On Fri, May 05, 2017 at 10:53:27AM +0200, Jan Kara wrote:
> Quota files have special ranking of i_data_sem lock. We inform lockdep
> about it when turning on quotas however when turning quotas off, we
> don't clear the lockdep subclass from i_data_sem lock and thus when the
> inode gets later reused for a normal file or directory, lockdep gets
> confused and complains about possible deadlocks. Fix the problem by
> resetting lockdep subclass of i_data_sem on quota off.
>
> Reported-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
> Signed-off-by: Jan Kara <jack@xxxxxxx>
Yep, this fixes the lockdep warning for me, thanks!
Tested-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
> ---
> fs/ext4/super.c | 14 +++++---------
> 1 file changed, 5 insertions(+), 9 deletions(-)
>
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index a9c72e39a4ee..77043dc7f704 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -846,14 +846,9 @@ static inline void ext4_quota_off_umount(struct super_block *sb)
> {
> int type;
>
> - if (ext4_has_feature_quota(sb)) {
> - dquot_disable(sb, -1,
> - DQUOT_USAGE_ENABLED | DQUOT_LIMITS_ENABLED);
> - } else {
> - /* Use our quota_off function to clear inode flags etc. */
> - for (type = 0; type < EXT4_MAXQUOTAS; type++)
> - ext4_quota_off(sb, type);
> - }
> + /* Use our quota_off function to clear inode flags etc. */
> + for (type = 0; type < EXT4_MAXQUOTAS; type++)
> + ext4_quota_off(sb, type);
> }
> #else
> static inline void ext4_quota_off_umount(struct super_block *sb)
> @@ -5476,7 +5471,7 @@ static int ext4_quota_off(struct super_block *sb, int type)
> goto out;
>
> err = dquot_quota_off(sb, type);
> - if (err)
> + if (err || ext4_has_feature_quota(sb))
> goto out_put;
>
> inode_lock(inode);
> @@ -5496,6 +5491,7 @@ static int ext4_quota_off(struct super_block *sb, int type)
> out_unlock:
> inode_unlock(inode);
> out_put:
> + lockdep_set_quota_inode(inode, I_DATA_SEM_NORMAL);
> iput(inode);
> return err;
> out:
> --
> 2.12.0
>
