We can map the RESET WRITE POINTER command onto a 'discard'
request.

Signed-off-by: Hannes Reinecke <h...@suse.de>
---
 drivers/scsi/sd.c | 52 +++++++++++++++++++++++++++++++++++++++++++---------
 drivers/scsi/sd.h |  1 +
 2 files changed, 44 insertions(+), 9 deletions(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 74637fd..9220c66 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -369,6 +369,7 @@ static const char *lbp_mode[] = {
        [SD_LBP_WS16]           = "writesame_16",
        [SD_LBP_WS10]           = "writesame_10",
        [SD_LBP_ZERO]           = "writesame_zero",
+       [SD_ZBC_RESET_WP]       = "reset_wp",
        [SD_LBP_DISABLE]        = "disabled",
 };
 
@@ -391,6 +392,13 @@ provisioning_mode_store(struct device *dev, struct 
device_attribute *attr,
        if (!capable(CAP_SYS_ADMIN))
                return -EACCES;
 
+       if (sdkp->zoned == 1) {
+               if (!strncmp(buf, lbp_mode[SD_ZBC_RESET_WP], 20)) {
+                       sd_config_discard(sdkp, SD_ZBC_RESET_WP);
+                       return count;
+               }
+               return -EINVAL;
+       }
        if (sdp->type != TYPE_DISK)
                return -EINVAL;
 
@@ -683,6 +691,12 @@ static void sd_config_discard(struct scsi_disk *sdkp, 
unsigned int mode)
                q->limits.discard_zeroes_data = sdkp->lbprz;
                break;
 
+       case SD_ZBC_RESET_WP:
+               max_blocks = min_not_zero(sdkp->max_unmap_blocks,
+                                         (u32)SD_MAX_WS16_BLOCKS);
+               q->limits.discard_zeroes_data = 1;
+               break;
+
        case SD_LBP_ZERO:
                max_blocks = min_not_zero(sdkp->max_ws_blocks,
                                          (u32)SD_MAX_WS10_BLOCKS);
@@ -711,16 +725,18 @@ static int sd_setup_discard_cmnd(struct scsi_cmnd *cmd)
        unsigned int nr_sectors = blk_rq_sectors(rq);
        unsigned int nr_bytes = blk_rq_bytes(rq);
        unsigned int len;
-       int ret;
+       int ret = 0;
        char *buf;
-       struct page *page;
+       struct page *page = NULL;
 
        sector >>= ilog2(sdp->sector_size) - 9;
        nr_sectors >>= ilog2(sdp->sector_size) - 9;
 
-       page = alloc_page(GFP_ATOMIC | __GFP_ZERO);
-       if (!page)
-               return BLKPREP_DEFER;
+       if (sdkp->provisioning_mode != SD_ZBC_RESET_WP) {
+               page = alloc_page(GFP_ATOMIC | __GFP_ZERO);
+               if (!page)
+                       return BLKPREP_DEFER;
+       }
 
        switch (sdkp->provisioning_mode) {
        case SD_LBP_UNMAP:
@@ -760,6 +776,16 @@ static int sd_setup_discard_cmnd(struct scsi_cmnd *cmd)
                len = sdkp->device->sector_size;
                break;
 
+       case SD_ZBC_RESET_WP:
+               cmd->cmd_len = 16;
+               cmd->cmnd[0] = ZBC_OUT;
+               cmd->cmnd[1] = ZO_RESET_WRITE_POINTER;
+               put_unaligned_be64(sector, &cmd->cmnd[2]);
+               /* Reset Write Pointer doesn't have a payload */
+               len = 0;
+               cmd->sc_data_direction = DMA_NONE;
+               break;
+
        default:
                ret = BLKPREP_INVALID;
                goto out;
@@ -779,12 +805,14 @@ static int sd_setup_discard_cmnd(struct scsi_cmnd *cmd)
         * discarded on disk. This allows us to report completion on the full
         * amount of blocks described by the request.
         */
-       blk_add_request_payload(rq, page, len);
-       ret = scsi_init_io(cmd);
+       if (len) {
+               blk_add_request_payload(rq, page, len);
+               ret = scsi_init_io(cmd);
+       }
        rq->__data_len = nr_bytes;
 
 out:
-       if (ret != BLKPREP_OK)
+       if (page && ret != BLKPREP_OK)
                __free_page(page);
        return ret;
 }
@@ -1151,7 +1179,8 @@ static void sd_uninit_command(struct scsi_cmnd *SCpnt)
 {
        struct request *rq = SCpnt->request;
 
-       if (rq->cmd_flags & REQ_DISCARD)
+       if (rq->cmd_flags & REQ_DISCARD &&
+           rq->completion_data)
                __free_page(rq->completion_data);
 
        if (SCpnt->cmnd != rq->cmd) {
@@ -1768,6 +1797,7 @@ static int sd_done(struct scsi_cmnd *SCpnt)
        int sense_deferred = 0;
        unsigned char op = SCpnt->cmnd[0];
        unsigned char unmap = SCpnt->cmnd[1] & 8;
+       unsigned char sa = SCpnt->cmnd[1] & 0xf;
 
        if (req->cmd_flags & REQ_DISCARD || req->cmd_flags & REQ_WRITE_SAME) {
                if (!result) {
@@ -1819,6 +1849,10 @@ static int sd_done(struct scsi_cmnd *SCpnt)
                        case UNMAP:
                                sd_config_discard(sdkp, SD_LBP_DISABLE);
                                break;
+                       case ZBC_OUT:
+                               if (sa == ZO_RESET_WRITE_POINTER)
+                                       sd_config_discard(sdkp, SD_LBP_DISABLE);
+                               break;
                        case WRITE_SAME_16:
                        case WRITE_SAME:
                                if (unmap)
diff --git a/drivers/scsi/sd.h b/drivers/scsi/sd.h
index ab1696d..5debd49 100644
--- a/drivers/scsi/sd.h
+++ b/drivers/scsi/sd.h
@@ -56,6 +56,7 @@ enum {
        SD_LBP_WS16,            /* Use WRITE SAME(16) with UNMAP bit */
        SD_LBP_WS10,            /* Use WRITE SAME(10) with UNMAP bit */
        SD_LBP_ZERO,            /* Use WRITE SAME(10) with zero payload */
+       SD_ZBC_RESET_WP,        /* Use RESET WRITE POINTER */
        SD_LBP_DISABLE,         /* Discard disabled due to failed cmd */
 };
 
-- 
1.8.5.6

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