From: Jan Kara <jack@suse.cz>
To: Dan Williams <dan.j.williams@intel.com>
Cc: linux-nvdimm@lists.01.org, Theodore Ts'o <tytso@mit.edu>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
Matthew Wilcox <mawilcox@microsoft.com>,
linux-kernel@vger.kernel.org, stable@vger.kernel.org,
"supporter:XFS FILESYSTEM" <linux-xfs@vger.kernel.org>,
linux-mm@kvack.org, Andreas Dilger <adilger.kernel@dilger.ca>,
Alexander Viro <viro@zeniv.linux.org.uk>,
linux-fsdevel@vger.kernel.org, Jan Kara <jack@suse.cz>,
Ross Zwisler <ross.zwisler@linux.intel.com>
Subject: Re: [PATCH v4 02/12] dax: introduce IS_DEVDAX() and IS_FSDAX()
Date: Tue, 27 Feb 2018 17:54:49 +0100 [thread overview]
Message-ID: <20180227165449.abbhpu7gwqpxcqst@quack2.suse.cz> (raw)
In-Reply-To: <151970520551.26729.12707678649514382892.stgit@dwillia2-desk3.amr.corp.intel.com>
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 <jack@suse.cz>
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" <tytso@mit.edu>
> Cc: Andreas Dilger <adilger.kernel@dilger.ca>
> Cc: Alexander Viro <viro@zeniv.linux.org.uk>
> Cc: "Darrick J. Wong" <darrick.wong@oracle.com>
> Cc: linux-xfs@vger.kernel.org (supporter:XFS FILESYSTEM)
> Cc: Matthew Wilcox <mawilcox@microsoft.com>
> Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
> Cc: <stable@vger.kernel.org>
> Fixes: dee410792419 ("/dev/dax, core: file operations and dax-mmap")
> Reported-by: Jan Kara <jack@suse.cz>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
> 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 <jack@suse.com>
SUSE Labs, CR
next prev parent reply other threads:[~2018-02-27 16:54 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-27 4:19 [PATCH v4 00/12] vfio, dax: prevent long term filesystem-dax pins and other fixes Dan Williams
2018-02-27 4:20 ` [PATCH v4 01/12] dax: fix vma_is_fsdax() helper Dan Williams
2018-02-27 4:20 ` [PATCH v4 02/12] dax: introduce IS_DEVDAX() and IS_FSDAX() Dan Williams
2018-02-27 16:54 ` Jan Kara [this message]
2018-02-27 4:20 ` [PATCH v4 03/12] ext2, dax: finish implementing dax_sem helpers Dan Williams
2018-02-27 17:00 ` Jan Kara
2018-02-27 4:20 ` [PATCH v4 04/12] ext2, dax: define ext2_dax_*() infrastructure in all cases Dan Williams
2018-02-27 17:01 ` Jan Kara
2018-02-27 4:20 ` [PATCH v4 05/12] ext4, dax: define ext4_dax_*() " Dan Williams
2018-02-27 17:01 ` Jan Kara
2018-02-27 4:20 ` [PATCH v4 06/12] ext2, dax: replace IS_DAX() with IS_FSDAX() Dan Williams
2018-02-27 17:02 ` Jan Kara
2018-02-27 4:20 ` [PATCH v4 07/12] ext4, " Dan Williams
2018-02-27 17:02 ` Jan Kara
2018-02-27 4:20 ` [PATCH v4 08/12] xfs, " Dan Williams
2018-02-27 17:03 ` Jan Kara
2018-02-27 4:20 ` [PATCH v4 09/12] mm, dax: replace IS_DAX() with IS_DEVDAX() or IS_FSDAX() Dan Williams
2018-02-27 17:05 ` Jan Kara
2018-02-27 4:20 ` [PATCH v4 10/12] fs, dax: kill IS_DAX() Dan Williams
2018-02-27 17:06 ` Jan Kara
2018-02-27 4:20 ` [PATCH v4 11/12] dax: fix S_DAX definition Dan Williams
2018-02-27 4:20 ` [PATCH v4 12/12] vfio: disable filesystem-dax page pinning Dan Williams
2018-02-27 22:23 ` [PATCH v4 00/12] vfio, dax: prevent long term filesystem-dax pins and other fixes Dave Chinner
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