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>
--- /dev/null
+Introduction
+============
+
+The more-sophisticated device-mapper targets require complex metadata
+that is managed in kernel. In late 2010 we were seeing that various
+different targets were rolling their own data strutures, for example:
+
+- Mikulas Patocka's multisnap implementation
+- Heinz Mauelshagen's thin provisioning target
+- Another btree-based caching target posted to dm-devel
+- Another multi-snapshot target based on a design of Daniel Phillips
+
+Maintaining these data structures takes a lot of work, so if possible
+we'd like to reduce the number.
+
+The persistent-data library is an attempt to provide a re-usable
+framework for people who want to store metadata in device-mapper
+targets. It's currently used by the thin-provisioning target and an
+upcoming hierarchical storage target.
+
+Overview
+========
+
+The main documentation is in the header files which can all be found
+under drivers/md/persistent-data.
+
+The block manager
+-----------------
+
+dm-block-manager.[hc]
+
+This provides access to the data on disk in fixed sized-blocks. There
+is a read/write locking interface to prevent concurrent accesses, and
+keep data that is being used in the cache.
+
+Clients of persistent-data are unlikely to use this directly.
+
+The transaction manager
+-----------------------
+
+dm-transaction-manager.[hc]
+
+This restricts access to blocks and enforces copy-on-write semantics.
+The only way you can get hold of a writable block through the
+transaction manager is by shadowing an existing block (ie. doing
+copy-on-write) or allocating a fresh one. Shadowing is elided within
+the same transaction so performance is reasonable. The commit method
+ensures that all data is flushed before it writes the superblock.
+On power failure your metadata will be as it was when last committed.
+
+The Space Maps
+--------------
+
+dm-space-map.h
+dm-space-map-metadata.[hc]
+dm-space-map-disk.[hc]
+
+On-disk data structures that keep track of reference counts of blocks.
+Also acts as the allocator of new blocks. Currently two
+implementations: a simpler one for managing blocks on a different
+device (eg. thinly-provisioned data blocks); and one for managing
+the metadata space. The latter is complicated by the need to store
+its own data within the space it's managing.
+
+The data structures
+-------------------
+
+dm-btree.[hc]
+dm-btree-remove.c
+dm-btree-spine.c
+dm-btree-internal.h
+
+Currently there is only one data structure, a hierarchical btree.
+There are plans to add more. For example, something with an
+array-like interface would see a lot of use.
+
+The btree is 'hierarchical' in that you can define it to be composed
+of nested btrees, and take multiple keys. For example, the
+thin-provisioning target uses a btree with two levels of nesting.
+The first maps a device id to a mapping tree, and that in turn maps a
+virtual block to a physical block.
+
+Values stored in the btrees can have arbitrary size. Keys are always
+64bits, although nesting allows you to use multiple keys.
--- /dev/null
+config DM_PERSISTENT_DATA
+ tristate "Persistent data library (EXPERIMENTAL)"
+ depends on BLK_DEV_DM && EXPERIMENTAL
+ select LIBCRC32C
+ ---help---
+ Library providing immutable on-disk data structure support for
+ device-mapper targets such as the thin provisioning target.
--- /dev/null
+obj-$(CONFIG_DM_PERSISTENT_DATA) += dm-persistent-data.o
+dm-persistent-data-objs := \
+ dm-block-manager.o \
+ dm-space-map-disk.o \
+ dm-space-map-metadata.o \
+ dm-transaction-manager.o \
+ dm-btree.o \
+ dm-btree-remove.o \
+ dm-btree-spine.o
--- /dev/null
+/*
+ * Copyright (C) 2011 Red Hat, Inc. All rights reserved.
+ *
+ * This file is released under the GPL.
+ */
+#include "dm-block-manager.h"
+
+#include <linux/dm-io.h>
+#include <linux/slab.h>
+#include <linux/device-mapper.h> /* For SECTOR_SHIFT and DMERR */
+
+#define DM_MSG_PREFIX "block manager"
+
+/*----------------------------------------------------------------*/
+
+#define SECTOR_SIZE 512
+
+enum dm_block_state {
+ BS_EMPTY,
+ BS_CLEAN,
+ BS_READING,
+ BS_WRITING,
+ BS_READ_LOCKED,
+ BS_READ_LOCKED_DIRTY, /* block was dirty before it was read locked */
+ BS_WRITE_LOCKED,
+ BS_DIRTY,
+ BS_ERROR
+};
+
+struct dm_block {
+ struct list_head list;
+ struct hlist_node hlist;
+
+ dm_block_t where;
+ struct dm_block_validator *validator;
+ void *data_actual;
+ void *data;
+ wait_queue_head_t io_q;
+ unsigned read_lock_count;
+ unsigned write_lock_pending;
+ enum dm_block_state state;
+
+ /* Extra flags like REQ_FLUSH and REQ_FUA can be set here. This is
+ * mainly as to avoid a race condition in flush_and_unlock() where
+ * the newly unlocked superblock may have been submitted for a
+ * write before the write_all_dirty() call is made.
+ */
+ int io_flags;
+
+ /*
+ * Sadly we need an up pointer so we can get to the bm on io
+ * completion.
+ */
+ struct dm_block_manager *bm;
+};
+
+struct dm_block_manager {
+ struct block_device *bdev;
+ unsigned cache_size; /* in bytes */
+ unsigned block_size; /* in bytes */
+ dm_block_t nr_blocks;
+
+ /* this will trigger everytime an io completes */
+ wait_queue_head_t io_q;
+
+ struct dm_io_client *io;
+
+ /* |lock| protects all the lists and the hash table */
+ spinlock_t lock;
+ struct list_head empty_list; /* no block assigned */
+ struct list_head clean_list; /* unlocked and clean */
+ struct list_head dirty_list; /* unlocked and dirty */
+ struct list_head error_list;
+ unsigned available_count;
+ unsigned reading_count;
+ unsigned writing_count;
+
+ /*
+ * Hash table of cached blocks, holds everything that isn't in the
+ * BS_EMPTY state.
+ */
+ unsigned hash_size;
+ unsigned hash_mask;
+ struct hlist_head buckets[0]; /* must be last member of struct */
+};
+
+dm_block_t dm_block_location(struct dm_block *b)
+{
+ return b->where;
+}
+EXPORT_SYMBOL_GPL(dm_block_location);
+
+void *dm_block_data(struct dm_block *b)
+{
+ return b->data;
+}
+EXPORT_SYMBOL_GPL(dm_block_data);
+
+/*----------------------------------------------------------------
+ * Hash table
+ *--------------------------------------------------------------*/
+static unsigned hash_block(struct dm_block_manager *bm, dm_block_t b)
+{
+ const unsigned BIG_PRIME = 4294967291UL;
+
+ return (((unsigned) b) * BIG_PRIME) & bm->hash_mask;
+}
+
+static struct dm_block *__find_block(struct dm_block_manager *bm, dm_block_t b)
+{
+ unsigned bucket = hash_block(bm, b);
+ struct dm_block *blk;
+ struct hlist_node *n;
+
+ hlist_for_each_entry(blk, n, bm->buckets + bucket, hlist)
+ if (blk->where == b)
+ return blk;
+
+ return NULL;
+}
+
+static void __insert_block(struct dm_block_manager *bm, struct dm_block *b)
+{
+ unsigned bucket = hash_block(bm, b->where);
+
+ hlist_add_head(&b->hlist, bm->buckets + bucket);
+}
+
+/*----------------------------------------------------------------
+ * Block state:
+ * __transition() handles transition of a block between different states.
+ * Study this to understand the state machine.
+ *
+ * Alternatively install graphviz and run:
+ * grep DOT dm-block-manager.c | grep -v ' ' |
+ * sed -e 's/.*DOT: //' -e 's/\*\///' |
+ * dot -Tps -o states.ps
+ *
+ * Assumes bm->lock is held.
+ *--------------------------------------------------------------*/
+static void __transition(struct dm_block *b, enum dm_block_state new_state)
+{
+ /* DOT: digraph BlockStates { */
+ struct dm_block_manager *bm = b->bm;
+
+ switch (new_state) {
+ case BS_EMPTY:
+ /* DOT: error -> empty */
+ /* DOT: clean -> empty */
+ BUG_ON(!((b->state == BS_ERROR) ||
+ (b->state == BS_CLEAN)));
+ hlist_del(&b->hlist);
+ list_move(&b->list, &bm->empty_list);
+ b->write_lock_pending = 0;
+ b->read_lock_count = 0;
+ b->io_flags = 0;
+ b->validator = NULL;
+
+ if (b->state == BS_ERROR)
+ bm->available_count++;
+ break;
+
+ case BS_CLEAN:
+ /* DOT: reading -> clean */
+ /* DOT: writing -> clean */
+ /* DOT: read_locked -> clean */
+ BUG_ON(!((b->state == BS_READING) ||
+ (b->state == BS_WRITING) ||
+ (b->state == BS_READ_LOCKED)));
+ switch (b->state) {
+ case BS_READING:
+ BUG_ON(bm->reading_count == 0);
+ bm->reading_count--;
+ break;
+
+ case BS_WRITING:
+ BUG_ON(bm->writing_count == 0);
+ bm->writing_count--;
+ b->io_flags = 0;
+ break;
+
+ default:
+ break;
+ }
+ list_add_tail(&b->list, &bm->clean_list);
+ bm->available_count++;
+ break;
+
+ case BS_READING:
+ /* DOT: empty -> reading */
+ BUG_ON(!(b->state == BS_EMPTY));
+ /* FIXME: insert into the hash */
+ __insert_block(bm, b);
+ list_del(&b->list);
+ bm->available_count--;
+ bm->reading_count++;
+ break;
+
+ case BS_WRITING:
+ /* DOT: dirty -> writing */
+ BUG_ON(!(b->state == BS_DIRTY));
+ list_del(&b->list);
+ bm->writing_count++;
+ break;
+
+ case BS_READ_LOCKED:
+ /* DOT: clean -> read_locked */
+ BUG_ON(!(b->state == BS_CLEAN));
+ list_del(&b->list);
+ bm->available_count--;
+ break;
+
+ case BS_READ_LOCKED_DIRTY:
+ /* DOT: dirty -> read_locked_dirty */
+ BUG_ON(!((b->state == BS_DIRTY)));
+ list_del(&b->list);
+ break;
+
+ case BS_WRITE_LOCKED:
+ /* DOT: dirty -> write_locked */
+ /* DOT: clean -> write_locked */
+ BUG_ON(!((b->state == BS_DIRTY) ||
+ (b->state == BS_CLEAN)));
+ list_del(&b->list);
+
+ if (b->state == BS_CLEAN)
+ bm->available_count--;
+ break;
+
+ case BS_DIRTY:
+ /* DOT: write_locked -> dirty */
+ /* DOT: read_locked_dirty -> dirty */
+ BUG_ON(!((b->state == BS_WRITE_LOCKED) ||
+ (b->state == BS_READ_LOCKED_DIRTY)));
+ list_add_tail(&b->list, &bm->dirty_list);
+ break;
+
+ case BS_ERROR:
+ /* DOT: writing -> error */
+ /* DOT: reading -> error */
+ BUG_ON(!((b->state == BS_WRITING) ||
+ (b->state == BS_READING)));
+ list_add_tail(&b->list, &bm->error_list);
+ break;
+ }
+
+ b->state = new_state;
+ /* DOT: } */
+}
+
+/*----------------------------------------------------------------
+ * low level io
+ *--------------------------------------------------------------*/
+typedef void (completion_fn)(unsigned long error, struct dm_block *b);
+
+static void submit_io(struct dm_block *b, int rw,
+ completion_fn fn)
+{
+ struct dm_block_manager *bm = b->bm;
+ struct dm_io_request req;
+ struct dm_io_region region;
+ unsigned sectors_per_block = bm->block_size >> SECTOR_SHIFT;
+
+ region.bdev = bm->bdev;
+ region.sector = b->where * sectors_per_block;
+ region.count = sectors_per_block;
+
+ req.bi_rw = rw;
+ req.mem.type = DM_IO_KMEM;
+ req.mem.offset = 0;
+ req.mem.ptr.addr = b->data;
+ req.notify.fn = (void (*)(unsigned long, void *)) fn;
+ req.notify.context = b;
+ req.client = bm->io;
+
+ if (dm_io(&req, 1, ®ion, NULL) < 0)
+ fn(1, b);
+}
+
+/*----------------------------------------------------------------
+ * High level io
+ *--------------------------------------------------------------*/
+static void __complete_io(unsigned long error, struct dm_block *b)
+{
+ struct dm_block_manager *bm = b->bm;
+
+ if (error) {
+ DMERR("io error = %lu, block = %llu",
+ error , (unsigned long long)b->where);
+ __transition(b, BS_ERROR);
+ } else
+ __transition(b, BS_CLEAN);
+
+ wake_up(&b->io_q);
+ wake_up(&bm->io_q);
+}
+
+static void complete_io(unsigned long error, struct dm_block *b)
+{
+ struct dm_block_manager *bm = b->bm;
+ unsigned long flags;
+
+ spin_lock_irqsave(&bm->lock, flags);
+ __complete_io(error, b);
+ spin_unlock_irqrestore(&bm->lock, flags);
+}
+
+static void read_block(struct dm_block *b)
+{
+ submit_io(b, READ, complete_io);
+}
+
+static void write_block(struct dm_block *b)
+{
+ if (b->validator)
+ b->validator->prepare_for_write(b->validator, b,
+ b->bm->block_size);
+
+ submit_io(b, WRITE | b->io_flags, complete_io);
+}
+
+static void write_dirty(struct dm_block_manager *bm, unsigned count)
+{
+ struct dm_block *b, *tmp;
+ struct list_head dirty;
+ unsigned long flags;
+
+ /* Grab the first |count| entries from the dirty list */
+ INIT_LIST_HEAD(&dirty);
+ spin_lock_irqsave(&bm->lock, flags);
+ list_for_each_entry_safe(b, tmp, &bm->dirty_list, list) {
+ if (count-- == 0)
+ break;
+ __transition(b, BS_WRITING);
+ list_add_tail(&b->list, &dirty);
+ }
+ spin_unlock_irqrestore(&bm->lock, flags);
+
+ list_for_each_entry_safe(b, tmp, &dirty, list) {
+ list_del(&b->list);
+ write_block(b);
+ }
+}
+
+static void write_all_dirty(struct dm_block_manager *bm)
+{
+ write_dirty(bm, bm->cache_size);
+}
+
+static void __clear_errors(struct dm_block_manager *bm)
+{
+ struct dm_block *b, *tmp;
+ list_for_each_entry_safe(b, tmp, &bm->error_list, list)
+ __transition(b, BS_EMPTY);
+}
+
+/*----------------------------------------------------------------
+ * Waiting
+ *--------------------------------------------------------------*/
+#ifdef __CHECKER__
+# define __retains(x) __attribute__((context(x, 1, 1)))
+#else
+# define __retains(x)
+#endif
+
+#define __wait_block(wq, lock, flags, sched_fn, condition) \
+do { \
+ int ret = 0; \
+ \
+ DEFINE_WAIT(wait); \
+ add_wait_queue(wq, &wait); \
+ \
+ for (;;) { \
+ prepare_to_wait(wq, &wait, TASK_INTERRUPTIBLE); \
+ if (condition) \
+ break; \
+ \
+ spin_unlock_irqrestore(lock, flags); \
+ if (signal_pending(current)) { \
+ ret = -ERESTARTSYS; \
+ spin_lock_irqsave(lock, flags); \
+ break; \
+ } \
+ \
+ sched_fn(); \
+ spin_lock_irqsave(lock, flags); \
+ } \
+ \
+ finish_wait(wq, &wait); \
+ return ret; \
+} while (0)
+
+static int __wait_io(struct dm_block *b, unsigned long *flags)
+ __retains(&b->bm->lock)
+{
+ __wait_block(&b->io_q, &b->bm->lock, *flags, io_schedule,
+ ((b->state != BS_READING) && (b->state != BS_WRITING)));
+}
+
+static int __wait_unlocked(struct dm_block *b, unsigned long *flags)
+ __retains(&b->bm->lock)
+{
+ __wait_block(&b->io_q, &b->bm->lock, *flags, schedule,
+ ((b->state == BS_CLEAN) || (b->state == BS_DIRTY)));
+}
+
+static int __wait_read_lockable(struct dm_block *b, unsigned long *flags)
+ __retains(&b->bm->lock)
+{
+ __wait_block(&b->io_q, &b->bm->lock, *flags, schedule,
+ (!b->write_lock_pending && (b->state == BS_CLEAN ||
+ b->state == BS_DIRTY ||
+ b->state == BS_READ_LOCKED)));
+}
+
+static int __wait_all_writes(struct dm_block_manager *bm, unsigned long *flags)
+ __retains(&bm->lock)
+{
+ __wait_block(&bm->io_q, &bm->lock, *flags, io_schedule,
+ !bm->writing_count);
+}
+
+static int __wait_all_io(struct dm_block_manager *bm, unsigned long *flags)
+ __retains(&bm->lock)
+{
+ __wait_block(&bm->io_q, &bm->lock, *flags, io_schedule,
+ !bm->writing_count && !bm->reading_count);
+}
+
+static int __wait_clean(struct dm_block_manager *bm, unsigned long *flags)
+ __retains(&bm->lock)
+{
+ __wait_block(&bm->io_q, &bm->lock, *flags, io_schedule,
+ (!list_empty(&bm->clean_list) ||
+ (bm->writing_count == 0)));
+}
+
+/*----------------------------------------------------------------
+ * Finding a free block to recycle
+ *--------------------------------------------------------------*/
+static int recycle_block(struct dm_block_manager *bm, dm_block_t where,
+ int need_read, struct dm_block_validator *v,
+ struct dm_block **result)
+{
+ int ret = 0;
+ struct dm_block *b;
+ unsigned long flags, available;
+
+ /* wait for a block to appear on the empty or clean lists */
+ spin_lock_irqsave(&bm->lock, flags);
+ while (1) {
+ /*
+ * Once we can lock and do io concurrently then we should
+ * probably flush at bm->cache_size / 2 and write _all_
+ * dirty blocks.
+ */
+ available = bm->available_count + bm->writing_count;
+ if (available < bm->cache_size / 4) {
+ spin_unlock_irqrestore(&bm->lock, flags);
+ write_dirty(bm, bm->cache_size / 4);
+ spin_lock_irqsave(&bm->lock, flags);
+ }
+
+ if (!list_empty(&bm->empty_list)) {
+ b = list_first_entry(&bm->empty_list, struct dm_block, list);
+ break;
+
+ } else if (!list_empty(&bm->clean_list)) {
+ b = list_first_entry(&bm->clean_list, struct dm_block, list);
+ __transition(b, BS_EMPTY);
+ break;
+ }
+
+ __wait_clean(bm, &flags);
+ }
+
+ b->where = where;
+ b->validator = v;
+ __transition(b, BS_READING);
+
+ if (!need_read) {
+ memset(b->data, 0, bm->block_size);
+ __transition(b, BS_CLEAN);
+ } else {
+ spin_unlock_irqrestore(&bm->lock, flags);
+ read_block(b);
+ spin_lock_irqsave(&bm->lock, flags);
+ __wait_io(b, &flags);
+
+ /* FIXME: can |b| have been recycled between io completion and here ? */
+
+ /* did the io succeed ? */
+ if (b->state == BS_ERROR) {
+ /* Since this is a read that has failed we can
+ * clear the error immediately. Failed writes are
+ * revealed during a commit.
+ */
+ __transition(b, BS_EMPTY);
+ ret = -EIO;
+ }
+
+ if (b->validator) {
+ ret = b->validator->check(b->validator, b, bm->block_size);
+ if (ret) {
+ DMERR("%s validator check failed for block %llu",
+ b->validator->name, (unsigned long long)b->where);
+ __transition(b, BS_EMPTY);
+ }
+ }
+ }
+ spin_unlock_irqrestore(&bm->lock, flags);
+
+ if (ret == 0)
+ *result = b;
+ return ret;
+}
+
+/*----------------------------------------------------------------
+ * Low level block management
+ *--------------------------------------------------------------*/
+
+/* Alloc a page if block_size equals PAGE_SIZE or kmalloc it. */
+static void *_alloc_block(struct dm_block_manager *bm)
+{
+ void *r;
+
+ if (bm->block_size == PAGE_SIZE) {
+ struct page *p = alloc_page(GFP_KERNEL);
+ r = p ? page_address(p) : NULL;
+
+ } else
+ r = kmalloc(bm->block_size + SECTOR_SIZE, GFP_KERNEL);
+
+ return r;
+}
+
+static struct dm_block *alloc_block(struct dm_block_manager *bm)
+{
+ struct dm_block *b = kmalloc(sizeof(*b), GFP_KERNEL);
+ if (!b)
+ return NULL;
+
+ INIT_LIST_HEAD(&b->list);
+ INIT_HLIST_NODE(&b->hlist);
+
+ b->data_actual = _alloc_block(bm);
+ if (!b->data_actual) {
+ kfree(b);
+ return NULL;
+ }
+
+ b->validator = NULL;
+ b->data = (void *)ALIGN((uintptr_t)b->data_actual, SECTOR_SIZE);
+ b->state = BS_EMPTY;
+ init_waitqueue_head(&b->io_q);
+ b->read_lock_count = 0;
+ b->write_lock_pending = 0;
+ b->io_flags = 0;
+ b->bm = bm;
+
+ return b;
+}
+
+static void free_block(struct dm_block *b)
+{
+ if (b->bm->block_size == PAGE_SIZE)
+ free_page((unsigned long) b->data_actual);
+ else
+ kfree(b->data_actual);
+
+ kfree(b);
+}
+
+static int populate_bm(struct dm_block_manager *bm, unsigned count)
+{
+ int i;
+ LIST_HEAD(bs);
+
+ for (i = 0; i < count; i++) {
+ struct dm_block *b = alloc_block(bm);
+ if (!b) {
+ struct dm_block *tmp;
+ list_for_each_entry_safe(b, tmp, &bs, list)
+ free_block(b);
+ return -ENOMEM;
+ }
+
+ list_add(&b->list, &bs);
+ }
+
+ list_replace(&bs, &bm->empty_list);
+ bm->available_count = count;
+
+ return 0;
+}
+
+/*----------------------------------------------------------------
+ * Public interface
+ *--------------------------------------------------------------*/
+static unsigned calc_hash_size(unsigned cache_size)
+{
+ unsigned r = 32; /* minimum size is 16 */
+
+ while (r < cache_size)
+ r <<= 1;
+
+ return r >> 1;
+}
+
+struct dm_block_manager *
+dm_block_manager_create(struct block_device *bdev,
+ unsigned block_size, unsigned cache_size)
+{
+ unsigned i;
+ unsigned hash_size = calc_hash_size(cache_size);
+ size_t len = sizeof(struct dm_block_manager) +
+ sizeof(struct hlist_head) * hash_size;
+ struct dm_block_manager *bm;
+
+ bm = kmalloc(len, GFP_KERNEL);
+ if (!bm)
+ return NULL;
+ bm->bdev = bdev;
+ bm->cache_size = max(16u, cache_size);
+ bm->block_size = block_size;
+ bm->nr_blocks = i_size_read(bdev->bd_inode);
+ do_div(bm->nr_blocks, block_size);
+ init_waitqueue_head(&bm->io_q);
+ spin_lock_init(&bm->lock);
+
+ INIT_LIST_HEAD(&bm->empty_list);
+ INIT_LIST_HEAD(&bm->clean_list);
+ INIT_LIST_HEAD(&bm->dirty_list);
+ INIT_LIST_HEAD(&bm->error_list);
+ bm->available_count = 0;
+ bm->reading_count = 0;
+ bm->writing_count = 0;
+
+ bm->hash_size = hash_size;
+ bm->hash_mask = hash_size - 1;
+ for (i = 0; i < hash_size; i++)
+ INIT_HLIST_HEAD(bm->buckets + i);
+
+ bm->io = dm_io_client_create();
+ if (!bm->io) {
+ kfree(bm);
+ return NULL;
+ }
+
+ if (populate_bm(bm, cache_size) < 0) {
+ dm_io_client_destroy(bm->io);
+ kfree(bm);
+ return NULL;
+ }
+
+ return bm;
+}
+EXPORT_SYMBOL_GPL(dm_block_manager_create);
+
+void dm_block_manager_destroy(struct dm_block_manager *bm)
+{
+ int i;
+ struct dm_block *b, *btmp;
+ struct hlist_node *n, *tmp;
+
+ dm_io_client_destroy(bm->io);
+
+ for (i = 0; i < bm->hash_size; i++)
+ hlist_for_each_entry_safe(b, n, tmp, bm->buckets + i, hlist)
+ free_block(b);
+
+ list_for_each_entry_safe(b, btmp, &bm->empty_list, list)
+ free_block(b);
+
+ kfree(bm);
+}
+EXPORT_SYMBOL_GPL(dm_block_manager_destroy);
+
+unsigned dm_bm_block_size(struct dm_block_manager *bm)
+{
+ return bm->block_size;
+}
+EXPORT_SYMBOL_GPL(dm_bm_block_size);
+
+dm_block_t dm_bm_nr_blocks(struct dm_block_manager *bm)
+{
+ return bm->nr_blocks;
+}
+
+static int lock_internal(struct dm_block_manager *bm, dm_block_t block,
+ int how, int need_read, int can_block,
+ struct dm_block_validator *v,
+ struct dm_block **result)
+{
+ int r = 0;
+ struct dm_block *b;
+ unsigned long flags;
+
+ spin_lock_irqsave(&bm->lock, flags);
+retry:
+ b = __find_block(bm, block);
+ if (b) {
+ if (need_read) {
+ if (b->validator && (v != b->validator)) {
+ DMERR("validator mismatch (old=%s vs new=%s) for block %llu",
+ b->validator->name, v->name,
+ (unsigned long long)b->where);
+ spin_unlock_irqrestore(&bm->lock, flags);
+ return -EINVAL;
+
+ } else if (!b->validator && v) {
+ b->validator = v;
+ r = b->validator->check(b->validator, b, bm->block_size);
+ if (r) {
+ DMERR("%s validator check failed for block %llu",
+ b->validator->name,
+ (unsigned long long)b->where);
+ spin_unlock_irqrestore(&bm->lock, flags);
+ return r;
+ }
+ }
+ } else
+ b->validator = v;
+
+ switch (how) {
+ case READ:
+ if (b->write_lock_pending || (b->state != BS_CLEAN &&
+ b->state != BS_DIRTY &&
+ b->state != BS_READ_LOCKED)) {
+ if (!can_block) {
+ spin_unlock_irqrestore(&bm->lock, flags);
+ return -EWOULDBLOCK;
+ }
+
+ __wait_read_lockable(b, &flags);
+
+ if (b->where != block)
+ goto retry;
+ }
+ break;
+
+ case WRITE:
+ while (b->state != BS_CLEAN && b->state != BS_DIRTY) {
+ if (!can_block) {
+ spin_unlock_irqrestore(&bm->lock, flags);
+ return -EWOULDBLOCK;
+ }
+
+ b->write_lock_pending++;
+ __wait_unlocked(b, &flags);
+ b->write_lock_pending--;
+ if (b->where != block)
+ goto retry;
+ }
+ break;
+ }
+
+ } else if (!can_block) {
+ r = -EWOULDBLOCK;
+ goto out;
+
+ } else {
+ spin_unlock_irqrestore(&bm->lock, flags);
+ r = recycle_block(bm, block, need_read, v, &b);
+ spin_lock_irqsave(&bm->lock, flags);
+ }
+
+ if (r == 0) {
+ switch (how) {
+ case READ:
+ b->read_lock_count++;
+
+ if (b->state == BS_DIRTY)
+ __transition(b, BS_READ_LOCKED_DIRTY);
+ else if (b->state == BS_CLEAN)
+ __transition(b, BS_READ_LOCKED);
+ break;
+
+ case WRITE:
+ __transition(b, BS_WRITE_LOCKED);
+ break;
+ }
+
+ *result = b;
+ }
+
+out:
+ spin_unlock_irqrestore(&bm->lock, flags);
+ return r;
+}
+
+int dm_bm_read_lock(struct dm_block_manager *bm, dm_block_t b,
+ struct dm_block_validator *v,
+ struct dm_block **result)
+{
+ return lock_internal(bm, b, READ, 1, 1, v, result);
+}
+EXPORT_SYMBOL_GPL(dm_bm_read_lock);
+
+int dm_bm_write_lock(struct dm_block_manager *bm,
+ dm_block_t b, struct dm_block_validator *v,
+ struct dm_block **result)
+{
+ return lock_internal(bm, b, WRITE, 1, 1, v, result);
+}
+EXPORT_SYMBOL_GPL(dm_bm_write_lock);
+
+int dm_bm_read_try_lock(struct dm_block_manager *bm,
+ dm_block_t b, struct dm_block_validator *v,
+ struct dm_block **result)
+{
+ return lock_internal(bm, b, READ, 1, 0, v, result);
+}
+
+int dm_bm_write_lock_zero(struct dm_block_manager *bm,
+ dm_block_t b, struct dm_block_validator *v,
+ struct dm_block **result)
+{
+ int r = lock_internal(bm, b, WRITE, 0, 1, v, result);
+ if (!r)
+ memset((*result)->data, 0, bm->block_size);
+ return r;
+}
+
+int dm_bm_unlock(struct dm_block *b)
+{
+ int ret = 0;
+ unsigned long flags;
+
+ spin_lock_irqsave(&b->bm->lock, flags);
+ switch (b->state) {
+ case BS_WRITE_LOCKED:
+ __transition(b, BS_DIRTY);
+ wake_up(&b->io_q);
+ break;
+
+ case BS_READ_LOCKED:
+ if (!--b->read_lock_count) {
+ __transition(b, BS_CLEAN);
+ wake_up(&b->io_q);
+ }
+ break;
+
+ case BS_READ_LOCKED_DIRTY:
+ if (!--b->read_lock_count) {
+ __transition(b, BS_DIRTY);
+ wake_up(&b->io_q);
+ }
+ break;
+
+ default:
+ DMERR("block = %llu not locked",
+ (unsigned long long)b->where);
+ ret = -EINVAL;
+ break;
+ }
+ spin_unlock_irqrestore(&b->bm->lock, flags);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(dm_bm_unlock);
+
+static int __wait_flush(struct dm_block_manager *bm)
+{
+ int ret = 0;
+ unsigned long flags;
+
+ spin_lock_irqsave(&bm->lock, flags);
+ __wait_all_writes(bm, &flags);
+
+ if (!list_empty(&bm->error_list)) {
+ ret = -EIO;
+ __clear_errors(bm);
+ }
+ spin_unlock_irqrestore(&bm->lock, flags);
+
+ return ret;
+}
+
+int dm_bm_flush_and_unlock(struct dm_block_manager *bm,
+ struct dm_block *superblock)
+{
+ int r;
+ unsigned long flags;
+
+ write_all_dirty(bm);
+ r = __wait_flush(bm);
+ if (r)
+ return r;
+
+ spin_lock_irqsave(&bm->lock, flags);
+ superblock->io_flags = REQ_FUA | REQ_FLUSH;
+ spin_unlock_irqrestore(&bm->lock, flags);
+
+ dm_bm_unlock(superblock);
+ write_all_dirty(bm);
+
+ return __wait_flush(bm);
+}
+
+int dm_bm_rebind_block_device(struct dm_block_manager *bm,
+ struct block_device *bdev)
+{
+ unsigned long flags;
+ dm_block_t nr_blocks = i_size_read(bdev->bd_inode);
+ do_div(nr_blocks, bm->block_size);
+
+ spin_lock_irqsave(&bm->lock, flags);
+ if (nr_blocks < bm->nr_blocks) {
+ spin_unlock_irqrestore(&bm->lock, flags);
+ return -EINVAL;
+ }
+
+ bm->bdev = bdev;
+ bm->nr_blocks = nr_blocks;
+
+ /* wait for any in-flight io that may be using the old bdev */
+ __wait_all_io(bm, &flags);
+ spin_unlock_irqrestore(&bm->lock, flags);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(dm_bm_rebind_block_device);
+
+/*----------------------------------------------------------------*/
--- /dev/null
+/*
+ * Copyright (C) 2011 Red Hat, Inc. All rights reserved.
+ *
+ * This file is released under the GPL.
+ */
+
+#ifndef _LINUX_DM_BLOCK_MANAGER_H
+#define _LINUX_DM_BLOCK_MANAGER_H
+
+#include <linux/blkdev.h>
+#include <linux/types.h>
+#include <linux/crc32c.h>
+
+/*----------------------------------------------------------------*/
+
+/*
+ * Number of blocks.
+ */
+typedef uint64_t dm_block_t;
+
+/*
+ * An opaque handle to a block of data.
+ */
+struct dm_block;
+
+dm_block_t dm_block_location(struct dm_block *b);
+void *dm_block_data(struct dm_block *b);
+
+/*
+ * Use CRC32 checksumming on data blocks.
+ */
+static inline __le32 dm_block_csum_data(const void *data, unsigned length)
+{
+ return __cpu_to_le32(crc32c(~(u32)0, data, length));
+}
+
+/*----------------------------------------------------------------*/
+
+struct dm_block_manager;
+struct dm_block_manager *dm_block_manager_create(struct block_device *bdev, unsigned block_size, unsigned cache_size);
+void dm_block_manager_destroy(struct dm_block_manager *bm);
+
+unsigned dm_bm_block_size(struct dm_block_manager *bm);
+dm_block_t dm_bm_nr_blocks(struct dm_block_manager *bm);
+
+/*----------------------------------------------------------------*/
+
+/*
+ * The validator allows the caller to verify newly-read data and modify
+ * the data just before writing, e.g. to calculate checksums. It's
+ * important to be consistent with your use of validators. The only time
+ * you can change validators is if you call dm_bm_write_lock_zero.
+ */
+struct dm_block_validator {
+ const char *name;
+ void (*prepare_for_write)(struct dm_block_validator *v, struct dm_block *b, size_t block_size);
+
+ /*
+ * Return 0 if the checksum is valid or < 0 on error.
+ */
+ int (*check)(struct dm_block_validator *v, struct dm_block *b, size_t block_size);
+};
+
+/*----------------------------------------------------------------*/
+
+/*
+ * You can have multiple concurrent readers or a single writer holding a
+ * block lock.
+ */
+
+/*
+ * dm_bm_lock() locks a block and returns through @result a pointer to
+ * memory that holds a copy of that block. If you have write-locked the
+ * block then any changes you make to memory pointed to by @result will be
+ * written back to the disk sometime after dm_bm_unlock is called.
+ */
+int dm_bm_read_lock(struct dm_block_manager *bm, dm_block_t b,
+ struct dm_block_validator *v,
+ struct dm_block **result);
+
+int dm_bm_write_lock(struct dm_block_manager *bm, dm_block_t b,
+ struct dm_block_validator *v,
+ struct dm_block **result);
+
+/*
+ * The *_try_lock variants return -EWOULDBLOCK if the block isn't
+ * available immediately.
+ */
+int dm_bm_read_try_lock(struct dm_block_manager *bm, dm_block_t b,
+ struct dm_block_validator *v,
+ struct dm_block **result);
+
+/*
+ * Use dm_bm_write_lock_zero() when you know you're going to
+ * overwrite the block completely. It saves a disk read.
+ */
+int dm_bm_write_lock_zero(struct dm_block_manager *bm, dm_block_t b,
+ struct dm_block_validator *v,
+ struct dm_block **result);
+
+int dm_bm_unlock(struct dm_block *b);
+
+/*
+ * It's a common idiom to have a superblock that should be committed last.
+ *
+ * @superblock should be write-locked on entry. It will be unlocked during
+ * this function. All dirty blocks are guaranteed to be written and flushed
+ * before the superblock.
+ *
+ * This method always blocks.
+ */
+int dm_bm_flush_and_unlock(struct dm_block_manager *bm,
+ struct dm_block *superblock);
+
+/*
+ * The client may wish to change the block device to which the block
+ * manager points. If you use this function then the cache remains intact,
+ * so the data must be identical on the both devices, e.g. a different
+ * path to the same disk, and it must be at least as big.
+ *
+ * This function guarantees that once it returns, no further IO will occur
+ * on the old device.
+ */
+int dm_bm_rebind_block_device(struct dm_block_manager *bm,
+ struct block_device *bdev);
+
+/*----------------------------------------------------------------*/
+
+#endif /* _LINUX_DM_BLOCK_MANAGER_H */
--- /dev/null
+/*
+ * Copyright (C) 2011 Red Hat, Inc. All rights reserved.
+ *
+ * This file is released under the GPL.
+ */
+
+#ifndef DM_BTREE_INTERNAL_H
+#define DM_BTREE_INTERNAL_H
+
+#include "dm-btree.h"
+
+/*----------------------------------------------------------------*/
+
+/*
+ * We'll need 2 accessor functions for n->csum and n->blocknr
+ * to support dm-btree-spine.c in that case.
+ */
+
+enum node_flags {
+ INTERNAL_NODE = 1,
+ LEAF_NODE = 1 << 1
+};
+
+/*
+ * To ease coding I'm packing all the different node types into one
+ * structure. We can optimise later.
+ */
+struct node_header {
+ __le32 csum;
+ __le32 flags;
+ __le64 blocknr; /* Block this node is supposed to live in. */
+
+ __le32 nr_entries;
+ __le32 max_entries;
+} __packed;
+
+struct node {
+ struct node_header header;
+ __le64 keys[0];
+} __packed;
+
+
+void inc_children(struct dm_transaction_manager *tm, struct node *n,
+ struct dm_btree_value_type *vt);
+
+int new_block(struct dm_btree_info *info, struct dm_block **result);
+int unlock_for_block(struct dm_btree_info *info, struct dm_block *b);
+
+/*
+ * Spines keep track of the rolling locks. There are 2 variants, read-only
+ * and one that uses shadowing. These are separate structs to allow the
+ * type checker to spot misuse, for example accidentally calling read_lock
+ * on a shadow spine.
+ */
+struct ro_spine {
+ struct dm_btree_info *info;
+
+ int count;
+ struct dm_block *nodes[2];
+};
+
+void init_ro_spine(struct ro_spine *s, struct dm_btree_info *info);
+int exit_ro_spine(struct ro_spine *s);
+int ro_step(struct ro_spine *s, dm_block_t new_child);
+struct node *ro_node(struct ro_spine *s);
+
+struct shadow_spine {
+ struct dm_btree_info *info;
+
+ int count;
+ struct dm_block *nodes[2];
+
+ dm_block_t root;
+};
+
+void init_shadow_spine(struct shadow_spine *s, struct dm_btree_info *info);
+int exit_shadow_spine(struct shadow_spine *s);
+
+int shadow_step(struct shadow_spine *s, dm_block_t b,
+ struct dm_btree_value_type *vt, int *inc);
+
+struct dm_block *shadow_current(struct shadow_spine *s);
+
+struct dm_block *shadow_parent(struct shadow_spine *s);
+
+int shadow_root(struct shadow_spine *s);
+
+/*
+ * Some inlines.
+ */
+static inline __le64 *key_ptr(struct node *n, uint32_t index)
+{
+ return n->keys + index;
+}
+
+static inline void *value_base(struct node *n)
+{
+ return &n->keys[__le32_to_cpu(n->header.max_entries)];
+}
+
+static inline void *value_ptr(struct node *n, uint32_t index, size_t value_size)
+{
+ return value_base(n) + (value_size * index);
+}
+
+/*
+ * Assumes the values are suitably-aligned and converts to core format.
+ */
+static inline uint64_t value64(struct node *n, uint32_t index)
+{
+ __le64 *values = value_base(n);
+ return __le64_to_cpu(values[index]);
+}
+
+/*
+ * Searching for a key within a single node.
+ */
+int lower_bound(struct node *n, uint64_t key);
+
+extern struct dm_block_validator btree_node_validator;
+
+/*----------------------------------------------------------------*/
+
+#endif /* DM_BTREE_INTERNAL_H */
--- /dev/null
+/*
+ * Copyright (C) 2011 Red Hat, Inc. All rights reserved.
+ *
+ * This file is released under the GPL.
+ */
+
+#include "dm-btree.h"
+#include "dm-btree-internal.h"
+#include "dm-transaction-manager.h"
+
+/*
+ * Removing an entry from a btree
+ * ==============================
+ *
+ * A very important constraint for our btree is that no node, except the
+ * root, may have fewer than a certain number of entries.
+ * (MIN_ENTRIES <= nr_entries <= MAX_ENTRIES).
+ *
+ * Ensuring this is complicated by the way we want to only ever hold the
+ * locks on 2 nodes concurrently, and only change nodes in a top to bottom
+ * fashion.
+ *
+ * Each node may have a left or right sibling. When decending the spine,
+ * if a node contains only MIN_ENTRIES then we try and increase this to at
+ * least MIN_ENTRIES + 1. We do this in the following ways:
+ *
+ * [A] No siblings => this can only happen if the node is the root, in which
+ * case we copy the childs contents over the root.
+ *
+ * [B] No left sibling
+ * ==> rebalance(node, right sibling)
+ *
+ * [C] No right sibling
+ * ==> rebalance(left sibling, node)
+ *
+ * [D] Both siblings, total_entries(left, node, right) <= DEL_THRESHOLD
+ * ==> delete node adding it's contents to left and right
+ *
+ * [E] Both siblings, total_entries(left, node, right) > DEL_THRESHOLD
+ * ==> rebalance(left, node, right)
+ *
+ * After these operations it's possible that the our original node no
+ * longer contains the desired sub tree. For this reason this rebalancing
+ * is performed on the children of the current node. This also avoids
+ * having a special case for the root.
+ *
+ * Once this rebalancing has occurred we can then step into the child node
+ * for internal nodes. Or delete the entry for leaf nodes.
+ */
+
+/*
+ * Some little utilities for moving node data around.
+ */
+static void node_shift(struct node *n, int shift)
+{
+ uint32_t nr_entries = __le32_to_cpu(n->header.nr_entries);
+
+ if (shift < 0) {
+ shift = -shift;
+ memmove(key_ptr(n, 0),
+ key_ptr(n, shift),
+ (nr_entries - shift) * sizeof(__le64));
+ memmove(value_ptr(n, 0, sizeof(__le64)),
+ value_ptr(n, shift, sizeof(__le64)),
+ (nr_entries - shift) * sizeof(__le64));
+ } else {
+ memmove(key_ptr(n, shift),
+ key_ptr(n, 0),
+ nr_entries * sizeof(__le64));
+ memmove(value_ptr(n, shift, sizeof(__le64)),
+ value_ptr(n, 0, sizeof(__le64)),
+ nr_entries * sizeof(__le64));
+ }
+}
+
+static void node_copy(struct node *left, struct node *right, int shift)
+{
+ uint32_t nr_left = __le32_to_cpu(left->header.nr_entries);
+
+ if (shift < 0) {
+ shift = -shift;
+ memcpy(key_ptr(left, nr_left),
+ key_ptr(right, 0),
+ shift * sizeof(__le64));
+ memcpy(value_ptr(left, nr_left, sizeof(__le64)),
+ value_ptr(right, 0, sizeof(__le64)),
+ shift * sizeof(__le64));
+ } else {
+ memcpy(key_ptr(right, 0),
+ key_ptr(left, nr_left - shift),
+ shift * sizeof(__le64));
+ memcpy(value_ptr(right, 0, sizeof(__le64)),
+ value_ptr(left, nr_left - shift, sizeof(__le64)),
+ shift * sizeof(__le64));
+ }
+}
+
+/*
+ * Delete a specific entry from a leaf node.
+ */
+static void delete_at(struct node *n, unsigned index, size_t value_size)
+{
+ unsigned nr_entries = __le32_to_cpu(n->header.nr_entries);
+ unsigned nr_to_copy = nr_entries - (index + 1);
+
+ if (nr_to_copy) {
+ memmove(key_ptr(n, index),
+ key_ptr(n, index + 1),
+ nr_to_copy * sizeof(__le64));
+
+ memmove(value_ptr(n, index, value_size),
+ value_ptr(n, index + 1, value_size),
+ nr_to_copy * value_size);
+ }
+
+ n->header.nr_entries = __cpu_to_le32(nr_entries - 1);
+}
+
+static unsigned del_threshold(struct node *n)
+{
+ return __le32_to_cpu(n->header.max_entries) / 3;
+}
+
+static unsigned merge_threshold(struct node *n)
+{
+ /*
+ * The extra one is because we know we're potentially going to
+ * delete an entry.
+ */
+ return 2 * (__le32_to_cpu(n->header.max_entries) / 3) + 1;
+}
+
+struct child {
+ unsigned index;
+ struct dm_block *block;
+ struct node *n;
+};
+
+static struct dm_btree_value_type le64_type_ = {
+ .context = NULL,
+ .size = sizeof(__le64),
+ .inc = NULL,
+ .dec = NULL,
+ .equal = NULL
+};
+
+static int init_child(struct dm_btree_info *info, struct node *parent,
+ unsigned index, struct child *result)
+{
+ int r, inc;
+ dm_block_t root;
+
+ result->index = index;
+ root = value64(parent, index);
+
+ r = dm_tm_shadow_block(info->tm, root, &btree_node_validator,
+ &result->block, &inc);
+ if (r)
+ return r;
+
+ result->n = dm_block_data(result->block);
+ if (inc)
+ inc_children(info->tm, result->n, &le64_type_);
+ return 0;
+}
+
+static int exit_child(struct dm_btree_info *info, struct child *c)
+{
+ return dm_tm_unlock(info->tm, c->block);
+}
+
+static void shift(struct node *left, struct node *right, int count)
+{
+ if (count == 0)
+ return;
+
+ if (count > 0) {
+ node_shift(right, count);
+ node_copy(left, right, count);
+
+ } else {
+ node_copy(left, right, count);
+ node_shift(right, count);
+ }
+
+ left->header.nr_entries =
+ __cpu_to_le32(__le32_to_cpu(left->header.nr_entries) - count);
+ right->header.nr_entries =
+ __cpu_to_le32(__le32_to_cpu(right->header.nr_entries) + count);
+}
+
+static void __rebalance2(struct dm_btree_info *info, struct node *parent,
+ struct child *l, struct child *r)
+{
+ struct node *left = l->n;
+ struct node *right = r->n;
+ uint32_t nr_left = __le32_to_cpu(left->header.nr_entries);
+ uint32_t nr_right = __le32_to_cpu(right->header.nr_entries);
+
+ if (nr_left + nr_right <= merge_threshold(left)) {
+ /* merge */
+ node_copy(left, right, -nr_right);
+ left->header.nr_entries = __cpu_to_le32(nr_left + nr_right);
+
+ *((__le64 *) value_ptr(parent, l->index, sizeof(__le64))) =
+ __cpu_to_le64(dm_block_location(l->block));
+ delete_at(parent, r->index, sizeof(__le64));
+
+ /*
+ * We need to decrement the right block, but not it's
+ * children, since they're still referenced by @left
+ */
+ dm_tm_dec(info->tm, dm_block_location(r->block));
+
+ } else {
+ /* rebalance */
+ unsigned target_left = (nr_left + nr_right) / 2;
+ shift(left, right, nr_left - target_left);
+ *((__le64 *) value_ptr(parent, l->index, sizeof(__le64))) =
+ __cpu_to_le64(dm_block_location(l->block));
+ *((__le64 *) value_ptr(parent, r->index, sizeof(__le64))) =
+ __cpu_to_le64(dm_block_location(r->block));
+ *key_ptr(parent, r->index) = right->keys[0];
+ }
+}
+
+static int rebalance2(struct shadow_spine *s, struct dm_btree_info *info,
+ unsigned left_index)
+{
+ int r;
+ struct node *parent;
+ struct child left, right;
+
+ parent = dm_block_data(shadow_current(s));
+
+ r = init_child(info, parent, left_index, &left);
+ if (r)
+ return r;
+
+ r = init_child(info, parent, left_index + 1, &right);
+ if (r) {
+ exit_child(info, &left);
+ return r;
+ }
+
+ __rebalance2(info, parent, &left, &right);
+
+ r = exit_child(info, &left);
+ if (r) {
+ exit_child(info, &right);
+ return r;
+ }
+
+ r = exit_child(info, &right);
+ if (r)
+ return r;
+
+ return 0;
+}
+
+static void __rebalance3(struct dm_btree_info *info, struct node *parent,
+ struct child *l, struct child *c, struct child *r)
+{
+ struct node *left = l->n;
+ struct node *center = c->n;
+ struct node *right = r->n;
+
+ uint32_t nr_left = __le32_to_cpu(left->header.nr_entries);
+ uint32_t nr_center = __le32_to_cpu(center->header.nr_entries);
+ uint32_t nr_right = __le32_to_cpu(right->header.nr_entries);
+ uint32_t max_entries = __le32_to_cpu(left->header.max_entries);
+
+ if (((nr_left + nr_center + nr_right) / 2) < merge_threshold(center)) {
+ /* delete center node:
+ *
+ * We dump as many entries from center as possible into
+ * left, then the rest in right, then rebalance2. This
+ * wastes some cpu, but I want something simple atm.
+ */
+
+ unsigned shift = min(max_entries - nr_left, nr_center);
+ node_copy(left, center, -shift);
+ left->header.nr_entries = __cpu_to_le32(nr_left + shift);
+
+ if (shift != nr_center) {
+ shift = nr_center - shift;
+ node_shift(right, shift);
+ node_copy(center, right, shift);
+ right->header.nr_entries = __cpu_to_le32(nr_right + shift);
+ }
+
+ *((__le64 *) value_ptr(parent, l->index, sizeof(__le64))) =
+ __cpu_to_le64(dm_block_location(l->block));
+ *((__le64 *) value_ptr(parent, r->index, sizeof(__le64))) =
+ __cpu_to_le64(dm_block_location(r->block));
+ *key_ptr(parent, r->index) = right->keys[0];
+
+ delete_at(parent, c->index, sizeof(__le64));
+ r->index--;
+
+ dm_tm_dec(info->tm, dm_block_location(c->block));
+ __rebalance2(info, parent, l, r);
+
+ } else {
+ /* rebalance */
+ unsigned target = (nr_left + nr_center + nr_right) / 3;
+ BUG_ON(target == nr_center);
+
+ /* adjust the left node */
+ shift(left, center, nr_left - target);
+
+ /* adjust the right node */
+ shift(center, right, target - nr_right);
+
+ *((__le64 *) value_ptr(parent, l->index, sizeof(__le64))) =
+ __cpu_to_le64(dm_block_location(l->block));
+ *((__le64 *) value_ptr(parent, c->index, sizeof(__le64))) =
+ __cpu_to_le64(dm_block_location(c->block));
+ *((__le64 *) value_ptr(parent, r->index, sizeof(__le64))) =
+ __cpu_to_le64(dm_block_location(r->block));
+
+ *key_ptr(parent, c->index) = center->keys[0];
+ *key_ptr(parent, r->index) = right->keys[0];
+ }
+}
+
+static int rebalance3(struct shadow_spine *s, struct dm_btree_info *info,
+ unsigned left_index)
+{
+ int r;
+ struct node *parent = dm_block_data(shadow_current(s));
+ struct child left, center, right;
+
+ /* FIXME: fill out an array? */
+ r = init_child(info, parent, left_index, &left);
+ if (r)
+ return r;
+
+ r = init_child(info, parent, left_index + 1, ¢er);
+ if (r) {
+ exit_child(info, &left);
+ return r;
+ }
+
+ r = init_child(info, parent, left_index + 2, &right);
+ if (r) {
+ exit_child(info, &left);
+ exit_child(info, ¢er);
+ return r;
+ }
+
+ __rebalance3(info, parent, &left, ¢er, &right);
+
+ r = exit_child(info, &left);
+ if (r) {
+ exit_child(info, ¢er);
+ exit_child(info, &right);
+ return r;
+ }
+
+ r = exit_child(info, ¢er);
+ if (r) {
+ exit_child(info, &right);
+ return r;
+ }
+
+ r = exit_child(info, &right);
+ if (r)
+ return r;
+
+ return 0;
+}
+
+static int get_nr_entries(struct dm_transaction_manager *tm,
+ dm_block_t b, uint32_t *result)
+{
+ int r;
+ struct dm_block *block;
+ struct node *c;
+
+ r = dm_tm_read_lock(tm, b, &btree_node_validator, &block);
+ if (r)
+ return r;
+
+ c = dm_block_data(block);
+ *result = __le32_to_cpu(c->header.nr_entries);
+
+ return dm_tm_unlock(tm, block);
+}
+
+static int rebalance_children(struct shadow_spine *s,
+ struct dm_btree_info *info, uint64_t key)
+{
+ int i, r, has_left_sibling, has_right_sibling;
+ uint32_t child_entries;
+ struct node *n;
+
+ n = dm_block_data(shadow_current(s));
+
+ if (__le32_to_cpu(n->header.nr_entries) == 1) {
+ struct dm_block *child;
+ dm_block_t b = value64(n, 0);
+
+ r = dm_tm_read_lock(info->tm, b, &btree_node_validator, &child);
+ if (r)
+ return r;
+
+ memcpy(n, dm_block_data(child),
+ dm_bm_block_size(dm_tm_get_bm(info->tm)));
+ r = dm_tm_unlock(info->tm, child);
+ dm_tm_dec(info->tm, dm_block_location(child));
+
+ } else {
+ i = lower_bound(n, key);
+
+ if (i < 0)
+ return -ENODATA;
+
+ r = get_nr_entries(info->tm, value64(n, i), &child_entries);
+ if (r)
+ return r;
+
+ if (child_entries > del_threshold(n))
+ return 0;
+
+ has_left_sibling = i > 0 ? 1 : 0;
+ has_right_sibling =
+ (i >= (__le32_to_cpu(n->header.nr_entries) - 1)) ? 0 : 1;
+
+ if (!has_left_sibling)
+ r = rebalance2(s, info, i);
+
+ else if (!has_right_sibling)
+ r = rebalance2(s, info, i - 1);
+
+ else
+ r = rebalance3(s, info, i - 1);
+ }
+
+ return r;
+}
+
+static int do_leaf(struct node *n, uint64_t key, unsigned *index)
+{
+ int i = lower_bound(n, key);
+
+ if ((i < 0) ||
+ (i >= __le32_to_cpu(n->header.nr_entries)) ||
+ (__le64_to_cpu(n->keys[i]) != key))
+ return -ENODATA;
+
+ *index = i;
+ return 0;
+}
+
+/*
+ * Prepares for removal from one level of the hierarchy. The caller must
+ * actually call delete_at() to remove the entry at index.
+ */
+static int remove_raw(struct shadow_spine *s, struct dm_btree_info *info,
+ struct dm_btree_value_type *vt, dm_block_t root,
+ uint64_t key, unsigned *index)
+{
+ int i = *index, inc, r;
+ struct node *n;
+
+ for (;;) {
+ r = shadow_step(s, root, vt, &inc);
+ if (r < 0)
+ break;
+
+ /* We have to patch up the parent node, ugly, but I don't
+ * see a way to do this automatically as part of the spine
+ * op. */
+ if (shadow_parent(s)) {
+ __le64 location = __cpu_to_le64(dm_block_location(shadow_current(s)));
+ memcpy(value_ptr(dm_block_data(shadow_parent(s)), i, sizeof(uint64_t)),
+ &location, sizeof(__le64));
+ }
+
+ n = dm_block_data(shadow_current(s));
+ if (inc)
+ inc_children(info->tm, n, vt);
+
+ if (__le32_to_cpu(n->header.flags) & LEAF_NODE)
+ return do_leaf(n, key, index);
+
+ else {
+ r = rebalance_children(s, info, key);
+ if (r)
+ break;
+
+ n = dm_block_data(shadow_current(s));
+ if (__le32_to_cpu(n->header.flags) & LEAF_NODE)
+ return do_leaf(n, key, index);
+
+ i = lower_bound(n, key);
+
+ /* We know the key is present, or else
+ * rebalance_children would have returned
+ * -ENODATA
+ */
+ root = value64(n, i);
+ }
+ }
+
+ return r;
+}
+
+int dm_btree_remove(struct dm_btree_info *info, dm_block_t root,
+ uint64_t *keys, dm_block_t *new_root)
+{
+ unsigned level, last_level = info->levels - 1;
+ int index = 0, r = 0;
+ struct shadow_spine spine;
+ struct node *n;
+
+ init_shadow_spine(&spine, info);
+ for (level = 0; level < info->levels; level++) {
+ r = remove_raw(&spine, info,
+ (level == last_level ?
+ &info->value_type : &le64_type_),
+ root, keys[level], (unsigned *)&index);
+ if (r < 0)
+ break;
+
+ n = dm_block_data(shadow_current(&spine));
+ if (level == last_level) {
+ BUG_ON(index < 0 ||
+ index >= __le32_to_cpu(n->header.nr_entries));
+ if (info->value_type.dec)
+ info->value_type.dec(info->value_type.context,
+ value_ptr(n, index, info->value_type.size));
+ delete_at(n, index, info->value_type.size);
+ r = 0;
+ *new_root = shadow_root(&spine);
+
+ } else
+ root = value64(n, index);
+ }
+ exit_shadow_spine(&spine);
+
+ return r;
+}
+EXPORT_SYMBOL_GPL(dm_btree_remove);
+
+/*----------------------------------------------------------------*/
--- /dev/null
+/*
+ * Copyright (C) 2011 Red Hat, Inc. All rights reserved.
+ *
+ * This file is released under the GPL.
+ */
+
+#include "dm-btree-internal.h"
+#include "dm-transaction-manager.h"
+
+#include <linux/device-mapper.h>
+
+#define DM_MSG_PREFIX "btree spine"
+
+/*----------------------------------------------------------------*/
+
+static void node_prepare_for_write(struct dm_block_validator *v,
+ struct dm_block *b,
+ size_t block_size)
+{
+ struct node_header *node = dm_block_data(b);
+
+ node->blocknr = __cpu_to_le64(dm_block_location(b));
+ node->csum = dm_block_csum_data(&node->flags,
+ block_size - sizeof(u32));
+}
+
+static int node_check(struct dm_block_validator *v,
+ struct dm_block *b,
+ size_t block_size)
+{
+ struct node_header *node = dm_block_data(b);
+ __le32 csum;
+
+ if (dm_block_location(b) != __le64_to_cpu(node->blocknr)) {
+ DMERR("node_check failed blocknr %llu wanted %llu",
+ __le64_to_cpu(node->blocknr), dm_block_location(b));
+ return -ENOTBLK;
+ }
+
+ csum = dm_block_csum_data(&node->flags,
+ block_size - sizeof(u32));
+ if (csum != node->csum) {
+ DMERR("node_check failed csum %u wanted %u",
+ __le32_to_cpu(csum), __le32_to_cpu(node->csum));
+ return -EILSEQ;
+ }
+
+ return 0;
+}
+
+struct dm_block_validator btree_node_validator = {
+ .name = "btree_node",
+ .prepare_for_write = node_prepare_for_write,
+ .check = node_check
+};
+
+/*----------------------------------------------------------------*/
+
+static int bn_read_lock(struct dm_btree_info *info, dm_block_t b,
+ struct dm_block **result)
+{
+ return dm_tm_read_lock(info->tm, b, &btree_node_validator, result);
+}
+
+static int bn_shadow(struct dm_btree_info *info, dm_block_t orig,
+ struct dm_btree_value_type *vt,
+ struct dm_block **result, int *inc)
+{
+ int r;
+
+ r = dm_tm_shadow_block(info->tm, orig, &btree_node_validator,
+ result, inc);
+ if (r == 0 && *inc)
+ inc_children(info->tm, dm_block_data(*result), vt);
+
+ return r;
+}
+
+int new_block(struct dm_btree_info *info, struct dm_block **result)
+{
+ return dm_tm_new_block(info->tm, &btree_node_validator, result);
+}
+
+int unlock_for_block(struct dm_btree_info *info, struct dm_block *b)
+{
+ return dm_tm_unlock(info->tm, b);
+}
+
+/*----------------------------------------------------------------*/
+
+void init_ro_spine(struct ro_spine *s, struct dm_btree_info *info)
+{
+ s->info = info;
+ s->count = 0;
+ s->nodes[0] = NULL;
+ s->nodes[1] = NULL;
+}
+
+int exit_ro_spine(struct ro_spine *s)
+{
+ int r = 0, i;
+
+ for (i = 0; i < s->count; i++) {
+ int r2 = unlock_for_block(s->info, s->nodes[i]);
+ if (r2 < 0)
+ r = r2;
+ }
+
+ return r;
+}
+
+int ro_step(struct ro_spine *s, dm_block_t new_child)
+{
+ int r;
+
+ if (s->count == 2) {
+ r = unlock_for_block(s->info, s->nodes[0]);
+ if (r < 0)
+ return r;
+ s->nodes[0] = s->nodes[1];
+ s->count--;
+ }
+
+ r = bn_read_lock(s->info, new_child, s->nodes + s->count);
+ if (r == 0)
+ s->count++;
+
+ return r;
+}
+
+struct node *ro_node(struct ro_spine *s)
+{
+ struct dm_block *n;
+ BUG_ON(!s->count);
+ n = s->nodes[s->count - 1];
+ return dm_block_data(n);
+}
+
+/*----------------------------------------------------------------*/
+
+void init_shadow_spine(struct shadow_spine *s, struct dm_btree_info *info)
+{
+ s->info = info;
+ s->count = 0;
+}
+
+int exit_shadow_spine(struct shadow_spine *s)
+{
+ int r = 0, i;
+
+ for (i = 0; i < s->count; i++) {
+ int r2 = unlock_for_block(s->info, s->nodes[i]);
+ if (r2 < 0)
+ r = r2;
+ }
+
+ return r;
+}
+
+int shadow_step(struct shadow_spine *s, dm_block_t b,
+ struct dm_btree_value_type *vt, int *inc)
+{
+ int r;
+
+ if (s->count == 2) {
+ r = unlock_for_block(s->info, s->nodes[0]);
+ if (r < 0)
+ return r;
+ s->nodes[0] = s->nodes[1];
+ s->count--;
+ }
+
+ r = bn_shadow(s->info, b, vt, s->nodes + s->count, inc);
+ if (r == 0) {
+ if (s->count == 0)
+ s->root = dm_block_location(s->nodes[0]);
+
+ s->count++;
+ }
+
+ return r;
+}
+
+struct dm_block *shadow_current(struct shadow_spine *s)
+{
+ return s->nodes[s->count - 1];
+}
+
+struct dm_block *shadow_parent(struct shadow_spine *s)
+{
+ return s->count == 2 ? s->nodes[0] : NULL;
+}
+
+int shadow_root(struct shadow_spine *s)
+{
+ return s->root;
+}
+
+/*----------------------------------------------------------------*/
--- /dev/null
+/*
+ * Copyright (C) 2011 Red Hat, Inc. All rights reserved.
+ *
+ * This file is released under the GPL.
+ */
+
+#include "dm-btree-internal.h"
+#include "dm-space-map.h"
+#include "dm-transaction-manager.h"
+
+/*----------------------------------------------------------------
+ * Array manipulation
+ *--------------------------------------------------------------*/
+static void array_insert(void *base, size_t elt_size, unsigned nr_elts,
+ unsigned index, void *elt)
+{
+ if (index < nr_elts)
+ memmove(base + (elt_size * (index + 1)),
+ base + (elt_size * index),
+ (nr_elts - index) * elt_size);
+ memcpy(base + (elt_size * index), elt, elt_size);
+}
+
+/*----------------------------------------------------------------*/
+
+/* makes the assumption that no two keys are the same. */
+static int bsearch(struct node *n, uint64_t key, int want_hi)
+{
+ int lo = -1, hi = __le32_to_cpu(n->header.nr_entries);
+
+ while (hi - lo > 1) {
+ int mid = lo + ((hi - lo) / 2);
+ uint64_t mid_key = __le64_to_cpu(n->keys[mid]);
+
+ if (mid_key == key)
+ return mid;
+
+ if (mid_key < key)
+ lo = mid;
+ else
+ hi = mid;
+ }
+
+ return want_hi ? hi : lo;
+}
+
+int lower_bound(struct node *n, uint64_t key)
+{
+ return bsearch(n, key, 0);
+}
+
+void inc_children(struct dm_transaction_manager *tm, struct node *n,
+ struct dm_btree_value_type *vt)
+{
+ unsigned i;
+ uint32_t nr_entries = __le32_to_cpu(n->header.nr_entries);
+
+ if (__le32_to_cpu(n->header.flags) & INTERNAL_NODE)
+ for (i = 0; i < nr_entries; i++)
+ dm_tm_inc(tm, value64(n, i));
+ else if (vt->inc)
+ for (i = 0; i < nr_entries; i++)
+ vt->inc(vt->context,
+ value_ptr(n, i, vt->size));
+}
+
+static void insert_at(size_t value_size, struct node *node, unsigned index,
+ uint64_t key, void *value)
+{
+ uint32_t nr_entries = __le32_to_cpu(node->header.nr_entries);
+
+ BUG_ON(index > nr_entries ||
+ index >= __le32_to_cpu(node->header.max_entries));
+
+ array_insert(node->keys, sizeof(*node->keys), nr_entries, index, &key);
+ array_insert(value_base(node), value_size, nr_entries, index, value);
+ node->header.nr_entries = __cpu_to_le32(nr_entries + 1);
+}
+
+/*----------------------------------------------------------------*/
+
+/*
+ * We want 3n entries (for some n). This works more nicely for repeated
+ * insert remove loops than (2n + 1).
+ */
+static uint32_t calc_max_entries(size_t value_size, size_t block_size)
+{
+ uint32_t total, n;
+ size_t elt_size = sizeof(uint64_t) + value_size; /* key + value */
+
+ block_size -= sizeof(struct node_header);
+ total = block_size / elt_size;
+ n = total / 3; /* rounds down */
+
+ return 3 * n;
+}
+
+int dm_btree_empty(struct dm_btree_info *info, dm_block_t *root)
+{
+ int r;
+ struct dm_block *b;
+ struct node *n;
+ size_t block_size;
+ uint32_t max_entries;
+
+ r = new_block(info, &b);
+ if (r < 0)
+ return r;
+
+ block_size = dm_bm_block_size(dm_tm_get_bm(info->tm));
+ max_entries = calc_max_entries(info->value_type.size, block_size);
+
+ n = (struct node *) dm_block_data(b);
+ memset(n, 0, block_size);
+ n->header.flags = __cpu_to_le32(LEAF_NODE);
+ n->header.nr_entries = __cpu_to_le32(0);
+ n->header.max_entries = __cpu_to_le32(max_entries);
+
+ *root = dm_block_location(b);
+ return unlock_for_block(info, b);
+}
+EXPORT_SYMBOL_GPL(dm_btree_empty);
+
+/*----------------------------------------------------------------*/
+
+/*
+ * Deletion uses a recursive algorithm, since we have limited stack space
+ * we explicitly manage our own stack on the heap.
+ */
+#define MAX_SPINE_DEPTH 64
+struct frame {
+ struct dm_block *b;
+ struct node *n;
+ unsigned level;
+ unsigned nr_children;
+ unsigned current_child;
+};
+
+struct del_stack {
+ struct dm_transaction_manager *tm;
+ int top;
+ struct frame spine[MAX_SPINE_DEPTH];
+};
+
+static void top_frame(struct del_stack *s, struct frame **f)
+{
+ BUG_ON(s->top < 0);
+ *f = s->spine + s->top;
+}
+
+static int unprocessed_frames(struct del_stack *s)
+{
+ return s->top >= 0;
+}
+
+static int push_frame(struct del_stack *s, dm_block_t b, unsigned level)
+{
+ int r;
+ uint32_t ref_count;
+
+ BUG_ON(s->top >= MAX_SPINE_DEPTH);
+
+ r = dm_tm_ref(s->tm, b, &ref_count);
+ if (r)
+ return r;
+
+ if (ref_count > 1)
+ /*
+ * This is a shared node, so we can just decrement it's
+ * reference counter and leave the children.
+ */
+ dm_tm_dec(s->tm, b);
+
+ else {
+ struct frame *f = s->spine + ++s->top;
+
+ r = dm_tm_read_lock(s->tm, b, &btree_node_validator, &f->b);
+ if (r) {
+ s->top--;
+ return r;
+ }
+
+ f->n = dm_block_data(f->b);
+ f->level = level;
+ f->nr_children = __le32_to_cpu(f->n->header.nr_entries);
+ f->current_child = 0;
+ }
+
+ return 0;
+}
+
+static void pop_frame(struct del_stack *s)
+{
+ struct frame *f = s->spine + s->top--;
+
+ dm_tm_dec(s->tm, dm_block_location(f->b));
+ dm_tm_unlock(s->tm, f->b);
+}
+
+int dm_btree_del(struct dm_btree_info *info, dm_block_t root)
+{
+ struct del_stack *s;
+
+ s = kmalloc(sizeof(*s), GFP_KERNEL);
+ if (!s)
+ return -ENOMEM;
+ s->tm = info->tm;
+ s->top = -1;
+
+ push_frame(s, root, 1);
+ while (unprocessed_frames(s)) {
+ int r;
+ uint32_t flags;
+ struct frame *f;
+ dm_block_t b;
+
+ top_frame(s, &f);
+
+ if (f->current_child >= f->nr_children) {
+ pop_frame(s);
+ continue;
+ }
+
+ flags = __le32_to_cpu(f->n->header.flags);
+ if (flags & INTERNAL_NODE) {
+ b = value64(f->n, f->current_child);
+ f->current_child++;
+ r = push_frame(s, b, f->level);
+ if (r)
+ goto bad;
+
+ } else if (f->level != (info->levels - 1)) {
+ b = value64(f->n, f->current_child);
+ f->current_child++;
+ r = push_frame(s, b, f->level + 1);
+ if (r)
+ goto bad;
+
+ } else {
+ if (info->value_type.dec) {
+ unsigned i;
+
+ for (i = 0; i < f->nr_children; i++)
+ info->value_type.dec(info->value_type.context,
+ value_ptr(f->n, i, info->value_type.size));
+ }
+ f->current_child = f->nr_children;
+ }
+ }
+
+ return 0;
+
+bad:
+ /* what happens if we've deleted half a tree? */
+ return -1; /* FIXME: return error code rather than -1? */
+}
+EXPORT_SYMBOL_GPL(dm_btree_del);
+
+int dm_btree_del_gt(struct dm_btree_info *info, dm_block_t root, uint64_t *key,
+ dm_block_t *new_root)
+{
+ /* FIXME: implement */
+ return 0;
+}
+EXPORT_SYMBOL_GPL(dm_btree_del_gt);
+
+/*----------------------------------------------------------------*/
+
+static int btree_lookup_raw(struct ro_spine *s, dm_block_t block, uint64_t key,
+ int (*search_fn)(struct node *, uint64_t),
+ uint64_t *result_key, void *v, size_t value_size)
+{
+ int i, r;
+ uint32_t flags, nr_entries;
+
+ do {
+ r = ro_step(s, block);
+ if (r < 0)
+ return r;
+
+ i = search_fn(ro_node(s), key);
+
+ flags = __le32_to_cpu(ro_node(s)->header.flags);
+ nr_entries = __le32_to_cpu(ro_node(s)->header.nr_entries);
+ if (i < 0 || i >= nr_entries)
+ return -ENODATA;
+
+ if (flags & INTERNAL_NODE)
+ block = value64(ro_node(s), i);
+
+ } while (!(flags & LEAF_NODE));
+
+ *result_key = __le64_to_cpu(ro_node(s)->keys[i]);
+ memcpy(v, value_ptr(ro_node(s), i, value_size), value_size);
+
+ return 0;
+}
+
+int dm_btree_lookup(struct dm_btree_info *info, dm_block_t root,
+ uint64_t *keys, void *value)
+{
+ unsigned level, last_level = info->levels - 1;
+ int r;
+ uint64_t rkey;
+ __le64 internal_value;
+ struct ro_spine spine;
+
+ init_ro_spine(&spine, info);
+ for (level = 0; level < info->levels; level++) {
+ size_t size;
+ void *value_p;
+
+ if (level == last_level) {
+ value_p = value;
+ size = info->value_type.size;
+
+ } else {
+ value_p = &internal_value;
+ size = sizeof(uint64_t);
+ }
+
+ r = btree_lookup_raw(&spine, root, keys[level],
+ lower_bound, &rkey,
+ value_p, size);
+
+ if (r == 0) {
+ if (rkey != keys[level]) {
+ exit_ro_spine(&spine);
+ return -ENODATA;
+ }
+ } else {
+ exit_ro_spine(&spine);
+ return r;
+ }
+
+ root = __le64_to_cpu(internal_value);
+ }
+ exit_ro_spine(&spine);
+
+ return r;
+}
+EXPORT_SYMBOL_GPL(dm_btree_lookup);
+
+/*
+ * Splits a node by creating a sibling node and shifting half the nodes
+ * contents across. Assumes there is a parent node, and it has room for
+ * another child.
+ *
+ * Before:
+ * +--------+
+ * | Parent |
+ * +--------+
+ * |
+ * v
+ * +----------+
+ * | A ++++++ |
+ * +----------+
+ *
+ *
+ * After:
+ * +--------+
+ * | Parent |
+ * +--------+
+ * | |
+ * v +------+
+ * +---------+ |
+ * | A* +++ | v
+ * +---------+ +-------+
+ * | B +++ |
+ * +-------+
+ *
+ * Where A* is a shadow of A.
+ */
+static int btree_split_sibling(struct shadow_spine *s, dm_block_t root,
+ unsigned parent_index, uint64_t key)
+{
+ int ret;
+ size_t size;
+ unsigned nr_left, nr_right;
+ struct dm_block *left, *right, *parent;
+ struct node *l, *r, *p;
+ __le64 location;
+
+ left = shadow_current(s);
+ BUG_ON(!left);
+
+ ret = new_block(s->info, &right);
+ if (ret < 0)
+ return ret;
+
+ l = dm_block_data(left);
+ r = (struct node *) dm_block_data(right);
+
+ nr_left = __le32_to_cpu(l->header.nr_entries) / 2;
+ nr_right = __le32_to_cpu(l->header.nr_entries) - nr_left;
+
+ l->header.nr_entries = __cpu_to_le32(nr_left);
+
+ r->header.flags = l->header.flags;
+ r->header.nr_entries = __cpu_to_le32(nr_right);
+ r->header.max_entries = l->header.max_entries;
+ memcpy(r->keys, l->keys + nr_left, nr_right * sizeof(r->keys[0]));
+
+ size = __le32_to_cpu(l->header.flags) & INTERNAL_NODE ?
+ sizeof(uint64_t) : s->info->value_type.size;
+ memcpy(value_ptr(r, 0, size), value_ptr(l, nr_left, size),
+ size * nr_right);
+
+ /* Patch up the parent */
+ parent = shadow_parent(s);
+ BUG_ON(!parent);
+
+ p = dm_block_data(parent);
+ location = __cpu_to_le64(dm_block_location(left));
+ memcpy(value_ptr(p, parent_index, sizeof(__le64)),
+ &location, sizeof(__le64));
+
+ location = __cpu_to_le64(dm_block_location(right));
+ insert_at(sizeof(__le64), p, parent_index + 1,
+ __le64_to_cpu(r->keys[0]), &location);
+
+ if (key < __le64_to_cpu(r->keys[0])) {
+ unlock_for_block(s->info, right);
+ s->nodes[1] = left;
+ } else {
+ unlock_for_block(s->info, left);
+ s->nodes[1] = right;
+ }
+
+ return 0;
+}
+
+/*
+ * Splits a node by creating two new children beneath the given node.
+ *
+ * Before:
+ * +----------+
+ * | A ++++++ |
+ * +----------+
+ *
+ *
+ * After:
+ * +------------+
+ * | A (shadow) |
+ * +------------+
+ * | |
+ * +------+ +----+
+ * | |
+ * v v
+ * +-------+ +-------+
+ * | B +++ | | C +++ |
+ * +-------+ +-------+
+ */
+static int btree_split_beneath(struct shadow_spine *s, uint64_t key)
+{
+ int ret;
+ size_t size;
+ unsigned nr_left, nr_right;
+ struct dm_block *left, *right, *new_parent;
+ struct node *p, *l, *r;
+ __le64 val;
+
+ new_parent = shadow_current(s);
+ BUG_ON(!new_parent);
+
+ ret = new_block(s->info, &left);
+ if (ret < 0)
+ return ret;
+
+ ret = new_block(s->info, &right);
+ if (ret < 0) {
+ /* FIXME: put left */
+ return ret;
+ }
+
+ p = dm_block_data(new_parent);
+ l = (struct node *) dm_block_data(left);
+ r = (struct node *) dm_block_data(right);
+
+ nr_left = __le32_to_cpu(p->header.nr_entries) / 2;
+ nr_right = __le32_to_cpu(p->header.nr_entries) - nr_left;
+
+ l->header.flags = p->header.flags;
+ l->header.nr_entries = __cpu_to_le32(nr_left);
+ l->header.max_entries = p->header.max_entries;
+
+ r->header.flags = p->header.flags;
+ r->header.nr_entries = __cpu_to_le32(nr_right);
+ r->header.max_entries = p->header.max_entries;
+
+ memcpy(l->keys, p->keys, nr_left * sizeof(p->keys[0]));
+ memcpy(r->keys, p->keys + nr_left, nr_right * sizeof(p->keys[0]));
+
+ size = __le32_to_cpu(p->header.flags) & INTERNAL_NODE ?
+ sizeof(__le64) : s->info->value_type.size;
+ memcpy(value_ptr(l, 0, size), value_ptr(p, 0, size), nr_left * size);
+ memcpy(value_ptr(r, 0, size), value_ptr(p, nr_left, size),
+ nr_right * size);
+
+ /* new_parent should just point to l and r now */
+ p->header.flags = __cpu_to_le32(INTERNAL_NODE);
+ p->header.nr_entries = __cpu_to_le32(2);
+
+ val = __cpu_to_le64(dm_block_location(left));
+ p->keys[0] = l->keys[0];
+ memcpy(value_ptr(p, 0, sizeof(__le64)), &val, sizeof(__le64));
+
+ val = __cpu_to_le64(dm_block_location(right));
+ p->keys[1] = r->keys[0];
+ memcpy(value_ptr(p, 1, sizeof(__le64)), &val, sizeof(__le64));
+
+ /*
+ * rejig the spine. This is ugly, since it knows too
+ * much about the spine
+ */
+ if (s->nodes[0] != new_parent) {
+ unlock_for_block(s->info, s->nodes[0]);
+ s->nodes[0] = new_parent;
+ }
+ if (key < __le64_to_cpu(r->keys[0])) {
+ unlock_for_block(s->info, right);
+ s->nodes[1] = left;
+ } else {
+ unlock_for_block(s->info, left);
+ s->nodes[1] = right;
+ }
+ s->count = 2;
+
+ return 0;
+}
+
+static int btree_insert_raw(struct shadow_spine *s, dm_block_t root,
+ struct dm_btree_value_type *vt,
+ uint64_t key, unsigned *index)
+{
+ int r, i = *index, inc, top = 1;
+ struct node *node;
+
+ for (;;) {
+ r = shadow_step(s, root, vt, &inc);
+ if (r < 0) {
+ /* FIXME: unpick any allocations */
+ return r;
+ }
+
+ node = dm_block_data(shadow_current(s));
+ if (inc)
+ inc_children(s->info->tm, node, vt);
+
+ /*
+ * We have to patch up the parent node, ugly, but I don't
+ * see a way to do this automatically as part of the spine
+ * op.
+ */
+ if (shadow_parent(s) && i >= 0) { /* FIXME: second clause unness. */
+ __le64 location = __cpu_to_le64(dm_block_location(shadow_current(s)));
+ memcpy(value_ptr(dm_block_data(shadow_parent(s)), i, sizeof(uint64_t)),
+ &location, sizeof(__le64));
+ }
+
+ BUG_ON(!shadow_current(s));
+ node = dm_block_data(shadow_current(s));
+
+ if (node->header.nr_entries == node->header.max_entries) {
+ if (top)
+ r = btree_split_beneath(s, key);
+ else
+ r = btree_split_sibling(s, root, i, key);
+
+ if (r < 0)
+ return r;
+ }
+
+ BUG_ON(!shadow_current(s));
+ node = dm_block_data(shadow_current(s));
+
+ i = lower_bound(node, key);
+
+ if (__le32_to_cpu(node->header.flags) & LEAF_NODE)
+ break;
+
+ if (i < 0) {
+ /* change the bounds on the lowest key */
+ node->keys[0] = __cpu_to_le64(key);
+ i = 0;
+ }
+
+ root = value64(node, i);
+ top = 0;
+ }
+
+ if (i < 0 || __le64_to_cpu(node->keys[i]) != key)
+ i++;
+
+ /* we're about to overwrite this value, so undo the increment for it */
+ /* FIXME: shame that inc information is leaking outside the spine.
+ * Plus inc is just plain wrong in the event of a split */
+ if (__le64_to_cpu(node->keys[i]) == key && inc)
+ if (vt->dec)
+ vt->dec(vt->context, value_ptr(node, i, vt->size));
+
+ *index = i;
+ return 0;
+}
+
+static int insert(struct dm_btree_info *info, dm_block_t root,
+ uint64_t *keys, void *value, dm_block_t *new_root,
+ int *inserted)
+{
+ int r, need_insert;
+ unsigned level, index = -1, last_level = info->levels - 1;
+ dm_block_t *block = &root;
+ struct shadow_spine spine;
+ struct node *n;
+ struct dm_btree_value_type le64_type;
+
+ le64_type.context = NULL;
+ le64_type.size = sizeof(__le64);
+ le64_type.inc = NULL;
+ le64_type.dec = NULL;
+ le64_type.equal = NULL;
+
+ init_shadow_spine(&spine, info);
+
+ for (level = 0; level < info->levels; level++) {
+ r = btree_insert_raw(&spine, *block,
+ (level == last_level ?
+ &info->value_type : &le64_type),
+ keys[level], &index);
+ if (r < 0) {
+ exit_shadow_spine(&spine);
+ /* FIXME: avoid block leaks */
+ return r;
+ }
+
+ BUG_ON(!shadow_current(&spine));
+ n = dm_block_data(shadow_current(&spine));
+ need_insert = ((index >= __le32_to_cpu(n->header.nr_entries)) ||
+ (__le64_to_cpu(n->keys[index]) != keys[level]));
+
+ if (level == last_level) {
+ if (need_insert) {
+ if (inserted)
+ *inserted = 1;
+
+ insert_at(info->value_type.size, n, index,
+ keys[level], value);
+ } else {
+ if (inserted)
+ *inserted = 0;
+
+ if (info->value_type.dec &&
+ (!info->value_type.equal ||
+ !info->value_type.equal(
+ info->value_type.context,
+ value_ptr(n, index, info->value_type.size),
+ value))) {
+ info->value_type.dec(info->value_type.context,
+ value_ptr(n, index, info->value_type.size));
+ }
+ memcpy(value_ptr(n, index, info->value_type.size),
+ value, info->value_type.size);
+ }
+ } else {
+ if (need_insert) {
+ dm_block_t new_tree;
+ r = dm_btree_empty(info, &new_tree);
+ if (r < 0) {
+ /* FIXME: avoid block leaks */
+ exit_shadow_spine(&spine);
+ return r;
+ }
+
+ insert_at(sizeof(uint64_t), n, index,
+ keys[level], &new_tree);
+ }
+ }
+
+ if (level < last_level)
+ block = value_ptr(n, index, sizeof(uint64_t));
+ }
+
+ *new_root = shadow_root(&spine);
+ exit_shadow_spine(&spine);
+
+ return 0;
+}
+
+
+int dm_btree_insert(struct dm_btree_info *info, dm_block_t root,
+ uint64_t *keys, void *value, dm_block_t *new_root)
+{
+ return insert(info, root, keys, value, new_root, NULL);
+}
+EXPORT_SYMBOL_GPL(dm_btree_insert);
+
+int dm_btree_insert_notify(struct dm_btree_info *info, dm_block_t root,
+ uint64_t *keys, void *value, dm_block_t *new_root,
+ int *inserted)
+{
+ return insert(info, root, keys, value, new_root, inserted);
+}
+EXPORT_SYMBOL_GPL(dm_btree_insert_notify);
+
+/*----------------------------------------------------------------*/
+
+int dm_btree_clone(struct dm_btree_info *info, dm_block_t root,
+ dm_block_t *clone)
+{
+ int r;
+ struct dm_block *b, *orig_b;
+ struct node *b_node, *orig_node;
+
+ /* Copy the root node */
+ r = new_block(info, &b);
+ if (r < 0)
+ return r;
+
+ r = dm_tm_read_lock(info->tm, root, &btree_node_validator, &orig_b);
+ if (r < 0) {
+ dm_block_t location = dm_block_location(b);
+
+ unlock_for_block(info, b);
+ dm_tm_dec(info->tm, location);
+ }
+
+ *clone = dm_block_location(b);
+ b_node = (struct node *) dm_block_data(b);
+ orig_node = dm_block_data(orig_b);
+
+ memcpy(b_node, orig_node,
+ dm_bm_block_size(dm_tm_get_bm(info->tm)));
+ dm_tm_unlock(info->tm, orig_b);
+ inc_children(info->tm, b_node, &info->value_type);
+ dm_tm_unlock(info->tm, b);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(dm_btree_clone);
+
+/*----------------------------------------------------------------*/
+
+static int find_highest_key(struct ro_spine *s, dm_block_t block,
+ uint64_t *result_key, dm_block_t *next_block)
+{
+ int i, r;
+ uint32_t flags;
+
+ do {
+ r = ro_step(s, block);
+ if (r < 0)
+ return r;
+
+ flags = __le32_to_cpu(ro_node(s)->header.flags);
+ i = __le32_to_cpu(ro_node(s)->header.nr_entries);
+ if (i == 0)
+ return -ENODATA;
+ else
+ i--;
+
+ *result_key = __le64_to_cpu(ro_node(s)->keys[i]);
+ if (next_block || flags & INTERNAL_NODE)
+ block = value64(ro_node(s), i);
+
+ } while (flags & INTERNAL_NODE);
+
+ if (next_block)
+ *next_block = block;
+ return 0;
+}
+
+int dm_btree_find_highest_key(struct dm_btree_info *info, dm_block_t root,
+ uint64_t *result_keys)
+{
+ int r = 0, count = 0, level;
+ struct ro_spine spine;
+
+ init_ro_spine(&spine, info);
+ for (level = 0; level < info->levels; level++) {
+ r = find_highest_key(&spine, root, result_keys + level,
+ level == info->levels - 1 ? NULL : &root);
+ if (r == -ENODATA) {
+ r = 0;
+ break;
+
+ } else if (r)
+ break;
+
+ count++;
+ }
+ exit_ro_spine(&spine);
+
+ return r ? r : count;
+}
+EXPORT_SYMBOL_GPL(dm_btree_find_highest_key);
--- /dev/null
+/*
+ * Copyright (C) 2011 Red Hat, Inc. All rights reserved.
+ *
+ * This file is released under the GPL.
+ */
+#ifndef _LINUX_DM_BTREE_H
+#define _LINUX_DM_BTREE_H
+
+#include "dm-block-manager.h"
+struct dm_transaction_manager;
+
+/*----------------------------------------------------------------*/
+
+/*
+ * Manipulates hierarchical B+ trees with 64-bit keys and arbitrary-sized
+ * values.
+ */
+
+/*
+ * Infomation about the values stored within the btree.
+ */
+struct dm_btree_value_type {
+ void *context;
+
+ /*
+ * The size in bytes of each value.
+ */
+ uint32_t size;
+
+ /*
+ * Any of these methods can be safely set to NULL if you do not
+ * need the corresponding feature.
+ */
+
+ /*
+ * The btree is making a duplicate of the value, for instance
+ * because previously-shared btree nodes have now diverged.
+ * @value argument is the new copy that the copy function may modify.
+ * (Probably it just wants to increment a reference count
+ * somewhere.) This method is _not_ called for insertion of a new
+ * value: It is assumed the ref count is already 1.
+ */
+ void (*inc)(void *context, void *value);
+
+ /*
+ * This value is being deleted. The btree takes care of freeing
+ * the memory pointed to by @value. Often the del function just
+ * needs to decrement a reference count somewhere.
+ */
+ void (*dec)(void *context, void *value);
+
+ /*
+ * A test for equality between two values. When a value is
+ * overwritten with a new one, the old one has the dec method
+ * called _unless_ the new and old value are deemed equal.
+ */
+ int (*equal)(void *context, void *value1, void *value2);
+};
+
+/*
+ * The shape and contents of a btree.
+ */
+struct dm_btree_info {
+ struct dm_transaction_manager *tm;
+
+ /*
+ * Number of nested btrees. (Not the depth of a single tree.)
+ */
+ unsigned levels;
+ struct dm_btree_value_type value_type;
+};
+
+/*
+ * Set up an empty tree. O(1).
+ */
+int dm_btree_empty(struct dm_btree_info *info, dm_block_t *root);
+
+/*
+ * Delete a tree. O(n) - this is the slow one! It can also block, so
+ * please don't call it on an IO path.
+ */
+int dm_btree_del(struct dm_btree_info *info, dm_block_t root);
+
+/*
+ * Delete part of a tree. This is really specific to truncation of
+ * thin devices. It only removes keys from the bottom level-btree that
+ * are greater than key[info->levels - 1].
+ */
+int dm_btree_del_gt(struct dm_btree_info *info, dm_block_t root, uint64_t *key,
+ dm_block_t *new_root);
+
+/*
+ * All the lookup functions return -ENODATA if the key cannot be found.
+ */
+
+/*
+ * Tries to find a key that matches exactly. O(ln(n))
+ */
+int dm_btree_lookup(struct dm_btree_info *info, dm_block_t root,
+ uint64_t *keys, void *value);
+
+/*
+ * Insertion (or overwrite an existing value). O(ln(n))
+ */
+int dm_btree_insert(struct dm_btree_info *info, dm_block_t root,
+ uint64_t *keys, void *value, dm_block_t *new_root);
+
+/*
+ * A variant of insert that indicates whether it actually inserted or just
+ * overwrote. Useful if you're keeping track of the number of entries in a
+ * tree.
+ */
+int dm_btree_insert_notify(struct dm_btree_info *info, dm_block_t root,
+ uint64_t *keys, void *value, dm_block_t *new_root,
+ int *inserted);
+
+/*
+ * Remove a key if present. This doesn't remove empty sub trees. Normally
+ * subtrees represent a separate entity, like a snapshot map, so this is
+ * correct behaviour. O(ln(n)).
+ */
+int dm_btree_remove(struct dm_btree_info *info, dm_block_t root,
+ uint64_t *keys, dm_block_t *new_root);
+
+/*
+ * Clone a tree. O(1)
+ */
+int dm_btree_clone(struct dm_btree_info *info, dm_block_t root, dm_block_t *clone);
+
+/*
+ * Returns < 0 on failure. Otherwise the number of key entries that have
+ * been filled out. Remember trees can have zero entries, and as such have
+ * no highest key.
+ */
+int dm_btree_find_highest_key(struct dm_btree_info *info, dm_block_t root,
+ uint64_t *result_keys);
+
+/*----------------------------------------------------------------*/
+
+#endif /* _LINUX_DM_BTREE_H */
--- /dev/null
+/*
+ * Copyright (C) 2011 Red Hat, Inc. All rights reserved.
+ *
+ * This file is released under the GPL.
+ */
+
+#ifndef DM_SPACE_MAP_COMMON_H
+#define DM_SPACE_MAP_COMMON_H
+
+#include "dm-btree.h"
+
+/*
+ *--------------------------------------------------------------------
+ * Low level disk format
+ *
+ * Bitmap btree
+ * ------------
+ *
+ * Each value stored in the btree is an index_entry. This points to a
+ * block that is used as a bitmap. Within the bitmap hold 2 bits per
+ * entry, which represent UNUSED = 0, REF_COUNT = 1, REF_COUNT = 2 and
+ * REF_COUNT = many.
+ *
+ * Refcount btree
+ * --------------
+ *
+ * Any entry that has a ref count higher than 2 gets entered in the ref
+ * count tree. The leaf values for this tree is the 32-bit ref count.
+ *---------------------------------------------------------------------
+ */
+
+struct index_entry {
+ __le64 blocknr;
+ __le32 nr_free;
+ __le32 none_free_before;
+} __packed;
+
+
+#define MAX_METADATA_BITMAPS 255
+struct metadata_index {
+ __le32 csum;
+ __le32 padding;
+ __le64 blocknr;
+
+ struct index_entry index[MAX_METADATA_BITMAPS];
+} __packed;
+
+struct ll_disk {
+ struct dm_transaction_manager *tm;
+ struct dm_btree_info bitmap_info;
+ struct dm_btree_info ref_count_info;
+
+ uint32_t block_size;
+ uint32_t entries_per_block;
+ dm_block_t nr_blocks;
+ dm_block_t nr_allocated;
+
+ /*
+ * bitmap_root may be a btree root or a simple index.
+ */
+ dm_block_t bitmap_root;
+
+ dm_block_t ref_count_root;
+
+ struct metadata_index mi;
+};
+
+struct sm_root {
+ __le64 nr_blocks;
+ __le64 nr_allocated;
+ __le64 bitmap_root;
+ __le64 ref_count_root;
+} __packed;
+
+#define ENTRIES_PER_BYTE 4
+
+struct bitmap_header {
+ __le32 csum;
+ __le32 not_used;
+ __le64 blocknr;
+} __packed;
+
+/*
+ * These bitops work on a block's worth of bits.
+ */
+unsigned sm_lookup_bitmap(void *addr, unsigned b);
+void sm_set_bitmap(void *addr, unsigned b, unsigned val);
+int sm_find_free(void *addr, unsigned begin, unsigned end, unsigned *result);
+
+void *dm_bitmap_data(struct dm_block *b);
+
+extern struct dm_block_validator dm_sm_bitmap_validator;
+
+#endif /* DM_SPACE_MAP_COMMON_H */
--- /dev/null
+/*
+ * Copyright (C) 2011 Red Hat, Inc. All rights reserved.
+ *
+ * This file is released under the GPL.
+ */
+
+#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/bitops.h>
+#include <linux/device-mapper.h>
+
+#define DM_MSG_PREFIX "space map disk"
+
+/*----------------------------------------------------------------
+ * bitmap validator
+ *--------------------------------------------------------------*/
+static void bitmap_prepare_for_write(struct dm_block_validator *v,
+ struct dm_block *b,
+ size_t block_size)
+{
+ struct bitmap_header *header = dm_block_data(b);
+
+ header->blocknr = __cpu_to_le64(dm_block_location(b));
+ header->csum = dm_block_csum_data(&header->not_used,
+ block_size - sizeof(u32));
+}
+
+static int bitmap_check(struct dm_block_validator *v,
+ struct dm_block *b,
+ size_t block_size)
+{
+ struct bitmap_header *header = dm_block_data(b);
+ __le32 csum;
+
+ if (dm_block_location(b) != __le64_to_cpu(header->blocknr)) {
+ DMERR("bitmap check failed blocknr %llu wanted %llu",
+ __le64_to_cpu(header->blocknr), dm_block_location(b));
+ return -ENOTBLK;
+ }
+
+ csum = dm_block_csum_data(&header->not_used,
+ block_size - sizeof(u32));
+ if (csum != header->csum) {
+ DMERR("bitmap check failed csum %u wanted %u",
+ __le32_to_cpu(csum), __le32_to_cpu(header->csum));
+ return -EILSEQ;
+ }
+
+ return 0;
+}
+
+struct dm_block_validator dm_sm_bitmap_validator = {
+ .name = "sm_bitmap",
+ .prepare_for_write = bitmap_prepare_for_write,
+ .check = bitmap_check
+};
+
+/*----------------------------------------------------------------*/
+
+#define ENTRIES_PER_WORD 32
+#define ENTRIES_SHIFT 5
+
+void *dm_bitmap_data(struct dm_block *b)
+{
+ return dm_block_data(b) + sizeof(struct bitmap_header);
+}
+
+#define WORD_MASK_LOW 0x5555555555555555ULL
+#define WORD_MASK_HIGH 0xAAAAAAAAAAAAAAAAULL
+#define WORD_MASK_ALL 0xFFFFFFFFFFFFFFFFULL
+
+static unsigned bitmap_word_used(void *addr, unsigned b)
+{
+ __le64 *words = (__le64 *) addr;
+ __le64 *w = words + (b >> ENTRIES_SHIFT);
+
+ uint64_t bits = __le64_to_cpu(*w);
+ return ((bits & WORD_MASK_LOW) == WORD_MASK_LOW ||
+ (bits & WORD_MASK_HIGH) == WORD_MASK_HIGH ||
+ (bits & WORD_MASK_ALL) == WORD_MASK_ALL);
+}
+
+unsigned sm_lookup_bitmap(void *addr, unsigned b)
+{
+ __le64 *words = (__le64 *) addr;
+ __le64 *w = words + (b >> ENTRIES_SHIFT);
+
+ b = (b & (ENTRIES_PER_WORD - 1)) << 1;
+ return ((!!test_bit_le(b, (void *) w) << 1)) |
+ (!!test_bit_le(b + 1, (void *) w));
+}
+
+
+void sm_set_bitmap(void *addr, unsigned b, unsigned val)
+{
+ __le64 *words = (__le64 *) addr;
+ __le64 *w = words + (b >> ENTRIES_SHIFT);
+
+ b = (b & (ENTRIES_PER_WORD - 1)) << 1;
+
+ if (val & 2)
+ __set_bit_le(b, (void *) w);
+ else
+ __clear_bit_le(b, (void *) w);
+
+ if (val & 1)
+ __set_bit_le(b + 1, (void *) w);
+ else
+ __clear_bit_le(b + 1, (void *) w);
+}
+
+int sm_find_free(void *addr, unsigned begin, unsigned end,
+ unsigned *result)
+{
+ while (begin < end) {
+ if (!(begin & (ENTRIES_PER_WORD - 1)) &&
+ bitmap_word_used(addr, begin)) {
+ begin += ENTRIES_PER_WORD;
+ continue;
+ }
+
+ if (sm_lookup_bitmap(addr, begin))
+ begin++;
+ else {
+ *result = begin;
+ return 0;
+ }
+ }
+
+ return -ENOSPC;
+}
+
+static int disk_ll_init(struct ll_disk *io, struct dm_transaction_manager *tm)
+{
+ io->tm = tm;
+ io->bitmap_info.tm = tm;
+ io->bitmap_info.levels = 1;
+
+ /*
+ * Because the new bitmap blocks are created via a shadow
+ * operation, the old entry has already had it's reference count
+ * decremented. So we don't need the btree to do any book
+ * keeping.
+ */
+ io->bitmap_info.value_type.size = sizeof(struct index_entry);
+ io->bitmap_info.value_type.inc = NULL;
+ io->bitmap_info.value_type.dec = NULL;
+ io->bitmap_info.value_type.equal = NULL;
+
+ io->ref_count_info.tm = tm;
+ io->ref_count_info.levels = 1;
+ io->ref_count_info.value_type.size = sizeof(uint32_t);
+ io->ref_count_info.value_type.inc = NULL;
+ io->ref_count_info.value_type.dec = NULL;
+ io->ref_count_info.value_type.equal = NULL;
+
+ io->block_size = dm_bm_block_size(dm_tm_get_bm(tm));
+
+ if (io->block_size > (1 << 30)) {
+ DMERR("block size too big to hold bitmaps");
+ return -EINVAL;
+ }
+ io->entries_per_block = (io->block_size - sizeof(struct bitmap_header)) *
+ ENTRIES_PER_BYTE;
+ io->nr_blocks = 0;
+ io->bitmap_root = 0;
+ io->ref_count_root = 0;
+
+ return 0;
+}
+
+static int disk_ll_new(struct ll_disk *io, struct dm_transaction_manager *tm)
+{
+ int r;
+
+ r = disk_ll_init(io, tm);
+ if (r < 0)
+ return r;
+
+ io->nr_blocks = 0;
+ io->nr_allocated = 0;
+ r = dm_btree_empty(&io->bitmap_info, &io->bitmap_root);
+ if (r < 0)
+ return r;
+
+ r = dm_btree_empty(&io->ref_count_info, &io->ref_count_root);
+ if (r < 0) {
+ dm_btree_del(&io->bitmap_info, io->bitmap_root);
+ return r;
+ }
+
+ return 0;
+}
+
+static int disk_ll_extend(struct ll_disk *io, dm_block_t extra_blocks)
+{
+ int r;
+ dm_block_t i, nr_blocks;
+ unsigned old_blocks, blocks;
+
+ nr_blocks = io->nr_blocks + extra_blocks;
+ old_blocks = dm_sector_div_up(io->nr_blocks, io->entries_per_block);
+ blocks = dm_sector_div_up(nr_blocks, io->entries_per_block);
+ for (i = old_blocks; i < blocks; i++) {
+ struct dm_block *b;
+ struct index_entry idx;
+
+ r = dm_tm_new_block(io->tm, &dm_sm_bitmap_validator, &b);
+ if (r < 0)
+ return r;
+ idx.blocknr = __cpu_to_le64(dm_block_location(b));
+
+ r = dm_tm_unlock(io->tm, b);
+ if (r < 0)
+ return r;
+
+ idx.nr_free = __cpu_to_le32(io->entries_per_block);
+ idx.none_free_before = 0;
+
+ r = dm_btree_insert(&io->bitmap_info, io->bitmap_root,
+ &i, &idx, &io->bitmap_root);
+ if (r < 0)
+ return r;
+ }
+
+ io->nr_blocks = nr_blocks;
+ return 0;
+}
+
+static int disk_ll_open(struct ll_disk *ll, struct dm_transaction_manager *tm,
+ void *root, size_t len)
+{
+ int r;
+ struct sm_root *smr = (struct sm_root *) root;
+
+ if (len < sizeof(struct sm_root)) {
+ DMERR("sm_disk root too small");
+ return -ENOMEM;
+ }
+
+ r = disk_ll_init(ll, tm);
+ if (r < 0)
+ return r;
+
+ ll->nr_blocks = __le64_to_cpu(smr->nr_blocks);
+ ll->nr_allocated = __le64_to_cpu(smr->nr_allocated);
+ ll->bitmap_root = __le64_to_cpu(smr->bitmap_root);
+ ll->ref_count_root = __le64_to_cpu(smr->ref_count_root);
+
+ return 0;
+}
+
+static int disk_ll_lookup_bitmap(struct ll_disk *io, dm_block_t b, uint32_t *result)
+{
+ int r;
+ dm_block_t index = b;
+ struct index_entry ie;
+ struct dm_block *blk;
+
+ do_div(index, io->entries_per_block);
+ r = dm_btree_lookup(&io->bitmap_info, io->bitmap_root, &index, &ie);
+ if (r < 0)
+ return r;
+
+ r = dm_tm_read_lock(io->tm, __le64_to_cpu(ie.blocknr),
+ &dm_sm_bitmap_validator, &blk);
+ if (r < 0)
+ return r;
+ *result = sm_lookup_bitmap(dm_bitmap_data(blk),
+ do_div(b, io->entries_per_block));
+ return dm_tm_unlock(io->tm, blk);
+}
+
+static int disk_ll_lookup(struct ll_disk *io, dm_block_t b, uint32_t *result)
+{
+ int r = disk_ll_lookup_bitmap(io, b, result);
+
+ if (r)
+ return r;
+
+ if (*result == 3) {
+ __le32 le_rc;
+ r = dm_btree_lookup(&io->ref_count_info, io->ref_count_root,
+ &b, &le_rc);
+ if (r < 0)
+ return r;
+
+ *result = __le32_to_cpu(le_rc);
+ }
+
+ return r;
+}
+
+static int disk_ll_find_free_block(struct ll_disk *io, dm_block_t begin,
+ dm_block_t end, dm_block_t *result)
+{
+ int r;
+ struct index_entry ie;
+ dm_block_t i, index_begin = begin;
+ dm_block_t index_end = dm_sector_div_up(end, io->entries_per_block);
+
+ begin = do_div(index_begin, io->entries_per_block);
+ for (i = index_begin; i < index_end; i++, begin = 0) {
+ r = dm_btree_lookup(&io->bitmap_info, io->bitmap_root, &i, &ie);
+ if (r < 0)
+ return r;
+
+ if (__le32_to_cpu(ie.nr_free) > 0) {
+ struct dm_block *blk;
+ unsigned position;
+ uint32_t bit_end;
+
+ r = dm_tm_read_lock(io->tm, __le64_to_cpu(ie.blocknr),
+ &dm_sm_bitmap_validator, &blk);
+ if (r < 0)
+ return r;
+
+ bit_end = (i == index_end - 1) ?
+ do_div(end, io->entries_per_block) : io->entries_per_block;
+
+ r = sm_find_free(dm_bitmap_data(blk),
+ max((unsigned)begin,
+ (unsigned)__le32_to_cpu(ie.none_free_before)),
+ bit_end, &position);
+ if (r < 0) {
+ dm_tm_unlock(io->tm, blk);
+ continue;
+ }
+
+ r = dm_tm_unlock(io->tm, blk);
+ if (r < 0)
+ return r;
+
+ *result = i * io->entries_per_block + (dm_block_t) position;
+ return 0;
+ }
+ }
+
+ return -ENOSPC;
+}
+
+static int disk_ll_insert(struct ll_disk *io, dm_block_t b, uint32_t ref_count)
+{
+ int r;
+ uint32_t bit, old;
+ struct dm_block *nb;
+ dm_block_t index = b;
+ struct index_entry ie;
+ void *bm;
+ int inc;
+
+ do_div(index, io->entries_per_block);
+ r = dm_btree_lookup(&io->bitmap_info, io->bitmap_root, &index, &ie);
+ if (r < 0)
+ return r;
+
+ r = dm_tm_shadow_block(io->tm, __le64_to_cpu(ie.blocknr),
+ &dm_sm_bitmap_validator, &nb, &inc);
+ if (r < 0) {
+ DMERR("dm_tm_shadow_block() failed");
+ return r;
+ }
+ ie.blocknr = __cpu_to_le64(dm_block_location(nb));
+
+ bm = dm_bitmap_data(nb);
+ bit = do_div(b, io->entries_per_block);
+ old = sm_lookup_bitmap(bm, bit);
+
+ if (ref_count <= 2) {
+ sm_set_bitmap(bm, bit, ref_count);
+
+ if (old > 2) {
+ r = dm_btree_remove(&io->ref_count_info, io->ref_count_root,
+ &b, &io->ref_count_root);
+ if (r) {
+ dm_tm_unlock(io->tm, nb);
+ return r;
+ }
+ }
+ } else {
+ __le32 le_rc = __cpu_to_le32(ref_count);
+ sm_set_bitmap(bm, bit, 3);
+ r = dm_btree_insert(&io->ref_count_info, io->ref_count_root,
+ &b, &le_rc, &io->ref_count_root);
+ if (r < 0) {
+ dm_tm_unlock(io->tm, nb);
+ DMERR("ref count insert failed");
+ return r;
+ }
+ }
+
+ r = dm_tm_unlock(io->tm, nb);
+ if (r < 0)
+ return r;
+
+ if (ref_count && !old) {
+ io->nr_allocated++;
+ ie.nr_free = __cpu_to_le32(__le32_to_cpu(ie.nr_free) - 1);
+ if (__le32_to_cpu(ie.none_free_before) == b)
+ ie.none_free_before = __cpu_to_le32(b + 1);
+
+ } else if (old && !ref_count) {
+ io->nr_allocated--;
+ ie.nr_free = __cpu_to_le32(__le32_to_cpu(ie.nr_free) + 1);
+ ie.none_free_before = __cpu_to_le32(min((dm_block_t) __le32_to_cpu(ie.none_free_before), b));
+ }
+
+ r = dm_btree_insert(&io->bitmap_info, io->bitmap_root,
+ &index, &ie, &io->bitmap_root);
+ if (r < 0)
+ return r;
+
+ return 0;
+}
+
+static int disk_ll_inc(struct ll_disk *ll, dm_block_t b)
+{
+ int r;
+ uint32_t rc;
+
+ r = disk_ll_lookup(ll, b, &rc);
+ if (r)
+ return r;
+
+ return disk_ll_insert(ll, b, rc + 1);
+}
+
+static int disk_ll_dec(struct ll_disk *ll, dm_block_t b)
+{
+ int r;
+ uint32_t rc;
+
+ r = disk_ll_lookup(ll, b, &rc);
+ if (r)
+ return r;
+
+ if (!rc)
+ return -EINVAL;
+
+ return disk_ll_insert(ll, b, rc - 1);
+}
+
+/*----------------------------------------------------------------
+ * Space map interface.
+ *--------------------------------------------------------------*/
+struct sm_disk {
+ struct dm_space_map sm;
+
+ struct ll_disk ll;
+};
+
+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 disk_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->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->ll.nr_blocks - smd->ll.nr_allocated;
+ 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 disk_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)
+{
+ struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
+ return disk_ll_insert(&smd->ll, b, count);
+}
+
+static int sm_disk_inc_block(struct dm_space_map *sm, dm_block_t b)
+{
+ struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
+ return disk_ll_inc(&smd->ll, b);
+}
+
+static int sm_disk_dec_block(struct dm_space_map *sm, dm_block_t b)
+{
+ struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
+ return disk_ll_dec(&smd->ll, b);
+}
+
+static int sm_disk_new_block(struct dm_space_map *sm, dm_block_t *b)
+{
+ int r;
+ struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
+
+ /* FIXME: we should start the search where we left off */
+ r = disk_ll_find_free_block(&smd->ll, 0, smd->ll.nr_blocks, b);
+ if (r)
+ return r;
+
+ return disk_ll_inc(&smd->ll, *b);
+}
+
+static int sm_disk_commit(struct dm_space_map *sm)
+{
+ return 0;
+}
+
+static int sm_disk_root_size(struct dm_space_map *sm, size_t *result)
+{
+ *result = sizeof(struct sm_root);
+ return 0;
+}
+
+static int sm_disk_copy_root(struct dm_space_map *sm, void *where, size_t max)
+{
+ struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
+ struct sm_root root;
+
+ root.nr_blocks = __cpu_to_le64(smd->ll.nr_blocks);
+ root.nr_allocated = __cpu_to_le64(smd->ll.nr_allocated);
+ root.bitmap_root = __cpu_to_le64(smd->ll.bitmap_root);
+ root.ref_count_root = __cpu_to_le64(smd->ll.ref_count_root);
+
+ if (max < sizeof(root))
+ return -ENOSPC;
+
+ memcpy(where, &root, sizeof(root));
+ 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
+};
+
+struct dm_space_map *dm_sm_disk_create(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);
+
+ memcpy(&smd->sm, &ops_, sizeof(smd->sm));
+
+ r = disk_ll_new(&smd->ll, tm);
+ if (r)
+ return ERR_PTR(r);
+
+ r = disk_ll_extend(&smd->ll, nr_blocks);
+ if (r)
+ return ERR_PTR(r);
+
+ r = sm_disk_commit(&smd->sm);
+ if (r)
+ return ERR_PTR(r);
+
+ return &smd->sm;
+}
+EXPORT_SYMBOL_GPL(dm_sm_disk_create);
+
+struct dm_space_map *dm_sm_disk_open(struct dm_transaction_manager *tm,
+ void *root, size_t len)
+{
+ int r;
+ struct sm_disk *smd;
+
+ smd = kmalloc(sizeof(*smd), GFP_KERNEL);
+ if (!smd)
+ return ERR_PTR(-ENOMEM);
+
+ memcpy(&smd->sm, &ops_, sizeof(smd->sm));
+
+ r = disk_ll_open(&smd->ll, tm, root, len);
+ if (r)
+ return ERR_PTR(r);
+
+ r = sm_disk_commit(&smd->sm);
+ if (r)
+ return ERR_PTR(r);
+
+ return &smd->sm;
+}
+EXPORT_SYMBOL_GPL(dm_sm_disk_open);
--- /dev/null
+/*
+ * Copyright (C) 2011 Red Hat, Inc. All rights reserved.
+ *
+ * This file is released under the GPL.
+ */
+
+#ifndef _LINUX_DM_SPACE_MAP_DISK_H
+#define _LINUX_DM_SPACE_MAP_DISK_H
+
+#include "dm-block-manager.h"
+
+struct dm_space_map;
+struct dm_transaction_manager;
+
+/*
+ * Unfortunately we have to use two-phase construction due to the cycle
+ * between the tm and sm.
+ */
+struct dm_space_map *dm_sm_disk_create(struct dm_transaction_manager *tm,
+ dm_block_t nr_blocks);
+
+struct dm_space_map *dm_sm_disk_open(struct dm_transaction_manager *tm,
+ void *root, size_t len);
+
+#endif /* _LINUX_DM_SPACE_MAP_DISK_H */
--- /dev/null
+/*
+ * Copyright (C) 2011 Red Hat, Inc. All rights reserved.
+ *
+ * This file is released under the GPL.
+ */
+
+#include "dm-space-map.h"
+#include "dm-space-map-common.h"
+#include "dm-space-map-metadata.h"
+
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/bitops.h>
+#include <linux/device-mapper.h>
+
+#define DM_MSG_PREFIX "space map metadata"
+
+/*----------------------------------------------------------------
+ * index validator
+ *--------------------------------------------------------------*/
+static void index_prepare_for_write(struct dm_block_validator *v,
+ struct dm_block *b,
+ size_t block_size)
+{
+ struct metadata_index *mi = dm_block_data(b);
+ mi->blocknr = __cpu_to_le64(dm_block_location(b));
+ mi->csum = dm_block_csum_data(&mi->padding,
+ block_size - sizeof(__le32));
+}
+
+static int index_check(struct dm_block_validator *v,
+ struct dm_block *b,
+ size_t block_size)
+{
+ struct metadata_index *mi = dm_block_data(b);
+ __le32 csum;
+
+ if (dm_block_location(b) != __le64_to_cpu(mi->blocknr)) {
+ DMERR("index_check failed blocknr %llu wanted %llu",
+ __le64_to_cpu(mi->blocknr), dm_block_location(b));
+ return -ENOTBLK;
+ }
+
+ csum = dm_block_csum_data(&mi->padding,
+ block_size - sizeof(__le32));
+ if (csum != mi->csum) {
+ DMERR("index_check failed csum %u wanted %u",
+ __le32_to_cpu(csum), __le32_to_cpu(mi->csum));
+ return -EILSEQ;
+ }
+
+ return 0;
+}
+
+static struct dm_block_validator index_validator_ = {
+ .name = "index",
+ .prepare_for_write = index_prepare_for_write,
+ .check = index_check
+};
+
+/*----------------------------------------------------------------
+ * low level disk ops
+ *--------------------------------------------------------------*/
+static int metadata_ll_init(struct ll_disk *ll, struct dm_transaction_manager *tm)
+{
+ ll->tm = tm;
+
+ ll->ref_count_info.tm = tm;
+ ll->ref_count_info.levels = 1;
+ ll->ref_count_info.value_type.size = sizeof(uint32_t);
+ ll->ref_count_info.value_type.inc = NULL;
+ ll->ref_count_info.value_type.dec = NULL;
+ ll->ref_count_info.value_type.equal = NULL;
+
+ ll->block_size = dm_bm_block_size(dm_tm_get_bm(tm));
+
+ if (ll->block_size > (1 << 30)) {
+ DMERR("block size too big to hold bitmaps");
+ return -EINVAL;
+ }
+ ll->entries_per_block = (ll->block_size - sizeof(struct bitmap_header)) *
+ ENTRIES_PER_BYTE;
+ ll->nr_blocks = 0;
+ ll->bitmap_root = 0;
+ ll->ref_count_root = 0;
+
+ return 0;
+}
+
+static int metadata_ll_new(struct ll_disk *ll, struct dm_transaction_manager *tm,
+ dm_block_t nr_blocks)
+{
+ int r;
+ dm_block_t i;
+ unsigned blocks;
+ struct dm_block *index_block;
+
+ r = metadata_ll_init(ll, tm);
+ if (r < 0)
+ return r;
+
+ ll->nr_blocks = nr_blocks;
+ ll->nr_allocated = 0;
+
+ blocks = dm_sector_div_up(nr_blocks, ll->entries_per_block);
+ for (i = 0; i < blocks; i++) {
+ struct dm_block *b;
+ struct index_entry *idx = ll->mi.index + i;
+
+ r = dm_tm_new_block(tm, &dm_sm_bitmap_validator, &b);
+ if (r < 0)
+ return r;
+ idx->blocknr = __cpu_to_le64(dm_block_location(b));
+
+ r = dm_tm_unlock(tm, b);
+ if (r < 0)
+ return r;
+
+ idx->nr_free = __cpu_to_le32(ll->entries_per_block);
+ idx->none_free_before = 0;
+ }
+
+ /* write the index */
+ r = dm_tm_new_block(tm, &index_validator_, &index_block);
+ if (r)
+ return r;
+ ll->bitmap_root = dm_block_location(index_block);
+ memcpy(dm_block_data(index_block), &ll->mi, sizeof(ll->mi));
+ r = dm_tm_unlock(tm, index_block);
+ if (r)
+ return r;
+
+ r = dm_btree_empty(&ll->ref_count_info, &ll->ref_count_root);
+ if (r < 0)
+ return r;
+
+ return 0;
+}
+
+static int metadata_ll_open(struct ll_disk *ll, struct dm_transaction_manager *tm,
+ void *root, size_t len)
+{
+ int r;
+ struct sm_root *smr = (struct sm_root *) root;
+ struct dm_block *block;
+
+ if (len < sizeof(struct sm_root)) {
+ DMERR("sm_disk root too small");
+ return -ENOMEM;
+ }
+
+ r = metadata_ll_init(ll, tm);
+ if (r < 0)
+ return r;
+
+ ll->nr_blocks = __le64_to_cpu(smr->nr_blocks);
+ ll->nr_allocated = __le64_to_cpu(smr->nr_allocated);
+ ll->bitmap_root = __le64_to_cpu(smr->bitmap_root);
+
+ r = dm_tm_read_lock(tm, __le64_to_cpu(smr->bitmap_root),
+ &index_validator_, &block);
+ if (r)
+ return r;
+ memcpy(&ll->mi, dm_block_data(block), sizeof(ll->mi));
+ r = dm_tm_unlock(tm, block);
+ if (r)
+ return r;
+
+ ll->ref_count_root = __le64_to_cpu(smr->ref_count_root);
+ return 0;
+}
+
+static int metadata_ll_lookup_bitmap(struct ll_disk *ll, dm_block_t b, uint32_t *result)
+{
+ int r;
+ dm_block_t index = b;
+ struct index_entry *ie;
+ struct dm_block *blk;
+
+ b = do_div(index, ll->entries_per_block);
+ ie = ll->mi.index + index;
+
+ r = dm_tm_read_lock(ll->tm, __le64_to_cpu(ie->blocknr),
+ &dm_sm_bitmap_validator, &blk);
+ if (r < 0)
+ return r;
+ *result = sm_lookup_bitmap(dm_bitmap_data(blk), b);
+ return dm_tm_unlock(ll->tm, blk);
+}
+
+static int metadata_ll_lookup(struct ll_disk *ll, dm_block_t b, uint32_t *result)
+{
+ int r = metadata_ll_lookup_bitmap(ll, b, result);
+
+ if (r)
+ return r;
+
+ if (*result == 3) {
+ __le32 le_rc;
+ r = dm_btree_lookup(&ll->ref_count_info, ll->ref_count_root,
+ &b, &le_rc);
+ if (r < 0)
+ return r;
+
+ *result = __le32_to_cpu(le_rc);
+ }
+
+ return r;
+}
+
+static int metadata_ll_find_free_block(struct ll_disk *ll, dm_block_t begin,
+ dm_block_t end, dm_block_t *result)
+{
+ int r;
+ struct index_entry *ie;
+ dm_block_t i, index_begin = begin;
+ dm_block_t index_end = dm_sector_div_up(end, ll->entries_per_block);
+
+ /* FIXME: use shifts */
+ begin = do_div(index_begin, ll->entries_per_block);
+ end = do_div(end, ll->entries_per_block);
+
+ for (i = index_begin; i < index_end; i++, begin = 0) {
+ ie = ll->mi.index + i;
+
+ if (__le32_to_cpu(ie->nr_free) > 0) {
+ struct dm_block *blk;
+ unsigned position;
+ uint32_t bit_end;
+
+ r = dm_tm_read_lock(ll->tm, __le64_to_cpu(ie->blocknr),
+ &dm_sm_bitmap_validator, &blk);
+ if (r < 0)
+ return r;
+
+ bit_end = (i == index_end - 1) ?
+ end : ll->entries_per_block;
+
+ r = sm_find_free(dm_bitmap_data(blk), begin,
+ bit_end, &position);
+ if (r < 0) {
+ dm_tm_unlock(ll->tm, blk);
+ return r; /* avoiding retry (FIXME: explain why) */
+ }
+
+ r = dm_tm_unlock(ll->tm, blk);
+ if (r < 0)
+ return r;
+
+ *result = i * ll->entries_per_block +
+ (dm_block_t) position;
+ return 0;
+ }
+ }
+
+ return -ENOSPC;
+}
+
+static int metadata_ll_insert(struct ll_disk *ll, dm_block_t b, uint32_t ref_count)
+{
+ int r;
+ uint32_t bit, old;
+ struct dm_block *nb;
+ dm_block_t index = b;
+ struct index_entry *ie;
+ void *bm;
+ int inc;
+
+ bit = do_div(index, ll->entries_per_block);
+ ie = ll->mi.index + index;
+
+ r = dm_tm_shadow_block(ll->tm, __le64_to_cpu(ie->blocknr),
+ &dm_sm_bitmap_validator, &nb, &inc);
+ if (r < 0) {
+ DMERR("dm_tm_shadow_block() failed");
+ return r;
+ }
+ ie->blocknr = __cpu_to_le64(dm_block_location(nb));
+
+ bm = dm_bitmap_data(nb);
+ old = sm_lookup_bitmap(bm, bit);
+
+ if (ref_count <= 2) {
+ sm_set_bitmap(bm, bit, ref_count);
+
+ r = dm_tm_unlock(ll->tm, nb);
+ if (r < 0)
+ return r;
+
+ if (old > 2) {
+ r = dm_btree_remove(&ll->ref_count_info,
+ ll->ref_count_root,
+ &b, &ll->ref_count_root);
+ if (r) {
+ sm_set_bitmap(bm, bit, old);
+ return r;
+ }
+ }
+ } else {
+ __le32 le_rc = __cpu_to_le32(ref_count);
+ sm_set_bitmap(bm, bit, 3);
+ r = dm_tm_unlock(ll->tm, nb);
+ if (r < 0)
+ return r;
+
+ r = dm_btree_insert(&ll->ref_count_info, ll->ref_count_root,
+ &b, &le_rc, &ll->ref_count_root);
+ if (r < 0) {
+ /* FIXME: release shadow? or assume the whole transaction will be ditched */
+ DMERR("ref count insert failed");
+ return r;
+ }
+ }
+
+ if (ref_count && !old) {
+ ll->nr_allocated++;
+ ie->nr_free = __cpu_to_le32(__le32_to_cpu(ie->nr_free) - 1);
+ if (__le32_to_cpu(ie->none_free_before) == b)
+ ie->none_free_before = __cpu_to_le32(b + 1);
+
+ } else if (old && !ref_count) {
+ ll->nr_allocated--;
+ ie->nr_free = __cpu_to_le32(__le32_to_cpu(ie->nr_free) + 1);
+ ie->none_free_before = __cpu_to_le32(min((dm_block_t) __le32_to_cpu(ie->none_free_before), b));
+ }
+
+ return 0;
+}
+
+static int metadata_ll_inc(struct ll_disk *ll, dm_block_t b)
+{
+ int r;
+ uint32_t rc;
+
+ r = metadata_ll_lookup(ll, b, &rc);
+ if (r)
+ return r;
+
+ return metadata_ll_insert(ll, b, rc + 1);
+}
+
+static int metadata_ll_dec(struct ll_disk *ll, dm_block_t b)
+{
+ int r;
+ uint32_t rc;
+
+ r = metadata_ll_lookup(ll, b, &rc);
+ if (r)
+ return r;
+
+ if (!rc)
+ return -EINVAL;
+
+ return metadata_ll_insert(ll, b, rc - 1);
+}
+
+static int metadata_ll_commit(struct ll_disk *ll)
+{
+ int r, inc;
+ struct dm_block *b;
+
+ r = dm_tm_shadow_block(ll->tm, ll->bitmap_root,
+ &index_validator_, &b, &inc);
+ if (r)
+ return r;
+
+ memcpy(dm_block_data(b), &ll->mi, sizeof(ll->mi));
+ ll->bitmap_root = dm_block_location(b);
+ return dm_tm_unlock(ll->tm, b);
+}
+
+/*----------------------------------------------------------------
+ * Space map interface.
+ *
+ * The low level disk format is written using the standard btree and
+ * transaction manager. This means that performing disk operations may
+ * cause us to recurse into the space map in order to allocate new blocks.
+ * For this reason we have a pool of pre-allocated blocks large enough to
+ * service any metadata_ll_disk operation.
+ *--------------------------------------------------------------*/
+
+/*
+ * FIXME: we should calculate this based on the size of the device.
+ * Only the metadata space map needs this functionality.
+ */
+#define MAX_RECURSIVE_ALLOCATIONS 1024
+
+enum block_op_type {
+ BOP_INC,
+ BOP_DEC
+};
+
+struct block_op {
+ enum block_op_type type;
+ dm_block_t block;
+};
+
+struct sm_metadata {
+ struct dm_space_map sm;
+
+ struct ll_disk ll;
+ struct ll_disk old_ll;
+
+ dm_block_t begin;
+
+ unsigned recursion_count;
+ unsigned allocated_this_transaction;
+ unsigned nr_uncommitted;
+ struct block_op uncommitted[MAX_RECURSIVE_ALLOCATIONS];
+};
+
+static int add_bop(struct sm_metadata *smm, enum block_op_type type, dm_block_t b)
+{
+ struct block_op *op;
+
+ if (smm->nr_uncommitted == MAX_RECURSIVE_ALLOCATIONS) {
+ BUG();
+ return -1;
+ }
+
+ op = smm->uncommitted + smm->nr_uncommitted++;
+ op->type = type;
+ op->block = b;
+ return 0;
+}
+
+static int commit_bop(struct sm_metadata *smm, struct block_op *op)
+{
+ int r = 0;
+
+ switch (op->type) {
+ case BOP_INC:
+ r = metadata_ll_inc(&smm->ll, op->block);
+ break;
+
+ case BOP_DEC:
+ r = metadata_ll_dec(&smm->ll, op->block);
+ break;
+ }
+
+ return r;
+}
+
+static void in(struct sm_metadata *smm)
+{
+ smm->recursion_count++;
+}
+
+static void out(struct sm_metadata *smm)
+{
+ int r = 0;
+ BUG_ON(!smm->recursion_count);
+
+ if (smm->recursion_count == 1 && smm->nr_uncommitted) {
+ while (smm->nr_uncommitted && !r) {
+ smm->nr_uncommitted--;
+ r = commit_bop(smm, smm->uncommitted +
+ smm->nr_uncommitted);
+ }
+ }
+
+ smm->recursion_count--;
+}
+
+static void no_recurse(struct sm_metadata *smm)
+{
+ BUG_ON(smm->recursion_count);
+}
+
+static int recursing(struct sm_metadata *smm)
+{
+ return smm->recursion_count;
+}
+
+static void sm_metadata_destroy(struct dm_space_map *sm)
+{
+ struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
+ kfree(smm);
+}
+
+static int sm_metadata_extend(struct dm_space_map *sm, dm_block_t extra_blocks)
+{
+ BUG();
+ return -1;
+}
+
+static int sm_metadata_get_nr_blocks(struct dm_space_map *sm, dm_block_t *count)
+{
+ struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
+ *count = smm->ll.nr_blocks;
+ return 0;
+}
+
+static int sm_metadata_get_nr_free(struct dm_space_map *sm, dm_block_t *count)
+{
+ struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
+
+ *count = smm->old_ll.nr_blocks - smm->old_ll.nr_allocated -
+ smm->allocated_this_transaction;
+ return 0;
+}
+
+static int sm_metadata_get_count(struct dm_space_map *sm, dm_block_t b,
+ uint32_t *result)
+{
+ int r, i;
+ struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
+ unsigned adjustment = 0;
+
+ /*
+ * we may have some uncommitted adjustments to add. This list
+ * should always be really short.
+ */
+ for (i = 0; i < smm->nr_uncommitted; i++) {
+ struct block_op *op = smm->uncommitted + i;
+ if (op->block == b)
+ switch (op->type) {
+ case BOP_INC:
+ adjustment++;
+ break;
+
+ case BOP_DEC:
+ adjustment--;
+ break;
+ }
+ }
+
+ r = metadata_ll_lookup(&smm->ll, b, result);
+ if (r)
+ return r;
+ *result += adjustment;
+
+ return 0;
+}
+
+static int sm_metadata_count_is_more_than_one(struct dm_space_map *sm,
+ dm_block_t b, int *result)
+{
+ int r, i, adjustment = 0;
+ struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
+ uint32_t rc;
+
+ /*
+ * we may have some uncommitted adjustments to add. This list
+ * should always be really short.
+ */
+ for (i = 0; i < smm->nr_uncommitted; i++) {
+ struct block_op *op = smm->uncommitted + i;
+ if (op->block == b)
+ switch (op->type) {
+ case BOP_INC:
+ adjustment++;
+ break;
+
+ case BOP_DEC:
+ adjustment--;
+ break;
+ }
+ }
+
+ if (adjustment > 1) {
+ *result = 1;
+ return 0;
+ }
+
+ r = metadata_ll_lookup_bitmap(&smm->ll, b, &rc);
+ if (r)
+ return r;
+
+ if (rc == 3)
+ /* we err on the side of caution, and always return true */
+ *result = 1;
+ else
+ *result = rc + adjustment > 1;
+
+ return 0;
+}
+
+static int sm_metadata_set_count(struct dm_space_map *sm, dm_block_t b,
+ uint32_t count)
+{
+ int r;
+ struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
+
+ no_recurse(smm);
+
+ in(smm);
+ r = metadata_ll_insert(&smm->ll, b, count);
+ out(smm);
+ return r;
+}
+
+static int sm_metadata_inc_block(struct dm_space_map *sm, dm_block_t b)
+{
+ int r;
+ struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
+
+ if (recursing(smm))
+ r = add_bop(smm, BOP_INC, b);
+
+ else {
+ in(smm);
+ r = metadata_ll_inc(&smm->ll, b);
+ out(smm);
+ }
+ return r;
+}
+
+static int sm_metadata_dec_block(struct dm_space_map *sm, dm_block_t b)
+{
+ int r;
+ struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
+
+ if (recursing(smm))
+ r = add_bop(smm, BOP_DEC, b);
+
+ else {
+ in(smm);
+ r = metadata_ll_dec(&smm->ll, b);
+ out(smm);
+ }
+ return r;
+}
+
+static int sm_metadata_new_block(struct dm_space_map *sm, dm_block_t *b)
+{
+ int r;
+ struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
+
+ r = metadata_ll_find_free_block(&smm->old_ll, smm->begin, smm->old_ll.nr_blocks, b);
+ if (r)
+ return r;
+
+ smm->begin = *b + 1;
+
+ if (recursing(smm))
+ r = add_bop(smm, BOP_INC, *b);
+
+ else {
+ in(smm);
+ r = metadata_ll_inc(&smm->ll, *b);
+ out(smm);
+ }
+
+ if (!r)
+ smm->allocated_this_transaction++;
+ return r;
+}
+
+static int sm_metadata_commit(struct dm_space_map *sm)
+{
+ int r;
+ struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
+
+ memcpy(&smm->old_ll, &smm->ll, sizeof(smm->old_ll));
+
+ r = metadata_ll_commit(&smm->ll);
+ if (r)
+ return r;
+
+ memcpy(&smm->old_ll, &smm->ll, sizeof(smm->old_ll));
+ smm->begin = 0;
+ smm->allocated_this_transaction = 0;
+ return 0;
+}
+
+static int sm_metadata_root_size(struct dm_space_map *sm, size_t *result)
+{
+ *result = sizeof(struct sm_root);
+ return 0;
+}
+
+static int sm_metadata_copy_root(struct dm_space_map *sm, void *where, size_t max)
+{
+ struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
+ struct sm_root root;
+
+ root.nr_blocks = __cpu_to_le64(smm->ll.nr_blocks);
+ root.nr_allocated = __cpu_to_le64(smm->ll.nr_allocated);
+ root.bitmap_root = __cpu_to_le64(smm->ll.bitmap_root);
+ root.ref_count_root = __cpu_to_le64(smm->ll.ref_count_root);
+
+ if (max < sizeof(root))
+ return -ENOSPC;
+
+ memcpy(where, &root, sizeof(root));
+
+ return 0;
+}
+
+static struct dm_space_map ops_ = {
+ .destroy = sm_metadata_destroy,
+ .extend = sm_metadata_extend,
+ .get_nr_blocks = sm_metadata_get_nr_blocks,
+ .get_nr_free = sm_metadata_get_nr_free,
+ .get_count = sm_metadata_get_count,
+ .count_is_more_than_one = sm_metadata_count_is_more_than_one,
+ .set_count = sm_metadata_set_count,
+ .inc_block = sm_metadata_inc_block,
+ .dec_block = sm_metadata_dec_block,
+ .new_block = sm_metadata_new_block,
+ .commit = sm_metadata_commit,
+ .root_size = sm_metadata_root_size,
+ .copy_root = sm_metadata_copy_root
+};
+
+/*----------------------------------------------------------------*/
+
+/*
+ * When a new space map is created, that manages it's own space. We use
+ * this tiny bootstrap allocator.
+ */
+static void sm_bootstrap_destroy(struct dm_space_map *sm)
+{
+ BUG();
+}
+
+static int sm_bootstrap_extend(struct dm_space_map *sm, dm_block_t extra_blocks)
+{
+ BUG();
+ return -1;
+}
+
+static int sm_bootstrap_get_nr_blocks(struct dm_space_map *sm, dm_block_t *count)
+{
+ struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
+ return smm->ll.nr_blocks;
+}
+
+static int sm_bootstrap_get_nr_free(struct dm_space_map *sm, dm_block_t *count)
+{
+ struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
+ *count = smm->ll.nr_blocks - smm->begin;
+ return 0;
+}
+
+static int sm_bootstrap_get_count(struct dm_space_map *sm, dm_block_t b,
+ uint32_t *result)
+{
+ struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
+ return b < smm->begin ? 1 : 0;
+}
+
+static int sm_bootstrap_count_is_more_than_one(struct dm_space_map *sm,
+ dm_block_t b, int *result)
+{
+ *result = 0;
+ return 0;
+}
+
+static int sm_bootstrap_set_count(struct dm_space_map *sm, dm_block_t b,
+ uint32_t count)
+{
+ BUG();
+ return -1;
+}
+
+static int sm_bootstrap_new_block(struct dm_space_map *sm, dm_block_t *b)
+{
+ struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
+
+ /*
+ * We know the entire device is unused.
+ */
+ if (smm->begin == smm->ll.nr_blocks)
+ return -ENOSPC;
+
+ *b = smm->begin++;
+ return 0;
+}
+
+static int sm_bootstrap_inc_block(struct dm_space_map *sm, dm_block_t b)
+{
+ struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
+ return add_bop(smm, BOP_INC, b);
+}
+
+static int sm_bootstrap_dec_block(struct dm_space_map *sm, dm_block_t b)
+{
+ struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
+ return add_bop(smm, BOP_DEC, b);
+}
+
+static int sm_bootstrap_commit(struct dm_space_map *sm)
+{
+ return 0;
+}
+
+static int sm_bootstrap_root_size(struct dm_space_map *sm, size_t *result)
+{
+ BUG();
+ return -1;
+}
+
+static int sm_bootstrap_copy_root(struct dm_space_map *sm, void *where,
+ size_t max)
+{
+ BUG();
+ return -1;
+}
+
+static struct dm_space_map bootstrap_ops_ = {
+ .destroy = sm_bootstrap_destroy,
+ .extend = sm_bootstrap_extend,
+ .get_nr_blocks = sm_bootstrap_get_nr_blocks,
+ .get_nr_free = sm_bootstrap_get_nr_free,
+ .get_count = sm_bootstrap_get_count,
+ .count_is_more_than_one = sm_bootstrap_count_is_more_than_one,
+ .set_count = sm_bootstrap_set_count,
+ .inc_block = sm_bootstrap_inc_block,
+ .dec_block = sm_bootstrap_dec_block,
+ .new_block = sm_bootstrap_new_block,
+ .commit = sm_bootstrap_commit,
+ .root_size = sm_bootstrap_root_size,
+ .copy_root = sm_bootstrap_copy_root
+};
+
+/*----------------------------------------------------------------*/
+
+struct dm_space_map *dm_sm_metadata_init(void)
+{
+ struct sm_metadata *smm;
+
+ smm = kmalloc(sizeof(*smm), GFP_KERNEL);
+ if (!smm)
+ return ERR_PTR(-ENOMEM);
+
+ memcpy(&smm->sm, &ops_, sizeof(smm->sm));
+ return &smm->sm;
+}
+
+int dm_sm_metadata_create(struct dm_space_map *sm,
+ struct dm_transaction_manager *tm,
+ dm_block_t nr_blocks,
+ dm_block_t superblock)
+{
+ int r;
+ dm_block_t i;
+ struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
+
+ smm->begin = superblock + 1;
+ smm->recursion_count = 0;
+ smm->allocated_this_transaction = 0;
+ smm->nr_uncommitted = 0;
+
+ memcpy(&smm->sm, &bootstrap_ops_, sizeof(smm->sm));
+ r = metadata_ll_new(&smm->ll, tm, nr_blocks);
+ if (r)
+ return r;
+ memcpy(&smm->sm, &ops_, sizeof(smm->sm));
+
+ /*
+ * Now we need to update the newly created data structures with the
+ * allocated blocks that they were built from.
+ */
+ for (i = superblock; !r && i < smm->begin; i++)
+ r = metadata_ll_inc(&smm->ll, i);
+
+ if (r)
+ return r;
+
+ return sm_metadata_commit(sm);
+}
+
+int dm_sm_metadata_open(struct dm_space_map *sm,
+ struct dm_transaction_manager *tm,
+ void *root, size_t len)
+{
+ int r;
+ struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
+
+ r = metadata_ll_open(&smm->ll, tm, root, len);
+ if (r)
+ return r;
+
+ smm->begin = 0;
+ smm->recursion_count = 0;
+ smm->allocated_this_transaction = 0;
+ smm->nr_uncommitted = 0;
+
+ return sm_metadata_commit(sm);
+}
--- /dev/null
+/*
+ * Copyright (C) 2011 Red Hat, Inc. All rights reserved.
+ *
+ * This file is released under the GPL.
+ */
+
+#ifndef DM_SPACE_MAP_METADATA_H
+#define DM_SPACE_MAP_METADATA_H
+
+#include "dm-transaction-manager.h"
+
+/*
+ * Unfortunately we have to use two-phase construction due to the cycle
+ * between the tm and sm.
+ */
+struct dm_space_map *dm_sm_metadata_init(void);
+
+/*
+ * Create a fresh space map.
+ */
+int dm_sm_metadata_create(struct dm_space_map *sm,
+ struct dm_transaction_manager *tm,
+ dm_block_t nr_blocks,
+ dm_block_t superblock);
+
+/*
+ * Open from a previously-recorded root.
+ */
+int dm_sm_metadata_open(struct dm_space_map *sm,
+ struct dm_transaction_manager *tm,
+ void *root, size_t len);
+
+#endif /* DM_SPACE_MAP_METADATA_H */
--- /dev/null
+/*
+ * Copyright (C) 2011 Red Hat, Inc. All rights reserved.
+ *
+ * This file is released under the GPL.
+ */
+
+#ifndef _LINUX_DM_SPACE_MAP_H
+#define _LINUX_DM_SPACE_MAP_H
+
+#include "dm-block-manager.h"
+
+/*
+ * struct dm_space_map keeps a record of how many times each block in a device
+ * is referenced. It needs to be fixed on disk as part of the transaction.
+ */
+struct dm_space_map {
+ void (*destroy)(struct dm_space_map *sm);
+
+ int (*extend)(struct dm_space_map *sm, dm_block_t extra_blocks);
+
+ int (*get_nr_blocks)(struct dm_space_map *sm, dm_block_t *count);
+ int (*get_nr_free)(struct dm_space_map *sm, dm_block_t *count);
+
+ int (*get_count)(struct dm_space_map *sm, dm_block_t b, uint32_t *result);
+ int (*count_is_more_than_one)(struct dm_space_map *sm, dm_block_t b,
+ int *result);
+ int (*set_count)(struct dm_space_map *sm, dm_block_t b, uint32_t count);
+
+ int (*commit)(struct dm_space_map *sm);
+
+ int (*inc_block)(struct dm_space_map *sm, dm_block_t b);
+ int (*dec_block)(struct dm_space_map *sm, dm_block_t b);
+
+ /*
+ * new_block will increment the returned block.
+ */
+ int (*new_block)(struct dm_space_map *sm, dm_block_t *b);
+
+ /*
+ * The root contains all the information needed to fix the space map.
+ * Generally this info is small, so squirrel it away in a disk block
+ * along with other info.
+ */
+ int (*root_size)(struct dm_space_map *sm, size_t *result);
+ int (*copy_root)(struct dm_space_map *sm, void *copy_to_here, size_t len);
+};
+
+/*----------------------------------------------------------------*/
+
+static inline void dm_sm_destroy(struct dm_space_map *sm)
+{
+ sm->destroy(sm);
+}
+
+static inline int dm_sm_extend(struct dm_space_map *sm, dm_block_t extra_blocks)
+{
+ return sm->extend(sm, extra_blocks);
+}
+
+static inline int dm_sm_get_nr_blocks(struct dm_space_map *sm, dm_block_t *count)
+{
+ return sm->get_nr_blocks(sm, count);
+}
+
+static inline int dm_sm_get_nr_free(struct dm_space_map *sm, dm_block_t *count)
+{
+ return sm->get_nr_free(sm, count);
+}
+
+static inline int dm_sm_get_count(struct dm_space_map *sm, dm_block_t b,
+ uint32_t *result)
+{
+ return sm->get_count(sm, b, result);
+}
+
+static inline int dm_sm_count_is_more_than_one(struct dm_space_map *sm,
+ dm_block_t b, int *result)
+{
+ return sm->count_is_more_than_one(sm, b, result);
+}
+
+static inline int dm_sm_set_count(struct dm_space_map *sm, dm_block_t b,
+ uint32_t count)
+{
+ return sm->set_count(sm, b, count);
+}
+
+static inline int dm_sm_commit(struct dm_space_map *sm)
+{
+ return sm->commit(sm);
+}
+
+static inline int dm_sm_inc_block(struct dm_space_map *sm, dm_block_t b)
+{
+ return sm->inc_block(sm, b);
+}
+
+static inline int dm_sm_dec_block(struct dm_space_map *sm, dm_block_t b)
+{
+ return sm->dec_block(sm, b);
+}
+
+static inline int dm_sm_new_block(struct dm_space_map *sm, dm_block_t *b)
+{
+ return sm->new_block(sm, b);
+}
+
+static inline int dm_sm_root_size(struct dm_space_map *sm, size_t *result)
+{
+ return sm->root_size(sm, result);
+}
+
+static inline int dm_sm_copy_root(struct dm_space_map *sm,
+ void *copy_to_here, size_t len)
+{
+ return sm->copy_root(sm, copy_to_here, len);
+}
+
+#endif /* _LINUX_DM_SPACE_MAP_H */
--- /dev/null
+/*
+ * Copyright (C) 2011 Red Hat, Inc. All rights reserved.
+ *
+ * This file is released under the GPL.
+ */
+#include "dm-transaction-manager.h"
+#include "dm-space-map.h"
+#include "dm-space-map-disk.h"
+#include "dm-space-map-metadata.h"
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/device-mapper.h>
+
+#define DM_MSG_PREFIX "transaction manager"
+
+/*----------------------------------------------------------------*/
+
+struct shadow_info {
+ struct hlist_node hlist;
+ dm_block_t where;
+};
+
+/* it would be nice if we scaled with the size of transaction */
+#define HASH_SIZE 256
+#define HASH_MASK (HASH_SIZE - 1)
+struct dm_transaction_manager {
+ int is_clone;
+ struct dm_transaction_manager *real;
+
+ struct dm_block_manager *bm;
+ struct dm_space_map *sm;
+
+ struct hlist_head buckets[HASH_SIZE];
+
+ /* stats */
+ unsigned shadow_count;
+};
+
+/*----------------------------------------------------------------*/
+
+/* FIXME: similar code in block-manager */
+static unsigned hash_block(dm_block_t b)
+{
+ const unsigned BIG_PRIME = 4294967291UL;
+ return (((unsigned) b) * BIG_PRIME) & HASH_MASK;
+}
+
+static int is_shadow(struct dm_transaction_manager *tm, dm_block_t b)
+{
+ unsigned bucket = hash_block(b);
+ struct shadow_info *si;
+ struct hlist_node *n;
+
+ hlist_for_each_entry(si, n, tm->buckets + bucket, hlist)
+ if (si->where == b)
+ return 1;
+
+ return 0;
+}
+
+/*
+ * This can silently fail if there's no memory. We're ok with this since
+ * creating redundant shadows causes no harm.
+ */
+static void insert_shadow(struct dm_transaction_manager *tm, dm_block_t b)
+{
+ unsigned bucket;
+ struct shadow_info *si;
+
+ si = kmalloc(sizeof(*si), GFP_NOIO);
+ if (si) {
+ si->where = b;
+ bucket = hash_block(b);
+ hlist_add_head(&si->hlist, tm->buckets + bucket);
+ }
+}
+
+static void wipe_shadow_table(struct dm_transaction_manager *tm)
+{
+ int i;
+ for (i = 0; i < HASH_SIZE; i++) {
+ struct shadow_info *si;
+ struct hlist_node *n, *tmp;
+ struct hlist_head *bucket = tm->buckets + i;
+ hlist_for_each_entry_safe(si, n, tmp, bucket, hlist)
+ kfree(si);
+
+ INIT_HLIST_HEAD(bucket);
+ }
+
+ tm->shadow_count = 0;
+}
+
+/*----------------------------------------------------------------*/
+
+static struct dm_transaction_manager *dm_tm_create(struct dm_block_manager *bm,
+ struct dm_space_map *sm)
+{
+ int i;
+ struct dm_transaction_manager *tm;
+
+ tm = kmalloc(sizeof(*tm), GFP_KERNEL);
+ if (!tm)
+ return ERR_PTR(-ENOMEM);
+
+ tm->is_clone = 0;
+ tm->real = NULL;
+ tm->bm = bm;
+ tm->sm = sm;
+
+ for (i = 0; i < HASH_SIZE; i++)
+ INIT_HLIST_HEAD(tm->buckets + i);
+
+ tm->shadow_count = 0;
+
+ return tm;
+}
+
+struct dm_transaction_manager *
+dm_tm_create_non_blocking_clone(struct dm_transaction_manager *real)
+{
+ struct dm_transaction_manager *tm;
+
+ tm = kmalloc(sizeof(*tm), GFP_KERNEL);
+ if (tm) {
+ tm->is_clone = 1;
+ tm->real = real;
+ }
+
+ return tm;
+}
+EXPORT_SYMBOL_GPL(dm_tm_create_non_blocking_clone);
+
+void dm_tm_destroy(struct dm_transaction_manager *tm)
+{
+ kfree(tm);
+}
+EXPORT_SYMBOL_GPL(dm_tm_destroy);
+
+int dm_tm_pre_commit(struct dm_transaction_manager *tm)
+{
+ int r;
+
+ if (tm->is_clone)
+ return -EWOULDBLOCK;
+
+ r = dm_sm_commit(tm->sm);
+ if (r < 0)
+ return r;
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(dm_tm_pre_commit);
+
+int dm_tm_commit(struct dm_transaction_manager *tm, struct dm_block *root)
+{
+ if (tm->is_clone)
+ return -EWOULDBLOCK;
+
+ wipe_shadow_table(tm);
+ return dm_bm_flush_and_unlock(tm->bm, root);
+}
+EXPORT_SYMBOL_GPL(dm_tm_commit);
+
+int dm_tm_new_block(struct dm_transaction_manager *tm,
+ struct dm_block_validator *v,
+ struct dm_block **result)
+{
+ int r;
+ dm_block_t new_block;
+
+ if (tm->is_clone)
+ return -EWOULDBLOCK;
+
+ r = dm_sm_new_block(tm->sm, &new_block);
+ if (r < 0)
+ return r;
+
+ r = dm_bm_write_lock_zero(tm->bm, new_block, v, result);
+ if (r < 0) {
+ dm_sm_dec_block(tm->sm, new_block);
+ return r;
+ }
+
+ /*
+ * New blocks count as shadows, in that they don't need to be
+ * shadowed again.
+ */
+ insert_shadow(tm, new_block);
+
+ return 0;
+}
+
+static int __shadow_block(struct dm_transaction_manager *tm, dm_block_t orig,
+ struct dm_block_validator *v,
+ struct dm_block **result, int *inc_children)
+{
+ int r;
+ dm_block_t new;
+ uint32_t count;
+ struct dm_block *orig_block;
+
+ r = dm_sm_new_block(tm->sm, &new);
+ if (r < 0)
+ return r;
+
+ r = dm_bm_write_lock_zero(tm->bm, new, v, result);
+ if (r < 0) {
+ dm_sm_dec_block(tm->sm, new);
+ return r;
+ }
+
+ r = dm_bm_read_lock(tm->bm, orig, v, &orig_block);
+ if (r < 0) {
+ dm_sm_dec_block(tm->sm, new);
+ return r;
+ }
+ memcpy(dm_block_data(*result), dm_block_data(orig_block),
+ dm_bm_block_size(tm->bm));
+ r = dm_bm_unlock(orig_block);
+ if (r < 0) {
+ dm_sm_dec_block(tm->sm, new);
+ return r;
+ }
+
+ r = dm_sm_get_count(tm->sm, orig, &count);
+ if (r < 0) {
+ dm_sm_dec_block(tm->sm, new);
+ dm_bm_unlock(*result);
+ return r;
+ }
+
+ r = dm_sm_dec_block(tm->sm, orig);
+ if (r < 0) {
+ dm_sm_dec_block(tm->sm, new);
+ dm_bm_unlock(*result);
+ return r;
+ }
+
+ *inc_children = count > 1;
+ return 0;
+}
+
+int dm_tm_shadow_block(struct dm_transaction_manager *tm, dm_block_t orig,
+ struct dm_block_validator *v, struct dm_block **result,
+ int *inc_children)
+{
+ int r, more_than_one;
+
+ if (tm->is_clone)
+ return -EWOULDBLOCK;
+
+ if (is_shadow(tm, orig)) {
+ r = dm_sm_count_is_more_than_one(tm->sm, orig, &more_than_one);
+ if (r < 0)
+ return r;
+
+ if (!more_than_one) {
+ *inc_children = 0;
+ return dm_bm_write_lock(tm->bm, orig, v, result);
+ }
+ /* fall through */
+ }
+
+ r = __shadow_block(tm, orig, v, result, inc_children);
+ if (r < 0)
+ return r;
+ tm->shadow_count++;
+ insert_shadow(tm, dm_block_location(*result));
+
+ return r;
+}
+
+int dm_tm_read_lock(struct dm_transaction_manager *tm, dm_block_t b,
+ struct dm_block_validator *v,
+ struct dm_block **blk)
+{
+ if (tm->is_clone)
+ return dm_bm_read_try_lock(tm->real->bm, b, v, blk);
+
+ return dm_bm_read_lock(tm->bm, b, v, blk);
+}
+
+int dm_tm_unlock(struct dm_transaction_manager *tm, struct dm_block *b)
+{
+ return dm_bm_unlock(b);
+}
+EXPORT_SYMBOL_GPL(dm_tm_unlock);
+
+void dm_tm_inc(struct dm_transaction_manager *tm, dm_block_t b)
+{
+ BUG_ON(tm->is_clone);
+ dm_sm_inc_block(tm->sm, b);
+}
+EXPORT_SYMBOL_GPL(dm_tm_inc);
+
+void dm_tm_dec(struct dm_transaction_manager *tm, dm_block_t b)
+{
+ BUG_ON(tm->is_clone);
+ dm_sm_dec_block(tm->sm, b);
+}
+
+int dm_tm_ref(struct dm_transaction_manager *tm, dm_block_t b,
+ uint32_t *result)
+{
+ if (tm->is_clone)
+ return -EWOULDBLOCK;
+
+ return dm_sm_get_count(tm->sm, b, result);
+}
+
+struct dm_block_manager *dm_tm_get_bm(struct dm_transaction_manager *tm)
+{
+ BUG_ON(tm->is_clone);
+ return tm->bm;
+}
+
+/*----------------------------------------------------------------*/
+
+static int dm_tm_create_internal(struct dm_block_manager *bm,
+ dm_block_t sb_location,
+ struct dm_block_validator *sb_validator,
+ size_t root_offset, size_t root_max_len,
+ struct dm_transaction_manager **tm,
+ struct dm_space_map **sm,
+ struct dm_block **sblock,
+ int create)
+{
+ int r;
+
+ *sm = dm_sm_metadata_init();
+ if (IS_ERR(*sm))
+ return PTR_ERR(*sm);
+
+ *tm = dm_tm_create(bm, *sm);
+ if (IS_ERR(*tm)) {
+ dm_sm_destroy(*sm);
+ return -1;
+ }
+
+ if (create) {
+ r = dm_bm_write_lock_zero(dm_tm_get_bm(*tm), sb_location,
+ sb_validator, sblock);
+ if (r < 0) {
+ DMERR("couldn't lock superblock");
+ goto bad1;
+ }
+
+ r = dm_sm_metadata_create(*sm, *tm, dm_bm_nr_blocks(bm),
+ sb_location);
+ if (r) {
+ DMERR("couldn't create metadata space map");
+ goto bad2;
+ }
+
+ } else {
+ r = dm_bm_write_lock(dm_tm_get_bm(*tm), sb_location,
+ sb_validator, sblock);
+ if (r < 0) {
+ DMERR("couldn't lock superblock");
+ goto bad1;
+ }
+
+ r = dm_sm_metadata_open(*sm, *tm,
+ dm_block_data(*sblock) + root_offset,
+ root_max_len);
+ if (IS_ERR(*sm)) {
+ DMERR("couldn't open metadata space map");
+ goto bad2;
+ }
+ }
+
+ return 0;
+
+bad2:
+ dm_tm_unlock(*tm, *sblock);
+bad1:
+ dm_tm_destroy(*tm);
+ dm_sm_destroy(*sm);
+ return r;
+}
+
+int dm_tm_create_with_sm(struct dm_block_manager *bm, dm_block_t sb_location,
+ struct dm_block_validator *sb_validator,
+ struct dm_transaction_manager **tm,
+ struct dm_space_map **sm, struct dm_block **sblock)
+{
+ return dm_tm_create_internal(bm, sb_location, sb_validator,
+ 0, 0, tm, sm, sblock, 1);
+}
+EXPORT_SYMBOL_GPL(dm_tm_create_with_sm);
+
+int dm_tm_open_with_sm(struct dm_block_manager *bm, dm_block_t sb_location,
+ struct dm_block_validator *sb_validator,
+ size_t root_offset, size_t root_max_len,
+ struct dm_transaction_manager **tm,
+ struct dm_space_map **sm, struct dm_block **sblock)
+{
+ return dm_tm_create_internal(bm, sb_location, sb_validator, root_offset,
+ root_max_len, tm, sm, sblock, 0);
+}
+EXPORT_SYMBOL_GPL(dm_tm_open_with_sm);
+
+/*----------------------------------------------------------------*/
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Joe Thornber");
+MODULE_DESCRIPTION("Immutable metadata library for dm");
+
+/*----------------------------------------------------------------*/
--- /dev/null
+/*
+ * Copyright (C) 2011 Red Hat, Inc. All rights reserved.
+ *
+ * This file is released under the GPL.
+ */
+
+#ifndef _LINUX_DM_TRANSACTION_MANAGER_H
+#define _LINUX_DM_TRANSACTION_MANAGER_H
+
+#include "dm-block-manager.h"
+
+struct dm_transaction_manager;
+struct dm_space_map;
+
+/*----------------------------------------------------------------*/
+
+/*
+ * This manages the scope of a transaction. It also enforces immutability
+ * of the on-disk data structures by limiting access to writeable blocks.
+ *
+ * Clients should not fiddle with the block manager directly.
+ */
+
+void dm_tm_destroy(struct dm_transaction_manager *tm);
+
+/*
+ * The non-blocking version of a transaction manager is intended for use in
+ * fast path code that needs to do lookups e.g. a dm mapping function.
+ * You create the non-blocking variant from a normal tm. The interface is
+ * the same, except that most functions will just return -EWOULDBLOCK.
+ * Call dm_tm_destroy() as you would with a normal tm when you've finished
+ * with it. You may not destroy the original prior to clones.
+ */
+struct dm_transaction_manager *dm_tm_create_non_blocking_clone(struct dm_transaction_manager *real);
+
+/*
+ * We use a 2-phase commit here.
+ *
+ * i) In the first phase the block manager is told to start flushing, and
+ * the changes to the space map are written to disk. You should interrogate
+ * your particular space map to get detail of its root node etc. to be
+ * included in your superblock.
+ *
+ * ii) @root will be committed last. You shouldn't use more than the
+ * first 512 bytes of @root if you wish the transaction to survive a power
+ * failure. You *must* have a write lock held on @root for both stage (i)
+ * and (ii). The commit will drop the write lock.
+ */
+int dm_tm_pre_commit(struct dm_transaction_manager *tm);
+int dm_tm_commit(struct dm_transaction_manager *tm, struct dm_block *root);
+
+/*
+ * These methods are the only way to get hold of a writeable block.
+ */
+
+
+/*
+ * dm_tm_new_block() is pretty self-explanatory. Make sure you do actually
+ * write to the whole of @data before you unlock, otherwise you could get
+ * a data leak. (The other option is for tm_new_block() to zero new blocks
+ * before handing them out, which will be redundant in most, if not all,
+ * cases).
+ * Zeroes the new block and returns with write lock held.
+ */
+int dm_tm_new_block(struct dm_transaction_manager *tm,
+ struct dm_block_validator *v,
+ struct dm_block **result);
+
+/*
+ * dm_tm_shadow_block() allocates a new block and copies the data from @orig
+ * to it. It then decrements the reference count on original block. Use
+ * this to update the contents of a block in a data structure, don't
+ * confuse this with a clone - you shouldn't access the orig block after
+ * this operation. Because the tm knows the scope of the transaction it
+ * can optimise requests for a shadow of a shadow to a no-op. Don't forget
+ * to unlock when you've finished with the shadow.
+ *
+ * The @inc_children flag is used to tell the caller whether it needs to
+ * adjust reference counts for children. (Data in the block may refer to
+ * other blocks.)
+ *
+ * Shadowing implicitly drops a reference on @orig so you must not have
+ * it locked when you call this.
+ */
+int dm_tm_shadow_block(struct dm_transaction_manager *tm, dm_block_t orig,
+ struct dm_block_validator *v,
+ struct dm_block **result, int *inc_children);
+
+/*
+ * Read access. You can lock any block you want. If there's a write lock
+ * on it outstanding then it'll block.
+ */
+int dm_tm_read_lock(struct dm_transaction_manager *tm, dm_block_t b,
+ struct dm_block_validator *v,
+ struct dm_block **result);
+
+int dm_tm_unlock(struct dm_transaction_manager *tm, struct dm_block *b);
+
+/*
+ * Functions for altering the reference count of a block directly.
+ */
+void dm_tm_inc(struct dm_transaction_manager *tm, dm_block_t b);
+
+void dm_tm_dec(struct dm_transaction_manager *tm, dm_block_t b);
+
+int dm_tm_ref(struct dm_transaction_manager *tm, dm_block_t b,
+ uint32_t *result);
+
+struct dm_block_manager *dm_tm_get_bm(struct dm_transaction_manager *tm);
+
+/*
+ * A little utility that ties the knot by producing a transaction manager
+ * that has a space map managed by the transaction manager...
+ *
+ * Returns a tm that has an open transaction to write the new disk sm.
+ * Caller should store the new sm root and commit.
+ */
+int dm_tm_create_with_sm(struct dm_block_manager *bm, dm_block_t sb_location,
+ struct dm_block_validator *sb_validator,
+ struct dm_transaction_manager **tm,
+ struct dm_space_map **sm, struct dm_block **sblock);
+
+int dm_tm_open_with_sm(struct dm_block_manager *bm, dm_block_t sb_location,
+ struct dm_block_validator *sb_validator,
+ size_t root_offset, size_t root_max_len,
+ struct dm_transaction_manager **tm,
+ struct dm_space_map **sm, struct dm_block **sblock);
+
+/*----------------------------------------------------------------*/
+
+#endif /* _LINUX_DM_TRANSACTION_MANAGER_H */
projects / karo-tx-linux.git / commitdiff