Imported Upstream version 4.6.1

1 files changed, 893 insertions, 0 deletions

diff --git a/extent_io.c b/extent_io.c
new file mode 100644
index 00000000..c99d3627
--- /dev/null
+++ b/extent_io.c
@@ -0,0 +1,893 @@
+
+/*
+ * Copyright (C) 2007 Oracle.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include "kerncompat.h"
+#include "extent_io.h"
+#include "list.h"
+#include "ctree.h"
+#include "volumes.h"
+#include "internal.h"
+
+void extent_io_tree_init(struct extent_io_tree *tree)
+{
+	cache_tree_init(&tree->state);
+	cache_tree_init(&tree->cache);
+	INIT_LIST_HEAD(&tree->lru);
+	tree->cache_size = 0;
+}
+
+static struct extent_state *alloc_extent_state(void)
+{
+	struct extent_state *state;
+
+	state = malloc(sizeof(*state));
+	if (!state)
+		return NULL;
+	state->cache_node.objectid = 0;
+	state->refs = 1;
+	state->state = 0;
+	state->xprivate = 0;
+	return state;
+}
+
+static void btrfs_free_extent_state(struct extent_state *state)
+{
+	state->refs--;
+	BUG_ON(state->refs < 0);
+	if (state->refs == 0)
+		free(state);
+}
+
+static void free_extent_state_func(struct cache_extent *cache)
+{
+	struct extent_state *es;
+
+	es = container_of(cache, struct extent_state, cache_node);
+	btrfs_free_extent_state(es);
+}
+
+void extent_io_tree_cleanup(struct extent_io_tree *tree)
+{
+	struct extent_buffer *eb;
+
+	while(!list_empty(&tree->lru)) {
+		eb = list_entry(tree->lru.next, struct extent_buffer, lru);
+		fprintf(stderr, "extent buffer leak: "
+			"start %llu len %u\n",
+			(unsigned long long)eb->start, eb->len);
+		free_extent_buffer(eb);
+	}
+
+	cache_tree_free_extents(&tree->state, free_extent_state_func);
+}
+
+static inline void update_extent_state(struct extent_state *state)
+{
+	state->cache_node.start = state->start;
+	state->cache_node.size = state->end + 1 - state->start;
+}
+
+/*
+ * Utility function to look for merge candidates inside a given range.
+ * Any extents with matching state are merged together into a single
+ * extent in the tree. Extents with EXTENT_IO in their state field are
+ * not merged
+ */
+static int merge_state(struct extent_io_tree *tree,
+		       struct extent_state *state)
+{
+	struct extent_state *other;
+	struct cache_extent *other_node;
+
+	if (state->state & EXTENT_IOBITS)
+		return 0;
+
+	other_node = prev_cache_extent(&state->cache_node);
+	if (other_node) {
+		other = container_of(other_node, struct extent_state,
+				     cache_node);
+		if (other->end == state->start - 1 &&
+		    other->state == state->state) {
+			state->start = other->start;
+			update_extent_state(state);
+			remove_cache_extent(&tree->state, &other->cache_node);
+			btrfs_free_extent_state(other);
+		}
+	}
+	other_node = next_cache_extent(&state->cache_node);
+	if (other_node) {
+		other = container_of(other_node, struct extent_state,
+				     cache_node);
+		if (other->start == state->end + 1 &&
+		    other->state == state->state) {
+			other->start = state->start;
+			update_extent_state(other);
+			remove_cache_extent(&tree->state, &state->cache_node);
+			btrfs_free_extent_state(state);
+		}
+	}
+	return 0;
+}
+
+/*
+ * insert an extent_state struct into the tree.  'bits' are set on the
+ * struct before it is inserted.
+ */
+static int insert_state(struct extent_io_tree *tree,
+			struct extent_state *state, u64 start, u64 end,
+			int bits)
+{
+	int ret;
+
+	BUG_ON(end < start);
+	state->state |= bits;
+	state->start = start;
+	state->end = end;
+	update_extent_state(state);
+	ret = insert_cache_extent(&tree->state, &state->cache_node);
+	BUG_ON(ret);
+	merge_state(tree, state);
+	return 0;
+}
+
+/*
+ * split a given extent state struct in two, inserting the preallocated
+ * struct 'prealloc' as the newly created second half.  'split' indicates an
+ * offset inside 'orig' where it should be split.
+ */
+static int split_state(struct extent_io_tree *tree, struct extent_state *orig,
+		       struct extent_state *prealloc, u64 split)
+{
+	int ret;
+	prealloc->start = orig->start;
+	prealloc->end = split - 1;
+	prealloc->state = orig->state;
+	update_extent_state(prealloc);
+	orig->start = split;
+	update_extent_state(orig);
+	ret = insert_cache_extent(&tree->state, &prealloc->cache_node);
+	BUG_ON(ret);
+	return 0;
+}
+
+/*
+ * clear some bits on a range in the tree.
+ */
+static int clear_state_bit(struct extent_io_tree *tree,
+			    struct extent_state *state, int bits)
+{
+	int ret = state->state & bits;
+
+	state->state &= ~bits;
+	if (state->state == 0) {
+		remove_cache_extent(&tree->state, &state->cache_node);
+		btrfs_free_extent_state(state);
+	} else {
+		merge_state(tree, state);
+	}
+	return ret;
+}
+
+/*
+ * clear some bits on a range in the tree.
+ */
+int clear_extent_bits(struct extent_io_tree *tree, u64 start,
+		      u64 end, int bits, gfp_t mask)
+{
+	struct extent_state *state;
+	struct extent_state *prealloc = NULL;
+	struct cache_extent *node;
+	u64 last_end;
+	int err;
+	int set = 0;
+
+again:
+	if (!prealloc) {
+		prealloc = alloc_extent_state();
+		if (!prealloc)
+			return -ENOMEM;
+	}
+
+	/*
+	 * this search will find the extents that end after
+	 * our range starts
+	 */
+	node = search_cache_extent(&tree->state, start);
+	if (!node)
+		goto out;
+	state = container_of(node, struct extent_state, cache_node);
+	if (state->start > end)
+		goto out;
+	last_end = state->end;
+
+	/*
+	 *     | ---- desired range ---- |
+	 *  | state | or
+	 *  | ------------- state -------------- |
+	 *
+	 * We need to split the extent we found, and may flip
+	 * bits on second half.
+	 *
+	 * If the extent we found extends past our range, we
+	 * just split and search again.  It'll get split again
+	 * the next time though.
+	 *
+	 * If the extent we found is inside our range, we clear
+	 * the desired bit on it.
+	 */
+	if (state->start < start) {
+		err = split_state(tree, state, prealloc, start);
+		BUG_ON(err == -EEXIST);
+		prealloc = NULL;
+		if (err)
+			goto out;
+		if (state->end <= end) {
+			set |= clear_state_bit(tree, state, bits);
+			if (last_end == (u64)-1)
+				goto out;
+			start = last_end + 1;
+		} else {
+			start = state->start;
+		}
+		goto search_again;
+	}
+	/*
+	 * | ---- desired range ---- |
+	 *                        | state |
+	 * We need to split the extent, and clear the bit
+	 * on the first half
+	 */
+	if (state->start <= end && state->end > end) {
+		err = split_state(tree, state, prealloc, end + 1);
+		BUG_ON(err == -EEXIST);
+
+		set |= clear_state_bit(tree, prealloc, bits);
+		prealloc = NULL;
+		goto out;
+	}
+
+	start = state->end + 1;
+	set |= clear_state_bit(tree, state, bits);
+	if (last_end == (u64)-1)
+		goto out;
+	start = last_end + 1;
+	goto search_again;
+out:
+	if (prealloc)
+		btrfs_free_extent_state(prealloc);
+	return set;
+
+search_again:
+	if (start > end)
+		goto out;
+	goto again;
+}
+
+/*
+ * set some bits on a range in the tree.
+ */
+int set_extent_bits(struct extent_io_tree *tree, u64 start,
+		    u64 end, int bits, gfp_t mask)
+{
+	struct extent_state *state;
+	struct extent_state *prealloc = NULL;
+	struct cache_extent *node;
+	int err = 0;
+	u64 last_start;
+	u64 last_end;
+again:
+	if (!prealloc) {
+		prealloc = alloc_extent_state();
+		if (!prealloc)
+			return -ENOMEM;
+	}
+
+	/*
+	 * this search will find the extents that end after
+	 * our range starts
+	 */
+	node = search_cache_extent(&tree->state, start);
+	if (!node) {
+		err = insert_state(tree, prealloc, start, end, bits);
+		BUG_ON(err == -EEXIST);
+		prealloc = NULL;
+		goto out;
+	}
+
+	state = container_of(node, struct extent_state, cache_node);
+	last_start = state->start;
+	last_end = state->end;
+
+	/*
+	 * | ---- desired range ---- |
+	 * | state |
+	 *
+	 * Just lock what we found and keep going
+	 */
+	if (state->start == start && state->end <= end) {
+		state->state |= bits;
+		merge_state(tree, state);
+		if (last_end == (u64)-1)
+			goto out;
+		start = last_end + 1;
+		goto search_again;
+	}
+	/*
+	 *     | ---- desired range ---- |
+	 * | state |
+	 *   or
+	 * | ------------- state -------------- |
+	 *
+	 * We need to split the extent we found, and may flip bits on
+	 * second half.
+	 *
+	 * If the extent we found extends past our
+	 * range, we just split and search again.  It'll get split
+	 * again the next time though.
+	 *
+	 * If the extent we found is inside our range, we set the
+	 * desired bit on it.
+	 */
+	if (state->start < start) {
+		err = split_state(tree, state, prealloc, start);
+		BUG_ON(err == -EEXIST);
+		prealloc = NULL;
+		if (err)
+			goto out;
+		if (state->end <= end) {
+			state->state |= bits;
+			start = state->end + 1;
+			merge_state(tree, state);
+			if (last_end == (u64)-1)
+				goto out;
+			start = last_end + 1;
+		} else {
+			start = state->start;
+		}
+		goto search_again;
+	}
+	/*
+	 * | ---- desired range ---- |
+	 *     | state | or               | state |
+	 *
+	 * There's a hole, we need to insert something in it and
+	 * ignore the extent we found.
+	 */
+	if (state->start > start) {
+		u64 this_end;
+		if (end < last_start)
+			this_end = end;
+		else
+			this_end = last_start -1;
+		err = insert_state(tree, prealloc, start, this_end,
+				bits);
+		BUG_ON(err == -EEXIST);
+		prealloc = NULL;
+		if (err)
+			goto out;
+		start = this_end + 1;
+		goto search_again;
+	}
+	/*
+	 * | ---- desired range ---- |
+	 * | ---------- state ---------- |
+	 * We need to split the extent, and set the bit
+	 * on the first half
+	 */
+	err = split_state(tree, state, prealloc, end + 1);
+	BUG_ON(err == -EEXIST);
+
+	state->state |= bits;
+	merge_state(tree, prealloc);
+	prealloc = NULL;
+out:
+	if (prealloc)
+		btrfs_free_extent_state(prealloc);
+	return err;
+search_again:
+	if (start > end)
+		goto out;
+	goto again;
+}
+
+int set_extent_dirty(struct extent_io_tree *tree, u64 start, u64 end,
+		     gfp_t mask)
+{
+	return set_extent_bits(tree, start, end, EXTENT_DIRTY, mask);
+}
+
+int clear_extent_dirty(struct extent_io_tree *tree, u64 start, u64 end,
+		       gfp_t mask)
+{
+	return clear_extent_bits(tree, start, end, EXTENT_DIRTY, mask);
+}
+
+int find_first_extent_bit(struct extent_io_tree *tree, u64 start,
+			  u64 *start_ret, u64 *end_ret, int bits)
+{
+	struct cache_extent *node;
+	struct extent_state *state;
+	int ret = 1;
+
+	/*
+	 * this search will find all the extents that end after
+	 * our range starts.
+	 */
+	node = search_cache_extent(&tree->state, start);
+	if (!node)
+		goto out;
+
+	while(1) {
+		state = container_of(node, struct extent_state, cache_node);
+		if (state->end >= start && (state->state & bits)) {
+			*start_ret = state->start;
+			*end_ret = state->end;
+			ret = 0;
+			break;
+		}
+		node = next_cache_extent(node);
+		if (!node)
+			break;
+	}
+out:
+	return ret;
+}
+
+int test_range_bit(struct extent_io_tree *tree, u64 start, u64 end,
+		   int bits, int filled)
+{
+	struct extent_state *state = NULL;
+	struct cache_extent *node;
+	int bitset = 0;
+
+	node = search_cache_extent(&tree->state, start);
+	while (node && start <= end) {
+		state = container_of(node, struct extent_state, cache_node);
+
+		if (filled && state->start > start) {
+			bitset = 0;
+			break;
+		}
+		if (state->start > end)
+			break;
+		if (state->state & bits) {
+			bitset = 1;
+			if (!filled)
+				break;
+		} else if (filled) {
+			bitset = 0;
+			break;
+		}
+		start = state->end + 1;
+		if (start > end)
+			break;
+		node = next_cache_extent(node);
+		if (!node) {
+			if (filled)
+				bitset = 0;
+			break;
+		}
+	}
+	return bitset;
+}
+
+int set_state_private(struct extent_io_tree *tree, u64 start, u64 private)
+{
+	struct cache_extent *node;
+	struct extent_state *state;
+	int ret = 0;
+
+	node = search_cache_extent(&tree->state, start);
+	if (!node) {
+		ret = -ENOENT;
+		goto out;
+	}
+	state = container_of(node, struct extent_state, cache_node);
+	if (state->start != start) {
+		ret = -ENOENT;
+		goto out;
+	}
+	state->xprivate = private;
+out:
+	return ret;
+}
+
+int get_state_private(struct extent_io_tree *tree, u64 start, u64 *private)
+{
+	struct cache_extent *node;
+	struct extent_state *state;
+	int ret = 0;
+
+	node = search_cache_extent(&tree->state, start);
+	if (!node) {
+		ret = -ENOENT;
+		goto out;
+	}
+	state = container_of(node, struct extent_state, cache_node);
+	if (state->start != start) {
+		ret = -ENOENT;
+		goto out;
+	}
+	*private = state->xprivate;
+out:
+	return ret;
+}
+
+static struct extent_buffer *__alloc_extent_buffer(struct extent_io_tree *tree,
+						   u64 bytenr, u32 blocksize)
+{
+	struct extent_buffer *eb;
+
+	eb = calloc(1, sizeof(struct extent_buffer) + blocksize);
+	if (!eb) {
+		BUG();
+		return NULL;
+	}
+
+	eb->start = bytenr;
+	eb->len = blocksize;
+	eb->refs = 1;
+	eb->flags = 0;
+	eb->tree = tree;
+	eb->fd = -1;
+	eb->dev_bytenr = (u64)-1;
+	eb->cache_node.start = bytenr;
+	eb->cache_node.size = blocksize;
+	INIT_LIST_HEAD(&eb->recow);
+
+	return eb;
+}
+
+struct extent_buffer *btrfs_clone_extent_buffer(struct extent_buffer *src)
+{
+	struct extent_buffer *new;
+
+	new = __alloc_extent_buffer(NULL, src->start, src->len);
+	if (new == NULL)
+		return NULL;
+
+	copy_extent_buffer(new, src, 0, 0, src->len);
+	new->flags |= EXTENT_BUFFER_DUMMY;
+
+	return new;
+}
+
+void free_extent_buffer(struct extent_buffer *eb)
+{
+	if (!eb || IS_ERR(eb))
+		return;
+
+	eb->refs--;
+	BUG_ON(eb->refs < 0);
+	if (eb->refs == 0) {
+		struct extent_io_tree *tree = eb->tree;
+		BUG_ON(eb->flags & EXTENT_DIRTY);
+		list_del_init(&eb->lru);
+		list_del_init(&eb->recow);
+		if (!(eb->flags & EXTENT_BUFFER_DUMMY)) {
+			BUG_ON(tree->cache_size < eb->len);
+			remove_cache_extent(&tree->cache, &eb->cache_node);
+			tree->cache_size -= eb->len;
+		}
+		free(eb);
+	}
+}
+
+struct extent_buffer *find_extent_buffer(struct extent_io_tree *tree,
+					 u64 bytenr, u32 blocksize)
+{
+	struct extent_buffer *eb = NULL;
+	struct cache_extent *cache;
+
+	cache = lookup_cache_extent(&tree->cache, bytenr, blocksize);
+	if (cache && cache->start == bytenr &&
+	    cache->size == blocksize) {
+		eb = container_of(cache, struct extent_buffer, cache_node);
+		list_move_tail(&eb->lru, &tree->lru);
+		eb->refs++;
+	}
+	return eb;
+}
+
+struct extent_buffer *find_first_extent_buffer(struct extent_io_tree *tree,
+					       u64 start)
+{
+	struct extent_buffer *eb = NULL;
+	struct cache_extent *cache;
+
+	cache = search_cache_extent(&tree->cache, start);
+	if (cache) {
+		eb = container_of(cache, struct extent_buffer, cache_node);
+		list_move_tail(&eb->lru, &tree->lru);
+		eb->refs++;
+	}
+	return eb;
+}
+
+struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree,
+					  u64 bytenr, u32 blocksize)
+{
+	struct extent_buffer *eb;
+	struct cache_extent *cache;
+
+	cache = lookup_cache_extent(&tree->cache, bytenr, blocksize);
+	if (cache && cache->start == bytenr &&
+	    cache->size == blocksize) {
+		eb = container_of(cache, struct extent_buffer, cache_node);
+		list_move_tail(&eb->lru, &tree->lru);
+		eb->refs++;
+	} else {
+		int ret;
+
+		if (cache) {
+			eb = container_of(cache, struct extent_buffer,
+					  cache_node);
+			free_extent_buffer(eb);
+		}
+		eb = __alloc_extent_buffer(tree, bytenr, blocksize);
+		if (!eb)
+			return NULL;
+		ret = insert_cache_extent(&tree->cache, &eb->cache_node);
+		if (ret) {
+			free(eb);
+			return NULL;
+		}
+		list_add_tail(&eb->lru, &tree->lru);
+		tree->cache_size += blocksize;
+	}
+	return eb;
+}
+
+int read_extent_from_disk(struct extent_buffer *eb,
+			  unsigned long offset, unsigned long len)
+{
+	int ret;
+	ret = pread(eb->fd, eb->data + offset, len, eb->dev_bytenr);
+	if (ret < 0) {
+		ret = -errno;
+		goto out;
+	}
+	if (ret != len) {
+		ret = -EIO;
+		goto out;
+	}
+	ret = 0;
+out:
+	return ret;
+}
+
+int write_extent_to_disk(struct extent_buffer *eb)
+{
+	int ret;
+	ret = pwrite(eb->fd, eb->data, eb->len, eb->dev_bytenr);
+	if (ret < 0)
+		goto out;
+	if (ret != eb->len) {
+		ret = -EIO;
+		goto out;
+	}
+	ret = 0;
+out:
+	return ret;
+}
+
+int read_data_from_disk(struct btrfs_fs_info *info, void *buf, u64 offset,
+			u64 bytes, int mirror)
+{
+	struct btrfs_multi_bio *multi = NULL;
+	struct btrfs_device *device;
+	u64 bytes_left = bytes;
+	u64 read_len;
+	u64 total_read = 0;
+	int ret;
+
+	while (bytes_left) {
+		read_len = bytes_left;
+		ret = btrfs_map_block(&info->mapping_tree, READ, offset,
+				      &read_len, &multi, mirror, NULL);
+		if (ret) {
+			fprintf(stderr, "Couldn't map the block %Lu\n",
+				offset);
+			return -EIO;
+		}
+		device = multi->stripes[0].dev;
+
+		read_len = min(bytes_left, read_len);
+		if (device->fd <= 0) {
+			kfree(multi);
+			return -EIO;
+		}
+
+		ret = pread(device->fd, buf + total_read, read_len,
+			    multi->stripes[0].physical);
+		kfree(multi);
+		if (ret < 0) {
+			fprintf(stderr, "Error reading %Lu, %d\n", offset,
+				ret);
+			return ret;
+		}
+		if (ret != read_len) {
+			fprintf(stderr, "Short read for %Lu, read %d, "
+				"read_len %Lu\n", offset, ret, read_len);
+			return -EIO;
+		}
+
+		bytes_left -= read_len;
+		offset += read_len;
+		total_read += read_len;
+	}
+
+	return 0;
+}
+
+int write_data_to_disk(struct btrfs_fs_info *info, void *buf, u64 offset,
+		      u64 bytes, int mirror)
+{
+	struct btrfs_multi_bio *multi = NULL;
+	struct btrfs_device *device;
+	u64 bytes_left = bytes;
+	u64 this_len;
+	u64 total_write = 0;
+	u64 *raid_map = NULL;
+	u64 dev_bytenr;
+	int dev_nr;
+	int ret = 0;
+
+	while (bytes_left > 0) {
+		this_len = bytes_left;
+		dev_nr = 0;
+
+		ret = btrfs_map_block(&info->mapping_tree, WRITE, offset,
+				      &this_len, &multi, mirror, &raid_map);
+		if (ret) {
+			fprintf(stderr, "Couldn't map the block %Lu\n",
+				offset);
+			return -EIO;
+		}
+
+		if (raid_map) {
+			struct extent_buffer *eb;
+			u64 stripe_len = this_len;
+
+			this_len = min(this_len, bytes_left);
+			this_len = min(this_len, (u64)info->tree_root->nodesize);
+
+			eb = malloc(sizeof(struct extent_buffer) + this_len);
+			BUG_ON(!eb);
+
+			memset(eb, 0, sizeof(struct extent_buffer) + this_len);
+			eb->start = offset;
+			eb->len = this_len;
+
+			memcpy(eb->data, buf + total_write, this_len);
+			ret = write_raid56_with_parity(info, eb, multi,
+						       stripe_len, raid_map);
+			BUG_ON(ret);
+
+			free(eb);
+			kfree(raid_map);
+			raid_map = NULL;
+		} else while (dev_nr < multi->num_stripes) {
+			device = multi->stripes[dev_nr].dev;
+			if (device->fd <= 0) {
+				kfree(multi);
+				return -EIO;
+			}
+
+			dev_bytenr = multi->stripes[dev_nr].physical;
+			this_len = min(this_len, bytes_left);
+			dev_nr++;
+
+			ret = pwrite(device->fd, buf + total_write, this_len, dev_bytenr);
+			if (ret != this_len) {
+				if (ret < 0) {
+					fprintf(stderr, "Error writing to "
+						"device %d\n", errno);
+					ret = errno;
+					kfree(multi);
+					return ret;
+				} else {
+					fprintf(stderr, "Short write\n");
+					kfree(multi);
+					return -EIO;
+				}
+			}
+		}
+
+		BUG_ON(bytes_left < this_len);
+
+		bytes_left -= this_len;
+		offset += this_len;
+		total_write += this_len;
+
+		kfree(multi);
+		multi = NULL;
+	}
+	return 0;
+}
+
+int set_extent_buffer_dirty(struct extent_buffer *eb)
+{
+	struct extent_io_tree *tree = eb->tree;
+	if (!(eb->flags & EXTENT_DIRTY)) {
+		eb->flags |= EXTENT_DIRTY;
+		set_extent_dirty(tree, eb->start, eb->start + eb->len - 1, 0);
+		extent_buffer_get(eb);
+	}
+	return 0;
+}
+
+int clear_extent_buffer_dirty(struct extent_buffer *eb)
+{
+	struct extent_io_tree *tree = eb->tree;
+	if (eb->flags & EXTENT_DIRTY) {
+		eb->flags &= ~EXTENT_DIRTY;
+		clear_extent_dirty(tree, eb->start, eb->start + eb->len - 1, 0);
+		free_extent_buffer(eb);
+	}
+	return 0;
+}
+
+int memcmp_extent_buffer(struct extent_buffer *eb, const void *ptrv,
+			 unsigned long start, unsigned long len)
+{
+	return memcmp(eb->data + start, ptrv, len);
+}
+
+void read_extent_buffer(struct extent_buffer *eb, void *dst,
+			unsigned long start, unsigned long len)
+{
+	memcpy(dst, eb->data + start, len);
+}
+
+void write_extent_buffer(struct extent_buffer *eb, const void *src,
+			 unsigned long start, unsigned long len)
+{
+	memcpy(eb->data + start, src, len);
+}
+
+void copy_extent_buffer(struct extent_buffer *dst, struct extent_buffer *src,
+			unsigned long dst_offset, unsigned long src_offset,
+			unsigned long len)
+{
+	memcpy(dst->data + dst_offset, src->data + src_offset, len);
+}
+
+void memmove_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
+			   unsigned long src_offset, unsigned long len)
+{
+	memmove(dst->data + dst_offset, dst->data + src_offset, len);
+}
+
+void memset_extent_buffer(struct extent_buffer *eb, char c,
+			  unsigned long start, unsigned long len)
+{
+	memset(eb->data + start, c, len);
+}
+
+int extent_buffer_test_bit(struct extent_buffer *eb, unsigned long start,
+			   unsigned long nr)
+{
+	return test_bit(nr, (unsigned long *)(eb->data + start));
+}