From: Ming Lei <tom.leiming@gmail.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: Goldwyn Rodrigues <rgoldwyn@suse.de>,
Linux FS Devel <linux-fsdevel@vger.kernel.org>,
Jan Kara <jack@suse.com>, Christoph Hellwig <hch@infradead.org>,
linux-block <linux-block@vger.kernel.org>,
Btrfs BTRFS <linux-btrfs@vger.kernel.org>,
"open list:EXT4 FILE SYSTEM" <linux-ext4@vger.kernel.org>,
"open list:XFS FILESYSTEM" <linux-xfs@vger.kernel.org>,
Sagi Grimberg <sagi@grimberg.me>,
avi@scylladb.com, linux-api@vger.kernel.org,
Matthew Wilcox <willy@infradead.org>,
Goldwyn Rodrigues <rgoldwyn@suse.com>
Subject: Re: [PATCH 5/8] nowait aio: return on congested block device
Date: Fri, 17 Mar 2017 10:03:18 +0800 [thread overview]
Message-ID: <CACVXFVMTxxRM==3ton-=LmDHYKpBu2Sh59hs_gyvFCUtnQwjVQ@mail.gmail.com> (raw)
In-Reply-To: <eee4683d-9f44-434f-b97f-b0b24c7b3dab@kernel.dk>
On Thu, Mar 16, 2017 at 10:33 PM, Jens Axboe <axboe@kernel.dk> wrote:
> On 03/15/2017 03:51 PM, Goldwyn Rodrigues wrote:
>> diff --git a/block/blk-core.c b/block/blk-core.c
>> index 0eeb99e..2e5cba2 100644
>> --- a/block/blk-core.c
>> +++ b/block/blk-core.c
>> @@ -2014,7 +2019,7 @@ blk_qc_t generic_make_request(struct bio *bio)
>> do {
>> struct request_queue *q = bdev_get_queue(bio->bi_bdev);
>>
>> - if (likely(blk_queue_enter(q, false) == 0)) {
>> + if (likely(blk_queue_enter(q, bio_flagged(bio, BIO_NOWAIT)) == 0)) {
>> struct bio_list hold;
>> struct bio_list lower, same;
>>
>> @@ -2040,7 +2045,10 @@ blk_qc_t generic_make_request(struct bio *bio)
>> bio_list_merge(&bio_list_on_stack, &same);
>> bio_list_merge(&bio_list_on_stack, &hold);
>> } else {
>> - bio_io_error(bio);
>> + if (unlikely(bio_flagged(bio, BIO_NOWAIT)))
>> + bio_wouldblock_error(bio);
>> + else
>> + bio_io_error(bio);
>
> This doesn't look right. What if the queue is dying, and BIO_NOWAIT just
> happened to be set?
>
> And you're missing wbt_wait() as well as a blocking point. Ditto in
> blk-mq.
There are also tons of block points in dm/md/bcache, which need to be
considered or be documented at least, :-)
Thanks,
Ming Lei
next prev parent reply other threads:[~2017-03-17 2:03 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-15 21:50 [PATCH 0/8 v3] No wait AIO Goldwyn Rodrigues
2017-03-15 21:51 ` [PATCH 1/8] nowait aio: Introduce IOCB_RW_FLAG_NOWAIT Goldwyn Rodrigues
2017-03-15 21:51 ` [PATCH 2/8] nowait aio: Return if cannot get hold of i_rwsem Goldwyn Rodrigues
2017-03-15 21:51 ` [PATCH 3/8] nowait aio: return if direct write will trigger writeback Goldwyn Rodrigues
2017-03-16 13:08 ` Matthew Wilcox
2017-03-16 13:46 ` Goldwyn Rodrigues
2017-03-16 13:20 ` Matthew Wilcox
[not found] ` <20170316132052.GG4033-PfSpb0PWhxZc2C7mugBRk2EX/6BAtgUQ@public.gmane.org>
2017-03-16 13:46 ` Goldwyn Rodrigues
2017-03-15 21:51 ` [PATCH 4/8] nowait-aio: Introduce IOMAP_NOWAIT Goldwyn Rodrigues
2017-03-15 21:51 ` [PATCH 5/8] nowait aio: return on congested block device Goldwyn Rodrigues
[not found] ` <20170315215107.5628-6-rgoldwyn-l3A5Bk7waGM@public.gmane.org>
2017-03-16 14:33 ` Jens Axboe
2017-03-17 2:03 ` Ming Lei [this message]
2017-03-17 12:23 ` Goldwyn Rodrigues
[not found] ` <eee4683d-9f44-434f-b97f-b0b24c7b3dab-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org>
2017-03-24 11:32 ` Goldwyn Rodrigues
2017-03-24 14:39 ` Jens Axboe
2017-03-16 21:31 ` Dave Chinner
2017-03-17 12:23 ` Goldwyn Rodrigues
2017-03-20 17:33 ` Jan Kara
2017-03-15 21:51 ` [PATCH 6/8] nowait aio: ext4 Goldwyn Rodrigues
2017-03-15 21:51 ` [PATCH 7/8] nowait aio: xfs Goldwyn Rodrigues
2017-03-15 21:51 ` [PATCH 8/8] nowait aio: btrfs Goldwyn Rodrigues
2017-04-03 18:52 [PATCH 0/8 v4] No wait AIO Goldwyn Rodrigues
2017-04-03 18:53 ` [PATCH 5/8] nowait aio: return on congested block device Goldwyn Rodrigues
2017-04-04 6:49 ` Christoph Hellwig
2017-04-14 12:02 [PATCH 0/8 v6] No wait AIO Goldwyn Rodrigues
2017-04-14 12:02 ` [PATCH 5/8] nowait aio: return on congested block device Goldwyn Rodrigues
2017-04-19 6:45 ` Christoph Hellwig
2017-04-19 15:21 ` Goldwyn Rodrigues
2017-04-20 13:43 ` Jan Kara
2017-04-24 21:10 ` Goldwyn Rodrigues
2017-04-25 2:28 ` Jens Axboe
2017-05-09 12:22 [PATCH 0/8 v7] No wait AIO Goldwyn Rodrigues
2017-05-09 12:22 ` [PATCH 5/8] nowait aio: return on congested block device Goldwyn Rodrigues
2017-05-11 7:44 ` Christoph Hellwig
[not found] ` <20170511074451.GD15626-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2017-05-11 18:16 ` Goldwyn Rodrigues
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