For a scmd which suffers failover, requeue the master bio of each bio attached to its request.
A handler is added in the scsi_driver structure to lookup a mpath_disk from a request. This is needed because the scsi_disk structure will manage the mpath_disk, and the code core has no method to look this up from the scsi_scmnd. Failover occurs when the scsi_cmnd has failed and it is discovered that the original scsi_device has transport down. Signed-off-by: John Garry <[email protected]> --- drivers/scsi/scsi_error.c | 12 ++++++ drivers/scsi/scsi_lib.c | 9 +++- drivers/scsi/scsi_multipath.c | 80 +++++++++++++++++++++++++++++++++++ include/scsi/scsi.h | 1 + include/scsi/scsi_driver.h | 3 ++ include/scsi/scsi_multipath.h | 14 ++++++ 6 files changed, 118 insertions(+), 1 deletion(-) diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c index f869108fd9693..0fd1b46764c3f 100644 --- a/drivers/scsi/scsi_error.c +++ b/drivers/scsi/scsi_error.c @@ -40,6 +40,7 @@ #include <scsi/scsi_ioctl.h> #include <scsi/scsi_dh.h> #include <scsi/scsi_devinfo.h> +#include <scsi/scsi_multipath.h> #include <scsi/sg.h> #include "scsi_priv.h" @@ -1901,12 +1902,16 @@ bool scsi_noretry_cmd(struct scsi_cmnd *scmd) enum scsi_disposition scsi_decide_disposition(struct scsi_cmnd *scmd) { enum scsi_disposition rtn; + struct request *req = scsi_cmd_to_rq(scmd); /* * if the device is offline, then we clearly just pass the result back * up to the top level. */ if (!scsi_device_online(scmd->device)) { + if (scsi_is_mpath_request(req)) + return scsi_mpath_failover_disposition(scmd); + SCSI_LOG_ERROR_RECOVERY(5, scmd_printk(KERN_INFO, scmd, "%s: device offline - report as SUCCESS\n", __func__)); return SUCCESS; @@ -2070,6 +2075,13 @@ enum scsi_disposition scsi_decide_disposition(struct scsi_cmnd *scmd) maybe_retry: + /* + * For SCSI Multipath check if there are path errors to + * trigger failover to available path + */ + if (scsi_is_mpath_request(req)) + return scsi_mpath_failover_disposition(scmd); + /* we requeue for retry because the error was retryable, and * the request was not marked fast fail. Note that above, * even if the request is marked fast fail, we still requeue diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index ab224cd61f3ae..7ed0defc8161e 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -1550,7 +1550,7 @@ static void scsi_complete(struct request *rq) atomic_inc(&cmd->device->ioerr_cnt); disposition = scsi_decide_disposition(cmd); - if (disposition != SUCCESS && scsi_cmd_runtime_exceeced(cmd)) + if (disposition != SUCCESS && disposition != FAILOVER && scsi_cmd_runtime_exceeced(cmd)) disposition = SUCCESS; scsi_log_completion(cmd, disposition); @@ -1565,6 +1565,9 @@ static void scsi_complete(struct request *rq) case ADD_TO_MLQUEUE: scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY); break; + case FAILOVER: + scsi_mpath_failover_req(rq); + break; default: scsi_eh_scmd_add(cmd); break; @@ -1935,6 +1938,10 @@ static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx, if (req->rq_flags & RQF_DONTPREP) scsi_mq_uninit_cmd(cmd); scsi_run_queue_async(sdev); + if (!scsi_device_online(sdev) && scsi_is_mpath_request(req)) { + scsi_mpath_failover_req(req); + return 0; + } break; } return ret; diff --git a/drivers/scsi/scsi_multipath.c b/drivers/scsi/scsi_multipath.c index c3e0f792e921f..16b1f84fc552c 100644 --- a/drivers/scsi/scsi_multipath.c +++ b/drivers/scsi/scsi_multipath.c @@ -518,6 +518,86 @@ void scsi_mpath_put_head(struct scsi_mpath_head *scsi_mpath_head) } EXPORT_SYMBOL_GPL(scsi_mpath_put_head); +bool scsi_is_mpath_request(struct request *req) +{ + return is_mpath_request(req); +} +EXPORT_SYMBOL_GPL(scsi_is_mpath_request); + +static inline void bio_list_add_clone_master(struct bio_list *bl, + struct bio *clone) +{ + struct scsi_mpath_clone_bio *scsi_mpath_clone_bio; + struct bio *master_bio; + + if (clone->bi_next) + bio_list_add_clone_master(bl, clone->bi_next); + + scsi_mpath_clone_bio = scsi_mpath_to_master_bio(clone); + master_bio = scsi_mpath_clone_bio->master_bio; + + if (bl->tail) + bl->tail->bi_next = master_bio; + else + bl->head = master_bio; + + bl->tail = master_bio; + + bio_put(clone); +} + +void scsi_mpath_failover_req(struct request *req) +{ + struct scsi_cmnd *scmd = blk_mq_rq_to_pdu(req); + struct scsi_device *sdev = scmd->device; + struct scsi_driver *drv = to_scsi_driver(sdev->sdev_gendev.driver); + struct mpath_disk *mpath_disk = drv->to_mpath_disk(req); + struct scsi_mpath_device *scsi_mpath_dev = sdev->scsi_mpath_dev; + struct mpath_head *mpath_head = mpath_disk->mpath_head; + unsigned long flags; + + scsi_mpath_dev_clear_path(scsi_mpath_dev); + + spin_lock_irqsave(&mpath_head->requeue_lock, flags); + bio_list_add_clone_master(&mpath_head->requeue_list, req->bio); + spin_unlock_irqrestore(&mpath_head->requeue_lock, flags); + req->bio = NULL; + req->biotail = NULL; + req->__data_len = 0; + + /* End old request with clone detached */ + scmd->result = 0; + blk_mq_end_request(req, 0); + + kblockd_schedule_work(&mpath_head->requeue_work); +} + +static inline bool scsi_is_mpath_error(struct scsi_cmnd *scmd) +{ + struct scsi_device *sdev = scmd->device; + + if (sdev->sdev_state == SDEV_TRANSPORT_OFFLINE) + return true; + return false; +} + +int scsi_mpath_failover_disposition(struct scsi_cmnd *scmd) +{ + struct request *req = scsi_cmd_to_rq(scmd); + + if (is_mpath_request(req)) { + if (scsi_is_mpath_error(scmd) || + blk_queue_dying(req->q)) + return FAILOVER; + return NEEDS_RETRY; + } else { + if (blk_queue_dying(req->q)) + return SUCCESS; + } + + return SUCCESS; +} + int __init scsi_multipath_init(void) { return class_register(&scsi_mpath_device_class); diff --git a/include/scsi/scsi.h b/include/scsi/scsi.h index 96b3503666703..544153a01b3fd 100644 --- a/include/scsi/scsi.h +++ b/include/scsi/scsi.h @@ -103,6 +103,7 @@ enum scsi_disposition { TIMEOUT_ERROR = 0x2007, SCSI_RETURN_NOT_HANDLED = 0x2008, FAST_IO_FAIL = 0x2009, + FAILOVER = 0x2010, }; /* diff --git a/include/scsi/scsi_driver.h b/include/scsi/scsi_driver.h index c0e89996bdb3f..85e792dc4db50 100644 --- a/include/scsi/scsi_driver.h +++ b/include/scsi/scsi_driver.h @@ -19,6 +19,9 @@ struct scsi_driver { int (*done)(struct scsi_cmnd *); int (*eh_action)(struct scsi_cmnd *, int); void (*eh_reset)(struct scsi_cmnd *); + #ifdef CONFIG_SCSI_MULTIPATH + struct mpath_disk *(*to_mpath_disk)(struct request *); + #endif }; #define to_scsi_driver(drv) \ container_of((drv), struct scsi_driver, gendrv) diff --git a/include/scsi/scsi_multipath.h b/include/scsi/scsi_multipath.h index 79e6860243e74..07db217edb085 100644 --- a/include/scsi/scsi_multipath.h +++ b/include/scsi/scsi_multipath.h @@ -43,6 +43,9 @@ struct scsi_mpath_device { #define to_scsi_mpath_device(d) \ container_of(d, struct scsi_mpath_device, mpath_device) +void scsi_mpath_failover_req(struct request *); +int scsi_mpath_failover_disposition(struct scsi_cmnd *); +bool scsi_is_mpath_request(struct request *req); int scsi_mpath_dev_alloc(struct scsi_device *sdev); void scsi_mpath_dev_release(struct scsi_device *sdev); int scsi_multipath_init(void); @@ -60,6 +63,17 @@ struct scsi_mpath_head { struct scsi_mpath_device { }; +static inline void scsi_mpath_failover_req(struct request *) +{ +} +static inline int scsi_mpath_failover_disposition(struct scsi_cmnd *) +{ + return 0; +} +static inline bool scsi_is_mpath_request(struct request *req) +{ + return false; +} static inline int scsi_mpath_dev_alloc(struct scsi_device *sdev) { return 0; -- 2.43.5
