Re: [PATCH 7/7] sd: use ZERO_PAGE for WRITE_SAME payloads
From: Bart Van Assche <hidden>
Date: 2017-03-27 23:40:12
Also in:
linux-ide, linux-scsi
On Mon, 2017-03-20 at 16:43 -0400, Christoph Hellwig wrote:
quoted hunk ↗ jump to hunk
We're never touching the contents of the page, so save a memory allocation for these cases. =20 Signed-off-by: Christoph Hellwig <hch@lst.de> --- drivers/scsi/sd.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) =20diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index c18fe9ff1f8f..af632e350ab4 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c@@ -756,7 +756,7 @@ static int sd_setup_write_same16_cmnd(struct scsi_cmn=
d *cmd)
quoted hunk ↗ jump to hunk
u32 nr_sectors =3D blk_rq_sectors(rq) >> (ilog2(sdp->sector_size) - 9); u32 data_len =3D sdp->sector_size; =20 - rq->special_vec.bv_page =3D alloc_page(GFP_ATOMIC | __GFP_ZERO); + rq->special_vec.bv_page =3D ZERO_PAGE(0); if (!rq->special_vec.bv_page) return BLKPREP_DEFER; rq->special_vec.bv_offset =3D 0;@@ -785,7 +785,7 @@ static int sd_setup_write_same10_cmnd(struct scsi_cmn=
d *cmd, bool unmap)
quoted hunk ↗ jump to hunk
u32 nr_sectors =3D blk_rq_sectors(rq) >> (ilog2(sdp->sector_size) - 9); u32 data_len =3D sdp->sector_size; =20 - rq->special_vec.bv_page =3D alloc_page(GFP_ATOMIC | __GFP_ZERO); + rq->special_vec.bv_page =3D ZERO_PAGE(0); if (!rq->special_vec.bv_page) return BLKPREP_DEFER; rq->special_vec.bv_offset =3D 0;@@ -1256,7 +1256,8 @@ static void sd_uninit_command(struct scsi_cmnd *SCp=
nt)
{
struct request *rq =3D SCpnt->request;
=20
- if (rq->rq_flags & RQF_SPECIAL_PAYLOAD)
+ if ((rq->rq_flags & RQF_SPECIAL_PAYLOAD) &&
+ rq->special_vec.bv_page !=3D ZERO_PAGE(0))
__free_page(rq->special_vec.bv_page);
=20
if (SCpnt->cmnd !=3D scsi_req(rq)->cmd) {Reviewed-by: Bart Van Assche <redacted>