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Subject[PATCH 017 of 35] 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>

### Diffstat output
./drivers/block/umem.c | 38 +++++++++++++++++++++++++-------------
1 file changed, 25 insertions(+), 13 deletions(-)
diff .prev/drivers/block/umem.c ./drivers/block/umem.c
--- .prev/drivers/block/umem.c 2007-07-31 11:20:51.000000000 +1000
+++ ./drivers/block/umem.c 2007-07-31 11:21:02.000000000 +1000
@@ -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 d
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 reques
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;
-
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