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Commit 97e7cdf1 authored by Joe Thornber's avatar Joe Thornber Committed by Mike Snitzer
Browse files

dm io: simplify dec_count and sync_io 



Remove the io struct off the stack in sync_io() and allocate it from
the mempool like is done in async_io().

dec_count() now always calls a callback function and always frees the io
struct back to the mempool (so sync_io and async_io share this pattern).

Signed-off-by: default avatarJoe Thornber <ejt@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent 44fa816b

drivers/md/dm-io.c

+42 −35
Original line number Diff line number Diff line
@@ -33,7 +33,6 @@ struct dm_io_client { 
struct io {

	unsigned long error_bits;

	atomic_t count;

	struct completion *wait;

	struct dm_io_client *client;

	io_notify_fn callback;

	void *context;
@@ -112,28 +111,27 @@ static void retrieve_io_and_region_from_bio(struct bio *bio, struct io **io, 
 * We need an io object to keep track of the number of bios that

 * have been dispatched for a particular io.

 *---------------------------------------------------------------*/

static void dec_count(struct io *io, unsigned int region, int error)

static void complete_io(struct io *io)

{

	if (error)

		set_bit(region, &io->error_bits);

	unsigned long error_bits = io->error_bits;

	io_notify_fn fn = io->callback;

	void *context = io->context;



	if (atomic_dec_and_test(&io->count)) {

	if (io->vma_invalidate_size)

		invalidate_kernel_vmap_range(io->vma_invalidate_address,

					     io->vma_invalidate_size);



		if (io->wait)

			complete(io->wait);



		else {

			unsigned long r = io->error_bits;

			io_notify_fn fn = io->callback;

			void *context = io->context;



	mempool_free(io, io->client->pool);

			fn(r, context);

		}

	fn(error_bits, context);

}



static void dec_count(struct io *io, unsigned int region, int error)

{

	if (error)

		set_bit(region, &io->error_bits);



	if (atomic_dec_and_test(&io->count))

		complete_io(io);

}



static void endio(struct bio *bio, int error)
@@ -376,41 +374,51 @@ static void dispatch_io(int rw, unsigned int num_regions, 
	dec_count(io, 0, 0);

}



struct sync_io {

	unsigned long error_bits;

	struct completion wait;

};



static void sync_io_complete(unsigned long error, void *context)

{

	struct sync_io *sio = context;



	sio->error_bits = error;

	complete(&sio->wait);

}



static int sync_io(struct dm_io_client *client, unsigned int num_regions,

		   struct dm_io_region *where, int rw, struct dpages *dp,

		   unsigned long *error_bits)

{

	/*

	 * gcc <= 4.3 can't do the alignment for stack variables, so we must

	 * align it on our own.

	 * volatile prevents the optimizer from removing or reusing

	 * "io_" field from the stack frame (allowed in ANSI C).

	 */

	volatile char io_[sizeof(struct io) + __alignof__(struct io) - 1];

	struct io *io = (struct io *)PTR_ALIGN(&io_, __alignof__(struct io));

	DECLARE_COMPLETION_ONSTACK(wait);

	struct io *io;

	struct sync_io sio;



	if (num_regions > 1 && (rw & RW_MASK) != WRITE) {

		WARN_ON(1);

		return -EIO;

	}



	init_completion(&sio.wait);



	io = mempool_alloc(client->pool, GFP_NOIO);

	io->error_bits = 0;

	atomic_set(&io->count, 1); /* see dispatch_io() */

	io->wait = &wait;

	io->client = client;

	io->callback = sync_io_complete;

	io->context = &sio;



	io->vma_invalidate_address = dp->vma_invalidate_address;

	io->vma_invalidate_size = dp->vma_invalidate_size;



	dispatch_io(rw, num_regions, where, dp, io, 1);



	wait_for_completion_io(&wait);

	wait_for_completion_io(&sio.wait);



	if (error_bits)

		*error_bits = io->error_bits;

		*error_bits = sio.error_bits;



	return io->error_bits ? -EIO : 0;

	return sio.error_bits ? -EIO : 0;

}



static int async_io(struct dm_io_client *client, unsigned int num_regions,
@@ -428,7 +436,6 @@ static int async_io(struct dm_io_client *client, unsigned int num_regions, 
	io = mempool_alloc(client->pool, GFP_NOIO);

	io->error_bits = 0;

	atomic_set(&io->count, 1); /* see dispatch_io() */

	io->wait = NULL;

	io->client = client;

	io->callback = fn;

	io->context = context;
@@ -481,9 +488,9 @@ static int dp_init(struct dm_io_request *io_req, struct dpages *dp, 
 * New collapsed (a)synchronous interface.

 *

 * If the IO is asynchronous (i.e. it has notify.fn), you must either unplug

 * the queue with blk_unplug() some time later or set REQ_SYNC in

io_req->bi_rw. If you fail to do one of these, the IO will be submitted to

 * the disk after q->unplug_delay, which defaults to 3ms in blk-settings.c.

 * the queue with blk_unplug() some time later or set REQ_SYNC in io_req->bi_rw.

 * If you fail to do one of these, the IO will be submitted to the disk after

 * q->unplug_delay, which defaults to 3ms in blk-settings.c.

 */

int dm_io(struct dm_io_request *io_req, unsigned num_regions,

	  struct dm_io_region *where, unsigned long *sync_error_bits)