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authorWang Shilong <wangsl.fnst@cn.fujitsu.com>2014-06-11 10:55:22 +0800
committerChris Mason <clm@fb.com>2014-06-13 09:52:21 -0700
commit5fbc7c59fd22c5a6531b40b0759624b680a95e52 (patch)
treedfd0fff7de04cc8250bfd1128bfac9f9ccff3601
parentcc68a8a5a4330a4bb72922d0c7a7044ae13ee692 (diff)
Btrfs: fix unfinished readahead thread for raid5/6 degraded mounting
Steps to reproduce: # mkfs.btrfs -f /dev/sd[b-f] -m raid5 -d raid5 # mkfs.ext4 /dev/sdc --->corrupt one of btrfs device # mount /dev/sdb /mnt -o degraded # btrfs scrub start -BRd /mnt This is because readahead would skip missing device, this is not true for RAID5/6, because REQ_GET_READ_MIRRORS return 1 for RAID5/6 block mapping. If expected data locates in missing device, readahead thread would not call __readahead_hook() which makes event @rc->elems=0 wait forever. Fix this problem by checking return value of btrfs_map_block(),we can only skip missing device safely if there are several mirrors. Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com> Signed-off-by: Chris Mason <clm@fb.com>
-rw-r--r--fs/btrfs/reada.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/fs/btrfs/reada.c b/fs/btrfs/reada.c
index 30947f923620..09230cf3a244 100644
--- a/fs/btrfs/reada.c
+++ b/fs/btrfs/reada.c
@@ -428,8 +428,13 @@ static struct reada_extent *reada_find_extent(struct btrfs_root *root,
continue;
}
if (!dev->bdev) {
- /* cannot read ahead on missing device */
- continue;
+ /*
+ * cannot read ahead on missing device, but for RAID5/6,
+ * REQ_GET_READ_MIRRORS return 1. So don't skip missing
+ * device for such case.
+ */
+ if (nzones > 1)
+ continue;
}
if (dev_replace_is_ongoing &&
dev == fs_info->dev_replace.tgtdev) {

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