4.18-stable review patch. If anyone has any objections, please let me know.
------------------ From: David Sterba <[email protected]> [ Upstream commit f5194e34cabaddd348a90f950e0a8188dd26cdc0 ] Prepartory work to fix race between mount and device scan. The callers will have to manage the critical section, eg. mount wants to scan and then call btrfs_open_devices without the ioctl scan walking in and modifying the fs devices in the meantime. Reviewed-by: Anand Jain <[email protected]> Signed-off-by: David Sterba <[email protected]> Signed-off-by: Sasha Levin <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- fs/btrfs/super.c | 2 ++ fs/btrfs/volumes.c | 4 ++-- 2 files changed, 4 insertions(+), 2 deletions(-) --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -1565,7 +1565,9 @@ static struct dentry *btrfs_mount_root(s goto error_fs_info; } + mutex_lock(&uuid_mutex); error = btrfs_open_devices(fs_devices, mode, fs_type); + mutex_unlock(&uuid_mutex); if (error) goto error_fs_info; --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -1146,7 +1146,8 @@ int btrfs_open_devices(struct btrfs_fs_d { int ret; - mutex_lock(&uuid_mutex); + lockdep_assert_held(&uuid_mutex); + mutex_lock(&fs_devices->device_list_mutex); if (fs_devices->opened) { fs_devices->opened++; @@ -1156,7 +1157,6 @@ int btrfs_open_devices(struct btrfs_fs_d ret = open_fs_devices(fs_devices, flags, holder); } mutex_unlock(&fs_devices->device_list_mutex); - mutex_unlock(&uuid_mutex); return ret; }
