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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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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
Nicholas Bellinger
parent
b6b4e61ff4
commit
dbbf3e94c2
2 changed files with 59 additions and 136 deletions
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@ -374,45 +374,6 @@ static int iblock_emulated_fua_read(struct se_device *dev)
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return 0;
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}
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static int iblock_do_task(struct se_task *task)
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{
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struct se_device *dev = task->task_se_cmd->se_dev;
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struct iblock_req *req = IBLOCK_REQ(task);
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struct bio *bio = req->ib_bio, *nbio = NULL;
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struct blk_plug plug;
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int rw;
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if (task->task_data_direction == DMA_TO_DEVICE) {
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/*
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* Force data to disk if we pretend to not have a volatile
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* write cache, or the initiator set the Force Unit Access bit.
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*/
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if (dev->se_sub_dev->se_dev_attrib.emulate_write_cache == 0 ||
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(dev->se_sub_dev->se_dev_attrib.emulate_fua_write > 0 &&
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task->task_se_cmd->t_tasks_fua))
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rw = WRITE_FUA;
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else
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rw = WRITE;
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} else {
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rw = READ;
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}
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blk_start_plug(&plug);
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while (bio) {
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nbio = bio->bi_next;
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bio->bi_next = NULL;
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pr_debug("Calling submit_bio() task: %p bio: %p"
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" bio->bi_sector: %llu\n", task, bio,
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(unsigned long long)bio->bi_sector);
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submit_bio(rw, bio);
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bio = nbio;
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}
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blk_finish_plug(&plug);
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return PYX_TRANSPORT_SENT_TO_TRANSPORT;
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}
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static int iblock_do_discard(struct se_device *dev, sector_t lba, u32 range)
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{
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struct iblock_dev *ibd = dev->dev_ptr;
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@ -424,20 +385,7 @@ static int iblock_do_discard(struct se_device *dev, sector_t lba, u32 range)
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static void iblock_free_task(struct se_task *task)
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{
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struct iblock_req *req = IBLOCK_REQ(task);
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struct bio *bio, *hbio = req->ib_bio;
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/*
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* We only release the bio(s) here if iblock_bio_done() has not called
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* bio_put() -> iblock_bio_destructor().
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*/
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while (hbio != NULL) {
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bio = hbio;
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hbio = hbio->bi_next;
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bio->bi_next = NULL;
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bio_put(bio);
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}
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kfree(req);
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kfree(IBLOCK_REQ(task));
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}
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enum {
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@ -556,20 +504,16 @@ static void iblock_bio_destructor(struct bio *bio)
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bio_free(bio, ib_dev->ibd_bio_set);
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}
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static struct bio *iblock_get_bio(
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struct se_task *task,
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struct iblock_req *ib_req,
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struct iblock_dev *ib_dev,
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int *ret,
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sector_t lba,
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u32 sg_num)
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static struct bio *
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iblock_get_bio(struct se_task *task, sector_t lba, u32 sg_num)
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{
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struct iblock_dev *ib_dev = task->se_dev->dev_ptr;
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struct iblock_req *ib_req = IBLOCK_REQ(task);
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struct bio *bio;
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bio = bio_alloc_bioset(GFP_NOIO, sg_num, ib_dev->ibd_bio_set);
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if (!bio) {
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pr_err("Unable to allocate memory for bio\n");
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*ret = PYX_TRANSPORT_OUT_OF_MEMORY_RESOURCES;
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return NULL;
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}
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@ -590,17 +534,33 @@ static struct bio *iblock_get_bio(
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return bio;
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}
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static int iblock_map_data_SG(struct se_task *task)
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static int iblock_do_task(struct se_task *task)
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{
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struct se_cmd *cmd = task->task_se_cmd;
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struct se_device *dev = cmd->se_dev;
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struct iblock_dev *ib_dev = task->se_dev->dev_ptr;
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struct iblock_req *ib_req = IBLOCK_REQ(task);
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struct bio *bio = NULL, *hbio = NULL, *tbio = NULL;
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struct bio *bio;
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struct bio_list list;
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struct scatterlist *sg;
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int ret = 0;
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u32 i, sg_num = task->task_sg_nents;
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sector_t block_lba;
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struct blk_plug plug;
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int rw;
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if (task->task_data_direction == DMA_TO_DEVICE) {
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/*
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* Force data to disk if we pretend to not have a volatile
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* write cache, or the initiator set the Force Unit Access bit.
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*/
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if (dev->se_sub_dev->se_dev_attrib.emulate_write_cache == 0 ||
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(dev->se_sub_dev->se_dev_attrib.emulate_fua_write > 0 &&
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task->task_se_cmd->t_tasks_fua))
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rw = WRITE_FUA;
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else
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rw = WRITE;
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} else {
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rw = READ;
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}
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/*
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* Do starting conversion up from non 512-byte blocksize with
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* struct se_task SCSI blocksize into Linux/Block 512 units for BIO.
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@ -619,63 +579,43 @@ static int iblock_map_data_SG(struct se_task *task)
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return PYX_TRANSPORT_LU_COMM_FAILURE;
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}
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bio = iblock_get_bio(task, ib_req, ib_dev, &ret, block_lba, sg_num);
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bio = iblock_get_bio(task, block_lba, sg_num);
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if (!bio)
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return ret;
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return PYX_TRANSPORT_OUT_OF_MEMORY_RESOURCES;
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bio_list_init(&list);
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bio_list_add(&list, bio);
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ib_req->ib_bio = bio;
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hbio = tbio = bio;
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/*
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* Use fs/bio.c:bio_add_pages() to setup the bio_vec maplist
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* from task->task_sg -> struct scatterlist memory.
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*/
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for_each_sg(task->task_sg, sg, task->task_sg_nents, i) {
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pr_debug("task: %p bio: %p Calling bio_add_page(): page:"
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" %p len: %u offset: %u\n", task, bio, sg_page(sg),
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sg->length, sg->offset);
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again:
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ret = bio_add_page(bio, sg_page(sg), sg->length, sg->offset);
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if (ret != sg->length) {
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pr_debug("*** Set bio->bi_sector: %llu\n",
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(unsigned long long)bio->bi_sector);
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pr_debug("** task->task_size: %u\n",
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task->task_size);
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pr_debug("*** bio->bi_max_vecs: %u\n",
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bio->bi_max_vecs);
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pr_debug("*** bio->bi_vcnt: %u\n",
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bio->bi_vcnt);
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bio = iblock_get_bio(task, ib_req, ib_dev, &ret,
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block_lba, sg_num);
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/*
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* XXX: if the length the device accepts is shorter than the
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* length of the S/G list entry this will cause and
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* endless loop. Better hope no driver uses huge pages.
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*/
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while (bio_add_page(bio, sg_page(sg), sg->length, sg->offset)
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!= sg->length) {
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bio = iblock_get_bio(task, block_lba, sg_num);
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if (!bio)
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goto fail;
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tbio = tbio->bi_next = bio;
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pr_debug("-----------------> Added +1 bio: %p to"
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" list, Going to again\n", bio);
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goto again;
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bio_list_add(&list, bio);
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}
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/* Always in 512 byte units for Linux/Block */
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block_lba += sg->length >> IBLOCK_LBA_SHIFT;
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sg_num--;
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pr_debug("task: %p bio-add_page() passed!, decremented"
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" sg_num to %u\n", task, sg_num);
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pr_debug("task: %p bio_add_page() passed!, increased lba"
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" to %llu\n", task, (unsigned long long)block_lba);
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pr_debug("task: %p bio_add_page() passed!, bio->bi_vcnt:"
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" %u\n", task, bio->bi_vcnt);
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}
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return 0;
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blk_start_plug(&plug);
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while ((bio = bio_list_pop(&list)))
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submit_bio(rw, bio);
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blk_finish_plug(&plug);
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return PYX_TRANSPORT_SENT_TO_TRANSPORT;
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fail:
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while (hbio) {
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bio = hbio;
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hbio = hbio->bi_next;
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bio->bi_next = NULL;
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while ((bio = bio_list_pop(&list)))
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bio_put(bio);
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}
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return ret;
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return PYX_TRANSPORT_OUT_OF_MEMORY_RESOURCES;
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}
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static unsigned char *iblock_get_cdb(struct se_task *task)
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@ -706,6 +646,7 @@ static void iblock_bio_done(struct bio *bio, int err)
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{
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struct se_task *task = bio->bi_private;
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struct iblock_req *ibr = IBLOCK_REQ(task);
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/*
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* Set -EIO if !BIO_UPTODATE and the passed is still err=0
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*/
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@ -720,41 +661,24 @@ static void iblock_bio_done(struct bio *bio, int err)
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*/
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atomic_inc(&ibr->ib_bio_err_cnt);
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smp_mb__after_atomic_inc();
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bio_put(bio);
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/*
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* Wait to complete the task until the last bio as completed.
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*/
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if (!atomic_dec_and_test(&ibr->ib_bio_cnt))
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return;
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ibr->ib_bio = NULL;
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transport_complete_task(task, 0);
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return;
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}
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pr_debug("done[%p] bio: %p task_lba: %llu bio_lba: %llu err=%d\n",
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task, bio, task->task_lba, (unsigned long long)bio->bi_sector, err);
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/*
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* bio_put() will call iblock_bio_destructor() to release the bio back
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* to ibr->ib_bio_set.
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*/
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bio_put(bio);
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/*
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* Wait to complete the task until the last bio as completed.
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*/
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if (!atomic_dec_and_test(&ibr->ib_bio_cnt))
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return;
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/*
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* Return GOOD status for task if zero ib_bio_err_cnt exists.
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*/
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ibr->ib_bio = NULL;
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transport_complete_task(task, (!atomic_read(&ibr->ib_bio_err_cnt)));
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pr_debug("done[%p] bio: %p task_lba: %llu bio_lba: %llu err=%d\n",
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task, bio, task->task_lba,
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(unsigned long long)bio->bi_sector, err);
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transport_complete_task(task, !atomic_read(&ibr->ib_bio_err_cnt));
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}
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static struct se_subsystem_api iblock_template = {
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.name = "iblock",
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.owner = THIS_MODULE,
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.transport_type = TRANSPORT_PLUGIN_VHBA_PDEV,
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.map_data_SG = iblock_map_data_SG,
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.attach_hba = iblock_attach_hba,
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.detach_hba = iblock_detach_hba,
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.allocate_virtdevice = iblock_allocate_virtdevice,
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@ -11,7 +11,6 @@ struct iblock_req {
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unsigned char ib_scsi_cdb[TCM_MAX_COMMAND_SIZE];
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atomic_t ib_bio_cnt;
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atomic_t ib_bio_err_cnt;
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struct bio *ib_bio;
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} ____cacheline_aligned;
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#define IBDF_HAS_UDEV_PATH 0x01
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