[PATCH] libata CHS: LBA28/LBA48 optimization (revise #6)

     - add lba_28_ok() and lba_48_ok() to ata.h.
     - check ending block number instead of staring block number.
     - use lba_28_ok() for CHS range check
     - LBA28/LBA48 optimization

Suggested by Mark Lord and Alan Cox.

Signed-off-by: Albert Lee <albertcc@tw.ibm.com>

=====
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>

1 files changed, 21 insertions, 27 deletions

diff --git a/drivers/scsi/libata-scsi.c b/drivers/scsi/libata-scsi.c
index 90bf22204668..efbe6fe65442 100644
--- a/drivers/scsi/libata-scsi.c
+++ b/drivers/scsi/libata-scsi.c
@@ -636,9 +636,13 @@ static unsigned int ata_scsi_verify_xlat(struct ata_queued_cmd *qc, u8 *scsicmd)
         if (dev->flags & ATA_DFLAG_LBA) {
                 tf->flags |= ATA_TFLAG_LBA;
 
-                if (dev->flags & ATA_DFLAG_LBA48) {
-                        if (n_block > (64 * 1024))
-                                goto invalid_fld;
+                if (lba_28_ok(block, n_block)) {
+                        /* use LBA28 */
+                        tf->command = ATA_CMD_VERIFY;
+                        tf->device |= (block >> 24) & 0xf;
+                } else if (lba_48_ok(block, n_block)) {
+                        if (!(dev->flags & ATA_DFLAG_LBA48))
+                                goto out_of_range;
 
                         /* use LBA48 */
                         tf->flags |= ATA_TFLAG_LBA48;
@@ -649,15 +653,9 @@ static unsigned int ata_scsi_verify_xlat(struct ata_queued_cmd *qc, u8 *scsicmd)
                         tf->hob_lbah = (block >> 40) & 0xff;
                         tf->hob_lbam = (block >> 32) & 0xff;
                         tf->hob_lbal = (block >> 24) & 0xff;
-                } else {
-                        if (n_block > 256)
-                                goto invalid_fld;
-
-                        /* use LBA28 */
-                        tf->command = ATA_CMD_VERIFY;
-
-                        tf->device |= (block >> 24) & 0xf;
-                }
+                } else
+                        /* request too large even for LBA48 */
+                        goto out_of_range;
 
                 tf->nsect = n_block & 0xff;
 
@@ -670,8 +668,8 @@ static unsigned int ata_scsi_verify_xlat(struct ata_queued_cmd *qc, u8 *scsicmd)
                 /* CHS */
                 u32 sect, head, cyl, track;
 
-                if (n_block > 256)
-                        goto invalid_fld;
+                if (!lba_28_ok(block, n_block))
+                        goto out_of_range;
 
                 /* Convert LBA to CHS */
                 track = (u32)block / dev->sectors;
@@ -784,9 +782,11 @@ static unsigned int ata_scsi_rw_xlat(struct ata_queued_cmd *qc, u8 *scsicmd)
         if (dev->flags & ATA_DFLAG_LBA) {
                 tf->flags |= ATA_TFLAG_LBA;
 
-                if (dev->flags & ATA_DFLAG_LBA48) {
-                        /* The request -may- be too large for LBA48. */
-                        if ((block >> 48) || (n_block > 65536))
+                if (lba_28_ok(block, n_block)) {
+                        /* use LBA28 */
+                        tf->device |= (block >> 24) & 0xf;
+                } else if (lba_48_ok(block, n_block)) {
+                        if (!(dev->flags & ATA_DFLAG_LBA48))
                                 goto out_of_range;
 
                         /* use LBA48 */
@@ -797,15 +797,9 @@ static unsigned int ata_scsi_rw_xlat(struct ata_queued_cmd *qc, u8 *scsicmd)
                         tf->hob_lbah = (block >> 40) & 0xff;
                         tf->hob_lbam = (block >> 32) & 0xff;
                         tf->hob_lbal = (block >> 24) & 0xff;
-                } else { 
-                        /* use LBA28 */
-
-                        /* The request -may- be too large for LBA28. */
-                        if ((block >> 28) || (n_block > 256))
-                                goto out_of_range;
-
-                        tf->device |= (block >> 24) & 0xf;
-                }
+                } else
+                        /* request too large even for LBA48 */
+                        goto out_of_range;
 
                 ata_rwcmd_protocol(qc);
 
@@ -822,7 +816,7 @@ static unsigned int ata_scsi_rw_xlat(struct ata_queued_cmd *qc, u8 *scsicmd)
                 u32 sect, head, cyl, track;
 
                 /* The request -may- be too large for CHS addressing. */
-                if ((block >> 28) || (n_block > 256))
+                if (!lba_28_ok(block, n_block))
                         goto out_of_range;
 
                 ata_rwcmd_protocol(qc);