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 #include "dm-snap.h" 10 11 #include <linux/mm.h> 12 #include <linux/pagemap.h> 13 #include <linux/vmalloc.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_destroy(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_snap_exception *e) 41 { 42 struct transient_c *tc = (struct transient_c *) store->context; 43 sector_t size = get_dev_size(store->snap->cow->bdev); 44 45 if (size < (tc->next_free + store->snap->chunk_size)) 46 return -1; 47 48 e->new_chunk = sector_to_chunk(store->snap, tc->next_free); 49 tc->next_free += store->snap->chunk_size; 50 51 return 0; 52 } 53 54 static void transient_commit_exception(struct dm_exception_store *store, 55 struct dm_snap_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_fraction_full(struct dm_exception_store *store, 64 sector_t *numerator, sector_t *denominator) 65 { 66 *numerator = ((struct transient_c *) store->context)->next_free; 67 *denominator = get_dev_size(store->snap->cow->bdev); 68 } 69 70 int dm_create_transient(struct dm_exception_store *store) 71 { 72 struct transient_c *tc; 73 74 store->destroy = transient_destroy; 75 store->read_metadata = transient_read_metadata; 76 store->prepare_exception = transient_prepare_exception; 77 store->commit_exception = transient_commit_exception; 78 store->drop_snapshot = NULL; 79 store->fraction_full = transient_fraction_full; 80 81 tc = kmalloc(sizeof(struct transient_c), GFP_KERNEL); 82 if (!tc) 83 return -ENOMEM; 84 85 tc->next_free = 0; 86 store->context = tc; 87 88 return 0; 89 } 90 91 int dm_transient_snapshot_init(void) 92 { 93 return 0; 94 } 95 96 void dm_transient_snapshot_exit(void) 97 { 98 } 99