From: "Benjamin Coddington" <bcodding@redhat.com>
To: trond.myklebust@hammerspace.com, anna.schumaker@netapp.com
Cc: linux-nfs@vger.kernel.org
Subject: Re: [PATCH v2] NFS: Don't skip lookup when holding a delegation
Date: Thu, 16 Jan 2020 10:19:06 -0500 [thread overview]
Message-ID: <6399DBA2-DA9D-40C3-80BC-6DCE94BB9C49@redhat.com> (raw)
In-Reply-To: <77be993185fa7f114f6856f74f2f7affb5bd411d.1568904510.git.bcodding@redhat.com>
I'd like to bump this one again while we're talking about
lookup/revalidation.
We have folks that hit this problem in the field:
- client caches a dentry
- file gets moved
- server gives out a delegation
- client never notices the change because we always skip
revalidation
Is this the wrong place to fix this? Any other feedback?
Ben
On 19 Sep 2019, at 10:49, Benjamin Coddington wrote:
> If we skip lookup revalidation while holding a delegation, we might
> miss
> that the file has changed directories on the server. The directory's
> change attribute should still be checked against the dentry's d_time
> to
> perform a complete revalidation.
>
> V2 - Add some commentary as suggested-by J. Bruce Fields.
>
> Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
> ---
> fs/nfs/dir.c | 17 +++++++++++------
> 1 file changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
> index 0adfd8840110..8723e82f5c9d 100644
> --- a/fs/nfs/dir.c
> +++ b/fs/nfs/dir.c
> @@ -1197,12 +1197,20 @@ nfs_do_lookup_revalidate(struct inode *dir,
> struct dentry *dentry,
> goto out_bad;
> }
>
> - if (NFS_PROTO(dir)->have_delegation(inode, FMODE_READ))
> - return nfs_lookup_revalidate_delegated(dir, dentry, inode);
> -
> /* Force a full look up iff the parent directory has changed */
> if (!(flags & (LOOKUP_EXCL | LOOKUP_REVAL)) &&
> nfs_check_verifier(dir, dentry, flags & LOOKUP_RCU)) {
> +
> + /*
> + * Note that the file can't move while we hold a
> + * delegation. But this dentry could have been cached
> + * before we got a delegation. So it's only safe to
> + * skip revalidation when the parent directory is
> + * unchanged:
> + */
> + if (NFS_PROTO(dir)->have_delegation(inode, FMODE_READ))
> + return nfs_lookup_revalidate_delegated(dir, dentry, inode);
> +
> error = nfs_lookup_verify_inode(inode, flags);
> if (error) {
> if (error == -ESTALE)
> @@ -1635,9 +1643,6 @@ nfs4_do_lookup_revalidate(struct inode *dir,
> struct dentry *dentry,
> if (inode == NULL)
> goto full_reval;
>
> - if (NFS_PROTO(dir)->have_delegation(inode, FMODE_READ))
> - return nfs_lookup_revalidate_delegated(dir, dentry, inode);
> -
> /* NFS only supports OPEN on regular files */
> if (!S_ISREG(inode->i_mode))
> goto full_reval;
> --
> 2.20.1
next prev parent reply other threads:[~2020-01-16 15:19 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-19 14:49 [PATCH v2] NFS: Don't skip lookup when holding a delegation Benjamin Coddington
2020-01-16 15:19 ` Benjamin Coddington [this message]
2020-01-16 16:02 ` Trond Myklebust
2020-01-16 16:32 ` Benjamin Coddington
2020-01-16 16:44 ` Trond Myklebust
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