From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f200.google.com (mail-pf0-f200.google.com [209.85.192.200]) by kanga.kvack.org (Postfix) with ESMTP id D0E596B0006 for ; Fri, 2 Mar 2018 14:15:45 -0500 (EST) Received: by mail-pf0-f200.google.com with SMTP id y20so5748975pfm.1 for ; Fri, 02 Mar 2018 11:15:45 -0800 (PST) Received: from mga14.intel.com (mga14.intel.com. [192.55.52.115]) by mx.google.com with ESMTPS id f1-v6si5234888plb.73.2018.03.02.11.15.43 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 02 Mar 2018 11:15:43 -0800 (PST) Subject: [PATCH v6] dax: introduce IS_DEVDAX() and IS_FSDAX() From: Dan Williams Date: Fri, 02 Mar 2018 11:06:36 -0800 Message-ID: <152001757529.22146.17936438768625217740.stgit@dwillia2-desk3.amr.corp.intel.com> In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: linux-nvdimm@lists.01.org Cc: Theodore Ts'o , Andreas Dilger , Alexander Viro , "Darrick J. Wong" , linux-xfs@vger.kernel.org, Matthew Wilcox , Ross Zwisler , stable@vger.kernel.org, Jan Kara Jan Kara , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.orglinux-xfs@vger.kernel.org The current IS_DAX() helper that checks if a file is in DAX mode serves two purposes. It is a control flow branch condition for DAX vs non-DAX paths and it is a mechanism to perform dead code elimination. The dead code elimination is required in the CONFIG_FS_DAX=n case since there are symbols in fs/dax.c that will be elided. While the dead code elimination can be addressed with nop stubs for the fs/dax.c symbols that does not address the need for a DAX control flow helper where fs/dax.c symbols are not involved. Moreover, the control flow changes, in some cases, need to be cognizant of whether the DAX file is a typical file or a Device-DAX special file. Introduce IS_DEVDAX() and IS_FSDAX() to simultaneously address the file-type control flow and dead-code elimination use cases. IS_DAX() will be deleted after all sites are converted to use the file-type specific helper. Note, this change is also a pre-requisite for fixing the definition of the S_DAX inode flag in the CONFIG_FS_DAX=n + CONFIG_DEV_DAX=y case. The flag needs to be defined, non-zero, if either DAX facility is enabled. Cc: "Theodore Ts'o" Cc: Andreas Dilger Cc: Alexander Viro Cc: "Darrick J. Wong" Cc: linux-xfs@vger.kernel.org Cc: Matthew Wilcox Cc: Ross Zwisler Cc: Fixes: dee410792419 ("/dev/dax, core: file operations and dax-mmap") Reported-by: Jan Kara Reviewed-by: Jan Kara Signed-off-by: Dan Williams --- Changes since v5: * add comments to clarify the S_ISCHR() checks (Darrick) include/linux/fs.h | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/include/linux/fs.h b/include/linux/fs.h index 79c413985305..751975b8b29b 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1909,6 +1909,30 @@ static inline bool sb_rdonly(const struct super_block *sb) { return sb->s_flags #define IS_WHITEOUT(inode) (S_ISCHR(inode->i_mode) && \ (inode)->i_rdev == WHITEOUT_DEV) +static inline bool IS_DEVDAX(struct inode *inode) +{ + if (!IS_ENABLED(CONFIG_DEV_DAX)) + return false; + if ((inode->i_flags & S_DAX) == 0) + return false; + /* regular files with S_DAX are filesystem-dax instances */ + if (!S_ISCHR(inode->i_mode)) + return false; + return true; +} + +static inline bool IS_FSDAX(struct inode *inode) +{ + if (!IS_ENABLED(CONFIG_FS_DAX)) + return false; + if ((inode->i_flags & S_DAX) == 0) + return false; + /* character devices with S_DAX are device-dax instances */ + if (S_ISCHR(inode->i_mode)) + return false; + return true; +} + static inline bool HAS_UNMAPPED_ID(struct inode *inode) { return !uid_valid(inode->i_uid) || !gid_valid(inode->i_gid); -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org