFS_DEV_STAT_CORRUPTION_ERRS);
917         } else if (sblock_bad->header_error) {
918                 spin_lock(&sctx->stat_lock);
919                 sctx->stat.verify_errors++;
920                 spin_unlock(&sctx->stat_lock);
921                 if (__ratelimit(&_rs))
922                         scrub_print_warning("checksum/header error",
923                                             sblock_to_check);
924                 if (sblock_bad->generation_error)
925                         btrfs_dev_stat_inc_and_print(dev,
926                                 BTRFS_DEV_STAT_GENERATION_ERRS);
927                 else
928                         btrfs_dev_stat_inc_and_print(dev,
929                                 BTRFS_DEV_STAT_CORRUPTION_ERRS);
930         }
931
932         if (sctx->readonly && !sctx->is_dev_replace)
933                 goto did_not_correct_error;
934
935         if (!is_metadata && !have_csum) {
936                 struct scrub_fixup_nodatasum *fixup_nodatasum;
937
938 nodatasum_case:
939                 WARN_ON(sctx->is_dev_replace);
940
941                 /*
942                  * !is_metadata and !have_csum, this means that the data
943                  * might not be COW'ed, that it might be modified
944                  * concurrently. The general strategy to work on the
945                  * commit root does not help in the case when COW is not
946                  * used.
947                  */
948                 fixup_nodatasum = kzalloc(sizeof(*fixup_nodatasum), GFP_NOFS);
949                 if (!fixup_nodatasum)
950                         goto did_not_correct_error;
951                 fixup_nodatasum->sctx = sctx;
952                 fixup_nodatasum->dev = dev;
953                 fixup_nodatasum->logical = logical;
954                 fixup_nodatasum->root = fs_info->extent_root;
955                 fixup_nodatasum->mirror_num = failed_mirror_index + 1;
956                 scrub_pending_trans_workers_inc(sctx);
957                 fixup_nodatasum->work.func = scrub_fixup_nodatasum;
958                 btrfs_queue_worker(&fs_info->scrub_workers,
959                                    &fixup_nodatasum->work);
960                 goto out;
961         }
962
963         /*
964          * now build and submit the bios for the other mirrors, check
965          * checksums.
966          * First try to pick the mirror which is completely without I/O
967          * errors and also does not have a checksum error.
968          * If one is found, and if a checksum is present, the full block
969          * that is known to contain an error is rewritten. Afterwards
970          * the block is known to be corrected.
971          * If a mirror is found which is completely correct, and no
972          * checksum is present, only those pages are rewritten that had
973          * an I/O error in the block to be repaired, since it cannot be
974          * determined, which copy of the other pages is better (and it
975          * could happen otherwise that a correct page would be
976          * overwritten by a bad one).
977          */
978         for (mirror_index = 0;
979              mirror_index < BTRFS_MAX_MIRRORS &&
980              sblocks_for_recheck[mirror_index].page_count > 0;
981              mirror_index++) {
982                 struct scrub_block *sblock_other;
983
984                 if (mirror_index == failed_mirror_index)
985                         continue;
986                 sblock_other = sblocks_for_recheck + mirror_index;
987
988                 /* build and submit the bios, check checksums */
989                 scrub_recheck_block(fs_info, sblock_other, is_metadata,
990                                     have_csum, csum, generation,
991                                     sctx->csum_size);
992
993                 if (!sblock_other->header_error &&
994                     !sblock_other->checksum_error &&
995                     sblock_other->no_io_error_seen) {
996                         if (sctx->is_dev_replace) {
997                                 scrub_write_block_to_dev_replace(sblock_other);
998                         } else {
999                                 int force_write = is_metadata || have_csum;
1000
1001                                 ret = scrub_repair_block_from_good_copy(
1002                                                 sblock_bad, sblock_other,
1003                                                 force_write);
1004                         }
1005                         if (0 == ret)
1006                                 goto corrected_error;
1007                 }
1008         }
1009
1010         /*
1011          * for dev_replace, pick good pages and write to the target device.
1012          */
1013         if (sctx->is_dev_replace) {
1014                 success = 1;
1015                 for (page_num = 0; page_num < sblock_bad->page_count;
1016                      page_num++) {
1017                         int sub_success;
1018
1019                         sub_success = 0;
1020                         for (mirror_index = 0;
1021                              mirror_index < BTRFS_MAX_MIRRORS &&
1022                              sblocks_for_recheck[mirror_index].page_count > 0;
1023                              mirror_index++) {
1024                                 struct scrub_block *sblock_other =
1025                                         sblocks_for_recheck + mirror_index;
1026                                 struct scrub_page *page_other =
1027                                         sblock_other->pagev[page_num];
1028
1029                                 if (!page_other->io_error) {
1030                                         ret = scrub_write_page_to_dev_replace(
1031                                                         sblock_other, page_num);
1032                                         if (ret == 0) {
1033                                                 /* succeeded for this page */
1034                                                 sub_success = 1;
1035                                                 break;
1036                                         } else {
1037                                                 btrfs_dev_replace_stats_inc(
1038                                                         &sctx->dev_root->
1039                                                         fs_info->dev_replace.
1040                                                         num_write_errors);
1041                                         }
1042                                 }
1043                         }
1044
1045                         if (!sub_success) {
1046                                 /*
1047                                  * did not find a mirror to fetch the page
1048                                  * from. scrub_write_page_to_dev_replace()
1049                                  * handles this case (page->io_error), by
1050                                  * filling the block with zeros before
1051                                  * submitting the write request
1052                                  */
1053                                 success = 0;
1054                                 ret = scrub_write_page_to_dev_replace(
1055                                                 sblock_bad, page_num);
1056                                 if (ret)
1057                                         btrfs_dev_replace_stats_inc(
1058                                                 &sctx->dev_root->fs_info->
1059                                                 dev_replace.num_write_errors);
1060                         }
1061                 }
1062
1063                 goto out;
1064         }
1065
1066         /*
1067          * for regular scrub, repair those pages that are errored.
1068          * In case of I/O errors in the area that is supposed to be
1069          * repaired, continue by picking good copies of those pages.
1070          * Select the good pages from mirrors to rewrite bad pages from
1071          * the area to fix. Afterwards verify the checksum of the block
1072          * that is supposed to be repaired. This verification step is
1073          * only done for the purpose of statistic counting and for the
1074          * final scrub report, whether errors remain.
1075          * A perfect algorithm could make use of the checksum and try
1076          * all possible combinations of pages from the different mirrors
1077          * until the checksum verification succeeds. For example, when
1078          * the 2nd page of mirror #1 faces I/O errors, and the 2nd page
1079          * of mirror #2 is readable but the final checksum test fails,
1080          * then the 2nd page of mirror #3 could be tried, whether now
1081          * the final checksum succeedes. But this would be a rare
1082          * exception and is therefore not implemented. At least it is
1083          * avoided that the good copy is overwritten.
1084          * A more useful improvement would be to pick the sectors
1085          * without I/O error based on sector sizes (512 bytes on legacy
1086          * disks) instead of on PAGE_SIZE. Then maybe 512 byte of one
1087          * mirror could be repaired by taking 512 byte of a different
1088          * mirror, even if other 512 byte sectors in the same PAGE_SIZE
1089          * area are unreadable.
1090          */
1091
1092         /* can only fix I/O errors from here on */
1093         if (sblock_bad->no_io_error_seen)
1094                 goto did_not_correct_error;
1095
1096         success = 1;
1097         for (page_num = 0; page_num < sblock_bad->page_count; page_num++) {
1098                 struct scrub_page *page_bad = sblock_bad->pagev[page_num];
1099
1100                 if (!page_bad->io_error)
1101                         continue;
1102
1103                 for (mirror_index = 0;
1104                      mirror_index < BTRFS_MAX_MIRRORS &&
1105                      sblocks_for_recheck[mirror_index].page_count > 0;
1106                      mirror_index++) {
1107                         struct scrub_block *sblock_other = sblocks_for_recheck +
1108                                                            mirror_index;
1109                         struct scrub_page *page_other = sblock_other->pagev[
1110                                                         page_num];
1111
1112                         if (!page_other->io_error) {
1113                                 ret = scrub_repair_page_from_good_copy(
1114                                         sblock_bad, sblock_other, page_num, 0);
1115                                 if (0 == ret) {
1116                                         page_bad->io_error = 0;
1117                                         break; /* succeeded for this page */
1118                                 }
1119                         }
1120                 }
1121
1122                 if (page_bad->io_error) {
1123                         /* did not find a mirror to copy the page from */
1124                         success = 0;
1125                 }
1126         }
1127
1128         if (success) {
1129                 if (is_metadata || have_csum) {
1130                         /*
1131                          * need to verify the checksum now that all
1132                          * sectors on disk are repaired (the write
1133                          * request for data to be repaired is on its way).
1134                          * Just be lazy and use scrub_recheck_block()
1135                          * which re-reads the data before the checksum
1136                          * is verified, but most likely the data comes out
1137                          * of the page cache.
1138                          */
1139                         scrub_recheck_block(fs_info, sblock_bad,
1140                                             is_metadata, have_csum, csum,
1141                                             generation, sctx->csum_size);
1142                         if (!sblock_bad->header_error &&
1143                             !sblock_bad->checksum_error &&
1144                             sblock_bad->no_io_error_seen)
1145                                 goto corrected_error;
1146                         else
1147                                 goto did_not_correct_error;
1148                 } else {
1149 corrected_error:
1150                         spin_lock(&sctx->stat_lock);
1151                         sctx->stat.corrected_errors++;
1152                         spin_unlock(&sctx->stat_lock);
1153                         printk_ratelimited_in_rcu(KERN_ERR
1154                                 "btrfs: fixed up error at logical %llu on dev %s\n",
1155                                 (unsigned long long)logical,
1156                                 rcu_str_deref(dev->name));
1157                 }
1158         } else {
1159 did_not_correct_error:
1160                 spin_lock(&sctx->stat_lock);
1161                 sctx->stat.uncorrectable_errors++;
1162                 spin_unlock(&sctx->stat_lock);
1163                 printk_ratelimited_in_rcu(KERN_ERR
1164                         "btrfs: unable to fixup (regular) error at logical %llu on dev %s\n",
1165                         (unsigned long long)logical,
1166                         rcu_str_deref(dev->name));
1167         }
1168
1169 out:
1170         if (sblocks_for_recheck) {
1171                 for (mirror_index = 0; mirror_index < BTRFS_MAX_MIRRORS;
1172                      mirror_index++) {
1173                         struct scrub_block *sblock = sblocks_for_recheck +
1174                                                      mirror_index;
1175                         int page_index;
1176
1177                         for (page_index = 0; page_index < sblock->page_count;
1178                              page_index++) {
1179                                 sblock->pagev[page_index]->sblock = NULL;
1180                                 scrub_page_put(sblock->pagev[page_index]);
1181                         }
1182                 }
1183                 kfree(sblocks_for_recheck);
1184         }
1185
1186         return 0;
1187 }
1188
1189 static int scrub_setup_recheck_block(struct scrub_ctx *sctx,
1190                                      struct btrfs_fs_info *fs_info,
1191                                      struct scrub_block *original_sblock,
1192                                      u64 length, u64 logical,
1193                                      struct scrub_block *sblocks_for_recheck)
1194 {
1195         int page_index;
1196         int mirror_index;
1197         int ret;
1198
1199         /*
1200          * note: the two members ref_count and outstanding_pages
1201          * are not used (and not set) in the blocks that are used for
1202          * the recheck procedure
1203          */
1204
1205         page_index = 0;
1206         while (length > 0) {
1207                 u64 sublen = min_t(u64, length, PAGE_SIZE);
1208                 u64 mapped_length = sublen;
1209                 struct btrfs_bio *bbio = NULL;
1210
1211                 /*
1212                  * with a length of PAGE_SIZE, each returned stripe
1213                  * represents one mirror
1214                  */
1215                 ret = btrfs_map_block(fs_info, REQ_GET_READ_MIRRORS, logical,
1216                                       &mapped_length, &bbio, 0);
1217                 if (ret || !bbio || mapped_length < sublen) {
1218                         kfree(bbio);
1219                         return -EIO;
1220                 }
1221
1222                 BUG_ON(page_index >= SCRUB_PAGES_PER_RD_BIO);
1223                 for (mirror_index = 0; mirror_index < (int)bbio->num_stripes;
1224                      mirror_index++) {
1225                         struct scrub_block *sblock;
1226                         struct scrub_page *page;
1227
1228                         if (mirror_index >= BTRFS_MAX_MIRRORS)
1229                                 continue;
1230
1231                         sblock = sblocks_for_recheck + mirror_index;
1232                         sblock->sctx = sctx;
1233                         page = kzalloc(sizeof(*page), GFP_NOFS);
1234                         if (!page) {
1235 leave_nomem:
1236                                 spin_lock(&sctx->stat_lock);
1237                                 sctx->stat.malloc_errors++;
1238                                 spin_unlock(&sctx->stat_lock);
1239                                 kfree(bbio);
1240                                 return -ENOMEM;
1241                         }
1242                         scrub_page_get(page);
1243                         sblock->pagev[page_index] = page;
1244                         page->logical = logical;
1245                         page->physical = bbio->stripes[mirror_index].physical;
1246                         BUG_ON(page_index >= original_sblock->page_count);
1247                         page->physical_for_dev_replace =
1248                                 original_sblock->pagev[page_index]->
1249                                 physical_for_dev_replace;
1250                         /* for missing devices, dev->bdev is NULL */
1251                         page->dev = bbio->stripes[mirror_index].dev;
1252                         page->mirror_num = mirror_index + 1;
1253                         sblock->page_count++;
1254                         page->page = alloc_page(GFP_NOFS);
1255                         if (!page->page)
1256                                 goto leave_nomem;
1257                 }
1258                 kfree(bbio);
1259                 length -= sublen;
1260                 logical += sublen;
1261                 page_index++;
1262         }
1263
1264         return 0;
1265 }
1266
1267 /*
1268  * this function will check the on disk data for checksum errors, header
1269  * errors and read I/O errors. If any I/O errors happen, the exact pages
1270  * which are errored are marked as being bad. The goal is to enable scrub
1271  * to take those pages that are not errored from all the mirrors so that
1272  * the pages that are errored in the just handled mirror can be repaired.
1273  */
1274 static void scrub_recheck_block(struct btrfs_fs_info *fs_info,
1275                                 struct scrub_block *sblock, int is_metadata,
1276                                 int have_csum, u8 *csum, u64 generation,
1277                                 u16 csum_size)
1278 {
1279         int page_num;
1280
1281         sblock->no_io_error_seen = 1;
1282         sblock->header_error = 0;
1283         sblock->checksum_error = 0;
1284
1285         for (page_num = 0; page_num < sblock->page_count; page_num++) {
1286                 struct bio *bio;
1287                 struct scrub_page *page = sblock->pagev[page_num];
1288                 DECLARE_COMPLETION_ONSTACK(complete);
1289
1290                 if (page->dev->bdev == NULL) {
1291                         page->io_error = 1;
1292                         sblock->no_io_error_seen = 0;
1293                         continue;
1294                 }
1295
1296                 WARN_ON(!page->page);
1297                 bio = bio_alloc(GFP_NOFS, 1);
1298                 if (!bio) {
1299                         page->io_error = 1;
1300                         sblock->no_io_error_seen = 0;
1301                         continue;
1302                 }
1303                 bio->bi_bdev = page->dev->bdev;
1304                 bio->bi_sector = page->physical >> 9;
1305                 bio->bi_end_io = scrub_complete_bio_end_io;
1306                 bio->bi_private = &complete;
1307
1308                 bio_add_page(bio, page->page, PAGE_SIZE, 0);
1309                 btrfsic_submit_bio(READ, bio);
1310
1311                 /* this will also unplug the queue */
1312                 wait_for_completion(&complete);
1313
1314                 page->io_error = !test_bit(BIO_UPTODATE, &bio->bi_flags);
1315                 if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
1316                         sblock->no_io_error_seen = 0;
1317                 bio_put(bio);
1318         }
1319
1320         if (sblock->no_io_error_seen)
1321                 scrub_recheck_block_checksum(fs_info, sblock, is_metadata,
1322                                              have_csum, csum, generation,
1323                                              csum_size);
1324
1325         return;
1326 }
1327
1328 static void scrub_recheck_block_checksum(struct btrfs_fs_info *fs_info,
1329                                          struct scrub_block *sblock,
1330                                          int is_metadata, int have_csum,
1331                                          const u8 *csum, u64 generation,
1332                                          u16 csum_size)
1333 {
1334         int page_num;
1335         u8 calculated_csum[BTRFS_CSUM_SIZE];
1336         u32 crc = ~(u32)0;
1337         struct btrfs_root *root = fs_info->extent_root;
1338         void *mapped_buffer;
1339
1340         WARN_ON(!sblock->pagev[0]->page);
1341         if (is_metadata) {
1342                 struct btrfs_header *h;
1343
1344                 mapped_buffer = kmap_atomic(sblock->pagev[0]->page);
1345                 h = (struct btrfs_header *)mapped_buffer;
1346
1347                 if (sblock->pagev[0]->logical != le64_to_cpu(h->bytenr) ||
1348                     memcmp(h->fsid, fs_info->fsid, BTRFS_UUID_SIZE) ||
1349                     memcmp(h->chunk_tree_uuid, fs_info->chunk_tree_uuid,
1350                            BTRFS_UUID_SIZE)) {
1351                         sblock->header_error = 1;
1352                 } else if (generation != le64_to_cpu(h->generation)) {
1353                         sblock->header_error = 1;
1354                         sblock->generation_error = 1;
1355                 }
1356                 csum = h->csum;
1357         } else {
1358                 if (!have_csum)
1359                         return;
1360
1361                 mapped_buffer = kmap_atomic(sblock->pagev[0]->page);
1362         }
1363
1364         for (page_num = 0;;) {
1365                 if (page_num == 0 && is_metadata)
1366                         crc = btrfs_csum_data(root,
1367                                 ((u8 *)mapped_buffer) + BTRFS_CSUM_SIZE,
1368                                 crc, PAGE_SIZE - BTRFS_CSUM_SIZE);
1369                 else
1370                         crc = btrfs_csum_data(root, mapped_buffer, crc,
1371                                               PAGE_SIZE);
1372
1373                 kunmap_atomic(mapped_buffer);
1374                 page_num++;
1375                 if (page_num >= sblock->page_count)
1376                         break;
1377                 WARN_ON(!sblock->pagev[page_num]->page);
1378
1379                 mapped_buffer = kmap_atomic(sblock->pagev[page_num]->page);
1380         }
1381
1382         btrfs_csum_final(crc, calculated_csum);
1383         if (memcmp(calculated_csum, csum, csum_size))
1384                 sblock->checksum_error = 1;
1385 }
1386
1387 static void scrub_complete_bio_end_io(struct bio *bio, int err)
1388 {
1389         complete((struct completion *)bio->bi_private);
1390 }
1391
1392 static int scrub_repair_block_from_good_copy(struct scrub_block *sblock_bad,
1393                                              struct scrub_block *sblock_good,
1394                                              int force_write)
1395 {
1396         int page_num;
1397         int ret = 0;
1398
1399         for (page_num = 0; page_num < sblock_bad->page_count; page_num++) {
1400                 int ret_sub;
1401
1402                 ret_sub = scrub_repair_page_from_good_copy(sblock_bad,
1403                                                            sblock_good,
1404                                                            page_num,
1405                                                            force_write);
1406                 if (ret_sub)
1407                         ret = ret_sub;
1408         }
1409
1410         return ret;
1411 }
1412
1413 static int scrub_repair_page_from_good_copy(struct scrub_block *sblock_bad,
1414                                             struct scrub_block *sblock_good,
1415                                             int page_num, int force_write)
1416 {
1417         struct scrub_page *page_bad = sblock_bad->pagev[page_num];
1418         struct scrub_page *page_good = sblock_good->pagev[page_num];
1419
1420         BUG_ON(page_bad->page == NULL);
1421         BUG_ON(page_good->page == NULL);
1422         if (force_write || sblock_bad->header_error ||
1423             sblock_bad->checksum_error || page_bad->io_error) {
1424                 struct bio *bio;
1425                 int ret;
1426                 DECLARE_COMPLETION_ONSTACK(complete);
1427
1428                 if (!page_bad->dev->bdev) {
1429                         printk_ratelimited(KERN_WARNING
1430                                 "btrfs: scrub_repair_page_from_good_copy(bdev == NULL) is unexpected!\n");
1431                         return -EIO;
1432                 }
1433
1434                 bio = bio_alloc(GFP_NOFS, 1);
1435                 if (!bio)
1436                         return -EIO;
1437                 bio->bi_bdev = page_bad->dev->bdev;
1438                 bio->bi_sector = page_bad->physical >> 9;
1439                 bio->bi_end_io = scrub_complete_bio_end_io;
1440                 bio->bi_private = &complete;
1441
1442                 ret = bio_add_page(bio, page_good->page, PAGE_SIZE, 0);
1443                 if (PAGE_SIZE != ret) {
1444                         bio_put(bio);
1445                         return -EIO;
1446                 }
1447                 btrfsic_submit_bio(WRITE, bio);
1448
1449                 /* this will also unplug the queue */
1450                 wait_for_completion(&complete);
1451                 if (!bio_flagged(bio, BIO_UPTODATE)) {
1452                         btrfs_dev_stat_inc_and_print(page_bad->dev,
1453                                 BTRFS_DEV_STAT_WRITE_ERRS);
1454                         btrfs_dev_replace_stats_inc(
1455                                 &sblock_bad->sctx->dev_root->fs_info->
1456                                 dev_replace.num_write_errors);
1457                         bio_put(bio);
1458                         return -EIO;
1459                 }
1460                 bio_put(bio);
1461         }
1462
1463         return 0;
1464 }
1465
1466 static void scrub_write_block_to_dev_replace(struct scrub_block *sblock)
1467 {
1468         int page_num;
1469
1470         for (page_num = 0; page_num < sblock->page_count; page_num++) {
1471                 int ret;
1472
1473                 ret = scrub_write_page_to_dev_replace(sblock, page_num);
1474                 if (ret)
1475                         btrfs_dev_replace_stats_inc(
1476                                 &sblock->sctx->dev_root->fs_info->dev_replace.
1477                                 num_write_errors);
1478         }
1479 }
1480
1481 static int scrub_write_page_to_dev_replace(struct scrub_block *sblock,
1482                                            int page_num)
1483 {
1484         struct scrub_page *spage = sblock->pagev[page_num];
1485
1486         BUG_ON(spage->page == NULL);
1487         if (spage->io_error) {
1488                 void *mapped_buffer = kmap_atomic(spage->page);
1489
1490                 memset(mapped_buffer, 0, PAGE_CACHE_SIZE);
1491                 flush_dcache_page(spage->page);
1492                 kunmap_atomic(mapped_buffer);
1493         }
1494         return scrub_add_page_to_wr_bio(sblock->sctx, spage);
1495 }
1496
1497 static int scrub_add_page_to_wr_bio(struct scrub_ctx *sctx,
1498                                     struct scrub_page *spage)
1499 {
1500         struct scrub_wr_ctx *wr_ctx = &sctx->wr_ctx;
1501         struct scrub_bio *sbio;
1502         int ret;
1503
1504         mutex_lock(&wr_ctx->wr_lock);
1505 again:
1506         if (!wr_ctx->wr_curr_bio) {
1507                 wr_ctx->wr_curr_bio = kzalloc(sizeof(*wr_ctx->wr_curr_bio),
1508                                               GFP_NOFS);
1509                 if (!wr_ctx->wr_curr_bio) {
1510                         mutex_unlock(&wr_ctx->wr_lock);
1511                         return -ENOMEM;
1512                 }
1513                 wr_ctx->wr_curr_bio->sctx = sctx;
1514                 wr_ctx->wr_curr_bio->page_count = 0;
1515         }
1516         sbio = wr_ctx->wr_curr_bio;
1517         if (sbio->page_count == 0) {
1518                 struct bio *bio;
1519
1520                 sbio->physical = spage->physical_for_dev_replace;
1521                 sbio->logical = spage->logical;
1522                 sbio->dev = wr_ctx->tgtdev;
1523                 bio = sbio->bio;
1524                 if (!bio) {
1525                         bio = bio_alloc(GFP_NOFS, wr_ctx->pages_per_wr_bio);
1526                         if (!bio) {
1527                                 mutex_unlock(&wr_ctx->wr_lock);
1528                                 return -ENOMEM;
1529                         }
1530                         sbio->bio = bio;
1531                 }
1532
1533                 bio->bi_private = sbio;
1534                 bio->bi_end_io = scrub_wr_bio_end_io;
1535                 bio->bi_bdev = sbio->dev->bdev;
1536                 bio->bi_sector = sbio->physical >> 9;
1537                 sbio->err = 0;
1538         } else if (sbio->physical + sbio->page_count * PAGE_SIZE !=
1539                    spage->physical_for_dev_replace ||
1540                    sbio->logical + sbio->page_count * PAGE_SIZE !=
1541                    spage->logical) {
1542                 scrub_wr_submit(sctx);
1543                 goto again;
1544         }
1545
1546         ret = bio_add_page(sbio->bio, spage->page, PAGE_SIZE, 0);
1547         if (ret != PAGE_SIZE) {
1548                 if (sbio->page_count < 1) {
1549                         bio_put(sbio->bio);
1550                         sbio->bio = NULL;
1551                         mutex_unlock(&wr_ctx->wr_lock);
1552                         return -EIO;
1553                 }
1554                 scrub_wr_submit(sctx);
1555                 goto again;
1556         }
1557
1558         sbio->pagev[sbio->page_count] = spage;
1559         scrub_page_get(spage);
1560         sbio->page_count++;
1561         if (sbio->page_count == wr_ctx->pages_per_wr_bio)
1562                 scrub_wr_submit(sctx);
1563         mutex_unlock(&wr_ctx->wr_lock);
1564
1565         return 0;
1566 }
1567
1568 static void scrub_wr_submit(struct scrub_ctx *sctx)
1569 {
1570         struct scrub_wr_ctx *wr_ctx = &sctx->wr_ctx;
1571         struct scrub_bio *sbio;
1572
1573         if (!wr_ctx->wr_curr_bio)
1574                 return;
1575
1576         sbio = wr_ctx->wr_curr_bio;
1577         wr_ctx->wr_curr_bio = NULL;
1578         WARN_ON(!sbio->bio->bi_bdev);
1579         scrub_pending_bio_inc(sctx);
1580         /* process all writes in a single worker thread. Then the block layer
1581          * orders the requests before sending them to the driver which
1582          * doubled the write performance on spinning disks when measured
1583          * with Linux 3.5 */
1584         btrfsic_submit_bio(WRITE, sbio->bio);
1585 }
1586
1587 static void scrub_wr_bio_end_io(struct bio *bio, int err)
1588 {
1589         struct scrub_bio *sbio = bio->bi_private;
1590         struct btrfs_fs_info *fs_info = sbio->dev->dev_root->fs_info;
1591
1592         sbio->err = err;
1593         sbio->bio = bio;
1594
1595         sbio->work.func = scrub_wr_bio_end_io_worker;
1596         btrfs_queue_worker(&fs_info->scrub_wr_completion_workers, &sbio->work);
1597 }
1598
1599 static void scrub_wr_bio_end_io_worker(struct btrfs_work *work)
1600 {
1601         struct scrub_bio *sbio = container_of(work, struct scrub_bio, work);
1602         struct scrub_ctx *sctx = sbio->sctx;
1603         int i;
1604
1605         WARN_ON(sbio->page_count > SCRUB_PAGES_PER_WR_BIO);
1606         if (sbio->err) {
1607                 struct btrfs_dev_replace *dev_replace =
1608                         &sbio->sctx->dev_root->fs_info->dev_replace;
1609
1610                 for (i = 0; i < sbio->page_count; i++) {
1611                         struct scrub_page *spage = sbio->pagev[i];
1612
1613                         spage->io_error = 1;
1614                         btrfs_dev_replace_stats_inc(&dev_replace->
1615                                                     num_write_errors);
1616                 }
1617         }
1618
1619         for (i = 0; i < sbio->page_count; i++)
1620                 scrub_page_put(sbio->pagev[i]);
1621
1622         bio_put(sbio->bio);
1623         kfree(sbio);
1624         scrub_pending_bio_dec(sctx);
1625 }
1626
1627 static int scrub_checksum(struct scrub_block *sblock)
1628 {
1629         u64 flags;
1630         int ret;
1631
1632         WARN_ON(sblock->page_count < 1);
1633         flags = sblock->pagev[0]->flags;
1634         ret = 0;
1635         if (flags & BTRFS_EXTENT_FLAG_DATA)
1636                 ret = scrub_checksum_data(sblock);
1637         else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
1638                 ret = scrub_checksum_tree_block(sblock);
1639         else if (flags & BTRFS_EXTENT_FLAG_SUPER)
1640                 (void)scrub_checksum_super(sblock);
1641         else
1642                 WARN_ON(1);
1643         if (ret)
1644                 scrub_handle_errored_block(sblock);
1645
1646         return ret;
1647 }
1648
1649 static int scrub_checksum_data(struct scrub_block *sblock)
1650 {
1651         struct scrub_ctx *sctx = sblock->sctx;
1652         u8 csum[BTRFS_CSUM_SIZE];
1653         u8 *on_disk_csum;
1654         struct page *page;
1655         void *buffer;
1656         u32 crc = ~(u32)0;
1657         int fail = 0;
1658         struct btrfs_root *root = sctx->dev_root;
1659         u64 len;
1660         int index;
1661
1662         BUG_ON(sblock->page_count < 1);
1663         if (!sblock->pagev[0]->have_csum)
1664                 return 0;
1665
1666         on_disk_csum = sblock->pagev[0]->csum;
1667         page = sblock->pagev[0]->page;
1668         buffer = kmap_atomic(page);
1669
1670         len = sctx->sectorsize;
1671         index = 0;
1672         for (;;) {
1673                 u64 l = min_t(u64, len, PAGE_SIZE);
1674
1675                 crc = btrfs_csum_data(root, buffer, crc, l);
1676                 kunmap_atomic(buffer);
1677                 len -= l;
1678                 if (len == 0)
1679                         break;
1680                 index++;
1681                 BUG_ON(index >= sblock->page_count);
1682                 BUG_ON(!sblock->pagev[index]->page);
1683                 page = sblock->pagev[index]->page;
1684                 buffer = kmap_atomic(page);
1685         }
1686
1687         btrfs_csum_final(crc, csum);
1688         if (memcmp(csum, on_disk_csum, sctx->csum_size))
1689                 fail = 1;
1690
1691         return fail;
1692 }
1693
1694 static int scrub_checksum_tree_block(struct scrub_block *sblock)
1695 {
1696         struct scrub_ctx *sctx = sblock->sctx;
1697         struct btrfs_header *h;
1698         struct btrfs_root *root = sctx->dev_root;
1699         struct btrfs_fs_info *fs_info = root->fs_info;
1700         u8 calculated_csum[BTRFS_CSUM_SIZE];
1701         u8 on_disk_csum[BTRFS_CSUM_SIZE];
1702         struct page *page;
1703         void *mapped_buffer;
1704         u64 mapped_size;
1705         void *p;
1706         u32 crc = ~(u32)0;
1707         int fail = 0;
1708         int crc_fail = 0;
1709         u64 len;
1710         int index;
1711
1712         BUG_ON(sblock->page_count < 1);
1713         page = sblock->pagev[0]->page;
1714         mapped_buffer = kmap_atomic(page);
1715         h = (struct btrfs_header *)mapped_buffer;
1716         memcpy(on_disk_csum, h->csum, sctx->csum_size);
1717
1718         /*
1719          * we don't use the getter functions here, as we
1720          * a) don't have an extent buffer and
1721          * b) the page is already kmapped
1722          */
1723
1724         if (sblock->pagev[0]->logical != le64_to_cpu(h->bytenr))
1725                 ++fail;
1726
1727         if (sblock->pagev[0]->generation != le64_to_cpu(h->generation))
1728                 ++fail;
1729
1730         if (memcmp(h->fsid, fs_info->fsid, BTRFS_UUID_SIZE))
1731                 ++fail;
1732
1733         if (memcmp(h->chunk_tree_uuid, fs_info->chunk_tree_uuid,
1734                    BTRFS_UUID_SIZE))
1735                 ++fail;
1736
1737         WARN_ON(sctx->nodesize != sctx->leafsize);
1738         len = sctx->nodesize - BTRFS_CSUM_SIZE;
1739         mapped_size = PAGE_SIZE - BTRFS_CSUM_SIZE;
1740         p = ((u8 *)mapped_buffer) + BTRFS_CSUM_SIZE;
1741         index = 0;
1742         for (;;) {
1743                 u64 l = min_t(u64, len, mapped_size);
1744
1745                 crc = btrfs_csum_data(root, p, crc, l);
1746                 kunmap_atomic(mapped_buffer);
1747                 len -= l;
1748                 if (len == 0)
1749                         break;
1750                 index++;
1751                 BUG_ON(index >= sblock->page_count);
1752                 BUG_ON(!sblock->pagev[index]->page);
1753                 page = sblock->pagev[index]->page;
1754                 mapped_buffer = kmap_atomic(page);
1755                 mapped_size = PAGE_SIZE;
1756                 p = mapped_buffer;
1757         }
1758
1759         btrfs_csum_final(crc, calculated_csum);
1760         if (memcmp(calculated_csum, on_disk_csum, sctx->csum_size))
1761                 ++crc_fail;
1762
1763         return fail || crc_fail;
1764 }
1765
1766 static int scrub_checksum_super(struct scrub_block *sblock)
1767 {
1768         struct btrfs_super_block *s;
1769         struct scrub_ctx *sctx = sblock->sctx;
1770         struct btrfs_root *root = sctx->dev_root;
1771         struct btrfs_fs_info *fs_info = root->fs_info;
1772         u8 calculated_csum[BTRFS_CSUM_SIZE];
1773         u8 on_disk_csum[BTRFS_CSUM_SIZE];
1774         struct page *page;
1775         void *mapped_buffer;
1776         u64 mapped_size;
1777         void *p;
1778         u32 crc = ~(u32)0;
1779         int fail_gen = 0;
1780         int fail_cor = 0;
1781         u64 len;
1782         int index;
1783
1784         BUG_ON(sblock->page_count < 1);
1785         page = sblock->pagev[0]->page;
1786         mapped_buffer = kmap_atomic(page);
1787         s = (struct btrfs_super_block *)mapped_buffer;
1788         memcpy(on_disk_csum, s->csum, sctx->csum_size);
1789
1790         if (sblock->pagev[0]->logical != le64_to_cpu(s->bytenr))
1791                 ++fail_cor;
1792
1793         if (sblock->pagev[0]->generation != le64_to_cpu(s->generation))
1794                 ++fail_gen;
1795
1796         if (memcmp(s->fsid, fs_info->fsid, BTRFS_UUID_SIZE))
1797                 ++fail_cor;
1798
1799         len = BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE;
1800         mapped_size = PAGE_SIZE - BTRFS_CSUM_SIZE;
1801         p = ((u8 *)mapped_buffer) + BTRFS_CSUM_SIZE;
1802         index = 0;
1803         for (;;) {
1804                 u64 l = min_t(u64, len, mapped_size);
1805
1806                 crc = btrfs_csum_data(root, p, crc, l);
1807                 kunmap_atomic(mapped_buffer);
1808                 len -= l;
1809                 if (len == 0)
1810                         break;
1811                 index++;
1812                 BUG_ON(index >= sblock->page_count);
1813                 BUG_ON(!sblock->pagev[index]->page);
1814                 page = sblock->pagev[index]->page;
1815                 mapped_buffer = kmap_atomic(page);
1816                 mapped_size = PAGE_SIZE;
1817                 p = mapped_buffer;
1818         }
1819
1820         btrfs_csum_final(crc, calculated_csum);
1821         if (memcmp(calculated_csum, on_disk_csum, sctx->csum_size))
1822                 ++fail_cor;
1823
1824         if (fail_cor + fail_gen) {
1825                 /*
1826                  * if we find an error in a super block, we just report it.
1827                  * They will get written with the next transaction commit
1828                  * anyway
1829                  */
1830                 spin_lock(&sctx->stat_lock);
1831                 ++sctx->stat.super_errors;
1832                 spin_unlock(&sctx->stat_lock);
1833                 if (fail_cor)
1834                         btrfs_dev_stat_inc_and_print(sblock->pagev[0]->dev,
1835                                 BTRFS_DEV_STAT_CORRUPTION_ERRS);
1836                 else
1837                         btrfs_dev_stat_inc_and_print(sblock->pagev[0]->dev,
1838                                 BTRFS_DEV_STAT_GENERATION_ERRS);
1839         }
1840
1841         return fail_cor + fail_gen;
1842 }
1843
1844 static void scrub_block_get(struct scrub_block *sblock)
1845 {
1846         atomic_inc(&sblock->ref_count);
1847 }
1848
1849 static void scrub_block_put(struct scrub_block *sblock)
1850 {
1851         if (atomic_dec_and_test(&sblock->ref_count)) {
1852                 int i;
1853
1854                 for (i = 0; i < sblock->page_count; i++)
1855                         scrub_page_put(sblock->pagev[i]);
1856                 kfree(sblock);
1857         }
1858 }
1859
1860 static void scrub_page_get(struct scrub_page *spage)
1861 {
1862         atomic_inc(&spage->ref_count);
1863 }
1864
1865 static void scrub_page_put(struct scrub_page *spage)
1866 {
1867         if (atomic_dec_and_test(&spage->ref_count)) {
1868                 if (spage->page)
1869                         __free_page(spage->page);
1870                 kfree(spage);
1871         }
1872 }
1873
1874 static void scrub_submit(struct scrub_ctx *sctx)
1875 {
1876         struct scrub_bio *sbio;
1877
1878         if (sctx->curr == -1)
1879                 return;
1880
1881         sbio = sctx->bios[sctx->curr];
1882         sctx->curr = -1;
1883         scrub_pending_bio_inc(sctx);
1884
1885         if (!sbio->bio->bi_bdev) {
1886                 /*
1887                  * this case should not happen. If btrfs_map_block() is
1888                  * wrong, it could happen for dev-replace operations on
1889                  * missing devices when no mirrors are available, but in
1890                  * this case it should already fail the mount.
1891                  * This case is handled correctly (but _very_ slowly).
1892                  */
1893                 printk_ratelimited(KERN_WARNING
1894                         "btrfs: scrub_submit(bio bdev == NULL) is unexpected!\n");
1895                 bio_endio(sbio->bio, -EIO);
1896         } else {
1897                 btrfsic_submit_bio(READ, sbio->bio);
1898         }
1899 }
1900
1901 static int scrub_add_page_to_rd_bio(struct scrub_ctx *sctx,
1902                                     struct scrub_page *spage)
1903 {
1904         struct scrub_block *sblock = spage->sblock;
1905         struct scrub_bio *sbio;
1906         int ret;
1907
1908 again:
1909         /*
1910          * grab a fresh bio or wait for one to become available
1911          */
1912         while (sctx->curr == -1) {
1913                 spin_lock(&sctx->list_lock);
1914                 sctx->curr = sctx->first_free;
1915                 if (sctx->curr != -1) {
1916                         sctx->first_free = sctx->bios[sctx->curr]->next_free;
1917                         sctx->bios[sctx->curr]->next_free = -1;
1918                         sctx->bios[sctx->curr]->page_count = 0;
1919                         spin_unlock(&sctx->list_lock);
1920                 } else {
1921                         spin_unlock(&sctx->list_lock);
1922                         wait_event(sctx->list_wait, sctx->first_free != -1);
1923                 }
1924         }
1925         sbio = sctx->bios[sctx->curr];
1926         if (sbio->page_count == 0) {
1927                 struct bio *bio;
1928
1929                 sbio->physical = spage->physical;
1930                 sbio->logical = spage->logical;
1931                 sbio->dev = spage->dev;
1932                 bio = sbio->bio;
1933                 if (!bio) {
1934                         bio = bio_alloc(GFP_NOFS, sctx->pages_per_rd_bio);
1935                         if (!bio)
1936                                 return -ENOMEM;
1937                         sbio->bio = bio;
1938                 }
1939
1940                 bio->bi_private = sbio;
1941                 bio->bi_end_io = scrub_bio_end_io;
1942                 bio->bi_bdev = sbio->dev->bdev;
1943                 bio->bi_sector = sbio->physical >> 9;
1944                 sbio->err = 0;
1945         } else if (sbio->physical + sbio->page_count * PAGE_SIZE !=
1946                    spage->physical ||
1947                    sbio->logical + sbio->page_count * PAGE_SIZE !=
1948                    spage->logical ||
1949                    sbio->dev != spage->dev) {
1950                 scrub_submit(sctx);
1951                 goto again;
1952         }
1953
1954         sbio->pagev[sbio->page_count] = spage;
1955         ret = bio_add_page(sbio->bio, spage->page, PAGE_SIZE, 0);
1956         if (ret != PAGE_SIZE) {
1957                 if (sbio->page_count < 1) {
1958                         bio_put(sbio->bio);
1959                         sbio->bio = NULL;
1960                         return -EIO;
1961                 }
1962                 scrub_submit(sctx);
1963                 goto again;
1964         }
1965
1966         scrub_block_get(sblock); /* one for the page added to the bio */
1967         atomic_inc(&sblock->outstanding_pages);
1968         sbio->page_count++;
1969         if (sbio->page_count == sctx->pages_per_rd_bio)
1970                 scrub_submit(sctx);
1971
1972         return 0;
1973 }
1974
1975 static int scrub_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
1976                        u64 physical, struct btrfs_device *dev, u64 flags,
1977                        u64 gen, int mirror_num, u8 *csum, int force,
1978                        u64 physical_for_dev_replace)
1979 {
1980         struct scrub_block *sblock;
1981         int index;
1982
1983         sblock = kzalloc(sizeof(*sblock), GFP_NOFS);
1984         if (!sblock) {
1985                 spin_lock(&sctx->stat_lock);
1986                 sctx->stat.malloc_errors++;
1987                 spin_unlock(&sctx->stat_lock);
1988                 return -ENOMEM;
1989         }
1990
1991         /* one ref inside this function, plus one for each page added to
1992          * a bio later on */
1993         atomic_set(&sblock->ref_count, 1);
1994         sblock->sctx = sctx;
1995         sblock->no_io_error_seen = 1;
1996
1997         for (index = 0; len > 0; index++) {
1998                 struct scrub_page *spage;
1999                 u64 l = min_t(u64, len, PAGE_SIZE);
2000
2001                 spage = kzalloc(sizeof(*spage), GFP_NOFS);
2002                 if (!spage) {
2003 leave_nomem:
2004                         spin_lock(&sctx->stat_lock);
2005                         sctx->stat.malloc_errors++;
2006                         spin_unlock(&sctx->stat_lock);
2007                         scrub_block_put(sblock);
2008                         return -ENOMEM;
2009                 }
2010                 BUG_ON(index >= SCRUB_MAX_PAGES_PER_BLOCK);
2011                 scrub_page_get(spage);
2012                 sblock->pagev[index] = spage;
2013                 spage->sblock = sblock;
2014                 spage->dev = dev;
2015                 spage->flags = flags;
2016                 spage->generation = gen;
2017                 spage->logical = logical;
2018                 spage->physical = physical;
2019                 spage->physical_for_dev_replace = physical_for_dev_replace;
2020                 spage->mirror_num = mirror_num;
2021                 if (csum) {
2022                         spage->have_csum = 1;
2023                         memcpy(spage->csum, csum, sctx->csum_size);
2024                 } else {
2025                         spage->have_csum = 0;
2026                 }
2027                 sblock->page_count++;
2028                 spage->page = alloc_page(GFP_NOFS);
2029                 if (!spage->page)
2030                         goto leave_nomem;
2031                 len -= l;
2032                 logical += l;
2033                 physical += l;
2034                 physical_for_dev_replace += l;
2035         }
2036
2037         WARN_ON(sblock->page_count == 0);
2038         for (index = 0; index < sblock->page_count; index++) {
2039                 struct scrub_page *spage = sblock->pagev[index];
2040                 int ret;
2041
2042                 ret = scrub_add_page_to_rd_bio(sctx, spage);
2043                 if (ret) {
2044                         scrub_block_put(sblock);
2045                         return ret;
2046                 }
2047         }
2048
2049         if (force)
2050                 scrub_submit(sctx);
2051
2052         /* last one frees, either here or in bio completion for last page */
2053         scrub_block_put(sblock);
2054         return 0;
2055 }
2056
2057 static void scrub_bio_end_io(struct bio *bio, int err)
2058 {
2059         struct scrub_bio *sbio = bio->bi_private;
2060         struct btrfs_fs_info *fs_info = sbio->dev->dev_root->fs_info;
2061
2062         sbio->err = err;
2063         sbio->bio = bio;
2064
2065         btrfs_queue_worker(&fs_info->scrub_workers, &sbio->work);
2066 }
2067
2068 static void scrub_bio_end_io_worker(struct btrfs_work *work)
2069 {
2070         struct scrub_bio *sbio = container_of(work, struct scrub_bio, work);
2071         struct scrub_ctx *sctx = sbio->sctx;
2072         int i;
2073
2074         BUG_ON(sbio->page_count > SCRUB_PAGES_PER_RD_BIO);
2075         if (sbio->err) {
2076                 for (i = 0; i < sbio->page_count; i++) {
2077                         struct scrub_page *spage = sbio->pagev[i];
2078
2079                         spage->io_error = 1;
2080                         spage->sblock->no_io_error_seen = 0;
2081                 }
2082         }
2083
2084         /* now complete the scrub_block items that have all pages completed */
2085         for (i = 0; i < sbio->page_count; i++) {
2086                 struct scrub_page *spage = sbio->pagev[i];
2087                 struct scrub_block *sblock = spage->sblock;
2088
2089                 if (atomic_dec_and_test(&sblock->outstanding_pages))
2090                         scrub_block_complete(sblock);
2091                 scrub_block_put(sblock);
2092         }
2093
2094         bio_put(sbio->bio);
2095         sbio->bio = NULL;
2096         spin_lock(&sctx->list_lock);
2097         sbio->next_free = sctx->first_free;
2098         sctx->first_free = sbio->index;
2099         spin_unlock(&sctx->list_lock);
2100
2101         if (sctx->is_dev_replace &&
2102             atomic_read(&sctx->wr_ctx.flush_all_writes)) {
2103                 mutex_lock(&sctx->wr_ctx.wr_lock);
2104                 scrub_wr_submit(sctx);
2105                 mutex_unlock(&sctx->wr_ctx.wr_lock);
2106         }
2107
2108         scrub_pending_bio_dec(sctx);
2109 }
2110
2111 static void scrub_block_complete(struct scrub_block *sblock)
2112 {
2113         if (!sblock->no_io_error_seen) {
2114                 scrub_handle_errored_block(sblock);
2115         } else {
2116                 /*
2117                  * if has checksum error, write via repair mechanism in
2118                  * dev replace case, otherwise write here in dev replace
2119                  * case.
2120                  */
2121                 if (!scrub_checksum(sblock) && sblock->sctx->is_dev_replace)
2122                         scrub_write_block_to_dev_replace(sblock);
2123         }
2124 }
2125
2126 static int scrub_find_csum(struct scrub_ctx *sctx, u64 logical, u64 len,
2127                            u8 *csum)
2128 {
2129         struct btrfs_ordered_sum *sum = NULL;
2130         int ret = 0;
2131         unsigned long i;
2132         unsigned long num_sectors;
2133
2134         while (!list_empty(&sctx->csum_list)) {
2135                 sum = list_first_entry(&sctx->csum_list,
2136                                        struct btrfs_ordered_sum, list);
2137                 if (sum->bytenr > logical)
2138                         return 0;
2139                 if (sum->bytenr + sum->len > logical)
2140                         break;
2141
2142                 ++sctx->stat.csum_discards;
2143                 list_del(&sum->list);
2144                 kfree(sum);
2145                 sum = NULL;
2146         }
2147         if (!sum)
2148                 return 0;
2149
2150         num_sectors = sum->len / sctx->sectorsize;
2151         for (i = 0; i < num_sectors; ++i) {
2152                 if (sum->sums[i].bytenr == logical) {
2153                         memcpy(csum, &sum->sums[i].sum, sctx->csum_size);
2154                         ret = 1;
2155                         break;
2156                 }
2157         }
2158         if (ret && i == num_sectors - 1) {
2159                 list_del(&sum->list);
2160                 kfree(sum);
2161         }
2162         return ret;
2163 }
2164
2165 /* scrub extent tries to collect up to 64 kB for each bio */
2166 static int scrub_extent(struct scrub_ctx *sctx, u64 logical, u64 len,
2167                         u64 physical, struct btrfs_device *dev, u64 flags,
2168                         u64 gen, int mirror_num, u64 physical_for_dev_replace)
2169 {
2170         int ret;
2171         u8 csum[BTRFS_CSUM_SIZE];
2172         u32 blocksize;
2173
2174         if (flags & BTRFS_EXTENT_FLAG_DATA) {
2175                 blocksize = sctx->sectorsize;
2176                 spin_lock(&sctx->stat_lock);
2177                 sctx->stat.data_extents_scrubbed++;
2178                 sctx->stat.data_bytes_scrubbed += len;
2179                 spin_unlock(&sctx->stat_lock);
2180         } else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
2181                 WARN_ON(sctx->nodesize != sctx->leafsize);
2182                 blocksize = sctx->nodesize;
2183                 spin_lock(&sctx->stat_lock);
2184                 sctx->stat.tree_extents_scrubbed++;
2185                 sctx->stat.tree_bytes_scrubbed += len;
2186                 spin_unlock(&sctx->stat_lock);
2187         } else {
2188                 blocksize = sctx->sectorsize;
2189                 WARN_ON(1);
2190         }
2191
2192         while (len) {
2193                 u64 l = min_t(u64, len, blocksize);
2194                 int have_csum = 0;
2195
2196                 if (flags & BTRFS_EXTENT_FLAG_DATA) {
2197                         /* push csums to sbio */
2198                         have_csum = scrub_find_csum(sctx, logical, l, csum);
2199                         if (have_csum == 0)
2200                                 ++sctx->stat.no_csum;
2201                         if (sctx->is_dev_replace && !have_csum) {
2202                                 ret = copy_nocow_pages(sctx, logical, l,
2203                                                        mirror_num,
2204                                                       physical_for_dev_replace);
2205                                 goto behind_scrub_pages;
2206                         }
2207                 }
2208                 ret = scrub_pages(sctx, logical, l, physical, dev, flags, gen,
2209                                   mirror_num, have_csum ? csum : NULL, 0,
2210                                   physical_for_dev_replace);
2211 behind_scrub_pages:
2212                 if (ret)
2213                         return ret;
2214                 len -= l;
2215                 logical += l;
2216                 physical += l;
2217                 physical_for_dev_replace += l;
2218         }
2219         return 0;
2220 }
2221
2222 static noinline_for_stack int scrub_stripe(struct scrub_ctx *sctx,
2223                                            struct map_lookup *map,
2224                                            struct btrfs_device *scrub_dev,
2225                                            int num, u64 base, u64 length,
2226                                            int is_dev_replace)
2227 {
2228         struct btrfs_path *path;
2229         struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
2230         struct btrfs_root *root = fs_info->extent_root;
2231         struct btrfs_root *csum_root = fs_info->csum_root;
2232         struct btrfs_extent_item *extent;
2233         struct blk_plug plug;
2234         u64 flags;
2235         int ret;
2236         int slot;
2237         int i;
2238         u64 nstripes;
2239         struct extent_buffer *l;
2240         struct btrfs_key key;
2241         u64 physical;
2242         u64 logical;
2243         u64 generation;
2244         int mirror_num;
2245         struct reada_control *reada1;
2246         struct reada_control *reada2;
2247         struct btrfs_key key_start;
2248         struct btrfs_key key_end;
2249         u64 increment = map->stripe_len;
2250         u64 offset;
2251         u64 extent_logical;
2252         u64 extent_physical;
2253         u64 extent_len;
2254         struct btrfs_device *extent_dev;
2255         int extent_mirror_num;
2256
2257         nstripes = length;
2258         offset = 0;
2259         do_div(nstripes, map->stripe_len);
2260         if (map->type & BTRFS_BLOCK_GROUP_RAID0) {
2261                 offset = map->stripe_len * num;
2262                 increment = map->stripe_len * map->num_stripes;
2263                 mirror_num = 1;
2264         } else if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
2265                 int factor = map->num_stripes / map->sub_stripes;
2266                 offset = map->stripe_len * (num / map->sub_stripes);
2267                 increment = map->stripe_len * factor;
2268                 mirror_num = num % map->sub_stripes + 1;
2269         } else if (map->type & BTRFS_BLOCK_GROUP_RAID1) {
2270                 increment = map->stripe_len;
2271                 mirror_num = num % map->num_stripes + 1;
2272         } else if (map->type & BTRFS_BLOCK_GROUP_DUP) {
2273                 increment = map->stripe_len;
2274                 mirror_num = num % map->num_stripes + 1;
2275         } else {
2276                 increment = map->stripe_len;
2277                 mirror_num = 1;
2278         }
2279
2280         path = btrfs_alloc_path();
2281         if (!path)
2282                 return -ENOMEM;
2283
2284         /*
2285          * work on commit root. The related disk blocks are static as
2286          * long as COW is applied. This means, it is save to rewrite
2287          * them to repair disk errors without any race conditions
2288          */
2289         path->search_commit_root = 1;
2290         path->skip_locking = 1;
2291
2292         /*
2293          * trigger the readahead for extent tree csum tree and wait for
2294          * completion. During readahead, the scrub is officially paused
2295          * to not hold off transaction commits
2296          */
2297         logical = base + offset;
2298
2299         wait_event(sctx->list_wait,
2300                    atomic_read(&sctx->bios_in_flight) == 0);
2301         atomic_inc(&fs_info->scrubs_paused);
2302         wake_up(&fs_info->scrub_pause_wait);
2303
2304         /* FIXME it might be better to start readahead at commit root */
2305         key_start.objectid = logical;
2306         key_start.type = BTRFS_EXTENT_ITEM_KEY;
2307         key_start.offset = (u64)0;
2308         key_end.objectid = base + offset + nstripes * increment;
2309         key_end.type = BTRFS_EXTENT_ITEM_KEY;
2310         key_end.offset = (u64)0;
2311         reada1 = btrfs_reada_add(root, &key_start, &key_end);
2312
2313         key_start.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
2314         key_start.type = BTRFS_EXTENT_CSUM_KEY;
2315         key_start.offset = logical;
2316         key_end.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
2317         key_end.type = BTRFS_EXTENT_CSUM_KEY;
2318         key_end.offset = base + offset + nstripes * increment;
2319         reada2 = btrfs_reada_add(csum_root, &key_start, &key_end);
2320
2321         if (!IS_ERR(reada1))
2322                 btrfs_reada_wait(reada1);
2323         if (!IS_ERR(reada2))
2324                 btrfs_reada_wait(reada2);
2325
2326         mutex_lock(&fs_info->scrub_lock);
2327         while (atomic_read(&fs_info->scrub_pause_req)) {
2328                 mutex_unlock(&fs_info->scrub_lock);
2329                 wait_event(fs_info->scrub_pause_wait,
2330                    atomic_read(&fs_info->scrub_pause_req) == 0);
2331                 mutex_lock(&fs_info->scrub_lock);
2332         }
2333         atomic_dec(&fs_info->scrubs_paused);
2334         mutex_unlock(&fs_info->scrub_lock);
2335         wake_up(&fs_info->scrub_pause_wait);
2336
2337         /*
2338          * collect all data csums for the stripe to avoid seeking during
2339          * the scrub. This might currently (crc32) end up to be about 1MB
2340          */
2341         blk_start_plug(&plug);
2342
2343         /*
2344          * now find all extents for each stripe and scrub them
2345          */
2346         logical = base + offset;
2347         physical = map->stripes[num].physical;
2348         ret = 0;
2349         for (i = 0; i < nstripes; ++i) {
2350                 /*
2351                  * canceled?
2352                  */
2353                 if (atomic_read(&fs_info->scrub_cancel_req) ||
2354                     atomic_read(&sctx->cancel_req)) {
2355                         ret = -ECANCELED;
2356                         goto out;
2357                 }
2358                 /*
2359                  * check to see if we have to pause
2360                  */
2361                 if (atomic_read(&fs_info->scrub_pause_req)) {
2362                         /* push queued extents */
2363                         atomic_set(&sctx->wr_ctx.flush_all_writes, 1);
2364                         scrub_submit(sctx);
2365                         mutex_lock(&sctx->wr_ctx.wr_lock);
2366                         scrub_wr_submit(sctx);
2367                         mutex_unlock(&sctx->wr_ctx.wr_lock);
2368                         wait_event(sctx->list_wait,
2369                                    atomic_read(&sctx->bios_in_flight) == 0);
2370                         atomic_set(&sctx->wr_ctx.flush_all_writes, 0);
2371                         atomic_inc(&fs_info->scrubs_paused);
2372                         wake_up(&fs_info->scrub_pause_wait);
2373                         mutex_lock(&fs_info->scrub_lock);
2374                         while (atomic_read(&fs_info->scrub_pause_req)) {
2375                                 mutex_unlock(&fs_info->scrub_lock);
2376                                 wait_event(fs_info->scrub_pause_wait,
2377                                    atomic_read(&fs_info->scrub_pause_req) == 0);
2378                                 mutex_lock(&fs_info->scrub_lock);
2379                         }
2380                         atomic_dec(&fs_info->scrubs_paused);
2381                         mutex_unlock(&fs_info->scrub_lock);
2382                         wake_up(&fs_info->scrub_pause_wait);
2383                 }
2384
2385                 ret = btrfs_lookup_csums_range(csum_root, logical,
2386                                                logical + map->stripe_len - 1,
2387                                                &sctx->csum_list, 1);
2388                 if (ret)
2389                         goto out;
2390
2391                 key.objectid = logical;
2392                 key.type = BTRFS_EXTENT_ITEM_KEY;
2393                 key.offset = (u64)0;
2394
2395                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
2396                 if (ret < 0)
2397                         goto out;
2398                 if (ret > 0) {
2399                         ret = btrfs_previous_item(root, path, 0,
2400                                                   BTRFS_EXTENT_ITEM_KEY);
2401                         if (ret < 0)
2402                                 goto out;
2403                         if (ret > 0) {
2404                                 /* there's no smaller item, so stick with the
2405                                  * larger one */
2406                                 btrfs_release_path(path);
2407                                 ret = btrfs_search_slot(NULL, root, &key,
2408                                                         path, 0, 0);
2409                                 if (ret < 0)
2410                                         goto out;
2411                         }
2412                 }
2413
2414                 while (1) {
2415                         l = path->nodes[0];
2416                         slot = path->slots[0];
2417                         if (slot >= btrfs_header_nritems(l)) {
2418                                 ret = btrfs_next_leaf(root, path);
2419                                 if (ret == 0)
2420                                         continue;
2421                                 if (ret < 0)
2422                                         goto out;
2423
2424                                 break;
2425                         }
2426                         btrfs_item_key_to_cpu(l, &key, slot);
2427
2428                         if (key.objectid + key.offset <= logical)
2429                                 goto next;
2430
2431                         if (key.objectid >= logical + map->stripe_len)
2432                                 break;
2433
2434                         if (btrfs_key_type(&key) != BTRFS_EXTENT_ITEM_KEY)
2435                                 goto next;
2436
2437                         extent = btrfs_item_ptr(l, slot,
2438                                                 struct btrfs_extent_item);
2439                         flags = btrfs_extent_flags(l, extent);
2440                         generation = btrfs_extent_generation(l, extent);
2441
2442                         if (key.objectid < logical &&
2443                             (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)) {
2444                                 printk(KERN_ERR
2445                                        "btrfs scrub: tree block %llu spanning "
2446                                        "stripes, ignored. logical=%llu\n",
2447                                        (unsigned long long)key.objectid,
2448                                        (unsigned long long)logical);
2449                                 goto next;
2450                         }
2451
2452                         /*
2453                          * trim extent to this stripe
2454                          */
2455                         if (key.objectid < logical) {
2456                                 key.offset -= logical - key.objectid;
2457                                 key.objectid = logical;
2458                         }
2459                         if (key.objectid + key.offset >
2460                             logical + map->stripe_len) {
2461                                 key.offset = logical + map->stripe_len -
2462                                              key.objectid;
2463                         }
2464
2465                         extent_logical = key.objectid;
2466                         extent_physical = key.objectid - logical + physical;
2467                         extent_len = key.offset;
2468                         extent_dev = scrub_dev;
2469                         extent_mirror_num = mirror_num;
2470                         if (is_dev_replace)
2471                                 scrub_remap_extent(fs_info, extent_logical,
2472                                                    extent_len, &extent_physical,
2473                                                    &extent_dev,
2474                                                    &extent_mirror_num);
2475                         ret = scrub_extent(sctx, extent_logical, extent_len,
2476                                            extent_physical, extent_dev, flags,
2477                                            generation, extent_mirror_num,
2478                                            key.objectid - logical + physical);
2479                         if (ret)
2480                                 goto out;
2481
2482 next:
2483                         path->slots[0]++;
2484                 }
2485                 btrfs_release_path(path);
2486                 logical += increment;
2487                 physical += map->stripe_len;
2488                 spin_lock(&sctx->stat_lock);
2489                 sctx->stat.last_physical = physical;
2490                 spin_unlock(&sctx->stat_lock);
2491         }
2492 out:
2493         /* push queued extents */
2494         scrub_submit(sctx);
2495         mutex_lock(&sctx->wr_ctx.wr_lock);
2496         scrub_wr_submit(sctx);
2497         mutex_unlock(&sctx->wr_ctx.wr_lock);
2498
2499         blk_finish_plug(&plug);
2500         btrfs_free_path(path);
2501         return ret < 0 ? ret : 0;
2502 }
2503
2504 static noinline_for_stack int scrub_chunk(struct scrub_ctx *sctx,
2505                                           struct btrfs_device *scrub_dev,
2506                                           u64 chunk_tree, u64 chunk_objectid,
2507                                           u64 chunk_offset, u64 length,
2508                                           u64 dev_offset, int is_dev_replace)
2509 {
2510         struct btrfs_mapping_tree *map_tree =
2511                 &sctx->dev_root->fs_info->mapping_tree;
2512         struct map_lookup *map;
2513         struct extent_map *em;
2514         int i;
2515         int ret = 0;
2516
2517         read_lock(&map_tree->map_tree.lock);
2518         em = lookup_extent_mapping(&map_tree->map_tree, chunk_offset, 1);
2519         read_unlock(&map_tree->map_tree.lock);
2520
2521         if (!em)
2522                 return -EINVAL;
2523
2524         map = (struct map_lookup *)em->bdev;
2525         if (em->start != chunk_offset)
2526                 goto out;
2527
2528         if (em->len < length)
2529                 goto out;
2530
2531         for (i = 0; i < map->num_stripes; ++i) {
2532                 if (map->stripes[i].dev->bdev == scrub_dev->bdev &&
2533                     map->stripes[i].physical == dev_offset) {
2534                         ret = scrub_stripe(sctx, map, scrub_dev, i,
2535                                            chunk_offset, length,
2536                                            is_dev_replace);
2537                         if (ret)
2538                                 goto out;
2539                 }
2540         }
2541 out:
2542         free_extent_map(em);
2543
2544         return ret;
2545 }
2546
2547 static noinline_for_stack
2548 int scrub_enumerate_chunks(struct scrub_ctx *sctx,
2549                            struct btrfs_device *scrub_dev, u64 start, u64 end,
2550                            int is_dev_replace)
2551 {
2552         struct btrfs_dev_extent *dev_extent = NULL;
2553         struct btrfs_path *path;
2554         struct btrfs_root *root = sctx->dev_root;
2555         struct btrfs_fs_info *fs_info = root->fs_info;
2556         u64 length;
2557         u64 chunk_tree;
2558         u64 chunk_objectid;
2559         u64 chunk_offset;
2560         int ret;
2561         int slot;
2562         struct extent_buffer *l;
2563         struct btrfs_key key;
2564         struct btrfs_key found_key;
2565         struct btrfs_block_group_cache *cache;
2566         struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
2567
2568         path = btrfs_alloc_path();
2569         if (!path)
2570                 return -ENOMEM;
2571
2572         path->reada = 2;
2573         path->search_commit_root = 1;
2574         path->skip_locking = 1;
2575
2576         key.objectid = scrub_dev->devid;
2577         key.offset = 0ull;
2578         key.type = BTRFS_DEV_EXTENT_KEY;
2579
2580         while (1) {
2581                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
2582                 if (ret < 0)
2583                         break;
2584                 if (ret > 0) {
2585                         if (path->slots[0] >=
2586                             btrfs_header_nritems(path->nodes[0])) {
2587                                 ret = btrfs_next_leaf(root, path);
2588                                 if (ret)
2589                                         break;
2590                         }
2591                 }
2592
2593                 l = path->nodes[0];
2594                 slot = path->slots[0];
2595
2596                 btrfs_item_key_to_cpu(l, &found_key, slot);
2597
2598                 if (found_key.objectid != scrub_dev->devid)
2599                         break;
2600
2601                 if (btrfs_key_type(&found_key) != BTRFS_DEV_EXTENT_KEY)
2602                         break;
2603
2604                 if (found_key.offset >= end)
2605                         break;
2606
2607                 if (found_key.offset < key.offset)
2608                         break;
2609
2610                 dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent);
2611                 length = btrfs_dev_extent_length(l, dev_extent);
2612
2613                 if (found_key.offset + length <= start) {
2614                         key.offset = found_key.offset + length;
2615                         btrfs_release_path(path);
2616                         continue;
2617                 }
2618
2619                 chunk_tree = btrfs_dev_extent_chunk_tree(l, dev_extent);
2620                 chunk_objectid = btrfs_dev_extent_chunk_objectid(l, dev_extent);
2621                 chunk_offset = btrfs_dev_extent_chunk_offset(l, dev_extent);
2622
2623                 /*
2624                  * get a reference on the corresponding block group to prevent
2625                  * the chunk from going away while we scrub it
2626                  */
2627                 cache = btrfs_lookup_block_group(fs_info, chunk_offset);
2628                 if (!cache) {
2629                         ret = -ENOENT;
2630                         break;
2631                 }
2632                 dev_replace->cursor_right = found_key.offset + length;
2633                 dev_replace->cursor_left = found_key.offset;
2634                 dev_replace->item_needs_writeback = 1;
2635                 ret = scrub_chunk(sctx, scrub_dev, chunk_tree, chunk_objectid,
2636                                   chunk_offset, length, found_key.offset,
2637                                   is_dev_replace);
2638
2639                 /*
2640                  * flush, submit all pending read and write bios, afterwards
2641                  * wait for them.
2642                  * Note that in the dev replace case, a read request causes
2643                  * write requests that are submitted in the read completion
2644                  * worker. Therefore in the current situation, it is required
2645                  * that all write requests are flushed, so that all read and
2646                  * write requests are really completed when bios_in_flight
2647                  * changes to 0.
2648                  */
2649                 atomic_set(&sctx->wr_ctx.flush_all_writes, 1);
2650                 scrub_submit(sctx);
2651                 mutex_lock(&sctx->wr_ctx.wr_lock);
2652                 scrub_wr_submit(sctx);
2653                 mutex_unlock(&sctx->wr_ctx.wr_lock);
2654
2655                 wait_event(sctx->list_wait,
2656                            atomic_read(&sctx->bios_in_flight) == 0);
2657                 atomic_set(&sctx->wr_ctx.flush_all_writes, 0);
2658                 atomic_inc(&fs_info->scrubs_paused);
2659                 wake_up(&fs_info->scrub_pause_wait);
2660                 wait_event(sctx->list_wait,
2661                            atomic_read(&sctx->workers_pending) == 0);
2662
2663                 mutex_lock(&fs_info->scrub_lock);
2664                 while (atomic_read(&fs_info->scrub_pause_req)) {
2665                         mutex_unlock(&fs_info->scrub_lock);
2666                         wait_event(fs_info->scrub_pause_wait,
2667                            atomic_read(&fs_info->scrub_pause_req) == 0);
2668                         mutex_lock(&fs_info->scrub_lock);
2669                 }
2670                 atomic_dec(&fs_info->scrubs_paused);
2671                 mutex_unlock(&fs_info->scrub_lock);
2672                 wake_up(&fs_info->scrub_pause_wait);
2673
2674                 dev_replace->cursor_left = dev_replace->cursor_right;
2675                 dev_replace->item_needs_writeback = 1;
2676                 btrfs_put_block_group(cache);
2677                 if (ret)
2678                         break;
2679                 if (is_dev_replace &&
2680                     atomic64_read(&dev_replace->num_write_errors) > 0) {
2681                         ret = -EIO;
2682                         break;
2683                 }
2684                 if (sctx->stat.malloc_errors > 0) {
2685                         ret = -ENOMEM;
2686                         break;
2687                 }
2688
2689                 key.offset = found_key.offset + length;
2690                 btrfs_release_path(path);
2691         }
2692
2693         btrfs_free_path(path);
2694
2695         /*
2696          * ret can still be 1 from search_slot or next_leaf,
2697          * that's not an error
2698          */
2699         return ret < 0 ? ret : 0;
2700 }
2701
2702 static noinline_for_stack int scrub_supers(struct scrub_ctx *sctx,
2703                                            struct btrfs_device *scrub_dev)
2704 {
2705         int     i;
2706         u64     bytenr;
2707         u64     gen;
2708         int     ret;
2709         struct btrfs_root *root = sctx->dev_root;
2710
2711         if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR)
2712                 return -EIO;
2713
2714         gen = root->fs_info->last_trans_committed;
2715
2716         for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
2717                 bytenr = btrfs_sb_offset(i);
2718                 if (bytenr + BTRFS_SUPER_INFO_SIZE > scrub_dev->total_bytes)
2719                         break;
2720
2721                 ret = scrub_pages(sctx, bytenr, BTRFS_SUPER_INFO_SIZE, bytenr,
2722                                   scrub_dev, BTRFS_EXTENT_FLAG_SUPER, gen, i,
2723                                   NULL, 1, bytenr);
2724                 if (ret)
2725                         return ret;
2726         }
2727         wait_event(sctx->list_wait, atomic_read(&sctx->bios_in_flight) == 0);
2728
2729         return 0;
2730 }
2731
2732 /*
2733  * get a reference count on fs_info->scrub_workers. start worker if necessary
2734  */
2735 static noinline_for_stack int scrub_workers_get(struct btrfs_fs_info *fs_info,
2736                                                 int is_dev_replace)
2737 {
2738         int ret = 0;
2739
2740         mutex_lock(&fs_info->scrub_lock);
2741         if (fs_info->scrub_workers_refcnt == 0) {
2742                 if (is_dev_replace)
2743                         btrfs_init_workers(&fs_info->scrub_workers, "scrub", 1,
2744                                         &fs_info->generic_worker);
2745                 else
2746                         btrfs_init_workers(&fs_info->scrub_workers, "scrub",
2747                                         fs_info->thread_pool_size,
2748                                         &fs_info->generic_worker);
2749                 fs_info->scrub_workers.idle_thresh = 4;
2750                 ret = btrfs_start_workers(&fs_info->scrub_workers);
2751                 if (ret)
2752                         goto out;
2753                 btrfs_init_workers(&fs_info->scrub_wr_completion_workers,
2754                                    "scrubwrc",
2755                                    fs_info->thread_pool_size,
2756                                    &fs_info->generic_worker);
2757                 fs_info->scrub_wr_completion_workers.idle_thresh = 2;
2758                 ret = btrfs_start_workers(
2759                                 &fs_info->scrub_wr_completion_workers);
2760                 if (ret)
2761                         goto out;
2762                 btrfs_init_workers(&fs_info->scrub_nocow_workers, "scrubnc", 1,
2763                                    &fs_info->generic_worker);
2764                 ret = btrfs_start_workers(&fs_info->scrub_nocow_workers);
2765                 if (ret)
2766                         goto out;
2767         }
2768         ++fs_info->scrub_workers_refcnt;
2769 out:
2770         mutex_unlock(&fs_info->scrub_lock);
2771
2772         return ret;
2773 }
2774
2775 static noinline_for_stack void scrub_workers_put(struct btrfs_fs_info *fs_info)
2776 {
2777         mutex_lock(&fs_info->scrub_lock);
2778         if (--fs_info->scrub_workers_refcnt == 0) {
2779                 btrfs_stop_workers(&fs_info->scrub_workers);
2780                 btrfs_stop_workers(&fs_info->scrub_wr_completion_workers);
2781                 btrfs_stop_workers(&fs_info->scrub_nocow_workers);
2782         }
2783         WARN_ON(fs_info->scrub_workers_refcnt < 0);
2784         mutex_unlock(&fs_info->scrub_lock);
2785 }
2786
2787 int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start,
2788                     u64 end, struct btrfs_scrub_progress *progress,
2789                     int readonly, int is_dev_replace)
2790 {
2791         struct scrub_ctx *sctx;
2792         int ret;
2793         struct btrfs_device *dev;
2794
2795         if (btrfs_fs_closing(fs_info))
2796                 return -EINVAL;
2797
2798         /*
2799          * check some assumptions
2800          */
2801         if (fs_info->chunk_root->nodesize != fs_info->chunk_root->leafsize) {
2802                 printk(KERN_ERR
2803                        "btrfs_scrub: size assumption nodesize == leafsize (%d == %d) fails\n",
2804                        fs_info->chunk_root->nodesize,
2805                        fs_info->chunk_root->leafsize);
2806                 return -EINVAL;
2807         }
2808
2809         if (fs_info->chunk_root->nodesize > BTRFS_STRIPE_LEN) {
2810                 /*
2811                  * in this case scrub is unable to calculate the checksum
2812                  * the way scrub is implemented. Do not handle this
2813                  * situation at all because it won't ever happen.
2814                  */
2815                 printk(KERN_ERR
2816                        "btrfs_scrub: size assumption nodesize <= BTRFS_STRIPE_LEN (%d <= %d) fails\n",
2817                        fs_info->chunk_root->nodesize, BTRFS_STRIPE_LEN);
2818                 return -EINVAL;
2819         }
2820
2821         if (fs_info->chunk_root->sectorsize != PAGE_SIZE) {
2822                 /* not supported for data w/o checksums */
2823                 printk(KERN_ERR
2824                        "btrfs_scrub: size assumption sectorsize != PAGE_SIZE (%d != %lld) fails\n",
2825                        fs_info->chunk_root->sectorsize,
2826                        (unsigned long long)PAGE_SIZE);
2827                 return -EINVAL;
2828         }
2829
2830         if (fs_info->chunk_root->nodesize >
2831             PAGE_SIZE * SCRUB_MAX_PAGES_PER_BLOCK ||
2832             fs_info->chunk_root->sectorsize >
2833             PAGE_SIZE * SCRUB_MAX_PAGES_PER_BLOCK) {
2834                 /*
2835                  * would exhaust the array bounds of pagev member in
2836                  * struct scrub_block
2837                  */
2838                 pr_err("btrfs_scrub: size assumption nodesize and sectorsize <= SCRUB_MAX_PAGES_PER_BLOCK (%d <= %d && %d <= %d) fails\n",
2839                        fs_info->chunk_root->nodesize,
2840                        SCRUB_MAX_PAGES_PER_BLOCK,
2841                        fs_info->chunk_root->sectorsize,
2842                        SCRUB_MAX_PAGES_PER_BLOCK);
2843                 return -EINVAL;
2844         }
2845
2846         ret = scrub_workers_get(fs_info, is_dev_replace);
2847         if (ret)
2848                 return ret;
2849
2850         mutex_lock(&fs_info->fs_devices->device_list_mutex);
2851         dev = btrfs_find_device(fs_info, devid, NULL, NULL);
2852         if (!dev || (dev->missing && !is_dev_replace)) {
2853                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
2854                 scrub_workers_put(fs_info);
2855                 return -ENODEV;
2856         }
2857         mutex_lock(&fs_info->scrub_lock);
2858
2859         if (!dev->in_fs_metadata || dev->is_tgtdev_for_dev_replace) {
2860                 mutex_unlock(&fs_info->scrub_lock);
2861                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
2862                 scrub_workers_put(fs_info);
2863                 return -EIO;
2864         }
2865
2866         btrfs_dev_replace_lock(&fs_info->dev_replace);
2867         if (dev->scrub_device ||
2868             (!is_dev_replace &&
2869              btrfs_dev_replace_is_ongoing(&fs_info->dev_replace))) {
2870                 btrfs_dev_replace_unlock(&fs_info->dev_replace);
2871                 mutex_unlock(&fs_info->scrub_lock);
2872                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
2873                 scrub_workers_put(fs_info);
2874                 return -EINPROGRESS;
2875         }
2876         btrfs_dev_replace_unlock(&fs_info->dev_replace);
2877         sctx = scrub_setup_ctx(dev, is_dev_replace);
2878         if (IS_ERR(sctx)) {
2879                 mutex_unlock(&fs_info->scrub_lock);
2880                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
2881                 scrub_workers_put(fs_info);
2882                 return PTR_ERR(sctx);
2883         }
2884         sctx->readonly = readonly;
2885         dev->scrub_device = sctx;
2886
2887         atomic_inc(&fs_info->scrubs_running);
2888         mutex_unlock(&fs_info->scrub_lock);
2889         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
2890
2891         if (!is_dev_replace) {
2892                 down_read(&fs_info->scrub_super_lock);
2893                 ret = scrub_supers(sctx, dev);
2894                 up_read(&fs_info->scrub_super_lock);
2895         }
2896
2897         if (!ret)
2898                 ret = scrub_enumerate_chunks(sctx, dev, start, end,
2899                                              is_dev_replace);
2900
2901         wait_event(sctx->list_wait, atomic_read(&sctx->bios_in_flight) == 0);
2902         atomic_dec(&fs_info->scrubs_running);
2903         wake_up(&fs_info->scrub_pause_wait);
2904
2905         wait_event(sctx->list_wait, atomic_read(&sctx->workers_pending) == 0);
2906
2907         if (progress)
2908                 memcpy(progress, &sctx->stat, sizeof(*progress));
2909
2910         mutex_lock(&fs_info->scrub_lock);
2911         dev->scrub_device = NULL;
2912         mutex_unlock(&fs_info->scrub_lock);
2913
2914         scrub_free_ctx(sctx);
2915         scrub_workers_put(fs_info);
2916
2917         return ret;
2918 }
2919
2920 void btrfs_scrub_pause(struct btrfs_root *root)
2921 {
2922         struct btrfs_fs_info *fs_info = root->fs_info;
2923
2924         mutex_lock(&fs_info->scrub_lock);
2925         atomic_inc(&fs_info->scrub_pause_req);
2926         while (atomic_read(&fs_info->scrubs_paused) !=
2927                atomic_read(&fs_info->scrubs_running)) {
2928                 mutex_unlock(&fs_info->scrub_lock);
2929                 wait_event(fs_info->scrub_pause_wait,
2930                            atomic_read(&fs_info->scrubs_paused) ==
2931                            atomic_read(&fs_info->scrubs_running));
2932                 mutex_lock(&fs_info->scrub_lock);
2933         }
2934         mutex_unlock(&fs_info->scrub_lock);
2935 }
2936
2937 void btrfs_scrub_continue(struct btrfs_root *root)
2938 {
2939         struct btrfs_fs_info *fs_info = root->fs_info;
2940
2941         atomic_dec(&fs_info->scrub_pause_req);
2942         wake_up(&fs_info->scrub_pause_wait);
2943 }
2944
2945 void btrfs_scrub_pause_super(struct btrfs_root *root)
2946 {
2947         down_write(&root->fs_info->scrub_super_lock);
2948 }
2949
2950 void btrfs_scrub_continue_super(struct btrfs_root *root)
2951 {
2952         up_write(&root->fs_info->scrub_super_lock);
2953 }
2954
2955 int btrfs_scrub_cancel(struct btrfs_fs_info *fs_info)
2956 {
2957         mutex_lock(&fs_info->scrub_lock);
2958         if (!atomic_read(&fs_info->scrubs_running)) {
2959                 mutex_unlock(&fs_info->scrub_lock);
2960                 return -ENOTCONN;
2961         }
2962
2963         atomic_inc(&fs_info->scrub_cancel_req);
2964         while (atomic_read(&fs_info->scrubs_running)) {
2965                 mutex_unlock(&fs_info->scrub_lock);
2966                 wait_event(fs_info->scrub_pause_wait,
2967                            atomic_read(&fs_info->scrubs_running) == 0);
2968                 mutex_lock(&fs_info->scrub_lock);
2969         }
2970         atomic_dec(&fs_info->scrub_cancel_req);
2971         mutex_unlock(&fs_info->scrub_lock);
2972
2973         return 0;
2974 }
2975
2976 int btrfs_scrub_cancel_dev(struct btrfs_fs_info *fs_info,
2977                            struct btrfs_device *dev)
2978 {
2979         struct scrub_ctx *sctx;
2980
2981         mutex_lock(&fs_info->scrub_lock);
2982         sctx = dev->scrub_device;
2983         if (!sctx) {
2984                 mutex_unlock(&fs_info->scrub_lock);
2985                 return -ENOTCONN;
2986         }
2987         atomic_inc(&sctx->cancel_req);
2988         while (dev->scrub_device) {
2989                 mutex_unlock(&fs_info->scrub_lock);
2990                 wait_event(fs_info->scrub_pause_wait,
2991                            dev->scrub_device == NULL);
2992                 mutex_lock(&fs_info->scrub_lock);
2993         }
2994         mutex_unlock(&fs_info->scrub_lock);
2995
2996         return 0;
2997 }
2998
2999 int btrfs_scrub_cancel_devid(struct btrfs_root *root, u64 devid)
3000 {
3001         struct btrfs_fs_info *fs_info = root->fs_info;
3002         struct btrfs_device *dev;
3003         int ret;
3004
3005         /*
3006          * we have to hold the device_list_mutex here so the device
3007          * does not go away in cancel_dev. FIXME: find a better solution
3008          */
3009         mutex_lock(&fs_info->fs_devices->device_list_mutex);
3010         dev = btrfs_find_device(fs_info, devid, NULL, NULL);
3011         if (!dev) {
3012                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3013                 return -ENODEV;
3014         }
3015         ret = btrfs_scrub_cancel_dev(fs_info, dev);
3016         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
3017
3018         return ret;
3019 }
3020
3021 int btrfs_scrub_progress(struct btrfs_root *root, u64 devid,
3022                          struct btrfs_scrub_progress *progress)
3023 {
3024         struct btrfs_device *dev;
3025         struct scrub_ctx *sctx = NULL;
3026
3027         mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
3028         dev = btrfs_find_device(root->fs_info, devid, NULL, NULL);
3029         if (dev)
3030                 sctx = dev->scrub_device;
3031         if (sctx)
3032                 memcpy(progress, &sctx->stat, sizeof(*progress));
3033         mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
3034
3035         return dev ? (sctx ? 0 : -ENOTCONN) : -ENODEV;
3036 }
3037
3038 static void scrub_remap_extent(struct btrfs_fs_info *fs_info,
3039                                u64 extent_logical, u64 extent_len,
3040                                u64 *extent_physical,
3041                                struct btrfs_device **extent_dev,
3042                                int *extent_mirror_num)
3043 {
3044         u64 mapped_length;
3045         struct btrfs_bio *bbio = NULL;
3046         int ret;
3047
3048         mapped_length = extent_len;
3049         ret = btrfs_map_block(fs_info, READ, extent_logical,
3050                               &mapped_length, &bbio, 0);
3051         if (ret || !bbio || mapped_length < extent_len ||
3052             !bbio->stripes[0].dev->bdev) {
3053                 kfree(bbio);
3054                 return;
3055         }
3056
3057         *extent_physical = bbio->stripes[0].physical;
3058         *extent_mirror_num = bbio->mirror_num;
3059         *extent_dev = bbio->stripes[0].dev;
3060         kfree(bbio);
3061 }
3062
3063 static int scrub_setup_wr_ctx(struct scrub_ctx *sctx,
3064                               struct scrub_wr_ctx *wr_ctx,
3065                               struct btrfs_fs_info *fs_info,
3066                               struct btrfs_device *dev,
3067                               int is_dev_replace)
3068 {
3069         WARN_ON(wr_ctx->wr_curr_bio != NULL);
3070
3071         mutex_init(&wr_ctx->wr_lock);
3072         wr_ctx->wr_curr_bio = NULL;
3073         if (!is_dev_replace)
3074                 return 0;
3075
3076         WARN_ON(!dev->bdev);
3077         wr_ctx->pages_per_wr_bio = min_t(int, SCRUB_PAGES_PER_WR_BIO,
3078                                          bio_get_nr_vecs(dev->bdev));
3079         wr_ctx->tgtdev = dev;
3080         atomic_set(&wr_ctx->flush_all_writes, 0);
3081         return 0;
3082 }
3083
3084 static void scrub_free_wr_ctx(struct scrub_wr_ctx *wr_ctx)
3085 {
3086         mutex_lock(&wr_ctx->wr_lock);
3087         kfree(wr_ctx->wr_curr_bio);
3088         wr_ctx->wr_curr_bio = NULL;
3089         mutex_unlock(&wr_ctx->wr_lock);
3090 }
3091
3092 static int copy_nocow_pages(struct scrub_ctx *sctx, u64 logical, u64 len,
3093                             int mirror_num, u64 physical_for_dev_replace)
3094 {
3095         struct scrub_copy_nocow_ctx *nocow_ctx;
3096         struct btrfs_fs_info *fs_info = sctx->dev_root->fs_info;
3097
3098         nocow_ctx = kzalloc(sizeof(*nocow_ctx), GFP_NOFS);
3099         if (!nocow_ctx) {
3100                 spin_lock(&sctx->stat_lock);
3101                 sctx->stat.malloc_errors++;
3102                 spin_unlock(&sctx->stat_lock);
3103                 return -ENOMEM;
3104         }
3105
3106         scrub_pending_trans_workers_inc(sctx);
3107
3108         nocow_ctx->sctx = sctx;
3109         nocow_ctx->logical = logical;
3110         nocow_ctx->len = len;
3111         nocow_ctx->mirror_num = mirror_num;
3112         nocow_ctx->physical_for_dev_replace = physical_for_dev_replace;
3113         nocow_ctx->work.func = copy_nocow_pages_worker;
3114         btrfs_queue_worker(&fs_info->scrub_nocow_workers,
3115                            &nocow_ctx->work);
3116
3117         return 0;
3118 }
3119
3120 static void copy_nocow_pages_worker(struct btrfs_work *work)
3121 {
3122         struct scrub_copy_nocow_ctx *nocow_ctx =
3123                 container_of(work, struct scrub_copy_nocow_ctx, work);
3124         struct scrub_ctx *sctx = nocow_ctx->sctx;
3125         u64 logical = nocow_ctx->logical;
3126         u64 len = nocow_ctx->len;
3127         int mirror_num = nocow_ctx->mirror_num;
3128         u64 physical_for_dev_replace = nocow_ctx->physical_for_dev_replace;
3129         int ret;
3130         struct btrfs_trans_handle *trans = NULL;
3131         struct btrfs_fs_info *fs_info;
3132         struct btrfs_path *path;
3133         struct btrfs_root *root;
3134         int not_written = 0;
3135
3136         fs_info = sctx->dev_root->fs_info;
3137         root = fs_info->extent_root;
3138
3139         path = btrfs_alloc_path();
3140         if (!path) {
3141                 spin_lock(&sctx->stat_lock);
3142                 sctx->stat.malloc_errors++;
3143                 spin_unlock(&sctx->stat_lock);
3144                 not_written = 1;
3145                 goto out;
3146         }
3147
3148         trans = btrfs_join_transaction(root);
3149         if (IS_ERR(trans)) {
3150                 not_written = 1;
3151                 goto out;
3152         }
3153
3154         ret = iterate_inodes_from_logical(logical, fs_info, path,
3155                                           copy_nocow_pages_for_inode,
3156                                           nocow_ctx);
3157         if (ret != 0 && ret != -ENOENT) {
3158                 pr_warn("iterate_inodes_from_logical() failed: log %llu, phys %llu, len %llu, mir %llu, ret %d\n",
3159                         (unsigned long long)logical,
3160                         (unsigned long long)physical_for_dev_replace,
3161                         (unsigned long long)len,
3162                         (unsigned long long)mirror_num, ret);
3163                 not_written = 1;
3164                 goto out;
3165         }
3166
3167 out:
3168         if (trans && !IS_ERR(trans))
3169                 btrfs_end_transaction(trans, root);
3170         if (not_written)
3171                 btrfs_dev_replace_stats_inc(&fs_info->dev_replace.
3172                                             num_uncorrectable_read_errors);
3173
3174         btrfs_free_path(path);
3175         kfree(nocow_ctx);
3176
3177         scrub_pending_trans_workers_dec(sctx);
3178 }
3179
3180 static int copy_nocow_pages_for_inode(u64 inum, u64 offset, u64 root, void *ctx)
3181 {
3182         unsigned long index;
3183         struct scrub_copy_nocow_ctx *nocow_ctx = ctx;
3184         int ret = 0;
3185         struct btrfs_key key;
3186         struct inode *inode = NULL;
3187         struct btrfs_root *local_root;
3188         u64 physical_for_dev_replace;
3189         u64 len;
3190         struct btrfs_fs_info *fs_info = nocow_ctx->sctx->dev_root->fs_info;
3191         int srcu_index;
3192
3193         key.objectid = root;
3194         key.type = BTRFS_ROOT_ITEM_KEY;
3195         key.offset = (u64)-1;
3196
3197         srcu_index = srcu_read_lock(&fs_info->subvol_srcu);
3198
3199         local_root = btrfs_read_fs_root_no_name(fs_info, &key);
3200         if (IS_ERR(local_root)) {
3201                 srcu_read_unlock(&fs_info->subvol_srcu, srcu_index);
3202                 return PTR_ERR(local_root);
3203         }
3204
3205         key.type = BTRFS_INODE_ITEM_KEY;
3206         key.objectid = inum;
3207         key.offset = 0;
3208         inode = btrfs_iget(fs_info->sb, &key, local_root, NULL);
3209         srcu_read_unlock(&fs_info->subvol_srcu, srcu_index);
3210         if (IS_ERR(inode))
3211                 return PTR_ERR(inode);
3212
3213         physical_for_dev_replace = nocow_ctx->physical_for_dev_replace;
321