NFSv4 do not send an empty SETATTR compound

Commit 536e43d12b9517bbbf6114cd1a12be27857a4d7a ATTR_OPEN check can result in
an ia_valid with only ATTR_FILE set, and no NFS_VALID_ATTRS attributes to
request from the server.

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

1 files changed, 8 insertions, 4 deletions

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index f23977e4ac0f..15fc7e4664ed 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -2549,6 +2549,14 @@ nfs4_proc_setattr(struct dentry *dentry, struct nfs_fattr *fattr,
 
         nfs_fattr_init(fattr);
         
+        /* Deal with open(O_TRUNC) */
+        if (sattr->ia_valid & ATTR_OPEN)
+                sattr->ia_valid &= ~(ATTR_MTIME|ATTR_CTIME|ATTR_OPEN);
+
+        /* Optimization: if the end result is no change, don't RPC */
+        if ((sattr->ia_valid & ~(ATTR_FILE)) == 0)
+                return 0;
+
         /* Search for an existing open(O_WRITE) file */
         if (sattr->ia_valid & ATTR_FILE) {
                 struct nfs_open_context *ctx;
@@ -2560,10 +2568,6 @@ nfs4_proc_setattr(struct dentry *dentry, struct nfs_fattr *fattr,
                 }
         }
 
-        /* Deal with open(O_TRUNC) */
-        if (sattr->ia_valid & ATTR_OPEN)
-                sattr->ia_valid &= ~(ATTR_MTIME|ATTR_CTIME|ATTR_OPEN);
-
         status = nfs4_do_setattr(inode, cred, fattr, sattr, state);
         if (status == 0)
                 nfs_setattr_update_inode(inode, sattr);