fs/9p: Add fid before dentry instantiation

BugLink: http://bugs.launchpad.net/bugs/868628

commit 5441ae5eb3614d3c28f77073370738a2820c88e4 upstream.

d_instantiate marks the dentry positive. So a parallel lookup and mkdir of
the directory can find dentry that doesn't have fid attached. This can result
in both the code path doing v9fs_fid_add which results in v9fs_dentry leak.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 5 insertions, 7 deletions

diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index 35d412187d0..ad7aae4b03d 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -633,13 +633,11 @@ v9fs_create(struct v9fs_session_info *v9ses, struct inode *dir,
                 P9_DPRINTK(P9_DEBUG_VFS, "inode creation failed %d\n", err);
                 goto error;
         }
-        d_instantiate(dentry, inode);
         err = v9fs_fid_add(dentry, fid);
         if (err < 0)
                 goto error;
-
+        d_instantiate(dentry, inode);
         return ofid;
-
 error:
         if (ofid)
                 p9_client_clunk(ofid);
diff --git a/fs/9p/vfs_inode_dotl.c b/fs/9p/vfs_inode_dotl.c
index 185ce37ee3f..0a1723587fa 100644
--- a/fs/9p/vfs_inode_dotl.c
+++ b/fs/9p/vfs_inode_dotl.c
@@ -281,10 +281,10 @@ v9fs_vfs_create_dotl(struct inode *dir, struct dentry *dentry, int omode,
                 P9_DPRINTK(P9_DEBUG_VFS, "inode creation failed %d\n", err);
                 goto error;
         }
-        d_instantiate(dentry, inode);
         err = v9fs_fid_add(dentry, fid);
         if (err < 0)
                 goto error;
+        d_instantiate(dentry, inode);
 
         /* Now set the ACL based on the default value */
         v9fs_set_create_acl(dentry, &dacl, &pacl);
@@ -403,10 +403,10 @@ static int v9fs_vfs_mkdir_dotl(struct inode *dir,
                                 err);
                         goto error;
                 }
-                d_instantiate(dentry, inode);
                 err = v9fs_fid_add(dentry, fid);
                 if (err < 0)
                         goto error;
+                d_instantiate(dentry, inode);
                 fid = NULL;
         } else {
                 /*
@@ -657,10 +657,10 @@ v9fs_vfs_symlink_dotl(struct inode *dir, struct dentry *dentry,
                                         err);
                         goto error;
                 }
-                d_instantiate(dentry, inode);
                 err = v9fs_fid_add(dentry, fid);
                 if (err < 0)
                         goto error;
+                d_instantiate(dentry, inode);
                 fid = NULL;
         } else {
                 /* Not in cached mode. No need to populate inode with stat */
@@ -810,10 +810,10 @@ v9fs_vfs_mknod_dotl(struct inode *dir, struct dentry *dentry, int omode,
                                 err);
                         goto error;
                 }
-                d_instantiate(dentry, inode);
                 err = v9fs_fid_add(dentry, fid);
                 if (err < 0)
                         goto error;
+                d_instantiate(dentry, inode);
                 fid = NULL;
         } else {
                 /*