// SPDX-License-Identifier: GPL-2.0
#include "misc.h"
#include "ctree.h"
#include "block-rsv.h"
#include "space-info.h"
#include "transaction.h"
#include "block-group.h"
#include "fs.h"
#include "accessors.h"
/*
* HOW DO BLOCK RESERVES WORK
*
* Think of block_rsv's as buckets for logically grouped metadata
* reservations. Each block_rsv has a ->size and a ->reserved. ->size is
* how large we want our block rsv to be, ->reserved is how much space is
* currently reserved for this block reserve.
*
* ->failfast exists for the truncate case, and is described below.
*
* NORMAL OPERATION
*
* -> Reserve
* Entrance: btrfs_block_rsv_add, btrfs_block_rsv_refill
*
* We call into btrfs_reserve_metadata_bytes() with our bytes, which is
* accounted for in space_info->bytes_may_use, and then add the bytes to
* ->reserved, and ->size in the case of btrfs_block_rsv_add.
*
* ->size is an over-estimation of how much we may use for a particular
* operation.
*
* -> Use
* Entrance: btrfs_use_block_rsv
*
* When we do a btrfs_alloc_tree_block() we call into btrfs_use_block_rsv()
* to determine the appropriate block_rsv to use, and then verify that
* ->reserved has enough space for our tree block allocation. Once
* successful we subtract fs_info->nodesize from ->reserved.
*
* -> Finish
* Entrance: btrfs_block_rsv_release
*
* We are finished with our operation, subtract our individual reservation
* from ->size, and then subtract ->size from ->reserved and free up the
* excess if there is any.
*
* There is some logic here to refill the delayed refs rsv or the global rsv
* as needed, otherwise the excess is subtracted from
* space_info->bytes_may_use.
*
* TYPES OF BLOCK RESERVES
*
* BLOCK_RSV_TRANS, BLOCK_RSV_DELOPS, BLOCK_RSV_CHUNK
* These behave normally, as described above, just within the confines of the
* lifetime of their particular operation (transaction for the whole trans
* handle lifetime, for example).
*
* BLOCK_RSV_GLOBAL
* It is impossible to properly account for all the space that may be required
* to make our extent tree updates. This block reserve acts as an overflow
* buffer in case our delayed refs reserve does not reserve enough space to
* update the extent tree.
*
* We can steal from this in some cases as well, notably on evict() or
* truncate() in order to help users recover from ENOSPC conditions.
*
* BLOCK_RSV_DELALLOC
* The individual item sizes are determined by the per-inode size
* calculations, which are described with the delalloc code. This is pretty
* straightforward, it's just the calculation of ->size encodes a lot of
* different items, and thus it gets used when updating inodes, inserting file
* extents, and inserting checksums.
*
* BLOCK_RSV_DELREFS
* We keep a running tally of how many delayed refs we have on the system.
* We assume each one of these delayed refs are going to use a full
* reservation. We use the transaction items and pre-reserve space for every
* operation, and use this reservation to refill any gap between ->size and
* ->reserved that may exist.
*
* From there it's straightforward, removing a delayed ref means we remove its
* count from ->size and free up reservations as necessary. Since this is
* the most dynamic block reserve in the system, we will try to refill this
* block reserve first with any excess returned by any other block reserve.
*
* BLOCK_RSV_EMPTY
* This is the fallback block reserve to make us try to reserve space if we
* don't have a specific bucket for this allocation. It is mostly used for
* updating the device tree and such, since that is a separate pool we're
* content to just reserve space from the space_info on demand.
*
* BLOCK_RSV_TEMP
* This is used by things like truncate and iput. We will temporarily
* allocate a block reserve, set it to some size, and then truncate bytes
* until we have no space left. With ->failfast set we'll simply return
* ENOSPC from btrfs_use_block_rsv() to signal that we need to unwind and try
* to make a new reservation. This is because these operations are
* unbounded, so we want to do as much work as we can, and then back off and
* re-reserve.
*/
static u64 block_rsv_release_bytes(struct btrfs_fs_info *fs_info,
struct btrfs_block_rsv *block_rsv,
struct btrfs_block_rsv *dest, u64 num_bytes,
u64 *qgroup_to_release_ret)
{
struct btrfs_space_info *space_info = block_rsv->space_info;
u64 qgroup_to_release = 0;
u64 ret;
spin_lock(&block_rsv->lock);
if (num_bytes == (u64)-1) {
num_bytes = block_rsv->size;
qgroup_to_release = block_rsv->qgroup_rsv_size;
}
block_rsv->size -= num_bytes;
if (block_rsv->reserved >= block_rsv->size) {
num_bytes = block_rsv->reserved - block_rsv->size;
block_rsv->reserved = block_rsv->size;
block_rsv->full = true;
} else {
num_bytes = 0;
}
if (qgroup_to_release_ret &&
block_rsv->qgroup_rsv_reserved >= block_rsv->qgroup_rsv_size) {
qgroup_to_release = block_rsv->qgroup_rsv_reserved -
block_rsv->qgroup_rsv_size;
block_rsv->qgroup_rsv_reserved = block_rsv->qgroup_rsv_size;
} else {
qgroup_to_release = 0;
}
spin_unlock(&block_rsv->lock);
ret = num_bytes;
if (num_bytes > 0) {
if (dest) {
spin_lock(&dest->lock);
if (!dest->full) {
u64 bytes_to_add;
bytes_to_add = dest->size - dest->reserved;
bytes_to_add = min(num_bytes, bytes_to_add);
dest->reserved += bytes_to_add;
if (dest->reserved >= dest->size)
dest->full = true;
num_bytes -= bytes_to_add;
}
spin_unlock(&dest->lock);
}
if (num_bytes)
btrfs_space_info_free_bytes_may_use(fs_info,
space_info,
num_bytes);
}
if (qgroup_to_release_ret)
*qgroup_to_release_ret = qgroup_to_release;
return ret;
}
int btrfs_block_rsv_migrate(struct btrfs_block_rsv *src,
struct btrfs_block_rsv *dst, u64 num_bytes,
bool update_size)
{
int ret;
ret = btrfs_block_rsv_use_bytes(src, num_bytes);
if (ret)
return ret;
btrfs_block_rsv_add_bytes(dst, num_bytes, update_size);
return 0;
}
void btrfs_init_block_rsv(struct btrfs_block_rsv *rsv, enum btrfs_rsv_type type)
{
memset(rsv, 0, sizeof(*rsv));
spin_lock_init(&rsv->lock);
rsv->type = type;
}
void btrfs_init_metadata_block_rsv(struct btrfs_fs_info *fs_info,
struct btrfs_block_rsv *rsv,
enum btrfs_rsv_type type)
{
btrfs_init_block_rsv(rsv, type);
rsv->space_info = btrfs_find_space_info(fs_info,
BTRFS_BLOCK_GROUP_METADATA);
}
struct btrfs_block_rsv *btrfs_alloc_block_rsv(struct btrfs_fs_info *fs_info,
enum btrfs_rsv_type type)
{
struct btrfs_block_rsv *block_rsv;
block_rsv = kmalloc(sizeof(*block_rsv), GFP_NOFS);
if (!block_rsv)
return NULL;
btrfs_init_metadata_block_rsv(fs_info, block_rsv, type);
return block_rsv;
}
void btrfs_free_block_rsv(struct btrfs_fs_info *fs_info,
struct btrfs_block_rsv *rsv)
{
if (!rsv)
return;
btrfs_block_rsv_release(fs_info, rsv, (u64)-1, NULL);
kfree(rsv);
}
int btrfs_block_rsv_add(struct btrfs_fs_info *fs_info,
struct btrfs_block_rsv *block_rsv, u64 num_bytes,
enum btrfs_reserve_flush_enum flush)
{
int ret;
if (num_bytes == 0)
return 0;
ret = btrfs_reserve_metadata_bytes(fs_info, block_rsv->space_info,
num_bytes, flush);
if (!ret)
btrfs_block_rsv_add_bytes(block_rsv, num_bytes, true);
return ret;
}
int btrfs_block_rsv_check(struct btrfs_block_rsv *block_rsv, int min_percent)
{
u64 num_bytes = 0;
int ret = -ENOSPC;
spin_lock(&block_rsv->lock);
num_bytes = mult_perc(block_rsv->size, min_percent);
if (block_rsv->reserved >= num_bytes)
ret = 0;
spin_unlock(&block_rsv->lock);
return ret;
}
int btrfs_block_rsv_refill(struct btrfs_fs_info *fs_info,
struct btrfs_block_rsv *block_rsv, u64 num_bytes,
enum btrfs_reserve_flush_enum flush)
{
int ret = -ENOSPC;
if (!block_rsv)
return 0;
spin_lock(&block_rsv->lock);
if (block_rsv->reserved >= num_bytes)
ret = 0;
else
num_bytes -= block_rsv->reserved;
spin_unlock(&block_rsv->lock);
if (!ret)
return 0;
ret = btrfs_reserve_metadata_bytes(fs_info, block_rsv->space_info,
num_bytes, flush);
if (!ret) {
btrfs_block_rsv_add_bytes(block_rsv, num_bytes, false);
return 0;
}
return ret;
}
u64 btrfs_block_rsv_release(struct btrfs_fs_info *fs_info,
struct btrfs_block_rsv *block_rsv, u64 num_bytes,
u64 *qgroup_to_release)
{
struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
struct btrfs_block_rsv *delayed_rsv = &fs_info->delayed_refs_rsv;
struct btrfs_block_rsv *target = NULL;
/*
* If we are a delayed block reserve then push to the global rsv,
* otherwise dump into the global delayed reserve if it is not full.
*/
if (block_rsv->type == BTRFS_BLOCK_RSV_DELOPS)
target = global_rsv;
else if (block_rsv != global_rsv && !btrfs_block_rsv_full(delayed_rsv))
target = delayed_rsv;
if (target && block_rsv->space_info != target->space_info)
target = NULL;
return block_rsv_release_bytes(fs_info, block_rsv, target, num_bytes,
qgroup_to_release);
}
int btrfs_block_rsv_use_bytes(struct btrfs_block_rsv *block_rsv, u64 num_bytes)
{
int ret = -ENOSPC;
spin_lock(&block_rsv->lock);
if (block_rsv->reserved >= num_bytes) {
block_rsv->reserved -= num_bytes;
if (block_rsv->reserved < block_rsv->size)
block_rsv->full = false;
ret = 0;
}
spin_unlock(&block_rsv->lock);
return ret;
}
void btrfs_block_rsv_add_bytes(struct btrfs_block_rsv *block_rsv,
u64 num_bytes, bool update_size)
{
spin_lock(&block_rsv->lock);
block_rsv->reserved += num_bytes;
if (update_size)
block_rsv->size += num_bytes;
else if (block_rsv->reserved >= block_rsv->size)
block_rsv->full = true;
spin_unlock(&block_rsv->lock);
}
void btrfs_update_global_block_rsv(struct btrfs_fs_info *fs_info)
{
struct btrfs_block_rsv *block_rsv = &fs_info->global_block_rsv;
struct btrfs_space_info *sinfo = block_rsv->space_info;
struct btrfs_root *root, *tmp;
u64 num_bytes = btrfs_root_used(&fs_info->tree_root->root_item);
unsigned int min_items = 1;
/*
* The global block rsv is based on the size of the extent tree, the
* checksum tree and the root tree. If the fs is empty we want to set
* it to a minimal amount for safety.
*
* We also are going to need to modify the minimum of the tree root and
* any global roots we could touch.
*/
read_lock(&fs_info->global_root_lock);
rbtree_postorder_for_each_entry_safe(root, tmp, &fs_info->global_root_tree,
rb_node) {
if (btrfs_root_id(root) == BTRFS_EXTENT_TREE_OBJECTID ||
btrfs_root_id(root) == BTRFS_CSUM_TREE_OBJECTID ||
btrfs_root_id(root) == BTRFS_FREE_SPACE_TREE_OBJECTID) {
num_bytes += btrfs_root_used(&root->root_item);
min_items++;
}
}
read_unlock(&fs_info->global_root_lock);
if (btrfs_fs_compat_ro(fs_info, BLOCK_GROUP_TREE)) {
num_bytes += btrfs_root_used(&fs_info->block_group_root->root_item);
min_items++;
}
if (btrfs_fs_incompat(fs_info, RAID_STRIPE_TREE)) {
num_bytes += btrfs_root_used(&fs_info->stripe_root->root_item);
min_items++;
}
/*
* But we also want to reserve enough space so we can do the fallback
* global reserve for an unlink, which is an additional
* BTRFS_UNLINK_METADATA_UNITS items.
*
* But we also need space for the delayed ref updates from the unlink,
* so add BTRFS_UNLINK_METADATA_UNITS units for delayed refs, one for
* each unlink metadata item.
*/
min_items += BTRFS_UNLINK_METADATA_UNITS;
num_bytes = max_t(u64, num_bytes,
btrfs_calc_insert_metadata_size(fs_info, min_items) +
btrfs_calc_delayed_ref_bytes(fs_info,
BTRFS_UNLINK_METADATA_UNITS));
spin_lock(&sinfo->lock);
spin_lock(&block_rsv->lock);
block_rsv->size = min_t(u64, num_bytes, SZ_512M);
if (block_rsv->reserved < block_rsv->size) {
num_bytes = block_rsv->size - block_rsv->reserved;
btrfs_space_info_update_bytes_may_use(fs_info, sinfo,
num_bytes);
block_rsv->reserved = block_rsv->size;
} else if (block_rsv->reserved > block_rsv->size) {
num_bytes = block_rsv->reserved - block_rsv->size;
btrfs_space_info_update_bytes_may_use(fs_info, sinfo,
-num_bytes);
block_rsv->reserved = block_rsv->size;
btrfs_try_granting_tickets(fs_info, sinfo);
}
block_rsv->full = (block_rsv->reserved == block_rsv->size);
if (block_rsv->size >= sinfo->total_bytes)
sinfo->force_alloc = CHUNK_ALLOC_FORCE;
spin_unlock(&block_rsv->lock);
spin_unlock(&sinfo->lock);
}
void btrfs_init_root_block_rsv(struct btrfs_root *root)
{
struct btrfs_fs_info *fs_info = root->fs_info;
switch (btrfs_root_id(root)) {
case BTRFS_CSUM_TREE_OBJECTID:
case BTRFS_EXTENT_TREE_OBJECTID:
case BTRFS_FREE_SPACE_TREE_OBJECTID:
case BTRFS_BLOCK_GROUP_TREE_OBJECTID:
case BTRFS_RAID_STRIPE_TREE_OBJECTID:
root->block_rsv = &fs_info->delayed_refs_rsv;
break;
case BTRFS_ROOT_TREE_OBJECTID:
case BTRFS_DEV_TREE_OBJECTID:
case BTRFS_QUOTA_TREE_OBJECTID:
root->block_rsv = &fs_info->global_block_rsv;
break;
case BTRFS_CHUNK_TREE_OBJECTID:
root->block_rsv = &fs_info->chunk_block_rsv;
break;
default:
root->block_rsv = NULL;
break;
}
}
void btrfs_init_global_block_rsv(struct btrfs_fs_info *fs_info)
{
struct btrfs_space_info *space_info;
space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_SYSTEM);
fs_info->chunk_block_rsv.space_info = space_info;
space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
fs_info->global_block_rsv.space_info = space_info;
fs_info->trans_block_rsv.space_info = space_info;
fs_info->empty_block_rsv.space_info = space_info;
fs_info->delayed_block_rsv.space_info = space_info;
fs_info->delayed_refs_rsv.space_info = space_info;
btrfs_update_global_block_rsv(fs_info);
}
void btrfs_release_global_block_rsv(struct btrfs_fs_info *fs_info)
{
btrfs_block_rsv_release(fs_info, &fs_info->global_block_rsv, (u64)-1,
NULL);
WARN_ON(fs_info->trans_block_rsv.size > 0);
WARN_ON(fs_info->trans_block_rsv.reserved > 0);
WARN_ON(fs_info->chunk_block_rsv.size > 0);
WARN_ON(fs_info->chunk_block_rsv.reserved > 0);
WARN_ON(fs_info->delayed_block_rsv.size > 0);
WARN_ON(fs_info->delayed_block_rsv.reserved > 0);
WARN_ON(fs_info->delayed_refs_rsv.reserved > 0);
WARN_ON(fs_info->delayed_refs_rsv.size > 0);
}
static struct btrfs_block_rsv *get_block_rsv(
const struct btrfs_trans_handle *trans,
const struct btrfs_root *root)
{
struct btrfs_fs_info *fs_info = root->fs_info;
struct btrfs_block_rsv *block_rsv = NULL;
if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state) ||
(root == fs_info->uuid_root) ||
(trans->adding_csums && btrfs_root_id(root) == BTRFS_CSUM_TREE_OBJECTID))
block_rsv = trans->block_rsv;
if (!block_rsv)
block_rsv = root->block_rsv;
if (!block_rsv)
block_rsv = &fs_info->empty_block_rsv;
return block_rsv;
}
struct btrfs_block_rsv *btrfs_use_block_rsv(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
u32 blocksize)
{
struct btrfs_fs_info *fs_info = root->fs_info;
struct btrfs_block_rsv *block_rsv;
struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
int ret;
bool global_updated = false;
block_rsv = get_block_rsv(trans, root);
if (unlikely(btrfs_block_rsv_size(block_rsv) == 0))
goto try_reserve;
again:
ret = btrfs_block_rsv_use_bytes(block_rsv, blocksize);
if (!ret)
return block_rsv;
if (block_rsv->failfast)
return ERR_PTR(ret);
if (block_rsv->type == BTRFS_BLOCK_RSV_GLOBAL && !global_updated) {
global_updated = true;
btrfs_update_global_block_rsv(fs_info);
goto again;
}
/*
* The global reserve still exists to save us from ourselves, so don't
* warn_on if we are short on our delayed refs reserve.
*/
if (block_rsv->type != BTRFS_BLOCK_RSV_DELREFS &&
btrfs_test_opt(fs_info, ENOSPC_DEBUG)) {
static DEFINE_RATELIMIT_STATE(_rs,
DEFAULT_RATELIMIT_INTERVAL * 10,
/*DEFAULT_RATELIMIT_BURST*/ 1);
if (__ratelimit(&_rs))
WARN(1, KERN_DEBUG
"BTRFS: block rsv %d returned %d\n",
block_rsv->type, ret);
}
try_reserve:
ret = btrfs_reserve_metadata_bytes(fs_info, block_rsv->space_info,
blocksize, BTRFS_RESERVE_NO_FLUSH);
if (!ret)
return block_rsv;
/*
* If we couldn't reserve metadata bytes try and use some from
* the global reserve if its space type is the same as the global
* reservation.
*/
if (block_rsv->type != BTRFS_BLOCK_RSV_GLOBAL &&
block_rsv->space_info == global_rsv->space_info) {
ret = btrfs_block_rsv_use_bytes(global_rsv, blocksize);
if (!ret)
return global_rsv;
}
/*
* All hope is lost, but of course our reservations are overly
* pessimistic, so instead of possibly having an ENOSPC abort here, try
* one last time to force a reservation if there's enough actual space
* on disk to make the reservation.
*/
ret = btrfs_reserve_metadata_bytes(fs_info, block_rsv->space_info, blocksize,
BTRFS_RESERVE_FLUSH_EMERGENCY);
if (!ret)
return block_rsv;
return ERR_PTR(ret);
}
int btrfs_check_trunc_cache_free_space(const struct btrfs_fs_info *fs_info,
struct btrfs_block_rsv *rsv)
{
u64 needed_bytes;
int ret;
/* 1 for slack space, 1 for updating the inode */
needed_bytes = btrfs_calc_insert_metadata_size(fs_info, 1) +
btrfs_calc_metadata_size(fs_info, 1);
spin_lock(&rsv->lock);
if (rsv->reserved < needed_bytes)
ret = -ENOSPC;
else
ret = 0;
spin_unlock(&rsv->lock);
return ret;
}
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