Commit 7cb2c420 authored Jun 19, 2015 by Omar Sandoval Committed by Chris Mason Aug 09, 2015

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: Omar Sandoval <osandov@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>

parent 03679ade

fs/btrfs/reada.c

+3 −1

Original line number	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;
		u32 blocksize;
		u64 length;
		int real_stripes;
		int nzones = 0;
		int i;
		unsigned long index = logical >> PAGE_CACHE_SHIFT;
		@@ -369,7 +370,8 @@ static struct reada_extent reada_find_extent(struct btrfs_root root,
		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;

		dev = bbio->stripes[nzones].dev;

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