IDE: sg chaining support

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

9 files changed, 25 insertions, 12 deletions

diff --git a/drivers/ide/cris/ide-cris.c b/drivers/ide/cris/ide-cris.c
index 2b4d2a0ae5c2..c306c9f534ab 100644
--- a/drivers/ide/cris/ide-cris.c
+++ b/drivers/ide/cris/ide-cris.c
@@ -939,7 +939,8 @@ static int cris_ide_build_dmatable (ide_drive_t *drive)
                 /* group sequential buffers into one large buffer */
                 addr = page_to_phys(sg->page) + sg->offset;
                 size = sg_dma_len(sg);
-                while (sg++, --i) {
+                while (--i) {
+                        sg = sg_next(sg);
                         if ((addr + size) != page_to_phys(sg->page) + sg->offset)
                                 break;
                         size += sg_dma_len(sg);
diff --git a/drivers/ide/ide-dma.c b/drivers/ide/ide-dma.c
index b453211ee0fc..a4cbbbaccde9 100644
--- a/drivers/ide/ide-dma.c
+++ b/drivers/ide/ide-dma.c
@@ -280,7 +280,7 @@ int ide_build_dmatable (ide_drive_t *drive, struct request *rq)
                         }
                 }
 
-                sg++;
+                sg = sg_next(sg);
                 i--;
         }
 
diff --git a/drivers/ide/ide-io.c b/drivers/ide/ide-io.c
index f36ff5962af6..04273d3c147c 100644
--- a/drivers/ide/ide-io.c
+++ b/drivers/ide/ide-io.c
@@ -846,7 +846,8 @@ void ide_init_sg_cmd(ide_drive_t *drive, struct request *rq)
         ide_hwif_t *hwif = drive->hwif;
 
         hwif->nsect = hwif->nleft = rq->nr_sectors;
-        hwif->cursg = hwif->cursg_ofs = 0;
+        hwif->cursg_ofs = 0;
+        hwif->cursg = NULL;
 }
 
 EXPORT_SYMBOL_GPL(ide_init_sg_cmd);
diff --git a/drivers/ide/ide-probe.c b/drivers/ide/ide-probe.c
index d1011712601c..34b1fb65bc79 100644
--- a/drivers/ide/ide-probe.c
+++ b/drivers/ide/ide-probe.c
@@ -1349,7 +1349,7 @@ static int hwif_init(ide_hwif_t *hwif)
         if (!hwif->sg_max_nents)
                 hwif->sg_max_nents = PRD_ENTRIES;
 
-        hwif->sg_table = kmalloc(sizeof(struct scatterlist)*hwif->sg_max_nents,
+        hwif->sg_table = kzalloc(sizeof(struct scatterlist)*hwif->sg_max_nents,
                                  GFP_KERNEL);
         if (!hwif->sg_table) {
                 printk(KERN_ERR "%s: unable to allocate SG table.\n", hwif->name);
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;
 
diff --git a/drivers/ide/mips/au1xxx-ide.c b/drivers/ide/mips/au1xxx-ide.c
index aebde49365d1..892d08f61dc0 100644
--- a/drivers/ide/mips/au1xxx-ide.c
+++ b/drivers/ide/mips/au1xxx-ide.c
@@ -296,7 +296,7 @@ static int auide_build_dmatable(ide_drive_t *drive)
                         cur_addr += tc;
                         cur_len -= tc;
                 }
-                sg++;
+                sg = sg_next(sg);
                 i--;
         }
 
diff --git a/drivers/ide/pci/sgiioc4.c b/drivers/ide/pci/sgiioc4.c
index 85ffaaa39b1b..c74fef6bbc91 100644
--- a/drivers/ide/pci/sgiioc4.c
+++ b/drivers/ide/pci/sgiioc4.c
@@ -29,6 +29,7 @@
 #include <linux/mm.h>
 #include <linux/ioport.h>
 #include <linux/blkdev.h>
+#include <linux/scatterlist.h>
 #include <linux/ioc4.h>
 #include <asm/io.h>
 
@@ -537,7 +538,7 @@ sgiioc4_build_dma_table(ide_drive_t * drive, struct request *rq, int ddir)
                         }
                 }
 
-                sg++;
+                sg = sg_next(sg);
                 i--;
         }
 
diff --git a/drivers/ide/ppc/pmac.c b/drivers/ide/ppc/pmac.c
index 7d8873839e21..9e86406bf44b 100644
--- a/drivers/ide/ppc/pmac.c
+++ b/drivers/ide/ppc/pmac.c
@@ -1539,7 +1539,7 @@ pmac_ide_build_dmatable(ide_drive_t *drive, struct request *rq)
                         cur_len -= tc;
                         ++table;
                 }
-                sg++;
+                sg = sg_next(sg);
                 i--;
         }
 
diff --git a/include/linux/ide.h b/include/linux/ide.h
index 234fa3df24f6..30a1931466a6 100644
--- a/include/linux/ide.h
+++ b/include/linux/ide.h
@@ -772,7 +772,7 @@ typedef struct hwif_s {
 
         unsigned int nsect;
         unsigned int nleft;
-        unsigned int cursg;
+        struct scatterlist *cursg;
         unsigned int cursg_ofs;
 
         int             rqsize;         /* max sectors per request */