posix_acl: Add set_posix_acl

BugLink: http://bugs.launchpad.net/bugs/1607404

commit 485e71e8 upstream.

Factor out part of posix_acl_xattr_set into a common function that takes
a posix_acl, which nfsd can also call.

The prototype already exists in include/linux/posix_acl.h.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>

fs/posix_acl.c

@@ -806,6 +806,28 @@ posix_acl_xattr_get(const struct xattr_handler *handler,
 	return error;
 }
 
+int
+set_posix_acl(struct inode *inode, int type, struct posix_acl *acl)
+{
+	if (!IS_POSIXACL(inode))
+		return -EOPNOTSUPP;
+	if (!inode->i_op->set_acl)
+		return -EOPNOTSUPP;
+
+	if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
+		return acl ? -EACCES : 0;
+	if (!inode_owner_or_capable(inode))
+		return -EPERM;
+
+	if (acl) {
+		int ret = posix_acl_valid(acl);
+		if (ret)
+			return ret;
+	}
+	return inode->i_op->set_acl(inode, acl, type);
+}
+EXPORT_SYMBOL(set_posix_acl);
+
 static int
 posix_acl_xattr_set(const struct xattr_handler *handler,
 		    struct dentry *dentry, const char *name,
@@ -817,31 +839,14 @@ posix_acl_xattr_set(const struct xattr_handler *handler,
 
 	if (strcmp(name, "") != 0)
 		return -EINVAL;
-	if (!IS_POSIXACL(inode))
-		return -EOPNOTSUPP;
-	if (!inode->i_op->set_acl)
-		return -EOPNOTSUPP;
-
-	if (handler->flags == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
-		return value ? -EACCES : 0;
-	if (!inode_owner_or_capable(inode))
-		return -EPERM;
 
 	if (value) {
 		acl = posix_acl_from_xattr(dentry->d_sb->s_user_ns, value,
 					   size);
 		if (IS_ERR(acl))
 			return PTR_ERR(acl);
-
-		if (acl) {
-			ret = posix_acl_valid(acl);
-			if (ret)
-				goto out;
-		}
 	}
-
-	ret = inode->i_op->set_acl(inode, acl, handler->flags);
-out:
+	ret = set_posix_acl(inode, handler->flags, acl);
 	posix_acl_release(acl);
 	return ret;
 }