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>

1 files changed, 7 insertions, 1 deletions

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;