target: cleanup iblock bio submission

Move the entirely bio allocation, mapping and submission into ->do_task.
This

 a) avoids blocking the I/O submission thread unessecarily, and
 b) simplifies the code greatly

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
This commit is contained in:
Christoph Hellwig 2011-09-25 14:56:24 -04:00 committed by Nicholas Bellinger
parent b6b4e61ff4
commit dbbf3e94c2
2 changed files with 59 additions and 136 deletions

View File

@ -374,45 +374,6 @@ static int iblock_emulated_fua_read(struct se_device *dev)
return 0;
}
static int iblock_do_task(struct se_task *task)
{
struct se_device *dev = task->task_se_cmd->se_dev;
struct iblock_req *req = IBLOCK_REQ(task);
struct bio *bio = req->ib_bio, *nbio = NULL;
struct blk_plug plug;
int rw;
if (task->task_data_direction == DMA_TO_DEVICE) {
/*
* Force data to disk if we pretend to not have a volatile
* write cache, or the initiator set the Force Unit Access bit.
*/
if (dev->se_sub_dev->se_dev_attrib.emulate_write_cache == 0 ||
(dev->se_sub_dev->se_dev_attrib.emulate_fua_write > 0 &&
task->task_se_cmd->t_tasks_fua))
rw = WRITE_FUA;
else
rw = WRITE;
} else {
rw = READ;
}
blk_start_plug(&plug);
while (bio) {
nbio = bio->bi_next;
bio->bi_next = NULL;
pr_debug("Calling submit_bio() task: %p bio: %p"
" bio->bi_sector: %llu\n", task, bio,
(unsigned long long)bio->bi_sector);
submit_bio(rw, bio);
bio = nbio;
}
blk_finish_plug(&plug);
return PYX_TRANSPORT_SENT_TO_TRANSPORT;
}
static int iblock_do_discard(struct se_device *dev, sector_t lba, u32 range)
{
struct iblock_dev *ibd = dev->dev_ptr;
@ -424,20 +385,7 @@ static int iblock_do_discard(struct se_device *dev, sector_t lba, u32 range)
static void iblock_free_task(struct se_task *task)
{
struct iblock_req *req = IBLOCK_REQ(task);
struct bio *bio, *hbio = req->ib_bio;
/*
* We only release the bio(s) here if iblock_bio_done() has not called
* bio_put() -> iblock_bio_destructor().
*/
while (hbio != NULL) {
bio = hbio;
hbio = hbio->bi_next;
bio->bi_next = NULL;
bio_put(bio);
}
kfree(req);
kfree(IBLOCK_REQ(task));
}
enum {
@ -556,20 +504,16 @@ static void iblock_bio_destructor(struct bio *bio)
bio_free(bio, ib_dev->ibd_bio_set);
}
static struct bio *iblock_get_bio(
struct se_task *task,
struct iblock_req *ib_req,
struct iblock_dev *ib_dev,
int *ret,
sector_t lba,
u32 sg_num)
static struct bio *
iblock_get_bio(struct se_task *task, sector_t lba, u32 sg_num)
{
struct iblock_dev *ib_dev = task->se_dev->dev_ptr;
struct iblock_req *ib_req = IBLOCK_REQ(task);
struct bio *bio;
bio = bio_alloc_bioset(GFP_NOIO, sg_num, ib_dev->ibd_bio_set);
if (!bio) {
pr_err("Unable to allocate memory for bio\n");
*ret = PYX_TRANSPORT_OUT_OF_MEMORY_RESOURCES;
return NULL;
}
@ -590,17 +534,33 @@ static struct bio *iblock_get_bio(
return bio;
}
static int iblock_map_data_SG(struct se_task *task)
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_dev *ib_dev = task->se_dev->dev_ptr;
struct iblock_req *ib_req = IBLOCK_REQ(task);
struct bio *bio = NULL, *hbio = NULL, *tbio = NULL;
struct bio *bio;
struct bio_list list;
struct scatterlist *sg;
int ret = 0;
u32 i, sg_num = task->task_sg_nents;
sector_t block_lba;
struct blk_plug plug;
int rw;
if (task->task_data_direction == DMA_TO_DEVICE) {
/*
* Force data to disk if we pretend to not have a volatile
* write cache, or the initiator set the Force Unit Access bit.
*/
if (dev->se_sub_dev->se_dev_attrib.emulate_write_cache == 0 ||
(dev->se_sub_dev->se_dev_attrib.emulate_fua_write > 0 &&
task->task_se_cmd->t_tasks_fua))
rw = WRITE_FUA;
else
rw = WRITE;
} else {
rw = READ;
}
/*
* Do starting conversion up from non 512-byte blocksize with
* struct se_task SCSI blocksize into Linux/Block 512 units for BIO.
@ -619,63 +579,43 @@ static int iblock_map_data_SG(struct se_task *task)
return PYX_TRANSPORT_LU_COMM_FAILURE;
}
bio = iblock_get_bio(task, ib_req, ib_dev, &ret, block_lba, sg_num);
bio = iblock_get_bio(task, block_lba, sg_num);
if (!bio)
return ret;
return PYX_TRANSPORT_OUT_OF_MEMORY_RESOURCES;
bio_list_init(&list);
bio_list_add(&list, bio);
ib_req->ib_bio = bio;
hbio = tbio = bio;
/*
* Use fs/bio.c:bio_add_pages() to setup the bio_vec maplist
* from task->task_sg -> struct scatterlist memory.
*/
for_each_sg(task->task_sg, sg, task->task_sg_nents, i) {
pr_debug("task: %p bio: %p Calling bio_add_page(): page:"
" %p len: %u offset: %u\n", task, bio, sg_page(sg),
sg->length, sg->offset);
again:
ret = bio_add_page(bio, sg_page(sg), sg->length, sg->offset);
if (ret != sg->length) {
pr_debug("*** Set bio->bi_sector: %llu\n",
(unsigned long long)bio->bi_sector);
pr_debug("** task->task_size: %u\n",
task->task_size);
pr_debug("*** bio->bi_max_vecs: %u\n",
bio->bi_max_vecs);
pr_debug("*** bio->bi_vcnt: %u\n",
bio->bi_vcnt);
bio = iblock_get_bio(task, ib_req, ib_dev, &ret,
block_lba, sg_num);
/*
* XXX: if the length the device accepts is shorter than the
* length of the S/G list entry this will cause and
* endless loop. Better hope no driver uses huge pages.
*/
while (bio_add_page(bio, sg_page(sg), sg->length, sg->offset)
!= sg->length) {
bio = iblock_get_bio(task, block_lba, sg_num);
if (!bio)
goto fail;
tbio = tbio->bi_next = bio;
pr_debug("-----------------> Added +1 bio: %p to"
" list, Going to again\n", bio);
goto again;
bio_list_add(&list, bio);
}
/* Always in 512 byte units for Linux/Block */
block_lba += sg->length >> IBLOCK_LBA_SHIFT;
sg_num--;
pr_debug("task: %p bio-add_page() passed!, decremented"
" sg_num to %u\n", task, sg_num);
pr_debug("task: %p bio_add_page() passed!, increased lba"
" to %llu\n", task, (unsigned long long)block_lba);
pr_debug("task: %p bio_add_page() passed!, bio->bi_vcnt:"
" %u\n", task, bio->bi_vcnt);
}
return 0;
blk_start_plug(&plug);
while ((bio = bio_list_pop(&list)))
submit_bio(rw, bio);
blk_finish_plug(&plug);
return PYX_TRANSPORT_SENT_TO_TRANSPORT;
fail:
while (hbio) {
bio = hbio;
hbio = hbio->bi_next;
bio->bi_next = NULL;
while ((bio = bio_list_pop(&list)))
bio_put(bio);
}
return ret;
return PYX_TRANSPORT_OUT_OF_MEMORY_RESOURCES;
}
static unsigned char *iblock_get_cdb(struct se_task *task)
@ -706,6 +646,7 @@ static void iblock_bio_done(struct bio *bio, int err)
{
struct se_task *task = bio->bi_private;
struct iblock_req *ibr = IBLOCK_REQ(task);
/*
* Set -EIO if !BIO_UPTODATE and the passed is still err=0
*/
@ -720,41 +661,24 @@ static void iblock_bio_done(struct bio *bio, int err)
*/
atomic_inc(&ibr->ib_bio_err_cnt);
smp_mb__after_atomic_inc();
bio_put(bio);
/*
* Wait to complete the task until the last bio as completed.
*/
if (!atomic_dec_and_test(&ibr->ib_bio_cnt))
return;
ibr->ib_bio = NULL;
transport_complete_task(task, 0);
return;
}
pr_debug("done[%p] bio: %p task_lba: %llu bio_lba: %llu err=%d\n",
task, bio, task->task_lba, (unsigned long long)bio->bi_sector, err);
/*
* bio_put() will call iblock_bio_destructor() to release the bio back
* to ibr->ib_bio_set.
*/
bio_put(bio);
/*
* Wait to complete the task until the last bio as completed.
*/
if (!atomic_dec_and_test(&ibr->ib_bio_cnt))
return;
/*
* Return GOOD status for task if zero ib_bio_err_cnt exists.
*/
ibr->ib_bio = NULL;
transport_complete_task(task, (!atomic_read(&ibr->ib_bio_err_cnt)));
pr_debug("done[%p] bio: %p task_lba: %llu bio_lba: %llu err=%d\n",
task, bio, task->task_lba,
(unsigned long long)bio->bi_sector, err);
transport_complete_task(task, !atomic_read(&ibr->ib_bio_err_cnt));
}
static struct se_subsystem_api iblock_template = {
.name = "iblock",
.owner = THIS_MODULE,
.transport_type = TRANSPORT_PLUGIN_VHBA_PDEV,
.map_data_SG = iblock_map_data_SG,
.attach_hba = iblock_attach_hba,
.detach_hba = iblock_detach_hba,
.allocate_virtdevice = iblock_allocate_virtdevice,

View File

@ -11,7 +11,6 @@ struct iblock_req {
unsigned char ib_scsi_cdb[TCM_MAX_COMMAND_SIZE];
atomic_t ib_bio_cnt;
atomic_t ib_bio_err_cnt;
struct bio *ib_bio;
} ____cacheline_aligned;
#define IBDF_HAS_UDEV_PATH 0x01