| Message ID | 1591810159-240929-5-git-send-email-john.garry@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | blk-mq/scsi: Provide hostwide shared tags for SCSI HBAs | expand |
On Thu, Jun 11, 2020 at 01:29:11AM +0800, John Garry wrote: > Some SCSI HBAs (such as HPSA, megaraid, mpt3sas, hisi_sas_v3 ..) support > multiple reply queues with single hostwide tags. > > In addition, these drivers want to use interrupt assignment in > pci_alloc_irq_vectors(PCI_IRQ_AFFINITY). However, as discussed in [0], > CPU hotplug may cause in-flight IO completion to not be serviced when an > interrupt is shutdown. That problem is solved in commit bf0beec0607d > ("blk-mq: drain I/O when all CPUs in a hctx are offline"). > > However, to take advantage of that blk-mq feature, the HBA HW queuess are > required to be mapped to that of the blk-mq hctx's; to do that, the HBA HW queues > need to be exposed to the upper layer. > > In making that transition, the per-SCSI command request tags are no > longer unique per Scsi host - they are just unique per hctx. As such, the > HBA LLDD would have to generate this tag internally, which has a certain > performance overhead. > > However another problem is that blk-mq assumes the host may accept > (Scsi_host.can_queue * #hw queue) commands. In commit 6eb045e092ef ("scsi: > core: avoid host-wide host_busy counter for scsi_mq"), the Scsi host busy > counter was removed, which would stop the LLDD being sent more than > .can_queue commands; however, it should still be ensured that the block > layer does not issue more than .can_queue commands to the Scsi host. > > To solve this problem, introduce a shared sbitmap per blk_mq_tag_set, > which may be requested at init time. > > New flag BLK_MQ_F_TAG_HCTX_SHARED should be set when requesting the > tagset to indicate whether the shared sbitmap should be used. > > Even when BLK_MQ_F_TAG_HCTX_SHARED is set, a full set of tags and requests > are still allocated per hctx; the reason for this is that if tags and > requests were only allocated for a single hctx - like hctx0 - it may break > block drivers which expect a request be associated with a specific hctx, > i.e. not always hctx0. This will introduce extra memory usage. > > This change is based on work originally from Ming Lei in [1] and from > Bart's suggestion in [2]. > > [0] https://lore.kernel.org/linux-block/alpine.DEB.2.21.1904051331270.1802@nanos.tec.linutronix.de/ > [1] https://lore.kernel.org/linux-block/20190531022801.10003-1-ming.lei@redhat.com/ > [2] https://lore.kernel.org/linux-block/ff77beff-5fd9-9f05-12b6-826922bace1f@huawei.com/T/#m3db0a602f095cbcbff27e9c884d6b4ae826144be > > Signed-off-by: John Garry <john.garry@huawei.com> > --- > block/blk-mq-tag.c | 39 +++++++++++++++++++++++++++++++++++++-- > block/blk-mq-tag.h | 10 +++++++++- > block/blk-mq.c | 24 +++++++++++++++++++++++- > block/blk-mq.h | 5 +++++ > include/linux/blk-mq.h | 6 ++++++ > 5 files changed, 80 insertions(+), 4 deletions(-) > > diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c > index be39db3c88d7..92843e3e1a2a 100644 > --- a/block/blk-mq-tag.c > +++ b/block/blk-mq-tag.c > @@ -228,7 +228,7 @@ static bool bt_iter(struct sbitmap *bitmap, unsigned int bitnr, void *data) > * We can hit rq == NULL here, because the tagging functions > * test and set the bit before assigning ->rqs[]. > */ > - if (rq && rq->q == hctx->queue) > + if (rq && rq->q == hctx->queue && rq->mq_hctx == hctx) > return iter_data->fn(hctx, rq, iter_data->data, reserved); > return true; > } > @@ -466,6 +466,7 @@ static int blk_mq_init_bitmap_tags(struct blk_mq_tags *tags, > round_robin, node)) > goto free_bitmap_tags; > > + /* We later overwrite these in case of per-set shared sbitmap */ > tags->bitmap_tags = &tags->__bitmap_tags; > tags->breserved_tags = &tags->__breserved_tags; You may skip to allocate anything for blk_mq_is_sbitmap_shared(), and similar change for blk_mq_free_tags(). > > @@ -475,7 +476,32 @@ static int blk_mq_init_bitmap_tags(struct blk_mq_tags *tags, > return -ENOMEM; > } > > -struct blk_mq_tags *blk_mq_init_tags(unsigned int total_tags, > +bool blk_mq_init_shared_sbitmap(struct blk_mq_tag_set *tag_set) > +{ > + unsigned int depth = tag_set->queue_depth - tag_set->reserved_tags; > + int alloc_policy = BLK_MQ_FLAG_TO_ALLOC_POLICY(tag_set->flags); > + bool round_robin = alloc_policy == BLK_TAG_ALLOC_RR; > + int node = tag_set->numa_node; > + > + if (bt_alloc(&tag_set->__bitmap_tags, depth, round_robin, node)) > + return false; > + if (bt_alloc(&tag_set->__breserved_tags, tag_set->reserved_tags, > + round_robin, node)) > + goto free_bitmap_tags; > + return true; > +free_bitmap_tags: > + sbitmap_queue_free(&tag_set->__bitmap_tags); > + return false; > +} > + > +void blk_mq_exit_shared_sbitmap(struct blk_mq_tag_set *tag_set) > +{ > + sbitmap_queue_free(&tag_set->__bitmap_tags); > + sbitmap_queue_free(&tag_set->__breserved_tags); > +} > + > +struct blk_mq_tags *blk_mq_init_tags(struct blk_mq_tag_set *set, > + unsigned int total_tags, > unsigned int reserved_tags, > int node, int alloc_policy) > { > @@ -502,6 +528,10 @@ struct blk_mq_tags *blk_mq_init_tags(unsigned int total_tags, > > void blk_mq_free_tags(struct blk_mq_tags *tags) > { > + /* > + * Do not free tags->{bitmap, breserved}_tags, as this may point to > + * shared sbitmap > + */ > sbitmap_queue_free(&tags->__bitmap_tags); > sbitmap_queue_free(&tags->__breserved_tags); > kfree(tags); > @@ -560,6 +590,11 @@ int blk_mq_tag_update_depth(struct blk_mq_hw_ctx *hctx, > return 0; > } > > +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); > +} > + > /** > * blk_mq_unique_tag() - return a tag that is unique queue-wide > * @rq: request for which to compute a unique tag > diff --git a/block/blk-mq-tag.h b/block/blk-mq-tag.h > index cebf7a4b280a..cf39dd13a24d 100644 > --- a/block/blk-mq-tag.h > +++ b/block/blk-mq-tag.h > @@ -25,7 +25,12 @@ struct blk_mq_tags { > }; > > > -extern struct blk_mq_tags *blk_mq_init_tags(unsigned int nr_tags, unsigned int reserved_tags, int node, int alloc_policy); > +extern bool blk_mq_init_shared_sbitmap(struct blk_mq_tag_set *tag_set); > +extern void blk_mq_exit_shared_sbitmap(struct blk_mq_tag_set *tag_set); > +extern struct blk_mq_tags *blk_mq_init_tags(struct blk_mq_tag_set *tag_set, > + unsigned int nr_tags, > + unsigned int reserved_tags, > + int node, int alloc_policy); > extern void blk_mq_free_tags(struct blk_mq_tags *tags); > > extern unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data); > @@ -34,6 +39,9 @@ extern void blk_mq_put_tag(struct blk_mq_tags *tags, struct blk_mq_ctx *ctx, > extern int blk_mq_tag_update_depth(struct blk_mq_hw_ctx *hctx, > struct blk_mq_tags **tags, > unsigned int depth, bool can_grow); > +extern void blk_mq_tag_resize_shared_sbitmap(struct blk_mq_tag_set *set, > + unsigned int size); > + > extern void blk_mq_tag_wakeup_all(struct blk_mq_tags *tags, bool); > void blk_mq_queue_tag_busy_iter(struct request_queue *q, busy_iter_fn *fn, > void *priv); > diff --git a/block/blk-mq.c b/block/blk-mq.c > index 90b645c3092c..77120dd4e4d5 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -2229,7 +2229,7 @@ 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, > + tags = blk_mq_init_tags(set, nr_tags, reserved_tags, node, > BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags)); > if (!tags) > return NULL; > @@ -3349,11 +3349,28 @@ 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)) { > + if (!blk_mq_init_shared_sbitmap(set)) { > + ret = -ENOMEM; > + goto out_free_mq_rq_maps; > + } > + > + 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; > + } I am wondering why you don't put ->[bitmap|breserved]_tags initialization into blk_mq_init_shared_sbitmap(). Thanks, Ming
On 11/06/2020 04:37, Ming Lei wrote: Hi Ming, Thanks for checking this. >> bool bt_iter(struct sbitmap *bitmap, unsigned int bitnr, void *data) >> * We can hit rq == NULL here, because the tagging functions >> * test and set the bit before assigning ->rqs[]. >> */ >> - if (rq && rq->q == hctx->queue) >> + if (rq && rq->q == hctx->queue && rq->mq_hctx == hctx) >> return iter_data->fn(hctx, rq, iter_data->data, reserved); >> return true; >> } >> @@ -466,6 +466,7 @@ static int blk_mq_init_bitmap_tags(struct blk_mq_tags *tags, >> round_robin, node)) >> goto free_bitmap_tags; >> >> + /* We later overwrite these in case of per-set shared sbitmap */ >> tags->bitmap_tags = &tags->__bitmap_tags; >> tags->breserved_tags = &tags->__breserved_tags; > You may skip to allocate anything for blk_mq_is_sbitmap_shared(), and > similar change for blk_mq_free_tags(). I did try that, but it breaks scheduler tags allocation - this is common code. Maybe I can pass some flag, to avoid the allocation for case of shared sbitmap and !sched tags. Same for free path. BTW, if you check patch 7/12, I mentioned that we could use this sbitmap for iterating to get the per-hctx bitmap, instead of allocating a temp sbitmap. Maybe it's better. > >> >> @@ -475,7 +476,32 @@ static int blk_mq_init_bitmap_tags(struct blk_mq_tags *tags, >> return -ENOMEM; >> } >> >> -struct blk_mq_tags *blk_mq_init_tags(unsigned int total_tags, >> +bool blk_mq_init_shared_sbitmap(struct blk_mq_tag_set *tag_set) >> +{ >> + unsigned int depth = tag_set->queue_depth - tag_set->reserved_tags; >> + int alloc_policy = BLK_MQ_FLAG_TO_ALLOC_POLICY(tag_set->flags); >> + bool round_robin = alloc_policy == BLK_TAG_ALLOC_RR; >> + int node = tag_set->numa_node; >> + >> + if (bt_alloc(&tag_set->__bitmap_tags, depth, round_robin, node)) >> + return false; >> + if (bt_alloc(&tag_set->__breserved_tags, tag_set->reserved_tags, >> + round_robin, node)) >> + goto free_bitmap_tags; >> + return true; >> +free_bitmap_tags: >> + sbitmap_queue_free(&tag_set->__bitmap_tags); >> + return false; >> +} >> + [...] >> index 90b645c3092c..77120dd4e4d5 100644 >> --- a/block/blk-mq.c >> +++ b/block/blk-mq.c >> @@ -2229,7 +2229,7 @@ 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, >> + tags = blk_mq_init_tags(set, nr_tags, reserved_tags, node, >> BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags)); >> if (!tags) >> return NULL; >> @@ -3349,11 +3349,28 @@ 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)) { >> + if (!blk_mq_init_shared_sbitmap(set)) { >> + ret = -ENOMEM; >> + goto out_free_mq_rq_maps; >> + } >> + >> + 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; >> + } > I am wondering why you don't put ->[bitmap|breserved]_tags initialization into > blk_mq_init_shared_sbitmap(). I suppose I could. Thanks, John
diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c index be39db3c88d7..92843e3e1a2a 100644 --- a/block/blk-mq-tag.c +++ b/block/blk-mq-tag.c @@ -228,7 +228,7 @@ static bool bt_iter(struct sbitmap *bitmap, unsigned int bitnr, void *data) * We can hit rq == NULL here, because the tagging functions * test and set the bit before assigning ->rqs[]. */ - if (rq && rq->q == hctx->queue) + if (rq && rq->q == hctx->queue && rq->mq_hctx == hctx) return iter_data->fn(hctx, rq, iter_data->data, reserved); return true; } @@ -466,6 +466,7 @@ static int blk_mq_init_bitmap_tags(struct blk_mq_tags *tags, round_robin, node)) goto free_bitmap_tags; + /* We later overwrite these in case of per-set shared sbitmap */ tags->bitmap_tags = &tags->__bitmap_tags; tags->breserved_tags = &tags->__breserved_tags; @@ -475,7 +476,32 @@ static int blk_mq_init_bitmap_tags(struct blk_mq_tags *tags, return -ENOMEM; } -struct blk_mq_tags *blk_mq_init_tags(unsigned int total_tags, +bool blk_mq_init_shared_sbitmap(struct blk_mq_tag_set *tag_set) +{ + unsigned int depth = tag_set->queue_depth - tag_set->reserved_tags; + int alloc_policy = BLK_MQ_FLAG_TO_ALLOC_POLICY(tag_set->flags); + bool round_robin = alloc_policy == BLK_TAG_ALLOC_RR; + int node = tag_set->numa_node; + + if (bt_alloc(&tag_set->__bitmap_tags, depth, round_robin, node)) + return false; + if (bt_alloc(&tag_set->__breserved_tags, tag_set->reserved_tags, + round_robin, node)) + goto free_bitmap_tags; + return true; +free_bitmap_tags: + sbitmap_queue_free(&tag_set->__bitmap_tags); + return false; +} + +void blk_mq_exit_shared_sbitmap(struct blk_mq_tag_set *tag_set) +{ + sbitmap_queue_free(&tag_set->__bitmap_tags); + sbitmap_queue_free(&tag_set->__breserved_tags); +} + +struct blk_mq_tags *blk_mq_init_tags(struct blk_mq_tag_set *set, + unsigned int total_tags, unsigned int reserved_tags, int node, int alloc_policy) { @@ -502,6 +528,10 @@ struct blk_mq_tags *blk_mq_init_tags(unsigned int total_tags, void blk_mq_free_tags(struct blk_mq_tags *tags) { + /* + * Do not free tags->{bitmap, breserved}_tags, as this may point to + * shared sbitmap + */ sbitmap_queue_free(&tags->__bitmap_tags); sbitmap_queue_free(&tags->__breserved_tags); kfree(tags); @@ -560,6 +590,11 @@ int blk_mq_tag_update_depth(struct blk_mq_hw_ctx *hctx, return 0; } +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); +} + /** * blk_mq_unique_tag() - return a tag that is unique queue-wide * @rq: request for which to compute a unique tag diff --git a/block/blk-mq-tag.h b/block/blk-mq-tag.h index cebf7a4b280a..cf39dd13a24d 100644 --- a/block/blk-mq-tag.h +++ b/block/blk-mq-tag.h @@ -25,7 +25,12 @@ struct blk_mq_tags { }; -extern struct blk_mq_tags *blk_mq_init_tags(unsigned int nr_tags, unsigned int reserved_tags, int node, int alloc_policy); +extern bool blk_mq_init_shared_sbitmap(struct blk_mq_tag_set *tag_set); +extern void blk_mq_exit_shared_sbitmap(struct blk_mq_tag_set *tag_set); +extern struct blk_mq_tags *blk_mq_init_tags(struct blk_mq_tag_set *tag_set, + unsigned int nr_tags, + unsigned int reserved_tags, + int node, int alloc_policy); extern void blk_mq_free_tags(struct blk_mq_tags *tags); extern unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data); @@ -34,6 +39,9 @@ extern void blk_mq_put_tag(struct blk_mq_tags *tags, struct blk_mq_ctx *ctx, extern int blk_mq_tag_update_depth(struct blk_mq_hw_ctx *hctx, struct blk_mq_tags **tags, unsigned int depth, bool can_grow); +extern void blk_mq_tag_resize_shared_sbitmap(struct blk_mq_tag_set *set, + unsigned int size); + extern void blk_mq_tag_wakeup_all(struct blk_mq_tags *tags, bool); void blk_mq_queue_tag_busy_iter(struct request_queue *q, busy_iter_fn *fn, void *priv); diff --git a/block/blk-mq.c b/block/blk-mq.c index 90b645c3092c..77120dd4e4d5 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2229,7 +2229,7 @@ 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, + tags = blk_mq_init_tags(set, nr_tags, reserved_tags, node, BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags)); if (!tags) return NULL; @@ -3349,11 +3349,28 @@ 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)) { + if (!blk_mq_init_shared_sbitmap(set)) { + ret = -ENOMEM; + goto out_free_mq_rq_maps; + } + + 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; + } + } + 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_rq_map(set->tags[i]); out_free_mq_map: for (i = 0; i < set->nr_maps; i++) { kfree(set->map[i].mq_map); @@ -3372,6 +3389,9 @@ void blk_mq_free_tag_set(struct blk_mq_tag_set *set) for (i = 0; i < set->nr_hw_queues; i++) blk_mq_free_map_and_requests(set, i); + if (blk_mq_is_sbitmap_shared(set)) + blk_mq_exit_shared_sbitmap(set); + for (j = 0; j < set->nr_maps; j++) { kfree(set->map[j].mq_map); set->map[j].mq_map = NULL; @@ -3408,6 +3428,8 @@ 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->tags, nr, false); + if (!ret && blk_mq_is_sbitmap_shared(set)) + blk_mq_tag_resize_shared_sbitmap(set, nr); } else { ret = blk_mq_tag_update_depth(hctx, &hctx->sched_tags, nr, true); diff --git a/block/blk-mq.h b/block/blk-mq.h index a139b0631817..1a283c707215 100644 --- a/block/blk-mq.h +++ b/block/blk-mq.h @@ -158,6 +158,11 @@ struct blk_mq_alloc_data { struct blk_mq_hw_ctx *hctx; }; +static inline bool blk_mq_is_sbitmap_shared(struct blk_mq_tag_set *tag_set) +{ + return tag_set->flags & BLK_MQ_F_TAG_HCTX_SHARED; +} + static inline struct blk_mq_tags *blk_mq_tags_from_data(struct blk_mq_alloc_data *data) { if (data->flags & BLK_MQ_REQ_INTERNAL) diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index 233209e8030d..7b31cdb92a71 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -231,6 +231,9 @@ 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. + * @__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. * @tag_list_lock: Serializes tag_list accesses. @@ -250,6 +253,8 @@ struct blk_mq_tag_set { unsigned int flags; void *driver_data; + struct sbitmap_queue __bitmap_tags; + struct sbitmap_queue __breserved_tags; struct blk_mq_tags **tags; struct mutex tag_list_lock; @@ -398,6 +403,7 @@ enum { * completing IO: */ BLK_MQ_F_STACKING = 1 << 2, + BLK_MQ_F_TAG_HCTX_SHARED = 1 << 3, BLK_MQ_F_BLOCKING = 1 << 5, BLK_MQ_F_NO_SCHED = 1 << 6, BLK_MQ_F_ALLOC_POLICY_START_BIT = 8,
Some SCSI HBAs (such as HPSA, megaraid, mpt3sas, hisi_sas_v3 ..) support multiple reply queues with single hostwide tags. In addition, these drivers want to use interrupt assignment in pci_alloc_irq_vectors(PCI_IRQ_AFFINITY). However, as discussed in [0], CPU hotplug may cause in-flight IO completion to not be serviced when an interrupt is shutdown. That problem is solved in commit bf0beec0607d ("blk-mq: drain I/O when all CPUs in a hctx are offline"). However, to take advantage of that blk-mq feature, the HBA HW queuess are required to be mapped to that of the blk-mq hctx's; to do that, the HBA HW queues need to be exposed to the upper layer. In making that transition, the per-SCSI command request tags are no longer unique per Scsi host - they are just unique per hctx. As such, the HBA LLDD would have to generate this tag internally, which has a certain performance overhead. However another problem is that blk-mq assumes the host may accept (Scsi_host.can_queue * #hw queue) commands. In commit 6eb045e092ef ("scsi: core: avoid host-wide host_busy counter for scsi_mq"), the Scsi host busy counter was removed, which would stop the LLDD being sent more than .can_queue commands; however, it should still be ensured that the block layer does not issue more than .can_queue commands to the Scsi host. To solve this problem, introduce a shared sbitmap per blk_mq_tag_set, which may be requested at init time. New flag BLK_MQ_F_TAG_HCTX_SHARED should be set when requesting the tagset to indicate whether the shared sbitmap should be used. Even when BLK_MQ_F_TAG_HCTX_SHARED is set, a full set of tags and requests are still allocated per hctx; the reason for this is that if tags and requests were only allocated for a single hctx - like hctx0 - it may break block drivers which expect a request be associated with a specific hctx, i.e. not always hctx0. This will introduce extra memory usage. This change is based on work originally from Ming Lei in [1] and from Bart's suggestion in [2]. [0] https://lore.kernel.org/linux-block/alpine.DEB.2.21.1904051331270.1802@nanos.tec.linutronix.de/ [1] https://lore.kernel.org/linux-block/20190531022801.10003-1-ming.lei@redhat.com/ [2] https://lore.kernel.org/linux-block/ff77beff-5fd9-9f05-12b6-826922bace1f@huawei.com/T/#m3db0a602f095cbcbff27e9c884d6b4ae826144be Signed-off-by: John Garry <john.garry@huawei.com> --- block/blk-mq-tag.c | 39 +++++++++++++++++++++++++++++++++++++-- block/blk-mq-tag.h | 10 +++++++++- block/blk-mq.c | 24 +++++++++++++++++++++++- block/blk-mq.h | 5 +++++ include/linux/blk-mq.h | 6 ++++++ 5 files changed, 80 insertions(+), 4 deletions(-)