Balance cannot be started on a read-only filesystem and will have to finish/exit before eg. going to read-only via remount.
In case the filesystem is forcibly set to read-only after an error, balance will finish anyway and if the cancel call is too fast it will just wait for that to happen. The last case is when the balance is paused after mount but it's read-only and cancelling would want to delete the item. The test is moved after the check if balance is running at all, as it looks more logical to report "no balance running" instead of "read-only filesystem". Signed-off-by: David Sterba <[email protected]> --- fs/btrfs/volumes.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index a766d2f988c1..9e48a4654d3a 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -4053,15 +4053,20 @@ int btrfs_pause_balance(struct btrfs_fs_info *fs_info) int btrfs_cancel_balance(struct btrfs_fs_info *fs_info) { - if (sb_rdonly(fs_info->sb)) - return -EROFS; - mutex_lock(&fs_info->balance_mutex); if (!fs_info->balance_ctl) { mutex_unlock(&fs_info->balance_mutex); return -ENOTCONN; } + /* + * A paused balance with the item stored on disk can be resumed at + * mount time if the mount is read-write. Otherwise it's still paused + * and we must not allow cancelling as it deletes the item. + */ + if (sb_rdonly(fs_info->sb)) + return -EROFS; + atomic_inc(&fs_info->balance_cancel_req); /* * if we are running just wait and return, balance item is -- 2.16.2 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
