ide: save the returned value of dma_map_sg

dma_map_sg could return a value different to 'nents' argument of
dma_map_sg so the ide stack needs to save it for the later usage
(e.g. for_each_sg).

The ide stack also needs to save the original sg_nents value for
pci_unmap_sg.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
[bart: backport to Linus' tree]
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

2 files changed, 10 insertions, 3 deletions

diff --git a/drivers/ide/ide-dma.c b/drivers/ide/ide-dma.c
index 72ebab0bc755..059c90bb5ad2 100644
--- a/drivers/ide/ide-dma.c
+++ b/drivers/ide/ide-dma.c
@@ -128,6 +128,7 @@ int ide_build_sglist(ide_drive_t *drive, struct request *rq)
 {
         ide_hwif_t *hwif = drive->hwif;
         struct scatterlist *sg = hwif->sg_table;
+        int i;
 
         ide_map_sg(drive, rq);
 
@@ -136,8 +137,13 @@ int ide_build_sglist(ide_drive_t *drive, struct request *rq)
         else
                 hwif->sg_dma_direction = DMA_TO_DEVICE;
 
-        return dma_map_sg(hwif->dev, sg, hwif->sg_nents,
-                          hwif->sg_dma_direction);
+        i = dma_map_sg(hwif->dev, sg, hwif->sg_nents, hwif->sg_dma_direction);
+        if (i) {
+                hwif->orig_sg_nents = hwif->sg_nents;
+                hwif->sg_nents = i;
+        }
+
+        return i;
 }
 EXPORT_SYMBOL_GPL(ide_build_sglist);
 
@@ -156,7 +162,7 @@ void ide_destroy_dmatable(ide_drive_t *drive)
 {
         ide_hwif_t *hwif = drive->hwif;
 
-        dma_unmap_sg(hwif->dev, hwif->sg_table, hwif->sg_nents,
+        dma_unmap_sg(hwif->dev, hwif->sg_table, hwif->orig_sg_nents,
                      hwif->sg_dma_direction);
 }
 EXPORT_SYMBOL_GPL(ide_destroy_dmatable);
diff --git a/include/linux/ide.h b/include/linux/ide.h
index e0cedfe9fad4..25087aead657 100644
--- a/include/linux/ide.h
+++ b/include/linux/ide.h
@@ -797,6 +797,7 @@ typedef struct hwif_s {
         struct scatterlist *sg_table;
         int sg_max_nents;               /* Maximum number of entries in it */
         int sg_nents;                   /* Current number of entries in it */
+        int orig_sg_nents;
         int sg_dma_direction;           /* dma transfer direction */
 
         /* data phase of the active command (currently only valid for PIO/DMA) */