NFS: nfs4_lookup_revalidate: only evaluate parent if it will be used.

nfs4_lookup_revalidate only uses 'parent' to get 'dir', and only
uses 'dir' if 'inode == NULL'.

So we don't need to find out what 'parent' or 'dir' is until we
know that 'inode' is NULL.

By moving 'dget_parent' inside the 'if', we can reduce the number of
call sites for 'dput(parent)'.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

1 files changed, 8 insertions, 9 deletions

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 7dc88bb4296c..0090dae1acd3 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1529,9 +1529,7 @@ EXPORT_SYMBOL_GPL(nfs_atomic_open);
 
 static int nfs4_lookup_revalidate(struct dentry *dentry, unsigned int flags)
 {
-        struct dentry *parent = NULL;
         struct inode *inode;
-        struct inode *dir;
         int ret = 0;
 
         if (flags & LOOKUP_RCU)
@@ -1545,34 +1543,35 @@ static int nfs4_lookup_revalidate(struct dentry *dentry, unsigned int flags)
                 goto no_open;
 
         inode = dentry->d_inode;
-        parent = dget_parent(dentry);
-        dir = parent->d_inode;
 
         /* We can't create new files in nfs_open_revalidate(), so we
          * optimize away revalidation of negative dentries.
          */
         if (inode == NULL) {
+                struct dentry *parent;
+                struct inode *dir;
+
+                parent = dget_parent(dentry);
+                dir = parent->d_inode;
                 if (!nfs_neg_need_reval(dir, dentry, flags))
                         ret = 1;
+                dput(parent);
                 goto out;
         }
 
         /* NFS only supports OPEN on regular files */
         if (!S_ISREG(inode->i_mode))
-                goto no_open_dput;
+                goto no_open;
         /* We cannot do exclusive creation on a positive dentry */
         if (flags & LOOKUP_EXCL)
-                goto no_open_dput;
+                goto no_open;
 
         /* Let f_op->open() actually open (and revalidate) the file */
         ret = 1;
 
 out:
-        dput(parent);
         return ret;
 
-no_open_dput:
-        dput(parent);
 no_open:
         return nfs_lookup_revalidate(dentry, flags);
 }