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, 10 insertions, 6 deletions

diff --git a/drivers/usb/storage/alauda.c b/drivers/usb/storage/alauda.c
index 4d3cbb12b713..8d3711a7ff06 100644
--- a/drivers/usb/storage/alauda.c
+++ b/drivers/usb/storage/alauda.c
@@ -798,12 +798,13 @@ static int alauda_read_data(struct us_data *us, unsigned long address,
 {
         unsigned char *buffer;
         u16 lba, max_lba;
-        unsigned int page, len, index, offset;
+        unsigned int page, len, offset;
         unsigned int blockshift = MEDIA_INFO(us).blockshift;
         unsigned int pageshift = MEDIA_INFO(us).pageshift;
         unsigned int blocksize = MEDIA_INFO(us).blocksize;
         unsigned int pagesize = MEDIA_INFO(us).pagesize;
         unsigned int uzonesize = MEDIA_INFO(us).uzonesize;
+        struct scatterlist *sg;
         int result;
 
         /*
@@ -827,7 +828,8 @@ static int alauda_read_data(struct us_data *us, unsigned long address,
         max_lba = MEDIA_INFO(us).capacity >> (blockshift + pageshift);
 
         result = USB_STOR_TRANSPORT_GOOD;
-        index = offset = 0;
+        offset = 0;
+        sg = NULL;
 
         while (sectors > 0) {
                 unsigned int zone = lba / uzonesize; /* integer division */
@@ -873,7 +875,7 @@ static int alauda_read_data(struct us_data *us, unsigned long address,
 
                 /* Store the data in the transfer buffer */
                 usb_stor_access_xfer_buf(buffer, len, us->srb,
-                                &index, &offset, TO_XFER_BUF);
+                                &sg, &offset, TO_XFER_BUF);
 
                 page = 0;
                 lba++;
@@ -891,11 +893,12 @@ static int alauda_write_data(struct us_data *us, unsigned long address,
                 unsigned int sectors)
 {
         unsigned char *buffer, *blockbuffer;
-        unsigned int page, len, index, offset;
+        unsigned int page, len, offset;
         unsigned int blockshift = MEDIA_INFO(us).blockshift;
         unsigned int pageshift = MEDIA_INFO(us).pageshift;
         unsigned int blocksize = MEDIA_INFO(us).blocksize;
         unsigned int pagesize = MEDIA_INFO(us).pagesize;
+        struct scatterlist *sg;
         u16 lba, max_lba;
         int result;
 
@@ -929,7 +932,8 @@ static int alauda_write_data(struct us_data *us, unsigned long address,
         max_lba = MEDIA_INFO(us).capacity >> (pageshift + blockshift);
 
         result = USB_STOR_TRANSPORT_GOOD;
-        index = offset = 0;
+        offset = 0;
+        sg = NULL;
 
         while (sectors > 0) {
                 /* Write as many sectors as possible in this block */
@@ -946,7 +950,7 @@ static int alauda_write_data(struct us_data *us, unsigned long address,
 
                 /* Get the data from the transfer buffer */
                 usb_stor_access_xfer_buf(buffer, len, us->srb,
-                                &index, &offset, FROM_XFER_BUF);
+                                &sg, &offset, FROM_XFER_BUF);
 
                 result = alauda_write_lba(us, lba, page, pages, buffer,
                         blockbuffer);