From: Milan Broz Date: Tue, 3 Oct 2006 08:15:39 +0000 (-0700) Subject: [PATCH] dm crypt: move io to workqueue X-Git-Tag: v2.6.19-rc1~258 X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=23541d2d288cdb54f417ba1001dacc7f3ea10a97;p=linux-2.6-omap-h63xx.git [PATCH] dm crypt: move io to workqueue This patch is designed to help dm-crypt comply with the new constraints imposed by the following patch in -mm: md-dm-reduce-stack-usage-with-stacked-block-devices.patch Under low memory the existing implementation relies upon waiting for I/O submitted recursively to generic_make_request() completing before the original generic_make_request() call can return. This patch moves the I/O submission to a workqueue so the original generic_make_request() can return immediately. Signed-off-by: Milan Broz Signed-off-by: Alasdair G Kergon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c index 946a9ebc89d..c34433a6edd 100644 --- a/drivers/md/dm-crypt.c +++ b/drivers/md/dm-crypt.c @@ -35,6 +35,7 @@ struct crypt_io { struct work_struct work; atomic_t pending; int error; + int post_process; }; /* @@ -445,8 +446,7 @@ static void dec_pending(struct crypt_io *io, int error) * kcryptd: * * Needed because it would be very unwise to do decryption in an - * interrupt context, so bios returning from read requests get - * queued here. + * interrupt context. */ static struct workqueue_struct *_kcryptd_workqueue; static void kcryptd_do_work(void *data); @@ -470,12 +470,10 @@ static int crypt_endio(struct bio *clone, unsigned int done, int error) if (!read_io) crypt_free_buffer_pages(cc, clone, done); + /* keep going - not finished yet */ if (unlikely(clone->bi_size)) return 1; - /* - * successful reads are decrypted by the worker thread - */ if (!read_io) goto out; @@ -485,6 +483,7 @@ static int crypt_endio(struct bio *clone, unsigned int done, int error) } bio_put(clone); + io->post_process = 1; kcryptd_queue_io(io); return 0; @@ -504,7 +503,7 @@ static void clone_init(struct crypt_io *io, struct bio *clone) clone->bi_rw = io->base_bio->bi_rw; } -static int process_read(struct crypt_io *io) +static void process_read(struct crypt_io *io) { struct crypt_config *cc = io->target->private; struct bio *base_bio = io->base_bio; @@ -521,7 +520,7 @@ static int process_read(struct crypt_io *io) clone = bio_alloc(GFP_NOIO, bio_segments(base_bio)); if (unlikely(!clone)) { dec_pending(io, -ENOMEM); - return 0; + return; } clone_init(io, clone); @@ -533,11 +532,9 @@ static int process_read(struct crypt_io *io) sizeof(struct bio_vec) * clone->bi_vcnt); generic_make_request(clone); - - return 0; } -static int process_write(struct crypt_io *io) +static void process_write(struct crypt_io *io) { struct crypt_config *cc = io->target->private; struct bio *base_bio = io->base_bio; @@ -558,15 +555,18 @@ static int process_write(struct crypt_io *io) while (remaining) { clone = crypt_alloc_buffer(cc, base_bio->bi_size, io->first_clone, &bvec_idx); - if (unlikely(!clone)) - goto cleanup; + if (unlikely(!clone)) { + dec_pending(io, -ENOMEM); + return; + } ctx.bio_out = clone; if (unlikely(crypt_convert(cc, &ctx) < 0)) { crypt_free_buffer_pages(cc, clone, clone->bi_size); bio_put(clone); - goto cleanup; + dec_pending(io, -EIO); + return; } clone_init(io, clone); @@ -582,31 +582,20 @@ static int process_write(struct crypt_io *io) io->first_clone = clone; } - atomic_inc(&io->pending); - remaining -= clone->bi_size; sector += bio_sectors(clone); + /* prevent bio_put of first_clone */ + if (remaining) + atomic_inc(&io->pending); + generic_make_request(clone); /* out of memory -> run queues */ if (remaining) blk_congestion_wait(bio_data_dir(clone), HZ/100); - } - /* drop reference, clones could have returned before we reach this */ - dec_pending(io, 0); - return 0; - -cleanup: - if (io->first_clone) { - dec_pending(io, -ENOMEM); - return 0; } - - /* if no bio has been dispatched yet, we can directly return the error */ - mempool_free(io, cc->io_pool); - return -ENOMEM; } static void process_read_endio(struct crypt_io *io) @@ -624,7 +613,12 @@ static void kcryptd_do_work(void *data) { struct crypt_io *io = data; - process_read_endio(io); + if (io->post_process) + process_read_endio(io); + else if (bio_data_dir(io->base_bio) == READ) + process_read(io); + else + process_write(io); } /* @@ -889,17 +883,14 @@ static int crypt_map(struct dm_target *ti, struct bio *bio, struct crypt_io *io; io = mempool_alloc(cc->io_pool, GFP_NOIO); - io->target = ti; io->base_bio = bio; io->first_clone = NULL; - io->error = 0; + io->error = io->post_process = 0; atomic_set(&io->pending, 0); + kcryptd_queue_io(io); - if (bio_data_dir(bio) == WRITE) - return process_write(io); - - return process_read(io); + return 0; } static int crypt_status(struct dm_target *ti, status_type_t type, @@ -999,7 +990,7 @@ error: static struct target_type crypt_target = { .name = "crypt", - .version= {1, 2, 0}, + .version= {1, 3, 0}, .module = THIS_MODULE, .ctr = crypt_ctr, .dtr = crypt_dtr,