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 X-Spam-Level: X-Spam-Status: No, score=-11.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4C344C43465 for ; Mon, 21 Sep 2020 02:15:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 07F7C2073A for ; Mon, 21 Sep 2020 02:15:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726236AbgIUCPe (ORCPT ); Sun, 20 Sep 2020 22:15:34 -0400 Received: from mail.cn.fujitsu.com ([183.91.158.132]:33529 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726221AbgIUCPe (ORCPT ); Sun, 20 Sep 2020 22:15:34 -0400 X-IronPort-AV: E=Sophos;i="5.77,284,1596470400"; d="scan'208";a="99448158" Received: from unknown (HELO cn.fujitsu.com) ([10.167.33.5]) by heian.cn.fujitsu.com with ESMTP; 21 Sep 2020 10:15:31 +0800 Received: from G08CNEXMBPEKD06.g08.fujitsu.local (unknown [10.167.33.206]) by cn.fujitsu.com (Postfix) with ESMTP id 90B2748990CB; Mon, 21 Sep 2020 10:15:30 +0800 (CST) Received: from [10.167.220.69] (10.167.220.69) by G08CNEXMBPEKD06.g08.fujitsu.local (10.167.33.206) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Mon, 21 Sep 2020 10:15:27 +0800 Message-ID: <5F680CC0.4010200@cn.fujitsu.com> Date: Mon, 21 Sep 2020 10:15:28 +0800 From: Xiao Yang User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.2; zh-CN; rv:1.9.2.18) Gecko/20110616 Thunderbird/3.1.11 MIME-Version: 1.0 To: Ira Weiny CC: "darrick.wong@oracle.com" , "tytso@mit.edu" , "ebiggers@kernel.org" , "linux-ext4@vger.kernel.org" Subject: Re: [PATCH v2] chattr/lsattr: Support dax attribute References: <20200728053321.12892-1-yangx.jy@cn.fujitsu.com> <20200918005238.GC2541163@iweiny-DESK2.sc.intel.com> In-Reply-To: <20200918005238.GC2541163@iweiny-DESK2.sc.intel.com> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.167.220.69] X-ClientProxiedBy: G08CNEXCHPEKD06.g08.fujitsu.local (10.167.33.205) To G08CNEXMBPEKD06.g08.fujitsu.local (10.167.33.206) X-yoursite-MailScanner-ID: 90B2748990CB.A96E5 X-yoursite-MailScanner: Found to be clean X-yoursite-MailScanner-From: yangx.jy@cn.fujitsu.com Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On 2020/9/18 8:52, Ira Weiny wrote: > On Mon, Jul 27, 2020 at 10:33:21PM -0700, Xiao Yang wrote: >> Use the letter 'x' to set/get dax attribute on a directory/file. > This may allow the flag to be set but I don't think this implements the logic > within ext2 to properly support the flag does it? Hi Ira, In ext2, the dax flag cannot be set because ext2_ioctl() uses EXT2_FL_USER_MODIFIABLE to drop the unsupported flag. > Just a quick look shows that ext2_ioctl() does not have any dax checks in it > and you don't add them here? The dax flag never be passed into ext2 actually so I don't think we need some dax checks. > So how does this work? Does ext2 share all the code with ext4 to make it work? 1) ext2 without CONFIG_EXT4_USE_FOR_EXT2 unsupports the dax flag and ignores it sliently. 2) ext2 with CONFIG_EXT4_USE_FOR_EXT2 supports the dax flag. Thanks, Xiao Yang > Ira > >> Signed-off-by: Xiao Yang >> --- >> >> V1->V2: >> 1) Define FS_DAX_FL in order and add missing 'x' letter in manpage. >> 2) Add more detailed description about 'x' attribute. >> 3) 'x' is a separate attribute and doesn't always affect S_DAX(i.e. >> pagecache bypass) so remove the related info. >> >> lib/e2p/pf.c | 1 + >> lib/ext2fs/ext2_fs.h | 1 + >> misc/chattr.1.in | 15 ++++++++++++--- >> misc/chattr.c | 3 ++- >> 4 files changed, 16 insertions(+), 4 deletions(-) >> >> diff --git a/lib/e2p/pf.c b/lib/e2p/pf.c >> index 0c6998c4..e59cccff 100644 >> --- a/lib/e2p/pf.c >> +++ b/lib/e2p/pf.c >> @@ -44,6 +44,7 @@ static struct flags_name flags_array[] = { >> { EXT2_TOPDIR_FL, "T", "Top_of_Directory_Hierarchies" }, >> { EXT4_EXTENTS_FL, "e", "Extents" }, >> { FS_NOCOW_FL, "C", "No_COW" }, >> + { FS_DAX_FL, "x", "Dax" }, >> { EXT4_CASEFOLD_FL, "F", "Casefold" }, >> { EXT4_INLINE_DATA_FL, "N", "Inline_Data" }, >> { EXT4_PROJINHERIT_FL, "P", "Project_Hierarchy" }, >> diff --git a/lib/ext2fs/ext2_fs.h b/lib/ext2fs/ext2_fs.h >> index 6c20ea77..88f510a3 100644 >> --- a/lib/ext2fs/ext2_fs.h >> +++ b/lib/ext2fs/ext2_fs.h >> @@ -335,6 +335,7 @@ struct ext2_dx_tail { >> /* EXT4_EOFBLOCKS_FL 0x00400000 was here */ >> #define FS_NOCOW_FL 0x00800000 /* Do not cow file */ >> #define EXT4_SNAPFILE_FL 0x01000000 /* Inode is a snapshot */ >> +#define FS_DAX_FL 0x02000000 /* Inode is DAX */ >> #define EXT4_SNAPFILE_DELETED_FL 0x04000000 /* Snapshot is being deleted */ >> #define EXT4_SNAPFILE_SHRUNK_FL 0x08000000 /* Snapshot shrink has completed */ >> #define EXT4_INLINE_DATA_FL 0x10000000 /* Inode has inline data */ >> diff --git a/misc/chattr.1.in b/misc/chattr.1.in >> index ff2fcf00..5a4928a5 100644 >> --- a/misc/chattr.1.in >> +++ b/misc/chattr.1.in >> @@ -23,13 +23,13 @@ chattr \- change file attributes on a Linux file system >> .B chattr >> changes the file attributes on a Linux file system. >> .PP >> -The format of a symbolic mode is +-=[aAcCdDeFijPsStTu]. >> +The format of a symbolic mode is +-=[aAcCdDeFijPsStTux]. >> .PP >> The operator '+' causes the selected attributes to be added to the >> existing attributes of the files; '-' causes them to be removed; and '=' >> causes them to be the only attributes that the files have. >> .PP >> -The letters 'aAcCdDeFijPsStTu' select the new attributes for the files: >> +The letters 'aAcCdDeFijPsStTux' select the new attributes for the files: >> append only (a), >> no atime updates (A), >> compressed (c), >> @@ -45,7 +45,8 @@ secure deletion (s), >> synchronous updates (S), >> no tail-merging (t), >> top of directory hierarchy (T), >> -and undeletable (u). >> +undeletable (u), >> +and direct access for files (x). >> .PP >> The following attributes are read-only, and may be listed by >> .BR lsattr (1) >> @@ -210,6 +211,14 @@ saved. This allows the user to ask for its undeletion. Note: please >> make sure to read the bugs and limitations section at the end of this >> document. >> .TP >> +.B x >> +The 'x' attribute can be set on a directory or file. If the attribute >> +is set on an existing directory, it will be inherited by all files and >> +subdirectories that are subsequently created in the directory. If an >> +existing directory has contained some files and subdirectories, modifying >> +the attribute on the parent directory doesn't change the attributes on >> +these files and subdirectories. >> +.TP >> .B V >> A file with the 'V' attribute set has fs-verity enabled. It cannot be >> written to, and the filesystem will automatically verify all data read >> diff --git a/misc/chattr.c b/misc/chattr.c >> index a5d60170..c0337f86 100644 >> --- a/misc/chattr.c >> +++ b/misc/chattr.c >> @@ -86,7 +86,7 @@ static unsigned long sf; >> static void usage(void) >> { >> fprintf(stderr, >> - _("Usage: %s [-pRVf] [-+=aAcCdDeijPsStTuF] [-v version] files...\n"), >> + _("Usage: %s [-pRVf] [-+=aAcCdDeijPsStTuFx] [-v version] files...\n"), >> program_name); >> exit(1); >> } >> @@ -112,6 +112,7 @@ static const struct flags_char flags_array[] = { >> { EXT2_NOTAIL_FL, 't' }, >> { EXT2_TOPDIR_FL, 'T' }, >> { FS_NOCOW_FL, 'C' }, >> + { FS_DAX_FL, 'x' }, >> { EXT4_CASEFOLD_FL, 'F' }, >> { 0, 0 } >> }; >> -- >> 2.21.0 >> >> >> > > . >