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Commit 55494bf2 authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Mike Snitzer
Browse files

dm snapshot: use dm-bufio 



Use dm-bufio for initial loading of the exceptions.
Introduce a new function dm_bufio_forget that frees the given buffer.

Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent 2cadabd5

drivers/md/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -238,6 +238,7 @@ config DM_CRYPT 
config DM_SNAPSHOT

       tristate "Snapshot target"

       depends on BLK_DEV_DM

       select DM_BUFIO

       ---help---

         Allow volume managers to take writable snapshots of a device.

drivers/md/dm-bufio.c

+22 −0
Original line number Diff line number Diff line
@@ -1350,6 +1350,28 @@ retry: 
}

EXPORT_SYMBOL_GPL(dm_bufio_release_move);



/*

 * Free the given buffer.

 *

 * This is just a hint, if the buffer is in use or dirty, this function

 * does nothing.

 */

void dm_bufio_forget(struct dm_bufio_client *c, sector_t block)

{

	struct dm_buffer *b;



	dm_bufio_lock(c);



	b = __find(c, block);

	if (b && likely(!b->hold_count) && likely(!b->state)) {

		__unlink_buffer(b);

		__free_buffer_wake(b);

	}



	dm_bufio_unlock(c);

}

EXPORT_SYMBOL(dm_bufio_forget);



unsigned dm_bufio_get_block_size(struct dm_bufio_client *c)

{

	return c->block_size;

drivers/md/dm-bufio.h

+7 −0
Original line number Diff line number Diff line
@@ -108,6 +108,13 @@ int dm_bufio_issue_flush(struct dm_bufio_client *c); 
 */

void dm_bufio_release_move(struct dm_buffer *b, sector_t new_block);



/*

 * Free the given buffer.

 * This is just a hint, if the buffer is in use or dirty, this function

 * does nothing.

 */

void dm_bufio_forget(struct dm_bufio_client *c, sector_t block);



unsigned dm_bufio_get_block_size(struct dm_bufio_client *c);

sector_t dm_bufio_get_device_size(struct dm_bufio_client *c);

sector_t dm_bufio_get_block_number(struct dm_buffer *b);

drivers/md/dm-snap-persistent.c

+32 −7
Original line number Diff line number Diff line
@@ -13,6 +13,7 @@ 
#include <linux/export.h>

#include <linux/slab.h>

#include <linux/dm-io.h>

#include "dm-bufio.h"



#define DM_MSG_PREFIX "persistent snapshot"

#define DM_CHUNK_SIZE_DEFAULT_SECTORS 32	/* 16KB */
@@ -495,27 +496,51 @@ static int read_exceptions(struct pstore *ps, 
			   void *callback_context)

{

	int r, full = 1;

	struct dm_bufio_client *client;



	client = dm_bufio_client_create(dm_snap_cow(ps->store->snap)->bdev,

					ps->store->chunk_size << SECTOR_SHIFT,

					1, 0, NULL, NULL);



	if (IS_ERR(client))

		return PTR_ERR(client);



	/*

	 * Keeping reading chunks and inserting exceptions until

	 * we find a partially full area.

	 */

	for (ps->current_area = 0; full; ps->current_area++) {

		r = area_io(ps, READ);

		if (r)

			return r;

		struct dm_buffer *bp;

		void *area;

		chunk_t chunk = area_location(ps, ps->current_area);



		area = dm_bufio_read(client, chunk, &bp);

		if (unlikely(IS_ERR(area))) {

			r = PTR_ERR(area);

			goto ret_destroy_bufio;

		}



		r = insert_exceptions(ps, ps->area, callback, callback_context,

		r = insert_exceptions(ps, area, callback, callback_context,

				      &full);

		if (r)

			return r;



		dm_bufio_release(bp);



		dm_bufio_forget(client, chunk);



		if (unlikely(r))

			goto ret_destroy_bufio;

	}



	ps->current_area--;



	skip_metadata(ps);



	return 0;

	r = 0;



ret_destroy_bufio:

	dm_bufio_client_destroy(client);



	return r;

}



static struct pstore *get_info(struct dm_exception_store *store)