raid5: set bio bi_vcnt 0 for discard request

PATCH In review Shaohua Li 3 participants 3 messages Oct 19, 2013 – Oct 24, 2013 MD RAID

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Shaohua Li

author

2013-10-19 06:50 UTC #0 lore raw

PATCH 1/2 raid5: set bio bi_vcnt 0 for discard request

SCSI layer will add new payload for discard request. If two bios are merged to one, the second bio has bi_vcnt 1 which is set in raid5. This will confuse SCSI and cause oops.

Suite for backport to 3.7+

Reported-by Jes Sorensen <[email protected]>

Signed-off-by Shaohua Li <[email protected]>

---
 drivers/md/raid5.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)

drivers/md/raid5.c +12 -0

Index: linux/drivers/md/raid5.c
===================================================================
@@ -877,6 +877,12 @@ static void ops_run_io(struct stripe_hea
 			bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
 			bi->bi_io_vec[0].bv_offset = 0;
 			bi->bi_size = STRIPE_SIZE;
+			/*
+			 * If this is discard request, set bi_vcnt 0. We don't
+			 * want to confuse SCSI because SCSI will replace payload
+			 */
+			if (rw & REQ_DISCARD)
+				bi->bi_vcnt = 0;
 			if (rrdev)
 				set_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags);

@@ -915,6 +921,12 @@ static void ops_run_io(struct stripe_hea
 			rbi->bi_io_vec[0].bv_len = STRIPE_SIZE;
 			rbi->bi_io_vec[0].bv_offset = 0;
 			rbi->bi_size = STRIPE_SIZE;
+			/*
+			 * If this is discard request, set bi_vcnt 0. We don't
+			 * want to confuse SCSI because SCSI will replace payload
+			 */
+			if (rw & REQ_DISCARD)
+				rbi->bi_vcnt = 0;
 			if (conf->mddev->gendisk)
 				trace_block_bio_remap(bdev_get_queue(rbi->bi_bdev),
 						      rbi, disk_devt(conf->mddev->gendisk),

Martin K. Petersen

Acked-by on v1 1/2

2013-10-23 08:07 UTC #1 lore raw

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"Shaohua" == Shaohua Li <[email protected]> writes:

Shaohua> SCSI layer will add new payload for discard request. If two Shaohua> bios are merged to one, the second bio has bi_vcnt 1 which is Shaohua> set in raid5. This will confuse SCSI and cause oops.

A discard bio does not have a payload prior to the SCSI command being prepared so vcnt should indeed be 0.

Acked-by Martin K. Petersen <[email protected]>

Signature · 1 line

Martin K. Petersen	Oracle Linux Engineering

NeilBrown

2013-10-24 01:58 UTC #2 lore raw

Quoted 11 lines · On Wed, 23 Oct 2013 04:07:19 -0400 "Martin K. Petersen"…

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"Shaohua" == Shaohua Li <[email protected]> writes:
Shaohua> SCSI layer will add new payload for discard request. If two Shaohua> bios are merged to one, the second bio has bi_vcnt 1 which is Shaohua> set in raid5. This will confuse SCSI and cause oops.
A discard bio does not have a payload prior to the SCSI command being prepared so vcnt should indeed be 0.
Acked-by Martin K. Petersen <[email protected]>

Thanks Martin. I'll be sending this to Linus shortly.

NeilBrown