[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>

diff --git a/drivers/scsi/libata-scsi.c b/drivers/scsi/libata-scsi.c
index 90bf22204668c1828934c598db6492a9a1d96de7..efbe6fe65442cace7f1fe7c86c6580ee5408614b 100644 (file)
--- 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);

diff --git a/include/linux/ata.h b/include/linux/ata.h
index 630908c9378b45f3ed65bf1118171ff1cbd904dd..b7e7e1cb2633d8dd007264920c515f067b753267 100644 (file)
--- a/include/linux/ata.h
+++ b/include/linux/ata.h
@@ -291,4 +291,16 @@ static inline int ata_ok(u8 status)
                        == ATA_DRDY);
 }
 
+static inline int lba_28_ok(u64 block, u32 n_block)
+{
+       /* check the ending block number */
+       return ((block + n_block - 1) < ((u64)1 << 28)) && (n_block <= 256);
+}
+
+static inline int lba_48_ok(u64 block, u32 n_block)
+{
+       /* check the ending block number */
+       return ((block + n_block - 1) < ((u64)1 << 48)) && (n_block <= 65536);
+}
+
 #endif /* __LINUX_ATA_H__ */