From: Ming Lei <ming.lei@redhat.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
Jeffle Xu <jefflexu@linux.alibaba.com>,
Mike Snitzer <snitzer@redhat.com>,
dm-devel@redhat.com
Subject: [RFC PATCH 10/11] block: add poll_capable method to support bio-based IO polling
Date: Tue, 16 Mar 2021 11:15:22 +0800 [thread overview]
Message-ID: <20210316031523.864506-11-ming.lei@redhat.com> (raw)
In-Reply-To: <20210316031523.864506-1-ming.lei@redhat.com>
From: Jeffle Xu <jefflexu@linux.alibaba.com>
This method can be used to check if bio-based device supports IO polling
or not. For mq devices, checking for hw queue in polling mode is
adequate, while the sanity check shall be implementation specific for
bio-based devices. For example, dm device needs to check if all
underlying devices are capable of IO polling.
Though bio-based device may have done the sanity check during the
device initialization phase, cacheing the result of this sanity check
(such as by cacheing in the queue_flags) may not work. Because for dm
devices, users could change the state of the underlying devices through
'/sys/block/<dev>/io_poll', bypassing the dm device above. In this case,
the cached result of the very beginning sanity check could be
out-of-date. Thus the sanity check needs to be done every time 'io_poll'
is to be modified.
Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
---
block/blk-sysfs.c | 14 +++++++++++---
include/linux/blkdev.h | 1 +
2 files changed, 12 insertions(+), 3 deletions(-)
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 0f4f0c8a7825..367c1d9a55c6 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -426,9 +426,17 @@ static ssize_t queue_poll_store(struct request_queue *q, const char *page,
unsigned long poll_on;
ssize_t ret;
- if (!q->tag_set || q->tag_set->nr_maps <= HCTX_TYPE_POLL ||
- !q->tag_set->map[HCTX_TYPE_POLL].nr_queues)
- return -EINVAL;
+ if (queue_is_mq(q)) {
+ if (!q->tag_set || q->tag_set->nr_maps <= HCTX_TYPE_POLL ||
+ !q->tag_set->map[HCTX_TYPE_POLL].nr_queues)
+ return -EINVAL;
+ } else {
+ struct gendisk *disk = queue_to_disk(q);
+
+ if (!disk->fops->poll_capable ||
+ !disk->fops->poll_capable(disk))
+ return -EINVAL;
+ }
ret = queue_var_store(&poll_on, page, count);
if (ret < 0)
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index bfab74b45f15..a46f975f2a2f 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1881,6 +1881,7 @@ struct block_device_operations {
int (*report_zones)(struct gendisk *, sector_t sector,
unsigned int nr_zones, report_zones_cb cb, void *data);
char *(*devnode)(struct gendisk *disk, umode_t *mode);
+ bool (*poll_capable)(struct gendisk *disk);
struct module *owner;
const struct pr_ops *pr_ops;
};
--
2.29.2
next prev parent reply other threads:[~2021-03-16 3:20 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-16 3:15 [RFC PATCH 00/11] block: support bio based io polling Ming Lei
2021-03-16 3:15 ` [RFC PATCH 01/11] block: add helper of blk_queue_poll Ming Lei
2021-03-16 3:26 ` Chaitanya Kulkarni
2021-03-16 3:15 ` [RFC PATCH 02/11] block: add one helper to free io_context Ming Lei
2021-03-16 3:15 ` [RFC PATCH 03/11] block: add helper of blk_create_io_context Ming Lei
2021-03-16 3:15 ` [RFC PATCH 04/11] block: create io poll context for submission and poll task Ming Lei
2021-03-16 3:15 ` [RFC PATCH 05/11] block: add req flag of REQ_TAG Ming Lei
2021-03-16 3:15 ` [RFC PATCH 06/11] block: add new field into 'struct bvec_iter' Ming Lei
2021-03-16 3:15 ` [RFC PATCH 07/11] block/mq: extract one helper function polling hw queue Ming Lei
2021-03-16 3:15 ` [RFC PATCH 08/11] block: use per-task poll context to implement bio based io poll Ming Lei
2021-03-16 6:46 ` JeffleXu
2021-03-16 7:17 ` Ming Lei
2021-03-16 8:52 ` JeffleXu
2021-03-17 2:54 ` Ming Lei
2021-03-17 3:53 ` JeffleXu
2021-03-17 6:54 ` Ming Lei
2021-03-16 11:00 ` JeffleXu
2021-03-17 3:38 ` Ming Lei
2021-03-17 3:49 ` JeffleXu
2021-03-17 7:19 ` Ming Lei
2021-03-18 14:51 ` Mike Snitzer
2021-03-16 3:15 ` [RFC PATCH 09/11] block: add queue_to_disk() to get gendisk from request_queue Ming Lei
2021-03-16 3:15 ` Ming Lei [this message]
2021-03-16 3:15 ` [RFC PATCH 11/11] dm: support IO polling for bio-based dm device Ming Lei
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