From: Jan Kara <jack@suse.cz>
To: ira.weiny@intel.com
Cc: linux-ext4@vger.kernel.org,
Andreas Dilger <adilger.kernel@dilger.ca>,
"Theodore Y. Ts'o" <tytso@mit.edu>, Jan Kara <jack@suse.cz>,
Eric Biggers <ebiggers@kernel.org>,
Al Viro <viro@zeniv.linux.org.uk>,
Dan Williams <dan.j.williams@intel.com>,
Dave Chinner <david@fromorbit.com>,
Christoph Hellwig <hch@lst.de>, Jeff Moyer <jmoyer@redhat.com>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH V3 4/8] fs/ext4: Update ext4_should_use_dax()
Date: Wed, 20 May 2020 15:37:28 +0200 [thread overview]
Message-ID: <20200520133728.GD30597@quack2.suse.cz> (raw)
In-Reply-To: <20200520055753.3733520-5-ira.weiny@intel.com>
On Tue 19-05-20 22:57:49, ira.weiny@intel.com wrote:
> From: Ira Weiny <ira.weiny@intel.com>
>
> S_DAX should only be enabled when the underlying block device supports
> dax.
>
> Change ext4_should_use_dax() to check for device support prior to the
> over riding mount option.
>
> While we are at it change the function to ext4_should_enable_dax() as
> this better reflects the ask as well as matches xfs.
>
> Reviewed-by: Jan Kara <jack@suse.cz>
> Signed-off-by: Ira Weiny <ira.weiny@intel.com>
...
> @@ -4412,7 +4410,13 @@ static bool ext4_should_use_dax(struct inode *inode)
> return false;
> if (ext4_test_inode_flag(inode, EXT4_INODE_VERITY))
> return false;
> - return true;
> + if (!bdev_dax_supported(inode->i_sb->s_bdev,
> + inode->i_sb->s_blocksize))
> + return false;
> + if (test_opt(inode->i_sb, DAX_ALWAYS))
> + return true;
> +
> + return false;
> }
Now that I think about it - shouldn't we rather cache the result of
bdev_dax_supported() in sb on mount and then just check the flag here?
Because bdev_dax_supported() isn't exactly cheap (it does a lot of checks
and mappings, tries to read from the pmem, ...).
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
next prev parent reply other threads:[~2020-05-20 13:37 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-20 5:57 [PATCH V3 0/8] Enable ext4 support for per-file/directory DAX operations ira.weiny
2020-05-20 5:57 ` [PATCH V3 1/8] fs/ext4: Narrow scope of DAX check in setflags ira.weiny
2020-05-20 5:57 ` [PATCH V3 2/8] fs/ext4: Disallow verity if inode is DAX ira.weiny
2020-05-20 5:57 ` [PATCH V3 3/8] fs/ext4: Change EXT4_MOUNT_DAX to EXT4_MOUNT_DAX_ALWAYS ira.weiny
2020-05-20 5:57 ` [PATCH V3 4/8] fs/ext4: Update ext4_should_use_dax() ira.weiny
2020-05-20 13:37 ` Jan Kara [this message]
2020-05-20 19:40 ` Ira Weiny
2020-05-21 10:24 ` Jan Kara
2020-05-20 5:57 ` [PATCH V3 5/8] fs/ext4: Only change S_DAX on inode load ira.weiny
2020-05-20 5:57 ` [PATCH V3 6/8] fs/ext4: Make DAX mount option a tri-state ira.weiny
2020-05-20 5:57 ` [PATCH V3 7/8] fs/ext4: Introduce DAX inode flag ira.weiny
2020-05-20 14:11 ` Jan Kara
2020-05-20 18:34 ` Ira Weiny
2020-05-20 19:26 ` Andreas Dilger
2020-05-20 20:02 ` Ira Weiny
2020-05-20 20:55 ` Darrick J. Wong
2020-05-21 0:57 ` Andreas Dilger
2020-05-20 5:57 ` [PATCH V3 8/8] Documentation/dax: Update DAX enablement for ext4 ira.weiny
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