On 08/05/2010 08:53 PM, Jan Kara wrote: > Commit 83ba7b071f30f7c01f72518ad72d5cd203c27502 broke writeback_in_progress() > as in that commit we started to remove work items from the list at the > moment we start working on them and not at the moment they are finished. > Thus if the flusher thread was doing some work but there was no other > work queued, writeback_in_progress() returned false. This could in > particular cause unnecessary queueing of background writeback from > balance_dirty_pages() or writeout work from writeback_sb_if_idle(). > > This patch fixes the problem by introducing a bit in the bdi state which > indicates that the flusher thread is processing some work and uses this > bit for writeback_in_progress() test. > > NOTE: Both callsites of writeback_in_progress() (namely, > writeback_inodes_sb_if_idle() and balance_dirty_pages()) would actually > need a different information than what writeback_in_progress() provides. > They would need to know whether *the kind of writeback they are going > to submit* is already queued. But this information isn't that simple > to provide so let's fix writeback_in_progress() for the time being. I left this deliberatly vague, as there's no good way to answer the question that the caller wants to know about. Alternatively, augment the list_empty() check with a task running check. I guess that would require the wb lock, so your bit set/check is the best solution I think. Acked-by: Jens Axboe <jaxboe@xxxxxxxxxxxx> -- Jens Axboe Confidentiality Notice: This e-mail message, its contents and any attachments to it are confidential to the intended recipient, and may contain information that is privileged and/or exempt from disclosure under applicable law. If you are not the intended recipient, please immediately notify the sender and destroy the original e-mail message and any attachments (and any copies that may have been made) from your system or otherwise. Any unauthorized use, copying, disclosure or distribution of this information is strictly prohibited. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
