From 7cb2c4202ed5730ecbf13c5d34c2cadff4cbe88f Mon Sep 17 00:00:00 2001 From: Omar Sandoval Date: Fri, 19 Jun 2015 11:52:49 -0700 Subject: [PATCH] Btrfs: count devices correctly in readahead during RAID 5/6 replace Commit 5fbc7c59fd22 ("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 2c8cdd6ee4e7 ("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 Signed-off-by: Chris Mason --- fs/btrfs/reada.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/reada.c b/fs/btrfs/reada.c index 0e7beea92b4c..4645cd16d5ba 100644 --- a/fs/btrfs/reada.c +++ b/fs/btrfs/reada.c @@ -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;