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authorJens Axboe <jens.axboe@oracle.com>2007-05-11 12:33:09 +0200
committerJens Axboe <jens.axboe@oracle.com>2007-10-16 11:20:59 +0200
commit1f6f31a03e3aed0854a6aa3ab763c3d3b2ff42ff (patch)
treebdb94c08e0bce7c17f686aabc274a7554718407b /drivers/usb/storage/protocol.c
parent53d412fce05e73dd0b25b0ebfa83c7ee94f16451 (diff)
downloadlinux-1f6f31a03e3aed0854a6aa3ab763c3d3b2ff42ff.tar.bz2
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>
Diffstat (limited to 'drivers/usb/storage/protocol.c')
-rw-r--r--drivers/usb/storage/protocol.c20
1 files changed, 11 insertions, 9 deletions
diff --git a/drivers/usb/storage/protocol.c b/drivers/usb/storage/protocol.c
index 9ad30428d2dd..cc8f7c52c729 100644
--- a/drivers/usb/storage/protocol.c
+++ b/drivers/usb/storage/protocol.c
@@ -157,7 +157,7 @@ void usb_stor_transparent_scsi_command(struct scsi_cmnd *srb,
* pick up from where this one left off. */
unsigned int usb_stor_access_xfer_buf(unsigned char *buffer,
- unsigned int buflen, struct scsi_cmnd *srb, unsigned int *index,
+ unsigned int buflen, struct scsi_cmnd *srb, struct scatterlist **sgptr,
unsigned int *offset, enum xfer_buf_dir dir)
{
unsigned int cnt;
@@ -184,16 +184,17 @@ unsigned int usb_stor_access_xfer_buf(unsigned char *buffer,
* located in high memory -- then kmap() will map it to a temporary
* position in the kernel's virtual address space. */
} else {
- struct scatterlist *sg =
- (struct scatterlist *) srb->request_buffer
- + *index;
+ struct scatterlist *sg = *sgptr;
+
+ if (!sg)
+ sg = (struct scatterlist *) srb->request_buffer;
/* This loop handles a single s-g list entry, which may
* include multiple pages. Find the initial page structure
* and the starting offset within the page, and update
* the *offset and *index values for the next loop. */
cnt = 0;
- while (cnt < buflen && *index < srb->use_sg) {
+ while (cnt < buflen) {
struct page *page = sg->page +
((sg->offset + *offset) >> PAGE_SHIFT);
unsigned int poff =
@@ -209,8 +210,7 @@ unsigned int usb_stor_access_xfer_buf(unsigned char *buffer,
/* Transfer continues to next s-g entry */
*offset = 0;
- ++*index;
- ++sg;
+ sg = sg_next(sg);
}
/* Transfer the data for all the pages in this
@@ -234,6 +234,7 @@ unsigned int usb_stor_access_xfer_buf(unsigned char *buffer,
sglen -= plen;
}
}
+ *sgptr = sg;
}
/* Return the amount actually transferred */
@@ -245,9 +246,10 @@ unsigned int usb_stor_access_xfer_buf(unsigned char *buffer,
void usb_stor_set_xfer_buf(unsigned char *buffer,
unsigned int buflen, struct scsi_cmnd *srb)
{
- unsigned int index = 0, offset = 0;
+ unsigned int offset = 0;
+ struct scatterlist *sg = NULL;
- usb_stor_access_xfer_buf(buffer, buflen, srb, &index, &offset,
+ usb_stor_access_xfer_buf(buffer, buflen, srb, &sg, &offset,
TO_XFER_BUF);
if (buflen < srb->request_bufflen)
srb->resid = srb->request_bufflen - buflen;