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dm snapshot: split out exception store implementations

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Move the existing snapshot exception store implementations out into
separate files.  Later patches will place these behind a new
interface in preparation for alternative implementations.

Signed-off-by: Alasdair G Kergon <agk@redhat.com>
This commit is contained in:
Alasdair G Kergon
2009-01-06 03:05:17 +00:00
parent 1ae25f9c93
commit 4db6bfe02b
6 changed files with 834 additions and 738 deletions
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95
drivers/md/dm-snap-transient.c Normal file
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/*
* Copyright (C) 2001-2002 Sistina Software (UK) Limited.
* Copyright (C) 2006-2008 Red Hat GmbH
*
* This file is released under the GPL.
*/
#include "dm-exception-store.h"
#include "dm-snap.h"
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/vmalloc.h>
#include <linux/slab.h>
#include <linux/dm-io.h>
#define DM_MSG_PREFIX "transient snapshot"
/*-----------------------------------------------------------------
* Implementation of the store for non-persistent snapshots.
*---------------------------------------------------------------*/
struct transient_c {
sector_t next_free;
};
static void transient_destroy(struct dm_exception_store *store)
{
kfree(store->context);
}
static int transient_read_metadata(struct dm_exception_store *store)
{
return 0;
}
static int transient_prepare(struct dm_exception_store *store,
struct dm_snap_exception *e)
{
struct transient_c *tc = (struct transient_c *) store->context;
sector_t size = get_dev_size(store->snap->cow->bdev);
if (size < (tc->next_free + store->snap->chunk_size))
return -1;
e->new_chunk = sector_to_chunk(store->snap, tc->next_free);
tc->next_free += store->snap->chunk_size;
return 0;
}
static void transient_commit(struct dm_exception_store *store,
struct dm_snap_exception *e,
void (*callback) (void *, int success),
void *callback_context)
{
/* Just succeed */
callback(callback_context, 1);
}
static void transient_fraction_full(struct dm_exception_store *store,
sector_t *numerator, sector_t *denominator)
{
*numerator = ((struct transient_c *) store->context)->next_free;
*denominator = get_dev_size(store->snap->cow->bdev);
}
int dm_create_transient(struct dm_exception_store *store)
{
struct transient_c *tc;
store->destroy = transient_destroy;
store->read_metadata = transient_read_metadata;
store->prepare_exception = transient_prepare;
store->commit_exception = transient_commit;
store->drop_snapshot = NULL;
store->fraction_full = transient_fraction_full;
tc = kmalloc(sizeof(struct transient_c), GFP_KERNEL);
if (!tc)
return -ENOMEM;
tc->next_free = 0;
store->context = tc;
return 0;
}
int dm_transient_snapshot_init(void)
{
return 0;
}
void dm_transient_snapshot_exit(void)
{
}