diff options
| author | Yu Kuai <yukuai3@huawei.com> | 2022-11-01 04:31:24 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-11-03 17:57:54 +0300 |
| commit | d523384766fd5492ab77f49b5e646fa756e5ab4f (patch) | |
| tree | f05729db626789bc9a9760b6c8558952e4bd5e0d | |
| parent | 52a43b82006dc88f996bd06da5a3fcfef85220c8 (diff) | |
| download | linux-d523384766fd5492ab77f49b5e646fa756e5ab4f.tar.xz | |
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>
| -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 bd068d3bb455..58f66176bcb2 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -1074,6 +1074,7 @@ 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) @@ -1110,7 +1111,7 @@ 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; } |