From mboxrd@z Thu Jan 1 00:00:00 1970 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 7AAAFC433F5 for ; Wed, 27 Apr 2022 19:18:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233943AbiD0TVM (ORCPT ); Wed, 27 Apr 2022 15:21:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41594 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233208AbiD0TTm (ORCPT ); Wed, 27 Apr 2022 15:19:42 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A87F95D183 for ; Wed, 27 Apr 2022 12:14:03 -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 ams.source.kernel.org (Postfix) with ESMTPS id 5D949B82929 for ; Wed, 27 Apr 2022 19:14:02 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B3908C385AE; Wed, 27 Apr 2022 19:14:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1651086841; bh=raSOQ85s4gmZ5kxFMiAqoYCsC3yg08k/WbfEHPhmToE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pgBOEVac5rtVLTcTJfPPci3egzcGWuwBFOcT4ft5Q5X6RjxAQwTj0i/tX62o+fDz+ xQYUJorkh784R+vQnxdh5/u4qUH+b+F6wwbgzd7kbmOdz3EDhziQ4TAb9iy4eTjN/B aVIf/+3C7MZhrSgvFAdN3eaty5srBBCrOnALnRvu6XMV8rSmPOjPNH7slBDsTAzti0 ZSbKdcbowN8sW26pB1fwIND78ZNHawV3yUgmw4Yg2oHW3uXqscMDNz0DkERgcgI0bA zqH0fXKrMHw+jcEG6vRS7iqMDelIRWY2ukNysia19KXTfTju1w5LNhiArqlfXSZtV/ 9Bx0szUGdmGWw== From: Jeff Layton To: ceph-devel@vger.kernel.org Cc: xiubli@redhat.com, lhenriques@suse.de, idryomov@gmail.com Subject: [PATCH v14 63/64] ceph: update documentation regarding snapshot naming limitations Date: Wed, 27 Apr 2022 15:13:13 -0400 Message-Id: <20220427191314.222867-64-jlayton@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220427191314.222867-1-jlayton@kernel.org> References: <20220427191314.222867-1-jlayton@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: ceph-devel@vger.kernel.org From: Luís Henriques Reviewed-by: Xiubo Li Signed-off-by: Luís Henriques 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 -- 2.35.1