From: Ross Zwisler <ross.zwisler@linux.intel.com>
To: linux-kernel@vger.kernel.org
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>,
"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>,
Matthew Wilcox <willy@linux.intel.com>,
linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-mm@kvack.org, linux-nvdimm@ml01.01.org, xfs@oss.sgi.com
Subject: [PATCH v2 0/2] DAX bdev fixes - move flushing calls to FS
Date: Wed, 10 Feb 2016 13:48:54 -0700 [thread overview]
Message-ID: <1455137336-28720-1-git-send-email-ross.zwisler@linux.intel.com> (raw)
During testing of raw block devices + DAX I noticed that the struct
block_device that we were using for DAX operations was incorrect. For the
fault handlers, etc. we can just get the correct bdev via get_block(),
which is passed in as a function pointer, but for the *sync code and for
sector zeroing we don't have access to get_block(). This is also an issue
for XFS real-time devices, whenever we get those working.
Patch one of this series fixes the DAX sector zeroing code by explicitly
passing in a valid struct block_device.
Patch two of this series fixes DAX *sync support by moving calls to
dax_writeback_mapping_range() out of filemap_write_and_wait_range() and
into the filesystem/block device ->writepages function so that it can
supply us with a valid block device. This also fixes DAX code to properly
flush caches in response to sync(2).
Thanks to Jan Kara for his initial draft of patch 2:
https://lkml.org/lkml/2016/2/9/485
Here are the changes that I've made to that patch:
1) For DAX mappings, only return after calling
dax_writeback_mapping_range() if we encountered an error. In the non-error
case we still need to write back normal pages, else we lose metadata
updates.
2) In dax_writeback_mapping_range(), move the new check for
if (!mapping->nrexceptional || wbc->sync_mode != WB_SYNC_ALL)
above the i_blkbits check. In my testing I found cases where
dax_writeback_mapping_range() was called for inodes with i_blkbits !=
PAGE_SHIFT - I'm assuming these are internal metadata inodes? They have no
exceptional DAX entries to flush, so we have no work to do, but if we
return error from the i_blkbits check we will fail the overall writeback
operation. Please let me know if it seems wrong for us to be seeing inodes
set to use DAX but with i_blkbits != PAGE_SHIFT and I'll get more info.
3) In filemap_write_and_wait() and filemap_write_and_wait_range(), continue
the writeback in the case that DAX is enabled but we only have a nonzero
mapping->nrpages. As with 1) and 2), I believe this is necessary to
properly writeback metadata changes. If this sounds wrong, please let me
know and I'll get more info.
A working tree can be found here:
https://git.kernel.org/cgit/linux/kernel/git/zwisler/linux.git/log/?h=fsync_bdev_v2
Ross Zwisler (2):
dax: supply DAX clearing code with correct bdev
dax: move writeback calls into the filesystems
fs/block_dev.c | 16 +++++++++++++++-
fs/dax.c | 22 ++++++++++++----------
fs/ext2/inode.c | 17 +++++++++++++++--
fs/ext4/inode.c | 7 +++++++
fs/xfs/xfs_aops.c | 11 ++++++++++-
fs/xfs/xfs_aops.h | 1 +
fs/xfs/xfs_bmap_util.c | 3 ++-
include/linux/dax.h | 8 +++++---
mm/filemap.c | 12 ++++--------
9 files changed, 71 insertions(+), 26 deletions(-)
--
2.5.0
next reply other threads:[~2016-02-10 20:49 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-10 20:48 Ross Zwisler [this message]
2016-02-10 20:48 ` [PATCH v2 1/2] dax: supply DAX clearing code with correct bdev Ross Zwisler
2016-02-10 20:48 ` [PATCH v2 2/2] dax: move writeback calls into the filesystems Ross Zwisler
2016-02-10 22:03 ` Dave Chinner
2016-02-10 22:43 ` Ross Zwisler
2016-02-10 23:44 ` Dave Chinner
2016-02-11 12:50 ` Jan Kara
2016-02-11 15:22 ` Dan Williams
2016-02-11 16:22 ` Jan Kara
2016-02-11 20:46 ` Dave Chinner
2016-02-11 20:58 ` Dan Williams
2016-02-11 22:46 ` Dave Chinner
2016-02-11 22:59 ` Dan Williams
2016-02-11 23:44 ` Dave Chinner
2016-02-11 12:43 ` [PATCH v2 0/2] DAX bdev fixes - move flushing calls to FS Jan Kara
2016-02-11 19:49 ` Ross Zwisler
2016-02-11 20:50 ` Dave Chinner
2016-02-12 19:03 ` Ross Zwisler
2016-02-13 2:38 ` Dave Chinner
2016-02-13 4:59 ` Ross Zwisler
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