scsi: storvsc: Don't assume that the scatterlist is not chained

The current code assumes that the scatterlists presented are not chained.
Fix the code to not make this assumption.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: Long Li <longli@microsoft.com>
Signed-off-by: James Bottomley <JBottomley@Odin.com>

1 files changed, 57 insertions, 42 deletions

diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
index f8e4dd925a9d..4156e297ea64 100644
--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -626,19 +626,6 @@ cleanup:
         return NULL;
 }
 
-/* Disgusting wrapper functions */
-static inline unsigned long sg_kmap_atomic(struct scatterlist *sgl, int idx)
-{
-        void *addr = kmap_atomic(sg_page(sgl + idx));
-        return (unsigned long)addr;
-}
-
-static inline void sg_kunmap_atomic(unsigned long addr)
-{
-        kunmap_atomic((void *)addr);
-}
-
-
 /* Assume the original sgl has enough room */
 static unsigned int copy_from_bounce_buffer(struct scatterlist *orig_sgl,
                                             struct scatterlist *bounce_sgl,
@@ -653,32 +640,38 @@ static unsigned int copy_from_bounce_buffer(struct scatterlist *orig_sgl,
         unsigned long bounce_addr = 0;
         unsigned long dest_addr = 0;
         unsigned long flags;
+        struct scatterlist *cur_dest_sgl;
+        struct scatterlist *cur_src_sgl;
 
         local_irq_save(flags);
-
+        cur_dest_sgl = orig_sgl;
+        cur_src_sgl = bounce_sgl;
         for (i = 0; i < orig_sgl_count; i++) {
-                dest_addr = sg_kmap_atomic(orig_sgl,i) + orig_sgl[i].offset;
+                dest_addr = (unsigned long)
+                                kmap_atomic(sg_page(cur_dest_sgl)) +
+                                cur_dest_sgl->offset;
                 dest = dest_addr;
-                destlen = orig_sgl[i].length;
+                destlen = cur_dest_sgl->length;
 
                 if (bounce_addr == 0)
-                        bounce_addr = sg_kmap_atomic(bounce_sgl,j);
+                        bounce_addr = (unsigned long)kmap_atomic(
+                                                        sg_page(cur_src_sgl));
 
                 while (destlen) {
-                        src = bounce_addr + bounce_sgl[j].offset;
-                        srclen = bounce_sgl[j].length - bounce_sgl[j].offset;
+                        src = bounce_addr + cur_src_sgl->offset;
+                        srclen = cur_src_sgl->length - cur_src_sgl->offset;
 
                         copylen = min(srclen, destlen);
                         memcpy((void *)dest, (void *)src, copylen);
 
                         total_copied += copylen;
-                        bounce_sgl[j].offset += copylen;
+                        cur_src_sgl->offset += copylen;
                         destlen -= copylen;
                         dest += copylen;
 
-                        if (bounce_sgl[j].offset == bounce_sgl[j].length) {
+                        if (cur_src_sgl->offset == cur_src_sgl->length) {
                                 /* full */
-                                sg_kunmap_atomic(bounce_addr);
+                                kunmap_atomic((void *)bounce_addr);
                                 j++;
 
                                 /*
@@ -692,21 +685,27 @@ static unsigned int copy_from_bounce_buffer(struct scatterlist *orig_sgl,
                                         /*
                                          * We are done; cleanup and return.
                                          */
-                                        sg_kunmap_atomic(dest_addr - orig_sgl[i].offset);
+                                        kunmap_atomic((void *)(dest_addr -
+                                                cur_dest_sgl->offset));
                                         local_irq_restore(flags);
                                         return total_copied;
                                 }
 
                                 /* if we need to use another bounce buffer */
-                                if (destlen || i != orig_sgl_count - 1)
-                                        bounce_addr = sg_kmap_atomic(bounce_sgl,j);
+                                if (destlen || i != orig_sgl_count - 1) {
+                                        cur_src_sgl = sg_next(cur_src_sgl);
+                                        bounce_addr = (unsigned long)
+                                                        kmap_atomic(
+                                                        sg_page(cur_src_sgl));
+                                }
                         } else if (destlen == 0 && i == orig_sgl_count - 1) {
                                 /* unmap the last bounce that is < PAGE_SIZE */
-                                sg_kunmap_atomic(bounce_addr);
+                                kunmap_atomic((void *)bounce_addr);
                         }
                 }
 
-                sg_kunmap_atomic(dest_addr - orig_sgl[i].offset);
+                kunmap_atomic((void *)(dest_addr - cur_dest_sgl->offset));
+                cur_dest_sgl = sg_next(cur_dest_sgl);
         }
 
         local_irq_restore(flags);
@@ -727,48 +726,61 @@ static unsigned int copy_to_bounce_buffer(struct scatterlist *orig_sgl,
         unsigned long bounce_addr = 0;
         unsigned long src_addr = 0;
         unsigned long flags;
+        struct scatterlist *cur_src_sgl;
+        struct scatterlist *cur_dest_sgl;
 
         local_irq_save(flags);
 
+        cur_src_sgl = orig_sgl;
+        cur_dest_sgl = bounce_sgl;
+
         for (i = 0; i < orig_sgl_count; i++) {
-                src_addr = sg_kmap_atomic(orig_sgl,i) + orig_sgl[i].offset;
+                src_addr = (unsigned long)
+                                kmap_atomic(sg_page(cur_src_sgl)) +
+                                cur_src_sgl->offset;
                 src = src_addr;
-                srclen = orig_sgl[i].length;
+                srclen = cur_src_sgl->length;
 
                 if (bounce_addr == 0)
-                        bounce_addr = sg_kmap_atomic(bounce_sgl,j);
+                        bounce_addr = (unsigned long)
+                                        kmap_atomic(sg_page(cur_dest_sgl));
 
                 while (srclen) {
                         /* assume bounce offset always == 0 */
-                        dest = bounce_addr + bounce_sgl[j].length;
-                        destlen = PAGE_SIZE - bounce_sgl[j].length;
+                        dest = bounce_addr + cur_dest_sgl->length;
+                        destlen = PAGE_SIZE - cur_dest_sgl->length;
 
                         copylen = min(srclen, destlen);
                         memcpy((void *)dest, (void *)src, copylen);
 
                         total_copied += copylen;
-                        bounce_sgl[j].length += copylen;
+                        cur_dest_sgl->length += copylen;
                         srclen -= copylen;
                         src += copylen;
 
-                        if (bounce_sgl[j].length == PAGE_SIZE) {
+                        if (cur_dest_sgl->length == PAGE_SIZE) {
                                 /* full..move to next entry */
-                                sg_kunmap_atomic(bounce_addr);
+                                kunmap_atomic((void *)bounce_addr);
                                 bounce_addr = 0;
                                 j++;
                         }
 
                         /* if we need to use another bounce buffer */
-                        if (srclen && bounce_addr == 0)
-                                bounce_addr = sg_kmap_atomic(bounce_sgl, j);
+                        if (srclen && bounce_addr == 0) {
+                                cur_dest_sgl = sg_next(cur_dest_sgl);
+                                bounce_addr = (unsigned long)
+                                                kmap_atomic(
+                                                sg_page(cur_dest_sgl));
+                        }
 
                 }
 
-                sg_kunmap_atomic(src_addr - orig_sgl[i].offset);
+                kunmap_atomic((void *)(src_addr - cur_src_sgl->offset));
+                cur_src_sgl = sg_next(cur_src_sgl);
         }
 
         if (bounce_addr)
-                sg_kunmap_atomic(bounce_addr);
+                kunmap_atomic((void *)bounce_addr);
 
         local_irq_restore(flags);
 
@@ -1536,6 +1548,7 @@ static int storvsc_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scmnd)
         struct scatterlist *sgl;
         unsigned int sg_count = 0;
         struct vmscsi_request *vm_srb;
+        struct scatterlist *cur_sgl;
 
         if (vmstor_current_major <= VMSTOR_WIN8_MAJOR) {
                 /*
@@ -1617,10 +1630,12 @@ static int storvsc_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scmnd)
                 }
 
                 cmd_request->data_buffer.offset = sgl[0].offset;
-
-                for (i = 0; i < sg_count; i++)
+                cur_sgl = sgl;
+                for (i = 0; i < sg_count; i++) {
                         cmd_request->data_buffer.pfn_array[i] =
-                                page_to_pfn(sg_page((&sgl[i])));
+                                page_to_pfn(sg_page((cur_sgl)));
+                        cur_sgl = sg_next(cur_sgl);
+                }
 
         } else if (scsi_sglist(scmnd)) {
                 cmd_request->data_buffer.offset =