Merge branch 'vfs-scale-working' of git://git.kernel.org/pub/scm/linux/kernel/git/npiggin/linux-npiggin

* 'vfs-scale-working' of git://git.kernel.org/pub/scm/linux/kernel/git/npiggin/linux-npiggin: (57 commits)
  fs: scale mntget/mntput
  fs: rename vfsmount counter helpers
  fs: implement faster dentry memcmp
  fs: prefetch inode data in dcache lookup
  fs: improve scalability of pseudo filesystems
  fs: dcache per-inode inode alias locking
  fs: dcache per-bucket dcache hash locking
  bit_spinlock: add required includes
  kernel: add bl_list
  xfs: provide simple rcu-walk ACL implementation
  btrfs: provide simple rcu-walk ACL implementation
  ext2,3,4: provide simple rcu-walk ACL implementation
  fs: provide simple rcu-walk generic_check_acl implementation
  fs: provide rcu-walk aware permission i_ops
  fs: rcu-walk aware d_revalidate method
  fs: cache optimise dentry and inode for rcu-walk
  fs: dcache reduce branches in lookup path
  fs: dcache remove d_mounted
  fs: fs_struct use seqlock
  fs: rcu-walk for path lookup
  ...

1 files changed, 26 insertions, 10 deletions

diff --git a/fs/fs_struct.c b/fs/fs_struct.c
index ed45a9cf5f3d..68ca487bedb1 100644
--- a/fs/fs_struct.c
+++ b/fs/fs_struct.c
@@ -14,12 +14,14 @@ void set_fs_root(struct fs_struct *fs, struct path *path)
 	struct path old_root;
 
 	spin_lock(&fs->lock);
+	write_seqcount_begin(&fs->seq);
 	old_root = fs->root;
 	fs->root = *path;
-	path_get(path);
+	path_get_long(path);
+	write_seqcount_end(&fs->seq);
 	spin_unlock(&fs->lock);
 	if (old_root.dentry)
-		path_put(&old_root);
+		path_put_long(&old_root);
 }
 
 /*
@@ -31,13 +33,15 @@ void set_fs_pwd(struct fs_struct *fs, struct path *path)
 	struct path old_pwd;
 
 	spin_lock(&fs->lock);
+	write_seqcount_begin(&fs->seq);
 	old_pwd = fs->pwd;
 	fs->pwd = *path;
-	path_get(path);
+	path_get_long(path);
+	write_seqcount_end(&fs->seq);
 	spin_unlock(&fs->lock);
 
 	if (old_pwd.dentry)
-		path_put(&old_pwd);
+		path_put_long(&old_pwd);
 }
 
 void chroot_fs_refs(struct path *old_root, struct path *new_root)
@@ -52,31 +56,33 @@ void chroot_fs_refs(struct path *old_root, struct path *new_root)
 		fs = p->fs;
 		if (fs) {
 			spin_lock(&fs->lock);
+			write_seqcount_begin(&fs->seq);
 			if (fs->root.dentry == old_root->dentry
 			    && fs->root.mnt == old_root->mnt) {
-				path_get(new_root);
+				path_get_long(new_root);
 				fs->root = *new_root;
 				count++;
 			}
 			if (fs->pwd.dentry == old_root->dentry
 			    && fs->pwd.mnt == old_root->mnt) {
-				path_get(new_root);
+				path_get_long(new_root);
 				fs->pwd = *new_root;
 				count++;
 			}
+			write_seqcount_end(&fs->seq);
 			spin_unlock(&fs->lock);
 		}
 		task_unlock(p);
 	} while_each_thread(g, p);
 	read_unlock(&tasklist_lock);
 	while (count--)
-		path_put(old_root);
+		path_put_long(old_root);
 }
 
 void free_fs_struct(struct fs_struct *fs)
 {
-	path_put(&fs->root);
-	path_put(&fs->pwd);
+	path_put_long(&fs->root);
+	path_put_long(&fs->pwd);
 	kmem_cache_free(fs_cachep, fs);
 }
 
@@ -88,8 +94,10 @@ void exit_fs(struct task_struct *tsk)
 		int kill;
 		task_lock(tsk);
 		spin_lock(&fs->lock);
+		write_seqcount_begin(&fs->seq);
 		tsk->fs = NULL;
 		kill = !--fs->users;
+		write_seqcount_end(&fs->seq);
 		spin_unlock(&fs->lock);
 		task_unlock(tsk);
 		if (kill)
@@ -105,8 +113,15 @@ struct fs_struct *copy_fs_struct(struct fs_struct *old)
 		fs->users = 1;
 		fs->in_exec = 0;
 		spin_lock_init(&fs->lock);
+		seqcount_init(&fs->seq);
 		fs->umask = old->umask;
-		get_fs_root_and_pwd(old, &fs->root, &fs->pwd);
+
+		spin_lock(&old->lock);
+		fs->root = old->root;
+		path_get_long(&fs->root);
+		fs->pwd = old->pwd;
+		path_get_long(&fs->pwd);
+		spin_unlock(&old->lock);
 	}
 	return fs;
 }
@@ -144,6 +159,7 @@ EXPORT_SYMBOL(current_umask);
 struct fs_struct init_fs = {
 	.users		= 1,
 	.lock		= __SPIN_LOCK_UNLOCKED(init_fs.lock),
+	.seq		= SEQCNT_ZERO,
 	.umask		= 0022,
 };