stop using igrab in xfs_vn_link

->link is guranteed to get an already reference inode passed so we
can do a simple increment of i_count instead of using igrab and thus
avoid banging on the global inode_lock.  This is what most filesystems
already do.

Also move the increment after the call to xfs_link to simplify error
handling.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Niv Sardi <xaiki@sgi.com>

fs/xfs/linux-2.6/xfs_iops.c

@@ -367,21 +367,18 @@ xfs_vn_link(
 	struct inode	*dir,
 	struct dentry	*dentry)
 {
-	struct inode	*inode;	/* inode of guy being linked to */
+	struct inode	*inode = old_dentry->d_inode;
 	struct xfs_name	name;
 	int		error;
 
-	inode = old_dentry->d_inode;
 	xfs_dentry_to_name(&name, dentry);
 
-	igrab(inode);
 	error = xfs_link(XFS_I(dir), XFS_I(inode), &name);
-	if (unlikely(error)) {
-		iput(inode);
+	if (unlikely(error))
 		return -error;
-	}
 
 	xfs_iflags_set(XFS_I(dir), XFS_IMODIFIED);
+	atomic_inc(&inode->i_count);
 	d_instantiate(dentry, inode);
 	return 0;
 }