1 files changed, 26 insertions, 11 deletions

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 11c1738c2100..d175c5c5ccf8 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -715,13 +715,21 @@ static void sd_config_discard(struct scsi_disk *sdkp, unsigned int mode)
                 break;
 
         case SD_LBP_WS16:
-                max_blocks = min_not_zero(sdkp->max_ws_blocks,
-                                          (u32)SD_MAX_WS16_BLOCKS);
+                if (sdkp->device->unmap_limit_for_ws)
+                        max_blocks = sdkp->max_unmap_blocks;
+                else
+                        max_blocks = sdkp->max_ws_blocks;
+
+                max_blocks = min_not_zero(max_blocks, (u32)SD_MAX_WS16_BLOCKS);
                 break;
 
         case SD_LBP_WS10:
-                max_blocks = min_not_zero(sdkp->max_ws_blocks,
-                                          (u32)SD_MAX_WS10_BLOCKS);
+                if (sdkp->device->unmap_limit_for_ws)
+                        max_blocks = sdkp->max_unmap_blocks;
+                else
+                        max_blocks = sdkp->max_ws_blocks;
+
+                max_blocks = min_not_zero(max_blocks, (u32)SD_MAX_WS10_BLOCKS);
                 break;
 
         case SD_LBP_ZERO:
@@ -2915,8 +2923,6 @@ static void sd_read_block_limits(struct scsi_disk *sdkp)
                                 sd_config_discard(sdkp, SD_LBP_WS16);
                         else if (sdkp->lbpws10)
                                 sd_config_discard(sdkp, SD_LBP_WS10);
-                        else if (sdkp->lbpu && sdkp->max_unmap_blocks)
-                                sd_config_discard(sdkp, SD_LBP_UNMAP);
                         else
                                 sd_config_discard(sdkp, SD_LBP_DISABLE);
                 }
@@ -3101,8 +3107,6 @@ static int sd_revalidate_disk(struct gendisk *disk)
                 sd_read_security(sdkp, buffer);
         }
 
-        sdkp->first_scan = 0;
-
         /*
          * We now have all cache related info, determine how we deal
          * with flush requests.
@@ -3117,7 +3121,7 @@ static int sd_revalidate_disk(struct gendisk *disk)
         q->limits.max_dev_sectors = logical_to_sectors(sdp, dev_max);
 
         /*
-         * Use the device's preferred I/O size for reads and writes
+         * Determine the device's preferred I/O size for reads and writes
          * unless the reported value is unreasonably small, large, or
          * garbage.
          */
@@ -3131,8 +3135,19 @@ static int sd_revalidate_disk(struct gendisk *disk)
                 rw_max = min_not_zero(logical_to_sectors(sdp, dev_max),
                                       (sector_t)BLK_DEF_MAX_SECTORS);
 
-        /* Combine with controller limits */
-        q->limits.max_sectors = min(rw_max, queue_max_hw_sectors(q));
+        /* Do not exceed controller limit */
+        rw_max = min(rw_max, queue_max_hw_sectors(q));
+
+        /*
+         * Only update max_sectors if previously unset or if the current value
+         * exceeds the capabilities of the hardware.
+         */
+        if (sdkp->first_scan ||
+            q->limits.max_sectors > q->limits.max_dev_sectors ||
+            q->limits.max_sectors > q->limits.max_hw_sectors)
+                q->limits.max_sectors = rw_max;
+
+        sdkp->first_scan = 0;
 
         set_capacity(disk, logical_to_sectors(sdp, sdkp->capacity));
         sd_config_write_same(sdkp);