libata: Report zeroed read after TRIM and max discard size

Our current TRIM payload is a single sector that can accommodate 64 *
65535 blocks being unmapped.  Report this value in the Block Limits
Maximum Unmap LBA count field.

If a storage device supports TRIM and the DRAT and RZAT bits are set,
report TPRZ=1 in Read Capacity(16).

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

2 files changed, 20 insertions, 3 deletions

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 340a616d226b..e1e186b9dfcc 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -2115,8 +2115,10 @@ static unsigned int ata_scsiop_inq_b0(struct ata_scsi_args *args, u8 *rbuf)
          * that we support some form of unmap - in thise case via WRITE SAME
          * with the unmap bit set.
          */
-        if (ata_id_has_trim(args->id))
+        if (ata_id_has_trim(args->id)) {
+                put_unaligned_be32(65535 * 512 / 8, &rbuf[20]);
                 put_unaligned_be32(1, &rbuf[28]);
+        }
 
         return 0;
 }
@@ -2411,8 +2413,12 @@ static unsigned int ata_scsiop_read_cap(struct ata_scsi_args *args, u8 *rbuf)
                 rbuf[14] = (lowest_aligned >> 8) & 0x3f;
                 rbuf[15] = lowest_aligned;
 
-                if (ata_id_has_trim(args->id))
-                        rbuf[14] |= 0x80;
+                if (ata_id_has_trim(args->id)) {
+                        rbuf[14] |= 0x80; /* TPE */
+
+                        if (ata_id_has_zero_after_trim(args->id))
+                                rbuf[14] |= 0x40; /* TPRZ */
+                }
         }
 
         return 0;
diff --git a/include/linux/ata.h b/include/linux/ata.h
index e2595e877e44..dfa2298bf488 100644
--- a/include/linux/ata.h
+++ b/include/linux/ata.h
@@ -75,6 +75,7 @@ enum {
         ATA_ID_EIDE_DMA_TIME    = 66,
         ATA_ID_EIDE_PIO         = 67,
         ATA_ID_EIDE_PIO_IORDY   = 68,
+        ATA_ID_ADDITIONAL_SUPP  = 69,
         ATA_ID_QUEUE_DEPTH      = 75,
         ATA_ID_MAJOR_VER        = 80,
         ATA_ID_COMMAND_SET_1    = 82,
@@ -816,6 +817,16 @@ static inline int ata_id_has_trim(const u16 *id)
         return 0;
 }
 
+static inline int ata_id_has_zero_after_trim(const u16 *id)
+{
+        /* DSM supported, deterministic read, and read zero after trim set */
+        if (ata_id_has_trim(id) &&
+            (id[ATA_ID_ADDITIONAL_SUPP] & 0x4020) == 0x4020)
+                return 1;
+
+        return 0;
+}
+
 static inline int ata_id_current_chs_valid(const u16 *id)
 {
         /* For ATA-1 devices, if the INITIALIZE DEVICE PARAMETERS command