- 根目录:
- fs
- btrfs
- inode-map.c
/*
* Copyright (C) 2007 Oracle. All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License v2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public
* License along with this program; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 021110-1307, USA.
*/
#include <linux/delay.h>
#include <linux/kthread.h>
#include <linux/pagemap.h>
#include "ctree.h"
#include "disk-io.h"
#include "free-space-cache.h"
#include "inode-map.h"
#include "transaction.h"
static int caching_kthread(void *data)
{
struct btrfs_root *root = data;
struct btrfs_fs_info *fs_info = root->fs_info;
struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
struct btrfs_key key;
struct btrfs_path *path;
struct extent_buffer *leaf;
u64 last = (u64)-1;
int slot;
int ret;
if (!btrfs_test_opt(root, INODE_MAP_CACHE))
return 0;
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
/* Since the commit root is read-only, we can safely skip locking. */
path->skip_locking = 1;
path->search_commit_root = 1;
path->reada = 2;
key.objectid = BTRFS_FIRST_FREE_OBJECTID;
key.offset = 0;
key.type = BTRFS_INODE_ITEM_KEY;
again:
/* need to make sure the commit_root doesn't disappear */
mutex_lock(&root->fs_commit_mutex);
ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
if (ret < 0)
goto out;
while (1) {
if (btrfs_fs_closing(fs_info))
goto out;
leaf = path->nodes[0];
slot = path->slots[0];
if (slot >= btrfs_header_nritems(leaf)) {
ret = btrfs_next_leaf(root, path);
if (ret < 0)
goto out;
else if (ret > 0)
break;
if (need_resched() ||
btrfs_transaction_in_commit(fs_info)) {
leaf = path->nodes[0];
if (btrfs_header_nritems(leaf) == 0) {
WARN_ON(1);
break;
}
/*
* Save the key so we can advances forward
* in the next search.
*/
btrfs_item_key_to_cpu(leaf, &key, 0);
btrfs_release_path(path);
root->cache_progress = last;
mutex_unlock(&root->fs_commit_mutex);
schedule_timeout(1);
goto again;
} else
continue;
}
btrfs_item_key_to_cpu(leaf, &key, slot);
if (key.type != BTRFS_INODE_ITEM_KEY)
goto next;
if (key.objectid >= root->highest_objectid)
break;
if (last != (u64)-1 && last + 1 != key.objectid) {
__btrfs_add_free_space(ctl, last + 1,
key.objectid - last - 1);
wake_up(&root->cache_wait);
}
last = key.objectid;
next:
path->slots[0]++;
}
if (last < root->highest_objectid - 1) {
__btrfs_add_free_space(ctl, last + 1,
root->highest_objectid - last - 1);
}
spin_lock(&root->cache_lock);
root->cached = BTRFS_CACHE_FINISHED;
spin_unlock(&root->cache_lock);
root->cache_progress = (u64)-1;
btrfs_unpin_free_ino(root);
out:
wake_up(&root->cache_wait);
mutex_unlock(&root->fs_commit_mutex);
btrfs_free_path(path);
return ret;
}
static void start_caching(struct btrfs_root *root)
{
struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
struct task_struct *tsk;
int ret;
u64 objectid;
if (!btrfs_test_opt(root, INODE_MAP_CACHE))
return;
spin_lock(&root->cache_lock);
if (root->cached != BTRFS_CACHE_NO) {
spin_unlock(&root->cache_lock);
return;
}
root->cached = BTRFS_CACHE_STARTED;
spin_unlock(&root->cache_lock);
ret = load_free_ino_cache(root->fs_info, root);
if (ret == 1) {
spin_lock(&root->cache_lock);
root->cached = BTRFS_CACHE_FINISHED;
spin_unlock(&root->cache_lock);
return;
}
/*
* It can be quite time-consuming to fill the cache by searching
* through the extent tree, and this can keep ino allocation path
* waiting. Therefore at start we quickly find out the highest
* inode number and we know we can use inode numbers which fall in
* [highest_ino + 1, BTRFS_LAST_FREE_OBJECTID].
*/
ret = btrfs_find_free_objectid(root, &objectid);
if (!ret && objectid <= BTRFS_LAST_FREE_OBJECTID) {
__btrfs_add_free_space(ctl, objectid,
BTRFS_LAST_FREE_OBJECTID - objectid + 1);
}
tsk = kthread_run(caching_kthread, root, "btrfs-ino-cache-%llu\n",
root->root_key.objectid);
BUG_ON(IS_ERR(tsk));
}
int btrfs_find_free_ino(struct btrfs_root *root, u64 *objectid)
{
if (!btrfs_test_opt(root, INODE_MAP_CACHE))
return btrfs_find_free_objectid(root, objectid);
again:
*objectid = btrfs_find_ino_for_alloc(root);
if (*objectid != 0)
return 0;
start_caching(root);
wait_event(root->cache_wait,
root->cached == BTRFS_CACHE_FINISHED ||
root->free_ino_ctl->free_space > 0);
if (root->cached == BTRFS_CACHE_FINISHED &&
root->free_ino_ctl->free_space == 0)
return -ENOSPC;
else
goto again;
}
void btrfs_return_ino(struct btrfs_root *root, u64 objectid)
{
struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
struct btrfs_free_space_ctl *pinned = root->free_ino_pinned;
if (!btrfs_test_opt(root, INODE_MAP_CACHE))
return;
again:
if (root->cached == BTRFS_CACHE_FINISHED) {
__btrfs_add_free_space(ctl, objectid, 1);
} else {
/*
* If we are in the process of caching free ino chunks,
* to avoid adding the same inode number to the free_ino
* tree twice due to cross transaction, we'll leave it
* in the pinned tree until a transaction is committed
* or the caching work is done.
*/
mutex_lock(&root->fs_commit_mutex);
spin_lock(&root->cache_lock);
if (root->cached == BTRFS_CACHE_FINISHED) {
spin_unlock(&root->cache_lock);
mutex_unlock(&root->fs_commit_mutex);
goto again;
}
spin_unlock(&root->cache_lock);
start_caching(root);
if (objectid <= root->cache_progress ||
objectid > root->highest_objectid)
__btrfs_add_free_space(ctl, objectid, 1);
else
__btrfs_add_free_space(pinned, objectid, 1);
mutex_unlock(&root->fs_commit_mutex);
}
}
/*
* When a transaction is committed, we'll move those inode numbers which
* are smaller than root->cache_progress from pinned tree to free_ino tree,
* and others will just be dropped, because the commit root we were
* searching has changed.
*
* Must be called with root->fs_commit_mutex held
*/
void btrfs_unpin_free_ino(struct btrfs_root *root)
{
struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
struct rb_root *rbroot = &root->free_ino_pinned->free_space_offset;
struct btrfs_free_space *info;
struct rb_node *n;
u64 count;
if (!btrfs_test_opt(root, INODE_MAP_CACHE))
return;
while (1) {
n = rb_first(rbroot);
if (!n)
break;
info = rb_entry(n, struct btrfs_free_space, offset_index);
BUG_ON(info->bitmap);
if (info->offset > root->cache_progress)
goto free;
else if (info->offset + info->bytes > root->cache_progress)
count = root->cache_progress - info->offset + 1;
else
count = info->bytes;
__btrfs_add_free_space(ctl, info->offset, count);
free:
rb_erase(&info->offset_index, rbroot);
kfree(info);
}
}
#define INIT_THRESHOLD (((1024 * 32) / 2) / sizeof(struct btrfs_free_space))
#define INODES_PER_BITMAP (PAGE_CACHE_SIZE * 8)
/*
* The goal is to keep the memory used by the free_ino tree won't
* exceed the memory if we use bitmaps only.
*/
static void recalculate_thresholds(struct btrfs_free_space_ctl *ctl)
{
struct btrfs_free_space *info;
struct rb_node *n;
int max_ino;
int max_bitmaps;
n = rb_last(&ctl->free_space_offset);
if (!n) {
ctl->extents_thresh = INIT_THRESHOLD;
return;
}
info = rb_entry(n, struct btrfs_free_space, offset_index);
/*
* Find the maximum inode number in the filesystem. Note we
* ignore the fact that this can be a bitmap, because we are
* not doing precise calculation.
*/
max_ino = info->bytes - 1;
max_bitmaps = ALIGN(max_ino, INODES_PER_BITMAP) / INODES_PER_BITMAP;
if (max_bitmaps <= ctl->total_bitmaps) {
ctl->extents_thresh = 0;
return;
}
ctl->extents_thresh = (max_bitmaps - ctl->total_bitmaps) *
PAGE_CACHE_SIZE / sizeof(*info);
}
/*
* We don't fall back to bitmap, if we are below the extents threshold
* or this chunk of inode numbers is a big one.
*/
static bool use_bitmap(struct btrfs_free_space_ctl *ctl,
struct btrfs_free_space *info)
{
if (ctl->free_extents < ctl->extents_thresh ||
info->bytes > INODES_PER_BITMAP / 10)
return false;
return true;
}
static struct btrfs_free_space_op free_ino_op = {
.recalc_thresholds = recalculate_thresholds,
.use_bitmap = use_bitmap,
};
static void pinned_recalc_thresholds(struct btrfs_free_space_ctl *ctl)
{
}
static bool pinned_use_bitmap(struct btrfs_free_space_ctl *ctl,
struct btrfs_free_space *info)
{
/*
* We always use extents for two reasons:
*
* - The pinned tree is only used during the process of caching
* work.
* - Make code simpler. See btrfs_unpin_free_ino().
*/
return false;
}
static struct btrfs_free_space_op pinned_free_ino_op = {
.recalc_thresholds = pinned_recalc_thresholds,
.use_bitmap = pinned_use_bitmap,
};
void btrfs_init_free_ino_ctl(struct btrfs_root *root)
{
struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
struct btrfs_free_space_ctl *pinned = root->free_ino_pinned;
spin_lock_init(&ctl->tree_lock);
ctl->unit = 1;
ctl->start = 0;
ctl->private = NULL;
ctl->op = &free_ino_op;
/*
* Initially we allow to use 16K of ram to cache chunks of
* inode numbers before we resort to bitmaps. This is somewhat
* arbitrary, but it will be adjusted in runtime.
*/
ctl->extents_thresh = INIT_THRESHOLD;
spin_lock_init(&pinned->tree_lock);
pinned->unit = 1;
pinned->start = 0;
pinned->private = NULL;
pinned->extents_thresh = 0;
pinned->op = &pinned_free_ino_op;
}
int btrfs_save_ino_cache(struct btrfs_root *root,
struct btrfs_trans_handle *trans)
{
struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
struct btrfs_path *path;
struct inode *inode;
u64 alloc_hint = 0;
int ret;
int prealloc;
bool retry = false;
/* only fs tree and subvol/snap needs ino cache */
if (root->root_key.objectid != BTRFS_FS_TREE_OBJECTID &&
(root->root_key.objectid < BTRFS_FIRST_FREE_OBJECTID ||
root->root_key.objectid > BTRFS_LAST_FREE_OBJECTID))
return 0;
/* Don't save inode cache if we are deleting this root */
if (btrfs_root_refs(&root->root_item) == 0 &&
root != root->fs_info->tree_root)
return 0;
if (!btrfs_test_opt(root, INODE_MAP_CACHE))
return 0;
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
again:
inode = lookup_free_ino_inode(root, path);
if (IS_ERR(inode) && PTR_ERR(inode) != -ENOENT) {
ret = PTR_ERR(inode);
goto out;
}
if (IS_ERR(inode)) {
BUG_ON(retry);
retry = true;
ret = create_free_ino_inode(root, trans, path);
if (ret)
goto out;
goto again;
}
BTRFS_I(inode)->generation = 0;
ret = btrfs_update_inode(trans, root, inode);
WARN_ON(ret);
if (i_size_read(inode) > 0) {
ret = btrfs_truncate_free_space_cache(root, trans, path, inode);
if (ret)
goto out_put;
}
spin_lock(&root->cache_lock);
if (root->cached != BTRFS_CACHE_FINISHED) {
ret = -1;
spin_unlock(&root->cache_lock);
goto out_put;
}
spin_unlock(&root->cache_lock);
spin_lock(&ctl->tree_lock);
prealloc = sizeof(struct btrfs_free_space) * ctl->free_extents;
prealloc = ALIGN(prealloc, PAGE_CACHE_SIZE);
prealloc += ctl->total_bitmaps * PAGE_CACHE_SIZE;
spin_unlock(&ctl->tree_lock);
/* Just to make sure we have enough space */
prealloc += 8 * PAGE_CACHE_SIZE;
ret = btrfs_check_data_free_space(inode, prealloc);
if (ret)
goto out_put;
ret = btrfs_prealloc_file_range_trans(inode, trans, 0, 0, prealloc,
prealloc, prealloc, &alloc_hint);
if (ret)
goto out_put;
btrfs_free_reserved_data_space(inode, prealloc);
out_put:
iput(inode);
out:
if (ret == 0)
ret = btrfs_write_out_ino_cache(root, trans, path);
btrfs_free_path(path);
return ret;
}
static int btrfs_find_highest_objectid(struct btrfs_root *root, u64 *objectid)
{
struct btrfs_path *path;
int ret;
struct extent_buffer *l;
struct btrfs_key search_key;
struct btrfs_key found_key;
int slot;
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
search_key.objectid = BTRFS_LAST_FREE_OBJECTID;
search_key.type = -1;
search_key.offset = (u64)-1;
ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
if (ret < 0)
goto error;
BUG_ON(ret == 0);
if (path->slots[0] > 0) {
slot = path->slots[0] - 1;
l = path->nodes[0];
btrfs_item_key_to_cpu(l, &found_key, slot);
*objectid = max_t(u64, found_key.objectid,
BTRFS_FIRST_FREE_OBJECTID - 1);
} else {
*objectid = BTRFS_FIRST_FREE_OBJECTID - 1;
}
ret = 0;
error:
btrfs_free_path(path);
return ret;
}
int btrfs_find_free_objectid(struct btrfs_root *root, u64 *objectid)
{
int ret;
mutex_lock(&root->objectid_mutex);
if (unlikely(root->highest_objectid < BTRFS_FIRST_FREE_OBJECTID)) {
ret = btrfs_find_highest_objectid(root,
&root->highest_objectid);
if (ret)
goto out;
}
if (unlikely(root->highest_objectid >= BTRFS_LAST_FREE_OBJECTID)) {
ret = -ENOSPC;
goto out;
}
*objectid = ++root->highest_objectid;
ret = 0;
out:
mutex_unlock(&root->objectid_mutex);
return ret;
}