Hello, This patch ports extent buffer to btrfs-progs. extent_map.c contains a simplified extent map tree and functions that manipulate/manage extent buffer. extent state related codes are based on corresponding codes in kernel module, codes that manage extent buffer are from disk-io.c. Regards YZ --- diff -r 59fc7ac63e46 extent-cache.c --- a/extent-cache.c Fri Dec 21 16:25:35 2007 -0500 +++ b/extent-cache.c Fri Jan 04 18:59:04 2008 +0800 @@ -143,6 +143,15 @@ struct cache_extent *find_first_cache_ex return entry; } +struct cache_extent *prev_cache_extent(struct cache_extent *pe) +{ + struct rb_node *node = rb_prev(&pe->rb_node); + + if (!node) + return NULL; + return rb_entry(node, struct cache_extent, rb_node); +} + struct cache_extent *next_cache_extent(struct cache_extent *pe) { struct rb_node *node = rb_next(&pe->rb_node); diff -r 59fc7ac63e46 extent-cache.h --- a/extent-cache.h Fri Dec 21 16:25:35 2007 -0500 +++ b/extent-cache.h Fri Jan 04 18:59:04 2008 +0800 @@ -36,6 +36,7 @@ void remove_cache_extent(struct cache_tr struct cache_extent *pe); struct cache_extent *find_first_cache_extent(struct cache_tree *tree, u64 start); +struct cache_extent *prev_cache_extent(struct cache_extent *pe); struct cache_extent *next_cache_extent(struct cache_extent *pe); struct cache_extent *find_cache_extent(struct cache_tree *tree, u64 start, u64 size); diff -r 59fc7ac63e46 extent_map.c --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/extent_map.c Fri Jan 04 18:59:04 2008 +0800 @@ -0,0 +1,752 @@ +/* + * 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. + */ +#define _XOPEN_SOURCE 600 +#define __USE_XOPEN2K +#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_map.h" +#include "list.h" + +u64 cache_max = 1024 * 1024 * 32; + +void extent_map_tree_init(struct extent_map_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->refs = 1; + state->state = 0; + state->private = 0; + return state; +} + +static void free_extent_state(struct extent_state *state) +{ + state->refs--; + BUG_ON(state->refs < 0); + if (state->refs == 0) + free(state); +} + +void extent_map_tree_cleanup(struct extent_map_tree *tree) +{ + struct extent_state *es; + struct extent_buffer *eb; + struct cache_extent *cache; + + while(!list_empty(&tree->lru)) { + eb = list_entry(tree->lru.next, struct extent_buffer, lru); + if (eb->refs != 1) { + fprintf(stderr, "extent buffer leak: " + "start %Lu len %u\n", eb->start, eb->len); + eb->refs = 1; + } + free_extent_buffer(eb); + } + while (1) { + cache = find_first_cache_extent(&tree->state, 0); + if (!cache) + break; + es = container_of(cache, struct extent_state, cache_node); + remove_cache_extent(&tree->state, &es->cache_node); + free_extent_state(es); + } +} + +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_map_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); + 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(state); + remove_cache_extent(&tree->state, &state->cache_node); + 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_map_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_existing_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_map_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_existing_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_map_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); + free_extent_state(state); + } else { + merge_state(tree, state); + } + return ret; +} + +/* + * set some bits on a range in the tree. + */ +int clear_extent_bits(struct extent_map_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; + int set = 0; + +again: + prealloc = alloc_extent_state(); + if (!prealloc) + return -ENOMEM; + + /* + * this search will find the extents that end after + * our range starts + */ + node = find_first_cache_extent(&tree->state, start); + if (!node) + goto out; + state = container_of(node, struct extent_state, cache_node); + if (state->start > end) + goto out; + + /* + * | ---- 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) { + start = state->end + 1; + set |= clear_state_bit(tree, state, bits); + } 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); + goto search_again; +out: + if (prealloc) + 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_map_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; + int set; + u64 last_start; + u64 last_end; +again: + prealloc = alloc_extent_state(); + if (!prealloc) + return -ENOMEM; + + /* + * this search will find the extents that end after + * our range starts + */ + node = find_first_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) { + set = state->state & bits; + state->state |= bits; + start = state->end + 1; + merge_state(tree, state); + 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) { + set = state->state & bits; + 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); + } 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 + */ + set = state->state & bits; + err = split_state(tree, state, prealloc, end + 1); + BUG_ON(err == -EEXIST); + + state->state |= bits; + merge_state(tree, prealloc); + prealloc = NULL; +out: + if (prealloc) + free_extent_state(prealloc); + return err; +search_again: + if (start > end) + goto out; + goto again; +} + +int set_extent_dirty(struct extent_map_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_map_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_map_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 = find_first_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_map_tree *tree, u64 start, u64 end, + int bits, int filled) +{ + struct extent_state *state = NULL; + struct cache_extent *node; + int bitset = 0; + + node = find_first_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); + } + return bitset; +} + +int set_state_private(struct extent_map_tree *tree, u64 start, u64 private) +{ + struct cache_extent *node; + struct extent_state *state; + int ret = 0; + + node = find_first_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->private = private; +out: + return ret; +} + +int get_state_private(struct extent_map_tree *tree, u64 start, u64 *private) +{ + struct cache_extent *node; + struct extent_state *state; + int ret = 0; + + node = find_first_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->private; +out: + return ret; +} + +static int free_some_buffers(struct extent_map_tree *tree) +{ + u32 nrscan = 0; + struct extent_buffer *eb; + struct list_head *node, *next; + + if (tree->cache_size < cache_max) + return 0; + list_for_each_safe(node, next, &tree->lru) { + eb = list_entry(node, struct extent_buffer, lru); + if (eb->refs == 1) { + free_extent_buffer(eb); + if (tree->cache_size < cache_max) + break; + } + if (nrscan++ > 64) + break; + } + return 0; +} + +static struct extent_buffer *__alloc_extent_buffer(struct extent_map_tree *tree, + u64 bytenr, u32 blocksize) +{ + struct extent_buffer *eb; + int ret; + + eb = malloc(sizeof(struct extent_buffer) + blocksize); + if (!eb) + return NULL; + + eb->start = bytenr; + eb->len = blocksize; + eb->refs = 2; + eb->flags = 0; + eb->tree = tree; + eb->fd = -1; + eb->dev_bytenr = (u64)-1; + eb->cache_node.start = bytenr; + eb->cache_node.size = blocksize; + + free_some_buffers(tree); + ret = insert_existing_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; +} + +void free_extent_buffer(struct extent_buffer *eb) +{ + if (!eb) + return; + + eb->refs--; + BUG_ON(eb->refs < 0); + if (eb->refs == 0) { + struct extent_map_tree *tree = eb->tree; + BUG_ON(eb->flags & EXTENT_DIRTY); + list_del_init(&eb->lru); + remove_cache_extent(&tree->cache, &eb->cache_node); + BUG_ON(tree->cache_size < eb->len); + tree->cache_size -= eb->len; + free(eb); + } +} + +struct extent_buffer *find_extent_buffer(struct extent_map_tree *tree, + u64 bytenr, u32 blocksize) +{ + struct extent_buffer *eb = NULL; + struct cache_extent *cache; + + cache = find_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_map_tree *tree, + u64 start) +{ + struct extent_buffer *eb = NULL; + struct cache_extent *cache; + + cache = find_first_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_map_tree *tree, + u64 bytenr, u32 blocksize) +{ + struct extent_buffer *eb; + struct cache_extent *cache; + + cache = find_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 { + if (cache) { + eb = container_of(cache, struct extent_buffer, + cache_node); + BUG_ON(eb->refs != 1); + free_extent_buffer(eb); + } + eb = __alloc_extent_buffer(tree, bytenr, blocksize); + } + return eb; +} + +int read_extent_from_disk(struct extent_buffer *eb) +{ + int ret; + ret = pread(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 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 set_extent_buffer_uptodate(struct extent_buffer *eb) +{ + eb->flags |= EXTENT_UPTODATE; + return 0; +} + +int extent_buffer_uptodate(struct extent_buffer *eb) +{ + if (eb->flags & EXTENT_UPTODATE) + return 1; + return 0; +} + +int set_extent_buffer_dirty(struct extent_buffer *eb) +{ + struct extent_map_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_map_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 memcpy_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset, + unsigned long src_offset, unsigned long len) +{ + memcpy(dst->data + dst_offset, dst->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); +} + diff -r 59fc7ac63e46 extent_map.h --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/extent_map.h Fri Jan 04 18:59:04 2008 +0800 @@ -0,0 +1,115 @@ +/* + * 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. + */ + +#ifndef __EXTENTMAP__ +#define __EXTENTMAP__ +#include "kerncompat.h" +#include "extent-cache.h" +#include "list.h" + +#define EXTENT_DIRTY 1 +#define EXTENT_WRITEBACK (1 << 1) +#define EXTENT_UPTODATE (1 << 2) +#define EXTENT_LOCKED (1 << 3) +#define EXTENT_NEW (1 << 4) +#define EXTENT_DELALLOC (1 << 5) +#define EXTENT_DEFRAG (1 << 6) +#define EXTENT_DEFRAG_DONE (1 << 7) +#define EXTENT_BUFFER_FILLED (1 << 8) +#define EXTENT_CSUM (1 << 9) +#define EXTENT_IOBITS (EXTENT_LOCKED | EXTENT_WRITEBACK) + +struct extent_map_tree { + struct cache_tree state; + struct cache_tree cache; + struct list_head lru; + u64 cache_size; +}; + +struct extent_state { + struct cache_extent cache_node; + u64 start; + u64 end; + int refs; + unsigned long state; + u64 private; +}; + +struct extent_buffer { + struct cache_extent cache_node; + u64 start; + u64 dev_bytenr; + u32 len; + struct extent_map_tree *tree; + struct list_head lru; + int refs; + int flags; + int fd; + char data[]; +}; + +static inline void extent_buffer_get(struct extent_buffer *eb) +{ + eb->refs++; +} + +void extent_map_tree_init(struct extent_map_tree *tree); +void extent_map_tree_cleanup(struct extent_map_tree *tree); +int set_extent_bits(struct extent_map_tree *tree, u64 start, + u64 end, int bits, gfp_t mask); +int clear_extent_bits(struct extent_map_tree *tree, u64 start, + u64 end, int bits, gfp_t mask); +int find_first_extent_bit(struct extent_map_tree *tree, u64 start, + u64 *start_ret, u64 *end_ret, int bits); +int test_range_bit(struct extent_map_tree *tree, u64 start, u64 end, + int bits, int filled); +int set_extent_dirty(struct extent_map_tree *tree, u64 start, + u64 end, gfp_t mask); +int clear_extent_dirty(struct extent_map_tree *tree, u64 start, + u64 end, gfp_t mask); +int extent_buffer_uptodate(struct extent_buffer *eb); +int set_extent_buffer_uptodate(struct extent_buffer *eb); +int set_state_private(struct extent_map_tree *tree, u64 start, u64 private); +int get_state_private(struct extent_map_tree *tree, u64 start, u64 *private); +struct extent_buffer *find_extent_buffer(struct extent_map_tree *tree, + u64 bytenr, u32 blocksize); +struct extent_buffer *find_first_extent_buffer(struct extent_map_tree *tree, + u64 start); +struct extent_buffer *alloc_extent_buffer(struct extent_map_tree *tree, + u64 bytenr, u32 blocksize); +void free_extent_buffer(struct extent_buffer *eb); +int read_extent_from_disk(struct extent_buffer *eb); +int write_extent_to_disk(struct extent_buffer *eb); +int memcmp_extent_buffer(struct extent_buffer *eb, const void *ptrv, + unsigned long start, unsigned long len); +void read_extent_buffer(struct extent_buffer *eb, void *dst, + unsigned long start, unsigned long len); +void write_extent_buffer(struct extent_buffer *eb, const void *src, + unsigned long start, unsigned long len); +void copy_extent_buffer(struct extent_buffer *dst, struct extent_buffer *src, + unsigned long dst_offset, unsigned long src_offset, + unsigned long len); +void memcpy_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset, + unsigned long src_offset, unsigned long len); +void memmove_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset, + unsigned long src_offset, unsigned long len); +void memset_extent_buffer(struct extent_buffer *eb, char c, + unsigned long start, unsigned long len); +int set_extent_buffer_dirty(struct extent_buffer *eb); +int clear_extent_buffer_dirty(struct extent_buffer *eb); +#endif