vfs: add d_canonical_path for stacked filesystem support

[firefly-linux-kernel-4.4.55.git] / fs / notify / inotify / inotify_user.c

diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c
index b8d08d0d0a4dbe061b9336dd7f861d32e13c8618..9a0cd02cf3dc65e64cf60ab950b679a940c2550e 100644 (file)
--- a/fs/notify/inotify/inotify_user.c
+++ b/fs/notify/inotify/inotify_user.c
@@ -702,6 +702,8 @@ SYSCALL_DEFINE3(inotify_add_watch, int, fd, const char __user *, pathname,
        struct fsnotify_group *group;
        struct inode *inode;
        struct path path;
+       struct path alteredpath;
+       struct path *canonical_path = &path;
        struct fd f;
        int ret;
        unsigned flags = 0;
@@ -741,13 +743,22 @@ SYSCALL_DEFINE3(inotify_add_watch, int, fd, const char __user *, pathname,
        if (ret)
                goto fput_and_out;
 
+       /* support stacked filesystems */
+       if(path.dentry && path.dentry->d_op) {
+               if (path.dentry->d_op->d_canonical_path) {
+                       path.dentry->d_op->d_canonical_path(path.dentry, &alteredpath);
+                       canonical_path = &alteredpath;
+                       path_put(&path);
+               }
+       }
+
        /* inode held in place by reference to path; group by fget on fd */
-       inode = path.dentry->d_inode;
+       inode = canonical_path->dentry->d_inode;
        group = f.file->private_data;
 
        /* create/update an inode mark */
        ret = inotify_update_watch(group, inode, mask);
-       path_put(&path);
+       path_put(canonical_path);
 fput_and_out:
        fdput(f);
        return ret;
@@ -814,7 +825,7 @@ static int __init inotify_user_setup(void)
        BUILD_BUG_ON(IN_ISDIR != FS_ISDIR);
        BUILD_BUG_ON(IN_ONESHOT != FS_IN_ONESHOT);
 
-       BUG_ON(hweight32(ALL_INOTIFY_BITS) != 21);
+       BUG_ON(hweight32(ALL_INOTIFY_BITS) != 22);
 
        inotify_inode_mark_cachep = KMEM_CACHE(inotify_inode_mark, SLAB_PANIC);