14db6bfe0SAlasdair G Kergon /* 24db6bfe0SAlasdair G Kergon * Copyright (C) 2001-2002 Sistina Software (UK) Limited. 34db6bfe0SAlasdair G Kergon * Copyright (C) 2006-2008 Red Hat GmbH 44db6bfe0SAlasdair G Kergon * 54db6bfe0SAlasdair G Kergon * This file is released under the GPL. 64db6bfe0SAlasdair G Kergon */ 74db6bfe0SAlasdair G Kergon 84db6bfe0SAlasdair G Kergon #include "dm-exception-store.h" 94db6bfe0SAlasdair G Kergon #include "dm-snap.h" 104db6bfe0SAlasdair G Kergon 114db6bfe0SAlasdair G Kergon #include <linux/mm.h> 124db6bfe0SAlasdair G Kergon #include <linux/pagemap.h> 134db6bfe0SAlasdair G Kergon #include <linux/vmalloc.h> 144db6bfe0SAlasdair G Kergon #include <linux/slab.h> 154db6bfe0SAlasdair G Kergon #include <linux/dm-io.h> 164db6bfe0SAlasdair G Kergon 174db6bfe0SAlasdair G Kergon #define DM_MSG_PREFIX "transient snapshot" 184db6bfe0SAlasdair G Kergon 194db6bfe0SAlasdair G Kergon /*----------------------------------------------------------------- 204db6bfe0SAlasdair G Kergon * Implementation of the store for non-persistent snapshots. 214db6bfe0SAlasdair G Kergon *---------------------------------------------------------------*/ 224db6bfe0SAlasdair G Kergon struct transient_c { 234db6bfe0SAlasdair G Kergon sector_t next_free; 244db6bfe0SAlasdair G Kergon }; 254db6bfe0SAlasdair G Kergon 264db6bfe0SAlasdair G Kergon static void transient_destroy(struct dm_exception_store *store) 274db6bfe0SAlasdair G Kergon { 284db6bfe0SAlasdair G Kergon kfree(store->context); 294db6bfe0SAlasdair G Kergon } 304db6bfe0SAlasdair G Kergon 314db6bfe0SAlasdair G Kergon static int transient_read_metadata(struct dm_exception_store *store) 324db6bfe0SAlasdair G Kergon { 334db6bfe0SAlasdair G Kergon return 0; 344db6bfe0SAlasdair G Kergon } 354db6bfe0SAlasdair G Kergon 364db6bfe0SAlasdair G Kergon static int transient_prepare(struct dm_exception_store *store, 374db6bfe0SAlasdair G Kergon struct dm_snap_exception *e) 384db6bfe0SAlasdair G Kergon { 394db6bfe0SAlasdair G Kergon struct transient_c *tc = (struct transient_c *) store->context; 404db6bfe0SAlasdair G Kergon sector_t size = get_dev_size(store->snap->cow->bdev); 414db6bfe0SAlasdair G Kergon 424db6bfe0SAlasdair G Kergon if (size < (tc->next_free + store->snap->chunk_size)) 434db6bfe0SAlasdair G Kergon return -1; 444db6bfe0SAlasdair G Kergon 454db6bfe0SAlasdair G Kergon e->new_chunk = sector_to_chunk(store->snap, tc->next_free); 464db6bfe0SAlasdair G Kergon tc->next_free += store->snap->chunk_size; 474db6bfe0SAlasdair G Kergon 484db6bfe0SAlasdair G Kergon return 0; 494db6bfe0SAlasdair G Kergon } 504db6bfe0SAlasdair G Kergon 514db6bfe0SAlasdair G Kergon static void transient_commit(struct dm_exception_store *store, 524db6bfe0SAlasdair G Kergon struct dm_snap_exception *e, 534db6bfe0SAlasdair G Kergon void (*callback) (void *, int success), 544db6bfe0SAlasdair G Kergon void *callback_context) 554db6bfe0SAlasdair G Kergon { 564db6bfe0SAlasdair G Kergon /* Just succeed */ 574db6bfe0SAlasdair G Kergon callback(callback_context, 1); 584db6bfe0SAlasdair G Kergon } 594db6bfe0SAlasdair G Kergon 604db6bfe0SAlasdair G Kergon static void transient_fraction_full(struct dm_exception_store *store, 614db6bfe0SAlasdair G Kergon sector_t *numerator, sector_t *denominator) 624db6bfe0SAlasdair G Kergon { 634db6bfe0SAlasdair G Kergon *numerator = ((struct transient_c *) store->context)->next_free; 644db6bfe0SAlasdair G Kergon *denominator = get_dev_size(store->snap->cow->bdev); 654db6bfe0SAlasdair G Kergon } 664db6bfe0SAlasdair G Kergon 674db6bfe0SAlasdair G Kergon int dm_create_transient(struct dm_exception_store *store) 684db6bfe0SAlasdair G Kergon { 694db6bfe0SAlasdair G Kergon struct transient_c *tc; 704db6bfe0SAlasdair G Kergon 714db6bfe0SAlasdair G Kergon store->destroy = transient_destroy; 724db6bfe0SAlasdair G Kergon store->read_metadata = transient_read_metadata; 734db6bfe0SAlasdair G Kergon store->prepare_exception = transient_prepare; 744db6bfe0SAlasdair G Kergon store->commit_exception = transient_commit; 754db6bfe0SAlasdair G Kergon store->drop_snapshot = NULL; 764db6bfe0SAlasdair G Kergon store->fraction_full = transient_fraction_full; 774db6bfe0SAlasdair G Kergon 784db6bfe0SAlasdair G Kergon tc = kmalloc(sizeof(struct transient_c), GFP_KERNEL); 794db6bfe0SAlasdair G Kergon if (!tc) 804db6bfe0SAlasdair G Kergon return -ENOMEM; 814db6bfe0SAlasdair G Kergon 824db6bfe0SAlasdair G Kergon tc->next_free = 0; 834db6bfe0SAlasdair G Kergon store->context = tc; 844db6bfe0SAlasdair G Kergon 854db6bfe0SAlasdair G Kergon return 0; 864db6bfe0SAlasdair G Kergon } 874db6bfe0SAlasdair G Kergon 884db6bfe0SAlasdair G Kergon int dm_transient_snapshot_init(void) 894db6bfe0SAlasdair G Kergon { 904db6bfe0SAlasdair G Kergon return 0; 914db6bfe0SAlasdair G Kergon } 924db6bfe0SAlasdair G Kergon 934db6bfe0SAlasdair G Kergon void dm_transient_snapshot_exit(void) 944db6bfe0SAlasdair G Kergon { 954db6bfe0SAlasdair G Kergon } 96