From: Jan Kara <jack@suse.cz>
Date: Wed, 9 Dec 2009 02:24:33 +0000 (-0500)
Subject: ext4: Avoid data / filesystem corruption when write fails to copy data
X-Git-Tag: v2.6.33-rc1~330^2~10
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b9a4207d5e911b938f73079a83cc2ae10524ec7f;p=pandora-kernel.git

ext4: Avoid data / filesystem corruption when write fails to copy data

When ext4_write_begin fails after allocating some blocks or
generic_perform_write fails to copy data to write, we truncate blocks
already instantiated beyond i_size.  Although these blocks were never
inside i_size, we have to truncate the pagecache of these blocks so
that corresponding buffers get unmapped.  Otherwise subsequent
__block_prepare_write (called because we are retrying the write) will
find the buffers mapped, not call ->get_block, and thus the page will
be backed by already freed blocks leading to filesystem and data
corruption.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
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