Re: [PATCH 2/5] fs: make ustat() and quotactl() killable in lookup

[Jan Kara]

On Wed 21-10-26 16:46:58, Josef Bacik wrote:
> user_get_super() looks up the superblock for a device number on behalf of
> ustat(2) and quotactl(2).  If that superblock is still being mounted it
> waits for SB_BORN, and then for s_umount, in super_lock().  With a mount
> which is stuck on its device neither system call ever returns, and neither
> can be killed.
> 
> Both fail if there is no superblock for the device, which is what
> user_get_super() returning NULL means to them.  Use super_lock_killable()
> and return NULL when the task is killed.
> 
> Signed-off-by: Josef Bacik <josef@xxxxxxxxxxxxxx>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@xxxxxxx>

								Honza

> ---
>  fs/super.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/super.c b/fs/super.c
> index 7164c92fe70e..40f92ffa39c1 100644
> --- a/fs/super.c
> +++ b/fs/super.c
> @@ -1172,9 +1172,15 @@ struct super_block *user_get_super(dev_t dev, bool excl)
>  
>  	for (sb_dev = super_dev_first(dev); sb_dev; sb_dev = super_dev_next(sb_dev)) {
>  		struct super_block *sb = sb_dev->sd_sb;
> +		int ret;
>  
> -		if (!super_lock(sb, excl))
> +		ret = super_lock_killable(sb, excl);
> +		if (ret == -ENOENT)
>  			continue;
> +		if (ret) {
> +			super_dev_put(sb_dev);
> +			return NULL;
> +		}
>  
>  		/* The pinned entry holds a passive reference, take our own. */
>  		refcount_inc(&sb->s_passive);
> 
> -- 
> 2.55.0
> 
-- 
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR