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linux/fs/btrfs/free-space-tree.c

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/*
* Copyright (C) 2015 Facebook. 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 <linux/kernel.h>
#include <linux/sched/mm.h>
#include "ctree.h"
#include "disk-io.h"
#include "locking.h"
#include "free-space-tree.h"
#include "transaction.h"
static int __add_block_group_free_space(struct btrfs_trans_handle *trans,
struct btrfs_fs_info *fs_info,
struct btrfs_block_group_cache *block_group,
struct btrfs_path *path);
void set_free_space_tree_thresholds(struct btrfs_block_group_cache *cache)
{
u32 bitmap_range;
size_t bitmap_size;
u64 num_bitmaps, total_bitmap_size;
/*
* We convert to bitmaps when the disk space required for using extents
* exceeds that required for using bitmaps.
*/
bitmap_range = cache->fs_info->sectorsize * BTRFS_FREE_SPACE_BITMAP_BITS;
num_bitmaps = div_u64(cache->key.offset + bitmap_range - 1,
bitmap_range);
bitmap_size = sizeof(struct btrfs_item) + BTRFS_FREE_SPACE_BITMAP_SIZE;
total_bitmap_size = num_bitmaps * bitmap_size;
cache->bitmap_high_thresh = div_u64(total_bitmap_size,
sizeof(struct btrfs_item));
/*
* We allow for a small buffer between the high threshold and low
* threshold to avoid thrashing back and forth between the two formats.
*/
if (cache->bitmap_high_thresh > 100)
cache->bitmap_low_thresh = cache->bitmap_high_thresh - 100;
else
cache->bitmap_low_thresh = 0;
}
static int add_new_free_space_info(struct btrfs_trans_handle *trans,
struct btrfs_fs_info *fs_info,
struct btrfs_block_group_cache *block_group,
struct btrfs_path *path)
{
struct btrfs_root *root = fs_info->free_space_root;
struct btrfs_free_space_info *info;
struct btrfs_key key;
struct extent_buffer *leaf;
int ret;
key.objectid = block_group->key.objectid;
key.type = BTRFS_FREE_SPACE_INFO_KEY;
key.offset = block_group->key.offset;
ret = btrfs_insert_empty_item(trans, root, path, &key, sizeof(*info));
if (ret)
goto out;
leaf = path->nodes[0];
info = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_free_space_info);
btrfs_set_free_space_extent_count(leaf, info, 0);
btrfs_set_free_space_flags(leaf, info, 0);
btrfs_mark_buffer_dirty(leaf);
ret = 0;
out:
btrfs_release_path(path);
return ret;
}
struct btrfs_free_space_info *
search_free_space_info(struct btrfs_trans_handle *trans,
struct btrfs_fs_info *fs_info,
struct btrfs_block_group_cache *block_group,
struct btrfs_path *path, int cow)
{
struct btrfs_root *root = fs_info->free_space_root;
struct btrfs_key key;
int ret;
key.objectid = block_group->key.objectid;
key.type = BTRFS_FREE_SPACE_INFO_KEY;
key.offset = block_group->key.offset;
ret = btrfs_search_slot(trans, root, &key, path, 0, cow);
if (ret < 0)
return ERR_PTR(ret);
if (ret != 0) {
btrfs_warn(fs_info, "missing free space info for %llu",
block_group->key.objectid);
ASSERT(0);
return ERR_PTR(-ENOENT);
}
return btrfs_item_ptr(path->nodes[0], path->slots[0],
struct btrfs_free_space_info);
}
/*
* btrfs_search_slot() but we're looking for the greatest key less than the
* passed key.
*/
static int btrfs_search_prev_slot(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct btrfs_key *key, struct btrfs_path *p,
int ins_len, int cow)
{
int ret;
ret = btrfs_search_slot(trans, root, key, p, ins_len, cow);
if (ret < 0)
return ret;
if (ret == 0) {
ASSERT(0);
return -EIO;
}
if (p->slots[0] == 0) {
ASSERT(0);
return -EIO;
}
p->slots[0]--;
return 0;
}
static inline u32 free_space_bitmap_size(u64 size, u32 sectorsize)
{
return DIV_ROUND_UP((u32)div_u64(size, sectorsize), BITS_PER_BYTE);
}
static u8 *alloc_bitmap(u32 bitmap_size)
{
u8 *ret;
unsigned int nofs_flag;
/*
* GFP_NOFS doesn't work with kvmalloc(), but we really can't recurse
* into the filesystem as the free space bitmap can be modified in the
* critical section of a transaction commit.
*
* TODO: push the memalloc_nofs_{save,restore}() to the caller where we
* know that recursion is unsafe.
*/
nofs_flag = memalloc_nofs_save();
ret = kvzalloc(bitmap_size, GFP_KERNEL);
memalloc_nofs_restore(nofs_flag);
return ret;
}
int convert_free_space_to_bitmaps(struct btrfs_trans_handle *trans,
struct btrfs_fs_info *fs_info,
struct btrfs_block_group_cache *block_group,
struct btrfs_path *path)
{
struct btrfs_root *root = fs_info->free_space_root;
struct btrfs_free_space_info *info;
struct btrfs_key key, found_key;
struct extent_buffer *leaf;
u8 *bitmap, *bitmap_cursor;
u64 start, end;
u64 bitmap_range, i;
u32 bitmap_size, flags, expected_extent_count;
u32 extent_count = 0;
int done = 0, nr;
int ret;
bitmap_size = free_space_bitmap_size(block_group->key.offset,
fs_info->sectorsize);
bitmap = alloc_bitmap(bitmap_size);
if (!bitmap) {
ret = -ENOMEM;
goto out;
}
start = block_group->key.objectid;
end = block_group->key.objectid + block_group->key.offset;
key.objectid = end - 1;
key.type = (u8)-1;
key.offset = (u64)-1;
while (!done) {
ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
if (ret)
goto out;
leaf = path->nodes[0];
nr = 0;
path->slots[0]++;
while (path->slots[0] > 0) {
btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0] - 1);
if (found_key.type == BTRFS_FREE_SPACE_INFO_KEY) {
ASSERT(found_key.objectid == block_group->key.objectid);
ASSERT(found_key.offset == block_group->key.offset);
done = 1;
break;
} else if (found_key.type == BTRFS_FREE_SPACE_EXTENT_KEY) {
u64 first, last;
ASSERT(found_key.objectid >= start);
ASSERT(found_key.objectid < end);
ASSERT(found_key.objectid + found_key.offset <= end);
first = div_u64(found_key.objectid - start,
fs_info->sectorsize);
last = div_u64(found_key.objectid + found_key.offset - start,
fs_info->sectorsize);
le_bitmap_set(bitmap, first, last - first);
extent_count++;
nr++;
path->slots[0]--;
} else {
ASSERT(0);
}
}
ret = btrfs_del_items(trans, root, path, path->slots[0], nr);
if (ret)
goto out;
btrfs_release_path(path);
}
info = search_free_space_info(trans, fs_info, block_group, path, 1);
if (IS_ERR(info)) {
ret = PTR_ERR(info);
goto out;
}
leaf = path->nodes[0];
flags = btrfs_free_space_flags(leaf, info);
flags |= BTRFS_FREE_SPACE_USING_BITMAPS;
btrfs_set_free_space_flags(leaf, info, flags);
expected_extent_count = btrfs_free_space_extent_count(leaf, info);
btrfs_mark_buffer_dirty(leaf);
btrfs_release_path(path);
if (extent_count != expected_extent_count) {
btrfs_err(fs_info,
"incorrect extent count for %llu; counted %u, expected %u",
block_group->key.objectid, extent_count,
expected_extent_count);
ASSERT(0);
ret = -EIO;
goto out;
}
bitmap_cursor = bitmap;
bitmap_range = fs_info->sectorsize * BTRFS_FREE_SPACE_BITMAP_BITS;
i = start;
while (i < end) {
unsigned long ptr;
u64 extent_size;
u32 data_size;
extent_size = min(end - i, bitmap_range);
data_size = free_space_bitmap_size(extent_size,
fs_info->sectorsize);
key.objectid = i;
key.type = BTRFS_FREE_SPACE_BITMAP_KEY;
key.offset = extent_size;
ret = btrfs_insert_empty_item(trans, root, path, &key,
data_size);
if (ret)
goto out;
leaf = path->nodes[0];
ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
write_extent_buffer(leaf, bitmap_cursor, ptr,
data_size);
btrfs_mark_buffer_dirty(leaf);
btrfs_release_path(path);
i += extent_size;
bitmap_cursor += data_size;
}
ret = 0;
out:
kvfree(bitmap);
if (ret)
btrfs_abort_transaction(trans, ret);
return ret;
}
int convert_free_space_to_extents(struct btrfs_trans_handle *trans,
struct btrfs_fs_info *fs_info,
struct btrfs_block_group_cache *block_group,
struct btrfs_path *path)
{
struct btrfs_root *root = fs_info->free_space_root;
struct btrfs_free_space_info *info;
struct btrfs_key key, found_key;
struct extent_buffer *leaf;
u8 *bitmap;
u64 start, end;
/* Initialize to silence GCC. */
u64 extent_start = 0;
u64 offset;
u32 bitmap_size, flags, expected_extent_count;
int prev_bit = 0, bit, bitnr;
u32 extent_count = 0;
int done = 0, nr;
int ret;
bitmap_size = free_space_bitmap_size(block_group->key.offset,
fs_info->sectorsize);
bitmap = alloc_bitmap(bitmap_size);
if (!bitmap) {
ret = -ENOMEM;
goto out;
}
start = block_group->key.objectid;
end = block_group->key.objectid + block_group->key.offset;
key.objectid = end - 1;
key.type = (u8)-1;
key.offset = (u64)-1;
while (!done) {
ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
if (ret)
goto out;
leaf = path->nodes[0];
nr = 0;
path->slots[0]++;
while (path->slots[0] > 0) {
btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0] - 1);
if (found_key.type == BTRFS_FREE_SPACE_INFO_KEY) {
ASSERT(found_key.objectid == block_group->key.objectid);
ASSERT(found_key.offset == block_group->key.offset);
done = 1;
break;
} else if (found_key.type == BTRFS_FREE_SPACE_BITMAP_KEY) {
unsigned long ptr;
u8 *bitmap_cursor;
u32 bitmap_pos, data_size;
ASSERT(found_key.objectid >= start);
ASSERT(found_key.objectid < end);
ASSERT(found_key.objectid + found_key.offset <= end);
bitmap_pos = div_u64(found_key.objectid - start,
fs_info->sectorsize *
BITS_PER_BYTE);
bitmap_cursor = bitmap + bitmap_pos;
data_size = free_space_bitmap_size(found_key.offset,
fs_info->sectorsize);
ptr = btrfs_item_ptr_offset(leaf, path->slots[0] - 1);
read_extent_buffer(leaf, bitmap_cursor, ptr,
data_size);
nr++;
path->slots[0]--;
} else {
ASSERT(0);
}
}
ret = btrfs_del_items(trans, root, path, path->slots[0], nr);
if (ret)
goto out;
btrfs_release_path(path);
}
info = search_free_space_info(trans, fs_info, block_group, path, 1);
if (IS_ERR(info)) {
ret = PTR_ERR(info);
goto out;
}
leaf = path->nodes[0];
flags = btrfs_free_space_flags(leaf, info);
flags &= ~BTRFS_FREE_SPACE_USING_BITMAPS;
btrfs_set_free_space_flags(leaf, info, flags);
expected_extent_count = btrfs_free_space_extent_count(leaf, info);
btrfs_mark_buffer_dirty(leaf);
btrfs_release_path(path);
offset = start;
bitnr = 0;
while (offset < end) {
bit = !!le_test_bit(bitnr, bitmap);
if (prev_bit == 0 && bit == 1) {
extent_start = offset;
} else if (prev_bit == 1 && bit == 0) {
key.objectid = extent_start;
key.type = BTRFS_FREE_SPACE_EXTENT_KEY;
key.offset = offset - extent_start;
ret = btrfs_insert_empty_item(trans, root, path, &key, 0);
if (ret)
goto out;
btrfs_release_path(path);
extent_count++;
}
prev_bit = bit;
offset += fs_info->sectorsize;
bitnr++;
}
if (prev_bit == 1) {
key.objectid = extent_start;
key.type = BTRFS_FREE_SPACE_EXTENT_KEY;
key.offset = end - extent_start;
ret = btrfs_insert_empty_item(trans, root, path, &key, 0);
if (ret)
goto out;
btrfs_release_path(path);
extent_count++;
}
if (extent_count != expected_extent_count) {
btrfs_err(fs_info,
"incorrect extent count for %llu; counted %u, expected %u",
block_group->key.objectid, extent_count,
expected_extent_count);
ASSERT(0);
ret = -EIO;
goto out;
}
ret = 0;
out:
kvfree(bitmap);
if (ret)
btrfs_abort_transaction(trans, ret);
return ret;
}
static int update_free_space_extent_count(struct btrfs_trans_handle *trans,
struct btrfs_fs_info *fs_info,
struct btrfs_block_group_cache *block_group,
struct btrfs_path *path,
int new_extents)
{
struct btrfs_free_space_info *info;
u32 flags;
u32 extent_count;
int ret = 0;
if (new_extents == 0)
return 0;
info = search_free_space_info(trans, fs_info, block_group, path, 1);
if (IS_ERR(info)) {
ret = PTR_ERR(info);
goto out;
}
flags = btrfs_free_space_flags(path->nodes[0], info);
extent_count = btrfs_free_space_extent_count(path->nodes[0], info);
extent_count += new_extents;
btrfs_set_free_space_extent_count(path->nodes[0], info, extent_count);
btrfs_mark_buffer_dirty(path->nodes[0]);
btrfs_release_path(path);
if (!(flags & BTRFS_FREE_SPACE_USING_BITMAPS) &&
extent_count > block_group->bitmap_high_thresh) {
ret = convert_free_space_to_bitmaps(trans, fs_info, block_group,
path);
} else if ((flags & BTRFS_FREE_SPACE_USING_BITMAPS) &&
extent_count < block_group->bitmap_low_thresh) {
ret = convert_free_space_to_extents(trans, fs_info, block_group,
path);
}
out:
return ret;
}
int free_space_test_bit(struct btrfs_block_group_cache *block_group,
struct btrfs_path *path, u64 offset)
{
struct extent_buffer *leaf;
struct btrfs_key key;
u64 found_start, found_end;
unsigned long ptr, i;
leaf = path->nodes[0];
btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
ASSERT(key.type == BTRFS_FREE_SPACE_BITMAP_KEY);
found_start = key.objectid;
found_end = key.objectid + key.offset;
ASSERT(offset >= found_start && offset < found_end);
ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
i = div_u64(offset - found_start,
block_group->fs_info->sectorsize);
return !!extent_buffer_test_bit(leaf, ptr, i);
}
static void free_space_set_bits(struct btrfs_block_group_cache *block_group,
struct btrfs_path *path, u64 *start, u64 *size,
int bit)
{
struct btrfs_fs_info *fs_info = block_group->fs_info;
struct extent_buffer *leaf;
struct btrfs_key key;
u64 end = *start + *size;
u64 found_start, found_end;
unsigned long ptr, first, last;
leaf = path->nodes[0];
btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
ASSERT(key.type == BTRFS_FREE_SPACE_BITMAP_KEY);
found_start = key.objectid;
found_end = key.objectid + key.offset;
ASSERT(*start >= found_start && *start < found_end);
ASSERT(end > found_start);
if (end > found_end)
end = found_end;
ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
first = div_u64(*start - found_start, fs_info->sectorsize);
last = div_u64(end - found_start, fs_info->sectorsize);
if (bit)
extent_buffer_bitmap_set(leaf, ptr, first, last - first);
else
extent_buffer_bitmap_clear(leaf, ptr, first, last - first);
btrfs_mark_buffer_dirty(leaf);
*size -= end - *start;
*start = end;
}
/*
* We can't use btrfs_next_item() in modify_free_space_bitmap() because
* btrfs_next_leaf() doesn't get the path for writing. We can forgo the fancy
* tree walking in btrfs_next_leaf() anyways because we know exactly what we're
* looking for.
*/
static int free_space_next_bitmap(struct btrfs_trans_handle *trans,
struct btrfs_root *root, struct btrfs_path *p)
{
struct btrfs_key key;
if (p->slots[0] + 1 < btrfs_header_nritems(p->nodes[0])) {
p->slots[0]++;
return 0;
}
btrfs_item_key_to_cpu(p->nodes[0], &key, p->slots[0]);
btrfs_release_path(p);
key.objectid += key.offset;
key.type = (u8)-1;
key.offset = (u64)-1;
return btrfs_search_prev_slot(trans, root, &key, p, 0, 1);
}
/*
* If remove is 1, then we are removing free space, thus clearing bits in the
* bitmap. If remove is 0, then we are adding free space, thus setting bits in
* the bitmap.
*/
static int modify_free_space_bitmap(struct btrfs_trans_handle *trans,
struct btrfs_fs_info *fs_info,
struct btrfs_block_group_cache *block_group,
struct btrfs_path *path,
u64 start, u64 size, int remove)
{
struct btrfs_root *root = fs_info->free_space_root;
struct btrfs_key key;
u64 end = start + size;
u64 cur_start, cur_size;
int prev_bit, next_bit;
int new_extents;
int ret;
/*
* Read the bit for the block immediately before the extent of space if
* that block is within the block group.
*/
if (start > block_group->key.objectid) {
u64 prev_block = start - block_group->fs_info->sectorsize;
key.objectid = prev_block;
key.type = (u8)-1;
key.offset = (u64)-1;
ret = btrfs_search_prev_slot(trans, root, &key, path, 0, 1);
if (ret)
goto out;
prev_bit = free_space_test_bit(block_group, path, prev_block);
/* The previous block may have been in the previous bitmap. */
btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
if (start >= key.objectid + key.offset) {
ret = free_space_next_bitmap(trans, root, path);
if (ret)
goto out;
}
} else {
key.objectid = start;
key.type = (u8)-1;
key.offset = (u64)-1;
ret = btrfs_search_prev_slot(trans, root, &key, path, 0, 1);
if (ret)
goto out;
prev_bit = -1;
}
/*
* Iterate over all of the bitmaps overlapped by the extent of space,
* clearing/setting bits as required.
*/
cur_start = start;
cur_size = size;
while (1) {
free_space_set_bits(block_group, path, &cur_start, &cur_size,
!remove);
if (cur_size == 0)
break;
ret = free_space_next_bitmap(trans, root, path);
if (ret)
goto out;
}
/*
* Read the bit for the block immediately after the extent of space if
* that block is within the block group.
*/
if (end < block_group->key.objectid + block_group->key.offset) {
/* The next block may be in the next bitmap. */
btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
if (end >= key.objectid + key.offset) {
ret = free_space_next_bitmap(trans, root, path);
if (ret)
goto out;
}
next_bit = free_space_test_bit(block_group, path, end);
} else {
next_bit = -1;
}
if (remove) {
new_extents = -1;
if (prev_bit == 1) {
/* Leftover on the left. */
new_extents++;
}
if (next_bit == 1) {
/* Leftover on the right. */
new_extents++;
}
} else {
new_extents = 1;
if (prev_bit == 1) {
/* Merging with neighbor on the left. */
new_extents--;
}
if (next_bit == 1) {
/* Merging with neighbor on the right. */
new_extents--;
}
}
btrfs_release_path(path);
ret = update_free_space_extent_count(trans, fs_info, block_group, path,
new_extents);
out:
return ret;
}
static int remove_free_space_extent(struct btrfs_trans_handle *trans,
struct btrfs_fs_info *fs_info,
struct btrfs_block_group_cache *block_group,
struct btrfs_path *path,
u64 start, u64 size)
{
struct btrfs_root *root = fs_info->free_space_root;
struct btrfs_key key;
u64 found_start, found_end;
u64 end = start + size;
int new_extents = -1;
int ret;
key.objectid = start;
key.type = (u8)-1;
key.offset = (u64)-1;
ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
if (ret)
goto out;
btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
ASSERT(key.type == BTRFS_FREE_SPACE_EXTENT_KEY);
found_start = key.objectid;
found_end = key.objectid + key.offset;
ASSERT(start >= found_start && end <= found_end);
/*
* Okay, now that we've found the free space extent which contains the
* free space that we are removing, there are four cases:
*
* 1. We're using the whole extent: delete the key we found and
* decrement the free space extent count.
* 2. We are using part of the extent starting at the beginning: delete
* the key we found and insert a new key representing the leftover at
* the end. There is no net change in the number of extents.
* 3. We are using part of the extent ending at the end: delete the key
* we found and insert a new key representing the leftover at the
* beginning. There is no net change in the number of extents.
* 4. We are using part of the extent in the middle: delete the key we
* found and insert two new keys representing the leftovers on each
* side. Where we used to have one extent, we now have two, so increment
* the extent count. We may need to convert the block group to bitmaps
* as a result.
*/
/* Delete the existing key (cases 1-4). */
ret = btrfs_del_item(trans, root, path);
if (ret)
goto out;
/* Add a key for leftovers at the beginning (cases 3 and 4). */
if (start > found_start) {
key.objectid = found_start;
key.type = BTRFS_FREE_SPACE_EXTENT_KEY;
key.offset = start - found_start;
btrfs_release_path(path);
ret = btrfs_insert_empty_item(trans, root, path, &key, 0);
if (ret)
goto out;
new_extents++;
}
/* Add a key for leftovers at the end (cases 2 and 4). */
if (end < found_end) {
key.objectid = end;
key.type = BTRFS_FREE_SPACE_EXTENT_KEY;
key.offset = found_end - end;
btrfs_release_path(path);
ret = btrfs_insert_empty_item(trans, root, path, &key, 0);
if (ret)
goto out;
new_extents++;
}
btrfs_release_path(path);
ret = update_free_space_extent_count(trans, fs_info, block_group, path,
new_extents);
out:
return ret;
}
int __remove_from_free_space_tree(struct btrfs_trans_handle *trans,
struct btrfs_fs_info *fs_info,
struct btrfs_block_group_cache *block_group,
struct btrfs_path *path, u64 start, u64 size)
{
struct btrfs_free_space_info *info;
u32 flags;
int ret;
if (block_group->needs_free_space) {
ret = __add_block_group_free_space(trans, fs_info, block_group,
path);
if (ret)
return ret;
}
info = search_free_space_info(NULL, fs_info, block_group, path, 0);
if (IS_ERR(info))
return PTR_ERR(info);
flags = btrfs_free_space_flags(path->nodes[0], info);
btrfs_release_path(path);
if (flags & BTRFS_FREE_SPACE_USING_BITMAPS) {
return modify_free_space_bitmap(trans, fs_info, block_group,
path, start, size, 1);
} else {
return remove_free_space_extent(trans, fs_info, block_group,
path, start, size);
}
}
int remove_from_free_space_tree(struct btrfs_trans_handle *trans,
struct btrfs_fs_info *fs_info,
u64 start, u64 size)
{
struct btrfs_block_group_cache *block_group;
struct btrfs_path *path;
int ret;
if (!btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE))
return 0;
path = btrfs_alloc_path();
if (!path) {
ret = -ENOMEM;
goto out;
}
block_group = btrfs_lookup_block_group(fs_info, start);
if (!block_group) {
ASSERT(0);
ret = -ENOENT;
goto out;
}
mutex_lock(&block_group->free_space_lock);
ret = __remove_from_free_space_tree(trans, fs_info, block_group, path,
start, size);
mutex_unlock(&block_group->free_space_lock);
btrfs_put_block_group(block_group);
out:
btrfs_free_path(path);
if (ret)
btrfs_abort_transaction(trans, ret);
return ret;
}
static int add_free_space_extent(struct btrfs_trans_handle *trans,
struct btrfs_fs_info *fs_info,
struct btrfs_block_group_cache *block_group,
struct btrfs_path *path,
u64 start, u64 size)
{
struct btrfs_root *root = fs_info->free_space_root;
struct btrfs_key key, new_key;
u64 found_start, found_end;
u64 end = start + size;
int new_extents = 1;
int ret;
/*
* We are adding a new extent of free space, but we need to merge
* extents. There are four cases here:
*
* 1. The new extent does not have any immediate neighbors to merge
* with: add the new key and increment the free space extent count. We
* may need to convert the block group to bitmaps as a result.
* 2. The new extent has an immediate neighbor before it: remove the
* previous key and insert a new key combining both of them. There is no
* net change in the number of extents.
* 3. The new extent has an immediate neighbor after it: remove the next
* key and insert a new key combining both of them. There is no net
* change in the number of extents.
* 4. The new extent has immediate neighbors on both sides: remove both
* of the keys and insert a new key combining all of them. Where we used
* to have two extents, we now have one, so decrement the extent count.
*/
new_key.objectid = start;
new_key.type = BTRFS_FREE_SPACE_EXTENT_KEY;
new_key.offset = size;
/* Search for a neighbor on the left. */
if (start == block_group->key.objectid)
goto right;
key.objectid = start - 1;
key.type = (u8)-1;
key.offset = (u64)-1;
ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
if (ret)
goto out;
btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
if (key.type != BTRFS_FREE_SPACE_EXTENT_KEY) {
ASSERT(key.type == BTRFS_FREE_SPACE_INFO_KEY);
btrfs_release_path(path);
goto right;
}
found_start = key.objectid;
found_end = key.objectid + key.offset;
ASSERT(found_start >= block_group->key.objectid &&
found_end > block_group->key.objectid);
ASSERT(found_start < start && found_end <= start);
/*
* Delete the neighbor on the left and absorb it into the new key (cases
* 2 and 4).
*/
if (found_end == start) {
ret = btrfs_del_item(trans, root, path);
if (ret)
goto out;
new_key.objectid = found_start;
new_key.offset += key.offset;
new_extents--;
}
btrfs_release_path(path);
right:
/* Search for a neighbor on the right. */
if (end == block_group->key.objectid + block_group->key.offset)
goto insert;
key.objectid = end;
key.type = (u8)-1;
key.offset = (u64)-1;
ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
if (ret)
goto out;
btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
if (key.type != BTRFS_FREE_SPACE_EXTENT_KEY) {
ASSERT(key.type == BTRFS_FREE_SPACE_INFO_KEY);
btrfs_release_path(path);
goto insert;
}
found_start = key.objectid;
found_end = key.objectid + key.offset;
ASSERT(found_start >= block_group->key.objectid &&
found_end > block_group->key.objectid);
ASSERT((found_start < start && found_end <= start) ||
(found_start >= end && found_end > end));
/*
* Delete the neighbor on the right and absorb it into the new key
* (cases 3 and 4).
*/
if (found_start == end) {
ret = btrfs_del_item(trans, root, path);
if (ret)
goto out;
new_key.offset += key.offset;
new_extents--;
}
btrfs_release_path(path);
insert:
/* Insert the new key (cases 1-4). */
ret = btrfs_insert_empty_item(trans, root, path, &new_key, 0);
if (ret)
goto out;
btrfs_release_path(path);
ret = update_free_space_extent_count(trans, fs_info, block_group, path,
new_extents);
out:
return ret;
}
int __add_to_free_space_tree(struct btrfs_trans_handle *trans,
struct btrfs_fs_info *fs_info,
struct btrfs_block_group_cache *block_group,
struct btrfs_path *path, u64 start, u64 size)
{
struct btrfs_free_space_info *info;
u32 flags;
int ret;
if (block_group->needs_free_space) {
ret = __add_block_group_free_space(trans, fs_info, block_group,
path);
if (ret)
return ret;
}
info = search_free_space_info(NULL, fs_info, block_group, path, 0);
if (IS_ERR(info))
return PTR_ERR(info);
flags = btrfs_free_space_flags(path->nodes[0], info);
btrfs_release_path(path);
if (flags & BTRFS_FREE_SPACE_USING_BITMAPS) {
return modify_free_space_bitmap(trans, fs_info, block_group,
path, start, size, 0);
} else {
return add_free_space_extent(trans, fs_info, block_group, path,
start, size);
}
}
int add_to_free_space_tree(struct btrfs_trans_handle *trans,
struct btrfs_fs_info *fs_info,
u64 start, u64 size)
{
struct btrfs_block_group_cache *block_group;
struct btrfs_path *path;
int ret;
if (!btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE))
return 0;
path = btrfs_alloc_path();
if (!path) {
ret = -ENOMEM;
goto out;
}
block_group = btrfs_lookup_block_group(fs_info, start);
if (!block_group) {
ASSERT(0);
ret = -ENOENT;
goto out;
}
mutex_lock(&block_group->free_space_lock);
ret = __add_to_free_space_tree(trans, fs_info, block_group, path, start,
size);
mutex_unlock(&block_group->free_space_lock);
btrfs_put_block_group(block_group);
out:
btrfs_free_path(path);
if (ret)
btrfs_abort_transaction(trans, ret);
return ret;
}
/*
* Populate the free space tree by walking the extent tree. Operations on the
* extent tree that happen as a result of writes to the free space tree will go
* through the normal add/remove hooks.
*/
static int populate_free_space_tree(struct btrfs_trans_handle *trans,
struct btrfs_fs_info *fs_info,
struct btrfs_block_group_cache *block_group)
{
struct btrfs_root *extent_root = fs_info->extent_root;
struct btrfs_path *path, *path2;
struct btrfs_key key;
u64 start, end;
int ret;
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
path->reada = 1;
path2 = btrfs_alloc_path();
if (!path2) {
btrfs_free_path(path);
return -ENOMEM;
}
ret = add_new_free_space_info(trans, fs_info, block_group, path2);
if (ret)
goto out;
mutex_lock(&block_group->free_space_lock);
/*
* Iterate through all of the extent and metadata items in this block
* group, adding the free space between them and the free space at the
* end. Note that EXTENT_ITEM and METADATA_ITEM are less than
* BLOCK_GROUP_ITEM, so an extent may precede the block group that it's
* contained in.
*/
key.objectid = block_group->key.objectid;
key.type = BTRFS_EXTENT_ITEM_KEY;
key.offset = 0;
ret = btrfs_search_slot_for_read(extent_root, &key, path, 1, 0);
if (ret < 0)
goto out_locked;
ASSERT(ret == 0);
start = block_group->key.objectid;
end = block_group->key.objectid + block_group->key.offset;
while (1) {
btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
if (key.type == BTRFS_EXTENT_ITEM_KEY ||
key.type == BTRFS_METADATA_ITEM_KEY) {
if (key.objectid >= end)
break;
if (start < key.objectid) {
ret = __add_to_free_space_tree(trans, fs_info,
block_group,
path2, start,
key.objectid -
start);
if (ret)
goto out_locked;
}
start = key.objectid;
if (key.type == BTRFS_METADATA_ITEM_KEY)
start += fs_info->nodesize;
else
start += key.offset;
} else if (key.type == BTRFS_BLOCK_GROUP_ITEM_KEY) {
if (key.objectid != block_group->key.objectid)
break;
}
ret = btrfs_next_item(extent_root, path);
if (ret < 0)
goto out_locked;
if (ret)
break;
}
if (start < end) {
ret = __add_to_free_space_tree(trans, fs_info, block_group,
path2, start, end - start);
if (ret)
goto out_locked;
}
ret = 0;
out_locked:
mutex_unlock(&block_group->free_space_lock);
out:
btrfs_free_path(path2);
btrfs_free_path(path);
return ret;
}
int btrfs_create_free_space_tree(struct btrfs_fs_info *fs_info)
{
struct btrfs_trans_handle *trans;
struct btrfs_root *tree_root = fs_info->tree_root;
struct btrfs_root *free_space_root;
struct btrfs_block_group_cache *block_group;
struct rb_node *node;
int ret;
trans = btrfs_start_transaction(tree_root, 0);
if (IS_ERR(trans))
return PTR_ERR(trans);
set_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags);
free_space_root = btrfs_create_tree(trans, fs_info,
BTRFS_FREE_SPACE_TREE_OBJECTID);
if (IS_ERR(free_space_root)) {
ret = PTR_ERR(free_space_root);
goto abort;
}
fs_info->free_space_root = free_space_root;
node = rb_first(&fs_info->block_group_cache_tree);
while (node) {
block_group = rb_entry(node, struct btrfs_block_group_cache,
cache_node);
ret = populate_free_space_tree(trans, fs_info, block_group);
if (ret)
goto abort;
node = rb_next(node);
}
btrfs_set_fs_compat_ro(fs_info, FREE_SPACE_TREE);
btrfs_set_fs_compat_ro(fs_info, FREE_SPACE_TREE_VALID);
clear_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags);
return btrfs_commit_transaction(trans);
abort:
clear_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags);
btrfs_abort_transaction(trans, ret);
btrfs_end_transaction(trans);
return ret;
}
static int clear_free_space_tree(struct btrfs_trans_handle *trans,
struct btrfs_root *root)
{
struct btrfs_path *path;
struct btrfs_key key;
int nr;
int ret;
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
path->leave_spinning = 1;
key.objectid = 0;
key.type = 0;
key.offset = 0;
while (1) {
ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
if (ret < 0)
goto out;
nr = btrfs_header_nritems(path->nodes[0]);
if (!nr)
break;
path->slots[0] = 0;
ret = btrfs_del_items(trans, root, path, 0, nr);
if (ret)
goto out;
btrfs_release_path(path);
}
ret = 0;
out:
btrfs_free_path(path);
return ret;
}
int btrfs_clear_free_space_tree(struct btrfs_fs_info *fs_info)
{
struct btrfs_trans_handle *trans;
struct btrfs_root *tree_root = fs_info->tree_root;
struct btrfs_root *free_space_root = fs_info->free_space_root;
int ret;
trans = btrfs_start_transaction(tree_root, 0);
if (IS_ERR(trans))
return PTR_ERR(trans);
btrfs_clear_fs_compat_ro(fs_info, FREE_SPACE_TREE);
btrfs_clear_fs_compat_ro(fs_info, FREE_SPACE_TREE_VALID);
fs_info->free_space_root = NULL;
ret = clear_free_space_tree(trans, free_space_root);
if (ret)
goto abort;
ret = btrfs_del_root(trans, tree_root, &free_space_root->root_key);
if (ret)
goto abort;
list_del(&free_space_root->dirty_list);
btrfs_tree_lock(free_space_root->node);
clean_tree_block(fs_info, free_space_root->node);
btrfs_tree_unlock(free_space_root->node);
btrfs_free_tree_block(trans, free_space_root, free_space_root->node,
0, 1);
free_extent_buffer(free_space_root->node);
free_extent_buffer(free_space_root->commit_root);
kfree(free_space_root);
return btrfs_commit_transaction(trans);
abort:
btrfs_abort_transaction(trans, ret);
btrfs_end_transaction(trans);
return ret;
}
static int __add_block_group_free_space(struct btrfs_trans_handle *trans,
struct btrfs_fs_info *fs_info,
struct btrfs_block_group_cache *block_group,
struct btrfs_path *path)
{
u64 start, end;
int ret;
start = block_group->key.objectid;
end = block_group->key.objectid + block_group->key.offset;
block_group->needs_free_space = 0;
ret = add_new_free_space_info(trans, fs_info, block_group, path);
if (ret)
return ret;
return __add_to_free_space_tree(trans, fs_info, block_group, path,
block_group->key.objectid,
block_group->key.offset);
}
int add_block_group_free_space(struct btrfs_trans_handle *trans,
struct btrfs_fs_info *fs_info,
struct btrfs_block_group_cache *block_group)
{
struct btrfs_path *path = NULL;
int ret = 0;
if (!btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE))
return 0;
mutex_lock(&block_group->free_space_lock);
if (!block_group->needs_free_space)
goto out;
path = btrfs_alloc_path();
if (!path) {
ret = -ENOMEM;
goto out;
}
ret = __add_block_group_free_space(trans, fs_info, block_group, path);
out:
btrfs_free_path(path);
mutex_unlock(&block_group->free_space_lock);
if (ret)
btrfs_abort_transaction(trans, ret);
return ret;
}
int remove_block_group_free_space(struct btrfs_trans_handle *trans,
struct btrfs_fs_info *fs_info,
struct btrfs_block_group_cache *block_group)
{
struct btrfs_root *root = fs_info->free_space_root;
struct btrfs_path *path;
struct btrfs_key key, found_key;
struct extent_buffer *leaf;
u64 start, end;
int done = 0, nr;
int ret;
if (!btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE))
return 0;
if (block_group->needs_free_space) {
/* We never added this block group to the free space tree. */
return 0;
}
path = btrfs_alloc_path();
if (!path) {
ret = -ENOMEM;
goto out;
}
start = block_group->key.objectid;
end = block_group->key.objectid + block_group->key.offset;
key.objectid = end - 1;
key.type = (u8)-1;
key.offset = (u64)-1;
while (!done) {
ret = btrfs_search_prev_slot(trans, root, &key, path, -1, 1);
if (ret)
goto out;
leaf = path->nodes[0];
nr = 0;
path->slots[0]++;
while (path->slots[0] > 0) {
btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0] - 1);
if (found_key.type == BTRFS_FREE_SPACE_INFO_KEY) {
ASSERT(found_key.objectid == block_group->key.objectid);
ASSERT(found_key.offset == block_group->key.offset);
done = 1;
nr++;
path->slots[0]--;
break;
} else if (found_key.type == BTRFS_FREE_SPACE_EXTENT_KEY ||
found_key.type == BTRFS_FREE_SPACE_BITMAP_KEY) {
ASSERT(found_key.objectid >= start);
ASSERT(found_key.objectid < end);
ASSERT(found_key.objectid + found_key.offset <= end);
nr++;
path->slots[0]--;
} else {
ASSERT(0);
}
}
ret = btrfs_del_items(trans, root, path, path->slots[0], nr);
if (ret)
goto out;
btrfs_release_path(path);
}
ret = 0;
out:
btrfs_free_path(path);
if (ret)
btrfs_abort_transaction(trans, ret);
return ret;
}
static int load_free_space_bitmaps(struct btrfs_caching_control *caching_ctl,
struct btrfs_path *path,
u32 expected_extent_count)
{
struct btrfs_block_group_cache *block_group;
struct btrfs_fs_info *fs_info;
struct btrfs_root *root;
struct btrfs_key key;
int prev_bit = 0, bit;
/* Initialize to silence GCC. */
u64 extent_start = 0;
u64 end, offset;
u64 total_found = 0;
u32 extent_count = 0;
int ret;
block_group = caching_ctl->block_group;
fs_info = block_group->fs_info;
root = fs_info->free_space_root;
end = block_group->key.objectid + block_group->key.offset;
while (1) {
ret = btrfs_next_item(root, path);
if (ret < 0)
goto out;
if (ret)
break;
btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
if (key.type == BTRFS_FREE_SPACE_INFO_KEY)
break;
ASSERT(key.type == BTRFS_FREE_SPACE_BITMAP_KEY);
ASSERT(key.objectid < end && key.objectid + key.offset <= end);
caching_ctl->progress = key.objectid;
offset = key.objectid;
while (offset < key.objectid + key.offset) {
bit = free_space_test_bit(block_group, path, offset);
if (prev_bit == 0 && bit == 1) {
extent_start = offset;
} else if (prev_bit == 1 && bit == 0) {
total_found += add_new_free_space(block_group,
fs_info,
extent_start,
offset);
if (total_found > CACHING_CTL_WAKE_UP) {
total_found = 0;
wake_up(&caching_ctl->wait);
}
extent_count++;
}
prev_bit = bit;
offset += fs_info->sectorsize;
}
}
if (prev_bit == 1) {
total_found += add_new_free_space(block_group, fs_info,
extent_start, end);
extent_count++;
}
if (extent_count != expected_extent_count) {
btrfs_err(fs_info,
"incorrect extent count for %llu; counted %u, expected %u",
block_group->key.objectid, extent_count,
expected_extent_count);
ASSERT(0);
ret = -EIO;
goto out;
}
caching_ctl->progress = (u64)-1;
ret = 0;
out:
return ret;
}
static int load_free_space_extents(struct btrfs_caching_control *caching_ctl,
struct btrfs_path *path,
u32 expected_extent_count)
{
struct btrfs_block_group_cache *block_group;
struct btrfs_fs_info *fs_info;
struct btrfs_root *root;
struct btrfs_key key;
u64 end;
u64 total_found = 0;
u32 extent_count = 0;
int ret;
block_group = caching_ctl->block_group;
fs_info = block_group->fs_info;
root = fs_info->free_space_root;
end = block_group->key.objectid + block_group->key.offset;
while (1) {
ret = btrfs_next_item(root, path);
if (ret < 0)
goto out;
if (ret)
break;
btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
if (key.type == BTRFS_FREE_SPACE_INFO_KEY)
break;
ASSERT(key.type == BTRFS_FREE_SPACE_EXTENT_KEY);
ASSERT(key.objectid < end && key.objectid + key.offset <= end);
caching_ctl->progress = key.objectid;
total_found += add_new_free_space(block_group, fs_info,
key.objectid,
key.objectid + key.offset);
if (total_found > CACHING_CTL_WAKE_UP) {
total_found = 0;
wake_up(&caching_ctl->wait);
}
extent_count++;
}
if (extent_count != expected_extent_count) {
btrfs_err(fs_info,
"incorrect extent count for %llu; counted %u, expected %u",
block_group->key.objectid, extent_count,
expected_extent_count);
ASSERT(0);
ret = -EIO;
goto out;
}
caching_ctl->progress = (u64)-1;
ret = 0;
out:
return ret;
}
int load_free_space_tree(struct btrfs_caching_control *caching_ctl)
{
struct btrfs_block_group_cache *block_group;
struct btrfs_fs_info *fs_info;
struct btrfs_free_space_info *info;
struct btrfs_path *path;
u32 extent_count, flags;
int ret;
block_group = caching_ctl->block_group;
fs_info = block_group->fs_info;
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
/*
* Just like caching_thread() doesn't want to deadlock on the extent
* tree, we don't want to deadlock on the free space tree.
*/
path->skip_locking = 1;
path->search_commit_root = 1;
path->reada = 1;
info = search_free_space_info(NULL, fs_info, block_group, path, 0);
if (IS_ERR(info)) {
ret = PTR_ERR(info);
goto out;
}
extent_count = btrfs_free_space_extent_count(path->nodes[0], info);
flags = btrfs_free_space_flags(path->nodes[0], info);
/*
* We left path pointing to the free space info item, so now
* load_free_space_foo can just iterate through the free space tree from
* there.
*/
if (flags & BTRFS_FREE_SPACE_USING_BITMAPS)
ret = load_free_space_bitmaps(caching_ctl, path, extent_count);
else
ret = load_free_space_extents(caching_ctl, path, extent_count);
out:
btrfs_free_path(path);
return ret;
}
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