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

1366 lines
34 KiB
C

/*
* 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"
#define BITS_PER_BITMAP (PAGE_CACHE_SIZE * 8)
#define MAX_CACHE_BYTES_PER_GIG (32 * 1024)
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 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--;
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;
/*
* 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
*/
max_bytes = MAX_CACHE_BYTES_PER_GIG *
(div64_u64(block_group->key.offset, 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 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;
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) {
unlink_free_space(block_group, bitmap_info);
kfree(bitmap_info->bitmap);
kfree(bitmap_info);
block_group->total_bitmaps--;
recalculate_thresholds(block_group);
}
/*
* 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) {
unlink_free_space(block_group, bitmap_info);
kfree(bitmap_info->bitmap);
kfree(bitmap_info);
block_group->total_bitmaps--;
recalculate_thresholds(block_group);
}
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 &&
info->bytes > block_group->sectorsize * 4)
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 = kzalloc(sizeof(struct btrfs_free_space),
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);
kfree(info);
}
return ret;
}
int btrfs_add_free_space(struct btrfs_block_group_cache *block_group,
u64 offset, u64 bytes)
{
struct btrfs_free_space *right_info = NULL;
struct btrfs_free_space *left_info = NULL;
struct btrfs_free_space *info = NULL;
int ret = 0;
info = kzalloc(sizeof(struct btrfs_free_space), GFP_NOFS);
if (!info)
return -ENOMEM;
info->offset = offset;
info->bytes = bytes;
spin_lock(&block_group->tree_lock);
/*
* 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 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
*/
if ((!left_info || left_info->bitmap) &&
(!right_info || right_info->bitmap)) {
ret = insert_into_bitmap(block_group, info);
if (ret < 0) {
goto out;
} else if (ret) {
ret = 0;
goto out;
}
}
if (right_info && !right_info->bitmap) {
unlink_free_space(block_group, right_info);
info->bytes += right_info->bytes;
kfree(right_info);
}
if (left_info && !left_info->bitmap &&
left_info->offset + left_info->bytes == offset) {
unlink_free_space(block_group, left_info);
info->offset = left_info->offset;
info->bytes += left_info->bytes;
kfree(left_info);
}
ret = link_free_space(block_group, info);
if (ret)
kfree(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--;
}
kfree(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
*/
kfree(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);
}
u64 btrfs_block_group_free_space(struct btrfs_block_group_cache *block_group)
{
struct btrfs_free_space *info;
struct rb_node *n;
u64 ret = 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);
ret += info->bytes;
}
return ret;
}
/*
* 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;
bool bitmap;
spin_lock(&cluster->lock);
if (cluster->block_group != block_group)
goto out;
bitmap = cluster->points_to_bitmap;
cluster->block_group = NULL;
cluster->window_start = 0;
list_del_init(&cluster->block_group_list);
cluster->points_to_bitmap = false;
if (bitmap)
goto out;
node = rb_first(&cluster->root);
while (node) {
entry = rb_entry(node, struct btrfs_free_space, offset_index);
node = rb_next(&entry->offset_index);
rb_erase(&entry->offset_index, &cluster->root);
BUG_ON(entry->bitmap);
tree_insert_offset(&block_group->free_space_offset,
entry->offset, &entry->offset_index, 0);
}
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);
unlink_free_space(block_group, info);
if (info->bitmap)
kfree(info->bitmap);
kfree(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) {
unlink_free_space(block_group, entry);
kfree(entry->bitmap);
kfree(entry);
block_group->total_bitmaps--;
recalculate_thresholds(block_group);
}
} else {
unlink_free_space(block_group, entry);
entry->offset += bytes;
entry->bytes -= bytes;
if (!entry->bytes)
kfree(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,
u64 bytes, u64 min_start)
{
struct btrfs_free_space *entry;
int err;
u64 search_start = cluster->window_start;
u64 search_bytes = bytes;
u64 ret = 0;
spin_lock(&block_group->tree_lock);
spin_lock(&cluster->lock);
if (!cluster->points_to_bitmap)
goto out;
if (cluster->block_group != block_group)
goto out;
/*
* search_start is the beginning of the bitmap, but at some point it may
* be a good idea to point to the actual start of the free area in the
* bitmap, so do the offset_to_bitmap trick anyway, and set bitmap_only
* to 1 to make sure we get the bitmap entry
*/
entry = tree_search_offset(block_group,
offset_to_bitmap(block_group, search_start),
1, 0);
if (!entry || !entry->bitmap)
goto out;
search_start = min_start;
search_bytes = bytes;
err = search_bitmap(block_group, entry, &search_start,
&search_bytes);
if (err)
goto out;
ret = search_start;
bitmap_clear_bits(block_group, entry, ret, bytes);
out:
spin_unlock(&cluster->lock);
spin_unlock(&block_group->tree_lock);
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;
if (cluster->points_to_bitmap)
return btrfs_alloc_from_bitmap(block_group, cluster, bytes,
min_start);
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->offset < min_start) {
struct rb_node *node;
node = rb_next(&entry->offset_index);
if (!node)
break;
entry = rb_entry(node, struct btrfs_free_space,
offset_index);
continue;
}
ret = entry->offset;
entry->offset += bytes;
entry->bytes -= bytes;
if (entry->bytes == 0) {
rb_erase(&entry->offset_index, &cluster->root);
kfree(entry);
}
break;
}
out:
spin_unlock(&cluster->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;
bool found = false;
i = offset_to_bit(entry->offset, block_group->sectorsize,
max_t(u64, offset, entry->offset));
search_bits = bytes_to_bits(min_bytes, block_group->sectorsize);
total_bits = bytes_to_bits(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 -1;
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;
cluster->points_to_bitmap = true;
return 0;
}
/*
* 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)
{
struct btrfs_free_space *entry = NULL;
struct rb_node *node;
struct btrfs_free_space *next;
struct btrfs_free_space *last = NULL;
u64 min_bytes;
u64 window_start;
u64 window_free;
u64 max_extent = 0;
bool found_bitmap = false;
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);
spin_lock(&cluster->lock);
/* someone already found a cluster, hooray */
if (cluster->block_group) {
ret = 0;
goto out;
}
again:
entry = tree_search_offset(block_group, offset, found_bitmap, 1);
if (!entry) {
ret = -ENOSPC;
goto out;
}
/*
* If found_bitmap is true, we exhausted our search for extent entries,
* and we just want to search all of the bitmaps that we can find, and
* ignore any extent entries we find.
*/
while (entry->bitmap || found_bitmap ||
(!entry->bitmap && entry->bytes < min_bytes)) {
struct rb_node *node = rb_next(&entry->offset_index);
if (entry->bitmap && entry->bytes > bytes + empty_size) {
ret = btrfs_bitmap_cluster(block_group, entry, cluster,
offset, bytes + empty_size,
min_bytes);
if (!ret)
goto got_it;
}
if (!node) {
ret = -ENOSPC;
goto out;
}
entry = rb_entry(node, struct btrfs_free_space, offset_index);
}
/*
* We already searched all the extent entries from the passed in offset
* to the end and didn't find enough space for the cluster, and we also
* didn't find any bitmaps that met our criteria, just go ahead and exit
*/
if (found_bitmap) {
ret = -ENOSPC;
goto out;
}
cluster->points_to_bitmap = false;
window_start = entry->offset;
window_free = entry->bytes;
last = entry;
max_extent = entry->bytes;
while (1) {
/* out window is just right, lets fill it */
if (window_free >= bytes + empty_size)
break;
node = rb_next(&last->offset_index);
if (!node) {
if (found_bitmap)
goto again;
ret = -ENOSPC;
goto out;
}
next = rb_entry(node, struct btrfs_free_space, offset_index);
/*
* we found a bitmap, so if this search doesn't result in a
* cluster, we know to go and search again for the bitmaps and
* start looking for space there
*/
if (next->bitmap) {
if (!found_bitmap)
offset = next->offset;
found_bitmap = true;
last = next;
continue;
}
/*
* we haven't filled the empty size and the window is
* very large. reset and try again
*/
if (next->offset - (last->offset + last->bytes) > 128 * 1024 ||
next->offset - window_start > (bytes + empty_size) * 2) {
entry = next;
window_start = entry->offset;
window_free = entry->bytes;
last = entry;
max_extent = entry->bytes;
} else {
last = next;
window_free += next->bytes;
if (entry->bytes > max_extent)
max_extent = entry->bytes;
}
}
cluster->window_start = entry->offset;
/*
* now we've found our entries, pull them out of the free space
* cache and put them into the cluster rbtree
*
* The cluster includes an rbtree, but only uses the offset index
* of each free space cache entry.
*/
while (1) {
node = rb_next(&entry->offset_index);
if (entry->bitmap && node) {
entry = rb_entry(node, struct btrfs_free_space,
offset_index);
continue;
} else if (entry->bitmap && !node) {
break;
}
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);
if (!node || entry == last)
break;
entry = rb_entry(node, struct btrfs_free_space, offset_index);
}
cluster->max_size = max_extent;
got_it:
ret = 0;
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;
cluster->points_to_bitmap = false;
INIT_LIST_HEAD(&cluster->block_group_list);
cluster->block_group = NULL;
}