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authorMiao Xie <miaox@cn.fujitsu.com>2014-06-19 10:42:54 +0800
committerChris Mason <clm@fb.com>2014-06-19 14:20:56 -0700
commitc55f13964008bfea7c5bee268f28b699cbad7f00 (patch)
tree3d173761484c4fb7ed9933476a6f56e4f44c6579
parente990f16763abad35dd4d0eec791bab37c6987724 (diff)
Btrfs: fix deadlock when mounting a degraded fs
The deadlock happened when we mount degraded filesystem, the reproduced steps are following: # mkfs.btrfs -f -m raid1 -d raid1 <dev0> <dev1> # echo 1 > /sys/block/`basename <dev0>`/device/delete # mount -o degraded <dev1> <mnt> The reason was that the counter -- bi_remaining was wrong. If the missing or unwriteable device was the last device in the mapping array, we would not submit the original bio, so we shouldn't increase bi_remaining of it in btrfs_end_bio(), or we would skip the final endio handle. Fix this problem by adding a flag into btrfs bio structure. If we submit the original bio, we will set the flag, and we increase bi_remaining counter, or we don't. Though there is another way to fix it -- decrease bi_remaining counter of the original bio when we make sure the original bio is not submitted, this method need add more check and is easy to make mistake. Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Reviewed-by: Liu Bo <bo.li.liu@oracle.com> Signed-off-by: Chris Mason <clm@fb.com>
-rw-r--r--fs/btrfs/volumes.c7
-rw-r--r--fs/btrfs/volumes.h3
2 files changed, 9 insertions, 1 deletions
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 31f9036f317..4ca3c92a54b 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -5415,8 +5415,12 @@ static void btrfs_end_bio(struct bio *bio, int err)
set_bit(BIO_UPTODATE, &bio->bi_flags);
err = 0;
}
+
+ if (likely(bbio->flags & BTRFS_BIO_ORIG_BIO_SUBMITTED))
+ bio_endio_nodec(bio, err);
+ else
+ bio_endio(bio, err);
kfree(bbio);
- bio_endio_nodec(bio, err);
} else if (!is_orig_bio) {
bio_put(bio);
}
@@ -5671,6 +5675,7 @@ int btrfs_map_bio(struct btrfs_root *root, int rw, struct bio *bio,
BUG_ON(!bio); /* -ENOMEM */
} else {
bio = first_bio;
+ bbio->flags |= BTRFS_BIO_ORIG_BIO_SUBMITTED;
}
submit_stripe_bio(root, bbio, bio,
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 1a15bbeb65e..2aaa00c4781 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -190,11 +190,14 @@ struct btrfs_bio_stripe {
struct btrfs_bio;
typedef void (btrfs_bio_end_io_t) (struct btrfs_bio *bio, int err);
+#define BTRFS_BIO_ORIG_BIO_SUBMITTED 0x1
+
struct btrfs_bio {
atomic_t stripes_pending;
struct btrfs_fs_info *fs_info;
bio_end_io_t *end_io;
struct bio *orig_bio;
+ unsigned long flags;
void *private;
atomic_t error;
int max_errors;