libata: Use Maximum Write Same Length to report discard size limit

Previously we used Maximum Unmap LBA Count in the Block Limits VPD to
signal the maximum number of sectors we could handle in a single Write
Same command.

Starting with SBC3r26 the Block Limits VPD has an explicit limit on the
number of blocks in a Write Same. This means we can stop abusing a field
related to the Unmap command and let our SAT use the proper value in the
VPD (Maximum Write Same Length).

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
Cc: stable@kernel.org

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index e2f57e9e12f0eecb0fd8bbd2603ef14122ff003e..30ea95f43e7910cf8f4cdc1742d4213e53240fb5 100644 (file)
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -2138,7 +2138,7 @@ static unsigned int ata_scsiop_inq_b0(struct ata_scsi_args *args, u8 *rbuf)
         * with the unmap bit set.
         */
        if (ata_id_has_trim(args->id)) {
-               put_unaligned_be32(65535 * 512 / 8, &rbuf[20]);
+               put_unaligned_be64(65535 * 512 / 8, &rbuf[36]);
                put_unaligned_be32(1, &rbuf[28]);
        }