libata: implement ata_qc_raw_nbytes()

Implement ata_qc_raw_nbytes() which determines the raw user-requested
size of a PC command.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

2 files changed, 18 insertions, 4 deletions

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 8f0e8f2bc628..15795394b0a8 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -527,6 +527,14 @@ static struct ata_queued_cmd *ata_scsi_qc_new(struct ata_device *dev,
         return qc;
 }
 
+static void ata_qc_set_pc_nbytes(struct ata_queued_cmd *qc)
+{
+        struct scsi_cmnd *scmd = qc->scsicmd;
+
+        qc->extrabytes = scmd->request->extra_len;
+        qc->nbytes = scsi_bufflen(scmd) + qc->extrabytes;
+}
+
 /**
  *      ata_dump_status - user friendly display of error info
  *      @id: id of the port in question
@@ -2539,7 +2547,7 @@ static unsigned int atapi_xlat(struct ata_queued_cmd *qc)
         }
 
         qc->tf.command = ATA_CMD_PACKET;
-        qc->nbytes = scsi_bufflen(scmd) + scmd->request->extra_len;
+        ata_qc_set_pc_nbytes(qc);
 
         /* check whether ATAPI DMA is safe */
         if (!using_pio && ata_check_atapi_dma(qc))
@@ -2550,7 +2558,7 @@ static unsigned int atapi_xlat(struct ata_queued_cmd *qc)
          * want to set it properly, and for DMA where it is
          * effectively meaningless.
          */
-        nbytes = min(scmd->request->data_len, (unsigned int)63 * 1024);
+        nbytes = min(ata_qc_raw_nbytes(qc), (unsigned int)63 * 1024);
 
         /* Most ATAPI devices which honor transfer chunk size don't
          * behave according to the spec when odd chunk size which
@@ -2876,7 +2884,7 @@ static unsigned int ata_scsi_pass_thru(struct ata_queued_cmd *qc)
          * TODO: find out if we need to do more here to
          *       cover scatter/gather case.
          */
-        qc->nbytes = scsi_bufflen(scmd) + scmd->request->extra_len;
+        ata_qc_set_pc_nbytes(qc);
 
         /* request result TF and be quiet about device error */
         qc->flags |= ATA_QCFLAG_RESULT_TF | ATA_QCFLAG_QUIET;
diff --git a/include/linux/libata.h b/include/linux/libata.h
index a05f60013642..269cdba09578 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -463,6 +463,7 @@ struct ata_queued_cmd {
         unsigned int            sect_size;
 
         unsigned int            nbytes;
+        unsigned int            extrabytes;
         unsigned int            curbytes;
 
         struct scatterlist      *cursg;
@@ -1336,6 +1337,11 @@ static inline struct ata_queued_cmd *ata_qc_from_tag(struct ata_port *ap,
         return NULL;
 }
 
+static inline unsigned int ata_qc_raw_nbytes(struct ata_queued_cmd *qc)
+{
+        return qc->nbytes - min(qc->extrabytes, qc->nbytes);
+}
+
 static inline void ata_tf_init(struct ata_device *dev, struct ata_taskfile *tf)
 {
         memset(tf, 0, sizeof(*tf));
@@ -1354,7 +1360,7 @@ static inline void ata_qc_reinit(struct ata_queued_cmd *qc)
         qc->flags = 0;
         qc->cursg = NULL;
         qc->cursg_ofs = 0;
-        qc->nbytes = qc->curbytes = 0;
+        qc->nbytes = qc->extrabytes = qc->curbytes = 0;
         qc->n_elem = 0;
         qc->err_mask = 0;
         qc->sect_size = ATA_SECT_SIZE;