linux/fs/btrfs/inode-map.c
Qu Wenruo 8702ba9396 btrfs: qgroup: Always free PREALLOC META reserve in btrfs_delalloc_release_extents()
[Background]
Btrfs qgroup uses two types of reserved space for METADATA space,
PERTRANS and PREALLOC.

PERTRANS is metadata space reserved for each transaction started by
btrfs_start_transaction().
While PREALLOC is for delalloc, where we reserve space before joining a
transaction, and finally it will be converted to PERTRANS after the
writeback is done.

[Inconsistency]
However there is inconsistency in how we handle PREALLOC metadata space.

The most obvious one is:
In btrfs_buffered_write():
	btrfs_delalloc_release_extents(BTRFS_I(inode), reserve_bytes, true);

We always free qgroup PREALLOC meta space.

While in btrfs_truncate_block():
	btrfs_delalloc_release_extents(BTRFS_I(inode), blocksize, (ret != 0));

We only free qgroup PREALLOC meta space when something went wrong.

[The Correct Behavior]
The correct behavior should be the one in btrfs_buffered_write(), we
should always free PREALLOC metadata space.

The reason is, the btrfs_delalloc_* mechanism works by:
- Reserve metadata first, even it's not necessary
  In btrfs_delalloc_reserve_metadata()

- Free the unused metadata space
  Normally in:
  btrfs_delalloc_release_extents()
  |- btrfs_inode_rsv_release()
     Here we do calculation on whether we should release or not.

E.g. for 64K buffered write, the metadata rsv works like:

/* The first page */
reserve_meta:	num_bytes=calc_inode_reservations()
free_meta:	num_bytes=0
total:		num_bytes=calc_inode_reservations()
/* The first page caused one outstanding extent, thus needs metadata
   rsv */

/* The 2nd page */
reserve_meta:	num_bytes=calc_inode_reservations()
free_meta:	num_bytes=calc_inode_reservations()
total:		not changed
/* The 2nd page doesn't cause new outstanding extent, needs no new meta
   rsv, so we free what we have reserved */

/* The 3rd~16th pages */
reserve_meta:	num_bytes=calc_inode_reservations()
free_meta:	num_bytes=calc_inode_reservations()
total:		not changed (still space for one outstanding extent)

This means, if btrfs_delalloc_release_extents() determines to free some
space, then those space should be freed NOW.
So for qgroup, we should call btrfs_qgroup_free_meta_prealloc() other
than btrfs_qgroup_convert_reserved_meta().

The good news is:
- The callers are not that hot
  The hottest caller is in btrfs_buffered_write(), which is already
  fixed by commit 336a8bb8e3 ("btrfs: Fix wrong
  btrfs_delalloc_release_extents parameter"). Thus it's not that
  easy to cause false EDQUOT.

- The trans commit in advance for qgroup would hide the bug
  Since commit f5fef45936 ("btrfs: qgroup: Make qgroup async transaction
  commit more aggressive"), when btrfs qgroup metadata free space is slow,
  it will try to commit transaction and free the wrongly converted
  PERTRANS space, so it's not that easy to hit such bug.

[FIX]
So to fix the problem, remove the @qgroup_free parameter for
btrfs_delalloc_release_extents(), and always pass true to
btrfs_inode_rsv_release().

Reported-by: Filipe Manana <fdmanana@suse.com>
Fixes: 43b18595d6 ("btrfs: qgroup: Use separate meta reservation type for delalloc")
CC: stable@vger.kernel.org # 4.19+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2019-10-15 18:50:07 +02:00

581 lines
15 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2007 Oracle. All rights reserved.
*/
#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"
#include "delalloc-space.h"
static void fail_caching_thread(struct btrfs_root *root)
{
struct btrfs_fs_info *fs_info = root->fs_info;
btrfs_warn(fs_info, "failed to start inode caching task");
btrfs_clear_pending_and_info(fs_info, INODE_MAP_CACHE,
"disabling inode map caching");
spin_lock(&root->ino_cache_lock);
root->ino_cache_state = BTRFS_CACHE_ERROR;
spin_unlock(&root->ino_cache_lock);
wake_up(&root->ino_cache_wait);
}
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(fs_info, INODE_MAP_CACHE))
return 0;
path = btrfs_alloc_path();
if (!path) {
fail_caching_thread(root);
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 = READA_FORWARD;
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 */
down_read(&fs_info->commit_root_sem);
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 (WARN_ON(btrfs_header_nritems(leaf) == 0))
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->ino_cache_progress = last;
up_read(&fs_info->commit_root_sem);
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(fs_info, ctl, last + 1,
key.objectid - last - 1);
wake_up(&root->ino_cache_wait);
}
last = key.objectid;
next:
path->slots[0]++;
}
if (last < root->highest_objectid - 1) {
__btrfs_add_free_space(fs_info, ctl, last + 1,
root->highest_objectid - last - 1);
}
spin_lock(&root->ino_cache_lock);
root->ino_cache_state = BTRFS_CACHE_FINISHED;
spin_unlock(&root->ino_cache_lock);
root->ino_cache_progress = (u64)-1;
btrfs_unpin_free_ino(root);
out:
wake_up(&root->ino_cache_wait);
up_read(&fs_info->commit_root_sem);
btrfs_free_path(path);
return ret;
}
static void start_caching(struct btrfs_root *root)
{
struct btrfs_fs_info *fs_info = root->fs_info;
struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
struct task_struct *tsk;
int ret;
u64 objectid;
if (!btrfs_test_opt(fs_info, INODE_MAP_CACHE))
return;
spin_lock(&root->ino_cache_lock);
if (root->ino_cache_state != BTRFS_CACHE_NO) {
spin_unlock(&root->ino_cache_lock);
return;
}
root->ino_cache_state = BTRFS_CACHE_STARTED;
spin_unlock(&root->ino_cache_lock);
ret = load_free_ino_cache(fs_info, root);
if (ret == 1) {
spin_lock(&root->ino_cache_lock);
root->ino_cache_state = BTRFS_CACHE_FINISHED;
spin_unlock(&root->ino_cache_lock);
wake_up(&root->ino_cache_wait);
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(fs_info, ctl, objectid,
BTRFS_LAST_FREE_OBJECTID - objectid + 1);
wake_up(&root->ino_cache_wait);
}
tsk = kthread_run(caching_kthread, root, "btrfs-ino-cache-%llu",
root->root_key.objectid);
if (IS_ERR(tsk))
fail_caching_thread(root);
}
int btrfs_find_free_ino(struct btrfs_root *root, u64 *objectid)
{
if (!btrfs_test_opt(root->fs_info, 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->ino_cache_wait,
root->ino_cache_state == BTRFS_CACHE_FINISHED ||
root->ino_cache_state == BTRFS_CACHE_ERROR ||
root->free_ino_ctl->free_space > 0);
if (root->ino_cache_state == BTRFS_CACHE_FINISHED &&
root->free_ino_ctl->free_space == 0)
return -ENOSPC;
else if (root->ino_cache_state == BTRFS_CACHE_ERROR)
return btrfs_find_free_objectid(root, objectid);
else
goto again;
}
void btrfs_return_ino(struct btrfs_root *root, u64 objectid)
{
struct btrfs_fs_info *fs_info = root->fs_info;
struct btrfs_free_space_ctl *pinned = root->free_ino_pinned;
if (!btrfs_test_opt(fs_info, INODE_MAP_CACHE))
return;
again:
if (root->ino_cache_state == BTRFS_CACHE_FINISHED) {
__btrfs_add_free_space(fs_info, pinned, objectid, 1);
} else {
down_write(&fs_info->commit_root_sem);
spin_lock(&root->ino_cache_lock);
if (root->ino_cache_state == BTRFS_CACHE_FINISHED) {
spin_unlock(&root->ino_cache_lock);
up_write(&fs_info->commit_root_sem);
goto again;
}
spin_unlock(&root->ino_cache_lock);
start_caching(root);
__btrfs_add_free_space(fs_info, pinned, objectid, 1);
up_write(&fs_info->commit_root_sem);
}
}
/*
* When a transaction is committed, we'll move those inode numbers which are
* smaller than root->ino_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_info->commit_root_sem 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;
spinlock_t *rbroot_lock = &root->free_ino_pinned->tree_lock;
struct btrfs_free_space *info;
struct rb_node *n;
u64 count;
if (!btrfs_test_opt(root->fs_info, INODE_MAP_CACHE))
return;
while (1) {
spin_lock(rbroot_lock);
n = rb_first(rbroot);
if (!n) {
spin_unlock(rbroot_lock);
break;
}
info = rb_entry(n, struct btrfs_free_space, offset_index);
BUG_ON(info->bitmap); /* Logic error */
if (info->offset > root->ino_cache_progress)
count = 0;
else
count = min(root->ino_cache_progress - info->offset + 1,
info->bytes);
rb_erase(&info->offset_index, rbroot);
spin_unlock(rbroot_lock);
if (count)
__btrfs_add_free_space(root->fs_info, ctl,
info->offset, count);
kmem_cache_free(btrfs_free_space_cachep, info);
}
}
#define INIT_THRESHOLD ((SZ_32K / 2) / sizeof(struct btrfs_free_space))
#define INODES_PER_BITMAP (PAGE_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_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 const 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 const 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;
INIT_LIST_HEAD(&ctl->trimming_ranges);
mutex_init(&ctl->cache_writeout_mutex);
/*
* 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_fs_info *fs_info = root->fs_info;
struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;
struct btrfs_path *path;
struct inode *inode;
struct btrfs_block_rsv *rsv;
struct extent_changeset *data_reserved = NULL;
u64 num_bytes;
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)
return 0;
if (!btrfs_test_opt(fs_info, INODE_MAP_CACHE))
return 0;
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
rsv = trans->block_rsv;
trans->block_rsv = &fs_info->trans_block_rsv;
num_bytes = trans->bytes_reserved;
/*
* 1 item for inode item insertion if need
* 4 items for inode item update (in the worst case)
* 1 items for slack space if we need do truncation
* 1 item for free space object
* 3 items for pre-allocation
*/
trans->bytes_reserved = btrfs_calc_insert_metadata_size(fs_info, 10);
ret = btrfs_block_rsv_add(root, trans->block_rsv,
trans->bytes_reserved,
BTRFS_RESERVE_NO_FLUSH);
if (ret)
goto out;
trace_btrfs_space_reservation(fs_info, "ino_cache", trans->transid,
trans->bytes_reserved, 1);
again:
inode = lookup_free_ino_inode(root, path);
if (IS_ERR(inode) && (PTR_ERR(inode) != -ENOENT || retry)) {
ret = PTR_ERR(inode);
goto out_release;
}
if (IS_ERR(inode)) {
BUG_ON(retry); /* Logic error */
retry = true;
ret = create_free_ino_inode(root, trans, path);
if (ret)
goto out_release;
goto again;
}
BTRFS_I(inode)->generation = 0;
ret = btrfs_update_inode(trans, root, inode);
if (ret) {
btrfs_abort_transaction(trans, ret);
goto out_put;
}
if (i_size_read(inode) > 0) {
ret = btrfs_truncate_free_space_cache(trans, NULL, inode);
if (ret) {
if (ret != -ENOSPC)
btrfs_abort_transaction(trans, ret);
goto out_put;
}
}
spin_lock(&root->ino_cache_lock);
if (root->ino_cache_state != BTRFS_CACHE_FINISHED) {
ret = -1;
spin_unlock(&root->ino_cache_lock);
goto out_put;
}
spin_unlock(&root->ino_cache_lock);
spin_lock(&ctl->tree_lock);
prealloc = sizeof(struct btrfs_free_space) * ctl->free_extents;
prealloc = ALIGN(prealloc, PAGE_SIZE);
prealloc += ctl->total_bitmaps * PAGE_SIZE;
spin_unlock(&ctl->tree_lock);
/* Just to make sure we have enough space */
prealloc += 8 * PAGE_SIZE;
ret = btrfs_delalloc_reserve_space(inode, &data_reserved, 0, prealloc);
if (ret)
goto out_put;
ret = btrfs_prealloc_file_range_trans(inode, trans, 0, 0, prealloc,
prealloc, prealloc, &alloc_hint);
if (ret) {
btrfs_delalloc_release_extents(BTRFS_I(inode), prealloc);
btrfs_delalloc_release_metadata(BTRFS_I(inode), prealloc, true);
goto out_put;
}
ret = btrfs_write_out_ino_cache(root, trans, path, inode);
btrfs_delalloc_release_extents(BTRFS_I(inode), prealloc);
out_put:
iput(inode);
out_release:
trace_btrfs_space_reservation(fs_info, "ino_cache", trans->transid,
trans->bytes_reserved, 0);
btrfs_block_rsv_release(fs_info, trans->block_rsv,
trans->bytes_reserved);
out:
trans->block_rsv = rsv;
trans->bytes_reserved = num_bytes;
btrfs_free_path(path);
extent_changeset_free(data_reserved);
return ret;
}
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); /* Corruption */
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_LAST_FREE_OBJECTID)) {
btrfs_warn(root->fs_info,
"the objectid of root %llu reaches its highest value",
root->root_key.objectid);
ret = -ENOSPC;
goto out;
}
*objectid = ++root->highest_objectid;
ret = 0;
out:
mutex_unlock(&root->objectid_mutex);
return ret;
}