On Sun, 2010-10-10 at 05:36 -0400, Christoph Hellwig wrote:
> plain text document attachment (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@xxxxxx>
Nope this is fine, we were doing lots of extra work for little benefit
before.
Acked-by: Eric Paris <eparis@xxxxxxxxxx>
> Index: linux-2.6/fs/notify/fsnotify.c
> ===================================================================
> --- linux-2.6.orig/fs/notify/fsnotify.c 2010-10-10 09:35:58.488004195 +0200
> +++ linux-2.6/fs/notify/fsnotify.c 2010-10-10 09:53:53.103010272 +0200
> @@ -88,8 +88,6 @@ void __fsnotify_parent(struct path *path
> {
> 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
> 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
> 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);
>
>
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