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Btrfs: count devices correctly in readahead during RAID 5/6 replace 

Commit 5fbc7c59fd ("Btrfs: fix unfinished readahead thread for raid5/6
degraded mounting") fixed a problem where we would skip a missing device
when we shouldn't have because there are no other mirrors to read from
in RAID 5/6. After commit 2c8cdd6ee4 ("Btrfs, replace: write dirty
pages into the replace target device"), the fix doesn't work when we're
doing a missing device replace on RAID 5/6 because the replace device is
counted as a mirror so we're tricked into thinking we can safely skip
the missing device. The fix is to count only the real stripes and decide
based on that.

Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>
This commit is contained in:
Omar Sandoval 2015-06-19 11:52:49 -07:00 committed by Chris Mason
parent 03679ade86
commit 7cb2c4202e
1 changed files with 3 additions and 1 deletions
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4
fs/btrfs/reada.c
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@ -328,6 +328,7 @@ static struct reada_extent *reada_find_extent(struct btrfs_root *root,
struct btrfs_device *prev_dev; struct btrfs_device *prev_dev;
u32 blocksize; u32 blocksize;
u64 length; u64 length;
int real_stripes;
int nzones = 0; int nzones = 0;
int i; int i;
unsigned long index = logical >> PAGE_CACHE_SHIFT; unsigned long index = logical >> PAGE_CACHE_SHIFT;
@ -369,7 +370,8 @@ static struct reada_extent *reada_find_extent(struct btrfs_root *root,
goto error; goto error;
} }
for (nzones = 0; nzones < bbio->num_stripes; ++nzones) { real_stripes = bbio->num_stripes - bbio->num_tgtdevs;
for (nzones = 0; nzones < real_stripes; ++nzones) {
struct reada_zone *zone; struct reada_zone *zone;
dev = bbio->stripes[nzones].dev; dev = bbio->stripes[nzones].dev;