From: Nicholas Bellinger <[email protected]> This patch updates target/iblock backend driver code to check for bio completion status of -EAGAIN / -ENOMEM provided by raw block drivers and scsi devices, in order to generate the following SCSI status to initiators:
- SAM_STAT_BUSY - SAM_STAT_TASK_SET_FULL Note these two SAM status codes are useful to signal to Linux SCSI host side that se_cmd should be retried again, or with TASK_SET_FULL case to attempt to lower our internal host LLD queue_depth and scsi_cmnd retry. It also updates target_complete_cmd() to parse status when signalling success to target_completion_wq. Reviewed-by: Hannes Reinecke <[email protected]> Cc: Christoph Hellwig <[email protected]> Cc: Hannes Reinecke <[email protected]> Cc: Sagi Grimberg <[email protected]> Cc: Andy Grover <[email protected]> Cc: Mike Christie <[email protected]> Signed-off-by: Nicholas Bellinger <[email protected]> --- drivers/target/target_core_iblock.c | 38 +++++++++++++++++++++++++++------- drivers/target/target_core_iblock.h | 1 + drivers/target/target_core_transport.c | 13 ++++++++++-- 3 files changed, 43 insertions(+), 9 deletions(-) diff --git a/drivers/target/target_core_iblock.c b/drivers/target/target_core_iblock.c index 026a758..ce754f1 100644 --- a/drivers/target/target_core_iblock.c +++ b/drivers/target/target_core_iblock.c @@ -282,11 +282,28 @@ static void iblock_complete_cmd(struct se_cmd *cmd) if (!atomic_dec_and_test(&ibr->pending)) return; - - if (atomic_read(&ibr->ib_bio_err_cnt)) - status = SAM_STAT_CHECK_CONDITION; - else + /* + * Propigate use these two bio completion values from raw block + * drivers to signal up BUSY and TASK_SET_FULL status to the + * host side initiator. The latter for Linux/iSCSI initiators + * means the Linux/SCSI LLD will begin to reduce it's internal + * per session queue_depth. + */ + if (atomic_read(&ibr->ib_bio_err_cnt)) { + switch (ibr->ib_bio_retry) { + case -EAGAIN: + status = SAM_STAT_BUSY; + break; + case -ENOMEM: + status = SAM_STAT_TASK_SET_FULL; + break; + default: + status = SAM_STAT_CHECK_CONDITION; + break; + } + } else { status = SAM_STAT_GOOD; + } target_complete_cmd(cmd, status); kfree(ibr); @@ -298,7 +315,15 @@ static void iblock_bio_done(struct bio *bio) struct iblock_req *ibr = cmd->priv; if (bio->bi_error) { - pr_err("bio error: %p, err: %d\n", bio, bio->bi_error); + pr_debug_ratelimited("test_bit(BIO_UPTODATE) failed for bio: %p," + " err: %d\n", bio, bio->bi_error); + /* + * Save the retryable status provided and translate into + * SAM status in iblock_complete_cmd(). + */ + if (bio->bi_error == -EAGAIN || bio->bi_error == -ENOMEM) { + ibr->ib_bio_retry = bio->bi_error; + } /* * Bump the ib_bio_err_cnt and release bio. */ @@ -677,8 +702,7 @@ iblock_execute_rw(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents, struct scatterlist *sg; u32 sg_num = sgl_nents; unsigned bio_cnt; - int rw = 0; - int i; + int i, rw = 0; if (data_direction == DMA_TO_DEVICE) { struct iblock_dev *ib_dev = IBLOCK_DEV(dev); diff --git a/drivers/target/target_core_iblock.h b/drivers/target/target_core_iblock.h index 01c2afd..ff3cfdd 100644 --- a/drivers/target/target_core_iblock.h +++ b/drivers/target/target_core_iblock.h @@ -9,6 +9,7 @@ struct iblock_req { atomic_t pending; atomic_t ib_bio_err_cnt; + int ib_bio_retry; } ____cacheline_aligned; #define IBDF_HAS_UDEV_PATH 0x01 diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c index 784dd22..df01997 100644 --- a/drivers/target/target_core_transport.c +++ b/drivers/target/target_core_transport.c @@ -731,11 +731,20 @@ static unsigned char *transport_get_sense_buffer(struct se_cmd *cmd) void target_complete_cmd(struct se_cmd *cmd, u8 scsi_status) { struct se_device *dev = cmd->se_dev; - int success = scsi_status == GOOD; + int success; unsigned long flags; cmd->scsi_status = scsi_status; - + switch (cmd->scsi_status) { + case SAM_STAT_GOOD: + case SAM_STAT_BUSY: + case SAM_STAT_TASK_SET_FULL: + success = 1; + break; + default: + success = 0; + break; + } spin_lock_irqsave(&cmd->t_state_lock, flags); cmd->transport_state &= ~CMD_T_BUSY; -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
