When a storage device rejects a WRITE SAME command we will disable write same functionality for the device and return -EREMOTEIO to the block layer. -EREMOTEIO will in turn prevent DM from retrying the I/O and/or failing the path.
Yiwen Jiang discovered a small race where WRITE SAME requests issued simultaneously would cause -EIO to be returned. This happened because any requests being prepared after WRITE SAME had been disabled for the device caused us to return BLKPREP_KILL. The latter caused the block layer to return -EIO upon completion. To overcome this we introduce BLKPREP_INVALID which indicates that this is an invalid request for the device. blk_peek_request() is modified to return -EREMOTEIO in that case. Reported-by: Yiwen Jiang <[email protected]> Suggested-by: Mike Snitzer <[email protected]> Signed-off-by: Martin K. Petersen <[email protected]> --- I contemplated making blk_peek_request() use rq->errors to decide what to return up the stack. However, I cringed at mixing errnos and SCSI midlayer status information in the same location. --- block/blk-core.c | 6 ++++-- drivers/scsi/sd.c | 4 ++-- include/linux/blkdev.h | 9 ++++++--- 3 files changed, 12 insertions(+), 7 deletions(-) diff --git a/block/blk-core.c b/block/blk-core.c index 33e2f62d5062..ee833af2f892 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -2446,14 +2446,16 @@ struct request *blk_peek_request(struct request_queue *q) rq = NULL; break; - } else if (ret == BLKPREP_KILL) { + } else if (ret == BLKPREP_KILL || ret == BLKPREP_INVALID) { + int err = ret == BLKPREP_INVALID ? -EREMOTEIO : -EIO; + rq->cmd_flags |= REQ_QUIET; /* * Mark this request as started so we don't trigger * any debug logic in the end I/O path. */ blk_start_request(rq); - __blk_end_request_all(rq, -EIO); + __blk_end_request_all(rq, err); } else { printk(KERN_ERR "%s: bad return=%d\n", __func__, ret); break; diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index ec163d08f6c3..6e841c6da632 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -761,7 +761,7 @@ static int sd_setup_discard_cmnd(struct scsi_cmnd *cmd) break; default: - ret = BLKPREP_KILL; + ret = BLKPREP_INVALID; goto out; } @@ -839,7 +839,7 @@ static int sd_setup_write_same_cmnd(struct scsi_cmnd *cmd) int ret; if (sdkp->device->no_write_same) - return BLKPREP_KILL; + return BLKPREP_INVALID; BUG_ON(bio_offset(bio) || bio_iovec(bio).bv_len != sdp->sector_size); diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index c70e3588a48c..e990d181625a 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -680,9 +680,12 @@ static inline bool blk_write_same_mergeable(struct bio *a, struct bio *b) /* * q->prep_rq_fn return values */ -#define BLKPREP_OK 0 /* serve it */ -#define BLKPREP_KILL 1 /* fatal error, kill */ -#define BLKPREP_DEFER 2 /* leave on queue */ +enum { + BLKPREP_OK, /* serve it */ + BLKPREP_KILL, /* fatal error, kill, return -EIO */ + BLKPREP_INVALID, /* invalid command, kill, return -EREMOTEIO */ + BLKPREP_DEFER, /* leave on queue */ +}; extern unsigned long blk_max_low_pfn, blk_max_pfn; -- 2.7.0 -- 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
