562dad10dee9b894344abe65c5e7c6962d6ae112
[linux-3.10.git] / fs / btrfs / scrub.c
1 /*
2  * Copyright (C) 2011 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
29 /*
30  * This is only the first step towards a full-features scrub. It reads all
31  * extent and super block and verifies the checksums. In case a bad checksum
32  * is found or the extent cannot be read, good data will be written back if
33  * any can be found.
34  *
35  * Future enhancements:
36  *  - In case an unrepairable extent is encountered, track which files are
37  *    affected and report them
38  *  - In case of a read error on files with nodatasum, map the file and read
39  *    the extent to trigger a writeback of the good copy
40  *  - track and record media errors, throw out bad devices
41  *  - add a mode to also read unallocated space
42  */
43
44 struct scrub_bio;
45 struct scrub_page;
46 struct scrub_dev;
47 static void scrub_bio_end_io(struct bio *bio, int err);
48 static void scrub_checksum(struct btrfs_work *work);
49 static int scrub_checksum_data(struct scrub_dev *sdev,
50                                struct scrub_page *spag, void *buffer);
51 static int scrub_checksum_tree_block(struct scrub_dev *sdev,
52                                      struct scrub_page *spag, u64 logical,
53                                      void *buffer);
54 static int scrub_checksum_super(struct scrub_bio *sbio, void *buffer);
55 static int scrub_fixup_check(struct scrub_bio *sbio, int ix);
56 static void scrub_fixup_end_io(struct bio *bio, int err);
57 static int scrub_fixup_io(int rw, struct block_device *bdev, sector_t sector,
58                           struct page *page);
59 static void scrub_fixup(struct scrub_bio *sbio, int ix);
60
61 #define SCRUB_PAGES_PER_BIO     16      /* 64k per bio */
62 #define SCRUB_BIOS_PER_DEV      16      /* 1 MB per device in flight */
63
64 struct scrub_page {
65         u64                     flags;  /* extent flags */
66         u64                     generation;
67         int                     mirror_num;
68         int                     have_csum;
69         u8                      csum[BTRFS_CSUM_SIZE];
70 };
71
72 struct scrub_bio {
73         int                     index;
74         struct scrub_dev        *sdev;
75         struct bio              *bio;
76         int                     err;
77         u64                     logical;
78         u64                     physical;
79         struct scrub_page       spag[SCRUB_PAGES_PER_BIO];
80         u64                     count;
81         int                     next_free;
82         struct btrfs_work       work;
83 };
84
85 struct scrub_dev {
86         struct scrub_bio        *bios[SCRUB_BIOS_PER_DEV];
87         struct btrfs_device     *dev;
88         int                     first_free;
89         int                     curr;
90         atomic_t                in_flight;
91         atomic_t                fixup_cnt;
92         spinlock_t              list_lock;
93         wait_queue_head_t       list_wait;
94         u16                     csum_size;
95         struct list_head        csum_list;
96         atomic_t                cancel_req;
97         int                     readonly;
98         /*
99          * statistics
100          */
101         struct btrfs_scrub_progress stat;
102         spinlock_t              stat_lock;
103 };
104
105 struct scrub_fixup_nodatasum {
106         struct scrub_dev        *sdev;
107         u64                     logical;
108         struct btrfs_root       *root;
109         struct btrfs_work       work;
110         int                     mirror_num;
111 };
112
113 struct scrub_warning {
114         struct btrfs_path       *path;
115         u64                     extent_item_size;
116         char                    *scratch_buf;
117         char                    *msg_buf;
118         const char              *errstr;
119         sector_t                sector;
120         u64                     logical;
121         struct btrfs_device     *dev;
122         int                     msg_bufsize;
123         int                     scratch_bufsize;
124 };
125
126 static void scrub_free_csums(struct scrub_dev *sdev)
127 {
128         while (!list_empty(&sdev->csum_list)) {
129                 struct btrfs_ordered_sum *sum;
130                 sum = list_first_entry(&sdev->csum_list,
131                                        struct btrfs_ordered_sum, list);
132                 list_del(&sum->list);
133                 kfree(sum);
134         }
135 }
136
137 static void scrub_free_bio(struct bio *bio)
138 {
139         int i;
140         struct page *last_page = NULL;
141
142         if (!bio)
143                 return;
144
145         for (i = 0; i < bio->bi_vcnt; ++i) {
146                 if (bio->bi_io_vec[i].bv_page == last_page)
147                         continue;
148                 last_page = bio->bi_io_vec[i].bv_page;
149                 __free_page(last_page);
150         }
151         bio_put(bio);
152 }
153
154 static noinline_for_stack void scrub_free_dev(struct scrub_dev *sdev)
155 {
156         int i;
157
158         if (!sdev)
159                 return;
160
161         for (i = 0; i < SCRUB_BIOS_PER_DEV; ++i) {
162                 struct scrub_bio *sbio = sdev->bios[i];
163
164                 if (!sbio)
165                         break;
166
167                 scrub_free_bio(sbio->bio);
168                 kfree(sbio);
169         }
170
171         scrub_free_csums(sdev);
172         kfree(sdev);
173 }
174
175 static noinline_for_stack
176 struct scrub_dev *scrub_setup_dev(struct btrfs_device *dev)
177 {
178         struct scrub_dev *sdev;
179         int             i;
180         struct btrfs_fs_info *fs_info = dev->dev_root->fs_info;
181
182         sdev = kzalloc(sizeof(*sdev), GFP_NOFS);
183         if (!sdev)
184                 goto nomem;
185         sdev->dev = dev;
186         for (i = 0; i < SCRUB_BIOS_PER_DEV; ++i) {
187                 struct scrub_bio *sbio;
188
189                 sbio = kzalloc(sizeof(*sbio), GFP_NOFS);
190                 if (!sbio)
191                         goto nomem;
192                 sdev->bios[i] = sbio;
193
194                 sbio->index = i;
195                 sbio->sdev = sdev;
196                 sbio->count = 0;
197                 sbio->work.func = scrub_checksum;
198
199                 if (i != SCRUB_BIOS_PER_DEV-1)
200                         sdev->bios[i]->next_free = i + 1;
201                 else
202                         sdev->bios[i]->next_free = -1;
203         }
204         sdev->first_free = 0;
205         sdev->curr = -1;
206         atomic_set(&sdev->in_flight, 0);
207         atomic_set(&sdev->fixup_cnt, 0);
208         atomic_set(&sdev->cancel_req, 0);
209         sdev->csum_size = btrfs_super_csum_size(fs_info->super_copy);
210         INIT_LIST_HEAD(&sdev->csum_list);
211
212         spin_lock_init(&sdev->list_lock);
213         spin_lock_init(&sdev->stat_lock);
214         init_waitqueue_head(&sdev->list_wait);
215         return sdev;
216
217 nomem:
218         scrub_free_dev(sdev);
219         return ERR_PTR(-ENOMEM);
220 }
221
222 static int scrub_print_warning_inode(u64 inum, u64 offset, u64 root, void *ctx)
223 {
224         u64 isize;
225         u32 nlink;
226         int ret;
227         int i;
228         struct extent_buffer *eb;
229         struct btrfs_inode_item *inode_item;
230         struct scrub_warning *swarn = ctx;
231         struct btrfs_fs_info *fs_info = swarn->dev->dev_root->fs_info;
232         struct inode_fs_paths *ipath = NULL;
233         struct btrfs_root *local_root;
234         struct btrfs_key root_key;
235
236         root_key.objectid = root;
237         root_key.type = BTRFS_ROOT_ITEM_KEY;
238         root_key.offset = (u64)-1;
239         local_root = btrfs_read_fs_root_no_name(fs_info, &root_key);
240         if (IS_ERR(local_root)) {
241                 ret = PTR_ERR(local_root);
242                 goto err;
243         }
244
245         ret = inode_item_info(inum, 0, local_root, swarn->path);
246         if (ret) {
247                 btrfs_release_path(swarn->path);
248                 goto err;
249         }
250
251         eb = swarn->path->nodes[0];
252         inode_item = btrfs_item_ptr(eb, swarn->path->slots[0],
253                                         struct btrfs_inode_item);
254         isize = btrfs_inode_size(eb, inode_item);
255         nlink = btrfs_inode_nlink(eb, inode_item);
256         btrfs_release_path(swarn->path);
257
258         ipath = init_ipath(4096, local_root, swarn->path);
259         ret = paths_from_inode(inum, ipath);
260
261         if (ret < 0)
262                 goto err;
263
264         /*
265          * we deliberately ignore the bit ipath might have been too small to
266          * hold all of the paths here
267          */
268         for (i = 0; i < ipath->fspath->elem_cnt; ++i)
269                 printk(KERN_WARNING "btrfs: %s at logical %llu on dev "
270                         "%s, sector %llu, root %llu, inode %llu, offset %llu, "
271                         "length %llu, links %u (path: %s)\n", swarn->errstr,
272                         swarn->logical, swarn->dev->name,
273                         (unsigned long long)swarn->sector, root, inum, offset,
274                         min(isize - offset, (u64)PAGE_SIZE), nlink,
275                         (char *)ipath->fspath->val[i]);
276
277         free_ipath(ipath);
278         return 0;
279
280 err:
281         printk(KERN_WARNING "btrfs: %s at logical %llu on dev "
282                 "%s, sector %llu, root %llu, inode %llu, offset %llu: path "
283                 "resolving failed with ret=%d\n", swarn->errstr,
284                 swarn->logical, swarn->dev->name,
285                 (unsigned long long)swarn->sector, root, inum, offset, ret);
286
287         free_ipath(ipath);
288         return 0;
289 }
290
291 static void scrub_print_warning(const char *errstr, struct scrub_bio *sbio,
292                                 int ix)
293 {
294         struct btrfs_device *dev = sbio->sdev->dev;
295         struct btrfs_fs_info *fs_info = dev->dev_root->fs_info;
296         struct btrfs_path *path;
297         struct btrfs_key found_key;
298         struct extent_buffer *eb;
299         struct btrfs_extent_item *ei;
300         struct scrub_warning swarn;
301         u32 item_size;
302         int ret;
303         u64 ref_root;
304         u8 ref_level;
305         unsigned long ptr = 0;
306         const int bufsize = 4096;
307         u64 extent_offset;
308
309         path = btrfs_alloc_path();
310
311         swarn.scratch_buf = kmalloc(bufsize, GFP_NOFS);
312         swarn.msg_buf = kmalloc(bufsize, GFP_NOFS);
313         swarn.sector = (sbio->physical + ix * PAGE_SIZE) >> 9;
314         swarn.logical = sbio->logical + ix * PAGE_SIZE;
315         swarn.errstr = errstr;
316         swarn.dev = dev;
317         swarn.msg_bufsize = bufsize;
318         swarn.scratch_bufsize = bufsize;
319
320         if (!path || !swarn.scratch_buf || !swarn.msg_buf)
321                 goto out;
322
323         ret = extent_from_logical(fs_info, swarn.logical, path, &found_key);
324         if (ret < 0)
325                 goto out;
326
327         extent_offset = swarn.logical - found_key.objectid;
328         swarn.extent_item_size = found_key.offset;
329
330         eb = path->nodes[0];
331         ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
332         item_size = btrfs_item_size_nr(eb, path->slots[0]);
333
334         if (ret & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
335                 do {
336                         ret = tree_backref_for_extent(&ptr, eb, ei, item_size,
337                                                         &ref_root, &ref_level);
338                         printk(KERN_WARNING "%s at logical %llu on dev %s, "
339                                 "sector %llu: metadata %s (level %d) in tree "
340                                 "%llu\n", errstr, swarn.logical, dev->name,
341                                 (unsigned long long)swarn.sector,
342                                 ref_level ? "node" : "leaf",
343                                 ret < 0 ? -1 : ref_level,
344                                 ret < 0 ? -1 : ref_root);
345                 } while (ret != 1);
346         } else {
347                 swarn.path = path;
348                 iterate_extent_inodes(fs_info, path, found_key.objectid,
349                                         extent_offset,
350                                         scrub_print_warning_inode, &swarn);
351         }
352
353 out:
354         btrfs_free_path(path);
355         kfree(swarn.scratch_buf);
356         kfree(swarn.msg_buf);
357 }
358
359 static int scrub_fixup_readpage(u64 inum, u64 offset, u64 root, void *ctx)
360 {
361         struct page *page = NULL;
362         unsigned long index;
363         struct scrub_fixup_nodatasum *fixup = ctx;
364         int ret;
365         int corrected = 0;
366         struct btrfs_key key;
367         struct inode *inode = NULL;
368         u64 end = offset + PAGE_SIZE - 1;
369         struct btrfs_root *local_root;
370
371         key.objectid = root;
372         key.type = BTRFS_ROOT_ITEM_KEY;
373         key.offset = (u64)-1;
374         local_root = btrfs_read_fs_root_no_name(fixup->root->fs_info, &key);
375         if (IS_ERR(local_root))
376                 return PTR_ERR(local_root);
377
378         key.type = BTRFS_INODE_ITEM_KEY;
379         key.objectid = inum;
380         key.offset = 0;
381         inode = btrfs_iget(fixup->root->fs_info->sb, &key, local_root, NULL);
382         if (IS_ERR(inode))
383                 return PTR_ERR(inode);
384
385         index = offset >> PAGE_CACHE_SHIFT;
386
387         page = find_or_create_page(inode->i_mapping, index, GFP_NOFS);
388         if (!page) {
389                 ret = -ENOMEM;
390                 goto out;
391         }
392
393         if (PageUptodate(page)) {
394                 struct btrfs_mapping_tree *map_tree;
395                 if (PageDirty(page)) {
396                         /*
397                          * we need to write the data to the defect sector. the
398                          * data that was in that sector is not in memory,
399                          * because the page was modified. we must not write the
400                          * modified page to that sector.
401                          *
402                          * TODO: what could be done here: wait for the delalloc
403                          *       runner to write out that page (might involve
404                          *       COW) and see whether the sector is still
405                          *       referenced afterwards.
406                          *
407                          * For the meantime, we'll treat this error
408                          * incorrectable, although there is a chance that a
409                          * later scrub will find the bad sector again and that
410                          * there's no dirty page in memory, then.
411                          */
412                         ret = -EIO;
413                         goto out;
414                 }
415                 map_tree = &BTRFS_I(inode)->root->fs_info->mapping_tree;
416                 ret = repair_io_failure(map_tree, offset, PAGE_SIZE,
417                                         fixup->logical, page,
418                                         fixup->mirror_num);
419                 unlock_page(page);
420                 corrected = !ret;
421         } else {
422                 /*
423                  * we need to get good data first. the general readpage path
424                  * will call repair_io_failure for us, we just have to make
425                  * sure we read the bad mirror.
426                  */
427                 ret = set_extent_bits(&BTRFS_I(inode)->io_tree, offset, end,
428                                         EXTENT_DAMAGED, GFP_NOFS);
429                 if (ret) {
430                         /* set_extent_bits should give proper error */
431                         WARN_ON(ret > 0);
432                         if (ret > 0)
433                                 ret = -EFAULT;
434                         goto out;
435                 }
436
437                 ret = extent_read_full_page(&BTRFS_I(inode)->io_tree, page,
438                                                 btrfs_get_extent,
439                                                 fixup->mirror_num);
440                 wait_on_page_locked(page);
441
442                 corrected = !test_range_bit(&BTRFS_I(inode)->io_tree, offset,
443                                                 end, EXTENT_DAMAGED, 0, NULL);
444                 if (!corrected)
445                         clear_extent_bits(&BTRFS_I(inode)->io_tree, offset, end,
446                                                 EXTENT_DAMAGED, GFP_NOFS);
447         }
448
449 out:
450         if (page)
451                 put_page(page);
452         if (inode)
453                 iput(inode);
454
455         if (ret < 0)
456                 return ret;
457
458         if (ret == 0 && corrected) {
459                 /*
460                  * we only need to call readpage for one of the inodes belonging
461                  * to this extent. so make iterate_extent_inodes stop
462                  */
463                 return 1;
464         }
465
466         return -EIO;
467 }
468
469 static void scrub_fixup_nodatasum(struct btrfs_work *work)
470 {
471         int ret;
472         struct scrub_fixup_nodatasum *fixup;
473         struct scrub_dev *sdev;
474         struct btrfs_trans_handle *trans = NULL;
475         struct btrfs_fs_info *fs_info;
476         struct btrfs_path *path;
477         int uncorrectable = 0;
478
479         fixup = container_of(work, struct scrub_fixup_nodatasum, work);
480         sdev = fixup->sdev;
481         fs_info = fixup->root->fs_info;
482
483         path = btrfs_alloc_path();
484         if (!path) {
485                 spin_lock(&sdev->stat_lock);
486                 ++sdev->stat.malloc_errors;
487                 spin_unlock(&sdev->stat_lock);
488                 uncorrectable = 1;
489                 goto out;
490         }
491
492         trans = btrfs_join_transaction(fixup->root);
493         if (IS_ERR(trans)) {
494                 uncorrectable = 1;
495                 goto out;
496         }
497
498         /*
499          * the idea is to trigger a regular read through the standard path. we
500          * read a page from the (failed) logical address by specifying the
501          * corresponding copynum of the failed sector. thus, that readpage is
502          * expected to fail.
503          * that is the point where on-the-fly error correction will kick in
504          * (once it's finished) and rewrite the failed sector if a good copy
505          * can be found.
506          */
507         ret = iterate_inodes_from_logical(fixup->logical, fixup->root->fs_info,
508                                                 path, scrub_fixup_readpage,
509                                                 fixup);
510         if (ret < 0) {
511                 uncorrectable = 1;
512                 goto out;
513         }
514         WARN_ON(ret != 1);
515
516         spin_lock(&sdev->stat_lock);
517         ++sdev->stat.corrected_errors;
518         spin_unlock(&sdev->stat_lock);
519
520 out:
521         if (trans && !IS_ERR(trans))
522                 btrfs_end_transaction(trans, fixup->root);
523         if (uncorrectable) {
524                 spin_lock(&sdev->stat_lock);
525                 ++sdev->stat.uncorrectable_errors;
526                 spin_unlock(&sdev->stat_lock);
527                 printk_ratelimited(KERN_ERR "btrfs: unable to fixup "
528                                         "(nodatasum) error at logical %llu\n",
529                                         fixup->logical);
530         }
531
532         btrfs_free_path(path);
533         kfree(fixup);
534
535         /* see caller why we're pretending to be paused in the scrub counters */
536         mutex_lock(&fs_info->scrub_lock);
537         atomic_dec(&fs_info->scrubs_running);
538         atomic_dec(&fs_info->scrubs_paused);
539         mutex_unlock(&fs_info->scrub_lock);
540         atomic_dec(&sdev->fixup_cnt);
541         wake_up(&fs_info->scrub_pause_wait);
542         wake_up(&sdev->list_wait);
543 }
544
545 /*
546  * scrub_recheck_error gets called when either verification of the page
547  * failed or the bio failed to read, e.g. with EIO. In the latter case,
548  * recheck_error gets called for every page in the bio, even though only
549  * one may be bad
550  */
551 static int scrub_recheck_error(struct scrub_bio *sbio, int ix)
552 {
553         struct scrub_dev *sdev = sbio->sdev;
554         u64 sector = (sbio->physical + ix * PAGE_SIZE) >> 9;
555         static DEFINE_RATELIMIT_STATE(_rs, DEFAULT_RATELIMIT_INTERVAL,
556                                         DEFAULT_RATELIMIT_BURST);
557
558         if (sbio->err) {
559                 if (scrub_fixup_io(READ, sbio->sdev->dev->bdev, sector,
560                                    sbio->bio->bi_io_vec[ix].bv_page) == 0) {
561                         if (scrub_fixup_check(sbio, ix) == 0)
562                                 return 0;
563                 }
564                 if (__ratelimit(&_rs))
565                         scrub_print_warning("i/o error", sbio, ix);
566         } else {
567                 if (__ratelimit(&_rs))
568                         scrub_print_warning("checksum error", sbio, ix);
569         }
570
571         spin_lock(&sdev->stat_lock);
572         ++sdev->stat.read_errors;
573         spin_unlock(&sdev->stat_lock);
574
575         scrub_fixup(sbio, ix);
576         return 1;
577 }
578
579 static int scrub_fixup_check(struct scrub_bio *sbio, int ix)
580 {
581         int ret = 1;
582         struct page *page;
583         void *buffer;
584         u64 flags = sbio->spag[ix].flags;
585
586         page = sbio->bio->bi_io_vec[ix].bv_page;
587         buffer = kmap_atomic(page, KM_USER0);
588         if (flags & BTRFS_EXTENT_FLAG_DATA) {
589                 ret = scrub_checksum_data(sbio->sdev,
590                                           sbio->spag + ix, buffer);
591         } else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
592                 ret = scrub_checksum_tree_block(sbio->sdev,
593                                                 sbio->spag + ix,
594                                                 sbio->logical + ix * PAGE_SIZE,
595                                                 buffer);
596         } else {
597                 WARN_ON(1);
598         }
599         kunmap_atomic(buffer, KM_USER0);
600
601         return ret;
602 }
603
604 static void scrub_fixup_end_io(struct bio *bio, int err)
605 {
606         complete((struct completion *)bio->bi_private);
607 }
608
609 static void scrub_fixup(struct scrub_bio *sbio, int ix)
610 {
611         struct scrub_dev *sdev = sbio->sdev;
612         struct btrfs_fs_info *fs_info = sdev->dev->dev_root->fs_info;
613         struct btrfs_mapping_tree *map_tree = &fs_info->mapping_tree;
614         struct btrfs_bio *bbio = NULL;
615         struct scrub_fixup_nodatasum *fixup;
616         u64 logical = sbio->logical + ix * PAGE_SIZE;
617         u64 length;
618         int i;
619         int ret;
620         DECLARE_COMPLETION_ONSTACK(complete);
621
622         if ((sbio->spag[ix].flags & BTRFS_EXTENT_FLAG_DATA) &&
623             (sbio->spag[ix].have_csum == 0)) {
624                 fixup = kzalloc(sizeof(*fixup), GFP_NOFS);
625                 if (!fixup)
626                         goto uncorrectable;
627                 fixup->sdev = sdev;
628                 fixup->logical = logical;
629                 fixup->root = fs_info->extent_root;
630                 fixup->mirror_num = sbio->spag[ix].mirror_num;
631                 /*
632                  * increment scrubs_running to prevent cancel requests from
633                  * completing as long as a fixup worker is running. we must also
634                  * increment scrubs_paused to prevent deadlocking on pause
635                  * requests used for transactions commits (as the worker uses a
636                  * transaction context). it is safe to regard the fixup worker
637                  * as paused for all matters practical. effectively, we only
638                  * avoid cancellation requests from completing.
639                  */
640                 mutex_lock(&fs_info->scrub_lock);
641                 atomic_inc(&fs_info->scrubs_running);
642                 atomic_inc(&fs_info->scrubs_paused);
643                 mutex_unlock(&fs_info->scrub_lock);
644                 atomic_inc(&sdev->fixup_cnt);
645                 fixup->work.func = scrub_fixup_nodatasum;
646                 btrfs_queue_worker(&fs_info->scrub_workers, &fixup->work);
647                 return;
648         }
649
650         length = PAGE_SIZE;
651         ret = btrfs_map_block(map_tree, REQ_WRITE, logical, &length,
652                               &bbio, 0);
653         if (ret || !bbio || length < PAGE_SIZE) {
654                 printk(KERN_ERR
655                        "scrub_fixup: btrfs_map_block failed us for %llu\n",
656                        (unsigned long long)logical);
657                 WARN_ON(1);
658                 return;
659         }
660
661         if (bbio->num_stripes == 1)
662                 /* there aren't any replicas */
663                 goto uncorrectable;
664
665         /*
666          * first find a good copy
667          */
668         for (i = 0; i < bbio->num_stripes; ++i) {
669                 if (i + 1 == sbio->spag[ix].mirror_num)
670                         continue;
671
672                 if (scrub_fixup_io(READ, bbio->stripes[i].dev->bdev,
673                                    bbio->stripes[i].physical >> 9,
674                                    sbio->bio->bi_io_vec[ix].bv_page)) {
675                         /* I/O-error, this is not a good copy */
676                         continue;
677                 }
678
679                 if (scrub_fixup_check(sbio, ix) == 0)
680                         break;
681         }
682         if (i == bbio->num_stripes)
683                 goto uncorrectable;
684
685         if (!sdev->readonly) {
686                 /*
687                  * bi_io_vec[ix].bv_page now contains good data, write it back
688                  */
689                 if (scrub_fixup_io(WRITE, sdev->dev->bdev,
690                                    (sbio->physical + ix * PAGE_SIZE) >> 9,
691                                    sbio->bio->bi_io_vec[ix].bv_page)) {
692                         /* I/O-error, writeback failed, give up */
693                         goto uncorrectable;
694                 }
695         }
696
697         kfree(bbio);
698         spin_lock(&sdev->stat_lock);
699         ++sdev->stat.corrected_errors;
700         spin_unlock(&sdev->stat_lock);
701
702         printk_ratelimited(KERN_ERR "btrfs: fixed up error at logical %llu\n",
703                                (unsigned long long)logical);
704         return;
705
706 uncorrectable:
707         kfree(bbio);
708         spin_lock(&sdev->stat_lock);
709         ++sdev->stat.uncorrectable_errors;
710         spin_unlock(&sdev->stat_lock);
711
712         printk_ratelimited(KERN_ERR "btrfs: unable to fixup (regular) error at "
713                                 "logical %llu\n", (unsigned long long)logical);
714 }
715
716 static int scrub_fixup_io(int rw, struct block_device *bdev, sector_t sector,
717                          struct page *page)
718 {
719         struct bio *bio = NULL;
720         int ret;
721         DECLARE_COMPLETION_ONSTACK(complete);
722
723         bio = bio_alloc(GFP_NOFS, 1);
724         bio->bi_bdev = bdev;
725         bio->bi_sector = sector;
726         bio_add_page(bio, page, PAGE_SIZE, 0);
727         bio->bi_end_io = scrub_fixup_end_io;
728         bio->bi_private = &complete;
729         submit_bio(rw, bio);
730
731         /* this will also unplug the queue */
732         wait_for_completion(&complete);
733
734         ret = !test_bit(BIO_UPTODATE, &bio->bi_flags);
735         bio_put(bio);
736         return ret;
737 }
738
739 static void scrub_bio_end_io(struct bio *bio, int err)
740 {
741         struct scrub_bio *sbio = bio->bi_private;
742         struct scrub_dev *sdev = sbio->sdev;
743         struct btrfs_fs_info *fs_info = sdev->dev->dev_root->fs_info;
744
745         sbio->err = err;
746         sbio->bio = bio;
747
748         btrfs_queue_worker(&fs_info->scrub_workers, &sbio->work);
749 }
750
751 static void scrub_checksum(struct btrfs_work *work)
752 {
753         struct scrub_bio *sbio = container_of(work, struct scrub_bio, work);
754         struct scrub_dev *sdev = sbio->sdev;
755         struct page *page;
756         void *buffer;
757         int i;
758         u64 flags;
759         u64 logical;
760         int ret;
761
762         if (sbio->err) {
763                 ret = 0;
764                 for (i = 0; i < sbio->count; ++i)
765                         ret |= scrub_recheck_error(sbio, i);
766                 if (!ret) {
767                         spin_lock(&sdev->stat_lock);
768                         ++sdev->stat.unverified_errors;
769                         spin_unlock(&sdev->stat_lock);
770                 }
771
772                 sbio->bio->bi_flags &= ~(BIO_POOL_MASK - 1);
773                 sbio->bio->bi_flags |= 1 << BIO_UPTODATE;
774                 sbio->bio->bi_phys_segments = 0;
775                 sbio->bio->bi_idx = 0;
776
777                 for (i = 0; i < sbio->count; i++) {
778                         struct bio_vec *bi;
779                         bi = &sbio->bio->bi_io_vec[i];
780                         bi->bv_offset = 0;
781                         bi->bv_len = PAGE_SIZE;
782                 }
783                 goto out;
784         }
785         for (i = 0; i < sbio->count; ++i) {
786                 page = sbio->bio->bi_io_vec[i].bv_page;
787                 buffer = kmap_atomic(page, KM_USER0);
788                 flags = sbio->spag[i].flags;
789                 logical = sbio->logical + i * PAGE_SIZE;
790                 ret = 0;
791                 if (flags & BTRFS_EXTENT_FLAG_DATA) {
792                         ret = scrub_checksum_data(sdev, sbio->spag + i, buffer);
793                 } else if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
794                         ret = scrub_checksum_tree_block(sdev, sbio->spag + i,
795                                                         logical, buffer);
796                 } else if (flags & BTRFS_EXTENT_FLAG_SUPER) {
797                         BUG_ON(i);
798                         (void)scrub_checksum_super(sbio, buffer);
799                 } else {
800                         WARN_ON(1);
801                 }
802                 kunmap_atomic(buffer, KM_USER0);
803                 if (ret) {
804                         ret = scrub_recheck_error(sbio, i);
805                         if (!ret) {
806                                 spin_lock(&sdev->stat_lock);
807                                 ++sdev->stat.unverified_errors;
808                                 spin_unlock(&sdev->stat_lock);
809                         }
810                 }
811         }
812
813 out:
814         scrub_free_bio(sbio->bio);
815         sbio->bio = NULL;
816         spin_lock(&sdev->list_lock);
817         sbio->next_free = sdev->first_free;
818         sdev->first_free = sbio->index;
819         spin_unlock(&sdev->list_lock);
820         atomic_dec(&sdev->in_flight);
821         wake_up(&sdev->list_wait);
822 }
823
824 static int scrub_checksum_data(struct scrub_dev *sdev,
825                                struct scrub_page *spag, void *buffer)
826 {
827         u8 csum[BTRFS_CSUM_SIZE];
828         u32 crc = ~(u32)0;
829         int fail = 0;
830         struct btrfs_root *root = sdev->dev->dev_root;
831
832         if (!spag->have_csum)
833                 return 0;
834
835         crc = btrfs_csum_data(root, buffer, crc, PAGE_SIZE);
836         btrfs_csum_final(crc, csum);
837         if (memcmp(csum, spag->csum, sdev->csum_size))
838                 fail = 1;
839
840         spin_lock(&sdev->stat_lock);
841         ++sdev->stat.data_extents_scrubbed;
842         sdev->stat.data_bytes_scrubbed += PAGE_SIZE;
843         if (fail)
844                 ++sdev->stat.csum_errors;
845         spin_unlock(&sdev->stat_lock);
846
847         return fail;
848 }
849
850 static int scrub_checksum_tree_block(struct scrub_dev *sdev,
851                                      struct scrub_page *spag, u64 logical,
852                                      void *buffer)
853 {
854         struct btrfs_header *h;
855         struct btrfs_root *root = sdev->dev->dev_root;
856         struct btrfs_fs_info *fs_info = root->fs_info;
857         u8 csum[BTRFS_CSUM_SIZE];
858         u32 crc = ~(u32)0;
859         int fail = 0;
860         int crc_fail = 0;
861
862         /*
863          * we don't use the getter functions here, as we
864          * a) don't have an extent buffer and
865          * b) the page is already kmapped
866          */
867         h = (struct btrfs_header *)buffer;
868
869         if (logical != le64_to_cpu(h->bytenr))
870                 ++fail;
871
872         if (spag->generation != le64_to_cpu(h->generation))
873                 ++fail;
874
875         if (memcmp(h->fsid, fs_info->fsid, BTRFS_UUID_SIZE))
876                 ++fail;
877
878         if (memcmp(h->chunk_tree_uuid, fs_info->chunk_tree_uuid,
879                    BTRFS_UUID_SIZE))
880                 ++fail;
881
882         crc = btrfs_csum_data(root, buffer + BTRFS_CSUM_SIZE, crc,
883                               PAGE_SIZE - BTRFS_CSUM_SIZE);
884         btrfs_csum_final(crc, csum);
885         if (memcmp(csum, h->csum, sdev->csum_size))
886                 ++crc_fail;
887
888         spin_lock(&sdev->stat_lock);
889         ++sdev->stat.tree_extents_scrubbed;
890         sdev->stat.tree_bytes_scrubbed += PAGE_SIZE;
891         if (crc_fail)
892                 ++sdev->stat.csum_errors;
893         if (fail)
894                 ++sdev->stat.verify_errors;
895         spin_unlock(&sdev->stat_lock);
896
897         return fail || crc_fail;
898 }
899
900 static int scrub_checksum_super(struct scrub_bio *sbio, void *buffer)
901 {
902         struct btrfs_super_block *s;
903         u64 logical;
904         struct scrub_dev *sdev = sbio->sdev;
905         struct btrfs_root *root = sdev->dev->dev_root;
906         struct btrfs_fs_info *fs_info = root->fs_info;
907         u8 csum[BTRFS_CSUM_SIZE];
908         u32 crc = ~(u32)0;
909         int fail = 0;
910
911         s = (struct btrfs_super_block *)buffer;
912         logical = sbio->logical;
913
914         if (logical != le64_to_cpu(s->bytenr))
915                 ++fail;
916
917         if (sbio->spag[0].generation != le64_to_cpu(s->generation))
918                 ++fail;
919
920         if (memcmp(s->fsid, fs_info->fsid, BTRFS_UUID_SIZE))
921                 ++fail;
922
923         crc = btrfs_csum_data(root, buffer + BTRFS_CSUM_SIZE, crc,
924                               PAGE_SIZE - BTRFS_CSUM_SIZE);
925         btrfs_csum_final(crc, csum);
926         if (memcmp(csum, s->csum, sbio->sdev->csum_size))
927                 ++fail;
928
929         if (fail) {
930                 /*
931                  * if we find an error in a super block, we just report it.
932                  * They will get written with the next transaction commit
933                  * anyway
934                  */
935                 spin_lock(&sdev->stat_lock);
936                 ++sdev->stat.super_errors;
937                 spin_unlock(&sdev->stat_lock);
938         }
939
940         return fail;
941 }
942
943 static int scrub_submit(struct scrub_dev *sdev)
944 {
945         struct scrub_bio *sbio;
946         struct bio *bio;
947         int i;
948
949         if (sdev->curr == -1)
950                 return 0;
951
952         sbio = sdev->bios[sdev->curr];
953
954         bio = bio_alloc(GFP_NOFS, sbio->count);
955         if (!bio)
956                 goto nomem;
957
958         bio->bi_private = sbio;
959         bio->bi_end_io = scrub_bio_end_io;
960         bio->bi_bdev = sdev->dev->bdev;
961         bio->bi_sector = sbio->physical >> 9;
962
963         for (i = 0; i < sbio->count; ++i) {
964                 struct page *page;
965                 int ret;
966
967                 page = alloc_page(GFP_NOFS);
968                 if (!page)
969                         goto nomem;
970
971                 ret = bio_add_page(bio, page, PAGE_SIZE, 0);
972                 if (!ret) {
973                         __free_page(page);
974                         goto nomem;
975                 }
976         }
977
978         sbio->err = 0;
979         sdev->curr = -1;
980         atomic_inc(&sdev->in_flight);
981
982         submit_bio(READ, bio);
983
984         return 0;
985
986 nomem:
987         scrub_free_bio(bio);
988
989         return -ENOMEM;
990 }
991
992 static int scrub_page(struct scrub_dev *sdev, u64 logical, u64 len,
993                       u64 physical, u64 flags, u64 gen, int mirror_num,
994                       u8 *csum, int force)
995 {
996         struct scrub_bio *sbio;
997
998 again:
999         /*
1000          * grab a fresh bio or wait for one to become available
1001          */
1002         while (sdev->curr == -1) {
1003                 spin_lock(&sdev->list_lock);
1004                 sdev->curr = sdev->first_free;
1005                 if (sdev->curr != -1) {
1006                         sdev->first_free = sdev->bios[sdev->curr]->next_free;
1007                         sdev->bios[sdev->curr]->next_free = -1;
1008                         sdev->bios[sdev->curr]->count = 0;
1009                         spin_unlock(&sdev->list_lock);
1010                 } else {
1011                         spin_unlock(&sdev->list_lock);
1012                         wait_event(sdev->list_wait, sdev->first_free != -1);
1013                 }
1014         }
1015         sbio = sdev->bios[sdev->curr];
1016         if (sbio->count == 0) {
1017                 sbio->physical = physical;
1018                 sbio->logical = logical;
1019         } else if (sbio->physical + sbio->count * PAGE_SIZE != physical ||
1020                    sbio->logical + sbio->count * PAGE_SIZE != logical) {
1021                 int ret;
1022
1023                 ret = scrub_submit(sdev);
1024                 if (ret)
1025                         return ret;
1026                 goto again;
1027         }
1028         sbio->spag[sbio->count].flags = flags;
1029         sbio->spag[sbio->count].generation = gen;
1030         sbio->spag[sbio->count].have_csum = 0;
1031         sbio->spag[sbio->count].mirror_num = mirror_num;
1032         if (csum) {
1033                 sbio->spag[sbio->count].have_csum = 1;
1034                 memcpy(sbio->spag[sbio->count].csum, csum, sdev->csum_size);
1035         }
1036         ++sbio->count;
1037         if (sbio->count == SCRUB_PAGES_PER_BIO || force) {
1038                 int ret;
1039
1040                 ret = scrub_submit(sdev);
1041                 if (ret)
1042                         return ret;
1043         }
1044
1045         return 0;
1046 }
1047
1048 static int scrub_find_csum(struct scrub_dev *sdev, u64 logical, u64 len,
1049                            u8 *csum)
1050 {
1051         struct btrfs_ordered_sum *sum = NULL;
1052         int ret = 0;
1053         unsigned long i;
1054         unsigned long num_sectors;
1055         u32 sectorsize = sdev->dev->dev_root->sectorsize;
1056
1057         while (!list_empty(&sdev->csum_list)) {
1058                 sum = list_first_entry(&sdev->csum_list,
1059                                        struct btrfs_ordered_sum, list);
1060                 if (sum->bytenr > logical)
1061                         return 0;
1062                 if (sum->bytenr + sum->len > logical)
1063                         break;
1064
1065                 ++sdev->stat.csum_discards;
1066                 list_del(&sum->list);
1067                 kfree(sum);
1068                 sum = NULL;
1069         }
1070         if (!sum)
1071                 return 0;
1072
1073         num_sectors = sum->len / sectorsize;
1074         for (i = 0; i < num_sectors; ++i) {
1075                 if (sum->sums[i].bytenr == logical) {
1076                         memcpy(csum, &sum->sums[i].sum, sdev->csum_size);
1077                         ret = 1;
1078                         break;
1079                 }
1080         }
1081         if (ret && i == num_sectors - 1) {
1082                 list_del(&sum->list);
1083                 kfree(sum);
1084         }
1085         return ret;
1086 }
1087
1088 /* scrub extent tries to collect up to 64 kB for each bio */
1089 static int scrub_extent(struct scrub_dev *sdev, u64 logical, u64 len,
1090                         u64 physical, u64 flags, u64 gen, int mirror_num)
1091 {
1092         int ret;
1093         u8 csum[BTRFS_CSUM_SIZE];
1094
1095         while (len) {
1096                 u64 l = min_t(u64, len, PAGE_SIZE);
1097                 int have_csum = 0;
1098
1099                 if (flags & BTRFS_EXTENT_FLAG_DATA) {
1100                         /* push csums to sbio */
1101                         have_csum = scrub_find_csum(sdev, logical, l, csum);
1102                         if (have_csum == 0)
1103                                 ++sdev->stat.no_csum;
1104                 }
1105                 ret = scrub_page(sdev, logical, l, physical, flags, gen,
1106                                  mirror_num, have_csum ? csum : NULL, 0);
1107                 if (ret)
1108                         return ret;
1109                 len -= l;
1110                 logical += l;
1111                 physical += l;
1112         }
1113         return 0;
1114 }
1115
1116 static noinline_for_stack int scrub_stripe(struct scrub_dev *sdev,
1117         struct map_lookup *map, int num, u64 base, u64 length)
1118 {
1119         struct btrfs_path *path;
1120         struct btrfs_fs_info *fs_info = sdev->dev->dev_root->fs_info;
1121         struct btrfs_root *root = fs_info->extent_root;
1122         struct btrfs_root *csum_root = fs_info->csum_root;
1123         struct btrfs_extent_item *extent;
1124         struct blk_plug plug;
1125         u64 flags;
1126         int ret;
1127         int slot;
1128         int i;
1129         u64 nstripes;
1130         struct extent_buffer *l;
1131         struct btrfs_key key;
1132         u64 physical;
1133         u64 logical;
1134         u64 generation;
1135         int mirror_num;
1136         struct reada_control *reada1;
1137         struct reada_control *reada2;
1138         struct btrfs_key key_start;
1139         struct btrfs_key key_end;
1140
1141         u64 increment = map->stripe_len;
1142         u64 offset;
1143
1144         nstripes = length;
1145         offset = 0;
1146         do_div(nstripes, map->stripe_len);
1147         if (map->type & BTRFS_BLOCK_GROUP_RAID0) {
1148                 offset = map->stripe_len * num;
1149                 increment = map->stripe_len * map->num_stripes;
1150                 mirror_num = 1;
1151         } else if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
1152                 int factor = map->num_stripes / map->sub_stripes;
1153                 offset = map->stripe_len * (num / map->sub_stripes);
1154                 increment = map->stripe_len * factor;
1155                 mirror_num = num % map->sub_stripes + 1;
1156         } else if (map->type & BTRFS_BLOCK_GROUP_RAID1) {
1157                 increment = map->stripe_len;
1158                 mirror_num = num % map->num_stripes + 1;
1159         } else if (map->type & BTRFS_BLOCK_GROUP_DUP) {
1160                 increment = map->stripe_len;
1161                 mirror_num = num % map->num_stripes + 1;
1162         } else {
1163                 increment = map->stripe_len;
1164                 mirror_num = 1;
1165         }
1166
1167         path = btrfs_alloc_path();
1168         if (!path)
1169                 return -ENOMEM;
1170
1171         path->search_commit_root = 1;
1172         path->skip_locking = 1;
1173
1174         /*
1175          * trigger the readahead for extent tree csum tree and wait for
1176          * completion. During readahead, the scrub is officially paused
1177          * to not hold off transaction commits
1178          */
1179         logical = base + offset;
1180
1181         wait_event(sdev->list_wait,
1182                    atomic_read(&sdev->in_flight) == 0);
1183         atomic_inc(&fs_info->scrubs_paused);
1184         wake_up(&fs_info->scrub_pause_wait);
1185
1186         /* FIXME it might be better to start readahead at commit root */
1187         key_start.objectid = logical;
1188         key_start.type = BTRFS_EXTENT_ITEM_KEY;
1189         key_start.offset = (u64)0;
1190         key_end.objectid = base + offset + nstripes * increment;
1191         key_end.type = BTRFS_EXTENT_ITEM_KEY;
1192         key_end.offset = (u64)0;
1193         reada1 = btrfs_reada_add(root, &key_start, &key_end);
1194
1195         key_start.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
1196         key_start.type = BTRFS_EXTENT_CSUM_KEY;
1197         key_start.offset = logical;
1198         key_end.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
1199         key_end.type = BTRFS_EXTENT_CSUM_KEY;
1200         key_end.offset = base + offset + nstripes * increment;
1201         reada2 = btrfs_reada_add(csum_root, &key_start, &key_end);
1202
1203         if (!IS_ERR(reada1))
1204                 btrfs_reada_wait(reada1);
1205         if (!IS_ERR(reada2))
1206                 btrfs_reada_wait(reada2);
1207
1208         mutex_lock(&fs_info->scrub_lock);
1209         while (atomic_read(&fs_info->scrub_pause_req)) {
1210                 mutex_unlock(&fs_info->scrub_lock);
1211                 wait_event(fs_info->scrub_pause_wait,
1212                    atomic_read(&fs_info->scrub_pause_req) == 0);
1213                 mutex_lock(&fs_info->scrub_lock);
1214         }
1215         atomic_dec(&fs_info->scrubs_paused);
1216         mutex_unlock(&fs_info->scrub_lock);
1217         wake_up(&fs_info->scrub_pause_wait);
1218
1219         /*
1220          * collect all data csums for the stripe to avoid seeking during
1221          * the scrub. This might currently (crc32) end up to be about 1MB
1222          */
1223         blk_start_plug(&plug);
1224
1225         /*
1226          * now find all extents for each stripe and scrub them
1227          */
1228         logical = base + offset;
1229         physical = map->stripes[num].physical;
1230         ret = 0;
1231         for (i = 0; i < nstripes; ++i) {
1232                 /*
1233                  * canceled?
1234                  */
1235                 if (atomic_read(&fs_info->scrub_cancel_req) ||
1236                     atomic_read(&sdev->cancel_req)) {
1237                         ret = -ECANCELED;
1238                         goto out;
1239                 }
1240                 /*
1241                  * check to see if we have to pause
1242                  */
1243                 if (atomic_read(&fs_info->scrub_pause_req)) {
1244                         /* push queued extents */
1245                         scrub_submit(sdev);
1246                         wait_event(sdev->list_wait,
1247                                    atomic_read(&sdev->in_flight) == 0);
1248                         atomic_inc(&fs_info->scrubs_paused);
1249                         wake_up(&fs_info->scrub_pause_wait);
1250                         mutex_lock(&fs_info->scrub_lock);
1251                         while (atomic_read(&fs_info->scrub_pause_req)) {
1252                                 mutex_unlock(&fs_info->scrub_lock);
1253                                 wait_event(fs_info->scrub_pause_wait,
1254                                    atomic_read(&fs_info->scrub_pause_req) == 0);
1255                                 mutex_lock(&fs_info->scrub_lock);
1256                         }
1257                         atomic_dec(&fs_info->scrubs_paused);
1258                         mutex_unlock(&fs_info->scrub_lock);
1259                         wake_up(&fs_info->scrub_pause_wait);
1260                 }
1261
1262                 ret = btrfs_lookup_csums_range(csum_root, logical,
1263                                                logical + map->stripe_len - 1,
1264                                                &sdev->csum_list, 1);
1265                 if (ret)
1266                         goto out;
1267
1268                 key.objectid = logical;
1269                 key.type = BTRFS_EXTENT_ITEM_KEY;
1270                 key.offset = (u64)0;
1271
1272                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1273                 if (ret < 0)
1274                         goto out;
1275                 if (ret > 0) {
1276                         ret = btrfs_previous_item(root, path, 0,
1277                                                   BTRFS_EXTENT_ITEM_KEY);
1278                         if (ret < 0)
1279                                 goto out;
1280                         if (ret > 0) {
1281                                 /* there's no smaller item, so stick with the
1282                                  * larger one */
1283                                 btrfs_release_path(path);
1284                                 ret = btrfs_search_slot(NULL, root, &key,
1285                                                         path, 0, 0);
1286                                 if (ret < 0)
1287                                         goto out;
1288                         }
1289                 }
1290
1291                 while (1) {
1292                         l = path->nodes[0];
1293                         slot = path->slots[0];
1294                         if (slot >= btrfs_header_nritems(l)) {
1295                                 ret = btrfs_next_leaf(root, path);
1296                                 if (ret == 0)
1297                                         continue;
1298                                 if (ret < 0)
1299                                         goto out;
1300
1301                                 break;
1302                         }
1303                         btrfs_item_key_to_cpu(l, &key, slot);
1304
1305                         if (key.objectid + key.offset <= logical)
1306                                 goto next;
1307
1308                         if (key.objectid >= logical + map->stripe_len)
1309                                 break;
1310
1311                         if (btrfs_key_type(&key) != BTRFS_EXTENT_ITEM_KEY)
1312                                 goto next;
1313
1314                         extent = btrfs_item_ptr(l, slot,
1315                                                 struct btrfs_extent_item);
1316                         flags = btrfs_extent_flags(l, extent);
1317                         generation = btrfs_extent_generation(l, extent);
1318
1319                         if (key.objectid < logical &&
1320                             (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)) {
1321                                 printk(KERN_ERR
1322                                        "btrfs scrub: tree block %llu spanning "
1323                                        "stripes, ignored. logical=%llu\n",
1324                                        (unsigned long long)key.objectid,
1325                                        (unsigned long long)logical);
1326                                 goto next;
1327                         }
1328
1329                         /*
1330                          * trim extent to this stripe
1331                          */
1332                         if (key.objectid < logical) {
1333                                 key.offset -= logical - key.objectid;
1334                                 key.objectid = logical;
1335                         }
1336                         if (key.objectid + key.offset >
1337                             logical + map->stripe_len) {
1338                                 key.offset = logical + map->stripe_len -
1339                                              key.objectid;
1340                         }
1341
1342                         ret = scrub_extent(sdev, key.objectid, key.offset,
1343                                            key.objectid - logical + physical,
1344                                            flags, generation, mirror_num);
1345                         if (ret)
1346                                 goto out;
1347
1348 next:
1349                         path->slots[0]++;
1350                 }
1351                 btrfs_release_path(path);
1352                 logical += increment;
1353                 physical += map->stripe_len;
1354                 spin_lock(&sdev->stat_lock);
1355                 sdev->stat.last_physical = physical;
1356                 spin_unlock(&sdev->stat_lock);
1357         }
1358         /* push queued extents */
1359         scrub_submit(sdev);
1360
1361 out:
1362         blk_finish_plug(&plug);
1363         btrfs_free_path(path);
1364         return ret < 0 ? ret : 0;
1365 }
1366
1367 static noinline_for_stack int scrub_chunk(struct scrub_dev *sdev,
1368         u64 chunk_tree, u64 chunk_objectid, u64 chunk_offset, u64 length)
1369 {
1370         struct btrfs_mapping_tree *map_tree =
1371                 &sdev->dev->dev_root->fs_info->mapping_tree;
1372         struct map_lookup *map;
1373         struct extent_map *em;
1374         int i;
1375         int ret = -EINVAL;
1376
1377         read_lock(&map_tree->map_tree.lock);
1378         em = lookup_extent_mapping(&map_tree->map_tree, chunk_offset, 1);
1379         read_unlock(&map_tree->map_tree.lock);
1380
1381         if (!em)
1382                 return -EINVAL;
1383
1384         map = (struct map_lookup *)em->bdev;
1385         if (em->start != chunk_offset)
1386                 goto out;
1387
1388         if (em->len < length)
1389                 goto out;
1390
1391         for (i = 0; i < map->num_stripes; ++i) {
1392                 if (map->stripes[i].dev == sdev->dev) {
1393                         ret = scrub_stripe(sdev, map, i, chunk_offset, length);
1394                         if (ret)
1395                                 goto out;
1396                 }
1397         }
1398 out:
1399         free_extent_map(em);
1400
1401         return ret;
1402 }
1403
1404 static noinline_for_stack
1405 int scrub_enumerate_chunks(struct scrub_dev *sdev, u64 start, u64 end)
1406 {
1407         struct btrfs_dev_extent *dev_extent = NULL;
1408         struct btrfs_path *path;
1409         struct btrfs_root *root = sdev->dev->dev_root;
1410         struct btrfs_fs_info *fs_info = root->fs_info;
1411         u64 length;
1412         u64 chunk_tree;
1413         u64 chunk_objectid;
1414         u64 chunk_offset;
1415         int ret;
1416         int slot;
1417         struct extent_buffer *l;
1418         struct btrfs_key key;
1419         struct btrfs_key found_key;
1420         struct btrfs_block_group_cache *cache;
1421
1422         path = btrfs_alloc_path();
1423         if (!path)
1424                 return -ENOMEM;
1425
1426         path->reada = 2;
1427         path->search_commit_root = 1;
1428         path->skip_locking = 1;
1429
1430         key.objectid = sdev->dev->devid;
1431         key.offset = 0ull;
1432         key.type = BTRFS_DEV_EXTENT_KEY;
1433
1434
1435         while (1) {
1436                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1437                 if (ret < 0)
1438                         break;
1439                 if (ret > 0) {
1440                         if (path->slots[0] >=
1441                             btrfs_header_nritems(path->nodes[0])) {
1442                                 ret = btrfs_next_leaf(root, path);
1443                                 if (ret)
1444                                         break;
1445                         }
1446                 }
1447
1448                 l = path->nodes[0];
1449                 slot = path->slots[0];
1450
1451                 btrfs_item_key_to_cpu(l, &found_key, slot);
1452
1453                 if (found_key.objectid != sdev->dev->devid)
1454                         break;
1455
1456                 if (btrfs_key_type(&found_key) != BTRFS_DEV_EXTENT_KEY)
1457                         break;
1458
1459                 if (found_key.offset >= end)
1460                         break;
1461
1462                 if (found_key.offset < key.offset)
1463                         break;
1464
1465                 dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent);
1466                 length = btrfs_dev_extent_length(l, dev_extent);
1467
1468                 if (found_key.offset + length <= start) {
1469                         key.offset = found_key.offset + length;
1470                         btrfs_release_path(path);
1471                         continue;
1472                 }
1473
1474                 chunk_tree = btrfs_dev_extent_chunk_tree(l, dev_extent);
1475                 chunk_objectid = btrfs_dev_extent_chunk_objectid(l, dev_extent);
1476                 chunk_offset = btrfs_dev_extent_chunk_offset(l, dev_extent);
1477
1478                 /*
1479                  * get a reference on the corresponding block group to prevent
1480                  * the chunk from going away while we scrub it
1481                  */
1482                 cache = btrfs_lookup_block_group(fs_info, chunk_offset);
1483                 if (!cache) {
1484                         ret = -ENOENT;
1485                         break;
1486                 }
1487                 ret = scrub_chunk(sdev, chunk_tree, chunk_objectid,
1488                                   chunk_offset, length);
1489                 btrfs_put_block_group(cache);
1490                 if (ret)
1491                         break;
1492
1493                 key.offset = found_key.offset + length;
1494                 btrfs_release_path(path);
1495         }
1496
1497         btrfs_free_path(path);
1498
1499         /*
1500          * ret can still be 1 from search_slot or next_leaf,
1501          * that's not an error
1502          */
1503         return ret < 0 ? ret : 0;
1504 }
1505
1506 static noinline_for_stack int scrub_supers(struct scrub_dev *sdev)
1507 {
1508         int     i;
1509         u64     bytenr;
1510         u64     gen;
1511         int     ret;
1512         struct btrfs_device *device = sdev->dev;
1513         struct btrfs_root *root = device->dev_root;
1514
1515         gen = root->fs_info->last_trans_committed;
1516
1517         for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
1518                 bytenr = btrfs_sb_offset(i);
1519                 if (bytenr + BTRFS_SUPER_INFO_SIZE >= device->total_bytes)
1520                         break;
1521
1522                 ret = scrub_page(sdev, bytenr, PAGE_SIZE, bytenr,
1523                                  BTRFS_EXTENT_FLAG_SUPER, gen, i, NULL, 1);
1524                 if (ret)
1525                         return ret;
1526         }
1527         wait_event(sdev->list_wait, atomic_read(&sdev->in_flight) == 0);
1528
1529         return 0;
1530 }
1531
1532 /*
1533  * get a reference count on fs_info->scrub_workers. start worker if necessary
1534  */
1535 static noinline_for_stack int scrub_workers_get(struct btrfs_root *root)
1536 {
1537         struct btrfs_fs_info *fs_info = root->fs_info;
1538
1539         mutex_lock(&fs_info->scrub_lock);
1540         if (fs_info->scrub_workers_refcnt == 0) {
1541                 btrfs_init_workers(&fs_info->scrub_workers, "scrub",
1542                            fs_info->thread_pool_size, &fs_info->generic_worker);
1543                 fs_info->scrub_workers.idle_thresh = 4;
1544                 btrfs_start_workers(&fs_info->scrub_workers, 1);
1545         }
1546         ++fs_info->scrub_workers_refcnt;
1547         mutex_unlock(&fs_info->scrub_lock);
1548
1549         return 0;
1550 }
1551
1552 static noinline_for_stack void scrub_workers_put(struct btrfs_root *root)
1553 {
1554         struct btrfs_fs_info *fs_info = root->fs_info;
1555
1556         mutex_lock(&fs_info->scrub_lock);
1557         if (--fs_info->scrub_workers_refcnt == 0)
1558                 btrfs_stop_workers(&fs_info->scrub_workers);
1559         WARN_ON(fs_info->scrub_workers_refcnt < 0);
1560         mutex_unlock(&fs_info->scrub_lock);
1561 }
1562
1563
1564 int btrfs_scrub_dev(struct btrfs_root *root, u64 devid, u64 start, u64 end,
1565                     struct btrfs_scrub_progress *progress, int readonly)
1566 {
1567         struct scrub_dev *sdev;
1568         struct btrfs_fs_info *fs_info = root->fs_info;
1569         int ret;
1570         struct btrfs_device *dev;
1571
1572         if (btrfs_fs_closing(root->fs_info))
1573                 return -EINVAL;
1574
1575         /*
1576          * check some assumptions
1577          */
1578         if (root->sectorsize != PAGE_SIZE ||
1579             root->sectorsize != root->leafsize ||
1580             root->sectorsize != root->nodesize) {
1581                 printk(KERN_ERR "btrfs_scrub: size assumptions fail\n");
1582                 return -EINVAL;
1583         }
1584
1585         ret = scrub_workers_get(root);
1586         if (ret)
1587                 return ret;
1588
1589         mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
1590         dev = btrfs_find_device(root, devid, NULL, NULL);
1591         if (!dev || dev->missing) {
1592                 mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1593                 scrub_workers_put(root);
1594                 return -ENODEV;
1595         }
1596         mutex_lock(&fs_info->scrub_lock);
1597
1598         if (!dev->in_fs_metadata) {
1599                 mutex_unlock(&fs_info->scrub_lock);
1600                 mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1601                 scrub_workers_put(root);
1602                 return -ENODEV;
1603         }
1604
1605         if (dev->scrub_device) {
1606                 mutex_unlock(&fs_info->scrub_lock);
1607                 mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1608                 scrub_workers_put(root);
1609                 return -EINPROGRESS;
1610         }
1611         sdev = scrub_setup_dev(dev);
1612         if (IS_ERR(sdev)) {
1613                 mutex_unlock(&fs_info->scrub_lock);
1614                 mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1615                 scrub_workers_put(root);
1616                 return PTR_ERR(sdev);
1617         }
1618         sdev->readonly = readonly;
1619         dev->scrub_device = sdev;
1620
1621         atomic_inc(&fs_info->scrubs_running);
1622         mutex_unlock(&fs_info->scrub_lock);
1623         mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1624
1625         down_read(&fs_info->scrub_super_lock);
1626         ret = scrub_supers(sdev);
1627         up_read(&fs_info->scrub_super_lock);
1628
1629         if (!ret)
1630                 ret = scrub_enumerate_chunks(sdev, start, end);
1631
1632         wait_event(sdev->list_wait, atomic_read(&sdev->in_flight) == 0);
1633         atomic_dec(&fs_info->scrubs_running);
1634         wake_up(&fs_info->scrub_pause_wait);
1635
1636         wait_event(sdev->list_wait, atomic_read(&sdev->fixup_cnt) == 0);
1637
1638         if (progress)
1639                 memcpy(progress, &sdev->stat, sizeof(*progress));
1640
1641         mutex_lock(&fs_info->scrub_lock);
1642         dev->scrub_device = NULL;
1643         mutex_unlock(&fs_info->scrub_lock);
1644
1645         scrub_free_dev(sdev);
1646         scrub_workers_put(root);
1647
1648         return ret;
1649 }
1650
1651 int btrfs_scrub_pause(struct btrfs_root *root)
1652 {
1653         struct btrfs_fs_info *fs_info = root->fs_info;
1654
1655         mutex_lock(&fs_info->scrub_lock);
1656         atomic_inc(&fs_info->scrub_pause_req);
1657         while (atomic_read(&fs_info->scrubs_paused) !=
1658                atomic_read(&fs_info->scrubs_running)) {
1659                 mutex_unlock(&fs_info->scrub_lock);
1660                 wait_event(fs_info->scrub_pause_wait,
1661                            atomic_read(&fs_info->scrubs_paused) ==
1662                            atomic_read(&fs_info->scrubs_running));
1663                 mutex_lock(&fs_info->scrub_lock);
1664         }
1665         mutex_unlock(&fs_info->scrub_lock);
1666
1667         return 0;
1668 }
1669
1670 int btrfs_scrub_continue(struct btrfs_root *root)
1671 {
1672         struct btrfs_fs_info *fs_info = root->fs_info;
1673
1674         atomic_dec(&fs_info->scrub_pause_req);
1675         wake_up(&fs_info->scrub_pause_wait);
1676         return 0;
1677 }
1678
1679 int btrfs_scrub_pause_super(struct btrfs_root *root)
1680 {
1681         down_write(&root->fs_info->scrub_super_lock);
1682         return 0;
1683 }
1684
1685 int btrfs_scrub_continue_super(struct btrfs_root *root)
1686 {
1687         up_write(&root->fs_info->scrub_super_lock);
1688         return 0;
1689 }
1690
1691 int btrfs_scrub_cancel(struct btrfs_root *root)
1692 {
1693         struct btrfs_fs_info *fs_info = root->fs_info;
1694
1695         mutex_lock(&fs_info->scrub_lock);
1696         if (!atomic_read(&fs_info->scrubs_running)) {
1697                 mutex_unlock(&fs_info->scrub_lock);
1698                 return -ENOTCONN;
1699         }
1700
1701         atomic_inc(&fs_info->scrub_cancel_req);
1702         while (atomic_read(&fs_info->scrubs_running)) {
1703                 mutex_unlock(&fs_info->scrub_lock);
1704                 wait_event(fs_info->scrub_pause_wait,
1705                            atomic_read(&fs_info->scrubs_running) == 0);
1706                 mutex_lock(&fs_info->scrub_lock);
1707         }
1708         atomic_dec(&fs_info->scrub_cancel_req);
1709         mutex_unlock(&fs_info->scrub_lock);
1710
1711         return 0;
1712 }
1713
1714 int btrfs_scrub_cancel_dev(struct btrfs_root *root, struct btrfs_device *dev)
1715 {
1716         struct btrfs_fs_info *fs_info = root->fs_info;
1717         struct scrub_dev *sdev;
1718
1719         mutex_lock(&fs_info->scrub_lock);
1720         sdev = dev->scrub_device;
1721         if (!sdev) {
1722                 mutex_unlock(&fs_info->scrub_lock);
1723                 return -ENOTCONN;
1724         }
1725         atomic_inc(&sdev->cancel_req);
1726         while (dev->scrub_device) {
1727                 mutex_unlock(&fs_info->scrub_lock);
1728                 wait_event(fs_info->scrub_pause_wait,
1729                            dev->scrub_device == NULL);
1730                 mutex_lock(&fs_info->scrub_lock);
1731         }
1732         mutex_unlock(&fs_info->scrub_lock);
1733
1734         return 0;
1735 }
1736 int btrfs_scrub_cancel_devid(struct btrfs_root *root, u64 devid)
1737 {
1738         struct btrfs_fs_info *fs_info = root->fs_info;
1739         struct btrfs_device *dev;
1740         int ret;
1741
1742         /*
1743          * we have to hold the device_list_mutex here so the device
1744          * does not go away in cancel_dev. FIXME: find a better solution
1745          */
1746         mutex_lock(&fs_info->fs_devices->device_list_mutex);
1747         dev = btrfs_find_device(root, devid, NULL, NULL);
1748         if (!dev) {
1749                 mutex_unlock(&fs_info->fs_devices->device_list_mutex);
1750                 return -ENODEV;
1751         }
1752         ret = btrfs_scrub_cancel_dev(root, dev);
1753         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
1754
1755         return ret;
1756 }
1757
1758 int btrfs_scrub_progress(struct btrfs_root *root, u64 devid,
1759                          struct btrfs_scrub_progress *progress)
1760 {
1761         struct btrfs_device *dev;
1762         struct scrub_dev *sdev = NULL;
1763
1764         mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
1765         dev = btrfs_find_device(root, devid, NULL, NULL);
1766         if (dev)
1767                 sdev = dev->scrub_device;
1768         if (sdev)
1769                 memcpy(progress, &sdev->stat, sizeof(*progress));
1770         mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
1771
1772         return dev ? (sdev ? 0 : -ENOTCONN) : -ENODEV;
1773 }