Delay in WRITE delegation recall during COMMIT

[Ajay Gulati]

Hi  Bruce,
     I am assuming you meant filp (struct file *), when you mentioned
filehandle. I was wondering if it would be hard to  not use nfsd_open()
during nfsd_commit()?
I modified nfsd_commit() to use dentry_open() instead of nfsd_open(). The
same thing as write wasn't possible currently because nfsd4_write has
stateid which makes it easy to get filp. The "COMMIT" only has offset and
count.

I am attaching the patch below, which seems to work. I modified __setlease()
also to get write delegation and test the patch. I am looking into making
delegations work without the modification in __setlease(), if you have any
ideas on that please let me know.

 nfsd-spec/vfs.c |   25 +++++++++++++++----------
 1 files changed, 15 insertions(+), 10 deletions(-)

diff -puN vfs.c~commit-breaklease vfs.c
--- nfsd/vfs.c~commit-breaklease        2006-08-18 14:31:13.000000000 -0700
+++ nfsd-spec/vfs.c     2006-08-18 14:31:55.000000000 -0700
@@ -1052,22 +1052,27 @@ nfsd_commit(struct svc_rqst *rqstp, stru
                loff_t offset, unsigned long count)
 {
        struct file     *file;
-       int             err;
+       int             err = nfs_ok;

        if ((u64)count > ~(u64)offset)
                return nfserr_inval;
+       if (!EX_ISSYNC(fhp->fh_export))
+               return nfs_ok;

-       if ((err = nfsd_open(rqstp, fhp, S_IFREG, MAY_WRITE, &file)) != 0)
+       err = nfsd_permission(fhp->fh_export, fhp->fh_dentry,
+                               MAY_WRITE|MAY_OWNER_OVERRIDE);
+       if (err)
                return err;
-       if (EX_ISSYNC(fhp->fh_export)) {
-               if (file->f_op && file->f_op->fsync) {
-                       err = nfserrno(nfsd_sync(file));
-               } else {
-                       err = nfserr_notsupp;
-               }
-       }
+       file = dentry_open(dget(fhp->fh_dentry),
mntget(fhp->fh_export->ex_mnt),
+                               O_WRONLY | O_LARGEFILE);
+       if (IS_ERR(file))
+               return nfserrno(PTR_ERR(file));
+       if (file->f_op && file->f_op->fsync)
+               err = nfserrno(nfsd_sync(file));
+       else
+               err = nfserr_notsupp;

-       nfsd_close(file);
+       fput(file);
        return err;
 }
 #endif /* CONFIG_NFSD_V3 */


Thanks for your comments and suggestions.
-Ajay

On 8/18/06, J. Bruce Fields <bfields at fieldses.org> wrote:
>
> On Fri, Aug 18, 2006 at 12:09:53PM -0500, Ajay Gulati wrote:
> > Hi Bruce,
> > You are right, the linux kernel doesn't give out write delegations. I
> > had been playing with write delegations and had
> > modified the code in __setlease() to make it work. I thought I had
> removed
> > that patch for my current testing but when you mentioned it, I went back
> > and checked again just to find that it was compiled in by mistake. Here
> is
> > the change in __setlease() (fs/locks.c) that caused write delegation to
> > be granted.
> >
> > if ((arg == F_WRLCK)
> >           && ((atomic_read(&dentry->d_count) > 2)
> >               || (atomic_read(&inode->i_count) > 2)))
> >               goto out;
>
> Sounds like some more changes are needed to get write delegations
> working properly.  To handle this particular problem, maybe
> nfsd_commit() needs to have the option of taking a filehandle (as does
> nfsd_write() now, for example) so that it doesn't have to do a new open?
> I'm not sure.
>
> --b.
>
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