Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull vfs fixes from Al Viro.

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  posix_acl: de-union a_refcount and a_rcu
  nfs_atomic_open(): prevent parallel nfs_lookup() on a negative hashed
  Use the right predicate in ->atomic_open() instances

fs/9p/vfs_inode.c

@@ -853,7 +853,7 @@ v9fs_vfs_atomic_open(struct inode *dir, struct dentry *dentry,
 	struct p9_fid *fid, *inode_fid;
 	struct dentry *res = NULL;
 
-	if (d_unhashed(dentry)) {
+	if (d_in_lookup(dentry)) {
 		res = v9fs_vfs_lookup(dir, dentry, 0);
 		if (IS_ERR(res))
 			return PTR_ERR(res);

fs/9p/vfs_inode_dotl.c

@@ -254,7 +254,7 @@ v9fs_vfs_atomic_open_dotl(struct inode *dir, struct dentry *dentry,
 	struct posix_acl *pacl = NULL, *dacl = NULL;
 	struct dentry *res = NULL;
 
-	if (d_unhashed(dentry)) {
+	if (d_in_lookup(dentry)) {
 		res = v9fs_vfs_lookup(dir, dentry, 0);
 		if (IS_ERR(res))
 			return PTR_ERR(res);

fs/ceph/file.c

@@ -394,7 +394,7 @@ int ceph_atomic_open(struct inode *dir, struct dentry *dentry,
 	if ((flags & O_CREAT) && !req->r_reply_info.head->is_dentry)
 		err = ceph_handle_notrace_create(dir, dentry);
 
-	if (d_unhashed(dentry)) {
+	if (d_in_lookup(dentry)) {
 		dn = ceph_finish_lookup(req, dentry, err);
 		if (IS_ERR(dn))
 			err = PTR_ERR(dn);

fs/cifs/dir.c

@@ -445,7 +445,7 @@ cifs_atomic_open(struct inode *inode, struct dentry *direntry,
 		 * Check for hashed negative dentry. We have already revalidated
 		 * the dentry and it is fine. No need to perform another lookup.
 		 */
-		if (!d_unhashed(direntry))
+		if (!d_in_lookup(direntry))
 			return -ENOENT;
 
 		res = cifs_lookup(inode, direntry, 0);

fs/fuse/dir.c

@@ -480,7 +480,7 @@ static int fuse_atomic_open(struct inode *dir, struct dentry *entry,
 	struct fuse_conn *fc = get_fuse_conn(dir);
 	struct dentry *res = NULL;
 
-	if (d_unhashed(entry)) {
+	if (d_in_lookup(entry)) {
 		res = fuse_lookup(dir, entry, 0);
 		if (IS_ERR(res))
 			return PTR_ERR(res);

fs/gfs2/inode.c

@@ -1189,7 +1189,7 @@ static int gfs2_atomic_open(struct inode *dir, struct dentry *dentry,
 	struct dentry *d;
 	bool excl = !!(flags & O_EXCL);
 
-	if (!d_unhashed(dentry))
+	if (!d_in_lookup(dentry))
 		goto skip_lookup;
 
 	d = __gfs2_lookup(dir, dentry, file, opened);

fs/nfs/dir.c

@@ -1485,11 +1485,13 @@ int nfs_atomic_open(struct inode *dir, struct dentry *dentry,
 		    struct file *file, unsigned open_flags,
 		    umode_t mode, int *opened)
 {
+	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
 	struct nfs_open_context *ctx;
 	struct dentry *res;
 	struct iattr attr = { .ia_valid = ATTR_OPEN };
 	struct inode *inode;
 	unsigned int lookup_flags = 0;
+	bool switched = false;
 	int err;
 
 	/* Expect a negative dentry */
@@ -1504,7 +1506,7 @@ int nfs_atomic_open(struct inode *dir, struct dentry *dentry,
 
 	/* NFS only supports OPEN on regular files */
 	if ((open_flags & O_DIRECTORY)) {
-		if (!d_unhashed(dentry)) {
+		if (!d_in_lookup(dentry)) {
 			/*
 			 * Hashed negative dentry with O_DIRECTORY: dentry was
 			 * revalidated and is fine, no need to perform lookup
@@ -1528,6 +1530,17 @@ int nfs_atomic_open(struct inode *dir, struct dentry *dentry,
 		attr.ia_size = 0;
 	}
 
+	if (!(open_flags & O_CREAT) && !d_in_lookup(dentry)) {
+		d_drop(dentry);
+		switched = true;
+		dentry = d_alloc_parallel(dentry->d_parent,
+					  &dentry->d_name, &wq);
+		if (IS_ERR(dentry))
+			return PTR_ERR(dentry);
+		if (unlikely(!d_in_lookup(dentry)))
+			return finish_no_open(file, dentry);
+	}
+
 	ctx = create_nfs_open_context(dentry, open_flags);
 	err = PTR_ERR(ctx);
 	if (IS_ERR(ctx))
@@ -1563,14 +1576,23 @@ int nfs_atomic_open(struct inode *dir, struct dentry *dentry,
 	trace_nfs_atomic_open_exit(dir, ctx, open_flags, err);
 	put_nfs_open_context(ctx);
 out:
+	if (unlikely(switched)) {
+		d_lookup_done(dentry);
+		dput(dentry);
+	}
 	return err;
 
 no_open:
 	res = nfs_lookup(dir, dentry, lookup_flags);
-	err = PTR_ERR(res);
+	if (switched) {
+		d_lookup_done(dentry);
+		if (!res)
+			res = dentry;
+		else
+			dput(dentry);
+	}
 	if (IS_ERR(res))
-		goto out;
-
+		return PTR_ERR(res);
 	return finish_no_open(file, res);
 }
 EXPORT_SYMBOL_GPL(nfs_atomic_open);

include/linux/posix_acl.h

@@ -43,10 +43,8 @@ struct posix_acl_entry {
 };
 
 struct posix_acl {
-	union {
-		atomic_t		a_refcount;
-		struct rcu_head		a_rcu;
-	};
+	atomic_t		a_refcount;
+	struct rcu_head		a_rcu;
 	unsigned int		a_count;
 	struct posix_acl_entry	a_entries[0];
 };