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From: Goldwyn Rodrigues <rgoldwyn@suse.de>
To: linux-block@vger.kernel.org
Cc: axboe@kernel.dk, shli@kernel.org
Subject: [PATCH v2 0/9] Nowait support for stacked block devices
Date: Wed,  4 Oct 2017 08:55:02 -0500	[thread overview]
Message-ID: <20171004135511.26110-1-rgoldwyn@suse.de> (raw)

This is a continuation of the nowait support which was incorporated
a while back. We introduced REQ_NOWAIT which would return immediately
if the call would block at the block layer. Request based-devices
do not wait. However, bio based devices (the ones which exclusively
call make_request_fn) need to be trained to handle REQ_NOWAIT.

This effort covers the devices under MD and DM which would block
for any reason. If there should be more devices or situations
which need to be covered, please let me know.

The problem with partial writes discussed during v1 turned out
to be a bug in partial writes during direct I/O and is fixed
by the submitted patch[1].

Changes since v1:
 - mddev to return early in case the device is suspended, within the md code as opposed to ->make_request()
 - Check for nowait support with all the lower devices. Same with if adding a device which does not support nowait.
 - Nowait under each raid is checked before the final I/O submission for the entire I/O.

[1] https://patchwork.kernel.org/patch/9979887/

-- 
Goldwyn

             reply	other threads:[~2017-10-04 13:55 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-04 13:55 Goldwyn Rodrigues [this message]
2017-10-04 13:55 ` [PATCH 1/9] QUEUE_FLAG_NOWAIT to indicate device supports nowait Goldwyn Rodrigues
2017-10-04 13:55 ` [PATCH 2/9] md: Add nowait support to md Goldwyn Rodrigues
2017-10-04 13:55 ` [PATCH 3/9] md: raid1 nowait support Goldwyn Rodrigues
2017-10-04 13:55 ` [PATCH 4/9] md: raid10 " Goldwyn Rodrigues
2017-10-04 13:55 ` [PATCH 5/9] md: raid5 " Goldwyn Rodrigues
2017-10-04 13:55 ` [PATCH 6/9] dm: add " Goldwyn Rodrigues
2017-10-04 13:55 ` [PATCH 7/9] dm: Add nowait support to raid1 Goldwyn Rodrigues
2017-10-04 13:55 ` [PATCH 8/9] dm: Add nowait support to dm-delay Goldwyn Rodrigues
2017-10-04 13:55 ` [PATCH 9/9] dm-mpath: Add nowait support Goldwyn Rodrigues
2017-10-05 17:19 ` [PATCH v2 0/9] Nowait support for stacked block devices Shaohua Li
2017-10-06 12:01   ` Goldwyn Rodrigues
2017-10-10 22:36     ` Shaohua Li

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