1/* 2 * Copyright (C) 2001-2002 Sistina Software (UK) Limited. 3 * Copyright (C) 2006-2008 Red Hat GmbH 4 * 5 * This file is released under the GPL. 6 */ 7 8#include "dm-exception-store.h" 9 10#include <linux/mm.h> 11#include <linux/pagemap.h> 12#include <linux/vmalloc.h> 13#include <linux/slab.h> 14#include <linux/dm-io.h> 15 16#define DM_MSG_PREFIX "transient snapshot" 17 18/*----------------------------------------------------------------- 19 * Implementation of the store for non-persistent snapshots. 20 *---------------------------------------------------------------*/ 21struct transient_c { 22 sector_t next_free; 23}; 24 25static void transient_dtr(struct dm_exception_store *store) 26{ 27 kfree(store->context); 28} 29 30static int transient_read_metadata(struct dm_exception_store *store, 31 int (*callback)(void *callback_context, 32 chunk_t old, chunk_t new), 33 void *callback_context) 34{ 35 return 0; 36} 37 38static int transient_prepare_exception(struct dm_exception_store *store, 39 struct dm_exception *e) 40{ 41 struct transient_c *tc = store->context; 42 sector_t size = get_dev_size(dm_snap_cow(store->snap)->bdev); 43 44 if (size < (tc->next_free + store->chunk_size)) 45 return -1; 46 47 e->new_chunk = sector_to_chunk(store, tc->next_free); 48 tc->next_free += store->chunk_size; 49 50 return 0; 51} 52 53static void transient_commit_exception(struct dm_exception_store *store, 54 struct dm_exception *e, 55 void (*callback) (void *, int success), 56 void *callback_context) 57{ 58 /* Just succeed */ 59 callback(callback_context, 1); 60} 61 62static void transient_usage(struct dm_exception_store *store, 63 sector_t *total_sectors, 64 sector_t *sectors_allocated, 65 sector_t *metadata_sectors) 66{ 67 *sectors_allocated = ((struct transient_c *) store->context)->next_free; 68 *total_sectors = get_dev_size(dm_snap_cow(store->snap)->bdev); 69 *metadata_sectors = 0; 70} 71 72static int transient_ctr(struct dm_exception_store *store, 73 unsigned argc, char **argv) 74{ 75 struct transient_c *tc; 76 77 tc = kmalloc(sizeof(struct transient_c), GFP_KERNEL); 78 if (!tc) 79 return -ENOMEM; 80 81 tc->next_free = 0; 82 store->context = tc; 83 84 return 0; 85} 86 87static unsigned transient_status(struct dm_exception_store *store, 88 status_type_t status, char *result, 89 unsigned maxlen) 90{ 91 unsigned sz = 0; 92 93 switch (status) { 94 case STATUSTYPE_INFO: 95 break; 96 case STATUSTYPE_TABLE: 97 DMEMIT(" N %llu", (unsigned long long)store->chunk_size); 98 } 99 100 return sz; 101} 102 103static struct dm_exception_store_type _transient_type = { 104 .name = "transient", 105 .module = THIS_MODULE, 106 .ctr = transient_ctr, 107 .dtr = transient_dtr, 108 .read_metadata = transient_read_metadata, 109 .prepare_exception = transient_prepare_exception, 110 .commit_exception = transient_commit_exception, 111 .usage = transient_usage, 112 .status = transient_status, 113}; 114 115static struct dm_exception_store_type _transient_compat_type = { 116 .name = "N", 117 .module = THIS_MODULE, 118 .ctr = transient_ctr, 119 .dtr = transient_dtr, 120 .read_metadata = transient_read_metadata, 121 .prepare_exception = transient_prepare_exception, 122 .commit_exception = transient_commit_exception, 123 .usage = transient_usage, 124 .status = transient_status, 125}; 126 127int dm_transient_snapshot_init(void) 128{ 129 int r; 130 131 r = dm_exception_store_type_register(&_transient_type); 132 if (r) { 133 DMWARN("Unable to register transient exception store type"); 134 return r; 135 } 136 137 r = dm_exception_store_type_register(&_transient_compat_type); 138 if (r) { 139 DMWARN("Unable to register old-style transient " 140 "exception store type"); 141 dm_exception_store_type_unregister(&_transient_type); 142 return r; 143 } 144 145 return r; 146} 147 148void dm_transient_snapshot_exit(void) 149{ 150 dm_exception_store_type_unregister(&_transient_type); 151 dm_exception_store_type_unregister(&_transient_compat_type); 152} 153