tidy up namei.c a bit
Al Viro [Wed, 18 Jul 2012 16:43:19 +0000 (20:43 +0400)]
locking/unlocking for rcu walk taken to a couple of inline helpers

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

fs/namei.c

index d4d15bb..2ccc35c 100644 (file)
@@ -427,6 +427,18 @@ EXPORT_SYMBOL(path_put);
  * to restart the path walk from the beginning in ref-walk mode.
  */
 
+static inline void lock_rcu_walk(void)
+{
+       br_read_lock(&vfsmount_lock);
+       rcu_read_lock();
+}
+
+static inline void unlock_rcu_walk(void)
+{
+       rcu_read_unlock();
+       br_read_unlock(&vfsmount_lock);
+}
+
 /**
  * unlazy_walk - try to switch to ref-walk mode.
  * @nd: nameidata pathwalk data
@@ -480,8 +492,7 @@ static int unlazy_walk(struct nameidata *nd, struct dentry *dentry)
        }
        mntget(nd->path.mnt);
 
-       rcu_read_unlock();
-       br_read_unlock(&vfsmount_lock);
+       unlock_rcu_walk();
        nd->flags &= ~LOOKUP_RCU;
        return 0;
 
@@ -522,15 +533,13 @@ static int complete_walk(struct nameidata *nd)
                spin_lock(&dentry->d_lock);
                if (unlikely(!__d_rcu_to_refcount(dentry, nd->seq))) {
                        spin_unlock(&dentry->d_lock);
-                       rcu_read_unlock();
-                       br_read_unlock(&vfsmount_lock);
+                       unlock_rcu_walk();
                        return -ECHILD;
                }
                BUG_ON(nd->inode != dentry->d_inode);
                spin_unlock(&dentry->d_lock);
                mntget(nd->path.mnt);
-               rcu_read_unlock();
-               br_read_unlock(&vfsmount_lock);
+               unlock_rcu_walk();
        }
 
        if (likely(!(nd->flags & LOOKUP_JUMPED)))
@@ -985,8 +994,7 @@ failed:
        nd->flags &= ~LOOKUP_RCU;
        if (!(nd->flags & LOOKUP_ROOT))
                nd->root.mnt = NULL;
-       rcu_read_unlock();
-       br_read_unlock(&vfsmount_lock);
+       unlock_rcu_walk();
        return -ECHILD;
 }
 
@@ -1323,8 +1331,7 @@ static void terminate_walk(struct nameidata *nd)
                nd->flags &= ~LOOKUP_RCU;
                if (!(nd->flags & LOOKUP_ROOT))
                        nd->root.mnt = NULL;
-               rcu_read_unlock();
-               br_read_unlock(&vfsmount_lock);
+               unlock_rcu_walk();
        }
 }
 
@@ -1691,8 +1698,7 @@ static int path_init(int dfd, const char *name, unsigned int flags,
                nd->path = nd->root;
                nd->inode = inode;
                if (flags & LOOKUP_RCU) {
-                       br_read_lock(&vfsmount_lock);
-                       rcu_read_lock();
+                       lock_rcu_walk();
                        nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
                } else {
                        path_get(&nd->path);
@@ -1704,8 +1710,7 @@ static int path_init(int dfd, const char *name, unsigned int flags,
 
        if (*name=='/') {
                if (flags & LOOKUP_RCU) {
-                       br_read_lock(&vfsmount_lock);
-                       rcu_read_lock();
+                       lock_rcu_walk();
                        set_root_rcu(nd);
                } else {
                        set_root(nd);
@@ -1717,8 +1722,7 @@ static int path_init(int dfd, const char *name, unsigned int flags,
                        struct fs_struct *fs = current->fs;
                        unsigned seq;
 
-                       br_read_lock(&vfsmount_lock);
-                       rcu_read_lock();
+                       lock_rcu_walk();
 
                        do {
                                seq = read_seqcount_begin(&fs->seq);
@@ -1753,8 +1757,7 @@ static int path_init(int dfd, const char *name, unsigned int flags,
                        if (fput_needed)
                                *fp = file;
                        nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
-                       br_read_lock(&vfsmount_lock);
-                       rcu_read_lock();
+                       lock_rcu_walk();
                } else {
                        path_get(&file->f_path);
                        fput_light(file, fput_needed);