nfs: dont unhash target if renaming a directory

Move unhashing the target to after the check for existence and being a
non-directory.

If renaming a directory then the VFS already unhashes the target if it
is not busy.  If it's busy then acquiring more references during the
rename makes no difference.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 29 insertions, 27 deletions

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 11d0c4cffffc..76b7f539d76e 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1579,15 +1579,6 @@ static int nfs_rename(struct inode *old_dir, struct dentry *old_dentry,
         struct dentry *dentry = NULL, *rehash = NULL;
         int error = -EBUSY;
 
-        /*
-         * To prevent any new references to the target during the rename,
-         * we unhash the dentry in advance.
-         */
-        if (!d_unhashed(new_dentry)) {
-                d_drop(new_dentry);
-                rehash = new_dentry;
-        }
-
         dfprintk(VFS, "NFS: rename(%s/%s -> %s/%s, ct=%d)\n",
                  old_dentry->d_parent->d_name.name, old_dentry->d_name.name,
                  new_dentry->d_parent->d_name.name, new_dentry->d_name.name,
@@ -1599,25 +1590,36 @@ static int nfs_rename(struct inode *old_dir, struct dentry *old_dentry,
          * silly-rename succeeds, the copied dentry is hashed and becomes
          * the new target.
          */
-        if (new_inode && !S_ISDIR(new_inode->i_mode) &&
-            atomic_read(&new_dentry->d_count) > 2) {
-                int err;
-                /* copy the target dentry's name */
-                dentry = d_alloc(new_dentry->d_parent,
-                                 &new_dentry->d_name);
-                if (!dentry)
-                        goto out;
+        if (new_inode && !S_ISDIR(new_inode->i_mode)) {
+                /*
+                 * To prevent any new references to the target during the
+                 * rename, we unhash the dentry in advance.
+                 */
+                if (!d_unhashed(new_dentry)) {
+                        d_drop(new_dentry);
+                        rehash = new_dentry;
+                }
 
-                /* silly-rename the existing target ... */
-                err = nfs_sillyrename(new_dir, new_dentry);
-                if (!err) {
-                        new_dentry = rehash = dentry;
-                        new_inode = NULL;
-                        /* instantiate the replacement target */
-                        d_instantiate(new_dentry, NULL);
-                } else if (atomic_read(&new_dentry->d_count) > 1)
-                        /* dentry still busy? */
-                        goto out;
+                if (atomic_read(&new_dentry->d_count) > 2) {
+                        int err;
+
+                        /* copy the target dentry's name */
+                        dentry = d_alloc(new_dentry->d_parent,
+                                         &new_dentry->d_name);
+                        if (!dentry)
+                                goto out;
+
+                        /* silly-rename the existing target ... */
+                        err = nfs_sillyrename(new_dir, new_dentry);
+                        if (!err) {
+                                new_dentry = rehash = dentry;
+                                new_inode = NULL;
+                                /* instantiate the replacement target */
+                                d_instantiate(new_dentry, NULL);
+                        } else if (atomic_read(&new_dentry->d_count) > 1)
+                                /* dentry still busy? */
+                                goto out;
+                }
         }
 
         /*