[PATCH] fuse: locking fix for nlookup

An inode could be returned by independent parallel lookups, in this case an
update of the lookup counter could be lost resulting in a memory leak in
userspace.

Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 4 insertions, 0 deletions

diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index a8f65c11aa2c..7ecfe95795cd 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -163,7 +163,9 @@ static int fuse_dentry_revalidate(struct dentry *entry, struct nameidata *nd)
                                 fuse_send_forget(fc, req, outarg.nodeid, 1);
                                 return 0;
                         }
+                        spin_lock(&fc->lock);
                         fi->nlookup ++;
+                        spin_unlock(&fc->lock);
                 }
                 fuse_put_request(fc, req);
                 if (err || (outarg.attr.mode ^ inode->i_mode) & S_IFMT)
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 8e106163aaed..e9114237f31f 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -195,7 +195,9 @@ struct inode *fuse_iget(struct super_block *sb, unsigned long nodeid,
         }
 
         fi = get_fuse_inode(inode);
+        spin_lock(&fc->lock);
         fi->nlookup ++;
+        spin_unlock(&fc->lock);
         fuse_change_attributes(inode, attr);
         return inode;
 }