dm-crypt: don't allocate pages for a partial request. This patch changes crypt_alloc_buffer so that it always allocates pages for a full request. This change enables further simplification and removing of one refcounts in the next patches. Note: the next patch is needed to fix a theoretical deadlock Signed-off-by: Mikulas Patocka --- drivers/md/dm-crypt.c | 139 ++++++++++---------------------------------------- 1 file changed, 30 insertions(+), 109 deletions(-) Index: linux-3.18-rc1/drivers/md/dm-crypt.c =================================================================== --- linux-3.18-rc1.orig/drivers/md/dm-crypt.c 2014-10-21 00:49:28.000000000 +0200 +++ linux-3.18-rc1/drivers/md/dm-crypt.c 2014-10-21 00:49:31.000000000 +0200 @@ -58,7 +58,6 @@ struct dm_crypt_io { atomic_t io_pending; int error; sector_t sector; - struct dm_crypt_io *base_io; } CRYPTO_MINALIGN_ATTR; struct dm_crypt_request { @@ -172,7 +171,6 @@ struct crypt_config { }; #define MIN_IOS 16 -#define MIN_POOL_PAGES 32 static struct kmem_cache *_crypt_io_pool; @@ -946,14 +944,13 @@ static int crypt_convert(struct crypt_co return 0; } +static void crypt_free_buffer_pages(struct crypt_config *cc, struct bio *clone); + /* * Generate a new unfragmented bio with the given size * This should never violate the device limitations - * May return a smaller bio when running out of pages, indicated by - * *out_of_pages set to 1. */ -static struct bio *crypt_alloc_buffer(struct dm_crypt_io *io, unsigned size, - unsigned *out_of_pages) +static struct bio *crypt_alloc_buffer(struct dm_crypt_io *io, unsigned size) { struct crypt_config *cc = io->cc; struct bio *clone; @@ -961,41 +958,27 @@ static struct bio *crypt_alloc_buffer(st gfp_t gfp_mask = GFP_NOIO | __GFP_HIGHMEM; unsigned i, len; struct page *page; + struct bio_vec *bvec; clone = bio_alloc_bioset(GFP_NOIO, nr_iovecs, cc->bs); if (!clone) return NULL; clone_init(io, clone); - *out_of_pages = 0; for (i = 0; i < nr_iovecs; i++) { page = mempool_alloc(cc->page_pool, gfp_mask); - if (!page) { - *out_of_pages = 1; - break; - } - - /* - * If additional pages cannot be allocated without waiting, - * return a partially-allocated bio. The caller will then try - * to allocate more bios while submitting this partial bio. - */ - gfp_mask = (gfp_mask | __GFP_NOWARN) & ~__GFP_WAIT; len = (size > PAGE_SIZE) ? PAGE_SIZE : size; - if (!bio_add_page(clone, page, len, 0)) { - mempool_free(page, cc->page_pool); - break; - } + bvec = &clone->bi_io_vec[clone->bi_vcnt++]; + bvec->bv_page = page; + bvec->bv_len = len; + bvec->bv_offset = 0; - size -= len; - } + clone->bi_iter.bi_size += len; - if (!clone->bi_iter.bi_size) { - bio_put(clone); - return NULL; + size -= len; } return clone; @@ -1020,7 +1003,6 @@ static void crypt_io_init(struct dm_cryp io->base_bio = bio; io->sector = sector; io->error = 0; - io->base_io = NULL; io->ctx.req = NULL; atomic_set(&io->io_pending, 0); } @@ -1033,13 +1015,11 @@ static void crypt_inc_pending(struct dm_ /* * One of the bios was finished. Check for completion of * the whole request and correctly clean up the buffer. - * If base_io is set, wait for the last fragment to complete. */ static void crypt_dec_pending(struct dm_crypt_io *io) { struct crypt_config *cc = io->cc; struct bio *base_bio = io->base_bio; - struct dm_crypt_io *base_io = io->base_io; int error = io->error; if (!atomic_dec_and_test(&io->io_pending)) @@ -1050,13 +1030,7 @@ static void crypt_dec_pending(struct dm_ if (io != dm_per_bio_data(base_bio, cc->per_bio_data_size)) mempool_free(io, cc->io_pool); - if (likely(!base_io)) - bio_endio(base_bio, error); - else { - if (error && !base_io->error) - base_io->error = error; - crypt_dec_pending(base_io); - } + bio_endio(base_bio, error); } /* @@ -1192,10 +1166,7 @@ static void kcryptd_crypt_write_convert( { struct crypt_config *cc = io->cc; struct bio *clone; - struct dm_crypt_io *new_io; int crypt_finished; - unsigned out_of_pages = 0; - unsigned remaining = io->base_bio->bi_iter.bi_size; sector_t sector = io->sector; int r; @@ -1205,80 +1176,30 @@ static void kcryptd_crypt_write_convert( crypt_inc_pending(io); crypt_convert_init(cc, &io->ctx, NULL, io->base_bio, sector); - /* - * The allocated buffers can be smaller than the whole bio, - * so repeat the whole process until all the data can be handled. - */ - while (remaining) { - clone = crypt_alloc_buffer(io, remaining, &out_of_pages); - if (unlikely(!clone)) { - io->error = -ENOMEM; - break; - } - - io->ctx.bio_out = clone; - io->ctx.iter_out = clone->bi_iter; - - remaining -= clone->bi_iter.bi_size; - sector += bio_sectors(clone); - - crypt_inc_pending(io); - - r = crypt_convert(cc, &io->ctx); - if (r < 0) - io->error = -EIO; - - crypt_finished = atomic_dec_and_test(&io->ctx.cc_pending); - - /* Encryption was already finished, submit io now */ - if (crypt_finished) { - kcryptd_crypt_write_io_submit(io, 0); - - /* - * If there was an error, do not try next fragments. - * For async, error is processed in async handler. - */ - if (unlikely(r < 0)) - break; + clone = crypt_alloc_buffer(io, io->base_bio->bi_iter.bi_size); + if (unlikely(!clone)) { + io->error = -EIO; + goto dec; + } - io->sector = sector; - } + io->ctx.bio_out = clone; + io->ctx.iter_out = clone->bi_iter; - /* - * Out of memory -> run queues - * But don't wait if split was due to the io size restriction - */ - if (unlikely(out_of_pages)) - congestion_wait(BLK_RW_ASYNC, HZ/100); + sector += bio_sectors(clone); - /* - * With async crypto it is unsafe to share the crypto context - * between fragments, so switch to a new dm_crypt_io structure. - */ - if (unlikely(!crypt_finished && remaining)) { - new_io = mempool_alloc(cc->io_pool, GFP_NOIO); - crypt_io_init(new_io, io->cc, io->base_bio, sector); - crypt_inc_pending(new_io); - crypt_convert_init(cc, &new_io->ctx, NULL, - io->base_bio, sector); - new_io->ctx.iter_in = io->ctx.iter_in; - - /* - * Fragments after the first use the base_io - * pending count. - */ - if (!io->base_io) - new_io->base_io = io; - else { - new_io->base_io = io->base_io; - crypt_inc_pending(io->base_io); - crypt_dec_pending(io); - } + crypt_inc_pending(io); + r = crypt_convert(cc, &io->ctx); + if (r) + io->error = -EIO; + crypt_finished = atomic_dec_and_test(&io->ctx.cc_pending); - io = new_io; - } + /* Encryption was already finished, submit io now */ + if (crypt_finished) { + kcryptd_crypt_write_io_submit(io, 0); + io->sector = sector; } +dec: crypt_dec_pending(io); } @@ -1746,7 +1667,7 @@ static int crypt_ctr(struct dm_target *t sizeof(struct dm_crypt_request) + iv_size_padding + cc->iv_size, ARCH_KMALLOC_MINALIGN); - cc->page_pool = mempool_create_page_pool(MIN_POOL_PAGES, 0); + cc->page_pool = mempool_create_page_pool(BIO_MAX_PAGES, 0); if (!cc->page_pool) { ti->error = "Cannot allocate page mempool"; goto bad;