tree d58ee401205de8385c74a04e9b66101fc9a6e22b
parent c5f7ad233b8805dae06e694538d8095b19f3c560
author Artem Bityutskiy <Artem.Bityutskiy@nokia.com> 1280057354 +0300
committer Jens Axboe <jaxboe@fusionio.com> 1281200035 +0200

writeback: do not lose wake-ups in the forker thread - 2

Currently, if someone submits jobs for the default bdi, we can lose wake-up
events. E.g., this can happen if 'bdi_queue_work()' is called when
'bdi_forker_thread()' is executing code after 'wb_do_writeback(me, 0)', but
before 'set_current_state(TASK_INTERRUPTIBLE)'.

This situation is unlikely, and the result is not very severe - we'll just
delay the execution of the work, but this is still not very nice.

This patch fixes the issue by checking whether the default bdi has works before
the forker thread goes sleep.

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