diff options
| author | Li Zefan <lizf@cn.fujitsu.com> | 2011-12-07 11:38:24 +0800 |
|---|---|---|
| committer | Li Zefan <lizf@cn.fujitsu.com> | 2012-01-11 10:26:54 +0800 |
| commit | b367e47fb3a70f5d24ebd6faf7d42436d485fb2d (patch) | |
| tree | 5acc05bae14070f2dad3433a1482fe3a7bab0744 | |
| parent | c7c144db531fda414e532adac56e965ce332e2a5 (diff) | |
Btrfs: fix possible deadlock when opening a seed device
The correct lock order is uuid_mutex -> volume_mutex -> chunk_mutex,
but when we mount a filesystem which has backing seed devices, we have
this lock chain:
open_ctree()
lock(chunk_mutex);
read_chunk_tree();
read_one_dev();
open_seed_devices();
lock(uuid_mutex);
and then we hit a lockdep splat.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
| -rw-r--r-- | fs/btrfs/disk-io.c | 2 | ||||
| -rw-r--r-- | fs/btrfs/volumes.c | 9 |
2 files changed, 7 insertions, 4 deletions
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 3f9d5551e58..858ab347413 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -2270,9 +2270,7 @@ struct btrfs_root *open_ctree(struct super_block *sb, (unsigned long)btrfs_header_chunk_tree_uuid(chunk_root->node), BTRFS_UUID_SIZE); - mutex_lock(&fs_info->chunk_mutex); ret = btrfs_read_chunk_tree(chunk_root); - mutex_unlock(&fs_info->chunk_mutex); if (ret) { printk(KERN_WARNING "btrfs: failed to read chunk tree on %s\n", sb->s_id); diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 563ef650850..fbb493b28d5 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -3506,7 +3506,7 @@ static int open_seed_devices(struct btrfs_root *root, u8 *fsid) struct btrfs_fs_devices *fs_devices; int ret; - mutex_lock(&uuid_mutex); + BUG_ON(!mutex_is_locked(&uuid_mutex)); fs_devices = root->fs_info->fs_devices->seed; while (fs_devices) { @@ -3544,7 +3544,6 @@ static int open_seed_devices(struct btrfs_root *root, u8 *fsid) fs_devices->seed = root->fs_info->fs_devices->seed; root->fs_info->fs_devices->seed = fs_devices; out: - mutex_unlock(&uuid_mutex); return ret; } @@ -3687,6 +3686,9 @@ int btrfs_read_chunk_tree(struct btrfs_root *root) if (!path) return -ENOMEM; + mutex_lock(&uuid_mutex); + lock_chunks(root); + /* first we search for all of the device items, and then we * read in all of the chunk items. This way we can create chunk * mappings that reference all of the devices that are afound @@ -3737,6 +3739,9 @@ again: } ret = 0; error: + unlock_chunks(root); + mutex_unlock(&uuid_mutex); + btrfs_free_path(path); return ret; } |