fsnotify: use dget_parent

Use dget_parent instead of opencoding it.  This simplifies the code, but
more importanly prepares for the more complicated locking for a parent
dget in the dcache scale patch series.

It means we do grab a reference to the parent now if need to be watched,
but not with the specified mask.  If this turns out to be a problem
we'll have to revisit it, but for now let's keep as much as possible
dcache internals inside dcache.[ch].

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 5 insertions, 28 deletions

diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
index 36802420d69a..4498a208df94 100644
--- a/fs/notify/fsnotify.c
+++ b/fs/notify/fsnotify.c
@@ -88,8 +88,6 @@ void __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask)
 {
         struct dentry *parent;
         struct inode *p_inode;
-        bool send = false;
-        bool should_update_children = false;
 
         if (!dentry)
                 dentry = path->dentry;
@@ -97,29 +95,12 @@ void __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask)
         if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED))
                 return;
 
-        spin_lock(&dentry->d_lock);
-        parent = dentry->d_parent;
+        parent = dget_parent(dentry);
         p_inode = parent->d_inode;
 
-        if (fsnotify_inode_watches_children(p_inode)) {
-                if (p_inode->i_fsnotify_mask & mask) {
-                        dget(parent);
-                        send = true;
-                }
-        } else {
-                /*
-                 * The parent doesn't care about events on it's children but
-                 * at least one child thought it did.  We need to run all the
-                 * children and update their d_flags to let them know p_inode
-                 * doesn't care about them any more.
-                 */
-                dget(parent);
-                should_update_children = true;
-        }
-
-        spin_unlock(&dentry->d_lock);
-
-        if (send) {
+        if (unlikely(!fsnotify_inode_watches_children(p_inode)))
+                __fsnotify_update_child_dentry_flags(p_inode);
+        else if (p_inode->i_fsnotify_mask & mask) {
                 /* we are notifying a parent so come up with the new mask which
                  * specifies these are events which came from a child. */
                 mask |= FS_EVENT_ON_CHILD;
@@ -130,13 +111,9 @@ void __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask)
                 else
                         fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE,
                                  dentry->d_name.name, 0);
-                dput(parent);
         }
 
-        if (unlikely(should_update_children)) {
-                __fsnotify_update_child_dentry_flags(p_inode);
-                dput(parent);
-        }
+        dput(parent);
 }
 EXPORT_SYMBOL_GPL(__fsnotify_parent);