For failover handling, we must resubmit each bio. However, unlike NVMe, for SCSI there is no guarantee that any bio submitted is either all or none completed.
As such, for SCSI, for failover handling we will take the approach to just re-submit the original bio. For this clone and submit each bio. Signed-off-by: John Garry <[email protected]> --- drivers/scsi/scsi_multipath.c | 51 ++++++++++++++++++++++++++++++++++- include/scsi/scsi_multipath.h | 1 + 2 files changed, 51 insertions(+), 1 deletion(-) diff --git a/drivers/scsi/scsi_multipath.c b/drivers/scsi/scsi_multipath.c index 4b7984e7e74ba..d79a92ec0cf6c 100644 --- a/drivers/scsi/scsi_multipath.c +++ b/drivers/scsi/scsi_multipath.c @@ -89,6 +89,14 @@ module_param_call(iopolicy, scsi_set_iopolicy, scsi_get_iopolicy, MODULE_PARM_DESC(iopolicy, "Default multipath I/O policy; 'numa' (default), 'round-robin' or 'queue-depth'"); +struct scsi_mpath_clone_bio { + struct bio *master_bio; + struct bio clone; +}; + +#define scsi_mpath_to_master_bio(clone) \ + container_of(clone, struct scsi_mpath_clone_bio, clone) + static int scsi_mpath_unique_lun_id(struct scsi_device *sdev) { struct scsi_mpath_device *scsi_mpath_dev = sdev->scsi_mpath_dev; @@ -116,6 +124,7 @@ static void scsi_mpath_head_release(struct device *dev) struct mpath_head *mpath_head = scsi_mpath_head->mpath_head; scsi_mpath_delete_head(scsi_mpath_head); + bioset_exit(&scsi_mpath_head->bio_pool); ida_free(&scsi_multipath_dev_ida, scsi_mpath_head->index); mpath_put_head(mpath_head); kfree(scsi_mpath_head); @@ -260,6 +269,39 @@ static int scsi_multipath_sdev_init(struct scsi_device *sdev) return 0; } +static void scsi_mpath_clone_end_io(struct bio *clone) +{ + struct scsi_mpath_clone_bio *scsi_mpath_clone_bio = + scsi_mpath_to_master_bio(clone); + struct bio *master_bio = scsi_mpath_clone_bio->master_bio; + + master_bio->bi_status = clone->bi_status; + bio_put(clone); + bio_endio(master_bio); +} + +static struct bio *scsi_mpath_clone_bio(struct bio *bio) +{ + struct mpath_disk *mpath_disk = bio->bi_bdev->bd_disk->private_data; + struct mpath_head *mpath_head = mpath_disk->mpath_head; + struct scsi_mpath_clone_bio *scsi_mpath_clone_bio; + struct scsi_mpath_head *scsi_mpath_head = mpath_head->drvdata; + struct bio *clone; + + clone = bio_alloc_clone(bio->bi_bdev, bio, GFP_NOWAIT, + &scsi_mpath_head->bio_pool); + if (!clone) + return NULL; + + clone->bi_end_io = scsi_mpath_clone_end_io; + + scsi_mpath_clone_bio = container_of(clone, + struct scsi_mpath_clone_bio, clone); + scsi_mpath_clone_bio->master_bio = bio; + + return clone; +} + static enum mpath_iopolicy_e scsi_mpath_get_iopolicy(struct mpath_head *mpath_head) { struct scsi_mpath_head *scsi_mpath_head = mpath_head->drvdata; @@ -269,6 +311,7 @@ static enum mpath_iopolicy_e scsi_mpath_get_iopolicy(struct mpath_head *mpath_he struct mpath_head_template smpdt_pr = { .get_iopolicy = scsi_mpath_get_iopolicy, + .clone_bio = scsi_mpath_clone_bio, }; static struct scsi_mpath_head *scsi_mpath_alloc_head(void) @@ -283,9 +326,13 @@ static struct scsi_mpath_head *scsi_mpath_alloc_head(void) ida_init(&scsi_mpath_head->ida); mutex_init(&scsi_mpath_head->lock); + if (bioset_init(&scsi_mpath_head->bio_pool, SCSI_MAX_QUEUE_DEPTH, + offsetof(struct scsi_mpath_clone_bio, clone), + BIOSET_NEED_BVECS|BIOSET_PERCPU_CACHE)) + goto out_free; scsi_mpath_head->mpath_head = mpath_alloc_head(); if (IS_ERR(scsi_mpath_head->mpath_head)) - goto out_free; + goto out_bioset_exit; scsi_mpath_head->mpath_head->mpdt = &smpdt_pr; scsi_mpath_head->mpath_head->drvdata = scsi_mpath_head; @@ -307,6 +354,8 @@ static struct scsi_mpath_head *scsi_mpath_alloc_head(void) ida_free(&scsi_multipath_dev_ida, scsi_mpath_head->index); out_put_head: mpath_put_head(scsi_mpath_head->mpath_head); +out_bioset_exit: + bioset_exit(&scsi_mpath_head->bio_pool); out_free: kfree(scsi_mpath_head); return NULL; diff --git a/include/scsi/scsi_multipath.h b/include/scsi/scsi_multipath.h index 8dbe1c3784d2c..bd99ea017379d 100644 --- a/include/scsi/scsi_multipath.h +++ b/include/scsi/scsi_multipath.h @@ -26,6 +26,7 @@ struct scsi_mpath_head { struct ida ida; struct mutex lock; struct mpath_iopolicy iopolicy; + struct bio_set bio_pool; struct mpath_head *mpath_head; struct device dev; int index; -- 2.43.5
