151 lines
3.6 KiB
C
151 lines
3.6 KiB
C
/*
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* Copyright (C) 2001-2002 Sistina Software (UK) Limited.
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* Copyright (C) 2006-2008 Red Hat GmbH
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*
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* This file is released under the GPL.
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*/
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#include "dm-exception-store.h"
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#include <linux/mm.h>
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#include <linux/pagemap.h>
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#include <linux/vmalloc.h>
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#include <linux/slab.h>
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#include <linux/dm-io.h>
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#define DM_MSG_PREFIX "transient snapshot"
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/*-----------------------------------------------------------------
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* Implementation of the store for non-persistent snapshots.
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*---------------------------------------------------------------*/
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struct transient_c {
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sector_t next_free;
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};
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static void transient_dtr(struct dm_exception_store *store)
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{
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kfree(store->context);
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}
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static int transient_read_metadata(struct dm_exception_store *store,
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int (*callback)(void *callback_context,
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chunk_t old, chunk_t new),
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void *callback_context)
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{
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return 0;
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}
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static int transient_prepare_exception(struct dm_exception_store *store,
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struct dm_snap_exception *e)
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{
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struct transient_c *tc = store->context;
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sector_t size = get_dev_size(store->cow->bdev);
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if (size < (tc->next_free + store->chunk_size))
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return -1;
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e->new_chunk = sector_to_chunk(store, tc->next_free);
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tc->next_free += store->chunk_size;
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return 0;
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}
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static void transient_commit_exception(struct dm_exception_store *store,
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struct dm_snap_exception *e,
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void (*callback) (void *, int success),
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void *callback_context)
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{
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/* Just succeed */
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callback(callback_context, 1);
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}
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static void transient_fraction_full(struct dm_exception_store *store,
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sector_t *numerator, sector_t *denominator)
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{
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*numerator = ((struct transient_c *) store->context)->next_free;
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*denominator = get_dev_size(store->cow->bdev);
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}
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static int transient_ctr(struct dm_exception_store *store,
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unsigned argc, char **argv)
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{
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struct transient_c *tc;
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tc = kmalloc(sizeof(struct transient_c), GFP_KERNEL);
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if (!tc)
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return -ENOMEM;
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tc->next_free = 0;
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store->context = tc;
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return 0;
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}
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static unsigned transient_status(struct dm_exception_store *store,
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status_type_t status, char *result,
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unsigned maxlen)
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{
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unsigned sz = 0;
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switch (status) {
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case STATUSTYPE_INFO:
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break;
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case STATUSTYPE_TABLE:
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DMEMIT(" %s N %llu", store->cow->name,
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(unsigned long long)store->chunk_size);
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}
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return sz;
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}
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static struct dm_exception_store_type _transient_type = {
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.name = "transient",
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.module = THIS_MODULE,
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.ctr = transient_ctr,
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.dtr = transient_dtr,
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.read_metadata = transient_read_metadata,
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.prepare_exception = transient_prepare_exception,
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.commit_exception = transient_commit_exception,
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.fraction_full = transient_fraction_full,
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.status = transient_status,
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};
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static struct dm_exception_store_type _transient_compat_type = {
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.name = "N",
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.module = THIS_MODULE,
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.ctr = transient_ctr,
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.dtr = transient_dtr,
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.read_metadata = transient_read_metadata,
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.prepare_exception = transient_prepare_exception,
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.commit_exception = transient_commit_exception,
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.fraction_full = transient_fraction_full,
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.status = transient_status,
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};
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int dm_transient_snapshot_init(void)
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{
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int r;
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r = dm_exception_store_type_register(&_transient_type);
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if (r) {
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DMWARN("Unable to register transient exception store type");
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return r;
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}
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r = dm_exception_store_type_register(&_transient_compat_type);
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if (r) {
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DMWARN("Unable to register old-style transient "
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"exception store type");
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dm_exception_store_type_unregister(&_transient_type);
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return r;
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}
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return r;
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}
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void dm_transient_snapshot_exit(void)
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{
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dm_exception_store_type_unregister(&_transient_type);
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dm_exception_store_type_unregister(&_transient_compat_type);
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}
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