USB storage: sg chaining support

[PATCH] USB storage: sg chaining support

Modify usb_stor_access_xfer_buf() to take a pointer to an sg
entry pointer, so we can keep track of that instead of passing
around an integer index (which we can't use when dealing with
multiple scatterlist arrays).

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 8 insertions, 9 deletions

diff --git a/drivers/usb/storage/shuttle_usbat.c b/drivers/usb/storage/shuttle_usbat.c
index 17ca4d73577b..cb22a9ad1694 100644
--- a/drivers/usb/storage/shuttle_usbat.c
+++ b/drivers/usb/storage/shuttle_usbat.c
@@ -993,7 +993,8 @@ static int usbat_flash_read_data(struct us_data *us,
         unsigned char  thistime;
         unsigned int totallen, alloclen;
         int len, result;
-        unsigned int sg_idx = 0, sg_offset = 0;
+        unsigned int sg_offset = 0;
+        struct scatterlist *sg = NULL;
 
         result = usbat_flash_check_media(us, info);
         if (result != USB_STOR_TRANSPORT_GOOD)
@@ -1047,7 +1048,7 @@ static int usbat_flash_read_data(struct us_data *us,
         
                 /* Store the data in the transfer buffer */
                 usb_stor_access_xfer_buf(buffer, len, us->srb,
-                                         &sg_idx, &sg_offset, TO_XFER_BUF);
+                                         &sg, &sg_offset, TO_XFER_BUF);
 
                 sector += thistime;
                 totallen -= len;
@@ -1083,7 +1084,8 @@ static int usbat_flash_write_data(struct us_data *us,
         unsigned char  thistime;
         unsigned int totallen, alloclen;
         int len, result;
-        unsigned int sg_idx = 0, sg_offset = 0;
+        unsigned int sg_offset = 0;
+        struct scatterlist *sg = NULL;
 
         result = usbat_flash_check_media(us, info);
         if (result != USB_STOR_TRANSPORT_GOOD)
@@ -1122,7 +1124,7 @@ static int usbat_flash_write_data(struct us_data *us,
 
                 /* Get the data from the transfer buffer */
                 usb_stor_access_xfer_buf(buffer, len, us->srb,
-                                         &sg_idx, &sg_offset, FROM_XFER_BUF);
+                                         &sg, &sg_offset, FROM_XFER_BUF);
 
                 /* ATA command 0x30 (WRITE SECTORS) */
                 usbat_pack_ata_sector_cmd(command, thistime, sector, 0x30);
@@ -1162,8 +1164,8 @@ static int usbat_hp8200e_handle_read10(struct us_data *us,
         unsigned char *buffer;
         unsigned int len;
         unsigned int sector;
-        unsigned int sg_segment = 0;
         unsigned int sg_offset = 0;
+        struct scatterlist *sg = NULL;
 
         US_DEBUGP("handle_read10: transfersize %d\n",
                 srb->transfersize);
@@ -1220,9 +1222,6 @@ static int usbat_hp8200e_handle_read10(struct us_data *us,
         sector |= short_pack(data[7+5], data[7+4]);
         transferred = 0;
 
-        sg_segment = 0; /* for keeping track of where we are in */
-        sg_offset = 0;  /* the scatter/gather list */
-
         while (transferred != srb->request_bufflen) {
 
                 if (len > srb->request_bufflen - transferred)
@@ -1255,7 +1254,7 @@ static int usbat_hp8200e_handle_read10(struct us_data *us,
 
                 /* Store the data in the transfer buffer */
                 usb_stor_access_xfer_buf(buffer, len, srb,
-                                 &sg_segment, &sg_offset, TO_XFER_BUF);
+                                 &sg, &sg_offset, TO_XFER_BUF);
 
                 /* Update the amount transferred and the sector number */