dm snapshot: split out exception store implementations
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>
diff --git a/drivers/md/dm-snap-transient.c b/drivers/md/dm-snap-transient.c
new file mode 100644
index 0000000..2a781df
--- /dev/null
+++ b/drivers/md/dm-snap-transient.c
@@ -0,0 +1,95 @@
+/*
+ * 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)
+{
+}