From: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Date: Sun, 25 Jul 2010 11:29:15 +0000 (+0300)
Subject: writeback: do not lose wake-ups in bdi threads
X-Git-Tag: v2.6.36-rc1~288^2~19
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=297252c81de8043ca6c36e5984c24fdb5aab9013;p=pandora-kernel.git

writeback: do not lose wake-ups in bdi threads

Currently, bdi threads ('bdi_writeback_thread()') can lose wake-ups. For
example, if 'bdi_queue_work()' is executed after the bdi thread have had
finished 'wb_do_writeback()' but before it called
'schedule_timeout_interruptible()'.

To fix this issue, we have to check whether we have works to process after we
have changed the task state to 'TASK_INTERRUPTIBLE'.

This patch also clean-ups handling of the cases when 'dirty_writeback_interval'
is zero or non-zero.

Additionally, this patch also removes unneeded 'list_empty_careful()' call.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
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