From: Christoph Hellwig <hch@xxxxxxxxxxxxx>
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@xxxxxx>
Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
---
drivers/target/target_core_iblock.c | 194 +++++++++++------------------------
drivers/target/target_core_iblock.h | 1 -
2 files changed, 59 insertions(+), 136 deletions(-)
diff --git a/drivers/target/target_core_iblock.c b/drivers/target/target_core_iblock.c
index 7f0cc53..dcf93f8 100644
--- a/drivers/target/target_core_iblock.c
+++ b/drivers/target/target_core_iblock.c
@@ -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,
diff --git a/drivers/target/target_core_iblock.h b/drivers/target/target_core_iblock.h
index a121cd1..7a76f66 100644
--- a/drivers/target/target_core_iblock.h
+++ b/drivers/target/target_core_iblock.h
@@ -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
--
1.5.6.5
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