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,
 };