1 files changed, 28 insertions, 6 deletions

diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
index 9dc7e7a64e10..d0859f72d2d6 100644
--- a/fs/kernfs/mount.c
+++ b/fs/kernfs/mount.c
@@ -20,6 +20,7 @@
 #include "kernfs-internal.h"
 
 struct kmem_cache *kernfs_node_cache, *kernfs_iattrs_cache;
+struct kernfs_global_locks *kernfs_locks;
 
 static int kernfs_sop_show_options(struct seq_file *sf, struct dentry *dentry)
 {
@@ -236,6 +237,7 @@ struct dentry *kernfs_node_dentry(struct kernfs_node *kn,
 static int kernfs_fill_super(struct super_block *sb, struct kernfs_fs_context *kfc)
 {
 	struct kernfs_super_info *info = kernfs_info(sb);
+	struct kernfs_root *kf_root = kfc->root;
 	struct inode *inode;
 	struct dentry *root;
 
@@ -255,9 +257,9 @@ static int kernfs_fill_super(struct super_block *sb, struct kernfs_fs_context *k
 	sb->s_shrink.seeks = 0;
 
 	/* get root inode, initialize and unlock it */
-	mutex_lock(&kernfs_mutex);
+	down_read(&kf_root->kernfs_rwsem);
 	inode = kernfs_get_inode(sb, info->root->kn);
-	mutex_unlock(&kernfs_mutex);
+	up_read(&kf_root->kernfs_rwsem);
 	if (!inode) {
 		pr_debug("kernfs: could not get root inode\n");
 		return -ENOMEM;
@@ -334,6 +336,7 @@ int kernfs_get_tree(struct fs_context *fc)
 
 	if (!sb->s_root) {
 		struct kernfs_super_info *info = kernfs_info(sb);
+		struct kernfs_root *root = kfc->root;
 
 		kfc->new_sb_created = true;
 
@@ -344,9 +347,9 @@ int kernfs_get_tree(struct fs_context *fc)
 		}
 		sb->s_flags |= SB_ACTIVE;
 
-		mutex_lock(&kernfs_mutex);
+		down_write(&root->kernfs_rwsem);
 		list_add(&info->node, &info->root->supers);
-		mutex_unlock(&kernfs_mutex);
+		up_write(&root->kernfs_rwsem);
 	}
 
 	fc->root = dget(sb->s_root);
@@ -371,10 +374,11 @@ void kernfs_free_fs_context(struct fs_context *fc)
 void kernfs_kill_sb(struct super_block *sb)
 {
 	struct kernfs_super_info *info = kernfs_info(sb);
+	struct kernfs_root *root = info->root;
 
-	mutex_lock(&kernfs_mutex);
+	down_write(&root->kernfs_rwsem);
 	list_del(&info->node);
-	mutex_unlock(&kernfs_mutex);
+	up_write(&root->kernfs_rwsem);
 
 	/*
 	 * Remove the superblock from fs_supers/s_instances
@@ -384,6 +388,22 @@ void kernfs_kill_sb(struct super_block *sb)
 	kfree(info);
 }
 
+static void __init kernfs_mutex_init(void)
+{
+	int count;
+
+	for (count = 0; count < NR_KERNFS_LOCKS; count++)
+		mutex_init(&kernfs_locks->open_file_mutex[count]);
+}
+
+static void __init kernfs_lock_init(void)
+{
+	kernfs_locks = kmalloc(sizeof(struct kernfs_global_locks), GFP_KERNEL);
+	WARN_ON(!kernfs_locks);
+
+	kernfs_mutex_init();
+}
+
 void __init kernfs_init(void)
 {
 	kernfs_node_cache = kmem_cache_create("kernfs_node_cache",
@@ -394,4 +414,6 @@ void __init kernfs_init(void)
 	kernfs_iattrs_cache  = kmem_cache_create("kernfs_iattrs_cache",
 					      sizeof(struct kernfs_iattrs),
 					      0, SLAB_PANIC, NULL);
+
+	kernfs_lock_init();
 }