From: Ross Zwisler <ross.zwisler@linux.intel.com>
To: Dave Chinner <david@fromorbit.com>
Cc: Matthew Wilcox <matthew.r.wilcox@intel.com>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-mm@kvack.org, linux-ext4@vger.kernel.org
Subject: Re: [PATCH v5 00/22] Rewrite XIP code and add XIP support to ext4
Date: Thu, 30 Jan 2014 22:45:26 -0700 (MST) [thread overview]
Message-ID: <alpine.OSX.2.00.1401302227450.29315@scrumpy> (raw)
In-Reply-To: <20140131030652.GK13997@dastard>
On Fri, 31 Jan 2014, Dave Chinner wrote:
> The read/write path is broken, Willy. We can't map arbitrary byte
> ranges to the DIO subsystem. I'm now certain that the data
> corruptions I'm seeing are in sub-sector regions from unaligned IOs
> from userspace. We still need to use the buffered IO path for non
> O_DIRECT IO to avoid these problems. I think I've worked out a way
> to short-circuit page cache lookups for the buffered IO path, so
> stay tuned....
Hi Dave,
I found an issue that would cause reads to return bad data earlier this week,
and sent a response to "[PATCH v5 22/22] XIP: Add support for unwritten
extents". Just wanted to make sure you're not running into that issue.
I'm also currently chasing a write corruption where we lose the data that we
had just written because ext4 thinks the portion of the extent we had just
written needs to be converted from an unwritten extent to a written extent, so
it clears the data to all zeros via:
xip_clear_blocks+0x53/0xd7
ext4_map_blocks+0x306/0x3d9 [ext4]
jbd2__journal_start+0xbd/0x188 [jbd2]
ext4_convert_unwritten_extents+0xf9/0x1ac [ext4]
ext4_direct_IO+0x2ca/0x3a5 [ext4]
This bug can be easily reproduced by fallocating an empty file up to a page,
and then writing into that page. The first write is essentially lost, and the
page remains all zeros. Subsequent writes succeed.
I'm still in the process of figuring out exactly why this is happening, but
unfortunately I won't be able to look at again until next week. I don't know
if it's related to the corruption that you're seeing or not, just wanted to
let you know.
- Ross
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next prev parent reply other threads:[~2014-01-31 5:45 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-16 1:24 [PATCH v5 00/22] Rewrite XIP code and add XIP support to ext4 Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 01/22] Fix XIP fault vs truncate race Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 02/22] Allow page fault handlers to perform the COW Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 03/22] axonram: Fix bug in direct_access Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 04/22] Change direct_access calling convention Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 05/22] Introduce IS_XIP(inode) Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 06/22] Treat XIP like O_DIRECT Matthew Wilcox
2014-01-31 16:59 ` Jan Kara
2014-01-16 1:24 ` [PATCH v5 07/22] Rewrite XIP page fault handling Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 08/22] Change xip_truncate_page to take a get_block parameter Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 09/22] Remove mm/filemap_xip.c Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 10/22] Remove get_xip_mem Matthew Wilcox
2014-01-16 1:46 ` Randy Dunlap
2014-01-27 13:26 ` Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 11/22] Replace ext2_clear_xip_target with xip_clear_blocks Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 12/22] ext2: Remove ext2_xip_verify_sb() Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 13/22] ext2: Remove ext2_use_xip Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 14/22] ext2: Remove xip.c and xip.h Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 15/22] Remove CONFIG_EXT2_FS_XIP Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 16/22] ext2: Remove ext2_aops_xip Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 17/22] xip: Add xip_zero_page_range Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 18/22] ext4: Make ext4_block_zero_page_range static Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 19/22] ext4: Add XIP functionality Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 20/22] ext4: Fix typos Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 21/22] xip: Add reporting of major faults Matthew Wilcox
2014-01-16 1:24 ` [PATCH v5 22/22] XIP: Add support for unwritten extents Matthew Wilcox
[not found] ` <CEFDA737.22F87%matthew.r.wilcox@intel.com>
2014-01-17 0:00 ` [PATCH v5 19/22] ext4: Add XIP functionality Ross Zwisler
[not found] ` <CEFD7DAD.22F65%matthew.r.wilcox@intel.com>
2014-01-22 22:51 ` [PATCH v5 22/22] XIP: Add support for unwritten extents Ross Zwisler
2014-01-23 12:08 ` Matthew Wilcox
2014-01-23 19:13 ` Ross Zwisler
[not found] ` <CF0C370C.235F1%willy@linux.intel.com>
2014-01-27 23:32 ` Ross Zwisler
2014-01-28 3:49 ` Matthew Wilcox
2014-01-23 7:48 ` [PATCH v5 00/22] Rewrite XIP code and add XIP support to ext4 Dave Chinner
2014-01-23 7:53 ` Dave Chinner
2014-01-23 9:01 ` Dave Chinner
2014-01-23 12:12 ` Wilcox, Matthew R
2014-01-28 6:06 ` Dave Chinner
2014-01-30 6:42 ` Dave Chinner
2014-01-30 9:25 ` Dave Chinner
2014-01-31 3:06 ` Dave Chinner
2014-01-31 5:45 ` Ross Zwisler [this message]
2014-01-31 13:04 ` Dave Chinner
[not found] ` <CF1FF3EB.24114%matthew.r.wilcox@intel.com>
2014-02-11 23:12 ` [PATCH v5 19/22] ext4: Add XIP functionality Ross Zwisler
2014-02-13 0:00 ` Ross Zwisler
[not found] ` <CF215477.24281%matthew.r.wilcox@intel.com>
2014-02-12 23:53 ` [PATCH v5 06/22] Treat XIP like O_DIRECT Ross Zwisler
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