fold release_mounts() into namespace_unlock()
Al Viro [Sat, 16 Mar 2013 19:12:40 +0000 (15:12 -0400)]
... and provide namespace_lock() as a trivial wrapper;
switch to those two consistently.

Result is patterned after rtnl_lock/rtnl_unlock pair.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/namespace.c

index fa93d54..ed0708f 100644 (file)
@@ -1121,11 +1121,21 @@ EXPORT_SYMBOL(may_umount);
 
 static LIST_HEAD(unmounted);   /* protected by namespace_sem */
 
-static void release_mounts(struct list_head *head)
+static void namespace_unlock(void)
 {
        struct mount *mnt;
-       while (!list_empty(head)) {
-               mnt = list_first_entry(head, struct mount, mnt_hash);
+       LIST_HEAD(head);
+
+       if (likely(list_empty(&unmounted))) {
+               up_write(&namespace_sem);
+               return;
+       }
+
+       list_splice_init(&unmounted, &head);
+       up_write(&namespace_sem);
+
+       while (!list_empty(&head)) {
+               mnt = list_first_entry(&head, struct mount, mnt_hash);
                list_del_init(&mnt->mnt_hash);
                if (mnt_has_parent(mnt)) {
                        struct dentry *dentry;
@@ -1145,12 +1155,9 @@ static void release_mounts(struct list_head *head)
        }
 }
 
-static void namespace_unlock(void)
+static inline void namespace_lock(void)
 {
-       LIST_HEAD(head);
-       list_splice_init(&unmounted, &head);
-       up_write(&namespace_sem);
-       release_mounts(&head);
+       down_write(&namespace_sem);
 }
 
 /*
@@ -1256,7 +1263,7 @@ static int do_umount(struct mount *mnt, int flags)
                return retval;
        }
 
-       down_write(&namespace_sem);
+       namespace_lock();
        br_write_lock(&vfsmount_lock);
        event++;
 
@@ -1412,7 +1419,7 @@ out:
 struct vfsmount *collect_mounts(struct path *path)
 {
        struct mount *tree;
-       down_write(&namespace_sem);
+       namespace_lock();
        tree = copy_tree(real_mount(path->mnt), path->dentry,
                         CL_COPY_ALL | CL_PRIVATE);
        namespace_unlock();
@@ -1423,7 +1430,7 @@ struct vfsmount *collect_mounts(struct path *path)
 
 void drop_collected_mounts(struct vfsmount *mnt)
 {
-       down_write(&namespace_sem);
+       namespace_lock();
        br_write_lock(&vfsmount_lock);
        umount_tree(real_mount(mnt), 0);
        br_write_unlock(&vfsmount_lock);
@@ -1593,18 +1600,18 @@ retry:
                mutex_unlock(&dentry->d_inode->i_mutex);
                return ERR_PTR(-ENOENT);
        }
-       down_write(&namespace_sem);
+       namespace_lock();
        mnt = lookup_mnt(path);
        if (likely(!mnt)) {
                struct mountpoint *mp = new_mountpoint(dentry);
                if (IS_ERR(mp)) {
-                       up_write(&namespace_sem);
+                       namespace_unlock();
                        mutex_unlock(&dentry->d_inode->i_mutex);
                        return mp;
                }
                return mp;
        }
-       up_write(&namespace_sem);
+       namespace_unlock();
        mutex_unlock(&path->dentry->d_inode->i_mutex);
        path_put(path);
        path->mnt = mnt;
@@ -1667,7 +1674,7 @@ static int do_change_type(struct path *path, int flag)
        if (!type)
                return -EINVAL;
 
-       down_write(&namespace_sem);
+       namespace_lock();
        if (type == MS_SHARED) {
                err = invent_group_ids(mnt, recurse);
                if (err)
@@ -1680,7 +1687,7 @@ static int do_change_type(struct path *path, int flag)
        br_write_unlock(&vfsmount_lock);
 
  out_unlock:
-       up_write(&namespace_sem);
+       namespace_unlock();
        return err;
 }
 
@@ -2016,11 +2023,11 @@ int finish_automount(struct vfsmount *m, struct path *path)
 fail:
        /* remove m from any expiration list it may be on */
        if (!list_empty(&mnt->mnt_expire)) {
-               down_write(&namespace_sem);
+               namespace_lock();
                br_write_lock(&vfsmount_lock);
                list_del_init(&mnt->mnt_expire);
                br_write_unlock(&vfsmount_lock);
-               up_write(&namespace_sem);
+               namespace_unlock();
        }
        mntput(m);
        mntput(m);
@@ -2034,13 +2041,13 @@ fail:
  */
 void mnt_set_expiry(struct vfsmount *mnt, struct list_head *expiry_list)
 {
-       down_write(&namespace_sem);
+       namespace_lock();
        br_write_lock(&vfsmount_lock);
 
        list_add_tail(&real_mount(mnt)->mnt_expire, expiry_list);
 
        br_write_unlock(&vfsmount_lock);
-       up_write(&namespace_sem);
+       namespace_unlock();
 }
 EXPORT_SYMBOL(mnt_set_expiry);
 
@@ -2057,7 +2064,7 @@ void mark_mounts_for_expiry(struct list_head *mounts)
        if (list_empty(mounts))
                return;
 
-       down_write(&namespace_sem);
+       namespace_lock();
        br_write_lock(&vfsmount_lock);
 
        /* extract from the expiration list every vfsmount that matches the
@@ -2373,7 +2380,7 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns,
        if (IS_ERR(new_ns))
                return new_ns;
 
-       down_write(&namespace_sem);
+       namespace_lock();
        /* First pass: copy the tree topology */
        copy_flags = CL_COPY_ALL | CL_EXPIRE;
        if (user_ns != mnt_ns->user_ns)
@@ -2733,7 +2740,7 @@ void put_mnt_ns(struct mnt_namespace *ns)
 {
        if (!atomic_dec_and_test(&ns->count))
                return;
-       down_write(&namespace_sem);
+       namespace_lock();
        br_write_lock(&vfsmount_lock);
        umount_tree(ns->root, 0);
        br_write_unlock(&vfsmount_lock);