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linux-sg2042/fs/btrfs/free-space-cache.c

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/*
* Copyright (C) 2008 Red Hat. 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/pagemap.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/math64.h>
#include "ctree.h"
#include "free-space-cache.h"
#include "transaction.h"
#include "disk-io.h"
#include "extent_io.h"
#define BITS_PER_BITMAP (PAGE_CACHE_SIZE * 8)
#define MAX_CACHE_BYTES_PER_GIG (32 * 1024)
static void recalculate_thresholds(struct btrfs_block_group_cache
*block_group);
static int link_free_space(struct btrfs_block_group_cache *block_group,
struct btrfs_free_space *info);
struct inode *lookup_free_space_inode(struct btrfs_root *root,
struct btrfs_block_group_cache
*block_group, struct btrfs_path *path)
{
struct btrfs_key key;
struct btrfs_key location;
struct btrfs_disk_key disk_key;
struct btrfs_free_space_header *header;
struct extent_buffer *leaf;
struct inode *inode = NULL;
int ret;
spin_lock(&block_group->lock);
if (block_group->inode)
inode = igrab(block_group->inode);
spin_unlock(&block_group->lock);
if (inode)
return inode;
key.objectid = BTRFS_FREE_SPACE_OBJECTID;
key.offset = block_group->key.objectid;
key.type = 0;
ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
if (ret < 0)
return ERR_PTR(ret);
if (ret > 0) {
btrfs_release_path(path);
return ERR_PTR(-ENOENT);
}
leaf = path->nodes[0];
header = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_free_space_header);
btrfs_free_space_key(leaf, header, &disk_key);
btrfs_disk_key_to_cpu(&location, &disk_key);
btrfs_release_path(path);
inode = btrfs_iget(root->fs_info->sb, &location, root, NULL);
if (!inode)
return ERR_PTR(-ENOENT);
if (IS_ERR(inode))
return inode;
if (is_bad_inode(inode)) {
iput(inode);
return ERR_PTR(-ENOENT);
}
inode->i_mapping->flags &= ~__GFP_FS;
spin_lock(&block_group->lock);
if (!root->fs_info->closing) {
block_group->inode = igrab(inode);
block_group->iref = 1;
}
spin_unlock(&block_group->lock);
return inode;
}
int create_free_space_inode(struct btrfs_root *root,
struct btrfs_trans_handle *trans,
struct btrfs_block_group_cache *block_group,
struct btrfs_path *path)
{
struct btrfs_key key;
struct btrfs_disk_key disk_key;
struct btrfs_free_space_header *header;
struct btrfs_inode_item *inode_item;
struct extent_buffer *leaf;
u64 objectid;
int ret;
ret = btrfs_find_free_objectid(trans, root, 0, &objectid);
if (ret < 0)
return ret;
ret = btrfs_insert_empty_inode(trans, root, path, objectid);
if (ret)
return ret;
leaf = path->nodes[0];
inode_item = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_inode_item);
btrfs_item_key(leaf, &disk_key, path->slots[0]);
memset_extent_buffer(leaf, 0, (unsigned long)inode_item,
sizeof(*inode_item));
btrfs_set_inode_generation(leaf, inode_item, trans->transid);
btrfs_set_inode_size(leaf, inode_item, 0);
btrfs_set_inode_nbytes(leaf, inode_item, 0);
btrfs_set_inode_uid(leaf, inode_item, 0);
btrfs_set_inode_gid(leaf, inode_item, 0);
btrfs_set_inode_mode(leaf, inode_item, S_IFREG | 0600);
btrfs_set_inode_flags(leaf, inode_item, BTRFS_INODE_NOCOMPRESS |
BTRFS_INODE_PREALLOC | BTRFS_INODE_NODATASUM);
btrfs_set_inode_nlink(leaf, inode_item, 1);
btrfs_set_inode_transid(leaf, inode_item, trans->transid);
btrfs_set_inode_block_group(leaf, inode_item,
block_group->key.objectid);
btrfs_mark_buffer_dirty(leaf);
btrfs_release_path(path);
key.objectid = BTRFS_FREE_SPACE_OBJECTID;
key.offset = block_group->key.objectid;
key.type = 0;
ret = btrfs_insert_empty_item(trans, root, path, &key,
sizeof(struct btrfs_free_space_header));
if (ret < 0) {
btrfs_release_path(path);
return ret;
}
leaf = path->nodes[0];
header = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_free_space_header);
memset_extent_buffer(leaf, 0, (unsigned long)header, sizeof(*header));
btrfs_set_free_space_key(leaf, header, &disk_key);
btrfs_mark_buffer_dirty(leaf);
btrfs_release_path(path);
return 0;
}
int btrfs_truncate_free_space_cache(struct btrfs_root *root,
struct btrfs_trans_handle *trans,
struct btrfs_path *path,
struct inode *inode)
{
loff_t oldsize;
int ret = 0;
trans->block_rsv = root->orphan_block_rsv;
ret = btrfs_block_rsv_check(trans, root,
root->orphan_block_rsv,
0, 5);
if (ret)
return ret;
oldsize = i_size_read(inode);
btrfs_i_size_write(inode, 0);
truncate_pagecache(inode, oldsize, 0);
/*
* We don't need an orphan item because truncating the free space cache
* will never be split across transactions.
*/
ret = btrfs_truncate_inode_items(trans, root, inode,
0, BTRFS_EXTENT_DATA_KEY);
if (ret) {
WARN_ON(1);
return ret;
}
return btrfs_update_inode(trans, root, inode);
}
static int readahead_cache(struct inode *inode)
{
struct file_ra_state *ra;
unsigned long last_index;
ra = kzalloc(sizeof(*ra), GFP_NOFS);
if (!ra)
return -ENOMEM;
file_ra_state_init(ra, inode->i_mapping);
last_index = (i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT;
page_cache_sync_readahead(inode->i_mapping, ra, NULL, 0, last_index);
kfree(ra);
return 0;
}
int load_free_space_cache(struct btrfs_fs_info *fs_info,
struct btrfs_block_group_cache *block_group)
{
struct btrfs_root *root = fs_info->tree_root;
struct inode *inode;
struct btrfs_free_space_header *header;
struct extent_buffer *leaf;
struct page *page;
struct btrfs_path *path;
u32 *checksums = NULL, *crc;
char *disk_crcs = NULL;
struct btrfs_key key;
struct list_head bitmaps;
u64 num_entries;
u64 num_bitmaps;
u64 generation;
u64 used = btrfs_block_group_used(&block_group->item);
u32 cur_crc = ~(u32)0;
pgoff_t index = 0;
unsigned long first_page_offset;
int num_checksums;
int ret = 0;
/*
* If we're unmounting then just return, since this does a search on the
* normal root and not the commit root and we could deadlock.
*/
smp_mb();
if (fs_info->closing)
return 0;
/*
* If this block group has been marked to be cleared for one reason or
* another then we can't trust the on disk cache, so just return.
*/
spin_lock(&block_group->lock);
if (block_group->disk_cache_state != BTRFS_DC_WRITTEN) {
spin_unlock(&block_group->lock);
return 0;
}
spin_unlock(&block_group->lock);
INIT_LIST_HEAD(&bitmaps);
path = btrfs_alloc_path();
if (!path)
return 0;
inode = lookup_free_space_inode(root, block_group, path);
if (IS_ERR(inode)) {
btrfs_free_path(path);
return 0;
}
/* Nothing in the space cache, goodbye */
if (!i_size_read(inode)) {
btrfs_free_path(path);
goto out;
}
key.objectid = BTRFS_FREE_SPACE_OBJECTID;
key.offset = block_group->key.objectid;
key.type = 0;
ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
if (ret) {
btrfs_free_path(path);
goto out;
}
leaf = path->nodes[0];
header = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_free_space_header);
num_entries = btrfs_free_space_entries(leaf, header);
num_bitmaps = btrfs_free_space_bitmaps(leaf, header);
generation = btrfs_free_space_generation(leaf, header);
btrfs_free_path(path);
if (BTRFS_I(inode)->generation != generation) {
printk(KERN_ERR "btrfs: free space inode generation (%llu) did"
" not match free space cache generation (%llu) for "
"block group %llu\n",
(unsigned long long)BTRFS_I(inode)->generation,
(unsigned long long)generation,
(unsigned long long)block_group->key.objectid);
goto free_cache;
}
if (!num_entries)
goto out;
/* Setup everything for doing checksumming */
num_checksums = i_size_read(inode) / PAGE_CACHE_SIZE;
checksums = crc = kzalloc(sizeof(u32) * num_checksums, GFP_NOFS);
if (!checksums)
goto out;
first_page_offset = (sizeof(u32) * num_checksums) + sizeof(u64);
disk_crcs = kzalloc(first_page_offset, GFP_NOFS);
if (!disk_crcs)
goto out;
ret = readahead_cache(inode);
if (ret) {
ret = 0;
goto out;
}
while (1) {
struct btrfs_free_space_entry *entry;
struct btrfs_free_space *e;
void *addr;
unsigned long offset = 0;
unsigned long start_offset = 0;
int need_loop = 0;
if (!num_entries && !num_bitmaps)
break;
if (index == 0) {
start_offset = first_page_offset;
offset = start_offset;
}
page = grab_cache_page(inode->i_mapping, index);
if (!page) {
ret = 0;
goto free_cache;
}
if (!PageUptodate(page)) {
btrfs_readpage(NULL, page);
lock_page(page);
if (!PageUptodate(page)) {
unlock_page(page);
page_cache_release(page);
printk(KERN_ERR "btrfs: error reading free "
"space cache: %llu\n",
(unsigned long long)
block_group->key.objectid);
goto free_cache;
}
}
addr = kmap(page);
if (index == 0) {
u64 *gen;
memcpy(disk_crcs, addr, first_page_offset);
gen = addr + (sizeof(u32) * num_checksums);
if (*gen != BTRFS_I(inode)->generation) {
printk(KERN_ERR "btrfs: space cache generation"
" (%llu) does not match inode (%llu) "
"for block group %llu\n",
(unsigned long long)*gen,
(unsigned long long)
BTRFS_I(inode)->generation,
(unsigned long long)
block_group->key.objectid);
kunmap(page);
unlock_page(page);
page_cache_release(page);
goto free_cache;
}
crc = (u32 *)disk_crcs;
}
entry = addr + start_offset;
/* First lets check our crc before we do anything fun */
cur_crc = ~(u32)0;
cur_crc = btrfs_csum_data(root, addr + start_offset, cur_crc,
PAGE_CACHE_SIZE - start_offset);
btrfs_csum_final(cur_crc, (char *)&cur_crc);
if (cur_crc != *crc) {
printk(KERN_ERR "btrfs: crc mismatch for page %lu in "
"block group %llu\n", index,
(unsigned long long)block_group->key.objectid);
kunmap(page);
unlock_page(page);
page_cache_release(page);
goto free_cache;
}
crc++;
while (1) {
if (!num_entries)
break;
need_loop = 1;
e = kmem_cache_zalloc(btrfs_free_space_cachep,
GFP_NOFS);
if (!e) {
kunmap(page);
unlock_page(page);
page_cache_release(page);
goto free_cache;
}
e->offset = le64_to_cpu(entry->offset);
e->bytes = le64_to_cpu(entry->bytes);
if (!e->bytes) {
kunmap(page);
kmem_cache_free(btrfs_free_space_cachep, e);
unlock_page(page);
page_cache_release(page);
goto free_cache;
}
if (entry->type == BTRFS_FREE_SPACE_EXTENT) {
spin_lock(&block_group->tree_lock);
ret = link_free_space(block_group, e);
spin_unlock(&block_group->tree_lock);
BUG_ON(ret);
} else {
e->bitmap = kzalloc(PAGE_CACHE_SIZE, GFP_NOFS);
if (!e->bitmap) {
kunmap(page);
kmem_cache_free(
btrfs_free_space_cachep, e);
unlock_page(page);
page_cache_release(page);
goto free_cache;
}
spin_lock(&block_group->tree_lock);
ret = link_free_space(block_group, e);
block_group->total_bitmaps++;
recalculate_thresholds(block_group);
spin_unlock(&block_group->tree_lock);
list_add_tail(&e->list, &bitmaps);
}
num_entries--;
offset += sizeof(struct btrfs_free_space_entry);
if (offset + sizeof(struct btrfs_free_space_entry) >=
PAGE_CACHE_SIZE)
break;
entry++;
}
/*
* We read an entry out of this page, we need to move on to the
* next page.
*/
if (need_loop) {
kunmap(page);
goto next;
}
/*
* We add the bitmaps at the end of the entries in order that
* the bitmap entries are added to the cache.
*/
e = list_entry(bitmaps.next, struct btrfs_free_space, list);
list_del_init(&e->list);
memcpy(e->bitmap, addr, PAGE_CACHE_SIZE);
kunmap(page);
num_bitmaps--;
next:
unlock_page(page);
page_cache_release(page);
index++;
}
spin_lock(&block_group->tree_lock);
if (block_group->free_space != (block_group->key.offset - used -
block_group->bytes_super)) {
spin_unlock(&block_group->tree_lock);
printk(KERN_ERR "block group %llu has an wrong amount of free "
"space\n", block_group->key.objectid);
ret = 0;
goto free_cache;
}
spin_unlock(&block_group->tree_lock);
ret = 1;
out:
kfree(checksums);
kfree(disk_crcs);
iput(inode);
return ret;
free_cache:
/* This cache is bogus, make sure it gets cleared */
spin_lock(&block_group->lock);
block_group->disk_cache_state = BTRFS_DC_CLEAR;
spin_unlock(&block_group->lock);
btrfs_remove_free_space_cache(block_group);
goto out;
}
int btrfs_write_out_cache(struct btrfs_root *root,
struct btrfs_trans_handle *trans,
struct btrfs_block_group_cache *block_group,
struct btrfs_path *path)
{
struct btrfs_free_space_header *header;
struct extent_buffer *leaf;
struct inode *inode;
struct rb_node *node;
struct list_head *pos, *n;
struct page **pages;
struct page *page;
struct extent_state *cached_state = NULL;
struct btrfs_free_cluster *cluster = NULL;
struct extent_io_tree *unpin = NULL;
struct list_head bitmap_list;
struct btrfs_key key;
u64 start, end, len;
u64 bytes = 0;
u32 *crc, *checksums;
unsigned long first_page_offset;
int index = 0, num_pages = 0;
int entries = 0;
int bitmaps = 0;
int ret = 0;
bool next_page = false;
bool out_of_space = false;
root = root->fs_info->tree_root;
INIT_LIST_HEAD(&bitmap_list);
spin_lock(&block_group->lock);
if (block_group->disk_cache_state < BTRFS_DC_SETUP) {
spin_unlock(&block_group->lock);
return 0;
}
spin_unlock(&block_group->lock);
inode = lookup_free_space_inode(root, block_group, path);
if (IS_ERR(inode))
return 0;
if (!i_size_read(inode)) {
iput(inode);
return 0;
}
node = rb_first(&block_group->free_space_offset);
if (!node) {
iput(inode);
return 0;
}
num_pages = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >>
PAGE_CACHE_SHIFT;
filemap_write_and_wait(inode->i_mapping);
btrfs_wait_ordered_range(inode, inode->i_size &
~(root->sectorsize - 1), (u64)-1);
/* We need a checksum per page. */
crc = checksums = kzalloc(sizeof(u32) * num_pages, GFP_NOFS);
if (!crc) {
iput(inode);
return 0;
}
pages = kzalloc(sizeof(struct page *) * num_pages, GFP_NOFS);
if (!pages) {
kfree(crc);
iput(inode);
return 0;
}
/* Since the first page has all of our checksums and our generation we
* need to calculate the offset into the page that we can start writing
* our entries.
*/
first_page_offset = (sizeof(u32) * num_pages) + sizeof(u64);
/* Get the cluster for this block_group if it exists */
if (!list_empty(&block_group->cluster_list))
cluster = list_entry(block_group->cluster_list.next,
struct btrfs_free_cluster,
block_group_list);
/*
* We shouldn't have switched the pinned extents yet so this is the
* right one
*/
unpin = root->fs_info->pinned_extents;
/*
* Lock all pages first so we can lock the extent safely.
*
* NOTE: Because we hold the ref the entire time we're going to write to
* the page find_get_page should never fail, so we don't do a check
* after find_get_page at this point. Just putting this here so people
* know and don't freak out.
*/
while (index < num_pages) {
page = grab_cache_page(inode->i_mapping, index);
if (!page) {
int i;
for (i = 0; i < num_pages; i++) {
unlock_page(pages[i]);
page_cache_release(pages[i]);
}
goto out_free;
}
pages[index] = page;
index++;
}
index = 0;
lock_extent_bits(&BTRFS_I(inode)->io_tree, 0, i_size_read(inode) - 1,
0, &cached_state, GFP_NOFS);
/*
* When searching for pinned extents, we need to start at our start
* offset.
*/
start = block_group->key.objectid;
/* Write out the extent entries */
do {
struct btrfs_free_space_entry *entry;
void *addr;
unsigned long offset = 0;
unsigned long start_offset = 0;
next_page = false;
if (index == 0) {
start_offset = first_page_offset;
offset = start_offset;
}
if (index >= num_pages) {
out_of_space = true;
break;
}
page = pages[index];
addr = kmap(page);
entry = addr + start_offset;
memset(addr, 0, PAGE_CACHE_SIZE);
while (node && !next_page) {
struct btrfs_free_space *e;
e = rb_entry(node, struct btrfs_free_space, offset_index);
entries++;
entry->offset = cpu_to_le64(e->offset);
entry->bytes = cpu_to_le64(e->bytes);
if (e->bitmap) {
entry->type = BTRFS_FREE_SPACE_BITMAP;
list_add_tail(&e->list, &bitmap_list);
bitmaps++;
} else {
entry->type = BTRFS_FREE_SPACE_EXTENT;
}
node = rb_next(node);
if (!node && cluster) {
node = rb_first(&cluster->root);
cluster = NULL;
}
offset += sizeof(struct btrfs_free_space_entry);
if (offset + sizeof(struct btrfs_free_space_entry) >=
PAGE_CACHE_SIZE)
next_page = true;
entry++;
}
/*
* We want to add any pinned extents to our free space cache
* so we don't leak the space
*/
while (!next_page && (start < block_group->key.objectid +
block_group->key.offset)) {
ret = find_first_extent_bit(unpin, start, &start, &end,
EXTENT_DIRTY);
if (ret) {
ret = 0;
break;
}
/* This pinned extent is out of our range */
if (start >= block_group->key.objectid +
block_group->key.offset)
break;
len = block_group->key.objectid +
block_group->key.offset - start;
len = min(len, end + 1 - start);
entries++;
entry->offset = cpu_to_le64(start);
entry->bytes = cpu_to_le64(len);
entry->type = BTRFS_FREE_SPACE_EXTENT;
start = end + 1;
offset += sizeof(struct btrfs_free_space_entry);
if (offset + sizeof(struct btrfs_free_space_entry) >=
PAGE_CACHE_SIZE)
next_page = true;
entry++;
}
*crc = ~(u32)0;
*crc = btrfs_csum_data(root, addr + start_offset, *crc,
PAGE_CACHE_SIZE - start_offset);
kunmap(page);
btrfs_csum_final(*crc, (char *)crc);
crc++;
bytes += PAGE_CACHE_SIZE;
index++;
} while (node || next_page);
/* Write out the bitmaps */
list_for_each_safe(pos, n, &bitmap_list) {
void *addr;
struct btrfs_free_space *entry =
list_entry(pos, struct btrfs_free_space, list);
if (index >= num_pages) {
out_of_space = true;
break;
}
page = pages[index];
addr = kmap(page);
memcpy(addr, entry->bitmap, PAGE_CACHE_SIZE);
*crc = ~(u32)0;
*crc = btrfs_csum_data(root, addr, *crc, PAGE_CACHE_SIZE);
kunmap(page);
btrfs_csum_final(*crc, (char *)crc);
crc++;
bytes += PAGE_CACHE_SIZE;
list_del_init(&entry->list);
index++;
}
if (out_of_space) {
btrfs_drop_pages(pages, num_pages);
unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
i_size_read(inode) - 1, &cached_state,
GFP_NOFS);
ret = 0;
goto out_free;
}
/* Zero out the rest of the pages just to make sure */
while (index < num_pages) {
void *addr;
page = pages[index];
addr = kmap(page);
memset(addr, 0, PAGE_CACHE_SIZE);
kunmap(page);
bytes += PAGE_CACHE_SIZE;
index++;
}
/* Write the checksums and trans id to the first page */
{
void *addr;
u64 *gen;
page = pages[0];
addr = kmap(page);
memcpy(addr, checksums, sizeof(u32) * num_pages);
gen = addr + (sizeof(u32) * num_pages);
*gen = trans->transid;
kunmap(page);
}
ret = btrfs_dirty_pages(root, inode, pages, num_pages, 0,
bytes, &cached_state);
btrfs_drop_pages(pages, num_pages);
unlock_extent_cached(&BTRFS_I(inode)->io_tree, 0,
i_size_read(inode) - 1, &cached_state, GFP_NOFS);
if (ret) {
ret = 0;
goto out_free;
}
BTRFS_I(inode)->generation = trans->transid;
filemap_write_and_wait(inode->i_mapping);
key.objectid = BTRFS_FREE_SPACE_OBJECTID;
key.offset = block_group->key.objectid;
key.type = 0;
ret = btrfs_search_slot(trans, root, &key, path, 1, 1);
if (ret < 0) {
ret = 0;
clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, bytes - 1,
EXTENT_DIRTY | EXTENT_DELALLOC |
EXTENT_DO_ACCOUNTING, 0, 0, NULL, GFP_NOFS);
goto out_free;
}
leaf = path->nodes[0];
if (ret > 0) {
struct btrfs_key found_key;
BUG_ON(!path->slots[0]);
path->slots[0]--;
btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
if (found_key.objectid != BTRFS_FREE_SPACE_OBJECTID ||
found_key.offset != block_group->key.objectid) {
ret = 0;
clear_extent_bit(&BTRFS_I(inode)->io_tree, 0, bytes - 1,
EXTENT_DIRTY | EXTENT_DELALLOC |
EXTENT_DO_ACCOUNTING, 0, 0, NULL,
GFP_NOFS);
btrfs_release_path(path);
goto out_free;
}
}
header = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_free_space_header);
btrfs_set_free_space_entries(leaf, header, entries);
btrfs_set_free_space_bitmaps(leaf, header, bitmaps);
btrfs_set_free_space_generation(leaf, header, trans->transid);
btrfs_mark_buffer_dirty(leaf);
btrfs_release_path(path);
ret = 1;
out_free:
if (ret == 0) {
invalidate_inode_pages2_range(inode->i_mapping, 0, index);
spin_lock(&block_group->lock);
block_group->disk_cache_state = BTRFS_DC_ERROR;
spin_unlock(&block_group->lock);
BTRFS_I(inode)->generation = 0;
}
kfree(checksums);
kfree(pages);
btrfs_update_inode(trans, root, inode);
iput(inode);
return ret;
}
static inline unsigned long offset_to_bit(u64 bitmap_start, u64 sectorsize,
u64 offset)
{
BUG_ON(offset < bitmap_start);
offset -= bitmap_start;
return (unsigned long)(div64_u64(offset, sectorsize));
}
static inline unsigned long bytes_to_bits(u64 bytes, u64 sectorsize)
{
return (unsigned long)(div64_u64(bytes, sectorsize));
}
static inline u64 offset_to_bitmap(struct btrfs_block_group_cache *block_group,
u64 offset)
{
u64 bitmap_start;
u64 bytes_per_bitmap;
bytes_per_bitmap = BITS_PER_BITMAP * block_group->sectorsize;
bitmap_start = offset - block_group->key.objectid;
bitmap_start = div64_u64(bitmap_start, bytes_per_bitmap);
bitmap_start *= bytes_per_bitmap;
bitmap_start += block_group->key.objectid;
return bitmap_start;
}
static int tree_insert_offset(struct rb_root *root, u64 offset,
struct rb_node *node, int bitmap)
{
struct rb_node **p = &root->rb_node;
struct rb_node *parent = NULL;
struct btrfs_free_space *info;
while (*p) {
parent = *p;
info = rb_entry(parent, struct btrfs_free_space, offset_index);
if (offset < info->offset) {
p = &(*p)->rb_left;
} else if (offset > info->offset) {
p = &(*p)->rb_right;
} else {
/*
* we could have a bitmap entry and an extent entry
* share the same offset. If this is the case, we want
* the extent entry to always be found first if we do a
* linear search through the tree, since we want to have
* the quickest allocation time, and allocating from an
* extent is faster than allocating from a bitmap. So
* if we're inserting a bitmap and we find an entry at
* this offset, we want to go right, or after this entry
* logically. If we are inserting an extent and we've
* found a bitmap, we want to go left, or before
* logically.
*/
if (bitmap) {
WARN_ON(info->bitmap);
p = &(*p)->rb_right;
} else {
WARN_ON(!info->bitmap);
p = &(*p)->rb_left;
}
}
}
rb_link_node(node, parent, p);
rb_insert_color(node, root);
return 0;
}
/*
* searches the tree for the given offset.
*
* fuzzy - If this is set, then we are trying to make an allocation, and we just
* want a section that has at least bytes size and comes at or after the given
* offset.
*/
static struct btrfs_free_space *
tree_search_offset(struct btrfs_block_group_cache *block_group,
u64 offset, int bitmap_only, int fuzzy)
{
struct rb_node *n = block_group->free_space_offset.rb_node;
struct btrfs_free_space *entry, *prev = NULL;
/* find entry that is closest to the 'offset' */
while (1) {
if (!n) {
entry = NULL;
break;
}
entry = rb_entry(n, struct btrfs_free_space, offset_index);
prev = entry;
if (offset < entry->offset)
n = n->rb_left;
else if (offset > entry->offset)
n = n->rb_right;
else
break;
}
if (bitmap_only) {
if (!entry)
return NULL;
if (entry->bitmap)
return entry;
/*
* bitmap entry and extent entry may share same offset,
* in that case, bitmap entry comes after extent entry.
*/
n = rb_next(n);
if (!n)
return NULL;
entry = rb_entry(n, struct btrfs_free_space, offset_index);
if (entry->offset != offset)
return NULL;
WARN_ON(!entry->bitmap);
return entry;
} else if (entry) {
if (entry->bitmap) {
/*
* if previous extent entry covers the offset,
* we should return it instead of the bitmap entry
*/
n = &entry->offset_index;
while (1) {
n = rb_prev(n);
if (!n)
break;
prev = rb_entry(n, struct btrfs_free_space,
offset_index);
if (!prev->bitmap) {
if (prev->offset + prev->bytes > offset)
entry = prev;
break;
}
}
}
return entry;
}
if (!prev)
return NULL;
/* find last entry before the 'offset' */
entry = prev;
if (entry->offset > offset) {
n = rb_prev(&entry->offset_index);
if (n) {
entry = rb_entry(n, struct btrfs_free_space,
offset_index);
BUG_ON(entry->offset > offset);
} else {
if (fuzzy)
return entry;
else
return NULL;
}
}
if (entry->bitmap) {
n = &entry->offset_index;
while (1) {
n = rb_prev(n);
if (!n)
break;
prev = rb_entry(n, struct btrfs_free_space,
offset_index);
if (!prev->bitmap) {
if (prev->offset + prev->bytes > offset)
return prev;
break;
}
}
if (entry->offset + BITS_PER_BITMAP *
block_group->sectorsize > offset)
return entry;
} else if (entry->offset + entry->bytes > offset)
return entry;
if (!fuzzy)
return NULL;
while (1) {
if (entry->bitmap) {
if (entry->offset + BITS_PER_BITMAP *
block_group->sectorsize > offset)
break;
} else {
if (entry->offset + entry->bytes > offset)
break;
}
n = rb_next(&entry->offset_index);
if (!n)
return NULL;
entry = rb_entry(n, struct btrfs_free_space, offset_index);
}
return entry;
}
static inline void
__unlink_free_space(struct btrfs_block_group_cache *block_group,
struct btrfs_free_space *info)
{
rb_erase(&info->offset_index, &block_group->free_space_offset);
block_group->free_extents--;
}
static void unlink_free_space(struct btrfs_block_group_cache *block_group,
struct btrfs_free_space *info)
{
__unlink_free_space(block_group, info);
block_group->free_space -= info->bytes;
}
static int link_free_space(struct btrfs_block_group_cache *block_group,
struct btrfs_free_space *info)
{
int ret = 0;
BUG_ON(!info->bitmap && !info->bytes);
ret = tree_insert_offset(&block_group->free_space_offset, info->offset,
&info->offset_index, (info->bitmap != NULL));
if (ret)
return ret;
block_group->free_space += info->bytes;
block_group->free_extents++;
return ret;
}
static void recalculate_thresholds(struct btrfs_block_group_cache *block_group)
{
u64 max_bytes;
u64 bitmap_bytes;
u64 extent_bytes;
u64 size = block_group->key.offset;
/*
* The goal is to keep the total amount of memory used per 1gb of space
* at or below 32k, so we need to adjust how much memory we allow to be
* used by extent based free space tracking
*/
if (size < 1024 * 1024 * 1024)
max_bytes = MAX_CACHE_BYTES_PER_GIG;
else
max_bytes = MAX_CACHE_BYTES_PER_GIG *
div64_u64(size, 1024 * 1024 * 1024);
/*
* we want to account for 1 more bitmap than what we have so we can make
* sure we don't go over our overall goal of MAX_CACHE_BYTES_PER_GIG as
* we add more bitmaps.
*/
bitmap_bytes = (block_group->total_bitmaps + 1) * PAGE_CACHE_SIZE;
if (bitmap_bytes >= max_bytes) {
block_group->extents_thresh = 0;
return;
}
/*
* we want the extent entry threshold to always be at most 1/2 the maxw
* bytes we can have, or whatever is less than that.
*/
extent_bytes = max_bytes - bitmap_bytes;
extent_bytes = min_t(u64, extent_bytes, div64_u64(max_bytes, 2));
block_group->extents_thresh =
div64_u64(extent_bytes, (sizeof(struct btrfs_free_space)));
}
static void bitmap_clear_bits(struct btrfs_block_group_cache *block_group,
struct btrfs_free_space *info, u64 offset,
u64 bytes)
{
unsigned long start, end;
unsigned long i;
start = offset_to_bit(info->offset, block_group->sectorsize, offset);
end = start + bytes_to_bits(bytes, block_group->sectorsize);
BUG_ON(end > BITS_PER_BITMAP);
for (i = start; i < end; i++)
clear_bit(i, info->bitmap);
info->bytes -= bytes;
block_group->free_space -= bytes;
}
static void bitmap_set_bits(struct btrfs_block_group_cache *block_group,
struct btrfs_free_space *info, u64 offset,
u64 bytes)
{
unsigned long start, end;
unsigned long i;
start = offset_to_bit(info->offset, block_group->sectorsize, offset);
end = start + bytes_to_bits(bytes, block_group->sectorsize);
BUG_ON(end > BITS_PER_BITMAP);
for (i = start; i < end; i++)
set_bit(i, info->bitmap);
info->bytes += bytes;
block_group->free_space += bytes;
}
static int search_bitmap(struct btrfs_block_group_cache *block_group,
struct btrfs_free_space *bitmap_info, u64 *offset,
u64 *bytes)
{
unsigned long found_bits = 0;
unsigned long bits, i;
unsigned long next_zero;
i = offset_to_bit(bitmap_info->offset, block_group->sectorsize,
max_t(u64, *offset, bitmap_info->offset));
bits = bytes_to_bits(*bytes, block_group->sectorsize);
for (i = find_next_bit(bitmap_info->bitmap, BITS_PER_BITMAP, i);
i < BITS_PER_BITMAP;
i = find_next_bit(bitmap_info->bitmap, BITS_PER_BITMAP, i + 1)) {
next_zero = find_next_zero_bit(bitmap_info->bitmap,
BITS_PER_BITMAP, i);
if ((next_zero - i) >= bits) {
found_bits = next_zero - i;
break;
}
i = next_zero;
}
if (found_bits) {
*offset = (u64)(i * block_group->sectorsize) +
bitmap_info->offset;
*bytes = (u64)(found_bits) * block_group->sectorsize;
return 0;
}
return -1;
}
static struct btrfs_free_space *find_free_space(struct btrfs_block_group_cache
*block_group, u64 *offset,
u64 *bytes, int debug)
{
struct btrfs_free_space *entry;
struct rb_node *node;
int ret;
if (!block_group->free_space_offset.rb_node)
return NULL;
entry = tree_search_offset(block_group,
offset_to_bitmap(block_group, *offset),
0, 1);
if (!entry)
return NULL;
for (node = &entry->offset_index; node; node = rb_next(node)) {
entry = rb_entry(node, struct btrfs_free_space, offset_index);
if (entry->bytes < *bytes)
continue;
if (entry->bitmap) {
ret = search_bitmap(block_group, entry, offset, bytes);
if (!ret)
return entry;
continue;
}
*offset = entry->offset;
*bytes = entry->bytes;
return entry;
}
return NULL;
}
static void add_new_bitmap(struct btrfs_block_group_cache *block_group,
struct btrfs_free_space *info, u64 offset)
{
u64 bytes_per_bg = BITS_PER_BITMAP * block_group->sectorsize;
int max_bitmaps = (int)div64_u64(block_group->key.offset +
bytes_per_bg - 1, bytes_per_bg);
BUG_ON(block_group->total_bitmaps >= max_bitmaps);
info->offset = offset_to_bitmap(block_group, offset);
info->bytes = 0;
link_free_space(block_group, info);
block_group->total_bitmaps++;
recalculate_thresholds(block_group);
}
static void free_bitmap(struct btrfs_block_group_cache *block_group,
struct btrfs_free_space *bitmap_info)
{
unlink_free_space(block_group, bitmap_info);
kfree(bitmap_info->bitmap);
kmem_cache_free(btrfs_free_space_cachep, bitmap_info);
block_group->total_bitmaps--;
recalculate_thresholds(block_group);
}
static noinline int remove_from_bitmap(struct btrfs_block_group_cache *block_group,
struct btrfs_free_space *bitmap_info,
u64 *offset, u64 *bytes)
{
u64 end;
u64 search_start, search_bytes;
int ret;
again:
end = bitmap_info->offset +
(u64)(BITS_PER_BITMAP * block_group->sectorsize) - 1;
/*
* XXX - this can go away after a few releases.
*
* since the only user of btrfs_remove_free_space is the tree logging
* stuff, and the only way to test that is under crash conditions, we
* want to have this debug stuff here just in case somethings not
* working. Search the bitmap for the space we are trying to use to
* make sure its actually there. If its not there then we need to stop
* because something has gone wrong.
*/
search_start = *offset;
search_bytes = *bytes;
search_bytes = min(search_bytes, end - search_start + 1);
ret = search_bitmap(block_group, bitmap_info, &search_start,
&search_bytes);
BUG_ON(ret < 0 || search_start != *offset);
if (*offset > bitmap_info->offset && *offset + *bytes > end) {
bitmap_clear_bits(block_group, bitmap_info, *offset,
end - *offset + 1);
*bytes -= end - *offset + 1;
*offset = end + 1;
} else if (*offset >= bitmap_info->offset && *offset + *bytes <= end) {
bitmap_clear_bits(block_group, bitmap_info, *offset, *bytes);
*bytes = 0;
}
if (*bytes) {
struct rb_node *next = rb_next(&bitmap_info->offset_index);
if (!bitmap_info->bytes)
free_bitmap(block_group, bitmap_info);
/*
* no entry after this bitmap, but we still have bytes to
* remove, so something has gone wrong.
*/
if (!next)
return -EINVAL;
bitmap_info = rb_entry(next, struct btrfs_free_space,
offset_index);
/*
* if the next entry isn't a bitmap we need to return to let the
* extent stuff do its work.
*/
if (!bitmap_info->bitmap)
return -EAGAIN;
/*
* Ok the next item is a bitmap, but it may not actually hold
* the information for the rest of this free space stuff, so
* look for it, and if we don't find it return so we can try
* everything over again.
*/
search_start = *offset;
search_bytes = *bytes;
ret = search_bitmap(block_group, bitmap_info, &search_start,
&search_bytes);
if (ret < 0 || search_start != *offset)
return -EAGAIN;
goto again;
} else if (!bitmap_info->bytes)
free_bitmap(block_group, bitmap_info);
return 0;
}
static int insert_into_bitmap(struct btrfs_block_group_cache *block_group,
struct btrfs_free_space *info)
{
struct btrfs_free_space *bitmap_info;
int added = 0;
u64 bytes, offset, end;
int ret;
/*
* If we are below the extents threshold then we can add this as an
* extent, and don't have to deal with the bitmap
*/
if (block_group->free_extents < block_group->extents_thresh) {
/*
* If this block group has some small extents we don't want to
* use up all of our free slots in the cache with them, we want
* to reserve them to larger extents, however if we have plent
* of cache left then go ahead an dadd them, no sense in adding
* the overhead of a bitmap if we don't have to.
*/
if (info->bytes <= block_group->sectorsize * 4) {
if (block_group->free_extents * 2 <=
block_group->extents_thresh)
return 0;
} else {
return 0;
}
}
/*
* some block groups are so tiny they can't be enveloped by a bitmap, so
* don't even bother to create a bitmap for this
*/
if (BITS_PER_BITMAP * block_group->sectorsize >
block_group->key.offset)
return 0;
bytes = info->bytes;
offset = info->offset;
again:
bitmap_info = tree_search_offset(block_group,
offset_to_bitmap(block_group, offset),
1, 0);
if (!bitmap_info) {
BUG_ON(added);
goto new_bitmap;
}
end = bitmap_info->offset +
(u64)(BITS_PER_BITMAP * block_group->sectorsize);
if (offset >= bitmap_info->offset && offset + bytes > end) {
bitmap_set_bits(block_group, bitmap_info, offset,
end - offset);
bytes -= end - offset;
offset = end;
added = 0;
} else if (offset >= bitmap_info->offset && offset + bytes <= end) {
bitmap_set_bits(block_group, bitmap_info, offset, bytes);
bytes = 0;
} else {
BUG();
}
if (!bytes) {
ret = 1;
goto out;
} else
goto again;
new_bitmap:
if (info && info->bitmap) {
add_new_bitmap(block_group, info, offset);
added = 1;
info = NULL;
goto again;
} else {
spin_unlock(&block_group->tree_lock);
/* no pre-allocated info, allocate a new one */
if (!info) {
info = kmem_cache_zalloc(btrfs_free_space_cachep,
GFP_NOFS);
if (!info) {
spin_lock(&block_group->tree_lock);
ret = -ENOMEM;
goto out;
}
}
/* allocate the bitmap */
info->bitmap = kzalloc(PAGE_CACHE_SIZE, GFP_NOFS);
spin_lock(&block_group->tree_lock);
if (!info->bitmap) {
ret = -ENOMEM;
goto out;
}
goto again;
}
out:
if (info) {
if (info->bitmap)
kfree(info->bitmap);
kmem_cache_free(btrfs_free_space_cachep, info);
}
return ret;
}
static bool try_merge_free_space(struct btrfs_block_group_cache *block_group,
struct btrfs_free_space *info, bool update_stat)
{
struct btrfs_free_space *left_info;
struct btrfs_free_space *right_info;
bool merged = false;
u64 offset = info->offset;
u64 bytes = info->bytes;
/*
* first we want to see if there is free space adjacent to the range we
* are adding, if there is remove that struct and add a new one to
* cover the entire range
*/
right_info = tree_search_offset(block_group, offset + bytes, 0, 0);
if (right_info && rb_prev(&right_info->offset_index))
left_info = rb_entry(rb_prev(&right_info->offset_index),
struct btrfs_free_space, offset_index);
else
left_info = tree_search_offset(block_group, offset - 1, 0, 0);
if (right_info && !right_info->bitmap) {
if (update_stat)
unlink_free_space(block_group, right_info);
else
__unlink_free_space(block_group, right_info);
info->bytes += right_info->bytes;
kmem_cache_free(btrfs_free_space_cachep, right_info);
merged = true;
}
if (left_info && !left_info->bitmap &&
left_info->offset + left_info->bytes == offset) {
if (update_stat)
unlink_free_space(block_group, left_info);
else
__unlink_free_space(block_group, left_info);
info->offset = left_info->offset;
info->bytes += left_info->bytes;
kmem_cache_free(btrfs_free_space_cachep, left_info);
merged = true;
}
return merged;
}
int btrfs_add_free_space(struct btrfs_block_group_cache *block_group,
u64 offset, u64 bytes)
{
struct btrfs_free_space *info;
int ret = 0;
info = kmem_cache_zalloc(btrfs_free_space_cachep, GFP_NOFS);
if (!info)
return -ENOMEM;
info->offset = offset;
info->bytes = bytes;
spin_lock(&block_group->tree_lock);
if (try_merge_free_space(block_group, info, true))
goto link;
/*
* There was no extent directly to the left or right of this new
* extent then we know we're going to have to allocate a new extent, so
* before we do that see if we need to drop this into a bitmap
*/
ret = insert_into_bitmap(block_group, info);
if (ret < 0) {
goto out;
} else if (ret) {
ret = 0;
goto out;
}
link:
ret = link_free_space(block_group, info);
if (ret)
kmem_cache_free(btrfs_free_space_cachep, info);
out:
spin_unlock(&block_group->tree_lock);
if (ret) {
printk(KERN_CRIT "btrfs: unable to add free space :%d\n", ret);
BUG_ON(ret == -EEXIST);
}
return ret;
}
int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group,
u64 offset, u64 bytes)
{
struct btrfs_free_space *info;
struct btrfs_free_space *next_info = NULL;
int ret = 0;
spin_lock(&block_group->tree_lock);
again:
info = tree_search_offset(block_group, offset, 0, 0);
if (!info) {
/*
* oops didn't find an extent that matched the space we wanted
* to remove, look for a bitmap instead
*/
info = tree_search_offset(block_group,
offset_to_bitmap(block_group, offset),
1, 0);
if (!info) {
WARN_ON(1);
goto out_lock;
}
}
if (info->bytes < bytes && rb_next(&info->offset_index)) {
u64 end;
next_info = rb_entry(rb_next(&info->offset_index),
struct btrfs_free_space,
offset_index);
if (next_info->bitmap)
end = next_info->offset + BITS_PER_BITMAP *
block_group->sectorsize - 1;
else
end = next_info->offset + next_info->bytes;
if (next_info->bytes < bytes ||
next_info->offset > offset || offset > end) {
printk(KERN_CRIT "Found free space at %llu, size %llu,"
" trying to use %llu\n",
(unsigned long long)info->offset,
(unsigned long long)info->bytes,
(unsigned long long)bytes);
WARN_ON(1);
ret = -EINVAL;
goto out_lock;
}
info = next_info;
}
if (info->bytes == bytes) {
unlink_free_space(block_group, info);
if (info->bitmap) {
kfree(info->bitmap);
block_group->total_bitmaps--;
}
kmem_cache_free(btrfs_free_space_cachep, info);
goto out_lock;
}
if (!info->bitmap && info->offset == offset) {
unlink_free_space(block_group, info);
info->offset += bytes;
info->bytes -= bytes;
link_free_space(block_group, info);
goto out_lock;
}
if (!info->bitmap && info->offset <= offset &&
info->offset + info->bytes >= offset + bytes) {
u64 old_start = info->offset;
/*
* we're freeing space in the middle of the info,
* this can happen during tree log replay
*
* first unlink the old info and then
* insert it again after the hole we're creating
*/
unlink_free_space(block_group, info);
if (offset + bytes < info->offset + info->bytes) {
u64 old_end = info->offset + info->bytes;
info->offset = offset + bytes;
info->bytes = old_end - info->offset;
ret = link_free_space(block_group, info);
WARN_ON(ret);
if (ret)
goto out_lock;
} else {
/* the hole we're creating ends at the end
* of the info struct, just free the info
*/
kmem_cache_free(btrfs_free_space_cachep, info);
}
spin_unlock(&block_group->tree_lock);
/* step two, insert a new info struct to cover
* anything before the hole
*/
ret = btrfs_add_free_space(block_group, old_start,
offset - old_start);
WARN_ON(ret);
goto out;
}
ret = remove_from_bitmap(block_group, info, &offset, &bytes);
if (ret == -EAGAIN)
goto again;
BUG_ON(ret);
out_lock:
spin_unlock(&block_group->tree_lock);
out:
return ret;
}
void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group,
u64 bytes)
{
struct btrfs_free_space *info;
struct rb_node *n;
int count = 0;
for (n = rb_first(&block_group->free_space_offset); n; n = rb_next(n)) {
info = rb_entry(n, struct btrfs_free_space, offset_index);
if (info->bytes >= bytes)
count++;
printk(KERN_CRIT "entry offset %llu, bytes %llu, bitmap %s\n",
(unsigned long long)info->offset,
(unsigned long long)info->bytes,
(info->bitmap) ? "yes" : "no");
}
printk(KERN_INFO "block group has cluster?: %s\n",
list_empty(&block_group->cluster_list) ? "no" : "yes");
printk(KERN_INFO "%d blocks of free space at or bigger than bytes is"
"\n", count);
}
/*
* for a given cluster, put all of its extents back into the free
* space cache. If the block group passed doesn't match the block group
* pointed to by the cluster, someone else raced in and freed the
* cluster already. In that case, we just return without changing anything
*/
static int
__btrfs_return_cluster_to_free_space(
struct btrfs_block_group_cache *block_group,
struct btrfs_free_cluster *cluster)
{
struct btrfs_free_space *entry;
struct rb_node *node;
spin_lock(&cluster->lock);
if (cluster->block_group != block_group)
goto out;
cluster->block_group = NULL;
cluster->window_start = 0;
list_del_init(&cluster->block_group_list);
node = rb_first(&cluster->root);
while (node) {
bool bitmap;
entry = rb_entry(node, struct btrfs_free_space, offset_index);
node = rb_next(&entry->offset_index);
rb_erase(&entry->offset_index, &cluster->root);
bitmap = (entry->bitmap != NULL);
if (!bitmap)
try_merge_free_space(block_group, entry, false);
tree_insert_offset(&block_group->free_space_offset,
entry->offset, &entry->offset_index, bitmap);
}
cluster->root = RB_ROOT;
out:
spin_unlock(&cluster->lock);
btrfs_put_block_group(block_group);
return 0;
}
void btrfs_remove_free_space_cache(struct btrfs_block_group_cache *block_group)
{
struct btrfs_free_space *info;
struct rb_node *node;
struct btrfs_free_cluster *cluster;
struct list_head *head;
spin_lock(&block_group->tree_lock);
while ((head = block_group->cluster_list.next) !=
&block_group->cluster_list) {
cluster = list_entry(head, struct btrfs_free_cluster,
block_group_list);
WARN_ON(cluster->block_group != block_group);
__btrfs_return_cluster_to_free_space(block_group, cluster);
if (need_resched()) {
spin_unlock(&block_group->tree_lock);
cond_resched();
spin_lock(&block_group->tree_lock);
}
}
while ((node = rb_last(&block_group->free_space_offset)) != NULL) {
info = rb_entry(node, struct btrfs_free_space, offset_index);
if (!info->bitmap) {
unlink_free_space(block_group, info);
kmem_cache_free(btrfs_free_space_cachep, info);
} else {
free_bitmap(block_group, info);
}
if (need_resched()) {
spin_unlock(&block_group->tree_lock);
cond_resched();
spin_lock(&block_group->tree_lock);
}
}
spin_unlock(&block_group->tree_lock);
}
u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group,
u64 offset, u64 bytes, u64 empty_size)
{
struct btrfs_free_space *entry = NULL;
u64 bytes_search = bytes + empty_size;
u64 ret = 0;
spin_lock(&block_group->tree_lock);
entry = find_free_space(block_group, &offset, &bytes_search, 0);
if (!entry)
goto out;
ret = offset;
if (entry->bitmap) {
bitmap_clear_bits(block_group, entry, offset, bytes);
if (!entry->bytes)
free_bitmap(block_group, entry);
} else {
unlink_free_space(block_group, entry);
entry->offset += bytes;
entry->bytes -= bytes;
if (!entry->bytes)
kmem_cache_free(btrfs_free_space_cachep, entry);
else
link_free_space(block_group, entry);
}
out:
spin_unlock(&block_group->tree_lock);
return ret;
}
/*
* given a cluster, put all of its extents back into the free space
* cache. If a block group is passed, this function will only free
* a cluster that belongs to the passed block group.
*
* Otherwise, it'll get a reference on the block group pointed to by the
* cluster and remove the cluster from it.
*/
int btrfs_return_cluster_to_free_space(
struct btrfs_block_group_cache *block_group,
struct btrfs_free_cluster *cluster)
{
int ret;
/* first, get a safe pointer to the block group */
spin_lock(&cluster->lock);
if (!block_group) {
block_group = cluster->block_group;
if (!block_group) {
spin_unlock(&cluster->lock);
return 0;
}
} else if (cluster->block_group != block_group) {
/* someone else has already freed it don't redo their work */
spin_unlock(&cluster->lock);
return 0;
}
atomic_inc(&block_group->count);
spin_unlock(&cluster->lock);
/* now return any extents the cluster had on it */
spin_lock(&block_group->tree_lock);
ret = __btrfs_return_cluster_to_free_space(block_group, cluster);
spin_unlock(&block_group->tree_lock);
/* finally drop our ref */
btrfs_put_block_group(block_group);
return ret;
}
static u64 btrfs_alloc_from_bitmap(struct btrfs_block_group_cache *block_group,
struct btrfs_free_cluster *cluster,
struct btrfs_free_space *entry,
u64 bytes, u64 min_start)
{
int err;
u64 search_start = cluster->window_start;
u64 search_bytes = bytes;
u64 ret = 0;
search_start = min_start;
search_bytes = bytes;
err = search_bitmap(block_group, entry, &search_start,
&search_bytes);
if (err)
return 0;
ret = search_start;
bitmap_clear_bits(block_group, entry, ret, bytes);
return ret;
}
/*
* given a cluster, try to allocate 'bytes' from it, returns 0
* if it couldn't find anything suitably large, or a logical disk offset
* if things worked out
*/
u64 btrfs_alloc_from_cluster(struct btrfs_block_group_cache *block_group,
struct btrfs_free_cluster *cluster, u64 bytes,
u64 min_start)
{
struct btrfs_free_space *entry = NULL;
struct rb_node *node;
u64 ret = 0;
spin_lock(&cluster->lock);
if (bytes > cluster->max_size)
goto out;
if (cluster->block_group != block_group)
goto out;
node = rb_first(&cluster->root);
if (!node)
goto out;
entry = rb_entry(node, struct btrfs_free_space, offset_index);
while(1) {
if (entry->bytes < bytes ||
(!entry->bitmap && entry->offset < min_start)) {
node = rb_next(&entry->offset_index);
if (!node)
break;
entry = rb_entry(node, struct btrfs_free_space,
offset_index);
continue;
}
if (entry->bitmap) {
ret = btrfs_alloc_from_bitmap(block_group,
cluster, entry, bytes,
min_start);
if (ret == 0) {
node = rb_next(&entry->offset_index);
if (!node)
break;
entry = rb_entry(node, struct btrfs_free_space,
offset_index);
continue;
}
} else {
ret = entry->offset;
entry->offset += bytes;
entry->bytes -= bytes;
}
if (entry->bytes == 0)
rb_erase(&entry->offset_index, &cluster->root);
break;
}
out:
spin_unlock(&cluster->lock);
if (!ret)
return 0;
spin_lock(&block_group->tree_lock);
block_group->free_space -= bytes;
if (entry->bytes == 0) {
block_group->free_extents--;
if (entry->bitmap) {
kfree(entry->bitmap);
block_group->total_bitmaps--;
recalculate_thresholds(block_group);
}
kmem_cache_free(btrfs_free_space_cachep, entry);
}
spin_unlock(&block_group->tree_lock);
return ret;
}
static int btrfs_bitmap_cluster(struct btrfs_block_group_cache *block_group,
struct btrfs_free_space *entry,
struct btrfs_free_cluster *cluster,
u64 offset, u64 bytes, u64 min_bytes)
{
unsigned long next_zero;
unsigned long i;
unsigned long search_bits;
unsigned long total_bits;
unsigned long found_bits;
unsigned long start = 0;
unsigned long total_found = 0;
int ret;
bool found = false;
i = offset_to_bit(entry->offset, block_group->sectorsize,
max_t(u64, offset, entry->offset));
search_bits = bytes_to_bits(bytes, block_group->sectorsize);
total_bits = bytes_to_bits(min_bytes, block_group->sectorsize);
again:
found_bits = 0;
for (i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, i);
i < BITS_PER_BITMAP;
i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, i + 1)) {
next_zero = find_next_zero_bit(entry->bitmap,
BITS_PER_BITMAP, i);
if (next_zero - i >= search_bits) {
found_bits = next_zero - i;
break;
}
i = next_zero;
}
if (!found_bits)
return -ENOSPC;
if (!found) {
start = i;
found = true;
}
total_found += found_bits;
if (cluster->max_size < found_bits * block_group->sectorsize)
cluster->max_size = found_bits * block_group->sectorsize;
if (total_found < total_bits) {
i = find_next_bit(entry->bitmap, BITS_PER_BITMAP, next_zero);
if (i - start > total_bits * 2) {
total_found = 0;
cluster->max_size = 0;
found = false;
}
goto again;
}
cluster->window_start = start * block_group->sectorsize +
entry->offset;
rb_erase(&entry->offset_index, &block_group->free_space_offset);
ret = tree_insert_offset(&cluster->root, entry->offset,
&entry->offset_index, 1);
BUG_ON(ret);
return 0;
}
/*
* This searches the block group for just extents to fill the cluster with.
*/
static int setup_cluster_no_bitmap(struct btrfs_block_group_cache *block_group,
struct btrfs_free_cluster *cluster,
u64 offset, u64 bytes, u64 min_bytes)
{
struct btrfs_free_space *first = NULL;
struct btrfs_free_space *entry = NULL;
struct btrfs_free_space *prev = NULL;
struct btrfs_free_space *last;
struct rb_node *node;
u64 window_start;
u64 window_free;
u64 max_extent;
u64 max_gap = 128 * 1024;
entry = tree_search_offset(block_group, offset, 0, 1);
if (!entry)
return -ENOSPC;
/*
* We don't want bitmaps, so just move along until we find a normal
* extent entry.
*/
while (entry->bitmap) {
node = rb_next(&entry->offset_index);
if (!node)
return -ENOSPC;
entry = rb_entry(node, struct btrfs_free_space, offset_index);
}
window_start = entry->offset;
window_free = entry->bytes;
max_extent = entry->bytes;
first = entry;
last = entry;
prev = entry;
while (window_free <= min_bytes) {
node = rb_next(&entry->offset_index);
if (!node)
return -ENOSPC;
entry = rb_entry(node, struct btrfs_free_space, offset_index);
if (entry->bitmap)
continue;
/*
* we haven't filled the empty size and the window is
* very large. reset and try again
*/
if (entry->offset - (prev->offset + prev->bytes) > max_gap ||
entry->offset - window_start > (min_bytes * 2)) {
first = entry;
window_start = entry->offset;
window_free = entry->bytes;
last = entry;
max_extent = entry->bytes;
} else {
last = entry;
window_free += entry->bytes;
if (entry->bytes > max_extent)
max_extent = entry->bytes;
}
prev = entry;
}
cluster->window_start = first->offset;
node = &first->offset_index;
/*
* now we've found our entries, pull them out of the free space
* cache and put them into the cluster rbtree
*/
do {
int ret;
entry = rb_entry(node, struct btrfs_free_space, offset_index);
node = rb_next(&entry->offset_index);
if (entry->bitmap)
continue;
rb_erase(&entry->offset_index, &block_group->free_space_offset);
ret = tree_insert_offset(&cluster->root, entry->offset,
&entry->offset_index, 0);
BUG_ON(ret);
} while (node && entry != last);
cluster->max_size = max_extent;
return 0;
}
/*
* This specifically looks for bitmaps that may work in the cluster, we assume
* that we have already failed to find extents that will work.
*/
static int setup_cluster_bitmap(struct btrfs_block_group_cache *block_group,
struct btrfs_free_cluster *cluster,
u64 offset, u64 bytes, u64 min_bytes)
{
struct btrfs_free_space *entry;
struct rb_node *node;
int ret = -ENOSPC;
if (block_group->total_bitmaps == 0)
return -ENOSPC;
entry = tree_search_offset(block_group,
offset_to_bitmap(block_group, offset),
0, 1);
if (!entry)
return -ENOSPC;
node = &entry->offset_index;
do {
entry = rb_entry(node, struct btrfs_free_space, offset_index);
node = rb_next(&entry->offset_index);
if (!entry->bitmap)
continue;
if (entry->bytes < min_bytes)
continue;
ret = btrfs_bitmap_cluster(block_group, entry, cluster, offset,
bytes, min_bytes);
} while (ret && node);
return ret;
}
/*
* here we try to find a cluster of blocks in a block group. The goal
* is to find at least bytes free and up to empty_size + bytes free.
* We might not find them all in one contiguous area.
*
* returns zero and sets up cluster if things worked out, otherwise
* it returns -enospc
*/
int btrfs_find_space_cluster(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct btrfs_block_group_cache *block_group,
struct btrfs_free_cluster *cluster,
u64 offset, u64 bytes, u64 empty_size)
{
u64 min_bytes;
int ret;
/* for metadata, allow allocates with more holes */
if (btrfs_test_opt(root, SSD_SPREAD)) {
min_bytes = bytes + empty_size;
} else if (block_group->flags & BTRFS_BLOCK_GROUP_METADATA) {
/*
* we want to do larger allocations when we are
* flushing out the delayed refs, it helps prevent
* making more work as we go along.
*/
if (trans->transaction->delayed_refs.flushing)
min_bytes = max(bytes, (bytes + empty_size) >> 1);
else
min_bytes = max(bytes, (bytes + empty_size) >> 4);
} else
min_bytes = max(bytes, (bytes + empty_size) >> 2);
spin_lock(&block_group->tree_lock);
/*
* If we know we don't have enough space to make a cluster don't even
* bother doing all the work to try and find one.
*/
if (block_group->free_space < min_bytes) {
spin_unlock(&block_group->tree_lock);
return -ENOSPC;
}
spin_lock(&cluster->lock);
/* someone already found a cluster, hooray */
if (cluster->block_group) {
ret = 0;
goto out;
}
ret = setup_cluster_no_bitmap(block_group, cluster, offset, bytes,
min_bytes);
if (ret)
ret = setup_cluster_bitmap(block_group, cluster, offset,
bytes, min_bytes);
if (!ret) {
atomic_inc(&block_group->count);
list_add_tail(&cluster->block_group_list,
&block_group->cluster_list);
cluster->block_group = block_group;
}
out:
spin_unlock(&cluster->lock);
spin_unlock(&block_group->tree_lock);
return ret;
}
/*
* simple code to zero out a cluster
*/
void btrfs_init_free_cluster(struct btrfs_free_cluster *cluster)
{
spin_lock_init(&cluster->lock);
spin_lock_init(&cluster->refill_lock);
cluster->root = RB_ROOT;
cluster->max_size = 0;
INIT_LIST_HEAD(&cluster->block_group_list);
cluster->block_group = NULL;
}
int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,
u64 *trimmed, u64 start, u64 end, u64 minlen)
{
struct btrfs_free_space *entry = NULL;
struct btrfs_fs_info *fs_info = block_group->fs_info;
u64 bytes = 0;
u64 actually_trimmed;
int ret = 0;
*trimmed = 0;
while (start < end) {
spin_lock(&block_group->tree_lock);
if (block_group->free_space < minlen) {
spin_unlock(&block_group->tree_lock);
break;
}
entry = tree_search_offset(block_group, start, 0, 1);
if (!entry)
entry = tree_search_offset(block_group,
offset_to_bitmap(block_group,
start),
1, 1);
if (!entry || entry->offset >= end) {
spin_unlock(&block_group->tree_lock);
break;
}
if (entry->bitmap) {
ret = search_bitmap(block_group, entry, &start, &bytes);
if (!ret) {
if (start >= end) {
spin_unlock(&block_group->tree_lock);
break;
}
bytes = min(bytes, end - start);
bitmap_clear_bits(block_group, entry,
start, bytes);
if (entry->bytes == 0)
free_bitmap(block_group, entry);
} else {
start = entry->offset + BITS_PER_BITMAP *
block_group->sectorsize;
spin_unlock(&block_group->tree_lock);
ret = 0;
continue;
}
} else {
start = entry->offset;
bytes = min(entry->bytes, end - start);
unlink_free_space(block_group, entry);
kmem_cache_free(btrfs_free_space_cachep, entry);
}
spin_unlock(&block_group->tree_lock);
if (bytes >= minlen) {
int update_ret;
update_ret = btrfs_update_reserved_bytes(block_group,
bytes, 1, 1);
ret = btrfs_error_discard_extent(fs_info->extent_root,
start,
bytes,
&actually_trimmed);
btrfs_add_free_space(block_group,
start, bytes);
if (!update_ret)
btrfs_update_reserved_bytes(block_group,
bytes, 0, 1);
if (ret)
break;
*trimmed += actually_trimmed;
}
start += bytes;
bytes = 0;
if (fatal_signal_pending(current)) {
ret = -ERESTARTSYS;
break;
}
cond_resched();
}
return ret;
}
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