fuse: readdirplus: fix dentry leak

In case d_lookup() returns a dentry with d_inode == NULL, the dentry is not
returned with dput(). This results in triggering a BUG() in
shrink_dcache_for_umount_subtree():

  BUG: Dentry ...{i=0,n=...} still in use (1) [unmount of fuse fuse]

[SzM: need to d_drop() as well]

Reported-by: Justin Clift <jclift@redhat.com>
Signed-off-by: Niels de Vos <ndevos@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Tested-by: Brian Foster <bfoster@redhat.com>
Tested-by: Niels de Vos <ndevos@redhat.com>
CC: stable@vger.kernel.org

1 files changed, 8 insertions, 5 deletions

diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 0eda52738ec4..2ae5308174e2 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -1227,9 +1227,15 @@ static int fuse_direntplus_link(struct file *file,
 
         name.hash = full_name_hash(name.name, name.len);
         dentry = d_lookup(parent, &name);
-        if (dentry && dentry->d_inode) {
+        if (dentry) {
                 inode = dentry->d_inode;
-                if (get_node_id(inode) == o->nodeid) {
+                if (!inode) {
+                        d_drop(dentry);
+                } else if (get_node_id(inode) != o->nodeid) {
+                        err = d_invalidate(dentry);
+                        if (err)
+                                goto out;
+                } else {
                         struct fuse_inode *fi;
                         fi = get_fuse_inode(inode);
                         spin_lock(&fc->lock);
@@ -1242,9 +1248,6 @@ static int fuse_direntplus_link(struct file *file,
                          */
                         goto found;
                 }
-                err = d_invalidate(dentry);
-                if (err)
-                        goto out;
                 dput(dentry);
                 dentry = NULL;
         }