From mboxrd@z Thu Jan 1 00:00:00 1970 From: Olaf Kirch Subject: [PATCH 4/3] Allocate smaller clones Date: Wed, 21 Mar 2007 11:47:15 +0100 Message-ID: <200703211147.16032.okir@lst.de> References: <200703210806.30499.okir@lst.de> <20070321100312.GF27600@agk.surrey.redhat.com> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20070321100312.GF27600@agk.surrey.redhat.com> Content-Disposition: inline List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: dm-devel@redhat.com, Andrew Morton , Alasdair G Kergon List-Id: dm-devel.ids Hi Alasdair, FWIW, here's a fourth patch that tidies up crypt_allocate_buffer a little. It's not strictly required to fix the bug, but the code looks simpler this way, I think. Olaf ------------------------ 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@oracle.com --- drivers/md/dm-crypt.c | 28 ++++++++-------------------- 1 file changed, 8 insertions(+), 20 deletions(-) Index: linux-2.6.20/drivers/md/dm-crypt.c =================================================================== --- linux-2.6.20.orig/drivers/md/dm-crypt.c +++ linux-2.6.20/drivers/md/dm-crypt.c @@ -380,7 +380,7 @@ static int crypt_convert(struct crypt_co * 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) +crypt_alloc_buffer(struct crypt_io *io, unsigned int size) { struct crypt_config *cc = io->target->private; struct bio *clone; @@ -394,16 +394,7 @@ crypt_alloc_buffer(struct crypt_io *io, 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 +406,7 @@ crypt_alloc_buffer(struct crypt_io *io, * 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 +425,6 @@ crypt_alloc_buffer(struct crypt_io *io, 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 +582,6 @@ 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 +592,14 @@ 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 +608,9 @@ 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); -- Olaf Kirch | --- o --- Nous sommes du soleil we love when we play okir@lst.de | / | \ sol.dhoop.naytheet.ah kin.ir.samse.qurax