[PATCH 002 of 6] Introduce rq_for_each_segment replacing rq_for_each_bio

From: NeilBrown
Date: Thu Aug 16 2007 - 07:21:53 EST


Every usage of rq_for_each_bio wraps a usage of
bio_for_each_segment, so these can be combined into
rq_for_each_segment.

We define "struct req_iterator" to hold the 'bio' and 'index' that
are needed for the double iteration.

Signed-off-by: Neil Brown <neilb@xxxxxxx>

### Diffstat output
./Documentation/block/biodoc.txt | 22 +++++++++++-----------
./block/ll_rw_blk.c | 19 ++++++-------------
./drivers/block/floppy.c | 14 ++++----------
./drivers/block/lguest_blk.c | 10 ++++------
./drivers/block/nbd.c | 22 +++++++++-------------
./drivers/block/ps3disk.c | 29 +++++++++++++++--------------
./drivers/block/xen-blkfront.c | 7 ++-----
./drivers/ide/ide-floppy.c | 16 ++++++----------
./drivers/s390/block/dasd_diag.c | 11 +++--------
./drivers/s390/block/dasd_eckd.c | 15 ++++++---------
./drivers/s390/block/dasd_fba.c | 15 ++++++---------
./drivers/s390/char/tape_34xx.c | 15 +++++----------
./drivers/s390/char/tape_3590.c | 16 ++++++----------
./include/linux/blkdev.h | 15 ++++++++++++++-
14 files changed, 97 insertions(+), 129 deletions(-)

diff .prev/block/ll_rw_blk.c ./block/ll_rw_blk.c
--- .prev/block/ll_rw_blk.c 2007-08-16 17:43:27.000000000 +1000
+++ ./block/ll_rw_blk.c 2007-08-16 20:53:44.000000000 +1000
@@ -1233,8 +1233,7 @@ static void blk_recalc_rq_segments(struc
int seg_size;
int hw_seg_size;
int cluster;
- struct bio *bio;
- int i;
+ struct req_iterator iter;
int high, highprv = 1;
struct request_queue *q = rq->q;

@@ -1244,8 +1243,7 @@ static void blk_recalc_rq_segments(struc
cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER);
hw_seg_size = seg_size = 0;
phys_size = hw_size = nr_phys_segs = nr_hw_segs = 0;
- rq_for_each_bio(bio, rq)
- bio_for_each_segment(bv, bio, i) {
+ rq_for_each_segment(bv, rq, iter) {
/*
* the trick here is making sure that a high page is never
* considered part of another segment, since that might
@@ -1342,8 +1340,8 @@ int blk_rq_map_sg(struct request_queue *
struct scatterlist *sg)
{
struct bio_vec *bvec, *bvprv;
- struct bio *bio;
- int nsegs, i, cluster;
+ struct req_iterator iter;
+ int nsegs, cluster;

nsegs = 0;
cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER);
@@ -1352,11 +1350,7 @@ int blk_rq_map_sg(struct request_queue *
* for each bio in rq
*/
bvprv = NULL;
- rq_for_each_bio(bio, rq) {
- /*
- * for each segment in bio
- */
- bio_for_each_segment(bvec, bio, i) {
+ rq_for_each_segment(bvec, rq, iter) {
int nbytes = bvec->bv_len;

if (bvprv && cluster) {
@@ -1379,8 +1373,7 @@ new_segment:
nsegs++;
}
bvprv = bvec;
- } /* segments in bio */
- } /* bios in rq */
+ } /* segments in rq */

return nsegs;
}

diff .prev/Documentation/block/biodoc.txt ./Documentation/block/biodoc.txt
--- .prev/Documentation/block/biodoc.txt 2007-08-16 20:51:10.000000000 +1000
+++ ./Documentation/block/biodoc.txt 2007-08-16 20:52:51.000000000 +1000
@@ -477,9 +477,9 @@ With this multipage bio design:
the same bi_io_vec array, but with the index and size accordingly modified)
- A linked list of bios is used as before for unrelated merges (*) - this
avoids reallocs and makes independent completions easier to handle.
-- Code that traverses the req list needs to make a distinction between
- segments of a request (bio_for_each_segment) and the distinct completion
- units/bios (rq_for_each_bio).
+- Code that traverses the req list can find all the segments of a bio
+ by using rq_for_each_segment. This handles the fact that a request
+ has multiple bios, each of which can have multiple segments.
- Drivers which can't process a large bio in one shot can use the bi_idx
field to keep track of the next bio_vec entry to process.
(e.g a 1MB bio_vec needs to be handled in max 128kB chunks for IDE)
@@ -664,14 +664,14 @@ in lvm or md.

3.2.1 Traversing segments and completion units in a request

-The macros bio_for_each_segment() and rq_for_each_bio() should be used for
-traversing the bios in the request list (drivers should avoid directly
-trying to do it themselves). Using these helpers should also make it easier
-to cope with block changes in the future.
-
- rq_for_each_bio(bio, rq)
- bio_for_each_segment(bio_vec, bio, i)
- /* bio_vec is now current segment */
+The macro rq_for_each_segment() should be used for traversing the bios
+in the request list (drivers should avoid directly trying to do it
+themselves). Using these helpers should also make it easier to cope
+with block changes in the future.
+
+ struct req_iterator iter;
+ rq_for_each_segment(bio_vec, rq, iter)
+ /* bio_vec is now current segment */

I/O completion callbacks are per-bio rather than per-segment, so drivers
that traverse bio chains on completion need to keep that in mind. Drivers

diff .prev/drivers/block/floppy.c ./drivers/block/floppy.c
--- .prev/drivers/block/floppy.c 2007-08-16 17:18:38.000000000 +1000
+++ ./drivers/block/floppy.c 2007-08-16 17:55:58.000000000 +1000
@@ -2450,23 +2450,20 @@ static void rw_interrupt(void)
/* Compute maximal contiguous buffer size. */
static int buffer_chain_size(void)
{
- struct bio *bio;
struct bio_vec *bv;
int size;
- int i;
+ struct req_iterator iter;
char *base;

base = bio_data(current_req->bio);
size = 0;

- rq_for_each_bio(bio, current_req) {
- bio_for_each_segment(bv, bio, i) {
+ rq_for_each_segment(bv, current_req, iter) {
if (page_address(bv->bv_page) + bv->bv_offset !=
base + size)
break;

size += bv->bv_len;
- }
}

return size >> 9;
@@ -2493,11 +2490,10 @@ static void copy_buffer(int ssize, int m
{
int remaining; /* number of transferred 512-byte sectors */
struct bio_vec *bv;
- struct bio *bio;
char *buffer;
char *dma_buffer;
int size;
- int i;
+ struct req_iterator iter;

max_sector = transfer_size(ssize,
min(max_sector, max_sector_2),
@@ -2530,8 +2526,7 @@ static void copy_buffer(int ssize, int m

size = current_req->current_nr_sectors << 9;

- rq_for_each_bio(bio, current_req) {
- bio_for_each_segment(bv, bio, i) {
+ rq_for_each_segment(bv, current_req, iter) {
if (!remaining)
break;

@@ -2566,7 +2561,6 @@ static void copy_buffer(int ssize, int m

remaining -= size;
dma_buffer += size;
- }
}
#ifdef FLOPPY_SANITY_CHECK
if (remaining) {

diff .prev/drivers/block/lguest_blk.c ./drivers/block/lguest_blk.c
--- .prev/drivers/block/lguest_blk.c 2007-08-16 17:18:37.000000000 +1000
+++ ./drivers/block/lguest_blk.c 2007-08-16 17:58:14.000000000 +1000
@@ -142,12 +142,11 @@ static irqreturn_t lgb_irq(int irq, void
* return the total length. */
static unsigned int req_to_dma(struct request *req, struct lguest_dma *dma)
{
- unsigned int i = 0, idx, len = 0;
- struct bio *bio;
+ unsigned int i = 0, len = 0;
+ struct req_iterator iter;
+ struct bio_vec *bvec;

- rq_for_each_bio(bio, req) {
- struct bio_vec *bvec;
- bio_for_each_segment(bvec, bio, idx) {
+ rq_for_each_segment(bvec, req, iter) {
/* We told the block layer not to give us too many. */
BUG_ON(i == LGUEST_MAX_DMA_SECTIONS);
/* If we had a zero-length segment, it would look like
@@ -160,7 +159,6 @@ static unsigned int req_to_dma(struct re
dma->len[i] = bvec->bv_len;
len += bvec->bv_len;
i++;
- }
}
/* If the array isn't full, we mark the end with a 0 length */
if (i < LGUEST_MAX_DMA_SECTIONS)

diff .prev/drivers/block/nbd.c ./drivers/block/nbd.c
--- .prev/drivers/block/nbd.c 2007-08-16 17:18:37.000000000 +1000
+++ ./drivers/block/nbd.c 2007-08-16 20:31:41.000000000 +1000
@@ -180,7 +180,7 @@ static inline int sock_send_bvec(struct

static int nbd_send_req(struct nbd_device *lo, struct request *req)
{
- int result, i, flags;
+ int result, flags;
struct nbd_request request;
unsigned long size = req->nr_sectors << 9;
struct socket *sock = lo->sock;
@@ -205,16 +205,15 @@ static int nbd_send_req(struct nbd_devic
}

if (nbd_cmd(req) == NBD_CMD_WRITE) {
- struct bio *bio;
+ struct req_iterator iter;
+ struct bio_vec *bvec;
/*
* we are really probing at internals to determine
* whether to set MSG_MORE or not...
*/
- rq_for_each_bio(bio, req) {
- struct bio_vec *bvec;
- bio_for_each_segment(bvec, bio, i) {
+ rq_for_each_segment(bvec, req, iter) {
flags = 0;
- if ((i < (bio->bi_vcnt - 1)) || bio->bi_next)
+ if (!rq_iter_last(req, iter))
flags = MSG_MORE;
dprintk(DBG_TX, "%s: request %p: sending %d bytes data\n",
lo->disk->disk_name, req,
@@ -226,7 +225,6 @@ static int nbd_send_req(struct nbd_devic
result);
goto error_out;
}
- }
}
}
return 0;
@@ -317,11 +315,10 @@ static struct request *nbd_read_stat(str
dprintk(DBG_RX, "%s: request %p: got reply\n",
lo->disk->disk_name, req);
if (nbd_cmd(req) == NBD_CMD_READ) {
- int i;
- struct bio *bio;
- rq_for_each_bio(bio, req) {
- struct bio_vec *bvec;
- bio_for_each_segment(bvec, bio, i) {
+ struct req_iterator iter;
+ struct bio_vec *bvec;
+
+ rq_for_each_segment(bvec, req, iter) {
result = sock_recv_bvec(sock, bvec);
if (result <= 0) {
printk(KERN_ERR "%s: Receive data failed (result %d)\n",
@@ -332,7 +329,6 @@ static struct request *nbd_read_stat(str
}
dprintk(DBG_RX, "%s: request %p: got %d bytes data\n",
lo->disk->disk_name, req, bvec->bv_len);
- }
}
}
return req;

diff .prev/drivers/block/ps3disk.c ./drivers/block/ps3disk.c
--- .prev/drivers/block/ps3disk.c 2007-08-16 20:37:26.000000000 +1000
+++ ./drivers/block/ps3disk.c 2007-08-16 20:50:07.000000000 +1000
@@ -91,30 +91,30 @@ static void ps3disk_scatter_gather(struc
struct request *req, int gather)
{
unsigned int offset = 0;
- struct bio *bio;
- sector_t sector;
+ struct req_iterator iter;
struct bio_vec *bvec;
- unsigned int i = 0, j;
+ unsigned int i = 0;
size_t size;
void *buf;

- rq_for_each_bio(bio, req) {
- sector = bio->bi_sector;
+ rq_for_each_segment(bvec, req, iter) {
+ unsigned long flags;
dev_dbg(&dev->sbd.core,
"%s:%u: bio %u: %u segs %u sectors from %lu\n",
- __func__, __LINE__, i, bio_segments(bio),
- bio_sectors(bio), sector);
- bio_for_each_segment(bvec, bio, j) {
+ __func__, __LINE__, i, bio_segments(iter.bio),
+ bio_sectors(iter.bio),
+ (unsigned long)iter.bio->bi_sector);
+
size = bvec->bv_len;
- buf = __bio_kmap_atomic(bio, j, KM_IRQ0);
+ buf = bvec_kmap_irq(bvec, flags);
if (gather)
memcpy(dev->bounce_buf+offset, buf, size);
else
memcpy(buf, dev->bounce_buf+offset, size);
offset += size;
flush_kernel_dcache_page(bio_iovec_idx(bio, j)->bv_page);
- __bio_kunmap_atomic(bio, KM_IRQ0);
- }
+ bio_kunmap_bvec(bvec, flags);
+
i++;
}
}
@@ -130,12 +130,13 @@ static int ps3disk_submit_request_sg(str

#ifdef DEBUG
unsigned int n = 0;
- struct bio *bio;
+ struct bio_vec *bv;
+ struct req_iterator iter;

- rq_for_each_bio(bio, req)
+ rq_for_each_segment(bv, req, iter)
n++;
dev_dbg(&dev->sbd.core,
- "%s:%u: %s req has %u bios for %lu sectors %lu hard sectors\n",
+ "%s:%u: %s req has %u bvecs for %lu sectors %lu hard sectors\n",
__func__, __LINE__, op, n, req->nr_sectors,
req->hard_nr_sectors);
#endif

diff .prev/drivers/block/xen-blkfront.c ./drivers/block/xen-blkfront.c
--- .prev/drivers/block/xen-blkfront.c 2007-08-16 17:18:37.000000000 +1000
+++ ./drivers/block/xen-blkfront.c 2007-08-16 18:03:12.000000000 +1000
@@ -150,9 +150,8 @@ static int blkif_queue_request(struct re
struct blkfront_info *info = req->rq_disk->private_data;
unsigned long buffer_mfn;
struct blkif_request *ring_req;
- struct bio *bio;
+ struct req_iterator iter;
struct bio_vec *bvec;
- int idx;
unsigned long id;
unsigned int fsect, lsect;
int ref;
@@ -186,8 +185,7 @@ static int blkif_queue_request(struct re
ring_req->operation = BLKIF_OP_WRITE_BARRIER;

ring_req->nr_segments = 0;
- rq_for_each_bio (bio, req) {
- bio_for_each_segment (bvec, bio, idx) {
+ rq_for_each_segment(bvec, req, iter) {
BUG_ON(ring_req->nr_segments
== BLKIF_MAX_SEGMENTS_PER_REQUEST);
buffer_mfn = pfn_to_mfn(page_to_pfn(bvec->bv_page));
@@ -213,7 +211,6 @@ static int blkif_queue_request(struct re
.last_sect = lsect };

ring_req->nr_segments++;
- }
}

info->ring.req_prod_pvt++;

diff .prev/drivers/ide/ide-floppy.c ./drivers/ide/ide-floppy.c
--- .prev/drivers/ide/ide-floppy.c 2007-08-16 17:18:37.000000000 +1000
+++ ./drivers/ide/ide-floppy.c 2007-08-16 18:04:55.000000000 +1000
@@ -606,13 +606,12 @@ static void idefloppy_input_buffers (ide
{
struct request *rq = pc->rq;
struct bio_vec *bvec;
- struct bio *bio;
+ struct req_iterator iter;
unsigned long flags;
char *data;
- int count, i, done = 0;
+ int count, done = 0;

- rq_for_each_bio(bio, rq) {
- bio_for_each_segment(bvec, bio, i) {
+ rq_for_each_segment(bvec, rq, iter) {
if (!bcount)
break;

@@ -625,7 +624,6 @@ static void idefloppy_input_buffers (ide
bcount -= count;
pc->b_count += count;
done += count;
- }
}

idefloppy_do_end_request(drive, 1, done >> 9);
@@ -639,14 +637,13 @@ static void idefloppy_input_buffers (ide
static void idefloppy_output_buffers (ide_drive_t *drive, idefloppy_pc_t *pc, unsigned int bcount)
{
struct request *rq = pc->rq;
- struct bio *bio;
+ struct req_iterator iter;
struct bio_vec *bvec;
unsigned long flags;
- int count, i, done = 0;
+ int count, done = 0;
char *data;

- rq_for_each_bio(bio, rq) {
- bio_for_each_segment(bvec, bio, i) {
+ rq_for_each_segment(bvec, rq, iter) {
if (!bcount)
break;

@@ -659,7 +656,6 @@ static void idefloppy_output_buffers (id
bcount -= count;
pc->b_count += count;
done += count;
- }
}

idefloppy_do_end_request(drive, 1, done >> 9);

diff .prev/drivers/s390/block/dasd_diag.c ./drivers/s390/block/dasd_diag.c
--- .prev/drivers/s390/block/dasd_diag.c 2007-08-16 17:18:37.000000000 +1000
+++ ./drivers/s390/block/dasd_diag.c 2007-08-16 18:06:21.000000000 +1000
@@ -471,14 +471,13 @@ dasd_diag_build_cp(struct dasd_device *
struct dasd_ccw_req *cqr;
struct dasd_diag_req *dreq;
struct dasd_diag_bio *dbio;
- struct bio *bio;
+ struct req_iterator iter;
struct bio_vec *bv;
char *dst;
unsigned int count, datasize;
sector_t recid, first_rec, last_rec;
unsigned int blksize, off;
unsigned char rw_cmd;
- int i;

if (rq_data_dir(req) == READ)
rw_cmd = MDSK_READ_REQ;
@@ -492,13 +491,11 @@ dasd_diag_build_cp(struct dasd_device *
last_rec = (req->sector + req->nr_sectors - 1) >> device->s2b_shift;
/* Check struct bio and count the number of blocks for the request. */
count = 0;
- rq_for_each_bio(bio, req) {
- bio_for_each_segment(bv, bio, i) {
+ rq_for_each_segment(bv, req, iter) {
if (bv->bv_len & (blksize - 1))
/* Fba can only do full blocks. */
return ERR_PTR(-EINVAL);
count += bv->bv_len >> (device->s2b_shift + 9);
- }
}
/* Paranoia. */
if (count != last_rec - first_rec + 1)
@@ -515,8 +512,7 @@ dasd_diag_build_cp(struct dasd_device *
dreq->block_count = count;
dbio = dreq->bio;
recid = first_rec;
- rq_for_each_bio(bio, req) {
- bio_for_each_segment(bv, bio, i) {
+ rq_for_each_segment(bv, req, iter) {
dst = page_address(bv->bv_page) + bv->bv_offset;
for (off = 0; off < bv->bv_len; off += blksize) {
memset(dbio, 0, sizeof (struct dasd_diag_bio));
@@ -527,7 +523,6 @@ dasd_diag_build_cp(struct dasd_device *
dst += blksize;
recid++;
}
- }
}
cqr->retries = DIAG_MAX_RETRIES;
cqr->buildclk = get_clock();

diff .prev/drivers/s390/block/dasd_eckd.c ./drivers/s390/block/dasd_eckd.c
--- .prev/drivers/s390/block/dasd_eckd.c 2007-08-16 17:18:37.000000000 +1000
+++ ./drivers/s390/block/dasd_eckd.c 2007-08-16 18:07:59.000000000 +1000
@@ -1176,7 +1176,7 @@ dasd_eckd_build_cp(struct dasd_device *
struct LO_eckd_data *LO_data;
struct dasd_ccw_req *cqr;
struct ccw1 *ccw;
- struct bio *bio;
+ struct req_iterator iter
struct bio_vec *bv;
char *dst;
unsigned int blksize, blk_per_trk, off;
@@ -1185,7 +1185,6 @@ dasd_eckd_build_cp(struct dasd_device *
sector_t first_trk, last_trk;
unsigned int first_offs, last_offs;
unsigned char cmd, rcmd;
- int i;

private = (struct dasd_eckd_private *) device->private;
if (rq_data_dir(req) == READ)
@@ -1206,8 +1205,7 @@ dasd_eckd_build_cp(struct dasd_device *
/* Check struct bio and count the number of blocks for the request. */
count = 0;
cidaw = 0;
- rq_for_each_bio(bio, req) {
- bio_for_each_segment(bv, bio, i) {
+ rq_for_each_segment(bv, req, iter) {
if (bv->bv_len & (blksize - 1))
/* Eckd can only do full blocks. */
return ERR_PTR(-EINVAL);
@@ -1217,7 +1215,6 @@ dasd_eckd_build_cp(struct dasd_device *
bv->bv_len))
cidaw += bv->bv_len >> (device->s2b_shift + 9);
#endif
- }
}
/* Paranoia. */
if (count != last_rec - first_rec + 1)
@@ -1257,7 +1254,7 @@ dasd_eckd_build_cp(struct dasd_device *
locate_record(ccw++, LO_data++, first_trk, first_offs + 1,
last_rec - recid + 1, cmd, device, blksize);
}
- rq_for_each_bio(bio, req) bio_for_each_segment(bv, bio, i) {
+ rq_for_each_segment(bv, req, iter) {
dst = page_address(bv->bv_page) + bv->bv_offset;
if (dasd_page_cache) {
char *copy = kmem_cache_alloc(dasd_page_cache,
@@ -1328,12 +1325,12 @@ dasd_eckd_free_cp(struct dasd_ccw_req *c
{
struct dasd_eckd_private *private;
struct ccw1 *ccw;
- struct bio *bio;
+ struct req_iterator iter;
struct bio_vec *bv;
char *dst, *cda;
unsigned int blksize, blk_per_trk, off;
sector_t recid;
- int i, status;
+ int status;

if (!dasd_page_cache)
goto out;
@@ -1346,7 +1343,7 @@ dasd_eckd_free_cp(struct dasd_ccw_req *c
ccw++;
if (private->uses_cdl == 0 || recid > 2*blk_per_trk)
ccw++;
- rq_for_each_bio(bio, req) bio_for_each_segment(bv, bio, i) {
+ rq_for_each_segment(bv, req, iter) {
dst = page_address(bv->bv_page) + bv->bv_offset;
for (off = 0; off < bv->bv_len; off += blksize) {
/* Skip locate record. */

diff .prev/drivers/s390/block/dasd_fba.c ./drivers/s390/block/dasd_fba.c
--- .prev/drivers/s390/block/dasd_fba.c 2007-08-16 17:18:37.000000000 +1000
+++ ./drivers/s390/block/dasd_fba.c 2007-08-16 18:09:43.000000000 +1000
@@ -234,14 +234,13 @@ dasd_fba_build_cp(struct dasd_device * d
struct LO_fba_data *LO_data;
struct dasd_ccw_req *cqr;
struct ccw1 *ccw;
- struct bio *bio;
+ struct req_iterator iter;
struct bio_vec *bv;
char *dst;
int count, cidaw, cplength, datasize;
sector_t recid, first_rec, last_rec;
unsigned int blksize, off;
unsigned char cmd;
- int i;

private = (struct dasd_fba_private *) device->private;
if (rq_data_dir(req) == READ) {
@@ -257,8 +256,7 @@ dasd_fba_build_cp(struct dasd_device * d
/* Check struct bio and count the number of blocks for the request. */
count = 0;
cidaw = 0;
- rq_for_each_bio(bio, req) {
- bio_for_each_segment(bv, bio, i) {
+ rq_for_each_segment(bv, req, iter) {
if (bv->bv_len & (blksize - 1))
/* Fba can only do full blocks. */
return ERR_PTR(-EINVAL);
@@ -268,7 +266,6 @@ dasd_fba_build_cp(struct dasd_device * d
bv->bv_len))
cidaw += bv->bv_len / blksize;
#endif
- }
}
/* Paranoia. */
if (count != last_rec - first_rec + 1)
@@ -304,7 +301,7 @@ dasd_fba_build_cp(struct dasd_device * d
locate_record(ccw++, LO_data++, rq_data_dir(req), 0, count);
}
recid = first_rec;
- rq_for_each_bio(bio, req) bio_for_each_segment(bv, bio, i) {
+ rq_for_each_segment(bv, req, iter) {
dst = page_address(bv->bv_page) + bv->bv_offset;
if (dasd_page_cache) {
char *copy = kmem_cache_alloc(dasd_page_cache,
@@ -359,11 +356,11 @@ dasd_fba_free_cp(struct dasd_ccw_req *cq
{
struct dasd_fba_private *private;
struct ccw1 *ccw;
- struct bio *bio;
+ struct req_iterator iter;
struct bio_vec *bv;
char *dst, *cda;
unsigned int blksize, off;
- int i, status;
+ int status;

if (!dasd_page_cache)
goto out;
@@ -374,7 +371,7 @@ dasd_fba_free_cp(struct dasd_ccw_req *cq
ccw++;
if (private->rdc_data.mode.bits.data_chain != 0)
ccw++;
- rq_for_each_bio(bio, req) bio_for_each_segment(bv, bio, i) {
+ rq_for_each_segment(bv, req, iter) {
dst = page_address(bv->bv_page) + bv->bv_offset;
for (off = 0; off < bv->bv_len; off += blksize) {
/* Skip locate record. */

diff .prev/drivers/s390/char/tape_34xx.c ./drivers/s390/char/tape_34xx.c
--- .prev/drivers/s390/char/tape_34xx.c 2007-08-16 17:18:37.000000000 +1000
+++ ./drivers/s390/char/tape_34xx.c 2007-08-16 18:10:50.000000000 +1000
@@ -1134,21 +1134,18 @@ tape_34xx_bread(struct tape_device *devi
{
struct tape_request *request;
struct ccw1 *ccw;
- int count = 0, i;
+ int count = 0;
unsigned off;
char *dst;
struct bio_vec *bv;
- struct bio *bio;
+ struct req_iterator iter;
struct tape_34xx_block_id * start_block;

DBF_EVENT(6, "xBREDid:");

/* Count the number of blocks for the request. */
- rq_for_each_bio(bio, req) {
- bio_for_each_segment(bv, bio, i) {
- count += bv->bv_len >> (TAPEBLOCK_HSEC_S2B + 9);
- }
- }
+ rq_for_each_segment(bv, req, iter)
+ count += bv->bv_len >> (TAPEBLOCK_HSEC_S2B + 9);

/* Allocate the ccw request. */
request = tape_alloc_request(3+count+1, 8);
@@ -1175,8 +1172,7 @@ tape_34xx_bread(struct tape_device *devi
ccw = tape_ccw_cc(ccw, NOP, 0, NULL);
ccw = tape_ccw_cc(ccw, NOP, 0, NULL);

- rq_for_each_bio(bio, req) {
- bio_for_each_segment(bv, bio, i) {
+ rq_for_each_segment(bv, req, iter) {
dst = kmap(bv->bv_page) + bv->bv_offset;
for (off = 0; off < bv->bv_len;
off += TAPEBLOCK_HSEC_SIZE) {
@@ -1187,7 +1183,6 @@ tape_34xx_bread(struct tape_device *devi
ccw++;
dst += TAPEBLOCK_HSEC_SIZE;
}
- }
}

ccw = tape_ccw_end(ccw, NOP, 0, NULL);

diff .prev/drivers/s390/char/tape_3590.c ./drivers/s390/char/tape_3590.c
--- .prev/drivers/s390/char/tape_3590.c 2007-08-16 17:18:37.000000000 +1000
+++ ./drivers/s390/char/tape_3590.c 2007-08-16 20:30:31.000000000 +1000
@@ -623,21 +623,19 @@ tape_3590_bread(struct tape_device *devi
{
struct tape_request *request;
struct ccw1 *ccw;
- int count = 0, start_block, i;
+ int count = 0, start_block;
unsigned off;
char *dst;
struct bio_vec *bv;
- struct bio *bio;
+ struct req_iterator iter;

DBF_EVENT(6, "xBREDid:");
start_block = req->sector >> TAPEBLOCK_HSEC_S2B;
DBF_EVENT(6, "start_block = %i\n", start_block);

- rq_for_each_bio(bio, req) {
- bio_for_each_segment(bv, bio, i) {
- count += bv->bv_len >> (TAPEBLOCK_HSEC_S2B + 9);
- }
- }
+ rq_for_each_segment(bv, req, iter)
+ count += bv->bv_len >> (TAPEBLOCK_HSEC_S2B + 9);
+
request = tape_alloc_request(2 + count + 1, 4);
if (IS_ERR(request))
return request;
@@ -653,8 +651,7 @@ tape_3590_bread(struct tape_device *devi
*/
ccw = tape_ccw_cc(ccw, NOP, 0, NULL);

- rq_for_each_bio(bio, req) {
- bio_for_each_segment(bv, bio, i) {
+ rq_for_each_segment(bv, req, iter) {
dst = page_address(bv->bv_page) + bv->bv_offset;
for (off = 0; off < bv->bv_len;
off += TAPEBLOCK_HSEC_SIZE) {
@@ -667,7 +664,6 @@ tape_3590_bread(struct tape_device *devi
}
if (off > bv->bv_len)
BUG();
- }
}
ccw = tape_ccw_end(ccw, NOP, 0, NULL);
DBF_EVENT(6, "xBREDccwg\n");

diff .prev/include/linux/blkdev.h ./include/linux/blkdev.h
--- .prev/include/linux/blkdev.h 2007-08-16 17:39:13.000000000 +1000
+++ ./include/linux/blkdev.h 2007-08-16 20:54:26.000000000 +1000
@@ -637,10 +637,23 @@ static inline void blk_queue_bounce(stru
}
#endif /* CONFIG_MMU */

-#define rq_for_each_bio(_bio, rq) \
+struct req_iterator {
+ int i;
+ struct bio *bio;
+};
+
+/* This should not be used directly - use rq_for_each_segment */
+#define __rq_for_each_bio(_bio, rq) \
if ((rq->bio)) \
for (_bio = (rq)->bio; _bio; _bio = _bio->bi_next)

+#define rq_for_each_segment(bvl, _rq, _iter) \
+ __rq_for_each_bio(_iter.bio, _rq) \
+ bio_for_each_segment(bvl, _iter.bio, _iter.i)
+
+#define rq_iter_last(rq, _iter) \
+ (_iter.bio->bi_next == NULL && _iter.i == _iter.bio->bi_vcnt-1)
+
extern int blk_register_queue(struct gendisk *disk);
extern void blk_unregister_queue(struct gendisk *disk);
extern void register_disk(struct gendisk *dev);
-
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