Merge tag 'pull-dcache' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull dcache updates from Al Viro:

 - d_alloc_parallel() API change (Neil's with my changes)

 - NORCU fixes

 - Reorganization and simplification of dentry eviction logic

 - Simplifying rcu_read_lock() scopes in fs/dcache.c

 - Secondary roots work - getting rid of NFS fake root dentries and
   dealing with remaining shrink_dcache_for_umount() and
   shrink_dentry_list() races

 - making cursors NORCU (surprisingly easy)

* tag 'pull-dcache' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (22 commits)
  make cursors NORCU
  nfs: get rid of fake root dentries
  wind ->s_roots via ->d_sib instead of ->d_hash
  shrink_dentry_tree(): unify the calls of shrink_dentry_list()
  shrinking rcu_read_lock() scope in d_alloc_parallel()
  d_walk(): shrink rcu_read_lock() scope
  document dentry_kill()
  adjust calling conventions of lock_for_kill(), fold __dentry_kill() into dentry_kill()
  Document rcu_read_lock() use in select_collect2()
  Shift rcu_read_{,un}lock() inside fast_dput()
  simplify safety for lock_for_kill() slowpath
  fold lock_for_kill() and __dentry_kill() into common helper
  fold lock_for_kill() into shrink_kill()
  shrink_dentry_list(): start with removing from shrink list
  d_prune_aliases(): make sure to skip NORCU aliases
  kill d_dispose_if_unused()
  make to_shrink_list() return whether it has moved dentry to list
  select_collect(): ignore dentries on shrink lists if they have positive refcounts
  find_acceptable_alias(): skip NORCU aliases with zero refcount
  fix a race between d_find_any_alias() and final dput() of NORCU dentries
  ...

3 files changed, 5 insertions, 39 deletions

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 1b9c368fb133..2f5f26f93238 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -726,7 +726,6 @@ void nfs_prime_dcache(struct dentry *parent, struct nfs_entry *entry,
 		unsigned long dir_verifier)
 {
 	struct qstr filename = QSTR_INIT(entry->name, entry->len);
-	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
 	struct dentry *dentry;
 	struct dentry *alias;
 	struct inode *inode;
@@ -755,7 +754,7 @@ void nfs_prime_dcache(struct dentry *parent, struct nfs_entry *entry,
 	dentry = d_lookup(parent, &filename);
 again:
 	if (!dentry) {
-		dentry = d_alloc_parallel(parent, &filename, &wq);
+		dentry = d_alloc_parallel(parent, &filename);
 		if (IS_ERR(dentry))
 			return;
 	}
@@ -2106,7 +2105,6 @@ int nfs_atomic_open(struct inode *dir, struct dentry *dentry,
 		    struct file *file, unsigned open_flags,
 		    umode_t mode)
 {
-	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
 	struct nfs_open_context *ctx;
 	struct dentry *res;
 	struct iattr attr = { .ia_valid = ATTR_OPEN };
@@ -2162,7 +2160,7 @@ int nfs_atomic_open(struct inode *dir, struct dentry *dentry,
 		d_drop(dentry);
 		switched = true;
 		dentry = d_alloc_parallel(dentry->d_parent,
-					  &dentry->d_name, &wq);
+					  &dentry->d_name);
 		if (IS_ERR(dentry))
 			return PTR_ERR(dentry);
 		if (unlikely(!d_in_lookup(dentry)))
diff --git a/fs/nfs/getroot.c b/fs/nfs/getroot.c
index eef0736beb67..ff7424bc4bec 100644
--- a/fs/nfs/getroot.c
+++ b/fs/nfs/getroot.c
@@ -33,35 +33,6 @@
 #define NFSDBG_FACILITY		NFSDBG_CLIENT
 
 /*
- * Set the superblock root dentry.
- * Note that this function frees the inode in case of error.
- */
-static int nfs_superblock_set_dummy_root(struct super_block *sb, struct inode *inode)
-{
-	/* The mntroot acts as the dummy root dentry for this superblock */
-	if (sb->s_root == NULL) {
-		sb->s_root = d_make_root(inode);
-		if (sb->s_root == NULL)
-			return -ENOMEM;
-		ihold(inode);
-		/*
-		 * Ensure that this dentry is invisible to d_find_alias().
-		 * Otherwise, it may be spliced into the tree by
-		 * d_splice_alias if a parent directory from the same
-		 * filesystem gets mounted at a later time.
-		 * This again causes shrink_dcache_for_umount_subtree() to
-		 * Oops, since the test for IS_ROOT() will fail.
-		 */
-		spin_lock(&d_inode(sb->s_root)->i_lock);
-		spin_lock(&sb->s_root->d_lock);
-		hlist_del_init(&sb->s_root->d_alias);
-		spin_unlock(&sb->s_root->d_lock);
-		spin_unlock(&d_inode(sb->s_root)->i_lock);
-	}
-	return 0;
-}
-
-/*
  * get a root dentry from the root filehandle
  */
 int nfs_get_root(struct super_block *s, struct fs_context *fc)
@@ -99,10 +70,6 @@ int nfs_get_root(struct super_block *s, struct fs_context *fc)
 		goto out_fattr;
 	}
 
-	error = nfs_superblock_set_dummy_root(s, inode);
-	if (error != 0)
-		goto out_fattr;
-
 	/* root dentries normally start off anonymous and get spliced in later
 	 * if the dentry tree reaches them; however if the dentry already
 	 * exists, we'll pick it up at this point and use it as the root
@@ -123,6 +90,8 @@ int nfs_get_root(struct super_block *s, struct fs_context *fc)
 		name = NULL;
 	}
 	spin_unlock(&root->d_lock);
+	if (!s->s_root)
+		s->s_root = dget(root);
 	fc->root = root;
 	if (server->caps & NFS_CAP_SECURITY_LABEL)
 		kflags |= SECURITY_LSM_NATIVE_LABELS;
diff --git a/fs/nfs/unlink.c b/fs/nfs/unlink.c
index df3ca4669df6..43ea897943c0 100644
--- a/fs/nfs/unlink.c
+++ b/fs/nfs/unlink.c
@@ -124,7 +124,7 @@ static int nfs_call_unlink(struct dentry *dentry, struct inode *inode, struct nf
 	struct dentry *alias;
 
 	down_read_non_owner(&NFS_I(dir)->rmdir_sem);
-	alias = d_alloc_parallel(dentry->d_parent, &data->args.name, &data->wq);
+	alias = d_alloc_parallel(dentry->d_parent, &data->args.name);
 	if (IS_ERR(alias)) {
 		up_read_non_owner(&NFS_I(dir)->rmdir_sem);
 		return 0;
@@ -185,7 +185,6 @@ nfs_async_unlink(struct dentry *dentry, const struct qstr *name)
 
 	data->cred = get_current_cred();
 	data->res.dir_attr = &data->dir_attr;
-	init_waitqueue_head(&data->wq);
 
 	status = -EBUSY;
 	spin_lock(&dentry->d_lock);