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/export.h> 14 #include <linux/slab.h> 15 #include <linux/dm-io.h> 16 17 #define DM_MSG_PREFIX "transient snapshot" 18 19 /*----------------------------------------------------------------- 20 * Implementation of the store for non-persistent snapshots. 21 *---------------------------------------------------------------*/ 22 struct transient_c { 23 sector_t next_free; 24 }; 25 26 static void transient_dtr(struct dm_exception_store *store) 27 { 28 kfree(store->context); 29 } 30 31 static int transient_read_metadata(struct dm_exception_store *store, 32 int (*callback)(void *callback_context, 33 chunk_t old, chunk_t new), 34 void *callback_context) 35 { 36 return 0; 37 } 38 39 static int transient_prepare_exception(struct dm_exception_store *store, 40 struct dm_exception *e) 41 { 42 struct transient_c *tc = store->context; 43 sector_t size = get_dev_size(dm_snap_cow(store->snap)->bdev); 44 45 if (size < (tc->next_free + store->chunk_size)) 46 return -1; 47 48 e->new_chunk = sector_to_chunk(store, tc->next_free); 49 tc->next_free += store->chunk_size; 50 51 return 0; 52 } 53 54 static void transient_commit_exception(struct dm_exception_store *store, 55 struct dm_exception *e, 56 void (*callback) (void *, int success), 57 void *callback_context) 58 { 59 /* Just succeed */ 60 callback(callback_context, 1); 61 } 62 63 static void transient_usage(struct dm_exception_store *store, 64 sector_t *total_sectors, 65 sector_t *sectors_allocated, 66 sector_t *metadata_sectors) 67 { 68 *sectors_allocated = ((struct transient_c *) store->context)->next_free; 69 *total_sectors = get_dev_size(dm_snap_cow(store->snap)->bdev); 70 *metadata_sectors = 0; 71 } 72 73 static int transient_ctr(struct dm_exception_store *store, 74 unsigned argc, char **argv) 75 { 76 struct transient_c *tc; 77 78 tc = kmalloc(sizeof(struct transient_c), GFP_KERNEL); 79 if (!tc) 80 return -ENOMEM; 81 82 tc->next_free = 0; 83 store->context = tc; 84 85 return 0; 86 } 87 88 static unsigned transient_status(struct dm_exception_store *store, 89 status_type_t status, char *result, 90 unsigned maxlen) 91 { 92 unsigned sz = 0; 93 94 switch (status) { 95 case STATUSTYPE_INFO: 96 break; 97 case STATUSTYPE_TABLE: 98 DMEMIT(" N %llu", (unsigned long long)store->chunk_size); 99 } 100 101 return sz; 102 } 103 104 static struct dm_exception_store_type _transient_type = { 105 .name = "transient", 106 .module = THIS_MODULE, 107 .ctr = transient_ctr, 108 .dtr = transient_dtr, 109 .read_metadata = transient_read_metadata, 110 .prepare_exception = transient_prepare_exception, 111 .commit_exception = transient_commit_exception, 112 .usage = transient_usage, 113 .status = transient_status, 114 }; 115 116 static struct dm_exception_store_type _transient_compat_type = { 117 .name = "N", 118 .module = THIS_MODULE, 119 .ctr = transient_ctr, 120 .dtr = transient_dtr, 121 .read_metadata = transient_read_metadata, 122 .prepare_exception = transient_prepare_exception, 123 .commit_exception = transient_commit_exception, 124 .usage = transient_usage, 125 .status = transient_status, 126 }; 127 128 int dm_transient_snapshot_init(void) 129 { 130 int r; 131 132 r = dm_exception_store_type_register(&_transient_type); 133 if (r) { 134 DMWARN("Unable to register transient exception store type"); 135 return r; 136 } 137 138 r = dm_exception_store_type_register(&_transient_compat_type); 139 if (r) { 140 DMWARN("Unable to register old-style transient " 141 "exception store type"); 142 dm_exception_store_type_unregister(&_transient_type); 143 return r; 144 } 145 146 return r; 147 } 148 149 void dm_transient_snapshot_exit(void) 150 { 151 dm_exception_store_type_unregister(&_transient_type); 152 dm_exception_store_type_unregister(&_transient_compat_type); 153 } 154