linux-kernel - Re: [PATCH] cifs: fix missing unlock in cifs_file_copychunk

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Date:   Mon, 21 Nov 2022 11:42:01 -0300
From:   Paulo Alcantara <pc@....nz>
To:     ChenXiaoSong <chenxiaosong2@...wei.com>, sfrench@...ba.org,
        dhowells@...hat.com
Cc:     linux-cifs@...r.kernel.org, samba-technical@...ts.samba.org,
        linux-kernel@...r.kernel.org, chenxiaosong2@...wei.com,
        yi.zhang@...wei.com, zhangxiaoxu5@...wei.com, yanaijie@...wei.com
Subject: Re: [PATCH] cifs: fix missing unlock in cifs_file_copychunk_range()

ChenXiaoSong <chenxiaosong2@...wei.com> writes:

> xfstests generic/013 and generic/476 reported WARNING as follows:
>
>   WARNING: lock held when returning to user space!
>   6.1.0-rc5+ #4 Not tainted
>   ------------------------------------------------
>   fsstress/504233 is leaving the kernel with locks still held!
>   2 locks held by fsstress/504233:
>    #0: ffff888054c38850 (&sb->s_type->i_mutex_key#21){+.+.}-{3:3}, at:
>                         lock_two_nondirectories+0xcf/0xf0
>    #1: ffff8880b8fec750 (&sb->s_type->i_mutex_key#21/4){+.+.}-{3:3}, at:
>                         lock_two_nondirectories+0xb7/0xf0
>
> This will lead to deadlock and hungtask.
>
> Fix this by releasing locks when failed to write out on a file range in
> cifs_file_copychunk_range().
>
> Fixes: 3e3761f1ec7d ("smb3: use filemap_write_and_wait_range instead of filemap_write_and_wait")
> Signed-off-by: ChenXiaoSong <chenxiaosong2@...wei.com>
> ---
>  fs/cifs/cifsfs.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)

Reviewed-by: Paulo Alcantara (SUSE) <pc@....nz>