LXR linux/drivers/md/dm-snap-transient.c

   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 *---------------------------------------------------------------*/
  22struct transient_c {
  23        sector_t next_free;
  24};
  25
  26static void transient_dtr(struct dm_exception_store *store)
  27{
  28        kfree(store->context);
  29}
  30
  31static 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
  39static 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
  54static 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
  63static 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
  73static 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
  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