diff options
| author | Yu Kuai <yukuai3@huawei.com> | 2022-11-01 09:31:24 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-11-03 23:59:20 +0900 |
| commit | aad798a0b39c636d62d27e03fb399b1f0f727e0c (patch) | |
| tree | e1284a1303c098c4f45b7d4ca839f189125ffbb1 /drivers | |
| parent | 52c2329147cf5d956dcaa3a91c886c550e7bdd39 (diff) | |
scsi: sd: Revert "scsi: sd: Remove a local variable"
This reverts commit 84f7a9de0602704bbec774a6c7f7c8c4994bee9c.
Because it introduces a problem that rq->__data_len is set to the wrong
value.
before the patch:
1) nr_bytes = rq->__data_len
2) rq->__data_len = sdp->sector_size
3) scsi_init_io()
4) rq->__data_len = nr_bytes
after the patch:
1) rq->__data_len = sdp->sector_size
2) scsi_init_io()
3) rq->__data_len = rq->__data_len -> __data_len is wrong
It will cause that io can only complete one segment each time, and the io
will requeue in scsi_io_completion_action(), which will cause severe
performance degradation.
Scsi write same is removed in commit e383e16e84e9 ("scsi: sd: Remove
WRITE_SAME support") from mainline, hence this patch is only needed for
stable kernels.
Fixes: 84f7a9de0602 ("scsi: sd: Remove a local variable")
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/scsi/sd.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index de6640ad1943..1e887c11e83d 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -1072,6 +1072,7 @@ static blk_status_t sd_setup_write_same_cmnd(struct scsi_cmnd *cmd) struct bio *bio = rq->bio; u64 lba = sectors_to_logical(sdp, blk_rq_pos(rq)); u32 nr_blocks = sectors_to_logical(sdp, blk_rq_sectors(rq)); + unsigned int nr_bytes = blk_rq_bytes(rq); blk_status_t ret; if (sdkp->device->no_write_same) @@ -1108,7 +1109,7 @@ static blk_status_t sd_setup_write_same_cmnd(struct scsi_cmnd *cmd) */ rq->__data_len = sdp->sector_size; ret = scsi_alloc_sgtables(cmd); - rq->__data_len = blk_rq_bytes(rq); + rq->__data_len = nr_bytes; return ret; } |