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Message-ID: <20130827180655.GE14809@fieldses.org>
Date: Tue, 27 Aug 2013 14:06:55 -0400
From: "J. Bruce Fields" <bfields@...ldses.org>
To: Jan Kara <jack@...e.cz>
Cc: Toralf Förster <toralf.foerster@....de>,
Linux NFS mailing list <linux-nfs@...r.kernel.org>,
"user-mode-linux-devel@...ts.sourceforge.net"
<user-mode-linux-devel@...ts.sourceforge.net>,
linux-ext4@...r.kernel.org,
Linux Kernel <linux-kernel@...r.kernel.org>,
"J. Bruce Fields" <bfields@...hat.com>
Subject: Re: Issues with a rather unusual configured NFS server
On Tue, Aug 13, 2013 at 05:53:14PM -0400, bfields wrote:
> On Mon, Aug 12, 2013 at 04:36:40PM +0200, Jan Kara wrote:
> > On Sun 11-08-13 11:48:49, Toralf Förster wrote:
> > > so that the server either crashes (if it is a user mode linux image) or at least its reboot functionality got broken
> > > - if the NFS server is hammered with scary NFS calls using a fuzzy tool running at a remote NFS client under a non-privileged user id.
> > >
> > > It can re reproduced, if
> > > - the NFS share is an EXT3 or EXT4 directory
> > > - and it is created at file located at tempfs and mounted via loop device
> > > - and the NFS server is forced to umount the NFS share
> > > - and the server forced to restart the NSF service afterwards
> > > - and trinity is used
> > >
> > > I could find a scenario for an automated bisect. 2 times it brought this commit
> > > commit 68a3396178e6688ad7367202cdf0af8ed03c8727
> > > Author: J. Bruce Fields <bfields@...hat.com>
> > > Date: Thu Mar 21 11:21:50 2013 -0400
> > >
> > > nfsd4: shut down more of delegation earlier
>
> Thanks for the report. I think I see the problem--after this commit
> nfs4_set_delegation() failures result in nfs4_put_delegation being
> called, but nfs4_put_delegation doesn't free the nfs4_file that has
> already been set by alloc_init_deleg().
>
> Let me think about how to fix that....
Sorry for the slow response--can you check whether this fixes the
problem?
--b.
commit 624a0ee0375940ce4aa36330b0b5a70af6d2b6f5
Author: J. Bruce Fields <bfields@...hat.com>
Date: Thu Aug 15 16:55:26 2013 -0400
nfsd4: fix leak of inode reference on delegation failure
This fixes a regression from 68a3396178e6688ad7367202cdf0af8ed03c8727
"nfsd4: shut down more of delegation earlier".
After that commit, nfs4_set_delegation() failures result in
nfs4_put_delegation being called, but nfs4_put_delegation doesn't free
the nfs4_file that has already been set by alloc_init_deleg().
This can result in an oops on later unmounting the exported filesystem.
Note also delaying the fi_had_conflict check we're able to return a
better error (hence give 4.1 clients a better idea why the delegation
failed; though note CONFLICT isn't an exact match here, as that's
supposed to indicate a current conflict, but all we know here is that
there was one recently).
Reported-by: Toralf Förster <toralf.foerster@....de>
Signed-off-by: J. Bruce Fields <bfields@...hat.com>
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index eb9cf81..0874998 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -368,11 +368,8 @@ static struct nfs4_delegation *
alloc_init_deleg(struct nfs4_client *clp, struct nfs4_ol_stateid *stp, struct svc_fh *current_fh)
{
struct nfs4_delegation *dp;
- struct nfs4_file *fp = stp->st_file;
dprintk("NFSD alloc_init_deleg\n");
- if (fp->fi_had_conflict)
- return NULL;
if (num_delegations > max_delegations)
return NULL;
dp = delegstateid(nfs4_alloc_stid(clp, deleg_slab));
@@ -389,8 +386,7 @@ alloc_init_deleg(struct nfs4_client *clp, struct nfs4_ol_stateid *stp, struct sv
INIT_LIST_HEAD(&dp->dl_perfile);
INIT_LIST_HEAD(&dp->dl_perclnt);
INIT_LIST_HEAD(&dp->dl_recall_lru);
- get_nfs4_file(fp);
- dp->dl_file = fp;
+ dp->dl_file = NULL;
dp->dl_type = NFS4_OPEN_DELEGATE_READ;
fh_copy_shallow(&dp->dl_fh, ¤t_fh->fh_handle);
dp->dl_time = 0;
@@ -3044,22 +3040,35 @@ static int nfs4_setlease(struct nfs4_delegation *dp)
return 0;
}
-static int nfs4_set_delegation(struct nfs4_delegation *dp)
+static int nfs4_set_delegation(struct nfs4_delegation *dp, struct nfs4_file *fp)
{
- struct nfs4_file *fp = dp->dl_file;
+ int status;
- if (!fp->fi_lease)
- return nfs4_setlease(dp);
+ if (fp->fi_had_conflict)
+ return -EAGAIN;
+ get_nfs4_file(fp);
+ dp->dl_file = fp;
+ if (!fp->fi_lease) {
+ status = nfs4_setlease(dp);
+ if (status)
+ goto out_free;
+ return 0;
+ }
spin_lock(&recall_lock);
if (fp->fi_had_conflict) {
spin_unlock(&recall_lock);
- return -EAGAIN;
+ status = -EAGAIN;
+ goto out_free;
}
atomic_inc(&fp->fi_delegees);
list_add(&dp->dl_perfile, &fp->fi_delegations);
spin_unlock(&recall_lock);
list_add(&dp->dl_perclnt, &dp->dl_stid.sc_client->cl_delegations);
return 0;
+out_free:
+ put_nfs4_file(fp);
+ dp->dl_file = fp;
+ return status;
}
static void nfsd4_open_deleg_none_ext(struct nfsd4_open *open, int status)
@@ -3134,7 +3143,7 @@ nfs4_open_delegation(struct net *net, struct svc_fh *fh,
dp = alloc_init_deleg(oo->oo_owner.so_client, stp, fh);
if (dp == NULL)
goto out_no_deleg;
- status = nfs4_set_delegation(dp);
+ status = nfs4_set_delegation(dp, stp->st_file);
if (status)
goto out_free;
--
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