From: Ross Zwisler <ross.zwisler@linux.intel.com>
To: linux-kernel@vger.kernel.org
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>,
"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: [PATCH v3 3/6] ext4: Online defrag not supported with DAX
Date: Tue, 16 Feb 2016 20:34:16 -0700 [thread overview]
Message-ID: <1455680059-20126-4-git-send-email-ross.zwisler@linux.intel.com> (raw)
In-Reply-To: <1455680059-20126-1-git-send-email-ross.zwisler@linux.intel.com>
Online defrag operations for ext4 are hard coded to use the page cache.
See ext4_ioctl() -> ext4_move_extents() -> move_extent_per_page()
When combined with DAX I/O, which circumvents the page cache, this can
result in data corruption. This was observed with xfstests ext4/307 and
ext4/308.
Fix this by only allowing online defrag for non-DAX files.
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
---
fs/ext4/ioctl.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index 0f6c369..e32c86f 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -583,6 +583,11 @@ group_extend_out:
"Online defrag not supported with bigalloc");
err = -EOPNOTSUPP;
goto mext_out;
+ } else if (IS_DAX(inode)) {
+ ext4_msg(sb, KERN_ERR,
+ "Online defrag not supported with DAX");
+ err = -EOPNOTSUPP;
+ goto mext_out;
}
err = mnt_want_write_file(filp);
--
2.5.0
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next prev parent reply other threads:[~2016-02-17 3:34 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
2016-02-17 3:34 ` Ross Zwisler [this message]
2016-02-17 21:34 ` [PATCH v3 3/6] ext4: Online defrag not supported with DAX 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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