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, int valid, 56 void (*callback) (void *, int success), 57 void *callback_context) 58 { 59 /* Just succeed */ 60 callback(callback_context, valid); 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, char *options) 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 87 static 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 break; 99 case STATUSTYPE_IMA: 100 *result = '\0'; 101 break; 102 } 103 104 return sz; 105 } 106 107 static struct dm_exception_store_type _transient_type = { 108 .name = "transient", 109 .module = THIS_MODULE, 110 .ctr = transient_ctr, 111 .dtr = transient_dtr, 112 .read_metadata = transient_read_metadata, 113 .prepare_exception = transient_prepare_exception, 114 .commit_exception = transient_commit_exception, 115 .usage = transient_usage, 116 .status = transient_status, 117 }; 118 119 static struct dm_exception_store_type _transient_compat_type = { 120 .name = "N", 121 .module = THIS_MODULE, 122 .ctr = transient_ctr, 123 .dtr = transient_dtr, 124 .read_metadata = transient_read_metadata, 125 .prepare_exception = transient_prepare_exception, 126 .commit_exception = transient_commit_exception, 127 .usage = transient_usage, 128 .status = transient_status, 129 }; 130 131 int dm_transient_snapshot_init(void) 132 { 133 int r; 134 135 r = dm_exception_store_type_register(&_transient_type); 136 if (r) { 137 DMWARN("Unable to register transient exception store type"); 138 return r; 139 } 140 141 r = dm_exception_store_type_register(&_transient_compat_type); 142 if (r) { 143 DMWARN("Unable to register old-style transient " 144 "exception store type"); 145 dm_exception_store_type_unregister(&_transient_type); 146 return r; 147 } 148 149 return r; 150 } 151 152 void dm_transient_snapshot_exit(void) 153 { 154 dm_exception_store_type_unregister(&_transient_type); 155 dm_exception_store_type_unregister(&_transient_compat_type); 156 } 157