lkml.org 
[lkml]   [2017]   [May]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] ceph: check i_nlink while converting a file handle to dentry
From
Date

> On 17 May 2017, at 19:21, Luis Henriques <lhenriques@suse.com> wrote:
>
> Converting a file handle to a dentry can be done call after the inode
> unlink. This means that __fh_to_dentry() requires an extra check to
> verify the number of links is not 0.
>
> The issue can be easily reproduced using xfstest generic/426, which does
> something like:
>
> name_to_handle_at(&fh)
> echo 3 > /proc/sys/vm/drop_caches
> unlink()
> open_by_handle_at(&fh)
>
> The call to open_by_handle_at() should fail, as the file doesn't exist
> anymore.
>
> Cc: stable@vger.kernel.org
> Link: http://tracker.ceph.com/issues/19958
> Signed-off-by: Luis Henriques <lhenriques@suse.com>
> ---
> fs/ceph/export.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/fs/ceph/export.c b/fs/ceph/export.c
> index e8f11fa565c5..7df550c13d7f 100644
> --- a/fs/ceph/export.c
> +++ b/fs/ceph/export.c
> @@ -91,6 +91,10 @@ static struct dentry *__fh_to_dentry(struct super_block *sb, u64 ino)
> ceph_mdsc_put_request(req);
> if (!inode)
> return ERR_PTR(-ESTALE);
> + if (inode->i_nlink == 0) {
> + iput(inode);
> + return ERR_PTR(-ESTALE);
> + }
> }

maybe we should do this check in MDS

Regards
Yan, Zheng

>
> return d_obtain_alias(inode);

\
 
 \ /
  Last update: 2017-05-18 15:38    [W:0.064 / U:0.004 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site