dm: add persistent data library
The persistent-data library offers a re-usable framework for the storage
and management of on-disk metadata in device-mapper targets.
It's used by the thin-provisioning target in the next patch and in an
upcoming hierarchical storage target.
For further information, please read
Documentation/device-mapper/persistent-data.txt
Signed-off-by: Joe Thornber <thornber@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/persistent-data/dm-space-map-disk.c b/drivers/md/persistent-data/dm-space-map-disk.c
new file mode 100644
index 0000000..aeff785
--- /dev/null
+++ b/drivers/md/persistent-data/dm-space-map-disk.c
@@ -0,0 +1,335 @@
+/*
+ * Copyright (C) 2011 Red Hat, Inc.
+ *
+ * This file is released under the GPL.
+ */
+
+#include "dm-space-map-checker.h"
+#include "dm-space-map-common.h"
+#include "dm-space-map-disk.h"
+#include "dm-space-map.h"
+#include "dm-transaction-manager.h"
+
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/device-mapper.h>
+
+#define DM_MSG_PREFIX "space map disk"
+
+/*----------------------------------------------------------------*/
+
+/*
+ * Space map interface.
+ */
+struct sm_disk {
+ struct dm_space_map sm;
+
+ struct ll_disk ll;
+ struct ll_disk old_ll;
+
+ dm_block_t begin;
+ dm_block_t nr_allocated_this_transaction;
+};
+
+static void sm_disk_destroy(struct dm_space_map *sm)
+{
+ struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
+
+ kfree(smd);
+}
+
+static int sm_disk_extend(struct dm_space_map *sm, dm_block_t extra_blocks)
+{
+ struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
+
+ return sm_ll_extend(&smd->ll, extra_blocks);
+}
+
+static int sm_disk_get_nr_blocks(struct dm_space_map *sm, dm_block_t *count)
+{
+ struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
+ *count = smd->old_ll.nr_blocks;
+
+ return 0;
+}
+
+static int sm_disk_get_nr_free(struct dm_space_map *sm, dm_block_t *count)
+{
+ struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
+ *count = (smd->old_ll.nr_blocks - smd->old_ll.nr_allocated) - smd->nr_allocated_this_transaction;
+
+ return 0;
+}
+
+static int sm_disk_get_count(struct dm_space_map *sm, dm_block_t b,
+ uint32_t *result)
+{
+ struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
+ return sm_ll_lookup(&smd->ll, b, result);
+}
+
+static int sm_disk_count_is_more_than_one(struct dm_space_map *sm, dm_block_t b,
+ int *result)
+{
+ int r;
+ uint32_t count;
+
+ r = sm_disk_get_count(sm, b, &count);
+ if (r)
+ return r;
+
+ return count > 1;
+}
+
+static int sm_disk_set_count(struct dm_space_map *sm, dm_block_t b,
+ uint32_t count)
+{
+ int r;
+ uint32_t old_count;
+ enum allocation_event ev;
+ struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
+
+ r = sm_ll_insert(&smd->ll, b, count, &ev);
+ if (!r) {
+ switch (ev) {
+ case SM_NONE:
+ break;
+
+ case SM_ALLOC:
+ /*
+ * This _must_ be free in the prior transaction
+ * otherwise we've lost atomicity.
+ */
+ smd->nr_allocated_this_transaction++;
+ break;
+
+ case SM_FREE:
+ /*
+ * It's only free if it's also free in the last
+ * transaction.
+ */
+ r = sm_ll_lookup(&smd->old_ll, b, &old_count);
+ if (r)
+ return r;
+
+ if (!old_count)
+ smd->nr_allocated_this_transaction--;
+ break;
+ }
+ }
+
+ return r;
+}
+
+static int sm_disk_inc_block(struct dm_space_map *sm, dm_block_t b)
+{
+ int r;
+ enum allocation_event ev;
+ struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
+
+ r = sm_ll_inc(&smd->ll, b, &ev);
+ if (!r && (ev == SM_ALLOC))
+ /*
+ * This _must_ be free in the prior transaction
+ * otherwise we've lost atomicity.
+ */
+ smd->nr_allocated_this_transaction++;
+
+ return r;
+}
+
+static int sm_disk_dec_block(struct dm_space_map *sm, dm_block_t b)
+{
+ int r;
+ uint32_t old_count;
+ enum allocation_event ev;
+ struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
+
+ r = sm_ll_dec(&smd->ll, b, &ev);
+ if (!r && (ev == SM_FREE)) {
+ /*
+ * It's only free if it's also free in the last
+ * transaction.
+ */
+ r = sm_ll_lookup(&smd->old_ll, b, &old_count);
+ if (r)
+ return r;
+
+ if (!old_count)
+ smd->nr_allocated_this_transaction--;
+ }
+
+ return r;
+}
+
+static int sm_disk_new_block(struct dm_space_map *sm, dm_block_t *b)
+{
+ int r;
+ enum allocation_event ev;
+ struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
+
+ /* FIXME: we should loop round a couple of times */
+ r = sm_ll_find_free_block(&smd->old_ll, smd->begin, smd->old_ll.nr_blocks, b);
+ if (r)
+ return r;
+
+ smd->begin = *b + 1;
+ r = sm_ll_inc(&smd->ll, *b, &ev);
+ if (!r) {
+ BUG_ON(ev != SM_ALLOC);
+ smd->nr_allocated_this_transaction++;
+ }
+
+ return r;
+}
+
+static int sm_disk_commit(struct dm_space_map *sm)
+{
+ int r;
+ dm_block_t nr_free;
+ struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
+
+ r = sm_disk_get_nr_free(sm, &nr_free);
+ if (r)
+ return r;
+
+ r = sm_ll_commit(&smd->ll);
+ if (r)
+ return r;
+
+ memcpy(&smd->old_ll, &smd->ll, sizeof(smd->old_ll));
+ smd->begin = 0;
+ smd->nr_allocated_this_transaction = 0;
+
+ r = sm_disk_get_nr_free(sm, &nr_free);
+ if (r)
+ return r;
+
+ return 0;
+}
+
+static int sm_disk_root_size(struct dm_space_map *sm, size_t *result)
+{
+ *result = sizeof(struct disk_sm_root);
+
+ return 0;
+}
+
+static int sm_disk_copy_root(struct dm_space_map *sm, void *where_le, size_t max)
+{
+ struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
+ struct disk_sm_root root_le;
+
+ root_le.nr_blocks = cpu_to_le64(smd->ll.nr_blocks);
+ root_le.nr_allocated = cpu_to_le64(smd->ll.nr_allocated);
+ root_le.bitmap_root = cpu_to_le64(smd->ll.bitmap_root);
+ root_le.ref_count_root = cpu_to_le64(smd->ll.ref_count_root);
+
+ if (max < sizeof(root_le))
+ return -ENOSPC;
+
+ memcpy(where_le, &root_le, sizeof(root_le));
+
+ return 0;
+}
+
+/*----------------------------------------------------------------*/
+
+static struct dm_space_map ops = {
+ .destroy = sm_disk_destroy,
+ .extend = sm_disk_extend,
+ .get_nr_blocks = sm_disk_get_nr_blocks,
+ .get_nr_free = sm_disk_get_nr_free,
+ .get_count = sm_disk_get_count,
+ .count_is_more_than_one = sm_disk_count_is_more_than_one,
+ .set_count = sm_disk_set_count,
+ .inc_block = sm_disk_inc_block,
+ .dec_block = sm_disk_dec_block,
+ .new_block = sm_disk_new_block,
+ .commit = sm_disk_commit,
+ .root_size = sm_disk_root_size,
+ .copy_root = sm_disk_copy_root
+};
+
+static struct dm_space_map *dm_sm_disk_create_real(
+ struct dm_transaction_manager *tm,
+ dm_block_t nr_blocks)
+{
+ int r;
+ struct sm_disk *smd;
+
+ smd = kmalloc(sizeof(*smd), GFP_KERNEL);
+ if (!smd)
+ return ERR_PTR(-ENOMEM);
+
+ smd->begin = 0;
+ smd->nr_allocated_this_transaction = 0;
+ memcpy(&smd->sm, &ops, sizeof(smd->sm));
+
+ r = sm_ll_new_disk(&smd->ll, tm);
+ if (r)
+ goto bad;
+
+ r = sm_ll_extend(&smd->ll, nr_blocks);
+ if (r)
+ goto bad;
+
+ r = sm_disk_commit(&smd->sm);
+ if (r)
+ goto bad;
+
+ return &smd->sm;
+
+bad:
+ kfree(smd);
+ return ERR_PTR(r);
+}
+
+struct dm_space_map *dm_sm_disk_create(struct dm_transaction_manager *tm,
+ dm_block_t nr_blocks)
+{
+ struct dm_space_map *sm = dm_sm_disk_create_real(tm, nr_blocks);
+ return dm_sm_checker_create_fresh(sm);
+}
+EXPORT_SYMBOL_GPL(dm_sm_disk_create);
+
+static struct dm_space_map *dm_sm_disk_open_real(
+ struct dm_transaction_manager *tm,
+ void *root_le, size_t len)
+{
+ int r;
+ struct sm_disk *smd;
+
+ smd = kmalloc(sizeof(*smd), GFP_KERNEL);
+ if (!smd)
+ return ERR_PTR(-ENOMEM);
+
+ smd->begin = 0;
+ smd->nr_allocated_this_transaction = 0;
+ memcpy(&smd->sm, &ops, sizeof(smd->sm));
+
+ r = sm_ll_open_disk(&smd->ll, tm, root_le, len);
+ if (r)
+ goto bad;
+
+ r = sm_disk_commit(&smd->sm);
+ if (r)
+ goto bad;
+
+ return &smd->sm;
+
+bad:
+ kfree(smd);
+ return ERR_PTR(r);
+}
+
+struct dm_space_map *dm_sm_disk_open(struct dm_transaction_manager *tm,
+ void *root_le, size_t len)
+{
+ return dm_sm_checker_create(
+ dm_sm_disk_open_real(tm, root_le, len));
+}
+EXPORT_SYMBOL_GPL(dm_sm_disk_open);
+
+/*----------------------------------------------------------------*/