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From: Trond Myklebust <trondmy@hammerspace.com>
To: "chuck.lever@oracle.com" <chuck.lever@oracle.com>
Cc: "linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>
Subject: Re: [PATCH v2 1/2] nfsd: Fix a regression in nfsd_setattr()
Date: Fri, 16 Feb 2024 18:57:16 +0000	[thread overview]
Message-ID: <5c35277cd061e16a914b94e070ea6d95a75c1342.camel@hammerspace.com> (raw)
In-Reply-To: <756FABF8-FA78-4D16-A4B8-B47C4745868E@oracle.com>

On Fri, 2024-02-16 at 18:25 +0000, Chuck Lever III wrote:
> 
> 
> > On Feb 16, 2024, at 1:19 PM, Chuck Lever III
> > <chuck.lever@oracle.com> wrote:
> > 
> > 
> > 
> > > On Feb 16, 2024, at 1:18 PM, Trond Myklebust
> > > <trondmy@hammerspace.com> wrote:
> > > 
> > > On Fri, 2024-02-16 at 08:33 -0500, Chuck Lever wrote:
> > > > On Thu, Feb 15, 2024 at 08:24:50PM -0500,
> > > > trondmy@kernel.org wrote:
> > > > > From: Trond Myklebust <trond.myklebust@hammerspace.com>
> > > > > 
> > > > > Commit bb4d53d66e4b broke the NFSv3 pre/post op attributes
> > > > > behaviour
> > > > > when doing a SETATTR rpc call by stripping out the calls to
> > > > > fh_fill_pre_attrs() and fh_fill_post_attrs().
> > > > 
> > > > Can you give more detail about what broke?
> > > 
> > > Without the calls to fh_fill_pre_attrs() and
> > > fh_fill_post_attrs(), we
> > > don't store any pre/post op attributes and we can't return any
> > > such
> > > attributes to the NFSv3 client.
> > 
> > I get that. Why does that matter?
> 
> Or, to be a little less terse... clients rely on the pre/post
> op attributes around a SETATTR, I guess, but I don't see why.
> I'm missing some context.

   1. SETATTR is not atomic, and is not implemented as being atomic in
      Linux. It is perfectly possible for, say, the file to get
      truncated, but for the other attribute changes to get dropped on
      the floor. NFSv4 communicates that information via the bitmap.
      NFSv3 does it using the pre/post attributes.
   2. When doing a guarded SETATTR, if the server returns
      NFS3ERR_NOT_SYNC, the client may want to update its cached ctime
      and resend.


> 
> 
> > > > > Fixes: bb4d53d66e4b ("NFSD: use (un)lock_inode instead of
> > > > > fh_(un)lock for file operations")
> > > > > Signed-off-by: Trond Myklebust
> > > > > <trond.myklebust@hammerspace.com>
> > > > > ---
> > > > > fs/nfsd/nfs4proc.c | 4 ++++
> > > > > fs/nfsd/vfs.c      | 9 +++++++--
> > > > > 2 files changed, 11 insertions(+), 2 deletions(-)
> > > > > 
> > > > > diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> > > > > index 14712fa08f76..e6d8624efc83 100644
> > > > > --- a/fs/nfsd/nfs4proc.c
> > > > > +++ b/fs/nfsd/nfs4proc.c
> > > > > @@ -1143,6 +1143,7 @@ nfsd4_setattr(struct svc_rqst *rqstp,
> > > > > struct
> > > > > nfsd4_compound_state *cstate,
> > > > >  };
> > > > >  struct inode *inode;
> > > > >  __be32 status = nfs_ok;
> > > > > + bool save_no_wcc;
> > > > >  int err;
> > > > > 
> > > > >  if (setattr->sa_iattr.ia_valid & ATTR_SIZE) {
> > > > > @@ -1168,8 +1169,11 @@ nfsd4_setattr(struct svc_rqst *rqstp,
> > > > > struct
> > > > > nfsd4_compound_state *cstate,
> > > > > 
> > > > >  if (status)
> > > > >  goto out;
> > > > > + save_no_wcc = cstate->current_fh.fh_no_wcc;
> > > > > + cstate->current_fh.fh_no_wcc = true;
> > > > >  status = nfsd_setattr(rqstp, &cstate->current_fh, &attrs,
> > > > >  0, (time64_t)0);
> > > > > + cstate->current_fh.fh_no_wcc = save_no_wcc;
> > > > >  if (!status)
> > > > >  status = nfserrno(attrs.na_labelerr);
> > > > >  if (!status)
> > > > > diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
> > > > > index 6e7e37192461..58fab461bc00 100644
> > > > > --- a/fs/nfsd/vfs.c
> > > > > +++ b/fs/nfsd/vfs.c
> > > > > @@ -497,7 +497,7 @@ nfsd_setattr(struct svc_rqst *rqstp,
> > > > > struct
> > > > > svc_fh *fhp,
> > > > >  int accmode = NFSD_MAY_SATTR;
> > > > >  umode_t ftype = 0;
> > > > >  __be32 err;
> > > > > - int host_err;
> > > > > + int host_err = 0;
> > > > >  bool get_write_count;
> > > > >  bool size_change = (iap->ia_valid & ATTR_SIZE);
> > > > >  int retries;
> > > > > @@ -555,6 +555,9 @@ nfsd_setattr(struct svc_rqst *rqstp,
> > > > > struct
> > > > > svc_fh *fhp,
> > > > >  }
> > > > > 
> > > > >  inode_lock(inode);
> > > > > + err = fh_fill_pre_attrs(fhp);
> > > > > + if (err)
> > > > > + goto out_unlock;
> > > > >  for (retries = 1;;) {
> > > > >  struct iattr attrs;
> > > > > 
> > > > > @@ -582,13 +585,15 @@ nfsd_setattr(struct svc_rqst *rqstp,
> > > > > struct
> > > > > svc_fh *fhp,
> > > > >  attr->na_aclerr = set_posix_acl(&nop_mnt_idmap,
> > > > >  dentry,
> > > > > ACL_TYPE_DEFAULT,
> > > > >  attr->na_dpacl);
> > > > > + fh_fill_post_attrs(fhp);
> > > > > +out_unlock:
> > > > >  inode_unlock(inode);
> > > > >  if (size_change)
> > > > >  put_write_access(inode);
> > > > > out:
> > > > >  if (!host_err)
> > > > >  host_err = commit_metadata(fhp);
> > > > > - return nfserrno(host_err);
> > > > > + return err != 0 ? err : nfserrno(host_err);
> > > > > }
> > > > > 
> > > > > #if defined(CONFIG_NFSD_V4)
> > > > > -- 
> > > > > 2.43.1
> > > > > 
> > > > > 
> > > > 

-- 
Trond Myklebust Linux NFS client maintainer, Hammerspace
trond.myklebust@hammerspace.com

  reply	other threads:[~2024-02-16 18:57 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-02-16  1:24 [PATCH v2 0/2] Fix NFSv3 SETATTR behaviours trondmy
2024-02-16  1:24 ` [PATCH v2 1/2] nfsd: Fix a regression in nfsd_setattr() trondmy
2024-02-16  1:24   ` [PATCH v2 2/2] nfsd: Fix NFSv3 atomicity bugs " trondmy
2024-02-18 14:24     ` Jeff Layton
2024-02-18 22:01     ` NeilBrown
2024-02-16 13:33   ` [PATCH v2 1/2] nfsd: Fix a regression " Chuck Lever
2024-02-16 18:18     ` Trond Myklebust
2024-02-16 18:19       ` Chuck Lever III
2024-02-16 18:25         ` Chuck Lever III
2024-02-16 18:57           ` Trond Myklebust [this message]
2024-02-17 17:05             ` Chuck Lever
2024-02-17 18:16               ` Trond Myklebust
2024-02-18 14:21                 ` Jeff Layton
2024-02-18 21:57   ` NeilBrown
2024-02-19  1:33     ` Trond Myklebust
2024-02-20 15:28 ` [PATCH v2 0/2] Fix NFSv3 SETATTR behaviours Chuck Lever

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