2 files changed, 44 insertions, 5 deletions

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 8c9b275f71a7..0c4f89cfb7dc 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -2039,14 +2039,24 @@ static void sd_read_block_limits(struct scsi_disk *sdkp)
                 lba_count = get_unaligned_be32(&buffer[20]);
                 desc_count = get_unaligned_be32(&buffer[24]);
 
-                if (lba_count) {
-                        q->limits.max_discard_sectors =
-                                lba_count * sector_sz >> 9;
-
-                        if (desc_count)
+                if (lba_count && desc_count) {
+                        if (sdkp->tpvpd && !sdkp->tpu)
+                                sdkp->unmap = 0;
+                        else
                                 sdkp->unmap = 1;
                 }
 
+                if (sdkp->tpvpd && !sdkp->tpu && !sdkp->tpws) {
+                        sd_printk(KERN_ERR, sdkp, "Thin provisioning is " \
+                                  "enabled but neither TPU, nor TPWS are " \
+                                  "set. Disabling discard!\n");
+                        goto out;
+                }
+
+                if (lba_count)
+                        q->limits.max_discard_sectors =
+                                lba_count * sector_sz >> 9;
+
                 granularity = get_unaligned_be32(&buffer[28]);
 
                 if (granularity)
@@ -2087,6 +2097,31 @@ static void sd_read_block_characteristics(struct scsi_disk *sdkp)
         kfree(buffer);
 }
 
+/**
+ * sd_read_thin_provisioning - Query thin provisioning VPD page
+ * @disk: disk to query
+ */
+static void sd_read_thin_provisioning(struct scsi_disk *sdkp)
+{
+        unsigned char *buffer;
+        const int vpd_len = 8;
+
+        if (sdkp->thin_provisioning == 0)
+                return;
+
+        buffer = kmalloc(vpd_len, GFP_KERNEL);
+
+        if (!buffer || scsi_get_vpd_page(sdkp->device, 0xb2, buffer, vpd_len))
+                goto out;
+
+        sdkp->tpvpd = 1;
+        sdkp->tpu   = (buffer[5] >> 7) & 1;     /* UNMAP */
+        sdkp->tpws  = (buffer[5] >> 6) & 1;     /* WRITE SAME(16) with UNMAP */
+
+ out:
+        kfree(buffer);
+}
+
 static int sd_try_extended_inquiry(struct scsi_device *sdp)
 {
         /*
@@ -2138,6 +2173,7 @@ static int sd_revalidate_disk(struct gendisk *disk)
                 sd_read_capacity(sdkp, buffer);
 
                 if (sd_try_extended_inquiry(sdp)) {
+                        sd_read_thin_provisioning(sdkp);
                         sd_read_block_limits(sdkp);
                         sd_read_block_characteristics(sdkp);
                 }
diff --git a/drivers/scsi/sd.h b/drivers/scsi/sd.h
index 315ce9d96b1f..a40730ee465c 100644
--- a/drivers/scsi/sd.h
+++ b/drivers/scsi/sd.h
@@ -63,6 +63,9 @@ struct scsi_disk {
         unsigned        first_scan : 1;
         unsigned        thin_provisioning : 1;
         unsigned        unmap : 1;
+        unsigned        tpws : 1;
+        unsigned        tpu : 1;
+        unsigned        tpvpd : 1;
 };
 #define to_scsi_disk(obj) container_of(obj,struct scsi_disk,dev)