On 09/02/2014 08:33 AM, Liu Bo wrote: > On Mon, Sep 01, 2014 at 02:56:15PM +0800, Miao Xie wrote: >> On Fri, 29 Aug 2014 14:31:48 -0400, Chris Mason wrote: >>> On 07/29/2014 05:24 AM, Miao Xie wrote: >>>> This patch implement data repair function when direct read fails. >>>> >>>> The detail of the implementation is: >>>> - When we find the data is not right, we try to read the data from the >>>> other >>>> mirror. >>>> - After we get right data, we write it back to the corrupted mirror. >>>> - And if the data on the new mirror is still corrupted, we will try next >>>> mirror until we read right data or all the mirrors are traversed. >>>> - After the above work, we set the uptodate flag according to the result. >>>> >>>> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c >>>> index 08e65e9..56b1546 100644 >>>> --- a/fs/btrfs/disk-io.c >>>> +++ b/fs/btrfs/disk-io.c >>>> @@ -698,7 +719,12 @@ static void end_workqueue_bio(struct bio *bio, int >>>> err) >>>> >>>> fs_info = end_io_wq->info; >>>> end_io_wq->error = err; >>>> - btrfs_init_work(&end_io_wq->work, end_workqueue_fn, NULL, NULL); >>>> + >>>> + if (likely(end_io_wq->metadata != BTRFS_WQ_ENDIO_DIO_REPAIR)) >>>> + btrfs_init_work(&end_io_wq->work, end_workqueue_fn, NULL, >>>> + NULL); >>>> + else >>>> + INIT_WORK(&end_io_wq->work.normal_work, dio_end_workqueue_fn); >>> >>> It's not clear why this one is using INIT_WORK instead of >>> btrfs_init_work, or why we're calling directly into queue_work instead >>> of btrfs_queue_work. What am I missing? >> >> I'm sorry that I forgot writing the explanation in this patch's changlog, >> I wrote it in Patch 0. >> >> "2.When the io on the mirror ends, we will insert the endio work into the >> system workqueue, not btrfs own endio workqueue, because the original >> endio work is still blocked in the btrfs endio workqueue, if we insert >> the endio work of the io on the mirror into that workqueue, deadlock >> would happen." > > Can you elaborate the deadlock? > > Now that buffer read can insert a subsequent read-mirror bio into btrfs endio > workqueue without problems, what's the difference?
We do have problems if we're inserting dependent items in the same workqueue. Miao, please make a repair workqueue. I'll also have a use for it in the raid56 parity work I think. -chris -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
