Move the poll flag into the queue_limits feature field so that it
can be set atomically and all I/O is frozen when changing the flag.
Stacking drivers are simplified in that they now can simply set the
flag, and blk_stack_limits will clear it when the features is not
supported by any of the underlying devices.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
block/blk-core.c | 5 ++--
block/blk-mq-debugfs.c | 1 -
block/blk-mq.c | 31 +++++++++++---------
block/blk-settings.c | 10 ++++---
block/blk-sysfs.c | 4 +--
drivers/md/dm-table.c | 54 +++++++++--------------------------
drivers/nvme/host/multipath.c | 12 +-------
include/linux/blkdev.h | 4 ++-
8 files changed, 45 insertions(+), 76 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index 2b45a4df9a1aa1..8d9fbd353fc7fc 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -791,7 +791,7 @@ void submit_bio_noacct(struct bio *bio)
}
}
- if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
+ if (!(q->limits.features & BLK_FEAT_POLL))
bio_clear_polled(bio);
switch (bio_op(bio)) {
@@ -915,8 +915,7 @@ int bio_poll(struct bio *bio, struct io_comp_batch *iob, unsigned int flags)
return 0;
q = bdev_get_queue(bdev);
- if (cookie == BLK_QC_T_NONE ||
- !test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
+ if (cookie == BLK_QC_T_NONE || !(q->limits.features & BLK_FEAT_POLL))
return 0;
blk_flush_plug(current->plug, false);
diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index f4fa820251ce83..3a21527913840d 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -87,7 +87,6 @@ static const char *const blk_queue_flag_name[] = {
QUEUE_FLAG_NAME(NOXMERGES),
QUEUE_FLAG_NAME(SAME_FORCE),
QUEUE_FLAG_NAME(INIT_DONE),
- QUEUE_FLAG_NAME(POLL),
QUEUE_FLAG_NAME(STATS),
QUEUE_FLAG_NAME(REGISTERED),
QUEUE_FLAG_NAME(QUIESCED),
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 43235acc87505f..e2b9710ddc5ad1 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -4109,6 +4109,12 @@ void blk_mq_release(struct request_queue *q)
blk_mq_sysfs_deinit(q);
}
+static bool blk_mq_can_poll(struct blk_mq_tag_set *set)
+{
+ return set->nr_maps > HCTX_TYPE_POLL &&
+ set->map[HCTX_TYPE_POLL].nr_queues;
+}
+
struct request_queue *blk_mq_alloc_queue(struct blk_mq_tag_set *set,
struct queue_limits *lim, void *queuedata)
{
@@ -4119,6 +4125,8 @@ struct request_queue *blk_mq_alloc_queue(struct blk_mq_tag_set *set,
if (!lim)
lim = &default_lim;
lim->features |= BLK_FEAT_IO_STAT | BLK_FEAT_NOWAIT;
+ if (blk_mq_can_poll(set))
+ lim->features |= BLK_FEAT_POLL;
q = blk_alloc_queue(lim, set->numa_node);
if (IS_ERR(q))
@@ -4273,17 +4281,6 @@ static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
mutex_unlock(&q->sysfs_lock);
}
-static void blk_mq_update_poll_flag(struct request_queue *q)
-{
- struct blk_mq_tag_set *set = q->tag_set;
-
- if (set->nr_maps > HCTX_TYPE_POLL &&
- set->map[HCTX_TYPE_POLL].nr_queues)
- blk_queue_flag_set(QUEUE_FLAG_POLL, q);
- else
- blk_queue_flag_clear(QUEUE_FLAG_POLL, q);
-}
-
int blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
struct request_queue *q)
{
@@ -4311,7 +4308,6 @@ int blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
q->tag_set = set;
q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
- blk_mq_update_poll_flag(q);
INIT_DELAYED_WORK(&q->requeue_work, blk_mq_requeue_work);
INIT_LIST_HEAD(&q->flush_list);
@@ -4798,8 +4794,10 @@ static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set,
fallback:
blk_mq_update_queue_map(set);
list_for_each_entry(q, &set->tag_list, tag_set_list) {
+ struct queue_limits lim;
+
blk_mq_realloc_hw_ctxs(set, q);
- blk_mq_update_poll_flag(q);
+
if (q->nr_hw_queues != set->nr_hw_queues) {
int i = prev_nr_hw_queues;
@@ -4811,6 +4809,13 @@ static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set,
set->nr_hw_queues = prev_nr_hw_queues;
goto fallback;
}
+ lim = queue_limits_start_update(q);
+ if (blk_mq_can_poll(set))
+ lim.features |= BLK_FEAT_POLL;
+ else
+ lim.features &= ~BLK_FEAT_POLL;
+ if (queue_limits_commit_update(q, &lim) < 0)
+ pr_warn("updating the poll flag failed\n");
blk_mq_map_swqueue(q);
}
diff --git a/block/blk-settings.c b/block/blk-settings.c
index bf4622c19b5c09..026ba68d829856 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -460,13 +460,15 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
t->features |= (b->features & BLK_FEAT_INHERIT_MASK);
/*
- * BLK_FEAT_NOWAIT needs to be supported both by the stacking driver
- * and all underlying devices. The stacking driver sets the flag
- * before stacking the limits, and this will clear the flag if any
- * of the underlying devices does not support it.
+ * BLK_FEAT_NOWAIT and BLK_FEAT_POLL need to be supported both by the
+ * stacking driver and all underlying devices. The stacking driver sets
+ * the flags before stacking the limits, and this will clear the flags
+ * if any of the underlying devices does not support it.
*/
if (!(b->features & BLK_FEAT_NOWAIT))
t->features &= ~BLK_FEAT_NOWAIT;
+ if (!(b->features & BLK_FEAT_POLL))
+ t->features &= ~BLK_FEAT_POLL;
t->max_sectors = min_not_zero(t->max_sectors, b->max_sectors);
t->max_user_sectors = min_not_zero(t->max_user_sectors,
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index cde525724831ef..da4e96d686f91e 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -394,13 +394,13 @@ static ssize_t queue_poll_delay_store(struct request_queue *q, const char *page,
static ssize_t queue_poll_show(struct request_queue *q, char *page)
{
- return queue_var_show(test_bit(QUEUE_FLAG_POLL, &q->queue_flags), page);
+ return queue_var_show(q->limits.features & BLK_FEAT_POLL, page);
}
static ssize_t queue_poll_store(struct request_queue *q, const char *page,
size_t count)
{
- if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
+ if (!(q->limits.features & BLK_FEAT_POLL))
return -EINVAL;
pr_info_ratelimited("writes to the poll attribute are ignored.\n");
pr_info_ratelimited("please use driver specific parameters instead.\n");
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index d3a960aee03c6a..653c253b6f7f32 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -582,7 +582,7 @@ int dm_split_args(int *argc, char ***argvp, char *input)
static void dm_set_stacking_limits(struct queue_limits *limits)
{
blk_set_stacking_limits(limits);
- limits->features |= BLK_FEAT_IO_STAT | BLK_FEAT_NOWAIT;
+ limits->features |= BLK_FEAT_IO_STAT | BLK_FEAT_NOWAIT | BLK_FEAT_POLL;
}
/*
@@ -1024,14 +1024,13 @@ bool dm_table_request_based(struct dm_table *t)
return __table_type_request_based(dm_table_get_type(t));
}
-static bool dm_table_supports_poll(struct dm_table *t);
-
static int dm_table_alloc_md_mempools(struct dm_table *t, struct mapped_device *md)
{
enum dm_queue_mode type = dm_table_get_type(t);
unsigned int per_io_data_size = 0, front_pad, io_front_pad;
unsigned int min_pool_size = 0, pool_size;
struct dm_md_mempools *pools;
+ unsigned int bioset_flags = 0;
if (unlikely(type == DM_TYPE_NONE)) {
DMERR("no table type is set, can't allocate mempools");
@@ -1048,6 +1047,9 @@ static int dm_table_alloc_md_mempools(struct dm_table *t, struct mapped_device *
goto init_bs;
}
+ if (md->queue->limits.features & BLK_FEAT_POLL)
+ bioset_flags |= BIOSET_PERCPU_CACHE;
+
for (unsigned int i = 0; i < t->num_targets; i++) {
struct dm_target *ti = dm_table_get_target(t, i);
@@ -1060,8 +1062,7 @@ static int dm_table_alloc_md_mempools(struct dm_table *t, struct mapped_device *
io_front_pad = roundup(per_io_data_size,
__alignof__(struct dm_io)) + DM_IO_BIO_OFFSET;
- if (bioset_init(&pools->io_bs, pool_size, io_front_pad,
- dm_table_supports_poll(t) ? BIOSET_PERCPU_CACHE : 0))
+ if (bioset_init(&pools->io_bs, pool_size, io_front_pad, bioset_flags))
goto out_free_pools;
if (t->integrity_supported &&
bioset_integrity_create(&pools->io_bs, pool_size))
@@ -1404,14 +1405,6 @@ struct dm_target *dm_table_find_target(struct dm_table *t, sector_t sector)
return &t->targets[(KEYS_PER_NODE * n) + k];
}
-static int device_not_poll_capable(struct dm_target *ti, struct dm_dev *dev,
- sector_t start, sector_t len, void *data)
-{
- struct request_queue *q = bdev_get_queue(dev->bdev);
-
- return !test_bit(QUEUE_FLAG_POLL, &q->queue_flags);
-}
-
/*
* type->iterate_devices() should be called when the sanity check needs to
* iterate and check all underlying data devices. iterate_devices() will
@@ -1459,19 +1452,6 @@ static int count_device(struct dm_target *ti, struct dm_dev *dev,
return 0;
}
-static bool dm_table_supports_poll(struct dm_table *t)
-{
- for (unsigned int i = 0; i < t->num_targets; i++) {
- struct dm_target *ti = dm_table_get_target(t, i);
-
- if (!ti->type->iterate_devices ||
- ti->type->iterate_devices(ti, device_not_poll_capable, NULL))
- return false;
- }
-
- return true;
-}
-
/*
* Check whether a table has no data devices attached using each
* target's iterate_devices method.
@@ -1817,6 +1797,13 @@ int dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
if (dm_table_supports_nowait(t))
limits->features &= ~BLK_FEAT_NOWAIT;
+ /*
+ * The current polling impementation does not support request based
+ * stacking.
+ */
+ if (!__table_type_bio_based(t->type))
+ limits->features &= ~BLK_FEAT_POLL;
+
if (!dm_table_supports_discards(t)) {
limits->max_hw_discard_sectors = 0;
limits->discard_granularity = 0;
@@ -1858,21 +1845,6 @@ int dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
return r;
dm_update_crypto_profile(q, t);
-
- /*
- * Check for request-based device is left to
- * dm_mq_init_request_queue()->blk_mq_init_allocated_queue().
- *
- * For bio-based device, only set QUEUE_FLAG_POLL when all
- * underlying devices supporting polling.
- */
- if (__table_type_bio_based(t->type)) {
- if (dm_table_supports_poll(t))
- blk_queue_flag_set(QUEUE_FLAG_POLL, q);
- else
- blk_queue_flag_clear(QUEUE_FLAG_POLL, q);
- }
-
return 0;
}
diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index 61a162c9cf4e6c..4933194d00e592 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -538,7 +538,7 @@ int nvme_mpath_alloc_disk(struct nvme_ctrl *ctrl, struct nvme_ns_head *head)
blk_set_stacking_limits(&lim);
lim.dma_alignment = 3;
- lim.features |= BLK_FEAT_IO_STAT | BLK_FEAT_NOWAIT;
+ lim.features |= BLK_FEAT_IO_STAT | BLK_FEAT_NOWAIT | BLK_FEAT_POLL;
if (head->ids.csi != NVME_CSI_ZNS)
lim.max_zone_append_sectors = 0;
@@ -549,16 +549,6 @@ int nvme_mpath_alloc_disk(struct nvme_ctrl *ctrl, struct nvme_ns_head *head)
head->disk->private_data = head;
sprintf(head->disk->disk_name, "nvme%dn%d",
ctrl->subsys->instance, head->instance);
-
- /*
- * This assumes all controllers that refer to a namespace either
- * support poll queues or not. That is not a strict guarantee,
- * but if the assumption is wrong the effect is only suboptimal
- * performance but not correctness problem.
- */
- if (ctrl->tagset->nr_maps > HCTX_TYPE_POLL &&
- ctrl->tagset->map[HCTX_TYPE_POLL].nr_queues)
- blk_queue_flag_set(QUEUE_FLAG_POLL, head->disk->queue);
return 0;
}
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index c2545580c5b134..d0db354b12db47 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -310,6 +310,9 @@ enum {
/* supports DAX */
BLK_FEAT_DAX = (1u << 8),
+
+ /* supports I/O polling */
+ BLK_FEAT_POLL = (1u << 9),
};
/*
@@ -577,7 +580,6 @@ struct request_queue {
#define QUEUE_FLAG_NOXMERGES 9 /* No extended merges */
#define QUEUE_FLAG_SAME_FORCE 12 /* force complete on same CPU */
#define QUEUE_FLAG_INIT_DONE 14 /* queue is initialized */
-#define QUEUE_FLAG_POLL 16 /* IO polling enabled if set */
#define QUEUE_FLAG_STATS 20 /* track IO start and completion times */
#define QUEUE_FLAG_REGISTERED 22 /* queue has been registered to a disk */
#define QUEUE_FLAG_QUIESCED 24 /* queue has been quiesced */
--
2.43.0
