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SubjectRe: [PATCH] Bio Traversal Changes (Patch 1/4: biotr8-blk.diff)
This patch has the core changes for bio traversal (as explained
in the last mail). Adds bi_voffset, bi_endvoffset fields
to the bio, request struct fields for tracking submission state,
and a process_that_request_first() routine for traversing a
request for i/o submission (without completion).


diff -ur linux-2.5.30-pure/drivers/block/elevator.c linux-2.5.30-bio/drivers/block/elevator.c
--- linux-2.5.30-pure/drivers/block/elevator.c Fri Aug 2 10:08:27 2002
+++ linux-2.5.30-bio/drivers/block/elevator.c Fri Aug 2 10:40:41 2002
@@ -236,6 +236,9 @@
if (!insert_here)
insert_here = q->queue_head.prev;

+ if (rq->bio)
+ BIO_BUG_ON(!bio_consistent(rq->bio)); /* debug only */
+
if (!(rq->flags & REQ_BARRIER))
lat = latency[rq_data_dir(rq)];

@@ -309,6 +312,9 @@
void elevator_noop_add_request(request_queue_t *q, struct request *rq,
struct list_head *insert_here)
{
+ if (rq->bio)
+ BIO_BUG_ON(!bio_consistent(rq->bio)); /* debug only */
+
list_add_tail(&rq->queuelist, &q->queue_head);

/*
@@ -389,6 +395,9 @@
void __elv_add_request(request_queue_t *q, struct request *rq,
struct list_head *insert_here)
{
+ if (rq->bio)
+ BIO_BUG_ON(!bio_consistent(rq->bio)); /* debug only */
+
q->elevator.elevator_add_req_fn(q, rq, insert_here);
}

@@ -412,7 +421,19 @@

/*
* all ok, break and return it
+ * after presetting some fields (e.g. the req might
+ * have been restarted)
*/
+ if ((rq->bio = rq->hard_bio)) {
+ rq->nr_bio_segments = bio_segments(rq->bio);
+ rq->nr_bio_sectors = bio_sectors(rq->bio);
+ rq->hard_cur_sectors = bio_segsize(rq->bio) >> 9;
+ rq->buffer = bio_data(rq->bio);
+ }
+ rq->sector = rq->hard_sector;
+ rq->nr_sectors = rq->hard_nr_sectors;
+ rq->current_nr_sectors = rq->hard_cur_sectors;
+
if (!q->prep_rq_fn(q, rq))
break;

@@ -425,6 +446,9 @@

end_that_request_last(rq);
}
+
+ if (rq->bio)
+ BIO_BUG_ON(!bio_consistent(rq->bio)); /* debug only */

return rq;
}
diff -ur linux-2.5.30-pure/drivers/block/ll_rw_blk.c linux-2.5.30-bio/drivers/block/ll_rw_blk.c
--- linux-2.5.30-pure/drivers/block/ll_rw_blk.c Fri Aug 2 10:08:27 2002
+++ linux-2.5.30-bio/drivers/block/ll_rw_blk.c Fri Aug 2 11:57:20 2002
@@ -569,10 +569,21 @@
{
struct bio_vec *bv, *bvprv = NULL;
int i, nr_phys_segs, nr_hw_segs, seg_size, cluster;
+ int offset;

if (unlikely(!bio->bi_io_vec))
return;

+ if (unlikely(bio->bi_idx >= bio->bi_vcnt))
+ return;
+
+ /*
+ * Relative offset into the first bvec where the data for
+ * this bio starts (may be non-zero for cloned bio split off
+ * in the middle of a segment)
+ */
+ offset = bio_startoffset(bio);
+
cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER);
seg_size = nr_phys_segs = nr_hw_segs = 0;
bio_for_each_segment(bv, bio, i) {
@@ -580,8 +591,12 @@
int phys, seg;

if (seg_size + bv->bv_len > q->max_segment_size) {
- nr_phys_segs++;
- goto new_segment;
+ if ((i != bio->bi_vcnt - 1) ||
+ (seg_size + bio->bi_endvoffset - bv->bv_offset
+ > q->max_segment_size)) {
+ nr_phys_segs++;
+ goto new_segment;
+ }
}

phys = BIOVEC_PHYS_MERGEABLE(bvprv, bv);
@@ -599,11 +614,17 @@
continue;
} else {
nr_phys_segs++;
+ nr_hw_segs++;
+ seg_size = bv->bv_len - offset;
+ bvprv = bv;
+ offset = 0; /* for all except the first bv */
+ continue;
}
new_segment:
nr_hw_segs++;
bvprv = bv;
seg_size = bv->bv_len;
+ offset = 0; /* for all except the first bv */
}

bio->bi_phys_segments = nr_phys_segs;
@@ -618,7 +639,8 @@
if (!(q->queue_flags & (1 << QUEUE_FLAG_CLUSTER)))
return 0;

- if (!BIOVEC_PHYS_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt)))
+ if (!BIOVEC_PHYS_MERGEABLE_PARTIAL(__BVEC_END(bio), bio->bi_endvoffset,
+ __BVEC_START(nxt), nxt->bi_voffset))
return 0;
if (bio->bi_size + nxt->bi_size > q->max_segment_size)
return 0;
@@ -639,7 +661,8 @@
if (!(q->queue_flags & (1 << QUEUE_FLAG_CLUSTER)))
return 0;

- if (!BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt)))
+ if (!BIOVEC_VIRT_MERGEABLE_PARTIAL(__BVEC_END(bio), bio->bi_endvoffset,
+ __BVEC_START(nxt), nxt->bi_voffset))
return 0;
if (bio->bi_size + nxt->bi_size > q->max_segment_size)
return 0;
@@ -663,6 +686,7 @@
struct bio_vec *bvec, *bvprv;
struct bio *bio;
int nsegs, i, cluster;
+ int offset, endoffset;

nsegs = 0;
cluster = q->queue_flags & (1 << QUEUE_FLAG_CLUSTER);
@@ -671,20 +695,27 @@
* for each bio in rq
*/
bvprv = NULL;
+ endoffset = 0;
rq_for_each_bio(bio, rq) {
/*
* for each segment in bio
*/
+ offset = bio_startoffset(bio);
bio_for_each_segment(bvec, bio, i) {
- int nbytes = bvec->bv_len;
+ int nbytes = bvec->bv_len - offset;
+ int start = bvec->bv_offset + offset;

if (bvprv && cluster) {
+ int end = bvprv->bv_offset + bvprv->bv_len -
+ endoffset;
if (sg[nsegs - 1].length + nbytes > q->max_segment_size)
goto new_segment;

- if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec))
+ if (!BIOVEC_PHYS_MERGEABLE_PARTIAL(bvprv,
+ end, bvec, start))
goto new_segment;
- if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec))
+ if (!BIOVEC_SEG_BOUNDARY_PARTIAL(q, bvprv,
+ end, bvec, start))
goto new_segment;

sg[nsegs - 1].length += nbytes;
@@ -693,12 +724,16 @@
memset(&sg[nsegs],0,sizeof(struct scatterlist));
sg[nsegs].page = bvec->bv_page;
sg[nsegs].length = nbytes;
- sg[nsegs].offset = bvec->bv_offset;
+ sg[nsegs].offset = bvec->bv_offset + offset;

nsegs++;
}
bvprv = bvec;
+ offset = 0;
+ endoffset = 0;
} /* segments in bio */
+ sg[nsegs - 1].length -= bio_endoffset(bio);
+ endoffset = bio_endoffset(bio);
} /* bios in rq */

return nsegs;
@@ -761,7 +796,9 @@
return 0;
}

- if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(req->biotail), __BVEC_START(bio)))
+ if (BIOVEC_VIRT_MERGEABLE_PARTIAL(__BVEC_END(req->biotail),
+ req->biotail->bi_endvoffset,
+ __BVEC_START(bio), bio->bi_voffset))
return ll_new_mergeable(q, req, bio);

return ll_new_hw_segment(q, req, bio);
@@ -776,7 +813,8 @@
return 0;
}

- if (BIOVEC_VIRT_MERGEABLE(__BVEC_END(bio), __BVEC_START(req->bio)))
+ if (BIOVEC_VIRT_MERGEABLE_PARTIAL(__BVEC_END(bio), bio->bi_endvoffset,
+ __BVEC_START(req->bio), req->bio->bi_voffset))
return ll_new_mergeable(q, req, bio);

return ll_new_hw_segment(q, req, bio);
@@ -1470,7 +1508,8 @@

sector = bio->bi_sector;
nr_sectors = bio_sectors(bio);
- cur_nr_sectors = bio_iovec(bio)->bv_len >> 9;
+ cur_nr_sectors = bio_segsize(bio) >> 9;
+
rw = bio_data_dir(bio);

/*
@@ -1520,8 +1559,12 @@
break;
}

+
bio->bi_next = req->bio;
- req->bio = bio;
+ req->hard_bio = req->bio = bio;
+ req->nr_bio_segments = bio_segments(req->bio);
+ req->nr_bio_sectors = bio_sectors(req->bio);
+
/*
* may not be valid. if the low level driver said
* it didn't need a bounce buffer then it better
@@ -1600,7 +1643,9 @@
req->nr_hw_segments = bio_hw_segments(q, bio);
req->buffer = bio_data(bio); /* see ->buffer comment above */
req->waiting = NULL;
- req->bio = req->biotail = bio;
+ req->hard_bio = req->bio = req->biotail = bio;
+ req->nr_bio_segments = bio_segments(req->bio);
+ req->nr_bio_sectors = bio_sectors(req->bio);
req->rq_dev = to_kdev_t(bio->bi_bdev->bd_dev);
add_request(q, req, insert_here);
out:
@@ -1749,6 +1794,10 @@

BIO_BUG_ON(!bio->bi_size);
BIO_BUG_ON(!bio->bi_io_vec);
+ BIO_BUG_ON(bio->bi_idx >= bio->bi_vcnt);
+
+ /* This is in now for debugging purposes */
+ BIO_BUG_ON(!bio_consistent(bio));

bio->bi_rw = rw;

@@ -1799,6 +1848,8 @@
bio->bi_vcnt = 1;
bio->bi_idx = 0;
bio->bi_size = bh->b_size;
+ bio->bi_voffset = bio->bi_io_vec[0].bv_offset;
+ bio->bi_endvoffset = bio->bi_voffset + bio->bi_size;

bio->bi_end_io = end_bio_bh_io_sync;
bio->bi_private = bh;
@@ -1921,10 +1972,8 @@
struct bio *bio;
int nr_phys_segs, nr_hw_segs;

- rq->buffer = bio_data(rq->bio);
-
nr_phys_segs = nr_hw_segs = 0;
- rq_for_each_bio(bio, rq) {
+ rq_for_each_unfin_bio(bio, rq) {
/* Force bio hw/phys segs to be recalculated. */
bio->bi_flags &= ~(1 << BIO_SEG_VALID);

@@ -1936,15 +1985,27 @@
rq->nr_hw_segments = nr_hw_segs;
}

-inline void blk_recalc_rq_sectors(struct request *rq, int nsect)
+void blk_recalc_rq_sectors(struct request *rq, int nsect)
{
if (rq->flags & REQ_CMD) {
+
rq->hard_sector += nsect;
- rq->nr_sectors = rq->hard_nr_sectors -= nsect;
- rq->sector = rq->hard_sector;
+ rq->hard_nr_sectors -= nsect;

- rq->current_nr_sectors = bio_iovec(rq->bio)->bv_len >> 9;
- rq->hard_cur_sectors = rq->current_nr_sectors;
+ /* Move the i/o submission pointers ahead if required */
+ /* (i.e. if the driver doesn't update them) */
+ if ((rq->nr_sectors >= rq->hard_nr_sectors) &&
+ (rq->sector <= rq->hard_sector)){
+ rq->sector = rq->hard_sector;
+ rq->nr_sectors = rq->hard_nr_sectors;
+ rq->bio = rq->hard_bio;
+ rq->nr_bio_segments = bio_segments(rq->bio);
+ rq->nr_bio_sectors = bio_sectors(rq->bio);
+ rq->hard_cur_sectors = bio_segsize(rq->bio) >> 9;
+ rq->current_nr_sectors = rq->hard_cur_sectors;
+
+ rq->buffer = bio_data(rq->bio);
+ }

/*
* if total number of sectors is less than the first segment
@@ -1977,27 +2038,35 @@
int nsect, total_nsect;
struct bio *bio;

+
req->errors = 0;
if (!uptodate)
printk("end_request: I/O error, dev %s, sector %lu\n",
kdevname(req->rq_dev), req->sector);

total_nsect = 0;
- while ((bio = req->bio)) {
- nsect = bio_iovec(bio)->bv_len >> 9;

- BIO_BUG_ON(bio_iovec(bio)->bv_len > bio->bi_size);
+ /* our starting point may be in the middle of a segment */
+ while ((bio = req->hard_bio)) {
+
+ /* For debugging - Verify consistency */
+ BIO_BUG_ON(!bio_consistent(bio));
+
+ nsect = bio_segsize(bio) >> 9;

/*
* not a complete bvec done
*/
if (unlikely(nsect > nr_sectors)) {
- int residual = (nsect - nr_sectors) << 9;

- bio->bi_size -= residual;
- bio_iovec(bio)->bv_offset += residual;
- bio_iovec(bio)->bv_len -= residual;
+ bio->bi_size -= nr_sectors << 9;
+ bio->bi_voffset += nr_sectors << 9;
blk_recalc_rq_sectors(req, nr_sectors);
+
+ /*
+ * TBD: Could we just do without recalc segments ?
+ * (or a better way to achieve it)
+ */
blk_recalc_rq_segments(req);
return 1;
}
@@ -2005,28 +2074,34 @@
/*
* account transfer
*/
- bio->bi_size -= bio_iovec(bio)->bv_len;
+ bio->bi_size -= nsect << 9;
bio->bi_idx++;

nr_sectors -= nsect;
total_nsect += nsect;

if (!bio->bi_size) {
- req->bio = bio->bi_next;
-
+ req->hard_bio = bio->bi_next;
bio_endio(bio, uptodate);
-
total_nsect = 0;
+ } else {
+ bio->bi_voffset = bio_iovec(bio)->bv_offset;
}

- if ((bio = req->bio)) {
+ if ((bio = req->hard_bio)) {
+ BIO_BUG_ON(bio_segments(bio) <= 0);
blk_recalc_rq_sectors(req, nsect);

/*
* end more in this run, or just return 'not-done'
*/
if (unlikely(nr_sectors <= 0)) {
- blk_recalc_rq_segments(req);
+ /*
+ *TBD:Could we just do without recalc segments ?
+ * (or a better way to achieve it)
+ */
+ blk_recalc_rq_segments(req);
+
return 1;
}
}
@@ -2043,6 +2118,81 @@
blk_put_request(req);
}

+/*
+ * blk_rq_next_segment
+ * @req: the request being processed
+ *
+ * Points to the next segment in the request if the current segment
+ * is complete. Leaves things unchanged if this segment is not over or
+ * if no more segments are left in this request.
+ *
+ * Meant to be used for bio traversal during i/o submission
+ * Does not effect any i/o completions or update completion state in
+ * the request, and does not modify any bio fields
+ *
+ * Decrementing rq->nr_sectors, rq->current_nr_sectors, and
+ * rq->nr_bio_sectors as data is transferred is the caller's
+ * responsibility and should be done before calling this routine.
+ */
+void blk_rq_next_segment(struct request *rq)
+{
+ if (rq->current_nr_sectors > 0)
+ return;
+
+ if (rq->nr_bio_sectors > 0) {
+ --rq->nr_bio_segments;
+ /* a clone bio could end in the middle of a segment */
+ rq->current_nr_sectors = min(
+ (unsigned long)blk_rq_vec(rq)->bv_len >> 9,
+ rq->nr_bio_sectors);
+ } else {
+ if ((rq->bio = rq->bio->bi_next)) {
+ rq->nr_bio_segments = bio_segments(rq->bio);
+ rq->nr_bio_sectors = bio_sectors(rq->bio);
+ rq->current_nr_sectors = bio_segsize(rq->bio) >> 9;
+ }
+ }
+
+ /* remember the size of this segment before we start i/o */
+ rq->hard_cur_sectors = rq->current_nr_sectors;
+}
+
+/*
+ * process_that_request_first: process partial request submission
+ * @req: the request being processed
+ * @nr_sectors: number of sectors i/o has been submitted on
+ *
+ * Description:
+ * May be used for processing bio's while submitting i/o without
+ * signalling completion. Fails if more data is requested than is
+ * available in the request in which case it doesn't advance any
+ * pointers.
+ *
+ * Assumes a request is correctly set up. No sanity checks)
+ *
+ * Return:
+ * 0 - no more data left to submit (not processed)
+ * 1 - data available to submit for this request (processed)
+ */
+int process_that_request_first(struct request *req, unsigned int nr_sectors)
+{
+ int nsect;
+
+ if (req->nr_sectors < nr_sectors)
+ return 0;
+
+ req->nr_sectors -= nr_sectors;
+ req->sector += nr_sectors;
+ while (nr_sectors) {
+ nsect = min(req->current_nr_sectors, nr_sectors);
+ req->current_nr_sectors -= nsect;
+ req->nr_bio_sectors -= nsect;
+ nr_sectors -= nsect;
+ blk_rq_next_segment(req);
+ }
+ return 1;
+}
+
#define MB(kb) ((kb) << 10)

int __init blk_dev_init(void)
@@ -2095,6 +2245,7 @@

EXPORT_SYMBOL(end_that_request_first);
EXPORT_SYMBOL(end_that_request_last);
+EXPORT_SYMBOL(process_that_request_first);
EXPORT_SYMBOL(blk_init_queue);
EXPORT_SYMBOL(bdev_get_queue);
EXPORT_SYMBOL(blk_cleanup_queue);
diff -ur linux-2.5.30-pure/fs/bio.c linux-2.5.30-bio/fs/bio.c
--- linux-2.5.30-pure/fs/bio.c Sat Jul 27 08:28:39 2002
+++ linux-2.5.30-bio/fs/bio.c Fri Aug 2 10:34:38 2002
@@ -178,6 +178,28 @@
}
}

+/* Perform some sanity checks on the bio vectors, size and offsets */
+int bio_consistent(struct bio *bio)
+{
+ struct bio_vec *bvec;
+ int i;
+ int size = 0;
+
+ /* Verify that the size is consistent with sigma vec len */
+ bio_for_each_segment(bvec, bio, i)
+ size += bvec->bv_len;
+
+ /* Adjust for both ends */
+ size -= bio_startoffset(bio) + bio_endoffset(bio);
+
+ if (size != bio->bi_size)
+ return 0; /* size mismatch */
+
+ /* Place any other checks here */
+
+ return 1;
+}
+
inline int bio_phys_segments(request_queue_t *q, struct bio *bio)
{
if (unlikely(!(bio->bi_flags & (1 << BIO_SEG_VALID))))
@@ -225,6 +247,8 @@
}
bio->bi_size = bio_src->bi_size;
bio->bi_max = bio_src->bi_max;
+ bio->bi_voffset = bio_src->bi_voffset;
+ bio->bi_endvoffset = bio_src->bi_endvoffset;
}

/**
@@ -312,6 +336,9 @@
b->bi_vcnt = bio->bi_vcnt;
b->bi_size = bio->bi_size;

+ b->bi_voffset = bio->bi_voffset;
+ b->bi_endvoffset = bio->bi_endvoffset;
+
return b;

oom:
@@ -424,6 +451,9 @@
}

queue_io:
+ bio->bi_voffset = bio_iovec(bio)->bv_offset;
+ bio->bi_endvoffset = __BVEC_END(bio)->bv_offset +
+ __BVEC_END(bio)->bv_len;
submit_bio(rw, bio);

if (total_nr_pages)
diff -ur linux-2.5.30-pure/include/linux/bio.h linux-2.5.30-bio/include/linux/bio.h
--- linux-2.5.30-pure/include/linux/bio.h Sat Jul 27 08:28:41 2002
+++ linux-2.5.30-bio/include/linux/bio.h Fri Aug 2 11:56:12 2002
@@ -67,7 +67,22 @@
*/

unsigned short bi_vcnt; /* how many bio_vec's */
+
+ /*
+ * Residual section - portion on which i/o hasn't finished as yet
+ * (i/o may already have been submitted and in progress for some
+ * of these segments if this is an active bio)
+ */
unsigned short bi_idx; /* current index into bvl_vec */
+ unsigned short bi_voffset; /* current vec offset -
+ * relative to start of bvec
+ * page
+ */
+ unsigned short bi_endvoffset; /* offset into the last bvec
+ * page that marks the end of
+ * this buffer
+ */
+ unsigned int bi_size; /* residual I/O count */

/* Number of segments in this BIO after
* physical address coalescing is performed.
@@ -79,7 +94,6 @@
*/
unsigned short bi_hw_segments;

- unsigned int bi_size; /* residual I/O count */
unsigned int bi_max; /* max bvl_vecs we can hold,
used as index into pool */

@@ -120,11 +134,13 @@
#define bio_iovec_idx(bio, idx) (&((bio)->bi_io_vec[(idx)]))
#define bio_iovec(bio) bio_iovec_idx((bio), (bio)->bi_idx)
#define bio_page(bio) bio_iovec((bio))->bv_page
-#define bio_offset(bio) bio_iovec((bio))->bv_offset
+#define bio_offset(bio) (bio)->bi_voffset
+#define bio_segments(bio) ((bio)->bi_vcnt - (bio)->bi_idx)
#define bio_sectors(bio) ((bio)->bi_size >> 9)
#define bio_data(bio) (page_address(bio_page((bio))) + bio_offset((bio)))
#define bio_barrier(bio) ((bio)->bi_rw & (1 << BIO_BARRIER))

+
/*
* will die
*/
@@ -150,16 +166,38 @@
#define __BVEC_START(bio) bio_iovec_idx((bio), 0)
#define BIOVEC_PHYS_MERGEABLE(vec1, vec2) \
((bvec_to_phys((vec1)) + (vec1)->bv_len) == bvec_to_phys((vec2)))
+#define BIOVEC_PHYS_MERGEABLE_PARTIAL(vec1, end, vec2, start) \
+ ((page_to_phys((vec1)->bv_page) + (end)) == \
+ (page_to_phys((vec2)->bv_page) + (start)))
#define BIOVEC_VIRT_MERGEABLE(vec1, vec2) \
((((bvec_to_phys((vec1)) + (vec1)->bv_len) | bvec_to_phys((vec2))) & (BIO_VMERGE_BOUNDARY - 1)) == 0)
+#define BIOVEC_VIRT_MERGEABLE_PARTIAL(vec1, end, vec2, start) \
+ ((((page_to_phys((vec1)->bv_page) + (end)) | (page_to_phys((vec2)->bv_page) + (start))) & (BIO_VMERGE_BOUNDARY - 1)) == 0)
#define __BIO_SEG_BOUNDARY(addr1, addr2, mask) \
(((addr1) | (mask)) == (((addr2) - 1) | (mask)))
#define BIOVEC_SEG_BOUNDARY(q, b1, b2) \
__BIO_SEG_BOUNDARY(bvec_to_phys((b1)), bvec_to_phys((b2)) + (b2)->bv_len, (q)->seg_boundary_mask)
+#define BIOVEC_SEG_BOUNDARY_PARTIAL(q, b1, start, b2, end) \
+ __BIO_SEG_BOUNDARY(page_to_phys((b1)->bv_page) + (start), page_to_phys((b2)->bv_page) + (end), (q)->seg_boundary_mask)
#define BIO_SEG_BOUNDARY(q, b1, b2) \
- BIOVEC_SEG_BOUNDARY((q), __BVEC_END((b1)), __BVEC_START((b2)))
+ BIOVEC_SEG_BOUNDARY_PARTIAL((q), __BVEC_END((b1)),(b1)->bi_voffset, \
+ __BVEC_START((b2)), (b2)->bi_endvoffset)

#define bio_io_error(bio) bio_endio((bio), 0)
+#define bio_startoffset(bio) (bio_offset(bio) - bio_iovec(bio)->bv_offset)
+#define bio_endoffset(bio) (__BVEC_END(bio)->bv_offset + \
+ __BVEC_END(bio)->bv_len - (bio)->bi_endvoffset)
+
+/* adjusts for clones which may start or end in the middle of a segment */
+static inline unsigned int bio_segsize(struct bio *bio)
+{
+ unsigned int len = bio_iovec(bio)->bv_len - bio_startoffset(bio);
+
+ if (len > bio->bi_size)
+ len = bio->bi_size;
+
+ return len;
+}

/*
* drivers should not use the __ version unless they _really_ want to
@@ -203,6 +241,8 @@

extern inline void bio_init(struct bio *);

+extern int bio_consistent(struct bio *bio);
+
#ifdef CONFIG_HIGHMEM
/*
* remember to add offset! and never ever reenable interrupts between a
@@ -211,7 +251,7 @@
* This function MUST be inlined - it plays with the CPU interrupt flags.
* Hence the `extern inline'.
*/
-extern inline char *bio_kmap_irq(struct bio *bio, unsigned long *flags)
+extern inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)
{
unsigned long addr;

@@ -220,22 +260,23 @@
/*
* could be low
*/
- if (!PageHighMem(bio_page(bio)))
- return bio_data(bio);
+ if (!PageHighMem(bvec->bv_page))
+ return page_address(bvec->bv_page) + bvec->bv_offset;

/*
* it's a highmem page
*/
local_irq_disable();
- addr = (unsigned long) kmap_atomic(bio_page(bio), KM_BIO_SRC_IRQ);
+ addr = (unsigned long) kmap_atomic(bvec->bv_page, KM_BIO_SRC_IRQ);

if (addr & ~PAGE_MASK)
BUG();

- return (char *) addr + bio_offset(bio);
+ return (char *) addr + bvec->bv_offset;
}

-extern inline void bio_kunmap_irq(char *buffer, unsigned long *flags)
+
+extern inline void bvec_kunmap_irq(char *buffer, unsigned long *flags)
{
unsigned long ptr = (unsigned long) buffer & PAGE_MASK;

@@ -244,8 +285,19 @@
}

#else
-#define bio_kmap_irq(bio, flags) (bio_data(bio))
-#define bio_kunmap_irq(buf, flags) do { *(flags) = 0; } while (0)
+#define bvec_kmap_irq(bvec, flags) (page_address((bvec)->bv_page) + ((bvec)->bv_offset))
+#define bvec_kunmap_irq(buf, flags) do { *(flags) = 0; } while (0)
#endif
+
+
+/* TBD: Could this be made more efficient ? */
+extern inline char *__bio_kmap_irq(struct bio *bio, unsigned short idx,
+ unsigned long *flags)
+{
+ return bvec_kmap_irq(bio_iovec_idx(bio, idx), flags) +
+ ((idx == bio->bi_idx) ? bio_startoffset(bio): 0);
+}
+
+#define __bio_kunmap_irq bvec_kunmap_irq

#endif /* __LINUX_BIO_H */
diff -ur linux-2.5.30-pure/include/linux/blk.h linux-2.5.30-bio/include/linux/blk.h
--- linux-2.5.30-pure/include/linux/blk.h Sat Jul 27 08:28:41 2002
+++ linux-2.5.30-bio/include/linux/blk.h Fri Aug 2 10:34:38 2002
@@ -40,6 +40,7 @@

extern int end_that_request_first(struct request *, int, int);
extern void end_that_request_last(struct request *);
+extern int process_that_request_first(struct request *, unsigned int);
struct request *elv_next_request(request_queue_t *q);

static inline void blkdev_dequeue_request(struct request *req)
@@ -50,11 +51,14 @@
elv_remove_request(req->q, req);
}

+
+
#define _elv_add_request_core(q, rq, where, plug) \
do { \
if ((plug)) \
blk_plug_device((q)); \
(q)->elevator.elevator_add_req_fn((q), (rq), (where)); \
+ if ((rq)->bio) BIO_BUG_ON(!bio_consistent((rq)->bio)); \
} while (0)

#define _elv_add_request(q, rq, back, p) do { \
diff -ur linux-2.5.30-pure/include/linux/blkdev.h linux-2.5.30-bio/include/linux/blkdev.h
--- linux-2.5.30-pure/include/linux/blkdev.h Sat Jul 27 08:28:32 2002
+++ linux-2.5.30-bio/include/linux/blkdev.h Fri Aug 2 10:34:38 2002
@@ -10,6 +10,7 @@
#include <linux/backing-dev.h>

#include <asm/scatterlist.h>
+#include <linux/bio.h>

struct request_queue;
typedef struct request_queue request_queue_t;
@@ -35,13 +36,13 @@
int rq_status; /* should split this into a few status bits */
kdev_t rq_dev;
int errors;
- sector_t sector;
- unsigned long nr_sectors;
- unsigned long hard_sector; /* the hard_* are block layer
- * internals, no driver should
- * touch them
- */
- unsigned long hard_nr_sectors;
+ sector_t sector; /* next sector to submit */
+ unsigned long nr_sectors; /* no of sectors left to submit */
+
+ /* the hard_* are block layer internals, no driver should
+ touch them */
+ unsigned long hard_sector; /* next sector to complete */
+ unsigned long hard_nr_sectors; /* no. of sectors left to complete */

/* Number of scatter-gather DMA addr+len pairs after
* physical address coalescing is performed.
@@ -55,13 +56,26 @@
*/
unsigned short nr_hw_segments;

+ /* Maintain bio traversal state for part by part io submission */
+ /* "current" refers to an element currently being submitted for io */
+
+ /* no. of segments left to submit in the current bio */
+ unsigned short nr_bio_segments;
+ /* no. of sectors left to submit in the current bio */
+ unsigned long nr_bio_sectors;
+ /* no. of sectors left to submit in the current segment */
unsigned int current_nr_sectors;
+ /* no. of sectors left to complete in the current segment */
unsigned int hard_cur_sectors;
+
+ struct bio *bio; /* next bio to submit */
+ struct bio *hard_bio; /* next unfinished bio to complete */
+ struct bio *biotail;
+
int tag;
void *special;
char *buffer;
struct completion *waiting;
- struct bio *bio, *biotail;
request_queue_t *q;
struct request_list *rl;
};
@@ -232,6 +246,33 @@
*/
#define blk_queue_headactive(q, head_active)

+
+/*
+ * temporarily mapping a (possible) highmem bio for typically for PIO transfer
+ */
+
+/* current offset with respect to start of the segment being submitted */
+#define blk_rq_offset(rq) (((rq)->hard_cur_sectors - (rq)->current_nr_sectors) << 9)
+
+/* current index into bio being processed for submission */
+#define blk_rq_idx(rq) ((rq)->bio->bi_vcnt - (rq)->nr_bio_segments)
+
+/* current vector being processed */
+#define blk_rq_vec(rq) (bio_iovec_idx((rq)->bio, blk_rq_idx(rq)))
+
+/* Assumes rq->bio != NULL */
+static inline char *rq_map_buffer(struct request *rq, unsigned long *flags)
+{
+ return (__bio_kmap_irq(rq->bio, blk_rq_idx(rq), flags)
+ + blk_rq_offset(rq));
+}
+
+static inline void rq_unmap_buffer(char *buffer, unsigned long *flags)
+{
+ __bio_kunmap_irq(buffer, flags);
+}
+
+
extern unsigned long blk_max_low_pfn, blk_max_pfn;

/*
@@ -251,6 +292,10 @@
#define rq_for_each_bio(bio, rq) \
if ((rq->bio)) \
for (bio = (rq)->bio; bio; bio = bio->bi_next)
+
+#define rq_for_each_unfin_bio(bio, rq) \
+ if ((rq->hard_bio)) \
+ for (bio = (rq)->hard_bio; bio; bio = bio->bi_next)

struct blk_dev_struct {
/*
diff -ur linux-2.5.30-pure/mm/highmem.c linux-2.5.30-bio/mm/highmem.c
--- linux-2.5.30-pure/mm/highmem.c Sat Jul 27 08:28:27 2002
+++ linux-2.5.30-bio/mm/highmem.c Fri Aug 2 10:34:38 2002
@@ -432,8 +432,10 @@
bio->bi_rw = (*bio_orig)->bi_rw;

bio->bi_vcnt = (*bio_orig)->bi_vcnt;
- bio->bi_idx = 0;
+ bio->bi_idx = (*bio_orig)->bi_idx;
bio->bi_size = (*bio_orig)->bi_size;
+ bio->bi_voffset = (*bio_orig)->bi_voffset;
+ bio->bi_endvoffset = (*bio_orig)->bi_endvoffset;

if (pool == page_pool) {
if (rw & WRITE)
@@ -446,6 +448,8 @@
else
bio->bi_end_io = bounce_end_io_read_isa;
}
+
+ BIO_BUG_ON(!bio_consistent(bio)); /* debug only */

bio->bi_private = *bio_orig;
*bio_orig = bio;
-
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