// SPDX-License-Identifier: GPL-2.0
#include "linux/spinlock.h"
#include <linux/minmax.h>
#include "misc.h"
#include "ctree.h"
#include "space-info.h"
#include "sysfs.h"
#include "volumes.h"
#include "free-space-cache.h"
#include "ordered-data.h"
#include "transaction.h"
#include "block-group.h"
#include "fs.h"
#include "accessors.h"
#include "extent-tree.h"
/*
* HOW DOES SPACE RESERVATION WORK
*
* If you want to know about delalloc specifically, there is a separate comment
* for that with the delalloc code. This comment is about how the whole system
* works generally.
*
* BASIC CONCEPTS
*
* 1) space_info. This is the ultimate arbiter of how much space we can use.
* There's a description of the bytes_ fields with the struct declaration,
* refer to that for specifics on each field. Suffice it to say that for
* reservations we care about total_bytes - SUM(space_info->bytes_) when
* determining if there is space to make an allocation. There is a space_info
* for METADATA, SYSTEM, and DATA areas.
*
* 2) block_rsv's. These are basically buckets for every different type of
* metadata reservation we have. You can see the comment in the block_rsv
* code on the rules for each type, but generally block_rsv->reserved is how
* much space is accounted for in space_info->bytes_may_use.
*
* 3) btrfs_calc*_size. These are the worst case calculations we used based
* on the number of items we will want to modify. We have one for changing
* items, and one for inserting new items. Generally we use these helpers to
* determine the size of the block reserves, and then use the actual bytes
* values to adjust the space_info counters.
*
* MAKING RESERVATIONS, THE NORMAL CASE
*
* We call into either btrfs_reserve_data_bytes() or
* btrfs_reserve_metadata_bytes(), depending on which we're looking for, with
* num_bytes we want to reserve.
*
* ->reserve
* space_info->bytes_may_reserve += num_bytes
*
* ->extent allocation
* Call btrfs_add_reserved_bytes() which does
* space_info->bytes_may_reserve -= num_bytes
* space_info->bytes_reserved += extent_bytes
*
* ->insert reference
* Call btrfs_update_block_group() which does
* space_info->bytes_reserved -= extent_bytes
* space_info->bytes_used += extent_bytes
*
* MAKING RESERVATIONS, FLUSHING NORMALLY (non-priority)
*
* Assume we are unable to simply make the reservation because we do not have
* enough space
*
* -> __reserve_bytes
* create a reserve_ticket with ->bytes set to our reservation, add it to
* the tail of space_info->tickets, kick async flush thread
*
* ->handle_reserve_ticket
* wait on ticket->wait for ->bytes to be reduced to 0, or ->error to be set
* on the ticket.
*
* -> btrfs_async_reclaim_metadata_space/btrfs_async_reclaim_data_space
* Flushes various things attempting to free up space.
*
* -> btrfs_try_granting_tickets()
* This is called by anything that either subtracts space from
* space_info->bytes_may_use, ->bytes_pinned, etc, or adds to the
* space_info->total_bytes. This loops through the ->priority_tickets and
* then the ->tickets list checking to see if the reservation can be
* completed. If it can the space is added to space_info->bytes_may_use and
* the ticket is woken up.
*
* -> ticket wakeup
* Check if ->bytes == 0, if it does we got our reservation and we can carry
* on, if not return the appropriate error (ENOSPC, but can be EINTR if we
* were interrupted.)
*
* MAKING RESERVATIONS, FLUSHING HIGH PRIORITY
*
* Same as the above, except we add ourselves to the
* space_info->priority_tickets, and we do not use ticket->wait, we simply
* call flush_space() ourselves for the states that are safe for us to call
* without deadlocking and hope for the best.
*
* THE FLUSHING STATES
*
* Generally speaking we will have two cases for each state, a "nice" state
* and a "ALL THE THINGS" state. In btrfs we delay a lot of work in order to
* reduce the locking over head on the various trees, and even to keep from
* doing any work at all in the case of delayed refs. Each of these delayed
* things however hold reservations, and so letting them run allows us to
* reclaim space so we can make new reservations.
*
* FLUSH_DELAYED_ITEMS
* Every inode has a delayed item to update the inode. Take a simple write
* for example, we would update the inode item at write time to update the
* mtime, and then again at finish_ordered_io() time in order to update the
* isize or bytes. We keep these delayed items to coalesce these operations
* into a single operation done on demand. These are an easy way to reclaim
* metadata space.
*
* FLUSH_DELALLOC
* Look at the delalloc comment to get an idea of how much space is reserved
* for delayed allocation. We can reclaim some of this space simply by
* running delalloc, but usually we need to wait for ordered extents to
* reclaim the bulk of this space.
*
* FLUSH_DELAYED_REFS
* We have a block reserve for the outstanding delayed refs space, and every
* delayed ref operation holds a reservation. Running these is a quick way
* to reclaim space, but we want to hold this until the end because COW can
* churn a lot and we can avoid making some extent tree modifications if we
* are able to delay for as long as possible.
*
* ALLOC_CHUNK
* We will skip this the first time through space reservation, because of
* overcommit and we don't want to have a lot of useless metadata space when
* our worst case reservations will likely never come true.
*
* RUN_DELAYED_IPUTS
* If we're freeing inodes we're likely freeing checksums, file extent
* items, and extent tree items. Loads of space could be freed up by these
* operations, however they won't be usable until the transaction commits.
*
* COMMIT_TRANS
* This will commit the transaction. Historically we had a lot of logic
* surrounding whether or not we'd commit the transaction, but this waits born
* out of a pre-tickets era where we could end up committing the transaction
* thousands of times in a row without making progress. Now thanks to our
* ticketing system we know if we're not making progress and can error
* everybody out after a few commits rather than burning the disk hoping for
* a different answer.
*
* OVERCOMMIT
*
* Because we hold so many reservations for metadata we will allow you to
* reserve more space than is currently free in the currently allocate
* metadata space. This only happens with metadata, data does not allow
* overcommitting.
*
* You can see the current logic for when we allow overcommit in
* btrfs_can_overcommit(), but it only applies to unallocated space. If there
* is no unallocated space to be had, all reservations are kept within the
* free space in the allocated metadata chunks.
*
* Because of overcommitting, you generally want to use the
* btrfs_can_overcommit() logic for metadata allocations, as it does the right
* thing with or without extra unallocated space.
*/
u64 __pure btrfs_space_info_used(const struct btrfs_space_info *s_info,
bool may_use_included)
{
ASSERT(s_info);
return s_info->bytes_used + s_info->bytes_reserved +
s_info->bytes_pinned + s_info->bytes_readonly +
s_info->bytes_zone_unusable +
(may_use_included ? s_info->bytes_may_use : 0);
}
/*
* after adding space to the filesystem, we need to clear the full flags
* on all the space infos.
*/
void btrfs_clear_space_info_full(struct btrfs_fs_info *info)
{
struct list_head *head = &info->space_info;
struct btrfs_space_info *found;
list_for_each_entry(found, head, list)
found->full = 0;
}
/*
* Block groups with more than this value (percents) of unusable space will be
* scheduled for background reclaim.
*/
#define BTRFS_DEFAULT_ZONED_RECLAIM_THRESH (75)
#define BTRFS_UNALLOC_BLOCK_GROUP_TARGET (10ULL)
/*
* Calculate chunk size depending on volume type (regular or zoned).
*/
static u64 calc_chunk_size(const struct btrfs_fs_info *fs_info, u64 flags)
{
if (btrfs_is_zoned(fs_info))
return fs_info->zone_size;
ASSERT(flags & BTRFS_BLOCK_GROUP_TYPE_MASK);
if (flags & BTRFS_BLOCK_GROUP_DATA)
return BTRFS_MAX_DATA_CHUNK_SIZE;
else if (flags & BTRFS_BLOCK_GROUP_SYSTEM)
return SZ_32M;
/* Handle BTRFS_BLOCK_GROUP_METADATA */
if (fs_info->fs_devices->total_rw_bytes > 50ULL * SZ_1G)
return SZ_1G;
return SZ_256M;
}
/*
* Update default chunk size.
*/
void btrfs_update_space_info_chunk_size(struct btrfs_space_info *space_info,
u64 chunk_size)
{
WRITE_ONCE(space_info->chunk_size, chunk_size);
}
static int create_space_info(struct btrfs_fs_info *info, u64 flags)
{
struct btrfs_space_info *space_info;
int i;
int ret;
space_info = kzalloc(sizeof(*space_info), GFP_NOFS);
if (!space_info)
return -ENOMEM;
space_info->fs_info = info;
for (i = 0; i < BTRFS_NR_RAID_TYPES; i++)
INIT_LIST_HEAD(&space_info->block_groups[i]);
init_rwsem(&space_info->groups_sem);
spin_lock_init(&space_info->lock);
space_info->flags = flags & BTRFS_BLOCK_GROUP_TYPE_MASK;
space_info->force_alloc = CHUNK_ALLOC_NO_FORCE;
INIT_LIST_HEAD(&space_info->ro_bgs);
INIT_LIST_HEAD(&space_info->tickets);
INIT_LIST_HEAD(&space_info->priority_tickets);
space_info->clamp = 1;
btrfs_update_space_info_chunk_size(space_info, calc_chunk_size(info, flags));
if (btrfs_is_zoned(info))
space_info->bg_reclaim_threshold = BTRFS_DEFAULT_ZONED_RECLAIM_THRESH;
ret = btrfs_sysfs_add_space_info_type(info, space_info);
if (ret)
return ret;
list_add(&space_info->list, &info->space_info);
if (flags & BTRFS_BLOCK_GROUP_DATA)
info->data_sinfo = space_info;
return ret;
}
int btrfs_init_space_info(struct btrfs_fs_info *fs_info)
{
struct btrfs_super_block *disk_super;
u64 features;
u64 flags;
int mixed = 0;
int ret;
disk_super = fs_info->super_copy;
if (!btrfs_super_root(disk_super))
return -EINVAL;
features = btrfs_super_incompat_flags(disk_super);
if (features & BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS)
mixed = 1;
flags = BTRFS_BLOCK_GROUP_SYSTEM;
ret = create_space_info(fs_info, flags);
if (ret)
goto out;
if (mixed) {
flags = BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA;
ret = create_space_info(fs_info, flags);
} else {
flags = BTRFS_BLOCK_GROUP_METADATA;
ret = create_space_info(fs_info, flags);
if (ret)
goto out;
flags = BTRFS_BLOCK_GROUP_DATA;
ret = create_space_info(fs_info, flags);
}
out:
return ret;
}
void btrfs_add_bg_to_space_info(struct btrfs_fs_info *info,
struct btrfs_block_group *block_group)
{
struct btrfs_space_info *found;
int factor, index;
factor = btrfs_bg_type_to_factor(block_group->flags);
found = btrfs_find_space_info(info, block_group->flags);
ASSERT(found);
spin_lock(&found->lock);
found->total_bytes += block_group->length;
found->disk_total += block_group->length * factor;
found->bytes_used += block_group->used;
found->disk_used += block_group->used * factor;
found->bytes_readonly += block_group->bytes_super;
btrfs_space_info_update_bytes_zone_unusable(info, found, block_group->zone_unusable);
if (block_group->length > 0)
found->full = 0;
btrfs_try_granting_tickets(info, found);
spin_unlock(&found->lock);
block_group->space_info = found;
index = btrfs_bg_flags_to_raid_index(block_group->flags);
down_write(&found->groups_sem);
list_add_tail(&block_group->list, &found->block_groups[index]);
up_write(&found->groups_sem);
}
struct btrfs_space_info *btrfs_find_space_info(struct btrfs_fs_info *info,
u64 flags)
{
struct list_head *head = &info->space_info;
struct btrfs_space_info *found;
flags &= BTRFS_BLOCK_GROUP_TYPE_MASK;
list_for_each_entry(found, head, list) {
if (found->flags & flags)
return found;
}
return NULL;
}
static u64 calc_effective_data_chunk_size(struct btrfs_fs_info *fs_info)
{
struct btrfs_space_info *data_sinfo;
u64 data_chunk_size;
/*
* Calculate the data_chunk_size, space_info->chunk_size is the
* "optimal" chunk size based on the fs size. However when we actually
* allocate the chunk we will strip this down further, making it no
* more than 10% of the disk or 1G, whichever is smaller.
*
* On the zoned mode, we need to use zone_size (= data_sinfo->chunk_size)
* as it is.
*/
data_sinfo = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_DATA);
if (btrfs_is_zoned(fs_info))
return data_sinfo->chunk_size;
data_chunk_size = min(data_sinfo->chunk_size,
mult_perc(fs_info->fs_devices->total_rw_bytes, 10));
return min_t(u64, data_chunk_size, SZ_1G);
}
static u64 calc_available_free_space(struct btrfs_fs_info *fs_info,
const struct btrfs_space_info *space_info,
enum btrfs_reserve_flush_enum flush)
{
u64 profile;
u64 avail;
u64 data_chunk_size;
int factor;
if (space_info->flags & BTRFS_BLOCK_GROUP_SYSTEM)
profile = btrfs_system_alloc_profile(fs_info);
else
profile = btrfs_metadata_alloc_profile(fs_info);
avail = atomic64_read(&fs_info->free_chunk_space);
/*
* If we have dup, raid1 or raid10 then only half of the free
* space is actually usable. For raid56, the space info used
* doesn't include the parity drive, so we don't have to
* change the math
*/
factor = btrfs_bg_type_to_factor(profile);
avail = div_u64(avail, factor);
if (avail == 0)
return 0;
data_chunk_size = calc_effective_data_chunk_size(fs_info);
/*
* Since data allocations immediately use block groups as part of the
* reservation, because we assume that data reservations will == actual
* usage, we could potentially overcommit and then immediately have that
* available space used by a data allocation, which could put us in a
* bind when we get close to filling the file system.
*
* To handle this simply remove the data_chunk_size from the available
* space. If we are relatively empty this won't affect our ability to
* overcommit much, and if we're very close to full it'll keep us from
* getting into a position where we've given ourselves very little
* metadata wiggle room.
*/
if (avail <= data_chunk_size)
return 0;
avail -= data_chunk_size;
/*
* If we aren't flushing all things, let us overcommit up to
* 1/2th of the space. If we can flush, don't let us overcommit
* too much, let it overcommit up to 1/8 of the space.
*/
if (flush == BTRFS_RESERVE_FLUSH_ALL)
avail >>= 3;
else
avail >>= 1;
/*
* On the zoned mode, we always allocate one zone as one chunk.
* Returning non-zone size alingned bytes here will result in
* less pressure for the async metadata reclaim process, and it
* will over-commit too much leading to ENOSPC. Align down to the
* zone size to avoid that.
*/
if (btrfs_is_zoned(fs_info))
avail = ALIGN_DOWN(avail, fs_info->zone_size);
return avail;
}
int btrfs_can_overcommit(struct btrfs_fs_info *fs_info,
const struct btrfs_space_info *space_info, u64 bytes,
enum btrfs_reserve_flush_enum flush)
{
u64 avail;
u64 used;
/* Don't overcommit when in mixed mode */
if (space_info->flags & BTRFS_BLOCK_GROUP_DATA)
return 0;
used = btrfs_space_info_used(space_info, true);
avail = calc_available_free_space(fs_info, space_info, flush);
if (used + bytes < space_info->total_bytes + avail)
return 1;
return 0;
}
static void remove_ticket(struct btrfs_space_info *space_info,
struct reserve_ticket *ticket)
{
if (!list_empty(&ticket->list)) {
list_del_init(&ticket->list);
ASSERT(space_info->reclaim_size >= ticket->bytes);
space_info->reclaim_size -= ticket->bytes;
}
}
/*
* This is for space we already have accounted in space_info->bytes_may_use, so
* basically when we're returning space from block_rsv's.
*/
void btrfs_try_granting_tickets(struct btrfs_fs_info *fs_info,
struct btrfs_space_info *space_info)
{
struct list_head *head;
enum btrfs_reserve_flush_enum flush = BTRFS_RESERVE_NO_FLUSH;
lockdep_assert_held(&space_info->lock);
head = &space_info->priority_tickets;
again:
while (!list_empty(head)) {
struct reserve_ticket *ticket;
u64 used = btrfs_space_info_used(space_info, true);
ticket = list_first_entry(head, struct reserve_ticket, list);
/* Check and see if our ticket can be satisfied now. */
if ((used + ticket->bytes <= space_info->total_bytes) ||
btrfs_can_overcommit(fs_info, space_info, ticket->bytes,
flush)) {
btrfs_space_info_update_bytes_may_use(fs_info,
space_info,
ticket->bytes);
remove_ticket(space_info, ticket);
ticket->bytes = 0;
space_info->tickets_id++;
wake_up(&ticket->wait);
} else {
break;
}
}
if (head == &space_info->priority_tickets) {
head = &space_info->tickets;
flush = BTRFS_RESERVE_FLUSH_ALL;
goto again;
}
}
#define DUMP_BLOCK_RSV(fs_info, rsv_name) \
do { \
struct btrfs_block_rsv *__rsv = &(fs_info)->rsv_name; \
spin_lock(&__rsv->lock); \
btrfs_info(fs_info, #rsv_name ": size %llu reserved %llu", \
__rsv->size, __rsv->reserved); \
spin_unlock(&__rsv->lock); \
} while (0)
static const char *space_info_flag_to_str(const struct btrfs_space_info *space_info)
{
switch (space_info->flags) {
case BTRFS_BLOCK_GROUP_SYSTEM:
return "SYSTEM";
case BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA:
return "DATA+METADATA";
case BTRFS_BLOCK_GROUP_DATA:
return "DATA";
case BTRFS_BLOCK_GROUP_METADATA:
return "METADATA";
default:
return "UNKNOWN";
}
}
static void dump_global_block_rsv(struct btrfs_fs_info *fs_info)
{
DUMP_BLOCK_RSV(fs_info, global_block_rsv);
DUMP_BLOCK_RSV(fs_info, trans_block_rsv);
DUMP_BLOCK_RSV(fs_info, chunk_block_rsv);
DUMP_BLOCK_RSV(fs_info, delayed_block_rsv);
DUMP_BLOCK_RSV(fs_info, delayed_refs_rsv);
}
static void __btrfs_dump_space_info(const struct btrfs_fs_info *fs_info,
const struct btrfs_space_info *info)
{
const char *flag_str = space_info_flag_to_str(info);
lockdep_assert_held(&info->lock);
/* The free space could be negative in case of overcommit */
btrfs_info(fs_info, "space_info %s has %lld free, is %sfull",
flag_str,
(s64)(info->total_bytes - btrfs_space_info_used(info, true)),
info->full ? "" : "not ");
btrfs_info(fs_info,
"space_info total=%llu, used=%llu, pinned=%llu, reserved=%llu, may_use=%llu, readonly=%llu zone_unusable=%llu",
info->total_bytes, info->bytes_used, info->bytes_pinned,
info->bytes_reserved, info->bytes_may_use,
info->bytes_readonly, info->bytes_zone_unusable);
}
void btrfs_dump_space_info(struct btrfs_fs_info *fs_info,
struct btrfs_space_info *info, u64 bytes,
int dump_block_groups)
{
struct btrfs_block_group *cache;
u64 total_avail = 0;
int index = 0;
spin_lock(&info->lock);
__btrfs_dump_space_info(fs_info, info);
dump_global_block_rsv(fs_info);
spin_unlock(&info->lock);
if (!dump_block_groups)
return;
down_read(&info->groups_sem);
again:
list_for_each_entry(cache, &info->block_groups[index], list) {
u64 avail;
spin_lock(&cache->lock);
avail = cache->length - cache->used - cache->pinned -
cache->reserved - cache->bytes_super - cache->zone_unusable;
btrfs_info(fs_info,
"block group %llu has %llu bytes, %llu used %llu pinned %llu reserved %llu delalloc %llu super %llu zone_unusable (%llu bytes available) %s",
cache->start, cache->length, cache->used, cache->pinned,
cache->reserved, cache->delalloc_bytes,
cache->bytes_super, cache->zone_unusable,
avail, cache->ro ? "[readonly]" : "");
spin_unlock(&cache->lock);
btrfs_dump_free_space(cache, bytes);
total_avail += avail;
}
if (++index < BTRFS_NR_RAID_TYPES)
goto again;
up_read(&info->groups_sem);
btrfs_info(fs_info, "%llu bytes available across all block groups", total_avail);
}
static inline u64 calc_reclaim_items_nr(const struct btrfs_fs_info *fs_info,
u64 to_reclaim)
{
u64 bytes;
u64 nr;
bytes = btrfs_calc_insert_metadata_size(fs_info, 1);
nr = div64_u64(to_reclaim, bytes);
if (!nr)
nr = 1;
return nr;
}
/*
* shrink metadata reservation for delalloc
*/
static void shrink_delalloc(struct btrfs_fs_info *fs_info,
struct btrfs_space_info *space_info,
u64 to_reclaim, bool wait_ordered,
bool for_preempt)
{
struct btrfs_trans_handle *trans;
u64 delalloc_bytes;
u64 ordered_bytes;
u64 items;
long time_left;
int loops;
delalloc_bytes = percpu_counter_sum_positive(&fs_info->delalloc_bytes);
ordered_bytes = percpu_counter_sum_positive(&fs_info->ordered_bytes);
if (delalloc_bytes == 0 && ordered_bytes == 0)
return;
/* Calc the number of the pages we need flush for space reservation */
if (to_reclaim == U64_MAX) {
items = U64_MAX;
} else {
/*
* to_reclaim is set to however much metadata we need to
* reclaim, but reclaiming that much data doesn't really track
* exactly. What we really want to do is reclaim full inode's
* worth of reservations, however that's not available to us
* here. We will take a fraction of the delalloc bytes for our
* flushing loops and hope for the best. Delalloc will expand
* the amount we write to cover an entire dirty extent, which
* will reclaim the metadata reservation for that range. If
* it's not enough subsequent flush stages will be more
* aggressive.
*/
to_reclaim = max(to_reclaim, delalloc_bytes >> 3);
items = calc_reclaim_items_nr(fs_info, to_reclaim) * 2;
}
trans = current->journal_info;
/*
* If we are doing more ordered than delalloc we need to just wait on
* ordered extents, otherwise we'll waste time trying to flush delalloc
* that likely won't give us the space back we need.
*/
if (ordered_bytes > delalloc_bytes && !for_preempt)
wait_ordered = true;
loops = 0;
while ((delalloc_bytes || ordered_bytes) && loops < 3) {
u64 temp = min(delalloc_bytes, to_reclaim) >> PAGE_SHIFT;
long nr_pages = min_t(u64, temp, LONG_MAX);
int async_pages;
btrfs_start_delalloc_roots(fs_info, nr_pages, true);
/*
* We need to make sure any outstanding async pages are now
* processed before we continue. This is because things like
* sync_inode() try to be smart and skip writing if the inode is
* marked clean. We don't use filemap_fwrite for flushing
* because we want to control how many pages we write out at a
* time, thus this is the only safe way to make sure we've
* waited for outstanding compressed workers to have started
* their jobs and thus have ordered extents set up properly.
*
* This exists because we do not want to wait for each
* individual inode to finish its async work, we simply want to
* start the IO on everybody, and then come back here and wait
* for all of the async work to catch up. Once we're done with
* that we know we'll have ordered extents for everything and we
* can decide if we wait for that or not.
*
* If we choose to replace this in the future, make absolutely
* sure that the proper waiting is being done in the async case,
* as there have been bugs in that area before.
*/
async_pages = atomic_read(&fs_info->async_delalloc_pages);
if (!async_pages)
goto skip_async;
/*
* We don't want to wait forever, if we wrote less pages in this
* loop than we have outstanding, only wait for that number of
* pages, otherwise we can wait for all async pages to finish
* before continuing.
*/
if (async_pages > nr_pages)
async_pages -= nr_pages;
else
async_pages = 0;
wait_event(fs_info->async_submit_wait,
atomic_read(&fs_info->async_delalloc_pages) <=
async_pages);
skip_async:
loops++;
if (wait_ordered && !trans) {
btrfs_wait_ordered_roots(fs_info, items, NULL);
} else {
time_left = schedule_timeout_killable(1);
if (time_left)
break;
}
/*
* If we are for preemption we just want a one-shot of delalloc
* flushing so we can stop flushing if we decide we don't need
* to anymore.
*/
if (for_preempt)
break;
spin_lock(&space_info->lock);
if (list_empty(&space_info->tickets) &&
list_empty(&space_info->priority_tickets)) {
spin_unlock(&space_info->lock);
break;
}
spin_unlock(&space_info->lock);
delalloc_bytes = percpu_counter_sum_positive(
&fs_info->delalloc_bytes);
ordered_bytes = percpu_counter_sum_positive(
&fs_info->ordered_bytes);
}
}
/*
* Try to flush some data based on policy set by @state. This is only advisory
* and may fail for various reasons. The caller is supposed to examine the
* state of @space_info to detect the outcome.
*/
static void flush_space(struct btrfs_fs_info *fs_info,
struct btrfs_space_info *space_info, u64 num_bytes,
enum btrfs_flush_state state, bool for_preempt)
{
struct btrfs_root *root = fs_info->tree_root;
struct btrfs_trans_handle *trans;
int nr;
int ret = 0;
switch (state) {
case FLUSH_DELAYED_ITEMS_NR:
case FLUSH_DELAYED_ITEMS:
if (state == FLUSH_DELAYED_ITEMS_NR)
nr = calc_reclaim_items_nr(fs_info, num_bytes) * 2;
else
nr = -1;
trans = btrfs_join_transaction_nostart(root);
if (IS_ERR(trans)) {
ret = PTR_ERR(trans);
if (ret == -ENOENT)
ret = 0;
break;
}
ret = btrfs_run_delayed_items_nr(trans, nr);
btrfs_end_transaction(trans);
break;
case FLUSH_DELALLOC:
case FLUSH_DELALLOC_WAIT:
case FLUSH_DELALLOC_FULL:
if (state == FLUSH_DELALLOC_FULL)
num_bytes = U64_MAX;
shrink_delalloc(fs_info, space_info, num_bytes,
state != FLUSH_DELALLOC, for_preempt);
break;
case FLUSH_DELAYED_REFS_NR:
case FLUSH_DELAYED_REFS:
trans = btrfs_join_transaction_nostart(root);
if (IS_ERR(trans)) {
ret = PTR_ERR(trans);
if (ret == -ENOENT)
ret = 0;
break;
}
if (state == FLUSH_DELAYED_REFS_NR)
btrfs_run_delayed_refs(trans, num_bytes);
else
btrfs_run_delayed_refs(trans, 0);
btrfs_end_transaction(trans);
break;
case ALLOC_CHUNK:
case ALLOC_CHUNK_FORCE:
trans = btrfs_join_transaction(root);
if (IS_ERR(trans)) {
ret = PTR_ERR(trans);
break;
}
ret = btrfs_chunk_alloc(trans,
btrfs_get_alloc_profile(fs_info, space_info->flags),
(state == ALLOC_CHUNK) ? CHUNK_ALLOC_NO_FORCE :
CHUNK_ALLOC_FORCE);
btrfs_end_transaction(trans);
if (ret > 0 || ret == -ENOSPC)
ret = 0;
break;
case RUN_DELAYED_IPUTS:
/*
* If we have pending delayed iputs then we could free up a
* bunch of pinned space, so make sure we run the iputs before
* we do our pinned bytes check below.
*/
btrfs_run_delayed_iputs(fs_info);
btrfs_wait_on_delayed_iputs(fs_info);
break;
case COMMIT_TRANS:
ASSERT(current->journal_info == NULL);
/*
* We don't want to start a new transaction, just attach to the
* current one or wait it fully commits in case its commit is
* happening at the moment. Note: we don't use a nostart join
* because that does not wait for a transaction to fully commit
* (only for it to be unblocked, state TRANS_STATE_UNBLOCKED).
*/
ret = btrfs_commit_current_transaction(root);
break;
default:
ret = -ENOSPC;
break;
}
trace_btrfs_flush_space(fs_info, space_info->flags, num_bytes, state,
ret, for_preempt);
return;
}
static u64 btrfs_calc_reclaim_metadata_size(struct btrfs_fs_info *fs_info,
const struct btrfs_space_info *space_info)
{
u64 used;
u64 avail;
u64 to_reclaim = space_info->reclaim_size;
lockdep_assert_held(&space_info->lock);
avail = calc_available_free_space(fs_info, space_info,
BTRFS_RESERVE_FLUSH_ALL);
used = btrfs_space_info_used(space_info, true);
/*
* We may be flushing because suddenly we have less space than we had
* before, and now we're well over-committed based on our current free
* space. If that's the case add in our overage so we make sure to put
* appropriate pressure on the flushing state machine.
*/
if (space_info->total_bytes + avail < used)
to_reclaim += used - (space_info->total_bytes + avail);
return to_reclaim;
}
static bool need_preemptive_reclaim(struct btrfs_fs_info *fs_info,
const struct btrfs_space_info *space_info)
{
const u64 global_rsv_size = btrfs_block_rsv_reserved(&fs_info->global_block_rsv);
u64 ordered, delalloc;
u64 thresh;
u64 used;
thresh = mult_perc(space_info->total_bytes, 90);
lockdep_assert_held(&space_info->lock);
/* If we're just plain full then async reclaim just slows us down. */
if ((space_info->bytes_used + space_info->bytes_reserved +
global_rsv_size) >= thresh)
return false;
used = space_info->bytes_may_use + space_info->bytes_pinned;
/* The total flushable belongs to the global rsv, don't flush. */
if (global_rsv_size >= used)
return false;
/*
* 128MiB is 1/4 of the maximum global rsv size. If we have less than
* that devoted to other reservations then there's no sense in flushing,
* we don't have a lot of things that need flushing.
*/
if (used - global_rsv_size <= SZ_128M)
return false;
/*
* We have tickets queued, bail so we don't compete with the async
* flushers.
*/
if (space_info->reclaim_size)
return false;
/*
* If we have over half of the free space occupied by reservations or
* pinned then we want to start flushing.
*
* We do not do the traditional thing here, which is to say
*
* if (used >= ((total_bytes + avail) / 2))
* return 1;
*
* because this doesn't quite work how we want. If we had more than 50%
* of the space_info used by bytes_used and we had 0 available we'd just
* constantly run the background flusher. Instead we want it to kick in
* if our reclaimable space exceeds our clamped free space.
*
* Our clamping range is 2^1 -> 2^8. Practically speaking that means
* the following:
*
* Amount of RAM Minimum threshold Maximum threshold
*
* 256GiB 1GiB 128GiB
* 128GiB 512MiB 64GiB
* 64GiB 256MiB 32GiB
* 32GiB 128MiB 16GiB
* 16GiB 64MiB 8GiB
*
* These are the range our thresholds will fall in, corresponding to how
* much delalloc we need for the background flusher to kick in.
*/
thresh = calc_available_free_space(fs_info, space_info,
BTRFS_RESERVE_FLUSH_ALL);
used = space_info->bytes_used + space_info->bytes_reserved +
space_info->bytes_readonly + global_rsv_size;
if (used < space_info->total_bytes)
thresh += space_info->total_bytes - used;
thresh >>= space_info->clamp;
used = space_info->bytes_pinned;
/*
* If we have more ordered bytes than delalloc bytes then we're either
* doing a lot of DIO, or we simply don't have a lot of delalloc waiting
* around. Preemptive flushing is only useful in that it can free up
* space before tickets need to wait for things to finish. In the case
* of ordered extents, preemptively waiting on ordered extents gets us
* nothing, if our reservations are tied up in ordered extents we'll
* simply have to slow down writers by forcing them to wait on ordered
* extents.
*
* In the case that ordered is larger than delalloc, only include the
* block reserves that we would actually be able to directly reclaim
* from. In this case if we're heavy on metadata operations this will
* clearly be heavy enough to warrant preemptive flushing. In the case
* of heavy DIO or ordered reservations, preemptive flushing will just
* waste time and cause us to slow down.
*
* We want to make sure we truly are maxed out on ordered however, so
* cut ordered in half, and if it's still higher than delalloc then we
* can keep flushing. This is to avoid the case where we start
* flushing, and now delalloc == ordered and we stop preemptively
* flushing when we could still have several gigs of delalloc to flush.
*/
ordered = percpu_counter_read_positive(&fs_info->ordered_bytes) >> 1;
delalloc = percpu_counter_read_positive(&fs_info->delalloc_bytes);
if (ordered >= delalloc)
used += btrfs_block_rsv_reserved(&fs_info->delayed_refs_rsv) +
btrfs_block_rsv_reserved(&fs_info->delayed_block_rsv);
else
used += space_info->bytes_may_use - global_rsv_size;
return (used >= thresh && !btrfs_fs_closing(fs_info) &&
!test_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state));
}
static bool steal_from_global_rsv(struct btrfs_fs_info *fs_info,
struct btrfs_space_info *space_info,
struct reserve_ticket *ticket)
{
struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
u64 min_bytes;
if (!ticket->steal)
return false;
if (global_rsv->space_info != space_info)
return false;
spin_lock(&global_rsv->lock);
min_bytes = mult_perc(global_rsv->size, 10);
if (global_rsv->reserved < min_bytes + ticket->bytes) {
spin_unlock(&global_rsv->lock);
return false;
}
global_rsv->reserved -= ticket->bytes;
remove_ticket(space_info, ticket);
ticket->bytes = 0;
wake_up(&ticket->wait);
space_info->tickets_id++;
if (global_rsv->reserved < global_rsv->size)
global_rsv->full = 0;
spin_unlock(&global_rsv->lock);
return true;
}
/*
* We've exhausted our flushing, start failing tickets.
*
* @fs_info - fs_info for this fs
* @space_info - the space info we were flushing
*
* We call this when we've exhausted our flushing ability and haven't made
* progress in satisfying tickets. The reservation code handles tickets in
* order, so if there is a large ticket first and then smaller ones we could
* very well satisfy the smaller tickets. This will attempt to wake up any
* tickets in the list to catch this case.
*
* This function returns true if it was able to make progress by clearing out
* other tickets, or if it stumbles across a ticket that was smaller than the
* first ticket.
*/
static bool maybe_fail_all_tickets(struct btrfs_fs_info *fs_info,
struct btrfs_space_info *space_info)
{
struct reserve_ticket *ticket;
u64 tickets_id = space_info->tickets_id;
const bool aborted = BTRFS_FS_ERROR(fs_info);
trace_btrfs_fail_all_tickets(fs_info, space_info);
if (btrfs_test_opt(fs_info, ENOSPC_DEBUG)) {
btrfs_info(fs_info, "cannot satisfy tickets, dumping space info");
__btrfs_dump_space_info(fs_info, space_info);
}
while (!list_empty(&space_info->tickets) &&
tickets_id == space_info->tickets_id) {
ticket = list_first_entry(&space_info->tickets,
struct reserve_ticket, list);
if (!aborted && steal_from_global_rsv(fs_info, space_info, ticket))
return true;
if (!aborted && btrfs_test_opt(fs_info, ENOSPC_DEBUG))
btrfs_info(fs_info, "failing ticket with %llu bytes",
ticket->bytes);
remove_ticket(space_info, ticket);
if (aborted)
ticket->error = -EIO;
else
ticket->error = -ENOSPC;
wake_up(&ticket->wait);
/*
* We're just throwing tickets away, so more flushing may not
* trip over btrfs_try_granting_tickets, so we need to call it
* here to see if we can make progress with the next ticket in
* the list.
*/
if (!aborted)
btrfs_try_granting_tickets(fs_info, space_info);
}
return (tickets_id != space_info->tickets_id);
}
/*
* This is for normal flushers, we can wait all goddamned day if we want to. We
* will loop and continuously try to flush as long as we are making progress.
* We count progress as clearing off tickets each time we have to loop.
*/
static void btrfs_async_reclaim_metadata_space(struct work_struct *work)
{
struct btrfs_fs_info *fs_info;
struct btrfs_space_info *space_info;
u64 to_reclaim;
enum btrfs_flush_state flush_state;
int commit_cycles = 0;
u64 last_tickets_id;
fs_info = container_of(work, struct btrfs_fs_info, async_reclaim_work);
space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
spin_lock(&space_info->lock);
to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info, space_info);
if (!to_reclaim) {
space_info->flush = 0;
spin_unlock(&space_info->lock);
return;
}
last_tickets_id = space_info->tickets_id;
spin_unlock(&space_info->lock);
flush_state = FLUSH_DELAYED_ITEMS_NR;
do {
flush_space(fs_info, space_info, to_reclaim, flush_state, false);
spin_lock(&space_info->lock);
if (list_empty(&space_info->tickets)) {
space_info->flush = 0;
spin_unlock(&space_info->lock);
return;
}
to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info,
space_info);
if (last_tickets_id == space_info->tickets_id) {
flush_state++;
} else {
last_tickets_id = space_info->tickets_id;
flush_state = FLUSH_DELAYED_ITEMS_NR;
if (commit_cycles)
commit_cycles--;
}
/*
* We do not want to empty the system of delalloc unless we're
* under heavy pressure, so allow one trip through the flushing
* logic before we start doing a FLUSH_DELALLOC_FULL.
*/
if (flush_state == FLUSH_DELALLOC_FULL && !commit_cycles)
flush_state++;
/*
* We don't want to force a chunk allocation until we've tried
* pretty hard to reclaim space. Think of the case where we
* freed up a bunch of space and so have a lot of pinned space
* to reclaim. We would rather use that than possibly create a
* underutilized metadata chunk. So if this is our first run
* through the flushing state machine skip ALLOC_CHUNK_FORCE and
* commit the transaction. If nothing has changed the next go
* around then we can force a chunk allocation.
*/
if (flush_state == ALLOC_CHUNK_FORCE && !commit_cycles)
flush_state++;
if (flush_state > COMMIT_TRANS) {
commit_cycles++;
if (commit_cycles > 2) {
if (maybe_fail_all_tickets(fs_info, space_info)) {
flush_state = FLUSH_DELAYED_ITEMS_NR;
commit_cycles--;
} else {
space_info->flush = 0;
}
} else {
flush_state = FLUSH_DELAYED_ITEMS_NR;
}
}
spin_unlock(&space_info->lock);
} while (flush_state <= COMMIT_TRANS);
}
/*
* This handles pre-flushing of metadata space before we get to the point that
* we need to start blocking threads on tickets. The logic here is different
* from the other flush paths because it doesn't rely on tickets to tell us how
* much we need to flush, instead it attempts to keep us below the 80% full
* watermark of space by flushing whichever reservation pool is currently the
* largest.
*/
static void btrfs_preempt_reclaim_metadata_space(struct work_struct *work)
{
struct btrfs_fs_info *fs_info;
struct btrfs_space_info *space_info;
struct btrfs_block_rsv *delayed_block_rsv;
struct btrfs_block_rsv *delayed_refs_rsv;
struct btrfs_block_rsv *global_rsv;
struct btrfs_block_rsv *trans_rsv;
int loops = 0;
fs_info = container_of(work, struct btrfs_fs_info,
preempt_reclaim_work);
space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
delayed_block_rsv = &fs_info->delayed_block_rsv;
delayed_refs_rsv = &fs_info->delayed_refs_rsv;
global_rsv = &fs_info->global_block_rsv;
trans_rsv = &fs_info->trans_block_rsv;
spin_lock(&space_info->lock);
while (need_preemptive_reclaim(fs_info, space_info)) {
enum btrfs_flush_state flush;
u64 delalloc_size = 0;
u64 to_reclaim, block_rsv_size;
const u64 global_rsv_size = btrfs_block_rsv_reserved(global_rsv);
loops++;
/*
* We don't have a precise counter for the metadata being
* reserved for delalloc, so we'll approximate it by subtracting
* out the block rsv's space from the bytes_may_use. If that
* amount is higher than the individual reserves, then we can
* assume it's tied up in delalloc reservations.
*/
block_rsv_size = global_rsv_size +
btrfs_block_rsv_reserved(delayed_block_rsv) +
btrfs_block_rsv_reserved(delayed_refs_rsv) +
btrfs_block_rsv_reserved(trans_rsv);
if (block_rsv_size < space_info->bytes_may_use)
delalloc_size = space_info->bytes_may_use - block_rsv_size;
/*
* We don't want to include the global_rsv in our calculation,
* because that's space we can't touch. Subtract it from the
* block_rsv_size for the next checks.
*/
block_rsv_size -= global_rsv_size;
/*
* We really want to avoid flushing delalloc too much, as it
* could result in poor allocation patterns, so only flush it if
* it's larger than the rest of the pools combined.
*/
if (delalloc_size > block_rsv_size) {
to_reclaim = delalloc_size;
flush = FLUSH_DELALLOC;
} else if (space_info->bytes_pinned >
(btrfs_block_rsv_reserved(delayed_block_rsv) +
btrfs_block_rsv_reserved(delayed_refs_rsv))) {
to_reclaim = space_info->bytes_pinned;
flush = COMMIT_TRANS;
} else if (btrfs_block_rsv_reserved(delayed_block_rsv) >
btrfs_block_rsv_reserved(delayed_refs_rsv)) {
to_reclaim = btrfs_block_rsv_reserved(delayed_block_rsv);
flush = FLUSH_DELAYED_ITEMS_NR;
} else {
to_reclaim = btrfs_block_rsv_reserved(delayed_refs_rsv);
flush = FLUSH_DELAYED_REFS_NR;
}
spin_unlock(&space_info->lock);
/*
* We don't want to reclaim everything, just a portion, so scale
* down the to_reclaim by 1/4. If it takes us down to 0,
* reclaim 1 items worth.
*/
to_reclaim >>= 2;
if (!to_reclaim)
to_reclaim = btrfs_calc_insert_metadata_size(fs_info, 1);
flush_space(fs_info, space_info, to_reclaim, flush, true);
cond_resched();
spin_lock(&space_info->lock);
}
/* We only went through once, back off our clamping. */
if (loops == 1 && !space_info->reclaim_size)
space_info->clamp = max(1, space_info->clamp - 1);
trace_btrfs_done_preemptive_reclaim(fs_info, space_info);
spin_unlock(&space_info->lock);
}
/*
* FLUSH_DELALLOC_WAIT:
* Space is freed from flushing delalloc in one of two ways.
*
* 1) compression is on and we allocate less space than we reserved
* 2) we are overwriting existing space
*
* For #1 that extra space is reclaimed as soon as the delalloc pages are
* COWed, by way of btrfs_add_reserved_bytes() which adds the actual extent
* length to ->bytes_reserved, and subtracts the reserved space from
* ->bytes_may_use.
*
* For #2 this is trickier. Once the ordered extent runs we will drop the
* extent in the range we are overwriting, which creates a delayed ref for
* that freed extent. This however is not reclaimed until the transaction
* commits, thus the next stages.
*
* RUN_DELAYED_IPUTS
* If we are freeing inodes, we want to make sure all delayed iputs have
* completed, because they could have been on an inode with i_nlink == 0, and
* thus have been truncated and freed up space. But again this space is not
* immediately re-usable, it comes in the form of a delayed ref, which must be
* run and then the transaction must be committed.
*
* COMMIT_TRANS
* This is where we reclaim all of the pinned space generated by running the
* iputs
*
* ALLOC_CHUNK_FORCE
* For data we start with alloc chunk force, however we could have been full
* before, and then the transaction commit could have freed new block groups,
* so if we now have space to allocate do the force chunk allocation.
*/
static const enum btrfs_flush_state data_flush_states[] = {
FLUSH_DELALLOC_FULL,
RUN_DELAYED_IPUTS,
COMMIT_TRANS,
ALLOC_CHUNK_FORCE,
};
static void btrfs_async_reclaim_data_space(struct work_struct *work)
{
struct btrfs_fs_info *fs_info;
struct btrfs_space_info *space_info;
u64 last_tickets_id;
enum btrfs_flush_state flush_state = 0;
fs_info = container_of(work, struct btrfs_fs_info, async_data_reclaim_work);
space_info = fs_info->data_sinfo;
spin_lock(&space_info->lock);
if (list_empty(&space_info->tickets)) {
space_info->flush = 0;
spin_unlock(&space_info->lock);
return;
}
last_tickets_id = space_info->tickets_id;
spin_unlock(&space_info->lock);
while (!space_info->full) {
flush_space(fs_info, space_info, U64_MAX, ALLOC_CHUNK_FORCE, false);
spin_lock(&space_info->lock);
if (list_empty(&space_info->tickets)) {
space_info->flush = 0;
spin_unlock(&space_info->lock);
return;
}
/* Something happened, fail everything and bail. */
if (BTRFS_FS_ERROR(fs_info))
goto aborted_fs;
last_tickets_id = space_info->tickets_id;
spin_unlock(&space_info->lock);
}
while (flush_state < ARRAY_SIZE(data_flush_states)) {
flush_space(fs_info, space_info, U64_MAX,
data_flush_states[flush_state], false);
spin_lock(&space_info->lock);
if (list_empty(&space_info->tickets)) {
space_info->flush = 0;
spin_unlock(&space_info->lock);
return;
}
if (last_tickets_id == space_info->tickets_id) {
flush_state++;
} else {
last_tickets_id = space_info->tickets_id;
flush_state = 0;
}
if (flush_state >= ARRAY_SIZE(data_flush_states)) {
if (space_info->full) {
if (maybe_fail_all_tickets(fs_info, space_info))
flush_state = 0;
else
space_info->flush = 0;
} else {
flush_state = 0;
}
/* Something happened, fail everything and bail. */
if (BTRFS_FS_ERROR(fs_info))
goto aborted_fs;
}
spin_unlock(&space_info->lock);
}
return;
aborted_fs:
maybe_fail_all_tickets(fs_info, space_info);
space_info->flush = 0;
spin_unlock(&space_info->lock);
}
void btrfs_init_async_reclaim_work(struct btrfs_fs_info *fs_info)
{
INIT_WORK(&fs_info->async_reclaim_work, btrfs_async_reclaim_metadata_space);
INIT_WORK(&fs_info->async_data_reclaim_work, btrfs_async_reclaim_data_space);
INIT_WORK(&fs_info->preempt_reclaim_work,
btrfs_preempt_reclaim_metadata_space);
}
static const enum btrfs_flush_state priority_flush_states[] = {
FLUSH_DELAYED_ITEMS_NR,
FLUSH_DELAYED_ITEMS,
ALLOC_CHUNK,
};
static const enum btrfs_flush_state evict_flush_states[] = {
FLUSH_DELAYED_ITEMS_NR,
FLUSH_DELAYED_ITEMS,
FLUSH_DELAYED_REFS_NR,
FLUSH_DELAYED_REFS,
FLUSH_DELALLOC,
FLUSH_DELALLOC_WAIT,
FLUSH_DELALLOC_FULL,
ALLOC_CHUNK,
COMMIT_TRANS,
};
static void priority_reclaim_metadata_space(struct btrfs_fs_info *fs_info,
struct btrfs_space_info *space_info,
struct reserve_ticket *ticket,
const enum btrfs_flush_state *states,
int states_nr)
{
u64 to_reclaim;
int flush_state = 0;
spin_lock(&space_info->lock);
to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info, space_info);
/*
* This is the priority reclaim path, so to_reclaim could be >0 still
* because we may have only satisfied the priority tickets and still
* left non priority tickets on the list. We would then have
* to_reclaim but ->bytes == 0.
*/
if (ticket->bytes == 0) {
spin_unlock(&space_info->lock);
return;
}
while (flush_state < states_nr) {
spin_unlock(&space_info->lock);
flush_space(fs_info, space_info, to_reclaim, states[flush_state],
false);
flush_state++;
spin_lock(&space_info->lock);
if (ticket->bytes == 0) {
spin_unlock(&space_info->lock);
return;
}
}
/*
* Attempt to steal from the global rsv if we can, except if the fs was
* turned into error mode due to a transaction abort when flushing space
* above, in that case fail with the abort error instead of returning
* success to the caller if we can steal from the global rsv - this is
* just to have caller fail immeditelly instead of later when trying to
* modify the fs, making it easier to debug -ENOSPC problems.
*/
if (BTRFS_FS_ERROR(fs_info)) {
ticket->error = BTRFS_FS_ERROR(fs_info);
remove_ticket(space_info, ticket);
} else if (!steal_from_global_rsv(fs_info, space_info, ticket)) {
ticket->error = -ENOSPC;
remove_ticket(space_info, ticket);
}
/*
* We must run try_granting_tickets here because we could be a large
* ticket in front of a smaller ticket that can now be satisfied with
* the available space.
*/
btrfs_try_granting_tickets(fs_info, space_info);
spin_unlock(&space_info->lock);
}
static void priority_reclaim_data_space(struct btrfs_fs_info *fs_info,
struct btrfs_space_info *space_info,
struct reserve_ticket *ticket)
{
spin_lock(&space_info->lock);
/* We could have been granted before we got here. */
if (ticket->bytes == 0) {
spin_unlock(&space_info->lock);
return;
}
while (!space_info->full) {
spin_unlock(&space_info->lock);
flush_space(fs_info, space_info, U64_MAX, ALLOC_CHUNK_FORCE, false);
spin_lock(&space_info->lock);
if (ticket->bytes == 0) {
spin_unlock(&space_info->lock);
return;
}
}
ticket->error = -ENOSPC;
remove_ticket(space_info, ticket);
btrfs_try_granting_tickets(fs_info, space_info);
spin_unlock(&space_info->lock);
}
static void wait_reserve_ticket(struct btrfs_fs_info *fs_info,
struct btrfs_space_info *space_info,
struct reserve_ticket *ticket)
{
DEFINE_WAIT(wait);
int ret = 0;
spin_lock(&space_info->lock);
while (ticket->bytes > 0 && ticket->error == 0) {
ret = prepare_to_wait_event(&ticket->wait, &wait, TASK_KILLABLE);
if (ret) {
/*
* Delete us from the list. After we unlock the space
* info, we don't want the async reclaim job to reserve
* space for this ticket. If that would happen, then the
* ticket's task would not known that space was reserved
* despite getting an error, resulting in a space leak
* (bytes_may_use counter of our space_info).
*/
remove_ticket(space_info, ticket);
ticket->error = -EINTR;
break;
}
spin_unlock(&space_info->lock);
schedule();
finish_wait(&ticket->wait, &wait);
spin_lock(&space_info->lock);
}
spin_unlock(&space_info->lock);
}
/*
* Do the appropriate flushing and waiting for a ticket.
*
* @fs_info: the filesystem
* @space_info: space info for the reservation
* @ticket: ticket for the reservation
* @start_ns: timestamp when the reservation started
* @orig_bytes: amount of bytes originally reserved
* @flush: how much we can flush
*
* This does the work of figuring out how to flush for the ticket, waiting for
* the reservation, and returning the appropriate error if there is one.
*/
static int handle_reserve_ticket(struct btrfs_fs_info *fs_info,
struct btrfs_space_info *space_info,
struct reserve_ticket *ticket,
u64 start_ns, u64 orig_bytes,
enum btrfs_reserve_flush_enum flush)
{
int ret;
switch (flush) {
case BTRFS_RESERVE_FLUSH_DATA:
case BTRFS_RESERVE_FLUSH_ALL:
case BTRFS_RESERVE_FLUSH_ALL_STEAL:
wait_reserve_ticket(fs_info, space_info, ticket);
break;
case BTRFS_RESERVE_FLUSH_LIMIT:
priority_reclaim_metadata_space(fs_info, space_info, ticket,
priority_flush_states,
ARRAY_SIZE(priority_flush_states));
break;
case BTRFS_RESERVE_FLUSH_EVICT:
priority_reclaim_metadata_space(fs_info, space_info, ticket,
evict_flush_states,
ARRAY_SIZE(evict_flush_states));
break;
case BTRFS_RESERVE_FLUSH_FREE_SPACE_INODE:
priority_reclaim_data_space(fs_info, space_info, ticket);
break;
default:
ASSERT(0);
break;
}
ret = ticket->error;
ASSERT(list_empty(&ticket->list));
/*
* Check that we can't have an error set if the reservation succeeded,
* as that would confuse tasks and lead them to error out without
* releasing reserved space (if an error happens the expectation is that
* space wasn't reserved at all).
*/
ASSERT(!(ticket->bytes == 0 && ticket->error));
trace_btrfs_reserve_ticket(fs_info, space_info->flags, orig_bytes,
start_ns, flush, ticket->error);
return ret;
}
/*
* This returns true if this flush state will go through the ordinary flushing
* code.
*/
static inline bool is_normal_flushing(enum btrfs_reserve_flush_enum flush)
{
return (flush == BTRFS_RESERVE_FLUSH_ALL) ||
(flush == BTRFS_RESERVE_FLUSH_ALL_STEAL);
}
static inline void maybe_clamp_preempt(struct btrfs_fs_info *fs_info,
struct btrfs_space_info *space_info)
{
u64 ordered = percpu_counter_sum_positive(&fs_info->ordered_bytes);
u64 delalloc = percpu_counter_sum_positive(&fs_info->delalloc_bytes);
/*
* If we're heavy on ordered operations then clamping won't help us. We
* need to clamp specifically to keep up with dirty'ing buffered
* writers, because there's not a 1:1 correlation of writing delalloc
* and freeing space, like there is with flushing delayed refs or
* delayed nodes. If we're already more ordered than delalloc then
* we're keeping up, otherwise we aren't and should probably clamp.
*/
if (ordered < delalloc)
space_info->clamp = min(space_info->clamp + 1, 8);
}
static inline bool can_steal(enum btrfs_reserve_flush_enum flush)
{
return (flush == BTRFS_RESERVE_FLUSH_ALL_STEAL ||
flush == BTRFS_RESERVE_FLUSH_EVICT);
}
/*
* NO_FLUSH and FLUSH_EMERGENCY don't want to create a ticket, they just want to
* fail as quickly as possible.
*/
static inline bool can_ticket(enum btrfs_reserve_flush_enum flush)
{
return (flush != BTRFS_RESERVE_NO_FLUSH &&
flush != BTRFS_RESERVE_FLUSH_EMERGENCY);
}
/*
* Try to reserve bytes from the block_rsv's space.
*
* @fs_info: the filesystem
* @space_info: space info we want to allocate from
* @orig_bytes: number of bytes we want
* @flush: whether or not we can flush to make our reservation
*
* This will reserve orig_bytes number of bytes from the space info associated
* with the block_rsv. If there is not enough space it will make an attempt to
* flush out space to make room. It will do this by flushing delalloc if
* possible or committing the transaction. If flush is 0 then no attempts to
* regain reservations will be made and this will fail if there is not enough
* space already.
*/
static int __reserve_bytes(struct btrfs_fs_info *fs_info,
struct btrfs_space_info *space_info, u64 orig_bytes,
enum btrfs_reserve_flush_enum flush)
{
struct work_struct *async_work;
struct reserve_ticket ticket;
u64 start_ns = 0;
u64 used;
int ret = -ENOSPC;
bool pending_tickets;
ASSERT(orig_bytes);
/*
* If have a transaction handle (current->journal_info != NULL), then
* the flush method can not be neither BTRFS_RESERVE_FLUSH_ALL* nor
* BTRFS_RESERVE_FLUSH_EVICT, as we could deadlock because those
* flushing methods can trigger transaction commits.
*/
if (current->journal_info) {
/* One assert per line for easier debugging. */
ASSERT(flush != BTRFS_RESERVE_FLUSH_ALL);
ASSERT(flush != BTRFS_RESERVE_FLUSH_ALL_STEAL);
ASSERT(flush != BTRFS_RESERVE_FLUSH_EVICT);
}
if (flush == BTRFS_RESERVE_FLUSH_DATA)
async_work = &fs_info->async_data_reclaim_work;
else
async_work = &fs_info->async_reclaim_work;
spin_lock(&space_info->lock);
used = btrfs_space_info_used(space_info, true);
/*
* We don't want NO_FLUSH allocations to jump everybody, they can
* generally handle ENOSPC in a different way, so treat them the same as
* normal flushers when it comes to skipping pending tickets.
*/
if (is_normal_flushing(flush) || (flush == BTRFS_RESERVE_NO_FLUSH))
pending_tickets = !list_empty(&space_info->tickets) ||
!list_empty(&space_info->priority_tickets);
else
pending_tickets = !list_empty(&space_info->priority_tickets);
/*
* Carry on if we have enough space (short-circuit) OR call
* can_overcommit() to ensure we can overcommit to continue.
*/
if (!pending_tickets &&
((used + orig_bytes <= space_info->total_bytes) ||
btrfs_can_overcommit(fs_info, space_info, orig_bytes, flush))) {
btrfs_space_info_update_bytes_may_use(fs_info, space_info,
orig_bytes);
ret = 0;
}
/*
* Things are dire, we need to make a reservation so we don't abort. We
* will let this reservation go through as long as we have actual space
* left to allocate for the block.
*/
if (ret && unlikely(flush == BTRFS_RESERVE_FLUSH_EMERGENCY)) {
used = btrfs_space_info_used(space_info, false);
if (used + orig_bytes <= space_info->total_bytes) {
btrfs_space_info_update_bytes_may_use(fs_info, space_info,
orig_bytes);
ret = 0;
}
}
/*
* If we couldn't make a reservation then setup our reservation ticket
* and kick the async worker if it's not already running.
*
* If we are a priority flusher then we just need to add our ticket to
* the list and we will do our own flushing further down.
*/
if (ret && can_ticket(flush)) {
ticket.bytes = orig_bytes;
ticket.error = 0;
space_info->reclaim_size += ticket.bytes;
init_waitqueue_head(&ticket.wait);
ticket.steal = can_steal(flush);
if (trace_btrfs_reserve_ticket_enabled())
start_ns = ktime_get_ns();
if (flush == BTRFS_RESERVE_FLUSH_ALL ||
flush == BTRFS_RESERVE_FLUSH_ALL_STEAL ||
flush == BTRFS_RESERVE_FLUSH_DATA) {
list_add_tail(&ticket.list, &space_info->tickets);
if (!space_info->flush) {
/*
* We were forced to add a reserve ticket, so
* our preemptive flushing is unable to keep
* up. Clamp down on the threshold for the
* preemptive flushing in order to keep up with
* the workload.
*/
maybe_clamp_preempt(fs_info, space_info);
space_info->flush = 1;
trace_btrfs_trigger_flush(fs_info,
space_info->flags,
orig_bytes, flush,
"enospc");
queue_work(system_unbound_wq, async_work);
}
} else {
list_add_tail(&ticket.list,
&space_info->priority_tickets);
}
} else if (!ret && space_info->flags & BTRFS_BLOCK_GROUP_METADATA) {
/*
* We will do the space reservation dance during log replay,
* which means we won't have fs_info->fs_root set, so don't do
* the async reclaim as we will panic.
*/
if (!test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags) &&
!work_busy(&fs_info->preempt_reclaim_work) &&
need_preemptive_reclaim(fs_info, space_info)) {
trace_btrfs_trigger_flush(fs_info, space_info->flags,
orig_bytes, flush, "preempt");
queue_work(system_unbound_wq,
&fs_info->preempt_reclaim_work);
}
}
spin_unlock(&space_info->lock);
if (!ret || !can_ticket(flush))
return ret;
return handle_reserve_ticket(fs_info, space_info, &ticket, start_ns,
orig_bytes, flush);
}
/*
* Try to reserve metadata bytes from the block_rsv's space.
*
* @fs_info: the filesystem
* @space_info: the space_info we're allocating for
* @orig_bytes: number of bytes we want
* @flush: whether or not we can flush to make our reservation
*
* This will reserve orig_bytes number of bytes from the space info associated
* with the block_rsv. If there is not enough space it will make an attempt to
* flush out space to make room. It will do this by flushing delalloc if
* possible or committing the transaction. If flush is 0 then no attempts to
* regain reservations will be made and this will fail if there is not enough
* space already.
*/
int btrfs_reserve_metadata_bytes(struct btrfs_fs_info *fs_info,
struct btrfs_space_info *space_info,
u64 orig_bytes,
enum btrfs_reserve_flush_enum flush)
{
int ret;
ret = __reserve_bytes(fs_info, space_info, orig_bytes, flush);
if (ret == -ENOSPC) {
trace_btrfs_space_reservation(fs_info, "space_info:enospc",
space_info->flags, orig_bytes, 1);
if (btrfs_test_opt(fs_info, ENOSPC_DEBUG))
btrfs_dump_space_info(fs_info, space_info, orig_bytes, 0);
}
return ret;
}
/*
* Try to reserve data bytes for an allocation.
*
* @fs_info: the filesystem
* @bytes: number of bytes we need
* @flush: how we are allowed to flush
*
* This will reserve bytes from the data space info. If there is not enough
* space then we will attempt to flush space as specified by flush.
*/
int btrfs_reserve_data_bytes(struct btrfs_fs_info *fs_info, u64 bytes,
enum btrfs_reserve_flush_enum flush)
{
struct btrfs_space_info *data_sinfo = fs_info->data_sinfo;
int ret;
ASSERT(flush == BTRFS_RESERVE_FLUSH_DATA ||
flush == BTRFS_RESERVE_FLUSH_FREE_SPACE_INODE ||
flush == BTRFS_RESERVE_NO_FLUSH);
ASSERT(!current->journal_info || flush != BTRFS_RESERVE_FLUSH_DATA);
ret = __reserve_bytes(fs_info, data_sinfo, bytes, flush);
if (ret == -ENOSPC) {
trace_btrfs_space_reservation(fs_info, "space_info:enospc",
data_sinfo->flags, bytes, 1);
if (btrfs_test_opt(fs_info, ENOSPC_DEBUG))
btrfs_dump_space_info(fs_info, data_sinfo, bytes, 0);
}
return ret;
}
/* Dump all the space infos when we abort a transaction due to ENOSPC. */
__cold void btrfs_dump_space_info_for_trans_abort(struct btrfs_fs_info *fs_info)
{
struct btrfs_space_info *space_info;
btrfs_info(fs_info, "dumping space info:");
list_for_each_entry(space_info, &fs_info->space_info, list) {
spin_lock(&space_info->lock);
__btrfs_dump_space_info(fs_info, space_info);
spin_unlock(&space_info->lock);
}
dump_global_block_rsv(fs_info);
}
/*
* Account the unused space of all the readonly block group in the space_info.
* takes mirrors into account.
*/
u64 btrfs_account_ro_block_groups_free_space(struct btrfs_space_info *sinfo)
{
struct btrfs_block_group *block_group;
u64 free_bytes = 0;
int factor;
/* It's df, we don't care if it's racy */
if (list_empty(&sinfo->ro_bgs))
return 0;
spin_lock(&sinfo->lock);
list_for_each_entry(block_group, &sinfo->ro_bgs, ro_list) {
spin_lock(&block_group->lock);
if (!block_group->ro) {
spin_unlock(&block_group->lock);
continue;
}
factor = btrfs_bg_type_to_factor(block_group->flags);
free_bytes += (block_group->length -
block_group->used) * factor;
spin_unlock(&block_group->lock);
}
spin_unlock(&sinfo->lock);
return free_bytes;
}
static u64 calc_pct_ratio(u64 x, u64 y)
{
int err;
if (!y)
return 0;
again:
err = check_mul_overflow(100, x, &x);
if (err)
goto lose_precision;
return div64_u64(x, y);
lose_precision:
x >>= 10;
y >>= 10;
if (!y)
y = 1;
goto again;
}
/*
* A reasonable buffer for unallocated space is 10 data block_groups.
* If we claw this back repeatedly, we can still achieve efficient
* utilization when near full, and not do too much reclaim while
* always maintaining a solid buffer for workloads that quickly
* allocate and pressure the unallocated space.
*/
static u64 calc_unalloc_target(struct btrfs_fs_info *fs_info)
{
u64 chunk_sz = calc_effective_data_chunk_size(fs_info);
return BTRFS_UNALLOC_BLOCK_GROUP_TARGET * chunk_sz;
}
/*
* The fundamental goal of automatic reclaim is to protect the filesystem's
* unallocated space and thus minimize the probability of the filesystem going
* read only when a metadata allocation failure causes a transaction abort.
*
* However, relocations happen into the space_info's unused space, therefore
* automatic reclaim must also back off as that space runs low. There is no
* value in doing trivial "relocations" of re-writing the same block group
* into a fresh one.
*
* Furthermore, we want to avoid doing too much reclaim even if there are good
* candidates. This is because the allocator is pretty good at filling up the
* holes with writes. So we want to do just enough reclaim to try and stay
* safe from running out of unallocated space but not be wasteful about it.
*
* Therefore, the dynamic reclaim threshold is calculated as follows:
* - calculate a target unallocated amount of 5 block group sized chunks
* - ratchet up the intensity of reclaim depending on how far we are from
* that target by using a formula of unalloc / target to set the threshold.
*
* Typically with 10 block groups as the target, the discrete values this comes
* out to are 0, 10, 20, ... , 80, 90, and 99.
*/
static int calc_dynamic_reclaim_threshold(const struct btrfs_space_info *space_info)
{
struct btrfs_fs_info *fs_info = space_info->fs_info;
u64 unalloc = atomic64_read(&fs_info->free_chunk_space);
u64 target = calc_unalloc_target(fs_info);
u64 alloc = space_info->total_bytes;
u64 used = btrfs_space_info_used(space_info, false);
u64 unused = alloc - used;
u64 want = target > unalloc ? target - unalloc : 0;
u64 data_chunk_size = calc_effective_data_chunk_size(fs_info);
/* If we have no unused space, don't bother, it won't work anyway. */
if (unused < data_chunk_size)
return 0;
/* Cast to int is OK because want <= target. */
return calc_pct_ratio(want, target);
}
int btrfs_calc_reclaim_threshold(const struct btrfs_space_info *space_info)
{
lockdep_assert_held(&space_info->lock);
if (READ_ONCE(space_info->dynamic_reclaim))
return calc_dynamic_reclaim_threshold(space_info);
return READ_ONCE(space_info->bg_reclaim_threshold);
}
/*
* Under "urgent" reclaim, we will reclaim even fresh block groups that have
* recently seen successful allocations, as we are desperate to reclaim
* whatever we can to avoid ENOSPC in a transaction leading to a readonly fs.
*/
static bool is_reclaim_urgent(struct btrfs_space_info *space_info)
{
struct btrfs_fs_info *fs_info = space_info->fs_info;
u64 unalloc = atomic64_read(&fs_info->free_chunk_space);
u64 data_chunk_size = calc_effective_data_chunk_size(fs_info);
return unalloc < data_chunk_size;
}
static void do_reclaim_sweep(const struct btrfs_fs_info *fs_info,
struct btrfs_space_info *space_info, int raid)
{
struct btrfs_block_group *bg;
int thresh_pct;
bool try_again = true;
bool urgent;
spin_lock(&space_info->lock);
urgent = is_reclaim_urgent(space_info);
thresh_pct = btrfs_calc_reclaim_threshold(space_info);
spin_unlock(&space_info->lock);
down_read(&space_info->groups_sem);
again:
list_for_each_entry(bg, &space_info->block_groups[raid], list) {
u64 thresh;
bool reclaim = false;
btrfs_get_block_group(bg);
spin_lock(&bg->lock);
thresh = mult_perc(bg->length, thresh_pct);
if (bg->used < thresh && bg->reclaim_mark) {
try_again = false;
reclaim = true;
}
bg->reclaim_mark++;
spin_unlock(&bg->lock);
if (reclaim)
btrfs_mark_bg_to_reclaim(bg);
btrfs_put_block_group(bg);
}
/*
* In situations where we are very motivated to reclaim (low unalloc)
* use two passes to make the reclaim mark check best effort.
*
* If we have any staler groups, we don't touch the fresher ones, but if we
* really need a block group, do take a fresh one.
*/
if (try_again && urgent) {
try_again = false;
goto again;
}
up_read(&space_info->groups_sem);
}
void btrfs_space_info_update_reclaimable(struct btrfs_space_info *space_info, s64 bytes)
{
u64 chunk_sz = calc_effective_data_chunk_size(space_info->fs_info);
lockdep_assert_held(&space_info->lock);
space_info->reclaimable_bytes += bytes;
if (space_info->reclaimable_bytes >= chunk_sz)
btrfs_set_periodic_reclaim_ready(space_info, true);
}
void btrfs_set_periodic_reclaim_ready(struct btrfs_space_info *space_info, bool ready)
{
lockdep_assert_held(&space_info->lock);
if (!READ_ONCE(space_info->periodic_reclaim))
return;
if (ready != space_info->periodic_reclaim_ready) {
space_info->periodic_reclaim_ready = ready;
if (!ready)
space_info->reclaimable_bytes = 0;
}
}
bool btrfs_should_periodic_reclaim(struct btrfs_space_info *space_info)
{
bool ret;
if (space_info->flags & BTRFS_BLOCK_GROUP_SYSTEM)
return false;
if (!READ_ONCE(space_info->periodic_reclaim))
return false;
spin_lock(&space_info->lock);
ret = space_info->periodic_reclaim_ready;
btrfs_set_periodic_reclaim_ready(space_info, false);
spin_unlock(&space_info->lock);
return ret;
}
void btrfs_reclaim_sweep(const struct btrfs_fs_info *fs_info)
{
int raid;
struct btrfs_space_info *space_info;
list_for_each_entry(space_info, &fs_info->space_info, list) {
if (!btrfs_should_periodic_reclaim(space_info))
continue;
for (raid = 0; raid < BTRFS_NR_RAID_TYPES; raid++)
do_reclaim_sweep(fs_info, space_info, raid);
}
}
Codebase Browser
linux