There is no real limit for task sizes in the iblock driver given that we
can chain bios. Increase the maximum size to UINT_MAX, and change the
code to submit bios in a smaller batch size to avoid deadlocks when
having more bios in flight than the pool supports. Also increase the
pool size to always allow multiple tasks to be in flight.
I also had to change the task refcounting to include one reference for
the submission task, which is a standard practice in this kind of code
in Linux (e.g. XFS I/O submission). This was wrong before, but couldn't
be hit easily.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Index: lio-core/drivers/target/target_core_iblock.c
===================================================================
--- lio-core.orig/drivers/target/target_core_iblock.c 2011-12-12 04:51:55.746662134 -0800
+++ lio-core/drivers/target/target_core_iblock.c 2011-12-12 05:25:13.156650201 -0800
@@ -46,6 +46,9 @@
#include "target_core_iblock.h"
+#define IBLOCK_MAX_BIO_PER_TASK 32 /* max # of bios to submit at a time */
+#define IBLOCK_BIO_POOL_SIZE 128
+
static struct se_subsystem_api iblock_template;
static void iblock_bio_done(struct bio *, int);
@@ -100,10 +103,8 @@ static struct se_device *iblock_create_v
return ERR_PTR(ret);
}
memset(&dev_limits, 0, sizeof(struct se_dev_limits));
- /*
- * These settings need to be made tunable..
- */
- ib_dev->ibd_bio_set = bioset_create(32, 0);
+
+ ib_dev->ibd_bio_set = bioset_create(IBLOCK_BIO_POOL_SIZE, 0);
if (!ib_dev->ibd_bio_set) {
pr_err("IBLOCK: Unable to create bioset()\n");
return ERR_PTR(-ENOMEM);
@@ -129,8 +130,8 @@ static struct se_device *iblock_create_v
q = bdev_get_queue(bd);
limits = &dev_limits.limits;
limits->logical_block_size = bdev_logical_block_size(bd);
- limits->max_hw_sectors = queue_max_hw_sectors(q);
- limits->max_sectors = queue_max_sectors(q);
+ limits->max_hw_sectors = UINT_MAX;
+ limits->max_sectors = UINT_MAX;
dev_limits.hw_queue_depth = q->nr_requests;
dev_limits.queue_depth = q->nr_requests;
@@ -204,7 +205,7 @@ iblock_alloc_task(unsigned char *cdb)
return NULL;
}
- atomic_set(&ib_req->ib_bio_cnt, 0);
+ atomic_set(&ib_req->pending, 1);
return &ib_req->ib_task;
}
@@ -477,24 +478,35 @@ iblock_get_bio(struct se_task *task, sec
bio->bi_destructor = iblock_bio_destructor;
bio->bi_end_io = &iblock_bio_done;
bio->bi_sector = lba;
- atomic_inc(&ib_req->ib_bio_cnt);
+ atomic_inc(&ib_req->pending);
pr_debug("Set bio->bi_sector: %llu\n", (unsigned long long)bio->bi_sector);
- pr_debug("Set ib_req->ib_bio_cnt: %d\n",
- atomic_read(&ib_req->ib_bio_cnt));
+ pr_debug("Set ib_req->pending: %d\n", atomic_read(&ib_req->pending));
return bio;
}
+static void iblock_submit_bios(struct bio_list *list, int rw)
+{
+ struct blk_plug plug;
+ struct bio *bio;
+
+ blk_start_plug(&plug);
+ while ((bio = bio_list_pop(list)))
+ submit_bio(rw, bio);
+ blk_finish_plug(&plug);
+}
+
static int iblock_do_task(struct se_task *task)
{
struct se_cmd *cmd = task->task_se_cmd;
struct se_device *dev = cmd->se_dev;
+ struct iblock_req *ibr = IBLOCK_REQ(task);
struct bio *bio;
struct bio_list list;
struct scatterlist *sg;
u32 i, sg_num = task->task_sg_nents;
sector_t block_lba;
- struct blk_plug plug;
+ unsigned bio_cnt;
int rw;
if (task->task_data_direction == DMA_TO_DEVICE) {
@@ -539,6 +551,7 @@ static int iblock_do_task(struct se_task
bio_list_init(&list);
bio_list_add(&list, bio);
+ bio_cnt = 1;
for_each_sg(task->task_sg, sg, task->task_sg_nents, i) {
/*
@@ -548,10 +561,16 @@ static int iblock_do_task(struct se_task
*/
while (bio_add_page(bio, sg_page(sg), sg->length, sg->offset)
!= sg->length) {
+ if (bio_cnt >= IBLOCK_MAX_BIO_PER_TASK) {
+ iblock_submit_bios(&list, rw);
+ bio_cnt = 0;
+ }
+
bio = iblock_get_bio(task, block_lba, sg_num);
if (!bio)
goto fail;
bio_list_add(&list, bio);
+ bio_cnt++;
}
/* Always in 512 byte units for Linux/Block */
@@ -559,11 +578,12 @@ static int iblock_do_task(struct se_task
sg_num--;
}
- blk_start_plug(&plug);
- while ((bio = bio_list_pop(&list)))
- submit_bio(rw, bio);
- blk_finish_plug(&plug);
+ iblock_submit_bios(&list, rw);
+ if (atomic_dec_and_test(&ibr->pending)) {
+ transport_complete_task(task,
+ !atomic_read(&ibr->ib_bio_err_cnt));
+ }
return 0;
fail:
@@ -615,7 +635,7 @@ static void iblock_bio_done(struct bio *
bio_put(bio);
- if (!atomic_dec_and_test(&ibr->ib_bio_cnt))
+ if (!atomic_dec_and_test(&ibr->pending))
return;
pr_debug("done[%p] bio: %p task_lba: %llu bio_lba: %llu err=%d\n",
Index: lio-core/drivers/target/target_core_iblock.h
===================================================================
--- lio-core.orig/drivers/target/target_core_iblock.h 2011-12-12 04:51:00.333329132 -0800
+++ lio-core/drivers/target/target_core_iblock.h 2011-12-12 05:24:40.423317064 -0800
@@ -8,7 +8,7 @@
struct iblock_req {
struct se_task ib_task;
- atomic_t ib_bio_cnt;
+ atomic_t pending;
atomic_t ib_bio_err_cnt;
} ____cacheline_aligned;
--
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