#include <linux/delay.h>
#include <linux/wait.h>
#include <linux/kthread.h>
+#include <linux/ktime.h>
+#include <linux/elevator.h> /* for rq_end_sector() */
#include <trace/events/block.h>
struct kthread_worker kworker;
struct task_struct *kworker_task;
+
+ /* for request-based merge heuristic in dm_request_fn() */
+ unsigned seq_rq_merge_deadline_usecs;
+ int last_rq_rw;
+ sector_t last_rq_pos;
+ ktime_t last_rq_start_time;
};
/*
*/
static unsigned reserved_rq_based_ios = RESERVED_REQUEST_BASED_IOS;
-static unsigned __dm_get_reserved_ios(unsigned *reserved_ios,
+static unsigned __dm_get_module_param(unsigned *module_param,
unsigned def, unsigned max)
{
- unsigned ios = ACCESS_ONCE(*reserved_ios);
- unsigned modified_ios = 0;
+ unsigned param = ACCESS_ONCE(*module_param);
+ unsigned modified_param = 0;
- if (!ios)
- modified_ios = def;
- else if (ios > max)
- modified_ios = max;
+ if (!param)
+ modified_param = def;
+ else if (param > max)
+ modified_param = max;
- if (modified_ios) {
- (void)cmpxchg(reserved_ios, ios, modified_ios);
- ios = modified_ios;
+ if (modified_param) {
+ (void)cmpxchg(module_param, param, modified_param);
+ param = modified_param;
}
- return ios;
+ return param;
}
unsigned dm_get_reserved_bio_based_ios(void)
{
- return __dm_get_reserved_ios(&reserved_bio_based_ios,
+ return __dm_get_module_param(&reserved_bio_based_ios,
RESERVED_BIO_BASED_IOS, RESERVED_MAX_IOS);
}
EXPORT_SYMBOL_GPL(dm_get_reserved_bio_based_ios);
unsigned dm_get_reserved_rq_based_ios(void)
{
- return __dm_get_reserved_ios(&reserved_rq_based_ios,
+ return __dm_get_module_param(&reserved_rq_based_ios,
RESERVED_REQUEST_BASED_IOS, RESERVED_MAX_IOS);
}
EXPORT_SYMBOL_GPL(dm_get_reserved_rq_based_ios);
*/
static void rq_completed(struct mapped_device *md, int rw, bool run_queue)
{
+ int nr_requests_pending;
+
atomic_dec(&md->pending[rw]);
/* nudge anyone waiting on suspend queue */
- if (!md_in_flight(md))
+ nr_requests_pending = md_in_flight(md);
+ if (!nr_requests_pending)
wake_up(&md->wait);
/*
* back into ->request_fn() could deadlock attempting to grab the
* queue lock again.
*/
- if (run_queue)
- blk_run_queue_async(md->queue);
+ if (run_queue) {
+ if (!nr_requests_pending ||
+ (nr_requests_pending >= md->queue->nr_congestion_on))
+ blk_run_queue_async(md->queue);
+ }
/*
* dm_put() must be at the end of this function. See the comment above
* The request function that just remaps the bio built up by
* dm_merge_bvec.
*/
-static void _dm_request(struct request_queue *q, struct bio *bio)
+static void dm_make_request(struct request_queue *q, struct bio *bio)
{
int rw = bio_data_dir(bio);
struct mapped_device *md = q->queuedata;
return blk_queue_stackable(md->queue);
}
-static void dm_request(struct request_queue *q, struct bio *bio)
-{
- struct mapped_device *md = q->queuedata;
-
- if (dm_request_based(md))
- blk_queue_bio(q, bio);
- else
- _dm_request(q, bio);
-}
-
static void dm_dispatch_clone_request(struct request *clone, struct request *rq)
{
int r;
blk_start_request(orig);
atomic_inc(&md->pending[rq_data_dir(orig)]);
+ if (md->seq_rq_merge_deadline_usecs) {
+ md->last_rq_pos = rq_end_sector(orig);
+ md->last_rq_rw = rq_data_dir(orig);
+ md->last_rq_start_time = ktime_get();
+ }
+
/*
* Hold the md reference here for the in-flight I/O.
* We can't rely on the reference count by device opener,
dm_get(md);
}
+#define MAX_SEQ_RQ_MERGE_DEADLINE_USECS 100000
+
+ssize_t dm_attr_rq_based_seq_io_merge_deadline_show(struct mapped_device *md, char *buf)
+{
+ return sprintf(buf, "%u\n", md->seq_rq_merge_deadline_usecs);
+}
+
+ssize_t dm_attr_rq_based_seq_io_merge_deadline_store(struct mapped_device *md,
+ const char *buf, size_t count)
+{
+ unsigned deadline;
+
+ if (!dm_request_based(md))
+ return count;
+
+ if (kstrtouint(buf, 10, &deadline))
+ return -EINVAL;
+
+ if (deadline > MAX_SEQ_RQ_MERGE_DEADLINE_USECS)
+ deadline = MAX_SEQ_RQ_MERGE_DEADLINE_USECS;
+
+ md->seq_rq_merge_deadline_usecs = deadline;
+
+ return count;
+}
+
+static bool dm_request_peeked_before_merge_deadline(struct mapped_device *md)
+{
+ ktime_t kt_deadline;
+
+ if (!md->seq_rq_merge_deadline_usecs)
+ return false;
+
+ kt_deadline = ns_to_ktime((u64)md->seq_rq_merge_deadline_usecs * NSEC_PER_USEC);
+ kt_deadline = ktime_add_safe(md->last_rq_start_time, kt_deadline);
+
+ return !ktime_after(ktime_get(), kt_deadline);
+}
+
/*
* q->request_fn for request-based dm.
* Called with the queue lock held.
while (!blk_queue_stopped(q)) {
rq = blk_peek_request(q);
if (!rq)
- goto delay_and_out;
+ goto out;
/* always use block 0 to find the target for flushes for now */
pos = 0;
continue;
}
+ if (dm_request_peeked_before_merge_deadline(md) &&
+ md_in_flight(md) && rq->bio && rq->bio->bi_vcnt == 1 &&
+ md->last_rq_pos == pos && md->last_rq_rw == rq_data_dir(rq))
+ goto delay_and_out;
+
if (ti->type->busy && ti->type->busy(ti))
goto delay_and_out;
goto out;
delay_and_out:
- blk_delay_queue(q, HZ / 10);
+ blk_delay_queue(q, HZ / 100);
out:
dm_put_live_table(md, srcu_idx);
}
-int dm_underlying_device_busy(struct request_queue *q)
-{
- return blk_lld_busy(q);
-}
-EXPORT_SYMBOL_GPL(dm_underlying_device_busy);
-
-static int dm_lld_busy(struct request_queue *q)
-{
- int r;
- struct mapped_device *md = q->queuedata;
- struct dm_table *map = dm_get_live_table_fast(md);
-
- if (!map || test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags))
- r = 1;
- else
- r = dm_table_any_busy_target(map);
-
- dm_put_live_table_fast(md);
-
- return r;
-}
-
static int dm_any_congested(void *congested_data, int bdi_bits)
{
int r = bdi_bits;
md->queue->queuedata = md;
md->queue->backing_dev_info.congested_fn = dm_any_congested;
md->queue->backing_dev_info.congested_data = md;
- blk_queue_make_request(md->queue, dm_request);
+
blk_queue_bounce_limit(md->queue, BLK_BOUNCE_ANY);
- blk_queue_merge_bvec(md->queue, dm_merge_bvec);
}
/*
if (!q->merge_bvec_fn)
return 0;
- if (q->make_request_fn == dm_request) {
+ if (q->make_request_fn == dm_make_request) {
dev_md = q->queuedata;
if (test_bit(DMF_MERGE_IS_OPTIONAL, &dev_md->flags))
return 0;
if (!q)
return 0;
+ /* disable dm_request_fn's merge heuristic by default */
+ md->seq_rq_merge_deadline_usecs = 0;
+
md->queue = q;
dm_init_md_queue(md);
blk_queue_softirq_done(md->queue, dm_softirq_done);
blk_queue_prep_rq(md->queue, dm_prep_fn);
- blk_queue_lld_busy(md->queue, dm_lld_busy);
/* Also initialize the request-based DM worker thread */
init_kthread_worker(&md->kworker);
*/
int dm_setup_md_queue(struct mapped_device *md)
{
- if (dm_md_type_request_based(md) && !dm_init_request_based_queue(md)) {
- DMWARN("Cannot initialize queue for request-based mapped device");
- return -EINVAL;
+ if (dm_md_type_request_based(md)) {
+ if (!dm_init_request_based_queue(md)) {
+ DMWARN("Cannot initialize queue for request-based mapped device");
+ return -EINVAL;
+ }
+ } else {
+ /* bio-based specific initialization */
+ blk_queue_make_request(md->queue, dm_make_request);
+ blk_queue_merge_bvec(md->queue, dm_merge_bvec);
}
return 0;
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