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Date: Sun, 26 Sep 2021 11:25:22 +0800
From: Ming Lei <ming.lei@...hat.com>
To: John Garry <john.garry@...wei.com>
Cc: axboe@...nel.dk, linux-block@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-scsi@...r.kernel.org,
hare@...e.de
Subject: Re: [PATCH v4 12/13] blk-mq: Use shared tags for shared sbitmap
support
On Fri, Sep 24, 2021 at 04:28:29PM +0800, John Garry wrote:
> Currently we use separate sbitmap pairs and active_queues atomic_t for
> shared sbitmap support.
>
> However a full sets of static requests are used per HW queue, which is
> quite wasteful, considering that the total number of requests usable at
> any given time across all HW queues is limited by the shared sbitmap depth.
>
> As such, it is considerably more memory efficient in the case of shared
> sbitmap to allocate a set of static rqs per tag set or request queue, and
> not per HW queue.
>
> So replace the sbitmap pairs and active_queues atomic_t with a shared
> tags per tagset and request queue, which will hold a set of shared static
> rqs.
>
> Since there is now no valid HW queue index to be passed to the blk_mq_ops
> .init and .exit_request callbacks, pass an invalid index token. This
> changes the semantics of the APIs, such that the callback would need to
> validate the HW queue index before using it. Currently no user of shared
> sbitmap actually uses the HW queue index (as would be expected).
>
> Continue to use term "shared sbitmap" for now, as the meaning is known.
>
> Signed-off-by: John Garry <john.garry@...wei.com>
> ---
> block/blk-mq-sched.c | 82 ++++++++++++++++++-------------------
> block/blk-mq-tag.c | 61 ++++++++++------------------
> block/blk-mq-tag.h | 6 +--
> block/blk-mq.c | 91 +++++++++++++++++++++++-------------------
> block/blk-mq.h | 5 ++-
> include/linux/blk-mq.h | 15 ++++---
> include/linux/blkdev.h | 3 +-
> 7 files changed, 125 insertions(+), 138 deletions(-)
>
> diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
> index d1b56bb9ac64..428da4949d80 100644
> --- a/block/blk-mq-sched.c
> +++ b/block/blk-mq-sched.c
> @@ -519,6 +519,11 @@ static int blk_mq_sched_alloc_map_and_rqs(struct request_queue *q,
> struct blk_mq_hw_ctx *hctx,
> unsigned int hctx_idx)
> {
> + if (blk_mq_is_sbitmap_shared(q->tag_set->flags)) {
> + hctx->sched_tags = q->shared_sbitmap_tags;
> + return 0;
> + }
> +
> hctx->sched_tags = blk_mq_alloc_map_and_rqs(q->tag_set, hctx_idx,
> q->nr_requests);
>
> @@ -527,61 +532,54 @@ static int blk_mq_sched_alloc_map_and_rqs(struct request_queue *q,
> return 0;
> }
>
> +static void blk_mq_exit_sched_shared_sbitmap(struct request_queue *queue)
> +{
> + blk_mq_free_rq_map(queue->shared_sbitmap_tags);
> + queue->shared_sbitmap_tags = NULL;
> +}
> +
> /* called in queue's release handler, tagset has gone away */
> -static void blk_mq_sched_tags_teardown(struct request_queue *q)
> +static void blk_mq_sched_tags_teardown(struct request_queue *q, unsigned int flags)
> {
> struct blk_mq_hw_ctx *hctx;
> int i;
>
> queue_for_each_hw_ctx(q, hctx, i) {
> if (hctx->sched_tags) {
> - blk_mq_free_rq_map(hctx->sched_tags, hctx->flags);
> + if (!blk_mq_is_sbitmap_shared(q->tag_set->flags))
> + blk_mq_free_rq_map(hctx->sched_tags);
> hctx->sched_tags = NULL;
> }
> }
> +
> + if (blk_mq_is_sbitmap_shared(flags))
> + blk_mq_exit_sched_shared_sbitmap(q);
> }
>
> static int blk_mq_init_sched_shared_sbitmap(struct request_queue *queue)
> {
> struct blk_mq_tag_set *set = queue->tag_set;
> - int alloc_policy = BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags);
> - struct blk_mq_hw_ctx *hctx;
> - int ret, i;
>
> /*
> * Set initial depth at max so that we don't need to reallocate for
> * updating nr_requests.
> */
> - ret = blk_mq_init_bitmaps(&queue->sched_bitmap_tags,
> - &queue->sched_breserved_tags,
> - MAX_SCHED_RQ, set->reserved_tags,
> - set->numa_node, alloc_policy);
> - if (ret)
> - return ret;
> -
> - queue_for_each_hw_ctx(queue, hctx, i) {
> - hctx->sched_tags->bitmap_tags =
> - &queue->sched_bitmap_tags;
> - hctx->sched_tags->breserved_tags =
> - &queue->sched_breserved_tags;
> - }
> + queue->shared_sbitmap_tags = blk_mq_alloc_map_and_rqs(set,
> + BLK_MQ_NO_HCTX_IDX,
> + MAX_SCHED_RQ);
> + if (!queue->shared_sbitmap_tags)
> + return -ENOMEM;
>
> blk_mq_tag_update_sched_shared_sbitmap(queue);
>
> return 0;
> }
>
> -static void blk_mq_exit_sched_shared_sbitmap(struct request_queue *queue)
> -{
> - sbitmap_queue_free(&queue->sched_bitmap_tags);
> - sbitmap_queue_free(&queue->sched_breserved_tags);
> -}
> -
> int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e)
> {
> + unsigned int i, flags = q->tag_set->flags;
> struct blk_mq_hw_ctx *hctx;
> struct elevator_queue *eq;
> - unsigned int i;
> int ret;
>
> if (!e) {
> @@ -598,21 +596,21 @@ int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e)
> q->nr_requests = 2 * min_t(unsigned int, q->tag_set->queue_depth,
> BLKDEV_DEFAULT_RQ);
>
> - queue_for_each_hw_ctx(q, hctx, i) {
> - ret = blk_mq_sched_alloc_map_and_rqs(q, hctx, i);
> + if (blk_mq_is_sbitmap_shared(flags)) {
> + ret = blk_mq_init_sched_shared_sbitmap(q);
> if (ret)
> - goto err_free_map_and_rqs;
> + return ret;
> }
>
> - if (blk_mq_is_sbitmap_shared(q->tag_set->flags)) {
> - ret = blk_mq_init_sched_shared_sbitmap(q);
> + queue_for_each_hw_ctx(q, hctx, i) {
> + ret = blk_mq_sched_alloc_map_and_rqs(q, hctx, i);
> if (ret)
> goto err_free_map_and_rqs;
> }
>
> ret = e->ops.init_sched(q, e);
> if (ret)
> - goto err_free_sbitmap;
> + goto err_free_map_and_rqs;
>
> blk_mq_debugfs_register_sched(q);
>
> @@ -632,12 +630,10 @@ int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e)
>
> return 0;
>
> -err_free_sbitmap:
> - if (blk_mq_is_sbitmap_shared(q->tag_set->flags))
> - blk_mq_exit_sched_shared_sbitmap(q);
> err_free_map_and_rqs:
> blk_mq_sched_free_rqs(q);
> - blk_mq_sched_tags_teardown(q);
> + blk_mq_sched_tags_teardown(q, flags);
> +
> q->elevator = NULL;
> return ret;
> }
> @@ -651,9 +647,15 @@ void blk_mq_sched_free_rqs(struct request_queue *q)
> struct blk_mq_hw_ctx *hctx;
> int i;
>
> - queue_for_each_hw_ctx(q, hctx, i) {
> - if (hctx->sched_tags)
> - blk_mq_free_rqs(q->tag_set, hctx->sched_tags, i);
> + if (blk_mq_is_sbitmap_shared(q->tag_set->flags)) {
> + blk_mq_free_rqs(q->tag_set, q->shared_sbitmap_tags,
> + BLK_MQ_NO_HCTX_IDX);
> + } else {
> + queue_for_each_hw_ctx(q, hctx, i) {
> + if (hctx->sched_tags)
> + blk_mq_free_rqs(q->tag_set,
> + hctx->sched_tags, i);
> + }
> }
> }
>
> @@ -674,8 +676,6 @@ void blk_mq_exit_sched(struct request_queue *q, struct elevator_queue *e)
> blk_mq_debugfs_unregister_sched(q);
> if (e->type->ops.exit_sched)
> e->type->ops.exit_sched(e);
> - blk_mq_sched_tags_teardown(q);
> - if (blk_mq_is_sbitmap_shared(flags))
> - blk_mq_exit_sched_shared_sbitmap(q);
> + blk_mq_sched_tags_teardown(q, flags);
> q->elevator = NULL;
> }
> diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
> index a0ecc6d88f84..4e71ce6b37ea 100644
> --- a/block/blk-mq-tag.c
> +++ b/block/blk-mq-tag.c
> @@ -27,10 +27,11 @@ bool __blk_mq_tag_busy(struct blk_mq_hw_ctx *hctx)
> if (blk_mq_is_sbitmap_shared(hctx->flags)) {
> struct request_queue *q = hctx->queue;
> struct blk_mq_tag_set *set = q->tag_set;
> + struct blk_mq_tags *tags = set->shared_sbitmap_tags;
The local variable of 'set' can be removed and just retrieve 'tags' from
hctx->tags.
>
> if (!test_bit(QUEUE_FLAG_HCTX_ACTIVE, &q->queue_flags) &&
> !test_and_set_bit(QUEUE_FLAG_HCTX_ACTIVE, &q->queue_flags))
> - atomic_inc(&set->active_queues_shared_sbitmap);
> + atomic_inc(&tags->active_queues);
> } else {
> if (!test_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state) &&
> !test_and_set_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state))
> @@ -61,10 +62,12 @@ void __blk_mq_tag_idle(struct blk_mq_hw_ctx *hctx)
> struct blk_mq_tag_set *set = q->tag_set;
>
> if (blk_mq_is_sbitmap_shared(hctx->flags)) {
> + struct blk_mq_tags *tags = set->shared_sbitmap_tags;
> +
Same with above.
> if (!test_and_clear_bit(QUEUE_FLAG_HCTX_ACTIVE,
> &q->queue_flags))
> return;
> - atomic_dec(&set->active_queues_shared_sbitmap);
> + atomic_dec(&tags->active_queues);
> } else {
> if (!test_and_clear_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state))
> return;
> @@ -510,38 +513,10 @@ static int blk_mq_init_bitmap_tags(struct blk_mq_tags *tags,
> return 0;
> }
>
> -int blk_mq_init_shared_sbitmap(struct blk_mq_tag_set *set)
> -{
> - int alloc_policy = BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags);
> - int i, ret;
> -
> - ret = blk_mq_init_bitmaps(&set->__bitmap_tags, &set->__breserved_tags,
> - set->queue_depth, set->reserved_tags,
> - set->numa_node, alloc_policy);
> - if (ret)
> - return ret;
> -
> - for (i = 0; i < set->nr_hw_queues; i++) {
> - struct blk_mq_tags *tags = set->tags[i];
> -
> - tags->bitmap_tags = &set->__bitmap_tags;
> - tags->breserved_tags = &set->__breserved_tags;
> - }
> -
> - return 0;
> -}
> -
> -void blk_mq_exit_shared_sbitmap(struct blk_mq_tag_set *set)
> -{
> - sbitmap_queue_free(&set->__bitmap_tags);
> - sbitmap_queue_free(&set->__breserved_tags);
> -}
> -
> struct blk_mq_tags *blk_mq_init_tags(unsigned int total_tags,
> unsigned int reserved_tags,
> - int node, unsigned int flags)
> + int node, int alloc_policy)
> {
> - int alloc_policy = BLK_MQ_FLAG_TO_ALLOC_POLICY(flags);
> struct blk_mq_tags *tags;
>
> if (total_tags > BLK_MQ_TAG_MAX) {
> @@ -557,9 +532,6 @@ struct blk_mq_tags *blk_mq_init_tags(unsigned int total_tags,
> tags->nr_reserved_tags = reserved_tags;
> spin_lock_init(&tags->lock);
>
> - if (blk_mq_is_sbitmap_shared(flags))
> - return tags;
> -
> if (blk_mq_init_bitmap_tags(tags, node, alloc_policy) < 0) {
> kfree(tags);
> return NULL;
> @@ -567,12 +539,10 @@ struct blk_mq_tags *blk_mq_init_tags(unsigned int total_tags,
> return tags;
> }
>
> -void blk_mq_free_tags(struct blk_mq_tags *tags, unsigned int flags)
> +void blk_mq_free_tags(struct blk_mq_tags *tags)
> {
> - if (!blk_mq_is_sbitmap_shared(flags)) {
> - sbitmap_queue_free(tags->bitmap_tags);
> - sbitmap_queue_free(tags->breserved_tags);
> - }
> + sbitmap_queue_free(tags->bitmap_tags);
> + sbitmap_queue_free(tags->breserved_tags);
> kfree(tags);
> }
>
> @@ -603,6 +573,13 @@ int blk_mq_tag_update_depth(struct blk_mq_hw_ctx *hctx,
> if (tdepth > MAX_SCHED_RQ)
> return -EINVAL;
>
> + /*
> + * Only the sbitmap needs resizing since we allocated the max
> + * initially.
> + */
> + if (blk_mq_is_sbitmap_shared(set->flags))
> + return 0;
> +
> new = blk_mq_alloc_map_and_rqs(set, hctx->queue_num, tdepth);
> if (!new)
> return -ENOMEM;
> @@ -623,12 +600,14 @@ int blk_mq_tag_update_depth(struct blk_mq_hw_ctx *hctx,
>
> void blk_mq_tag_resize_shared_sbitmap(struct blk_mq_tag_set *set, unsigned int size)
> {
> - sbitmap_queue_resize(&set->__bitmap_tags, size - set->reserved_tags);
> + struct blk_mq_tags *tags = set->shared_sbitmap_tags;
> +
> + sbitmap_queue_resize(&tags->__bitmap_tags, size - set->reserved_tags);
> }
>
> void blk_mq_tag_update_sched_shared_sbitmap(struct request_queue *q)
> {
> - sbitmap_queue_resize(&q->sched_bitmap_tags,
> + sbitmap_queue_resize(q->shared_sbitmap_tags->bitmap_tags,
> q->nr_requests - q->tag_set->reserved_tags);
> }
>
> diff --git a/block/blk-mq-tag.h b/block/blk-mq-tag.h
> index 88f3c6485543..e433e39a9cfa 100644
> --- a/block/blk-mq-tag.h
> +++ b/block/blk-mq-tag.h
> @@ -30,16 +30,14 @@ struct blk_mq_tags {
>
> extern struct blk_mq_tags *blk_mq_init_tags(unsigned int nr_tags,
> unsigned int reserved_tags,
> - int node, unsigned int flags);
> -extern void blk_mq_free_tags(struct blk_mq_tags *tags, unsigned int flags);
> + int node, int alloc_policy);
> +extern void blk_mq_free_tags(struct blk_mq_tags *tags);
> extern int blk_mq_init_bitmaps(struct sbitmap_queue *bitmap_tags,
> struct sbitmap_queue *breserved_tags,
> unsigned int queue_depth,
> unsigned int reserved,
> int node, int alloc_policy);
>
> -extern int blk_mq_init_shared_sbitmap(struct blk_mq_tag_set *set);
> -extern void blk_mq_exit_shared_sbitmap(struct blk_mq_tag_set *set);
> extern unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data);
> extern void blk_mq_put_tag(struct blk_mq_tags *tags, struct blk_mq_ctx *ctx,
> unsigned int tag);
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index 464ea20b9bcb..ece43855bcdf 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -2344,7 +2344,10 @@ void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
> struct blk_mq_tags *drv_tags;
> struct page *page;
>
> - drv_tags = set->tags[hctx_idx];
> + if (blk_mq_is_sbitmap_shared(set->flags))
> + drv_tags = set->shared_sbitmap_tags;
> + else
> + drv_tags = set->tags[hctx_idx];
>
> if (tags->static_rqs && set->ops->exit_request) {
> int i;
> @@ -2373,21 +2376,20 @@ void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
> }
> }
>
> -void blk_mq_free_rq_map(struct blk_mq_tags *tags, unsigned int flags)
> +void blk_mq_free_rq_map(struct blk_mq_tags *tags)
> {
> kfree(tags->rqs);
> tags->rqs = NULL;
> kfree(tags->static_rqs);
> tags->static_rqs = NULL;
>
> - blk_mq_free_tags(tags, flags);
> + blk_mq_free_tags(tags);
> }
>
> static struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set,
> unsigned int hctx_idx,
> unsigned int nr_tags,
> - unsigned int reserved_tags,
> - unsigned int flags)
> + unsigned int reserved_tags)
> {
> struct blk_mq_tags *tags;
> int node;
> @@ -2396,7 +2398,8 @@ static struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set,
> if (node == NUMA_NO_NODE)
> node = set->numa_node;
>
> - tags = blk_mq_init_tags(nr_tags, reserved_tags, node, flags);
> + tags = blk_mq_init_tags(nr_tags, reserved_tags, node,
> + BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags));
> if (!tags)
> return NULL;
>
> @@ -2404,7 +2407,7 @@ static struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set,
> GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
> node);
> if (!tags->rqs) {
> - blk_mq_free_tags(tags, flags);
> + blk_mq_free_tags(tags);
> return NULL;
> }
>
> @@ -2413,7 +2416,7 @@ static struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set,
> node);
> if (!tags->static_rqs) {
> kfree(tags->rqs);
> - blk_mq_free_tags(tags, flags);
> + blk_mq_free_tags(tags);
> return NULL;
> }
>
> @@ -2855,14 +2858,13 @@ struct blk_mq_tags *blk_mq_alloc_map_and_rqs(struct blk_mq_tag_set *set,
> struct blk_mq_tags *tags;
> int ret;
>
> - tags = blk_mq_alloc_rq_map(set, hctx_idx, depth, set->reserved_tags,
> - set->flags);
> + tags = blk_mq_alloc_rq_map(set, hctx_idx, depth, set->reserved_tags);
> if (!tags)
> return NULL;
>
> ret = blk_mq_alloc_rqs(set, tags, hctx_idx, depth);
> if (ret) {
> - blk_mq_free_rq_map(tags, set->flags);
> + blk_mq_free_rq_map(tags);
> return NULL;
> }
>
> @@ -2872,6 +2874,12 @@ struct blk_mq_tags *blk_mq_alloc_map_and_rqs(struct blk_mq_tag_set *set,
> static bool __blk_mq_alloc_map_and_rqs(struct blk_mq_tag_set *set,
> int hctx_idx)
> {
> + if (blk_mq_is_sbitmap_shared(set->flags)) {
> + set->tags[hctx_idx] = set->shared_sbitmap_tags;
> +
> + return true;
> + }
> +
> set->tags[hctx_idx] = blk_mq_alloc_map_and_rqs(set, hctx_idx,
> set->queue_depth);
>
> @@ -2882,14 +2890,22 @@ void blk_mq_free_map_and_rqs(struct blk_mq_tag_set *set,
> struct blk_mq_tags *tags,
> unsigned int hctx_idx)
> {
> - unsigned int flags = set->flags;
> -
> if (tags) {
> blk_mq_free_rqs(set, tags, hctx_idx);
> - blk_mq_free_rq_map(tags, flags);
> + blk_mq_free_rq_map(tags);
> }
> }
>
> +static void __blk_mq_free_map_and_rqs(struct blk_mq_tag_set *set,
> + struct blk_mq_tags *tags,
> + unsigned int hctx_idx)
> +{
> + if (blk_mq_is_sbitmap_shared(set->flags))
> + return;
> +
> + blk_mq_free_map_and_rqs(set, tags, hctx_idx);
> +}
> +
> static void blk_mq_map_swqueue(struct request_queue *q)
> {
> unsigned int i, j, hctx_idx;
> @@ -2968,7 +2984,7 @@ static void blk_mq_map_swqueue(struct request_queue *q)
> * allocation
> */
> if (i && set->tags[i]) {
> - blk_mq_free_map_and_rqs(set, set->tags[i], i);
> + __blk_mq_free_map_and_rqs(set, set->tags[i], i);
> set->tags[i] = NULL;
> }
>
> @@ -3266,7 +3282,7 @@ static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
> struct blk_mq_hw_ctx *hctx = hctxs[j];
>
> if (hctx) {
> - blk_mq_free_map_and_rqs(set, set->tags[j], j);
> + __blk_mq_free_map_and_rqs(set, set->tags[j], j);
> set->tags[j] = NULL;
> blk_mq_exit_hctx(q, set, hctx, j);
> hctxs[j] = NULL;
> @@ -3354,6 +3370,14 @@ static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
> {
> int i;
>
> + if (blk_mq_is_sbitmap_shared(set->flags)) {
> + set->shared_sbitmap_tags = blk_mq_alloc_map_and_rqs(set,
> + BLK_MQ_NO_HCTX_IDX,
> + set->queue_depth);
> + if (!set->shared_sbitmap_tags)
> + return -ENOMEM;
> + }
> +
> for (i = 0; i < set->nr_hw_queues; i++) {
> if (!__blk_mq_alloc_map_and_rqs(set, i))
> goto out_unwind;
> @@ -3364,10 +3388,15 @@ static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
>
> out_unwind:
> while (--i >= 0) {
> - blk_mq_free_map_and_rqs(set, set->tags[i], i);
> + __blk_mq_free_map_and_rqs(set, set->tags[i], i);
> set->tags[i] = NULL;
> }
>
> + if (blk_mq_is_sbitmap_shared(set->flags)) {
> + blk_mq_free_map_and_rqs(set, set->shared_sbitmap_tags,
> + BLK_MQ_NO_HCTX_IDX);
> + }
> +
> return -ENOMEM;
> }
>
> @@ -3546,25 +3575,11 @@ int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
> if (ret)
> goto out_free_mq_map;
>
> - if (blk_mq_is_sbitmap_shared(set->flags)) {
> - atomic_set(&set->active_queues_shared_sbitmap, 0);
> -
> - if (blk_mq_init_shared_sbitmap(set)) {
> - ret = -ENOMEM;
> - goto out_free_mq_rq_maps;
> - }
> - }
> -
> mutex_init(&set->tag_list_lock);
> INIT_LIST_HEAD(&set->tag_list);
>
> return 0;
>
> -out_free_mq_rq_maps:
> - for (i = 0; i < set->nr_hw_queues; i++) {
> - blk_mq_free_map_and_rqs(set, set->tags[i], i);
> - set->tags[i] = NULL;
> - }
> out_free_mq_map:
> for (i = 0; i < set->nr_maps; i++) {
> kfree(set->map[i].mq_map);
> @@ -3597,12 +3612,14 @@ void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
> int i, j;
>
> for (i = 0; i < set->nr_hw_queues; i++) {
> - blk_mq_free_map_and_rqs(set, set->tags[i], i);
> + __blk_mq_free_map_and_rqs(set, set->tags[i], i);
> set->tags[i] = NULL;
> }
>
> - if (blk_mq_is_sbitmap_shared(set->flags))
> - blk_mq_exit_shared_sbitmap(set);
> + if (blk_mq_is_sbitmap_shared(set->flags)) {
> + blk_mq_free_map_and_rqs(set, set->shared_sbitmap_tags,
> + BLK_MQ_NO_HCTX_IDX);
> + }
>
> for (j = 0; j < set->nr_maps; j++) {
> kfree(set->map[j].mq_map);
> @@ -3640,12 +3657,6 @@ int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
> if (hctx->sched_tags) {
> ret = blk_mq_tag_update_depth(hctx, &hctx->sched_tags,
> nr, true);
> - if (blk_mq_is_sbitmap_shared(set->flags)) {
> - hctx->sched_tags->bitmap_tags =
> - &q->sched_bitmap_tags;
> - hctx->sched_tags->breserved_tags =
> - &q->sched_breserved_tags;
> - }
> } else {
> ret = blk_mq_tag_update_depth(hctx, &hctx->tags, nr,
> false);
> diff --git a/block/blk-mq.h b/block/blk-mq.h
> index bcb0ca89d37a..b34385211e0a 100644
> --- a/block/blk-mq.h
> +++ b/block/blk-mq.h
> @@ -54,7 +54,7 @@ void blk_mq_put_rq_ref(struct request *rq);
> */
> void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
> unsigned int hctx_idx);
> -void blk_mq_free_rq_map(struct blk_mq_tags *tags, unsigned int flags);
> +void blk_mq_free_rq_map(struct blk_mq_tags *tags);
> struct blk_mq_tags *blk_mq_alloc_map_and_rqs(struct blk_mq_tag_set *set,
> unsigned int hctx_idx, unsigned int depth);
> void blk_mq_free_map_and_rqs(struct blk_mq_tag_set *set,
> @@ -331,10 +331,11 @@ static inline bool hctx_may_queue(struct blk_mq_hw_ctx *hctx,
> if (blk_mq_is_sbitmap_shared(hctx->flags)) {
> struct request_queue *q = hctx->queue;
> struct blk_mq_tag_set *set = q->tag_set;
> + struct blk_mq_tags *tags = set->shared_sbitmap_tags;
Same with above, tags can be retrieved from hctx->tags directly,
and both 'q' and 'set' can be killed.
>
> if (!test_bit(QUEUE_FLAG_HCTX_ACTIVE, &q->queue_flags))
> return true;
> - users = atomic_read(&set->active_queues_shared_sbitmap);
> + users = atomic_read(&tags->active_queues);
> } else {
> if (!test_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state))
> return true;
> diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
> index 13ba1861e688..808854a8ebc4 100644
> --- a/include/linux/blk-mq.h
> +++ b/include/linux/blk-mq.h
> @@ -232,13 +232,11 @@ enum hctx_type {
> * @flags: Zero or more BLK_MQ_F_* flags.
> * @driver_data: Pointer to data owned by the block driver that created this
> * tag set.
> - * @active_queues_shared_sbitmap:
> - * number of active request queues per tag set.
> - * @__bitmap_tags: A shared tags sbitmap, used over all hctx's
> - * @__breserved_tags:
> - * A shared reserved tags sbitmap, used over all hctx's
> * @tags: Tag sets. One tag set per hardware queue. Has @nr_hw_queues
> * elements.
> + * @shared_sbitmap_tags:
> + * Shared sbitmap set of tags. Has @nr_hw_queues elements. If
> + * set, shared by all @tags.
> * @tag_list_lock: Serializes tag_list accesses.
> * @tag_list: List of the request queues that use this tag set. See also
> * request_queue.tag_set_list.
> @@ -255,12 +253,11 @@ struct blk_mq_tag_set {
> unsigned int timeout;
> unsigned int flags;
> void *driver_data;
> - atomic_t active_queues_shared_sbitmap;
>
> - struct sbitmap_queue __bitmap_tags;
> - struct sbitmap_queue __breserved_tags;
> struct blk_mq_tags **tags;
>
> + struct blk_mq_tags *shared_sbitmap_tags;
> +
> struct mutex tag_list_lock;
> struct list_head tag_list;
> };
> @@ -432,6 +429,8 @@ enum {
> ((policy & ((1 << BLK_MQ_F_ALLOC_POLICY_BITS) - 1)) \
> << BLK_MQ_F_ALLOC_POLICY_START_BIT)
>
> +#define BLK_MQ_NO_HCTX_IDX (-1U)
> +
> struct gendisk *__blk_mq_alloc_disk(struct blk_mq_tag_set *set, void *queuedata,
> struct lock_class_key *lkclass);
> #define blk_mq_alloc_disk(set, queuedata) \
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index 4baf9435232d..17e50e5ef47b 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -459,8 +459,7 @@ struct request_queue {
>
> atomic_t nr_active_requests_shared_sbitmap;
>
> - struct sbitmap_queue sched_bitmap_tags;
> - struct sbitmap_queue sched_breserved_tags;
> + struct blk_mq_tags *shared_sbitmap_tags;
Maybe better with shared_sched_sbitmap_tags or sched_sbitmap_tags?
Nice cleanup, once the above comments are addressed, feel free to
add:
Reviewed-by: Ming Lei <ming.lei@...hat.com>
Thanks,
Ming
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