From 94e795a12c0fdd2c86f4c22b6857a99a4c0cf1d7 Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Fri, 9 May 2014 17:03:15 -0400 Subject: [RHEL6.6 PATCH 03/11] dm crypt: use io thread for reads only if mempool exhausted BZ: 1076147 Upstream commit 20c82538e4f5ede51bc2b4795bc6e5cae772796d Author: Milan Broz Date: Thu Jan 13 19:59:53 2011 +0000 dm crypt: use io thread for reads only if mempool exhausted If there is enough memory, code can directly submit bio instead queing this operation in separate thread. Try to alloc bio clone with GFP_NOWAIT and only if it fails use separate queue (map function cannot block here). Signed-off-by: Milan Broz Signed-off-by: Alasdair G Kergon --- drivers/md/dm-crypt.c | 37 +++++++++++++++++++++++-------------- 1 files changed, 23 insertions(+), 14 deletions(-) diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c index 821538b..a404d51 100644 --- a/drivers/md/dm-crypt.c +++ b/drivers/md/dm-crypt.c @@ -784,26 +784,30 @@ static void clone_init(struct dm_crypt_io *io, struct bio *clone) clone->bi_destructor = dm_crypt_bio_destructor; } -static void kcryptd_io_read(struct dm_crypt_io *io) +static void kcryptd_unplug(struct crypt_config *cc) +{ + blk_unplug(bdev_get_queue(cc->dev->bdev)); +} + +static int kcryptd_io_read(struct dm_crypt_io *io, gfp_t gfp) { struct crypt_config *cc = io->target->private; struct bio *base_bio = io->base_bio; struct bio *clone; - crypt_inc_pending(io); - /* * The block layer might modify the bvec array, so always * copy the required bvecs because we need the original * one in order to decrypt the whole bio data *afterwards*. */ - clone = bio_alloc_bioset(GFP_NOIO, bio_segments(base_bio), cc->bs); - if (unlikely(!clone)) { - io->error = -ENOMEM; - crypt_dec_pending(io); - return; + clone = bio_alloc_bioset(gfp, bio_segments(base_bio), cc->bs); + if (!clone) { + kcryptd_unplug(cc); + return 1; } + crypt_inc_pending(io); + clone_init(io, clone); clone->bi_idx = 0; clone->bi_vcnt = bio_segments(base_bio); @@ -813,6 +817,7 @@ static void kcryptd_io_read(struct dm_crypt_io *io) sizeof(struct bio_vec) * clone->bi_vcnt); generic_make_request(clone); + return 0; } static void kcryptd_io_write(struct dm_crypt_io *io) @@ -825,9 +830,12 @@ static void kcryptd_io(struct work_struct *work) { struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work); - if (bio_data_dir(io->base_bio) == READ) - kcryptd_io_read(io); - else + if (bio_data_dir(io->base_bio) == READ) { + crypt_inc_pending(io); + if (kcryptd_io_read(io, GFP_NOIO)) + io->error = -ENOMEM; + crypt_dec_pending(io); + } else kcryptd_io_write(io); } @@ -1423,9 +1431,10 @@ static int crypt_map(struct dm_target *ti, struct bio *bio, io = crypt_io_alloc(ti, bio, dm_target_offset(ti, bio->bi_sector)); - if (bio_data_dir(io->base_bio) == READ) - kcryptd_queue_io(io); - else + if (bio_data_dir(io->base_bio) == READ) { + if (kcryptd_io_read(io, GFP_NOWAIT)) + kcryptd_queue_io(io); + } else kcryptd_queue_crypt(io); return DM_MAPIO_SUBMITTED; -- 1.7.4.4