fs: dcache scale dentry refcount

Make d_count non-atomic and protect it with d_lock. This allows us to ensure a
0 refcount dentry remains 0 without dcache_lock. It is also fairly natural when
we start protecting many other dentry members with d_lock.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>

2 files changed, 2 insertions, 3 deletions

diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c
index 20024a9..e9acea4 100644
--- a/fs/configfs/dir.c
+++ b/fs/configfs/dir.c
@@ -394,8 +394,7 @@ static void remove_dir(struct dentry * d)
 	if (d->d_inode)
 		simple_rmdir(parent->d_inode,d);
 
-	pr_debug(" o %s removing done (%d)\n",d->d_name.name,
-		 atomic_read(&d->d_count));
+	pr_debug(" o %s removing done (%d)\n",d->d_name.name, d->d_count);
 
 	dput(parent);
 }
diff --git a/fs/configfs/inode.c b/fs/configfs/inode.c
index 253476d..79b3776 100644
--- a/fs/configfs/inode.c
+++ b/fs/configfs/inode.c
@@ -253,7 +253,7 @@ void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
 		spin_lock(&dcache_lock);
 		spin_lock(&dentry->d_lock);
 		if (!(d_unhashed(dentry) && dentry->d_inode)) {
-			dget_locked(dentry);
+			dget_locked_dlock(dentry);
 			__d_drop(dentry);
 			spin_unlock(&dentry->d_lock);
 			spin_unlock(&dcache_lock);