btrfs: Use xattr handler infrastructure

Use the VFS xattr handler infrastructure and get rid of similar code in
the filesystem.

Signed-off-by: Andreas Gruenbacher <[e-mail]>
Reviewed-by: David Sterba <[e-mail]>
Signed-off-by: Al Viro <[e-mail]>

fs/btrfs/inode.c

···
 	.setattr	= btrfs_setattr,
 	.mknod		= btrfs_mknod,
 	.setxattr	= btrfs_setxattr,
-	.getxattr	= btrfs_getxattr,
+	.getxattr	= generic_getxattr,
 	.listxattr	= btrfs_listxattr,
 	.removexattr	= btrfs_removexattr,
 	.permission	= btrfs_permission,
···
 	.getattr	= btrfs_getattr,
 	.setattr	= btrfs_setattr,
 	.setxattr	= btrfs_setxattr,
-	.getxattr	= btrfs_getxattr,
+	.getxattr	= generic_getxattr,
 	.listxattr      = btrfs_listxattr,
 	.removexattr	= btrfs_removexattr,
 	.permission	= btrfs_permission,
···
 	.setattr	= btrfs_setattr,
 	.permission	= btrfs_permission,
 	.setxattr	= btrfs_setxattr,
-	.getxattr	= btrfs_getxattr,
+	.getxattr	= generic_getxattr,
 	.listxattr	= btrfs_listxattr,
 	.removexattr	= btrfs_removexattr,
 	.get_acl	= btrfs_get_acl,
···
 	.setattr	= btrfs_setattr,
 	.permission	= btrfs_permission,
 	.setxattr	= btrfs_setxattr,
-	.getxattr	= btrfs_getxattr,
+	.getxattr	= generic_getxattr,
 	.listxattr	= btrfs_listxattr,
 	.removexattr	= btrfs_removexattr,
 	.update_time	= btrfs_update_time,

fs/btrfs/xattr.c

···
 	return ret;
 }
 
-/*
- * List of handlers for synthetic system.* attributes.  All real ondisk
- * attributes are handled directly.
- */
+static int btrfs_xattr_handler_get(const struct xattr_handler *handler,
+				   struct dentry *dentry, const char *name,
+				   void *buffer, size_t size)
+{
+	struct inode *inode = d_inode(dentry);
+
+	name = xattr_full_name(handler, name);
+	return __btrfs_getxattr(inode, name, buffer, size);
+}
+
+static int btrfs_xattr_handler_set(const struct xattr_handler *handler,
+				   struct dentry *dentry, const char *name,
+				   const void *buffer, size_t size,
+				   int flags)
+{
+	struct inode *inode = d_inode(dentry);
+
+	name = xattr_full_name(handler, name);
+	return __btrfs_setxattr(NULL, inode, name, buffer, size, flags);
+}
+
+static int btrfs_xattr_handler_set_prop(const struct xattr_handler *handler,
+					struct dentry *dentry,
+					const char *name, const void *value,
+					size_t size, int flags)
+{
+	name = xattr_full_name(handler, name);
+	return btrfs_set_prop(d_inode(dentry), name, value, size, flags);
+}
+
+static const struct xattr_handler btrfs_security_xattr_handler = {
+	.prefix = XATTR_SECURITY_PREFIX,
+	.get = btrfs_xattr_handler_get,
+	.set = btrfs_xattr_handler_set,
+};
+
+static const struct xattr_handler btrfs_trusted_xattr_handler = {
+	.prefix = XATTR_TRUSTED_PREFIX,
+	.get = btrfs_xattr_handler_get,
+	.set = btrfs_xattr_handler_set,
+};
+
+static const struct xattr_handler btrfs_user_xattr_handler = {
+	.prefix = XATTR_USER_PREFIX,
+	.get = btrfs_xattr_handler_get,
+	.set = btrfs_xattr_handler_set,
+};
+
+static const struct xattr_handler btrfs_btrfs_xattr_handler = {
+	.prefix = XATTR_BTRFS_PREFIX,
+	.get = btrfs_xattr_handler_get,
+	.set = btrfs_xattr_handler_set_prop,
+};
+
 const struct xattr_handler *btrfs_xattr_handlers[] = {
+	&btrfs_security_xattr_handler,
 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
 	&posix_acl_access_xattr_handler,
 	&posix_acl_default_xattr_handler,
 #endif
+	&btrfs_trusted_xattr_handler,
+	&btrfs_user_xattr_handler,
+	&btrfs_btrfs_xattr_handler,
 	NULL,
 };
-
-/*
- * Check if the attribute is in a supported namespace.
- *
- * This is applied after the check for the synthetic attributes in the system
- * namespace.
- */
-static int btrfs_is_valid_xattr(const char *name)
-{
-	int len = strlen(name);
-	int prefixlen = 0;
-
-	if (!strncmp(name, XATTR_SECURITY_PREFIX,
-			XATTR_SECURITY_PREFIX_LEN))
-		prefixlen = XATTR_SECURITY_PREFIX_LEN;
-	else if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
-		prefixlen = XATTR_SYSTEM_PREFIX_LEN;
-	else if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN))
-		prefixlen = XATTR_TRUSTED_PREFIX_LEN;
-	else if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN))
-		prefixlen = XATTR_USER_PREFIX_LEN;
-	else if (!strncmp(name, XATTR_BTRFS_PREFIX, XATTR_BTRFS_PREFIX_LEN))
-		prefixlen = XATTR_BTRFS_PREFIX_LEN;
-	else
-		return -EOPNOTSUPP;
-
-	/*
-	 * The name cannot consist of just prefix
-	 */
-	if (len <= prefixlen)
-		return -EINVAL;
-
-	return 0;
-}
-
-ssize_t btrfs_getxattr(struct dentry *dentry, const char *name,
-		       void *buffer, size_t size)
-{
-	int ret;
-
-	/*
-	 * If this is a request for a synthetic attribute in the system.*
-	 * namespace use the generic infrastructure to resolve a handler
-	 * for it via sb->s_xattr.
-	 */
-	if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
-		return generic_getxattr(dentry, name, buffer, size);
-
-	ret = btrfs_is_valid_xattr(name);
-	if (ret)
-		return ret;
-	return __btrfs_getxattr(d_inode(dentry), name, buffer, size);
-}
 
 int btrfs_setxattr(struct dentry *dentry, const char *name, const void *value,
 		   size_t size, int flags)
 {
 	struct btrfs_root *root = BTRFS_I(d_inode(dentry))->root;
-	int ret;
 
-	/*
-	 * The permission on security.* and system.* is not checked
-	 * in permission().
-	 */
 	if (btrfs_root_readonly(root))
 		return -EROFS;
-
-	/*
-	 * If this is a request for a synthetic attribute in the system.*
-	 * namespace use the generic infrastructure to resolve a handler
-	 * for it via sb->s_xattr.
-	 */
-	if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
-		return generic_setxattr(dentry, name, value, size, flags);
-
-	ret = btrfs_is_valid_xattr(name);
-	if (ret)
-		return ret;
-
-	if (!strncmp(name, XATTR_BTRFS_PREFIX, XATTR_BTRFS_PREFIX_LEN))
-		return btrfs_set_prop(d_inode(dentry), name,
-				      value, size, flags);
-
-	if (size == 0)
-		value = "";  /* empty EA, do not remove */
-
-	return __btrfs_setxattr(NULL, d_inode(dentry), name, value, size,
-				flags);
+	return generic_setxattr(dentry, name, value, size, flags);
 }
 
 int btrfs_removexattr(struct dentry *dentry, const char *name)
 {
 	struct btrfs_root *root = BTRFS_I(d_inode(dentry))->root;
-	int ret;
 
-	/*
-	 * The permission on security.* and system.* is not checked
-	 * in permission().
-	 */
 	if (btrfs_root_readonly(root))
 		return -EROFS;
-
-	/*
-	 * If this is a request for a synthetic attribute in the system.*
-	 * namespace use the generic infrastructure to resolve a handler
-	 * for it via sb->s_xattr.
-	 */
-	if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
-		return generic_removexattr(dentry, name);
-
-	ret = btrfs_is_valid_xattr(name);
-	if (ret)
-		return ret;
-
-	if (!strncmp(name, XATTR_BTRFS_PREFIX, XATTR_BTRFS_PREFIX_LEN))
-		return btrfs_set_prop(d_inode(dentry), name,
-				      NULL, 0, XATTR_REPLACE);
-
-	return __btrfs_setxattr(NULL, d_inode(dentry), name, NULL, 0,
-				XATTR_REPLACE);
+	return generic_removexattr(dentry, name);
 }
 
 static int btrfs_initxattrs(struct inode *inode,

fs/btrfs/xattr.h

···
 extern int __btrfs_setxattr(struct btrfs_trans_handle *trans,
 			    struct inode *inode, const char *name,
 			    const void *value, size_t size, int flags);
-extern ssize_t btrfs_getxattr(struct dentry *dentry, const char *name,
-		void *buffer, size_t size);
 extern int btrfs_setxattr(struct dentry *dentry, const char *name,
 		const void *value, size_t size, int flags);
 extern int btrfs_removexattr(struct dentry *dentry, const char *name);