Fix various abuse of bio fields in umem.c

umem.c:
  advances bi_idx and bi_sector to track where it is up to.
   But it is only ever doing this on one bio, so the updated
   fields can easily be kept elsewhere (current_*).
  updates bi_size, but never uses the updated values, so
   this isn't needed.
  reuses bi_phys_segments to count how many iovecs have been
   completely.  As the completion happens sequentiually, we
   can store this information outside the bio too.

Signed-off-by: Neil Brown <neilb@suse.de>

diff .prev/drivers/block/umem.c ./drivers/block/umem.c
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 25 insertions, 13 deletions

diff --git a/drivers/block/umem.c b/drivers/block/umem.c
index 6b7c02d6360d..c378e285d708 100644
--- a/drivers/block/umem.c
+++ b/drivers/block/umem.c
@@ -113,6 +113,8 @@ struct cardinfo {
                                     * have been written
                                     */
         struct bio      *bio, *currentbio, **biotail;
+        int             current_idx;
+        sector_t        current_sector;
 
         struct request_queue *queue;
 
@@ -121,6 +123,7 @@ struct cardinfo {
                 struct mm_dma_desc      *desc;
                 int                     cnt, headcnt;
                 struct bio              *bio, **biotail;
+                int                     idx;
         } mm_pages[2];
 #define DESC_PER_PAGE ((PAGE_SIZE*2)/sizeof(struct mm_dma_desc))
 
@@ -380,12 +383,16 @@ static int add_bio(struct cardinfo *card)
         dma_addr_t dma_handle;
         int offset;
         struct bio *bio;
+        struct bio_vec *vec;
+        int idx;
         int rw;
         int len;
 
         bio = card->currentbio;
         if (!bio && card->bio) {
                 card->currentbio = card->bio;
+                card->current_idx = card->bio->bi_idx;
+                card->current_sector = card->bio->bi_sector;
                 card->bio = card->bio->bi_next;
                 if (card->bio == NULL)
                         card->biotail = &card->bio;
@@ -394,15 +401,17 @@ static int add_bio(struct cardinfo *card)
         }
         if (!bio)
                 return 0;
+        idx = card->current_idx;
 
         rw = bio_rw(bio);
         if (card->mm_pages[card->Ready].cnt >= DESC_PER_PAGE)
                 return 0;
 
-        len = bio_iovec(bio)->bv_len;
-        dma_handle = pci_map_page(card->dev, 
-                                  bio_page(bio),
-                                  bio_offset(bio),
+        vec = bio_iovec_idx(bio, idx);
+        len = vec->bv_len;
+        dma_handle = pci_map_page(card->dev,
+                                  vec->bv_page,
+                                  vec->bv_offset,
                                   len,
                                   (rw==READ) ?
                                   PCI_DMA_FROMDEVICE : PCI_DMA_TODEVICE);
@@ -410,6 +419,8 @@ static int add_bio(struct cardinfo *card)
         p = &card->mm_pages[card->Ready];
         desc = &p->desc[p->cnt];
         p->cnt++;
+        if (p->bio == NULL)
+                p->idx = idx;
         if ((p->biotail) != &bio->bi_next) {
                 *(p->biotail) = bio;
                 p->biotail = &(bio->bi_next);
@@ -419,7 +430,7 @@ static int add_bio(struct cardinfo *card)
         desc->data_dma_handle = dma_handle;
 
         desc->pci_addr = cpu_to_le64((u64)desc->data_dma_handle);
-        desc->local_addr= cpu_to_le64(bio->bi_sector << 9);
+        desc->local_addr = cpu_to_le64(card->current_sector << 9);
         desc->transfer_size = cpu_to_le32(len);
         offset = ( ((char*)&desc->sem_control_bits) - ((char*)p->desc));
         desc->sem_addr = cpu_to_le64((u64)(p->page_dma+offset));
@@ -435,10 +446,10 @@ static int add_bio(struct cardinfo *card)
                 desc->control_bits |= cpu_to_le32(DMASCR_TRANSFER_READ);
         desc->sem_control_bits = desc->control_bits;
 
-        bio->bi_sector += (len>>9);
-        bio->bi_size -= len;
-        bio->bi_idx++;
-        if (bio->bi_idx >= bio->bi_vcnt) 
+        card->current_sector += (len >> 9);
+        idx++;
+        card->current_idx = idx;
+        if (idx >= bio->bi_vcnt)
                 card->currentbio = NULL;
 
         return 1;
@@ -474,10 +485,12 @@ static void process_page(unsigned long data)
                         last=1; 
                 }
                 page->headcnt++;
-                idx = bio->bi_phys_segments;
-                bio->bi_phys_segments++;
-                if (bio->bi_phys_segments >= bio->bi_vcnt)
+                idx = page->idx;
+                page->idx++;
+                if (page->idx >= bio->bi_vcnt) {
                         page->bio = bio->bi_next;
+                        page->idx = page->bio->bi_idx;
+                }
 
                 pci_unmap_page(card->dev, desc->data_dma_handle, 
                                bio_iovec_idx(bio,idx)->bv_len,
@@ -547,7 +560,6 @@ static int mm_make_request(struct request_queue *q, struct bio *bio)
         pr_debug("mm_make_request %llu %u\n",
                  (unsigned long long)bio->bi_sector, bio->bi_size);
 
-        bio->bi_phys_segments = bio->bi_idx; /* count of completed segments*/
         spin_lock_irq(&card->lock);
         *card->biotail = bio;
         bio->bi_next = NULL;