NFS: Fix a race in sillyrename

lookup() and sillyrename() can race one another because the sillyrename()
completion cannot take the parent directory's inode->i_mutex since the
latter may be held by whoever is calling dput().

We therefore have little option but to add extra locking to ensure that
nfs_lookup() and nfs_atomic_open() do not race with the sillyrename
completion.
If somebody has looked up the sillyrenamed file in the meantime, we just
transfer the sillydelete information to the new dentry.

Please refer to the bug-report at
	http://bugzilla.linux-nfs.org/show_bug.cgi?id=150

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

1 files changed, 8 insertions, 0 deletions

diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index c5164c257f71..e82a6ebc725d 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -160,6 +160,12 @@ struct nfs_inode {
         /* Open contexts for shared mmap writes */
         struct list_head        open_files;
 
+        /* Number of in-flight sillydelete RPC calls */
+        atomic_t                silly_count;
+        /* List of deferred sillydelete requests */
+        struct hlist_head       silly_list;
+        wait_queue_head_t       waitqueue;
+
 #ifdef CONFIG_NFS_V4
         struct nfs4_cached_acl  *nfs4_acl;
         /* NFSv4 state */
@@ -394,6 +400,8 @@ extern void nfs_release_automount_timer(void);
  */
 extern int  nfs_async_unlink(struct inode *dir, struct dentry *dentry);
 extern void nfs_complete_unlink(struct dentry *dentry, struct inode *);
+extern void nfs_block_sillyrename(struct dentry *dentry);
+extern void nfs_unblock_sillyrename(struct dentry *dentry);
 
 /*
  * linux/fs/nfs/write.c