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Commit d5b4a21b authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Nicholas Bellinger
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target: increase iblock task sizes 



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: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarNicholas Bellinger <nab@linux-iscsi.org>
parent 6e315a06

drivers/target/target_core_iblock.c

+36 −16
Original line number Diff line number Diff line
@@ -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_virtdevice( 
		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_virtdevice( 
	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;

}
@@ -484,24 +485,35 @@ iblock_get_bio(struct se_task *task, sector_t lba, u32 sg_num) 
	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) {
@@ -546,6 +558,7 @@ static int iblock_do_task(struct se_task *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) {

		/*
@@ -555,10 +568,16 @@ static int iblock_do_task(struct se_task *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 */
@@ -566,11 +585,12 @@ static int iblock_do_task(struct se_task *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:
@@ -622,7 +642,7 @@ static void iblock_bio_done(struct bio *bio, int err) 


	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",

drivers/target/target_core_iblock.h

+1 −1
Original line number Diff line number Diff line
@@ -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;