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Commit 7cb2c420 authored by Omar Sandoval's avatar Omar Sandoval Committed by Chris Mason
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Btrfs: count devices correctly in readahead during RAID 5/6 replace 



Commit 5fbc7c59 ("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 2c8cdd6e ("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: default avatarOmar Sandoval <osandov@fb.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
parent 03679ade

fs/btrfs/reada.c

+3 −1
Original line number Original line Diff line number Diff line
@@ -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;