From: Christoph Hellwig <hch@lst.de>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-fsdevel@vger.kernel.org, linux-aio@kvack.org, hch@lst.de,
viro@zeniv.linux.org.uk
Subject: Re: [PATCH 02/22] block: add REQ_HIPRI_ASYNC
Date: Fri, 21 Dec 2018 12:20:36 +0100 [thread overview]
Message-ID: <20181221112036.GA7319@lst.de> (raw)
In-Reply-To: <20181218154230.3120-3-axboe@kernel.dk>
On Tue, Dec 18, 2018 at 08:42:10AM -0700, Jens Axboe wrote:
> For the upcoming async polled IO, we can't sleep allocating requests.
> If we do, then we introduce a deadlock where the submitter already
> has async polled IO in-flight, but can't wait for them to complete
> since polled requests must be active found and reaped.
So two comments here. First I think after the next -rc1 we really
need to rename REQ_HIPRI to REQ_POLLED. Unlike the iocb hipri flag
which is an advice to treat this I/O as urgent REQ_POLLED is a hard
charaterisation and having the hipri name is badly misnamed for that.
Second I retract my suggestion to add this _ASYNC variant, as it seems
to cause more confusion than it helps. I think instead we want
a helper like this:
static void bio_set_polled(struct bio *bio, struct kiocb *kiocb)
{
bio->bi_opf |= REQ_POLLED;
if (!is_sync_kiocb(kiocb)
bio->bi_opf |= REQ_NOWAIT;
}
maybe plus comments to better indicate the intentional and consolidate
the is_sync check.
next prev parent reply other threads:[~2018-12-21 11:20 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-18 15:42 [PATCHSET v9] Support for polled and buffered aio (and more) Jens Axboe
2018-12-18 15:42 ` [PATCH 01/22] fs: add an iopoll method to struct file_operations Jens Axboe
2018-12-18 15:42 ` [PATCH 02/22] block: add REQ_HIPRI_ASYNC Jens Axboe
2018-12-21 11:20 ` Christoph Hellwig [this message]
2018-12-21 14:33 ` Jens Axboe
2018-12-18 15:42 ` [PATCH 03/22] block: wire up block device iopoll method Jens Axboe
2018-12-18 15:42 ` [PATCH 04/22] block: use REQ_HIPRI_ASYNC for non-sync polled IO Jens Axboe
2018-12-18 15:42 ` [PATCH 05/22] iomap: wire up the iopoll method Jens Axboe
2018-12-18 15:42 ` [PATCH 06/22] aio: add io_setup2() system call Jens Axboe
2018-12-21 11:21 ` Christoph Hellwig
2018-12-18 15:42 ` [PATCH 07/22] aio: support for IO polling Jens Axboe
2018-12-21 11:25 ` Christoph Hellwig
2018-12-21 14:28 ` Jens Axboe
2018-12-18 15:42 ` [PATCH 08/22] aio: add submission side request cache Jens Axboe
2018-12-21 11:28 ` Christoph Hellwig
2018-12-21 15:37 ` Jens Axboe
2018-12-21 15:42 ` Jens Axboe
2018-12-18 15:42 ` [PATCH 09/22] fs: add fget_many() and fput_many() Jens Axboe
2018-12-18 15:42 ` [PATCH 10/22] aio: use fget/fput_many() for file references Jens Axboe
2018-12-18 15:42 ` [PATCH 11/22] aio: split iocb init from allocation Jens Axboe
2018-12-18 15:42 ` [PATCH 12/22] aio: batch aio_kiocb allocation Jens Axboe
2018-12-18 15:42 ` [PATCH 13/22] aio: split old ring complete out from aio_complete() Jens Axboe
2018-12-18 15:42 ` [PATCH 14/22] aio: pass in user index to __io_submit_one() Jens Axboe
2018-12-18 15:42 ` [PATCH 15/22] aio: add support for submission/completion rings Jens Axboe
2018-12-18 15:42 ` [PATCH 16/22] block: add BIO_HOLD_PAGES flag Jens Axboe
2018-12-21 11:30 ` Christoph Hellwig
2018-12-21 14:22 ` Jens Axboe
2018-12-18 15:42 ` [PATCH 17/22] block: implement bio helper to add iter bvec pages to bio Jens Axboe
2018-12-21 11:32 ` Christoph Hellwig
2018-12-21 14:21 ` Jens Axboe
2018-12-18 15:42 ` [PATCH 18/22] aio: add support for pre-mapped user IO buffers Jens Axboe
2018-12-18 15:42 ` [PATCH 19/22] aio: support kernel side submission for aio with SCQRING Jens Axboe
2018-12-18 15:42 ` [PATCH 20/22] aio: enable polling for IOCTX_FLAG_SQTHREAD Jens Axboe
2018-12-18 15:42 ` [PATCH 21/22] aio: utilize io_event->res2 for CQ ring Jens Axboe
2018-12-18 15:42 ` [PATCH 22/22] aio: add my copyright Jens Axboe
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