[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 <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
Linus Torvalds
parent
93e605c237
commit
23541d2d28
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@ -35,6 +35,7 @@ struct crypt_io {
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struct work_struct work;
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atomic_t pending;
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int error;
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int post_process;
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};
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/*
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@ -445,8 +446,7 @@ static void dec_pending(struct crypt_io *io, int error)
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* kcryptd:
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*
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* Needed because it would be very unwise to do decryption in an
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* interrupt context, so bios returning from read requests get
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* queued here.
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* interrupt context.
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*/
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static struct workqueue_struct *_kcryptd_workqueue;
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static void kcryptd_do_work(void *data);
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@ -470,12 +470,10 @@ static int crypt_endio(struct bio *clone, unsigned int done, int error)
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if (!read_io)
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crypt_free_buffer_pages(cc, clone, done);
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/* keep going - not finished yet */
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if (unlikely(clone->bi_size))
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return 1;
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/*
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* successful reads are decrypted by the worker thread
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*/
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if (!read_io)
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goto out;
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@ -485,6 +483,7 @@ static int crypt_endio(struct bio *clone, unsigned int done, int error)
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}
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bio_put(clone);
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io->post_process = 1;
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kcryptd_queue_io(io);
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return 0;
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@ -504,7 +503,7 @@ static void clone_init(struct crypt_io *io, struct bio *clone)
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clone->bi_rw = io->base_bio->bi_rw;
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}
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static int process_read(struct crypt_io *io)
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static void process_read(struct crypt_io *io)
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{
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struct crypt_config *cc = io->target->private;
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struct bio *base_bio = io->base_bio;
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@ -521,7 +520,7 @@ static int process_read(struct crypt_io *io)
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clone = bio_alloc(GFP_NOIO, bio_segments(base_bio));
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if (unlikely(!clone)) {
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dec_pending(io, -ENOMEM);
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return 0;
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return;
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}
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clone_init(io, clone);
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@ -533,11 +532,9 @@ static int process_read(struct crypt_io *io)
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sizeof(struct bio_vec) * clone->bi_vcnt);
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generic_make_request(clone);
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return 0;
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}
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static int process_write(struct crypt_io *io)
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static void process_write(struct crypt_io *io)
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{
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struct crypt_config *cc = io->target->private;
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struct bio *base_bio = io->base_bio;
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@ -558,15 +555,18 @@ static int process_write(struct crypt_io *io)
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while (remaining) {
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clone = crypt_alloc_buffer(cc, base_bio->bi_size,
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io->first_clone, &bvec_idx);
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if (unlikely(!clone))
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goto cleanup;
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if (unlikely(!clone)) {
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dec_pending(io, -ENOMEM);
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return;
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}
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ctx.bio_out = clone;
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if (unlikely(crypt_convert(cc, &ctx) < 0)) {
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crypt_free_buffer_pages(cc, clone, clone->bi_size);
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bio_put(clone);
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goto cleanup;
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dec_pending(io, -EIO);
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return;
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}
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clone_init(io, clone);
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@ -582,31 +582,20 @@ static int process_write(struct crypt_io *io)
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io->first_clone = clone;
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}
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atomic_inc(&io->pending);
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remaining -= clone->bi_size;
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sector += bio_sectors(clone);
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/* prevent bio_put of first_clone */
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if (remaining)
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atomic_inc(&io->pending);
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generic_make_request(clone);
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/* out of memory -> run queues */
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if (remaining)
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blk_congestion_wait(bio_data_dir(clone), HZ/100);
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}
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/* drop reference, clones could have returned before we reach this */
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dec_pending(io, 0);
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return 0;
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cleanup:
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if (io->first_clone) {
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dec_pending(io, -ENOMEM);
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return 0;
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}
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/* if no bio has been dispatched yet, we can directly return the error */
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mempool_free(io, cc->io_pool);
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return -ENOMEM;
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}
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static void process_read_endio(struct crypt_io *io)
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@ -624,7 +613,12 @@ static void kcryptd_do_work(void *data)
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{
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struct crypt_io *io = data;
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process_read_endio(io);
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if (io->post_process)
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process_read_endio(io);
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else if (bio_data_dir(io->base_bio) == READ)
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process_read(io);
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else
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process_write(io);
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}
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/*
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@ -889,17 +883,14 @@ static int crypt_map(struct dm_target *ti, struct bio *bio,
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struct crypt_io *io;
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io = mempool_alloc(cc->io_pool, GFP_NOIO);
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io->target = ti;
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io->base_bio = bio;
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io->first_clone = NULL;
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io->error = 0;
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io->error = io->post_process = 0;
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atomic_set(&io->pending, 0);
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kcryptd_queue_io(io);
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if (bio_data_dir(bio) == WRITE)
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return process_write(io);
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return process_read(io);
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return 0;
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}
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static int crypt_status(struct dm_target *ti, status_type_t type,
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@ -999,7 +990,7 @@ error:
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static struct target_type crypt_target = {
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.name = "crypt",
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.version= {1, 2, 0},
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.version= {1, 3, 0},
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.module = THIS_MODULE,
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.ctr = crypt_ctr,
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.dtr = crypt_dtr,
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