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dm snapshot: use dm-bufio

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

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Mikulas Patocka 2014-01-13 19:12:36 -05:00 committed by Mike Snitzer
parent 2cadabd512
commit 55494bf294
4 changed files with 62 additions and 7 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

1
drivers/md/Kconfig
View file

@ -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.

22
drivers/md/dm-bufio.c
View file

@ -1350,6 +1350,28 @@ void dm_bufio_release_move(struct dm_buffer *b, sector_t new_block)
}
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;

7
drivers/md/dm-bufio.h
View file

@ -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);

39
drivers/md/dm-snap-persistent.c
View file

@ -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);
r = insert_exceptions(ps, ps->area, callback, callback_context,
area = dm_bufio_read(client, chunk, &bp);
if (unlikely(IS_ERR(area))) {
r = PTR_ERR(area);
goto ret_destroy_bufio;
}
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)