[SCSI] sd: Permit merged discard requests

Support requests with more than one bio payload for discards. The total
number of bytes to be discarded is stored in req->__data_len and used in
sd_done() to complete the I/O.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

1 files changed, 19 insertions, 13 deletions

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 12f6fdfc1147..c6af4c1a9ca3 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -583,29 +583,26 @@ static void sd_config_discard(struct scsi_disk *sdkp, unsigned int mode)
 }
 
 /**
- * scsi_setup_discard_cmnd - unmap blocks on thinly provisioned device
+ * sd_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 scsi_setup_discard_cmnd(struct scsi_device *sdp, struct request *rq)
+static int sd_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 nr_sectors = bio_sectors(bio);
+        sector_t sector = blk_rq_pos(rq);
+        unsigned int nr_sectors = blk_rq_sectors(rq);
+        unsigned int nr_bytes = blk_rq_bytes(rq);
         unsigned int len;
         int ret;
         char *buf;
         struct page *page;
 
-        if (sdkp->device->sector_size == 4096) {
-                sector >>= 3;
-                nr_sectors >>= 3;
-        }
-
+        sector >>= ilog2(sdp->sector_size) - 9;
+        nr_sectors >>= ilog2(sdp->sector_size) - 9;
         rq->timeout = SD_TIMEOUT;
 
         memset(rq->cmd, 0, rq->cmd_len);
@@ -660,6 +657,7 @@ static int scsi_setup_discard_cmnd(struct scsi_device *sdp, struct request *rq)
         blk_add_request_payload(rq, page, len);
         ret = scsi_setup_blk_pc_cmnd(sdp, rq);
         rq->buffer = page_address(page);
+        rq->__data_len = nr_bytes;
 
 out:
         if (ret != BLKPREP_OK) {
@@ -712,7 +710,7 @@ static int sd_prep_fn(struct request_queue *q, struct request *rq)
          * block PC requests to make life easier.
          */
         if (rq->cmd_flags & REQ_DISCARD) {
-                ret = scsi_setup_discard_cmnd(sdp, rq);
+                ret = sd_setup_discard_cmnd(sdp, rq);
                 goto out;
         } else if (rq->cmd_flags & REQ_FLUSH) {
                 ret = scsi_setup_flush_cmnd(sdp, rq);
@@ -1482,12 +1480,20 @@ static int sd_done(struct scsi_cmnd *SCpnt)
         unsigned int good_bytes = result ? 0 : scsi_bufflen(SCpnt);
         struct scsi_sense_hdr sshdr;
         struct scsi_disk *sdkp = scsi_disk(SCpnt->request->rq_disk);
+        struct request *req = SCpnt->request;
         int sense_valid = 0;
         int sense_deferred = 0;
         unsigned char op = SCpnt->cmnd[0];
 
-        if ((SCpnt->request->cmd_flags & REQ_DISCARD) && !result)
-                scsi_set_resid(SCpnt, 0);
+        if (req->cmd_flags & REQ_DISCARD) {
+                if (!result) {
+                        good_bytes = blk_rq_bytes(req);
+                        scsi_set_resid(SCpnt, 0);
+                } else {
+                        good_bytes = 0;
+                        scsi_set_resid(SCpnt, blk_rq_bytes(req));
+                }
+        }
 
         if (result) {
                 sense_valid = scsi_command_normalize_sense(SCpnt, &sshdr);