From aea53d92f70eeb00ae480e399a997dd55fd5055d Mon Sep 17 00:00:00 2001 From: Jonathan Brassow Date: Tue, 6 Jan 2009 03:05:15 +0000 Subject: dm snapshot: separate out exception store interface Pull structures that bridge the gap between snapshot and exception store out of dm-snap.h and put them in a new .h file - dm-exception-store.h. This file will define the API for new exception stores. Ultimately, dm-snap.h is unnecessary, since only dm-snap.c should be using it. Signed-off-by: Jonathan Brassow Signed-off-by: Alasdair G Kergon --- drivers/md/dm-snap.h | 121 +-------------------------------------------------- 1 file changed, 1 insertion(+), 120 deletions(-) (limited to 'drivers/md/dm-snap.h') diff --git a/drivers/md/dm-snap.h b/drivers/md/dm-snap.h index 99c0106ede2d..6e4beaf89f6c 100644 --- a/drivers/md/dm-snap.h +++ b/drivers/md/dm-snap.h @@ -1,6 +1,4 @@ /* - * dm-snapshot.c - * * Copyright (C) 2001-2002 Sistina Software (UK) Limited. * * This file is released under the GPL. @@ -10,6 +8,7 @@ #define DM_SNAPSHOT_H #include +#include "dm-exception-store.h" #include "dm-bio-list.h" #include #include @@ -20,116 +19,6 @@ struct exception_table { struct list_head *table; }; -/* - * The snapshot code deals with largish chunks of the disk at a - * time. Typically 32k - 512k. - */ -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 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). - */ -struct exception_store { - - /* - * Destroys this object when you've finished with it. - */ - void (*destroy) (struct exception_store *store); - - /* - * The target shouldn't read the COW device until this is - * called. - */ - int (*read_metadata) (struct exception_store *store); - - /* - * Find somewhere to store the next exception. - */ - int (*prepare_exception) (struct exception_store *store, - struct dm_snap_exception *e); - - /* - * Update the metadata with this exception. - */ - void (*commit_exception) (struct exception_store *store, - struct dm_snap_exception *e, - void (*callback) (void *, int success), - void *callback_context); - - /* - * The snapshot is invalid, note this in the metadata. - */ - void (*drop_snapshot) (struct exception_store *store); - - /* - * Return how full the snapshot is. - */ - void (*fraction_full) (struct exception_store *store, - sector_t *numerator, - sector_t *denominator); - - struct dm_snapshot *snap; - void *context; -}; - #define DM_TRACKED_CHUNK_HASH_SIZE 16 #define DM_TRACKED_CHUNK_HASH(x) ((unsigned long)(x) & \ (DM_TRACKED_CHUNK_HASH_SIZE - 1)) @@ -192,14 +81,6 @@ struct dm_snapshot { */ int dm_add_exception(struct dm_snapshot *s, chunk_t old, chunk_t new); -/* - * Constructor and destructor for the default persistent - * store. - */ -int dm_create_persistent(struct exception_store *store); - -int dm_create_transient(struct exception_store *store); - /* * Return the number of sectors in the device. */ -- cgit 1.4.1