From: Jan Kara <jack@suse.cz>
To: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: linux-kernel@vger.kernel.org,
"J. Bruce Fields" <bfields@fieldses.org>,
Theodore Ts'o <tytso@mit.edu>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Andreas Dilger <adilger.kernel@dilger.ca>,
Andrew Morton <akpm@linux-foundation.org>,
Dan Williams <dan.j.williams@intel.com>,
Dave Chinner <david@fromorbit.com>, Jan Kara <jack@suse.com>,
Jeff Layton <jlayton@poochiereds.net>,
Jens Axboe <axboe@kernel.dk>,
Matthew Wilcox <willy@linux.intel.com>,
linux-block@vger.kernel.org, linux-ext4@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
linux-nvdimm@lists.01.org, xfs@oss.sgi.com
Subject: Re: [PATCH v3 2/6] ext2, ext4: only set S_DAX for regular inodes
Date: Wed, 17 Feb 2016 22:33:25 +0100 [thread overview]
Message-ID: <20160217213325.GH14140@quack.suse.cz> (raw)
In-Reply-To: <1455680059-20126-3-git-send-email-ross.zwisler@linux.intel.com>
On Tue 16-02-16 20:34:15, Ross Zwisler wrote:
> When S_DAX is set on an inode we assume that if there are pages attached
> to the mapping (mapping->nrpages != 0), those pages are clean zero pages
> that were used to service reads from holes. Any dirty data associated with
> the inode should be in the form of DAX exceptional entries
> (mapping->nrexceptional) that is written back via
> dax_writeback_mapping_range().
>
> With the current code, though, this isn't always true. For example, ext2
> and ext4 directory inodes can have S_DAX set, but have their dirty data
> stored as dirty page cache entries. For these types of inodes, having
> S_DAX set doesn't really make sense since their I/O doesn't actually happen
> through the DAX code path.
>
> Instead, only allow S_DAX to be set for regular inodes for ext2 and ext4.
> This allows us to have strict DAX vs non-DAX paths in the writeback code.
>
> Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Looks good. You can add:
Reviewed-by: Jan Kara <jack@suse.cz>
Honza
> ---
> fs/ext2/inode.c | 2 +-
> fs/ext4/inode.c | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
> index 338eefd..27e2cdd 100644
> --- a/fs/ext2/inode.c
> +++ b/fs/ext2/inode.c
> @@ -1296,7 +1296,7 @@ void ext2_set_inode_flags(struct inode *inode)
> inode->i_flags |= S_NOATIME;
> if (flags & EXT2_DIRSYNC_FL)
> inode->i_flags |= S_DIRSYNC;
> - if (test_opt(inode->i_sb, DAX))
> + if (test_opt(inode->i_sb, DAX) && S_ISREG(inode->i_mode))
> inode->i_flags |= S_DAX;
> }
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 83bc8bf..7088aa5 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -4127,7 +4127,7 @@ void ext4_set_inode_flags(struct inode *inode)
> new_fl |= S_NOATIME;
> if (flags & EXT4_DIRSYNC_FL)
> new_fl |= S_DIRSYNC;
> - if (test_opt(inode->i_sb, DAX))
> + if (test_opt(inode->i_sb, DAX) && S_ISREG(inode->i_mode))
> new_fl |= S_DAX;
> inode_set_flags(inode, new_fl,
> S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC|S_DAX);
> --
> 2.5.0
>
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
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next prev parent reply other threads:[~2016-02-17 21:33 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-17 3:34 [PATCH v3 0/6] DAX fixes, move flushing calls to FS Ross Zwisler
2016-02-17 3:34 ` [PATCH v3 1/6] block: disable block device DAX by default Ross Zwisler
2016-02-17 21:55 ` Jan Kara
2016-02-17 3:34 ` [PATCH v3 2/6] ext2, ext4: only set S_DAX for regular inodes Ross Zwisler
2016-02-17 21:33 ` Jan Kara [this message]
2016-02-17 3:34 ` [PATCH v3 3/6] ext4: Online defrag not supported with DAX Ross Zwisler
2016-02-17 21:34 ` Jan Kara
2016-02-17 21:50 ` Ross Zwisler
2016-02-17 22:10 ` Jan Kara
2016-02-18 0:12 ` Dave Chinner
2016-02-17 3:34 ` [PATCH v3 4/6] dax: give DAX clearing code correct bdev Ross Zwisler
2016-02-17 21:37 ` Jan Kara
2016-02-17 3:34 ` [PATCH v3 5/6] dax: move writeback calls into the filesystems Ross Zwisler
2016-02-17 3:34 ` [PATCH v3 6/6] block: use dax_do_io() if blkdev_dax_capable() Ross Zwisler
2016-02-17 21:54 ` Jan Kara
2016-02-17 22:18 ` Dan Williams
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