On Tue, May 21, 2013 at 03:23:38PM -0400, bfields wrote:
> On Wed, May 15, 2013 at 02:51:49PM -0400, Steve Dickson wrote:
> > When an exclusive create is done with the mode bits
> > set (aka open(testfile, O_CREAT | O_EXCL, 0777)) this
>
> so implicitly O_RDONLY. Is that common? Maybe so, OK.
>
> > causes a OPEN op followed by a SETATTR op. When a
> > read delegation is given in the OPEN, it causes
> > the SETATTR to delay with EAGAIN until the
> > delegation is recalled.
> >
> > This patch caused exclusive creates to give out
> > a write delegation (which turn into no delegation)
> > which allows the SETATTR seamlessly succeed.
>
> OK. May as well make it apply to all creates, though, I think?
> Any create flag seems like a sign the file's likely to be modified soon,
> hence isn't a good candidate for a read delegation.
That would look like the following.
--b.
commit 3f47b6220ca6b08a7ab86baaaab87389707a3308
Author: Steve Dickson <steved@xxxxxxxxxx>
Date: Wed May 15 14:51:49 2013 -0400
NFSD: Don't give out read delegations on exclusive creates
When an exclusive create is done with the mode bits
set (aka open(testfile, O_CREAT | O_EXCL, 0777)) this
causes a OPEN op followed by a SETATTR op. When a
read delegation is given in the OPEN, it causes
the SETATTR to delay with EAGAIN until the
delegation is recalled.
This patch caused exclusive creates to give out
a write delegation (which turn into no delegation)
which allows the SETATTR seamlessly succeed.
Signed-off-by: Steve Dickson <steved@xxxxxxxxxx>
[bfields: do this for any CREATE, not just exclusive; comment]
Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index c4f6339..44dcea9 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -3113,8 +3113,17 @@ nfs4_open_delegation(struct net *net, struct svc_fh *fh,
goto out;
if (!cb_up || !(oo->oo_flags & NFS4_OO_CONFIRMED))
goto out;
+ /*
+ * Also, if the file was opened for write or
+ * create, there's a good chance the client's
+ * about to write to it, resulting in an
+ * immediate recall (since we don't support
+ * write delegations):
+ */
if (open->op_share_access & NFS4_SHARE_ACCESS_WRITE)
flag = NFS4_OPEN_DELEGATE_WRITE;
+ else if (open->op_create == NFS4_OPEN_CREATE)
+ flag = NFS4_OPEN_DELEGATE_WRITE;
else
flag = NFS4_OPEN_DELEGATE_READ;
break;
--
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