[PATCH] libata: fix READ CAPACITY simulation

* READ CAPACITY (16) implementation fixed.  Result was shifted by two
  bytes.  Carlos Pardo spotted this problem and submitted preliminary
  patch.  Capacity => 2TB is handled correctly now.  (verifid w/ fake
  capacity)

* Use dev->n_sectors instead of re-reading directly from ID data.

* Define and use ATA_SCSI_RBUF_SET() which considers rbuf length.
  This should be done for all simulation functions.  Userland can
  issue any simulated command with arbitrary buffer length.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Cc: Carlos Pardo <Carlos.Pardo@siliconimage.com>

1 files changed, 36 insertions, 45 deletions

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 56d7e1ea9d72..7ff1adfc729c 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -1698,6 +1698,22 @@ void ata_scsi_rbuf_fill(struct ata_scsi_args *args,
 }
 
 /**
+ *      ATA_SCSI_RBUF_SET - helper to set values in SCSI response buffer
+ *      @idx: byte index into SCSI response buffer
+ *      @val: value to set
+ *
+ *      To be used by SCSI command simulator functions.  This macros
+ *      expects two local variables, u8 *rbuf and unsigned int buflen,
+ *      are in scope.
+ *
+ *      LOCKING:
+ *      None.
+ */
+#define ATA_SCSI_RBUF_SET(idx, val) do { \
+                if ((idx) < buflen) rbuf[(idx)] = (u8)(val); \
+        } while (0)
+
+/**
  *      ata_scsiop_inq_std - Simulate INQUIRY command
  *      @args: device IDENTIFY data / SCSI command of interest.
  *      @rbuf: Response buffer, to which simulated SCSI cmd output is sent.
@@ -2156,67 +2172,42 @@ saving_not_supp:
  *      Simulate READ CAPACITY commands.
  *
  *      LOCKING:
- *      spin_lock_irqsave(host lock)
+ *      None.
  */
-
 unsigned int ata_scsiop_read_cap(struct ata_scsi_args *args, u8 *rbuf,
                                 unsigned int buflen)
 {
-        u64 n_sectors;
-        u32 tmp;
+        u64 last_lba = args->dev->n_sectors - 1; /* LBA of the last block */
 
         VPRINTK("ENTER\n");
 
-        if (ata_id_has_lba(args->id)) {
-                if (ata_id_has_lba48(args->id))
-                        n_sectors = ata_id_u64(args->id, 100);
-                else
-                        n_sectors = ata_id_u32(args->id, 60);
-        } else {
-                /* CHS default translation */
-                n_sectors = args->id[1] * args->id[3] * args->id[6];
-
-                if (ata_id_current_chs_valid(args->id))
-                        /* CHS current translation */
-                        n_sectors = ata_id_u32(args->id, 57);
-        }
-
-        n_sectors--;            /* ATA TotalUserSectors - 1 */
-
         if (args->cmd->cmnd[0] == READ_CAPACITY) {
-                if( n_sectors >= 0xffffffffULL )
-                        tmp = 0xffffffff ;  /* Return max count on overflow */
-                else
-                        tmp = n_sectors ;
+                if (last_lba >= 0xffffffffULL)
+                        last_lba = 0xffffffff;
 
                 /* sector count, 32-bit */
-                rbuf[0] = tmp >> (8 * 3);
-                rbuf[1] = tmp >> (8 * 2);
-                rbuf[2] = tmp >> (8 * 1);
-                rbuf[3] = tmp;
+                ATA_SCSI_RBUF_SET(0, last_lba >> (8 * 3));
+                ATA_SCSI_RBUF_SET(1, last_lba >> (8 * 2));
+                ATA_SCSI_RBUF_SET(2, last_lba >> (8 * 1));
+                ATA_SCSI_RBUF_SET(3, last_lba);
 
                 /* sector size */
-                tmp = ATA_SECT_SIZE;
-                rbuf[6] = tmp >> 8;
-                rbuf[7] = tmp;
-
+                ATA_SCSI_RBUF_SET(6, ATA_SECT_SIZE >> 8);
+                ATA_SCSI_RBUF_SET(7, ATA_SECT_SIZE);
         } else {
                 /* sector count, 64-bit */
-                tmp = n_sectors >> (8 * 4);
-                rbuf[2] = tmp >> (8 * 3);
-                rbuf[3] = tmp >> (8 * 2);
-                rbuf[4] = tmp >> (8 * 1);
-                rbuf[5] = tmp;
-                tmp = n_sectors;
-                rbuf[6] = tmp >> (8 * 3);
-                rbuf[7] = tmp >> (8 * 2);
-                rbuf[8] = tmp >> (8 * 1);
-                rbuf[9] = tmp;
+                ATA_SCSI_RBUF_SET(0, last_lba >> (8 * 7));
+                ATA_SCSI_RBUF_SET(1, last_lba >> (8 * 6));
+                ATA_SCSI_RBUF_SET(2, last_lba >> (8 * 5));
+                ATA_SCSI_RBUF_SET(3, last_lba >> (8 * 4));
+                ATA_SCSI_RBUF_SET(4, last_lba >> (8 * 3));
+                ATA_SCSI_RBUF_SET(5, last_lba >> (8 * 2));
+                ATA_SCSI_RBUF_SET(6, last_lba >> (8 * 1));
+                ATA_SCSI_RBUF_SET(7, last_lba);
 
                 /* sector size */
-                tmp = ATA_SECT_SIZE;
-                rbuf[12] = tmp >> 8;
-                rbuf[13] = tmp;
+                ATA_SCSI_RBUF_SET(10, ATA_SECT_SIZE >> 8);
+                ATA_SCSI_RBUF_SET(11, ATA_SECT_SIZE);
         }
 
         return 0;