Re: [PATCH 0/7] Permit filesystem local caching and NFS superblock sharing [try #13]

[Trond Myklebust <trond.myklebust@fys.uio.no>]

On Tue, 2006-09-05 at 12:06 +0800, Ian Kent wrote:

> > One way to fix this is to simply not hash the dentry when we're doing
> > the O_EXCL intent optimisation, but rather to only hash it _after_ we've
> > successfully created the file on the server. Something like the attached
> > patch ought to do it.
> 
> No.
> 
> This patch simply marks the dentry negative and returns ENOMEM from the
> lookup which, as would be expected, results in this error being returned
> to userspace.

Oops. You are right. I forgot to set res=NULL...

--- Begin Message ---

• Subject: No Subject
• From: Trond Myklebust <Trond.Myklebust@netapp.com>
• Date:
• Nfs: nfs_lookup - don't hash dentry when optimising away the lookup

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
---

 fs/nfs/dir.c |   14 +++++++++++---
 1 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 51328ae..3419c2d 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -904,9 +904,15 @@ static struct dentry *nfs_lookup(struct 
 
 	lock_kernel();
 
-	/* If we're doing an exclusive create, optimize away the lookup */
-	if (nfs_is_exclusive_create(dir, nd))
-		goto no_entry;
+	/*
+	 * If we're doing an exclusive create, optimize away the lookup
+	 * but don't hash the dentry.
+	 */
+	if (nfs_is_exclusive_create(dir, nd)) {
+		d_instantiate(dentry, NULL);
+		res = NULL;
+		goto out_unlock;
+	}
 
 	error = NFS_PROTO(dir)->lookup(dir, &dentry->d_name, &fhandle, &fattr);
 	if (error == -ENOENT)
@@ -1161,6 +1167,8 @@ int nfs_instantiate(struct dentry *dentr
 	if (IS_ERR(inode))
 		return error;
 	d_instantiate(dentry, inode);
+	if (d_unhashed(dentry))
+		d_rehash(dentry);
 	return 0;
 }
 

--- End Message ---