From: Tao Ma <boyu.mt@taobao.com>
Date: Sat, 13 Aug 2011 16:30:59 +0000 (-0400)
Subject: ext4: Resolve the hang of direct i/o read in handling EXT4_IO_END_UNWRITTEN.
X-Git-Tag: v3.1-rc3~5^2~2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=32c80b32c053dc52712dedac5e4d0aa7c93fc353;p=pandora-kernel.git

ext4: Resolve the hang of direct i/o read in handling EXT4_IO_END_UNWRITTEN.

EXT4_IO_END_UNWRITTEN flag set and the increase of i_aiodio_unwritten
should be done simultaneously since ext4_end_io_nolock always clear
the flag and decrease the counter in the same time.

We don't increase i_aiodio_unwritten when setting
EXT4_IO_END_UNWRITTEN so it will go nagative and causes some process
to wait forever.

Part of the patch came from Eric in his e-mail, but it doesn't fix the
problem met by Michael actually.

http://marc.info/?l=linux-ext4&m=131316851417460&w=2

Reported-and-Tested-by: Michael Tokarev<mjt@tls.msk.ru>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
---

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