From patchwork Thu Aug 25 13:31:30 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Jeff Layton X-Patchwork-Id: 600343 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8F428C04AA5 for ; Thu, 25 Aug 2022 13:32:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242884AbiHYNcc (ORCPT ); Thu, 25 Aug 2022 09:32:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36500 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242729AbiHYNcF (ORCPT ); Thu, 25 Aug 2022 09:32:05 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6CA23B5A74 for ; Thu, 25 Aug 2022 06:31:55 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 589DA61D07 for ; Thu, 25 Aug 2022 13:31:54 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5018BC4347C; Thu, 25 Aug 2022 13:31:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1661434313; bh=QphBE616auSB+zZidkGpeODlEg1SAHOBw/o43+yc8Gw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=js2bxNkU3Qe+12KmGltXE2m4iTxCWzK7CDAw6vKRCig+UQ8Ope07OfD2VzFIX1+N9 E48xlj7XssbBKWdW1vTM8oQ43gZj0yH++n8mhntG7ozklmsqk5T82LJ0WHjkZJSXy/ kwrSo7iMTzgKwPgbgVLEeotREPRIBhmnvJ8UTz6SXMzAFmWVXmTlnB4/bOe3Y5sRoV lJNDwGdusyQ8uFhufXpfySKxs+HdUlBAcijHvDzxvb3i5qyoCeQKWF7lZBNXd52qiH BOevcrq//jB9HuEoMIS8MUkywPYk+X7E4i1b/WsUSeU1GcKQqoaHsMFsT56u15qjo2 YQi6GB2KiQB/A== From: Jeff Layton To: xiubli@redhat.com, idryomov@gmail.com Cc: lhenriques@suse.de, ceph-devel@vger.kernel.org Subject: [PATCH v15 27/29] ceph: update documentation regarding snapshot naming limitations Date: Thu, 25 Aug 2022 09:31:30 -0400 Message-Id: <20220825133132.153657-28-jlayton@kernel.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220825133132.153657-1-jlayton@kernel.org> References: <20220825133132.153657-1-jlayton@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: ceph-devel@vger.kernel.org From: Luís Henriques Signed-off-by: Luís Henriques Reviewed-by: Xiubo Li Signed-off-by: Jeff Layton --- Documentation/filesystems/ceph.rst | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/Documentation/filesystems/ceph.rst b/Documentation/filesystems/ceph.rst index 4942e018db85..d487cabe792d 100644 --- a/Documentation/filesystems/ceph.rst +++ b/Documentation/filesystems/ceph.rst @@ -57,6 +57,16 @@ a snapshot on any subdirectory (and its nested contents) in the system. Snapshot creation and deletion are as simple as 'mkdir .snap/foo' and 'rmdir .snap/foo'. +Snapshot names have two limitations: + +* They can not start with an underscore ('_'), as these names are reserved + for internal usage by the MDS. +* They can not exceed 240 characters in size. This is because the MDS makes + use of long snapshot names internally, which follow the format: + `__`. Since filenames in general can't have + more than 255 characters, and `` takes 13 characters, the long + snapshot names can take as much as 255 - 1 - 1 - 13 = 240. + Ceph also provides some recursive accounting on directories for nested files and bytes. That is, a 'getfattr -d foo' on any directory in the system will reveal the total number of nested regular files and