libata: add support for READ/WRITE LONG

The READ/WRITE LONG commands are theoretically obsolete,
but the majority of drives in existance still implement them.

The WRITE_LONG and WRITE_LONG_ONCE commands are of particular
interest for fault injection testing -- eg. creating "media errors"
at specific locations on a disk.

The fussy bit is that these commands require a non-standard
sector size, usually 520 bytes instead of 512.

This patch adds support to libata for READ/WRITE LONG commands
issued via SG_IO/ATA_16.

Signed-off-by:  Mark Lord <mlord@pobox.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 12 insertions, 0 deletions

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 7d41afe8ccbc..563ef0bfb038 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -2678,6 +2678,18 @@ static unsigned int ata_scsi_pass_thru(struct ata_queued_cmd *qc)
                 tf->device = qc->dev->devno ?
                         tf->device | ATA_DEV1 : tf->device & ~ATA_DEV1;
 
+        /* READ/WRITE LONG use a non-standard sect_size */
+        qc->sect_size = ATA_SECT_SIZE;
+        switch (tf->command) {
+        case ATA_CMD_READ_LONG:
+        case ATA_CMD_READ_LONG_ONCE:
+        case ATA_CMD_WRITE_LONG:
+        case ATA_CMD_WRITE_LONG_ONCE:
+                if (tf->protocol != ATA_PROT_PIO || tf->nsect != 1)
+                        goto invalid_fld;
+                qc->sect_size = scmd->request_bufflen;
+        }
+
         /*
          * Filter SET_FEATURES - XFER MODE command -- otherwise,
          * SET_FEATURES - XFER MODE must be preceded/succeeded