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[PATCH] dm crypt: move io to workqueue

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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 <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Milan Broz 2006-10-03 01:15:39 -07:00 committed by Linus Torvalds
parent 93e605c237
commit 23541d2d28
1 changed files with 28 additions and 37 deletions
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65
drivers/md/dm-crypt.c
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@ -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,