From: olaf.kirch@xxxxxxxxxx
Allocate smaller clones
With the previous dm-crypt fixes, there is no need for the clone
bios to have the same bvec size as the original - we just
need to make them big enough for the remaining number of
pages. The only requirement is that we clear the "out" index
in convert_context, so that crypt_convert starts storing data
at the right position within the clone bio.
Signed-off-by: olaf.kirch@xxxxxxxxxx
Signed-off-by: Alasdair G Kergon <agk@xxxxxxxxxx>
---
drivers/md/dm-crypt.c | 29 ++++++++---------------------
1 files changed, 8 insertions(+), 21 deletions(-)
Index: linux-2.6.21/drivers/md/dm-crypt.c
===================================================================
--- linux-2.6.21.orig/drivers/md/dm-crypt.c 2007-05-01 17:40:48.000000000 +0100
+++ linux-2.6.21/drivers/md/dm-crypt.c 2007-05-01 17:40:49.000000000 +0100
@@ -379,8 +379,7 @@ static int crypt_convert(struct crypt_co
* This should never violate the device limitations
* May return a smaller bio when running out of pages
*/
-static struct bio *crypt_alloc_buffer(struct crypt_io *io, unsigned int size,
- unsigned int *bio_vec_idx)
+static struct bio *crypt_alloc_buffer(struct crypt_io *io, unsigned int size)
{
struct crypt_config *cc = io->target->private;
struct bio *clone;
@@ -394,16 +393,7 @@ static struct bio *crypt_alloc_buffer(st
clone_init(io, clone);
- /* if the last bio was not complete, continue where that one ended */
- clone->bi_idx = *bio_vec_idx;
- clone->bi_vcnt = *bio_vec_idx;
- clone->bi_size = 0;
- clone->bi_flags &= ~(1 << BIO_SEG_VALID);
-
- /* clone->bi_idx pages have already been allocated */
- size -= clone->bi_idx * PAGE_SIZE;
-
- for (i = clone->bi_idx; i < nr_iovecs; i++) {
+ for (i = 0; i < nr_iovecs; i++) {
struct bio_vec *bv = bio_iovec_idx(clone, i);
bv->bv_page = mempool_alloc(cc->page_pool, gfp_mask);
@@ -415,7 +405,7 @@ static struct bio *crypt_alloc_buffer(st
* return a partially allocated bio, the caller will then try
* to allocate additional bios while submitting this partial bio
*/
- if ((i - clone->bi_idx) == (MIN_BIO_PAGES - 1))
+ if (i == (MIN_BIO_PAGES - 1))
gfp_mask = (gfp_mask | __GFP_NOWARN) & ~__GFP_WAIT;
bv->bv_offset = 0;
@@ -434,12 +424,6 @@ static struct bio *crypt_alloc_buffer(st
return NULL;
}
- /*
- * Remember the last bio_vec allocated to be able
- * to correctly continue after the splitting.
- */
- *bio_vec_idx = clone->bi_vcnt;
-
return clone;
}
@@ -597,7 +581,6 @@ static void process_write(struct crypt_i
struct convert_context ctx;
unsigned remaining = base_bio->bi_size;
sector_t sector = base_bio->bi_sector - io->target->begin;
- unsigned bvec_idx = 0;
atomic_inc(&io->pending);
@@ -608,13 +591,14 @@ static void process_write(struct crypt_i
* so repeat the whole process until all the data can be handled.
*/
while (remaining) {
- clone = crypt_alloc_buffer(io, base_bio->bi_size, &bvec_idx);
+ clone = crypt_alloc_buffer(io, remaining);
if (unlikely(!clone)) {
dec_pending(io, -ENOMEM);
return;
}
ctx.bio_out = clone;
+ ctx.idx_out = 0;
if (unlikely(crypt_convert(cc, &ctx) < 0)) {
crypt_free_buffer_pages(cc, clone, clone->bi_size);
@@ -623,6 +607,9 @@ static void process_write(struct crypt_i
return;
}
+ /* crypt_convert should have filled the clone bio */
+ BUG_ON(ctx.idx_out < clone->bi_vcnt);
+
clone->bi_sector = cc->start + sector;
remaining -= clone->bi_size;
sector += bio_sectors(clone);
--
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