#define DM_SNAPSHOT_H
#include "dm.h"
+#include "dm-bio-list.h"
#include <linux/blkdev.h>
+#include <linux/workqueue.h>
struct exception_table {
uint32_t hash_mask;
+ unsigned hash_shift;
struct list_head *table;
};
/*
* The snapshot code deals with largish chunks of the disk at a
- * time. Typically 64k - 256k.
+ * time. Typically 32k - 512k.
*/
-/* FIXME: can we get away with limiting these to a uint32_t ? */
typedef sector_t chunk_t;
/*
* An exception is used where an old chunk of data has been
* replaced by a new one.
+ * If chunk_t is 64 bits in size, the top 8 bits of new_chunk hold the number
+ * of chunks that follow contiguously. Remaining bits hold the number of the
+ * chunk within the device.
*/
-struct exception {
+struct dm_snap_exception {
struct list_head hash_list;
chunk_t old_chunk;
chunk_t new_chunk;
};
+/*
+ * Funtions to manipulate consecutive chunks
+ */
+# if defined(CONFIG_LBD) || (BITS_PER_LONG == 64)
+# define DM_CHUNK_CONSECUTIVE_BITS 8
+# define DM_CHUNK_NUMBER_BITS 56
+
+static inline chunk_t dm_chunk_number(chunk_t chunk)
+{
+ return chunk & (chunk_t)((1ULL << DM_CHUNK_NUMBER_BITS) - 1ULL);
+}
+
+static inline unsigned dm_consecutive_chunk_count(struct dm_snap_exception *e)
+{
+ return e->new_chunk >> DM_CHUNK_NUMBER_BITS;
+}
+
+static inline void dm_consecutive_chunk_count_inc(struct dm_snap_exception *e)
+{
+ e->new_chunk += (1ULL << DM_CHUNK_NUMBER_BITS);
+
+ BUG_ON(!dm_consecutive_chunk_count(e));
+}
+
+# else
+# define DM_CHUNK_CONSECUTIVE_BITS 0
+
+static inline chunk_t dm_chunk_number(chunk_t chunk)
+{
+ return chunk;
+}
+
+static inline unsigned dm_consecutive_chunk_count(struct dm_snap_exception *e)
+{
+ return 0;
+}
+
+static inline void dm_consecutive_chunk_count_inc(struct dm_snap_exception *e)
+{
+}
+
+# endif
+
/*
* Abstraction to handle the meta/layout of exception stores (the
* COW device).
* Find somewhere to store the next exception.
*/
int (*prepare_exception) (struct exception_store *store,
- struct exception *e);
+ struct dm_snap_exception *e);
/*
* Update the metadata with this exception.
*/
void (*commit_exception) (struct exception_store *store,
- struct exception *e,
+ struct dm_snap_exception *e,
void (*callback) (void *, int success),
void *callback_context);
struct dm_snapshot {
struct rw_semaphore lock;
- struct dm_table *table;
+ struct dm_target *ti;
struct dm_dev *origin;
struct dm_dev *cow;
struct exception_table pending;
struct exception_table complete;
+ /*
+ * pe_lock protects all pending_exception operations and access
+ * as well as the snapshot_bios list.
+ */
+ spinlock_t pe_lock;
+
/* The on disk metadata handler */
struct exception_store store;
- struct kcopyd_client *kcopyd_client;
+ struct dm_kcopyd_client *kcopyd_client;
+
+ /* Queue of snapshot writes for ksnapd to flush */
+ struct bio_list queued_bios;
+ struct work_struct queued_bios_work;
};
/*
* Constructor and destructor for the default persistent
* store.
*/
-int dm_create_persistent(struct exception_store *store, uint32_t chunk_size);
+int dm_create_persistent(struct exception_store *store);
-int dm_create_transient(struct exception_store *store,
- struct dm_snapshot *s, int blocksize);
+int dm_create_transient(struct exception_store *store);
/*
* Return the number of sectors in the device.