From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f72.google.com (mail-pg0-f72.google.com [74.125.83.72]) by kanga.kvack.org (Postfix) with ESMTP id 58FEB6B0006 for ; Tue, 27 Feb 2018 11:54:54 -0500 (EST) Received: by mail-pg0-f72.google.com with SMTP id v8so7162865pgs.9 for ; Tue, 27 Feb 2018 08:54:54 -0800 (PST) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id 9-v6si8742560ple.367.2018.02.27.08.54.52 for (version=TLS1 cipher=AES128-SHA bits=128/128); Tue, 27 Feb 2018 08:54:53 -0800 (PST) Date: Tue, 27 Feb 2018 17:54:49 +0100 From: Jan Kara Subject: Re: [PATCH v4 02/12] dax: introduce IS_DEVDAX() and IS_FSDAX() Message-ID: <20180227165449.abbhpu7gwqpxcqst@quack2.suse.cz> References: <151970519370.26729.1011551137381425076.stgit@dwillia2-desk3.amr.corp.intel.com> <151970520551.26729.12707678649514382892.stgit@dwillia2-desk3.amr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <151970520551.26729.12707678649514382892.stgit@dwillia2-desk3.amr.corp.intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: Dan Williams Cc: linux-nvdimm@lists.01.org, Theodore Ts'o , "Darrick J. Wong" , Matthew Wilcox , linux-kernel@vger.kernel.org, stable@vger.kernel.org, "supporter:XFS FILESYSTEM" , linux-mm@kvack.org, Andreas Dilger , Alexander Viro , linux-fsdevel@vger.kernel.org, Jan Kara , Ross Zwisler On Mon 26-02-18 20:20:05, Dan Williams wrote: > The current IS_DAX() helper that checks the S_DAX inode flag is > ambiguous, and currently has the broken assumption that the S_DAX flag I don't think S_DAX flag is really ambiguous. It is just that in CONFIG_FS_DAX=n + CONFIG_DEV_DAX=y case, the compiler is not able to figure out some calls behind IS_DAX() are dead code and so the kernel won't compile / link. Or is there any other problem I'm missing? If I'm indeed right, then please tell this in the changelog and don't talk about abstract ambiguity of S_DAX flag. As much as I'd prefer to solve link-time problems with stubs instead of relying on dead-code elimination, I can live with split macros so once the changelog is settled, feel free to add: Reviewed-by: Jan Kara Honza > is only non-zero in the CONFIG_FS_DAX=y case. In preparation for > defining S_DAX to non-zero in the CONFIG_FS_DAX=n + CONFIG_DEV_DAX=y > case, introduce two explicit helpers to replace IS_DAX(). > > Cc: "Theodore Ts'o" > Cc: Andreas Dilger > Cc: Alexander Viro > Cc: "Darrick J. Wong" > Cc: linux-xfs@vger.kernel.org (supporter:XFS FILESYSTEM) > Cc: Matthew Wilcox > Cc: Ross Zwisler > Cc: > Fixes: dee410792419 ("/dev/dax, core: file operations and dax-mmap") > Reported-by: Jan Kara > Signed-off-by: Dan Williams > --- > include/linux/fs.h | 22 ++++++++++++++++++++++ > 1 file changed, 22 insertions(+) > > diff --git a/include/linux/fs.h b/include/linux/fs.h > index 79c413985305..bd0c46880572 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -1909,6 +1909,28 @@ 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; > + 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; > + 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); > -- Jan Kara SUSE Labs, CR -- 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