linux/fs/btrfs/free-space-cache.c
Josef Bacik 25891f796d Btrfs: fix extent entry threshold calculation
There is a slight problem with the extent entry threshold calculation for the
free space cache.  We only adjust the threshold down as we add bitmaps, but
never actually adjust the threshold up as we add bitmaps.  This means we could
fragment the free space so badly that we end up using all bitmaps to describe
the free space, use all the free space which would result in the bitmaps being
freed, but then go to add free space again as we delete things and immediately
add bitmaps since the extent threshold would still be 0.  Now as we free
bitmaps the extent threshold will be ratcheted up to allow more extent entries
to be added.

Signed-off-by: Josef Bacik <jbacik@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-09-21 19:23:50 -04:00

1365 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/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_node = NULL;
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 = 0;
} 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_node = NULL;
cluster->max_size = 0;
cluster->points_to_bitmap = false;
INIT_LIST_HEAD(&cluster->block_group_list);
cluster->block_group = NULL;
}