IDE: sg chaining support

Acked-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 14 insertions, 4 deletions

diff --git a/drivers/ide/ide-taskfile.c b/drivers/ide/ide-taskfile.c
index aa06dafb74ac..2a3c8d498343 100644
--- a/drivers/ide/ide-taskfile.c
+++ b/drivers/ide/ide-taskfile.c
@@ -45,6 +45,7 @@
 #include <linux/hdreg.h>
 #include <linux/ide.h>
 #include <linux/bitops.h>
+#include <linux/scatterlist.h>
 
 #include <asm/byteorder.h>
 #include <asm/irq.h>
@@ -263,6 +264,7 @@ static void ide_pio_sector(ide_drive_t *drive, unsigned int write)
 {
         ide_hwif_t *hwif = drive->hwif;
         struct scatterlist *sg = hwif->sg_table;
+        struct scatterlist *cursg = hwif->cursg;
         struct page *page;
 #ifdef CONFIG_HIGHMEM
         unsigned long flags;
@@ -270,8 +272,14 @@ static void ide_pio_sector(ide_drive_t *drive, unsigned int write)
         unsigned int offset;
         u8 *buf;
 
-        page = sg[hwif->cursg].page;
-        offset = sg[hwif->cursg].offset + hwif->cursg_ofs * SECTOR_SIZE;
+        cursg = hwif->cursg;
+        if (!cursg) {
+                cursg = sg;
+                hwif->cursg = sg;
+        }
+
+        page = cursg->page;
+        offset = cursg->offset + hwif->cursg_ofs * SECTOR_SIZE;
 
         /* get the current page and offset */
         page = nth_page(page, (offset >> PAGE_SHIFT));
@@ -285,8 +293,8 @@ static void ide_pio_sector(ide_drive_t *drive, unsigned int write)
         hwif->nleft--;
         hwif->cursg_ofs++;
 
-        if ((hwif->cursg_ofs * SECTOR_SIZE) == sg[hwif->cursg].length) {
-                hwif->cursg++;
+        if ((hwif->cursg_ofs * SECTOR_SIZE) == cursg->length) {
+                hwif->cursg = sg_next(hwif->cursg);
                 hwif->cursg_ofs = 0;
         }
 
@@ -367,6 +375,8 @@ static ide_startstop_t task_error(ide_drive_t *drive, struct request *rq,
 
 static void task_end_request(ide_drive_t *drive, struct request *rq, u8 stat)
 {
+        HWIF(drive)->cursg = NULL;
+
         if (rq->cmd_type == REQ_TYPE_ATA_TASKFILE) {
                 ide_task_t *task = rq->special;