Re: [PATCH 4/4] reiserfs: fix journal device opening

[Jan Kara <jack@suse.cz>]

On Mon 09-10-23 14:33:41, Christian Brauner wrote:
> We can't open devices with s_umount held without risking deadlocks.
> So drop s_umount and reacquire it when opening the journal device.
> 
> Reported-by: syzbot+062317ea1d0a6d5e29e7@syzkaller.appspotmail.com
> Signed-off-by: Christian Brauner <brauner@kernel.org>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  fs/reiserfs/journal.c | 22 ++++++++++++++++------
>  1 file changed, 16 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/reiserfs/journal.c b/fs/reiserfs/journal.c
> index e001a96fc76c..0c680de72d43 100644
> --- a/fs/reiserfs/journal.c
> +++ b/fs/reiserfs/journal.c
> @@ -2714,7 +2714,7 @@ int journal_init(struct super_block *sb, const char *j_dev_name,
>  	struct reiserfs_journal_header *jh;
>  	struct reiserfs_journal *journal;
>  	struct reiserfs_journal_list *jl;
> -	int ret;
> +	int ret = 1;
>  
>  	journal = SB_JOURNAL(sb) = vzalloc(sizeof(struct reiserfs_journal));
>  	if (!journal) {
> @@ -2727,6 +2727,13 @@ int journal_init(struct super_block *sb, const char *j_dev_name,
>  	INIT_LIST_HEAD(&journal->j_working_list);
>  	INIT_LIST_HEAD(&journal->j_journal_list);
>  	journal->j_persistent_trans = 0;
> +
> +	/*
> +	 * blkdev_put() can't be called under s_umount, see the comment
> +	 * in get_tree_bdev() for more details
> +	 */
> +	up_write(&sb->s_umount);
> +
>  	if (reiserfs_allocate_list_bitmaps(sb, journal->j_list_bitmap,
>  					   reiserfs_bmap_count(sb)))
>  		goto free_and_return;
> @@ -2891,8 +2898,7 @@ int journal_init(struct super_block *sb, const char *j_dev_name,
>  		goto free_and_return;
>  	}
>  
> -	ret = journal_read(sb);
> -	if (ret < 0) {
> +	if (journal_read(sb) < 0) {
>  		reiserfs_warning(sb, "reiserfs-2006",
>  				 "Replay Failure, unable to mount");
>  		goto free_and_return;
> @@ -2900,10 +2906,14 @@ int journal_init(struct super_block *sb, const char *j_dev_name,
>  
>  	INIT_DELAYED_WORK(&journal->j_work, flush_async_commits);
>  	journal->j_work_sb = sb;
> -	return 0;
> +	ret = 0;
> +
>  free_and_return:
> -	free_journal_ram(sb);
> -	return 1;
> +	if (ret)
> +		free_journal_ram(sb);
> +
> +	down_write(&sb->s_umount);
> +	return ret;
>  }
>  
>  /*
> 
> -- 
> 2.34.1
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR