[SCSI] sd: Update thin provisioning support

Add support for the Thin Provisioning VPD page and use the TPU and TPWS
bits to switch between UNMAP and WRITE SAME(16) for discards.  If no TP
VPD page is present we fall back to old scheme where the max descriptor
count combined with the max lba count are used trigger UNMAP.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

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)