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Commit 0fb5b1fb authored by Martin K. Petersen's avatar Martin K. Petersen
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block/sd: Return -EREMOTEIO when WRITE SAME and DISCARD are disabled 



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: default avatarYiwen Jiang <jiangyiwen@huawei.com>
Suggested-by: default avatarMike Snitzer <snitzer@redhat.com>
Reviewed-by: default avatarHannes Reinicke <hare@suse.de>
Reviewed-by: default avatarEwan Milne <emilne@redhat.com>
Reviewed-by: default avatarYiwen Jiang <jiangyiwen@huawei.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent 82c43310

block/blk-core.c

+4 −2
Original line number Diff line number Diff line
@@ -2447,14 +2447,16 @@ 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;

drivers/scsi/sd.c

+2 −2
Original line number Diff line number Diff line
@@ -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);

include/linux/blkdev.h

+6 −3
Original line number Diff line number Diff line
@@ -681,9 +681,12 @@ 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_DEFER,		/* leave on queue */

	BLKPREP_INVALID,	/* invalid command, kill, return -EREMOTEIO */

};



extern unsigned long blk_max_low_pfn, blk_max_pfn;