From 66ac0280197981f88774e74b60c8e5f9f07c1dba Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Fri, 18 Jun 2010 16:59:42 +0200 Subject: block: don't allocate a payload for discard request Allocating a fixed payload for discard requests always was a horrible hack, and it's not coming to byte us when adding support for discard in DM/MD. So change the code to leave the allocation of a payload to the lowlevel driver. Unfortunately that means we'll need another hack, which allows us to update the various block layer length fields indicating that we have a payload. Instead of hiding this in sd.c, which we already partially do for UNMAP support add a documented helper in the core block layer for it. Signed-off-by: Christoph Hellwig Acked-by: Mike Snitzer Signed-off-by: Jens Axboe --- drivers/scsi/sd.c | 52 ++++++++++++++++++++++++++++++++++------------------ 1 file changed, 34 insertions(+), 18 deletions(-) (limited to 'drivers/scsi/sd.c') diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index a3fdf4dc59d..86da819c70e 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -411,22 +411,25 @@ static void sd_prot_op(struct scsi_cmnd *scmd, unsigned int dif) } /** - * sd_prepare_discard - unmap blocks on thinly provisioned device + * scsi_setup_discard_cmnd - unmap blocks on thinly provisioned device + * @sdp: scsi device to operate one * @rq: Request to prepare * * Will issue either UNMAP or WRITE SAME(16) depending on preference * indicated by target device. **/ -static int sd_prepare_discard(struct request *rq) +static int scsi_setup_discard_cmnd(struct scsi_device *sdp, struct request *rq) { struct scsi_disk *sdkp = scsi_disk(rq->rq_disk); struct bio *bio = rq->bio; sector_t sector = bio->bi_sector; - unsigned int num = bio_sectors(bio); + unsigned int nr_sectors = bio_sectors(bio); + unsigned int len; + struct page *page; if (sdkp->device->sector_size == 4096) { sector >>= 3; - num >>= 3; + nr_sectors >>= 3; } rq->cmd_type = REQ_TYPE_BLOCK_PC; @@ -434,31 +437,35 @@ static int sd_prepare_discard(struct request *rq) memset(rq->cmd, 0, rq->cmd_len); + page = alloc_page(GFP_ATOMIC | __GFP_ZERO); + if (!page) + return BLKPREP_DEFER; + if (sdkp->unmap) { - char *buf = kmap_atomic(bio_page(bio), KM_USER0); + char *buf = page_address(page); + rq->cmd_len = 10; rq->cmd[0] = UNMAP; rq->cmd[8] = 24; - rq->cmd_len = 10; - - /* Ensure that data length matches payload */ - rq->__data_len = bio->bi_size = bio->bi_io_vec->bv_len = 24; put_unaligned_be16(6 + 16, &buf[0]); put_unaligned_be16(16, &buf[2]); put_unaligned_be64(sector, &buf[8]); - put_unaligned_be32(num, &buf[16]); + put_unaligned_be32(nr_sectors, &buf[16]); - kunmap_atomic(buf, KM_USER0); + len = 24; } else { + rq->cmd_len = 16; rq->cmd[0] = WRITE_SAME_16; rq->cmd[1] = 0x8; /* UNMAP */ put_unaligned_be64(sector, &rq->cmd[2]); - put_unaligned_be32(num, &rq->cmd[10]); - rq->cmd_len = 16; + put_unaligned_be32(nr_sectors, &rq->cmd[10]); + + len = sdkp->device->sector_size; } - return BLKPREP_OK; + blk_add_request_payload(rq, page, len); + return scsi_setup_blk_pc_cmnd(sdp, rq); } /** @@ -485,10 +492,10 @@ static int sd_prep_fn(struct request_queue *q, struct request *rq) * Discard request come in as REQ_TYPE_FS but we turn them into * block PC requests to make life easier. */ - if (rq->cmd_flags & REQ_DISCARD) - ret = sd_prepare_discard(rq); - - if (rq->cmd_type == REQ_TYPE_BLOCK_PC) { + if (rq->cmd_flags & REQ_DISCARD) { + ret = scsi_setup_discard_cmnd(sdp, rq); + goto out; + } else if (rq->cmd_type == REQ_TYPE_BLOCK_PC) { ret = scsi_setup_blk_pc_cmnd(sdp, rq); goto out; } else if (rq->cmd_type != REQ_TYPE_FS) { @@ -1163,6 +1170,15 @@ static int sd_done(struct scsi_cmnd *SCpnt) int sense_valid = 0; int sense_deferred = 0; + /* + * If this is a discard request that originated from the kernel + * we need to free our payload here. Note that we need to check + * the request flag as the normal payload rules apply for + * pass-through UNMAP / WRITE SAME requests. + */ + if (SCpnt->request->cmd_flags & REQ_DISCARD) + __free_page(bio_page(SCpnt->request->bio)); + if (result) { sense_valid = scsi_command_normalize_sense(SCpnt, &sshdr); if (sense_valid) -- cgit v1.2.3