fold release_mounts() into namespace_unlock()

... 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>

1 files changed, 30 insertions, 23 deletions

diff --git a/fs/namespace.c b/fs/namespace.c
index fa93d54d21e8..ed0708f2415f 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -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);