From: Theodore Ts'o <tytso@mit.edu>
To: Eryu Guan <guaneryu@gmail.com>
Cc: linux-ext4@vger.kernel.org
Subject: Re: [PATCH] ext4: don't read blocks from disk after extents being swapped in move_extent_per_page()
Date: Fri, 12 Feb 2016 01:21:58 -0500 [thread overview]
Message-ID: <20160212062158.GH11298@thunk.org> (raw)
In-Reply-To: <1455117406-15497-1-git-send-email-guaneryu@gmail.com>
On Wed, Feb 10, 2016 at 11:16:45PM +0800, Eryu Guan wrote:
> I notice ext4/307 fails occasionally on ppc64 host, reporting md5
> checksum mismatch after moving data from original file to donor file.
>
> The reason is that move_extent_per_page() calls __block_write_begin()
> and block_commit_write() to write saved data from original inode blocks
> to donor inode blocks, but __block_write_begin() not only maps buffer
> heads but also reads block content from disk if the size is not block
> size aligned. At this time the physical block number in mapped buffer
> head is pointing to the donor file not the original file, and that
> results in reading wrong data to page, which get written to disk in
> following block_commit_write call.
Thanks, applied.
- Ted
prev parent reply other threads:[~2016-02-12 6:22 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-10 15:16 [PATCH] ext4: don't read blocks from disk after extents being swapped in move_extent_per_page() Eryu Guan
2016-02-10 15:16 ` [PATCH] ext4: remove unused parameter "newblock" in convert_initialized_extent() Eryu Guan
2016-02-10 15:39 ` kbuild test robot
2016-02-10 16:09 ` [PATCH v2] " Eryu Guan
2016-02-12 6:23 ` Theodore Ts'o
2016-02-12 6:21 ` Theodore Ts'o [this message]
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