From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Bart Van Assche To: "hch@lst.de" , "tj@kernel.org" , "martin.petersen@oracle.com" , "axboe@kernel.dk" CC: "linux-scsi@vger.kernel.org" , "linux-block@vger.kernel.org" , "linux-ide@vger.kernel.org" Subject: Re: [PATCH 7/7] sd: use ZERO_PAGE for WRITE_SAME payloads Date: Mon, 27 Mar 2017 23:40:12 +0000 Message-ID: <1490657999.7897.21.camel@sandisk.com> References: <20170320204319.12628-1-hch@lst.de> <20170320204319.12628-8-hch@lst.de> In-Reply-To: <20170320204319.12628-8-hch@lst.de> Content-Type: text/plain; charset="iso-8859-1" MIME-Version: 1.0 Return-Path: Bart.VanAssche@sandisk.com List-ID: On Mon, 2017-03-20 at 16:43 -0400, Christoph Hellwig wrote: > We're never touching the contents of the page, so save a memory > allocation for these cases. >=20 > Signed-off-by: Christoph Hellwig > --- > drivers/scsi/sd.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) >=20 > diff --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) > 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) > 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