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| author | Nikolay Borisov <nborisov@suse.com> | 2018-11-06 17:40:20 +0300 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2019-02-11 20:54:03 +0300 |
| commit | 8f20977a8f9b7d147017c49bd30a0b56ab863114 (patch) | |
| tree | c8e1a3680ac8b194ee252afb75ea52e3e443ee2a /fs/btrfs | |
| parent | f9b9919e59b245e5f6e6973f99ae57b4ef2291a0 (diff) | |
| download | linux-8f20977a8f9b7d147017c49bd30a0b56ab863114.tar.xz | |
btrfs: Always try all copies when reading extent buffers
commit f8397d69daef06d358430d3054662fb597e37c00 upstream.
When a metadata read is served the endio routine btree_readpage_end_io_hook
is called which eventually runs the tree-checker. If tree-checker fails
to validate the read eb then it sets EXTENT_BUFFER_CORRUPT flag. This
leads to btree_read_extent_buffer_pages wrongly assuming that all
available copies of this extent buffer are wrong and failing prematurely.
Fix this modify btree_read_extent_buffer_pages to read all copies of
the data.
This failure was exhibitted in xfstests btrfs/124 which would
spuriously fail its balance operations. The reason was that when balance
was run following re-introduction of the missing raid1 disk
__btrfs_map_block would map the read request to stripe 0, which
corresponded to devid 2 (the disk which is being removed in the test):
item 2 key (FIRST_CHUNK_TREE CHUNK_ITEM 3553624064) itemoff 15975 itemsize 112
length 1073741824 owner 2 stripe_len 65536 type DATA|RAID1
io_align 65536 io_width 65536 sector_size 4096
num_stripes 2 sub_stripes 1
stripe 0 devid 2 offset 2156920832
dev_uuid 8466c350-ed0c-4c3b-b17d-6379b445d5c8
stripe 1 devid 1 offset 3553624064
dev_uuid 1265d8db-5596-477e-af03-df08eb38d2ca
This caused read requests for a checksum item that to be routed to the
stale disk which triggered the aforementioned logic involving
EXTENT_BUFFER_CORRUPT flag. This then triggered cascading failures of
the balance operation.
Fixes: a826d6dcb32d ("Btrfs: check items for correctness as we search")
Suggested-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[bwh: Backported to 3.16:
- Deleted code is slightly different
- Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'fs/btrfs')
| -rw-r--r-- | fs/btrfs/disk-io.c | 10 |
1 files changed, 1 insertions, 9 deletions
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 430c27e3aa1d..64cd85a24ab8 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -430,9 +430,9 @@ static int btree_read_extent_buffer_pages(struct btrfs_root *root, int mirror_num = 0; int failed_mirror = 0; - clear_bit(EXTENT_BUFFER_CORRUPT, &eb->bflags); io_tree = &BTRFS_I(root->fs_info->btree_inode)->io_tree; while (1) { + clear_bit(EXTENT_BUFFER_CORRUPT, &eb->bflags); ret = read_extent_buffer_pages(io_tree, eb, start, WAIT_COMPLETE, btree_get_extent, mirror_num); @@ -444,14 +444,6 @@ static int btree_read_extent_buffer_pages(struct btrfs_root *root, ret = -EIO; } - /* - * This buffer's crc is fine, but its contents are corrupted, so - * there is no reason to read the other copies, they won't be - * any less wrong. - */ - if (test_bit(EXTENT_BUFFER_CORRUPT, &eb->bflags)) - break; - num_copies = btrfs_num_copies(root->fs_info, eb->start, eb->len); if (num_copies == 1) |