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authorMilan Broz <mbroz@redhat.com>2011-01-13 20:59:53 +0100
committerAlasdair G Kergon <agk@redhat.com>2011-01-13 20:59:53 +0100
commit20c82538e4f5ede51bc2b4795bc6e5cae772796d (patch)
treea70248a06b21bf249382d6f6beac4b8681bf8f35
parentdm crypt: scale to multiple cpus (diff)
downloadlinux-20c82538e4f5ede51bc2b4795bc6e5cae772796d.tar.xz
linux-20c82538e4f5ede51bc2b4795bc6e5cae772796d.zip
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 <mbroz@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
-rw-r--r--drivers/md/dm-crypt.c37
1 files changed, 23 insertions, 14 deletions
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 50ae6ef83738..dc4403bcc6a0 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -787,26 +787,30 @@ 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);
@@ -816,6 +820,7 @@ 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)
@@ -828,9 +833,12 @@ 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);
}
@@ -1424,9 +1432,10 @@ 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;