[Ocfs2-devel] [PATCH] ocfs2: Fix quota file corruption

[Jan Kara]

  Hello,

On Wed 19-02-14 17:56:35, Marty Sweet wrote:
> What errors do you see regarding corrupted quotas, something like below?
> kernel: [119890.305935] __quota_error: 3 callbacks suppressed
> kernel: [119890.305941] Quota error (device dm-8): find_free_dqentry:
> Data block full but it shouldn't
> kernel: [119890.306071] Quota error (device dm-8): qtree_write_dquot:
> Error -5 occurred while creating quota
> kernel: [119890.306203] (smbd,25964,2):ocfs2_acquire_dquot:817 ERROR:
> status = -5
  Yes, exactly that. I have a simple reproducer and I'm debugging the
issue so I should find the culprit soon.

								Honza
> On Wed, Feb 19, 2014 at 2:48 PM, Jan Kara <jack at suse.cz> wrote:
> > On Wed 19-02-14 14:11:02, Jan Kara wrote:
> >> Global quota files are accessed from different nodes and reading and
> >> writing of these files happens via block device page cache. Thus even
> >> though the access between nodes is properly serialized by quota file's
> >> inode lock we cannot rely on consistency of block device page cache
> >> between nodes. Indeed currently it is possible to corrupt quota files by
> >> creating and deleting quota structures from two nodes in parallel. Fix
> >> the problem by using OCFS2_BH_IGNORE_CACHE mount option when reading
> >> from quota file.
> >>
> >> CC: Goldwyn Rodrigues <rgoldwyn at suse.de>
> >> CC: Mark Fasheh <mfasheh at suse.de>
> >> Signed-off-by: Jan Kara <jack at suse.cz>
> >> ---
> >>  fs/ocfs2/quota_global.c | 3 ++-
> >>  1 file changed, 2 insertions(+), 1 deletion(-)
> >>
> >>   This is a quick fix for quota file corruption I have found during my testing
> >> (to be used for 3.13 and -stable kernels). Longer term we likely want to do
> >> something more clever. Ideally we would invalidate relevant blocks from buffer
> >> cache when node releases quota file's inode lock (similarly as we do it for
> >> page cache). I wanted to do it similarly as for e.g. extent tree blocks but
> >> I failed to find how consistency of those between nodes is achieved. Can
> >> anyone point me in the right direction? Thanks in advance.
> >   Hum, so this likely isn't the whole story because I can still see the
> > corruption. At least I've now found the metadata cache and basically
> > understand how it works so I'm now reading code around that and trying to
> > understand what screws up quota code...
> >
> >                                                                 Honza
> >
> >>
> >> diff --git a/fs/ocfs2/quota_global.c b/fs/ocfs2/quota_global.c
> >> index aaa50611ec66..f1f0cca15db6 100644
> >> --- a/fs/ocfs2/quota_global.c
> >> +++ b/fs/ocfs2/quota_global.c
> >> @@ -151,7 +151,8 @@ int ocfs2_read_quota_phys_block(struct inode *inode, u64 p_block,
> >>       int rc;
> >>
> >>       *bhp = NULL;
> >> -     rc = ocfs2_read_blocks(INODE_CACHE(inode), p_block, 1, bhp, 0,
> >> +     rc = ocfs2_read_blocks(INODE_CACHE(inode), p_block, 1, bhp,
> >> +                            OCFS2_BH_IGNORE_CACHE,
> >>                              ocfs2_validate_quota_block);
> >>       if (rc)
> >>               mlog_errno(rc);
> >> --
> >> 1.8.1.4
> >>
> > --
> > Jan Kara <jack at suse.cz>
> > SUSE Labs, CR
> >
> > _______________________________________________
> > Ocfs2-devel mailing list
> > Ocfs2-devel at oss.oracle.com
> > https://oss.oracle.com/mailman/listinfo/ocfs2-devel
> 
> 
> 
> -- 
> Marty
-- 
Jan Kara <jack at suse.cz>
SUSE Labs, CR