// SPDX-License-Identifier: GPL-2.0
#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"
/*
* 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
* may_commit_transaction() is the ultimate arbiter on whether we commit the
* transaction or not. In order to avoid constantly churning we do all the
* above flushing first and then commit the transaction as the last resort.
* However we need to take into account things like pinned space that would
* be freed, plus any delayed work we may not have gotten rid of in the case
* of metadata.
*
* FORCE_COMMIT_TRANS
* For use by the preemptive flusher. We use this to bypass the ticketing
* checks in may_commit_transaction, as we have more information about the
* overall state of the system and may want to commit the transaction ahead
* of actual ENOSPC conditions.
*
* 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(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 +
(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;
}
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;
ret = percpu_counter_init(&space_info->total_bytes_pinned, 0,
GFP_KERNEL);
if (ret) {
kfree(space_info);
return ret;
}
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;
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_update_space_info(struct btrfs_fs_info *info, u64 flags,
u64 total_bytes, u64 bytes_used,
u64 bytes_readonly,
struct btrfs_space_info **space_info)
{
struct btrfs_space_info *found;
int factor;
factor = btrfs_bg_type_to_factor(flags);
found = btrfs_find_space_info(info, flags);
ASSERT(found);
spin_lock(&found->lock);
found->total_bytes += total_bytes;
found->disk_total += total_bytes * factor;
found->bytes_used += bytes_used;
found->disk_used += bytes_used * factor;
found->bytes_readonly += bytes_readonly;
if (total_bytes > 0)
found->full = 0;
btrfs_try_granting_tickets(info, found);
spin_unlock(&found->lock);
*space_info = found;
}
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_available_free_space(struct btrfs_fs_info *fs_info,
struct btrfs_space_info *space_info,
enum btrfs_reserve_flush_enum flush)
{
u64 profile;
u64 avail;
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 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;
return avail;
}
int btrfs_can_overcommit(struct btrfs_fs_info *fs_info,
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 satisified 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 void __btrfs_dump_space_info(struct btrfs_fs_info *fs_info,
struct btrfs_space_info *info)
{
lockdep_assert_held(&info->lock);
btrfs_info(fs_info, "space_info %llu has %llu free, is %sfull",
info->flags,
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",
info->total_bytes, info->bytes_used, info->bytes_pinned,
info->bytes_reserved, info->bytes_may_use,
info->bytes_readonly);
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);
}
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;
int index = 0;
spin_lock(&info->lock);
__btrfs_dump_space_info(fs_info, 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) {
spin_lock(&cache->lock);
btrfs_info(fs_info,
"block group %llu has %llu bytes, %llu used %llu pinned %llu reserved %s",
cache->start, cache->length, cache->used, cache->pinned,
cache->reserved, cache->ro ? "[readonly]" : "");
spin_unlock(&cache->lock);
btrfs_dump_free_space(cache, bytes);
}
if (++index < BTRFS_NR_RAID_TYPES)
goto again;
up_read(&info->groups_sem);
}
static inline u64 calc_reclaim_items_nr(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;
}
#define EXTENT_SIZE_PER_ITEM SZ_256K
/*
* 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)
{
struct btrfs_trans_handle *trans;
u64 delalloc_bytes;
u64 ordered_bytes;
u64 items;
long time_left;
int loops;
/* 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, so increase the amount to reclaim by 2x in order to
* make sure we're flushing enough delalloc to hopefully reclaim
* some metadata reservations.
*/
items = calc_reclaim_items_nr(fs_info, to_reclaim) * 2;
to_reclaim = items * EXTENT_SIZE_PER_ITEM;
}
trans = (struct btrfs_trans_handle *)current->journal_info;
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;
/*
* 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)
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);
btrfs_start_delalloc_roots(fs_info, nr_pages, true);
loops++;
if (wait_ordered && !trans) {
btrfs_wait_ordered_roots(fs_info, items, 0, (u64)-1);
} else {
time_left = schedule_timeout_killable(1);
if (time_left)
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);
}
}
/**
* Possibly commit the transaction if its ok to
*
* @fs_info: the filesystem
* @space_info: space_info we are checking for commit, either data or metadata
*
* This will check to make sure that committing the transaction will actually
* get us somewhere and then commit the transaction if it does. Otherwise it
* will return -ENOSPC.
*/
static int may_commit_transaction(struct btrfs_fs_info *fs_info,
struct btrfs_space_info *space_info)
{
struct reserve_ticket *ticket = NULL;
struct btrfs_block_rsv *delayed_rsv = &fs_info->delayed_block_rsv;
struct btrfs_block_rsv *delayed_refs_rsv = &fs_info->delayed_refs_rsv;
struct btrfs_block_rsv *trans_rsv = &fs_info->trans_block_rsv;
struct btrfs_trans_handle *trans;
u64 reclaim_bytes = 0;
u64 bytes_needed = 0;
u64 cur_free_bytes = 0;
trans = (struct btrfs_trans_handle *)current->journal_info;
if (trans)
return -EAGAIN;
spin_lock(&space_info->lock);
cur_free_bytes = btrfs_space_info_used(space_info, true);
if (cur_free_bytes < space_info->total_bytes)
cur_free_bytes = space_info->total_bytes - cur_free_bytes;
else
cur_free_bytes = 0;
if (!list_empty(&space_info->priority_tickets))
ticket = list_first_entry(&space_info->priority_tickets,
struct reserve_ticket, list);
else if (!list_empty(&space_info->tickets))
ticket = list_first_entry(&space_info->tickets,
struct reserve_ticket, list);
if (ticket)
bytes_needed = ticket->bytes;
if (bytes_needed > cur_free_bytes)
bytes_needed -= cur_free_bytes;
else
bytes_needed = 0;
spin_unlock(&space_info->lock);
if (!bytes_needed)
return 0;
trans = btrfs_join_transaction(fs_info->extent_root);
if (IS_ERR(trans))
return PTR_ERR(trans);
/*
* See if there is enough pinned space to make this reservation, or if
* we have block groups that are going to be freed, allowing us to
* possibly do a chunk allocation the next loop through.
*/
if (test_bit(BTRFS_TRANS_HAVE_FREE_BGS, &trans->transaction->flags) ||
__percpu_counter_compare(&space_info->total_bytes_pinned,
bytes_needed,
BTRFS_TOTAL_BYTES_PINNED_BATCH) >= 0)
goto commit;
/*
* See if there is some space in the delayed insertion reserve for this
* reservation. If the space_info's don't match (like for DATA or
* SYSTEM) then just go enospc, reclaiming this space won't recover any
* space to satisfy those reservations.
*/
if (space_info != delayed_rsv->space_info)
goto enospc;
spin_lock(&delayed_rsv->lock);
reclaim_bytes += delayed_rsv->reserved;
spin_unlock(&delayed_rsv->lock);
spin_lock(&delayed_refs_rsv->lock);
reclaim_bytes += delayed_refs_rsv->reserved;
spin_unlock(&delayed_refs_rsv->lock);
spin_lock(&trans_rsv->lock);
reclaim_bytes += trans_rsv->reserved;
spin_unlock(&trans_rsv->lock);
if (reclaim_bytes >= bytes_needed)
goto commit;
bytes_needed -= reclaim_bytes;
if (__percpu_counter_compare(&space_info->total_bytes_pinned,
bytes_needed,
BTRFS_TOTAL_BYTES_PINNED_BATCH) < 0)
goto enospc;
commit:
return btrfs_commit_transaction(trans);
enospc:
btrfs_end_transaction(trans);
return -ENOSPC;
}
/*
* 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->extent_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(root);
if (IS_ERR(trans)) {
ret = PTR_ERR(trans);
break;
}
ret = btrfs_run_delayed_items_nr(trans, nr);
btrfs_end_transaction(trans);
break;
case FLUSH_DELALLOC:
case FLUSH_DELALLOC_WAIT:
shrink_delalloc(fs_info, space_info, num_bytes,
state == FLUSH_DELALLOC_WAIT);
break;
case FLUSH_DELAYED_REFS_NR:
case FLUSH_DELAYED_REFS:
trans = btrfs_join_transaction(root);
if (IS_ERR(trans)) {
ret = PTR_ERR(trans);
break;
}
if (state == FLUSH_DELAYED_REFS_NR)
nr = calc_reclaim_items_nr(fs_info, num_bytes);
else
nr = 0;
btrfs_run_delayed_refs(trans, nr);
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:
ret = may_commit_transaction(fs_info, space_info);
break;
case FORCE_COMMIT_TRANS:
trans = btrfs_join_transaction(root);
if (IS_ERR(trans)) {
ret = PTR_ERR(trans);
break;
}
ret = btrfs_commit_transaction(trans);
break;
default:
ret = -ENOSPC;
break;
}
trace_btrfs_flush_space(fs_info, space_info->flags, num_bytes, state,
ret, for_preempt);
return;
}
static inline u64
btrfs_calc_reclaim_metadata_size(struct btrfs_fs_info *fs_info,
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,
struct btrfs_space_info *space_info)
{
u64 ordered, delalloc;
u64 thresh = div_factor_fine(space_info->total_bytes, 98);
u64 used;
/* If we're just plain full then async reclaim just slows us down. */
if ((space_info->bytes_used + space_info->bytes_reserved) >= thresh)
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);
thresh += (space_info->total_bytes - space_info->bytes_used -
space_info->bytes_reserved - space_info->bytes_readonly);
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.
*/
ordered = percpu_counter_sum_positive(&fs_info->ordered_bytes);
delalloc = percpu_counter_sum_positive(&fs_info->delalloc_bytes);
if (ordered >= delalloc)
used += fs_info->delayed_refs_rsv.reserved +
fs_info->delayed_block_rsv.reserved;
else
used += space_info->bytes_may_use;
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 (global_rsv->space_info != space_info)
return false;
spin_lock(&global_rsv->lock);
min_bytes = div_factor(global_rsv->size, 1);
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;
}
/*
* maybe_fail_all_tickets - 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;
u64 first_ticket_bytes = 0;
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 (ticket->steal &&
steal_from_global_rsv(fs_info, space_info, ticket))
return true;
/*
* may_commit_transaction will avoid committing the transaction
* if it doesn't feel like the space reclaimed by the commit
* would result in the ticket succeeding. However if we have a
* smaller ticket in the queue it may be small enough to be
* satisified by committing the transaction, so if any
* subsequent ticket is smaller than the first ticket go ahead
* and send us back for another loop through the enospc flushing
* code.
*/
if (first_ticket_bytes == 0)
first_ticket_bytes = ticket->bytes;
else if (first_ticket_bytes > ticket->bytes)
return true;
if (btrfs_test_opt(fs_info, ENOSPC_DEBUG))
btrfs_info(fs_info, "failing ticket with %llu bytes",
ticket->bytes);
remove_ticket(space_info, ticket);
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.
*/
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 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;
u64 global_rsv_size = global_rsv->reserved;
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 +
delayed_block_rsv->reserved +
delayed_refs_rsv->reserved +
trans_rsv->reserved;
if (block_rsv_size < space_info->bytes_may_use)
delalloc_size = space_info->bytes_may_use - block_rsv_size;
spin_unlock(&space_info->lock);
/*
* 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 >
(delayed_block_rsv->reserved +
delayed_refs_rsv->reserved)) {
to_reclaim = space_info->bytes_pinned;
flush = FORCE_COMMIT_TRANS;
} else if (delayed_block_rsv->reserved >
delayed_refs_rsv->reserved) {
to_reclaim = delayed_block_rsv->reserved;
flush = FLUSH_DELAYED_ITEMS_NR;
} else {
to_reclaim = delayed_refs_rsv->reserved;
flush = FLUSH_DELAYED_REFS_NR;
}
/*
* 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);
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.
*
* FLUSH_DELAYED_REFS
* The above two cases generate delayed refs that will affect
* ->total_bytes_pinned. However this counter can be inconsistent with
* reality if there are outstanding delayed refs. This is because we adjust
* the counter based solely on the current set of delayed refs and disregard
* any on-disk state which might include more refs. So for example, if we
* have an extent with 2 references, but we only drop 1, we'll see that there
* is a negative delayed ref count for the extent and assume that the space
* will be freed, and thus increase ->total_bytes_pinned.
*
* Running the delayed refs gives us the actual real view of what will be
* freed at the transaction commit time. This stage will not actually free
* space for us, it just makes sure that may_commit_transaction() has all of
* the information it needs to make the right decision.
*
* COMMIT_TRANS
* This is where we reclaim all of the pinned space generated by the previous
* two stages. We will not commit the transaction if we don't think we're
* likely to satisfy our request, which means if our current free space +
* total_bytes_pinned < reservation we will not commit. This is why the
* previous states are actually important, to make sure we know for sure
* whether committing the transaction will allow us to make progress.
*
* 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_WAIT,
RUN_DELAYED_IPUTS,
FLUSH_DELAYED_REFS,
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;
}
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;
}
}
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,
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;
spin_lock(&space_info->lock);
to_reclaim = btrfs_calc_reclaim_metadata_size(fs_info, space_info);
if (!to_reclaim) {
spin_unlock(&space_info->lock);
return;
}
spin_unlock(&space_info->lock);
flush_state = 0;
do {
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;
}
spin_unlock(&space_info->lock);
} while (flush_state < states_nr);
}
static void priority_reclaim_data_space(struct btrfs_fs_info *fs_info,
struct btrfs_space_info *space_info,
struct reserve_ticket *ticket)
{
while (!space_info->full) {
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;
}
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;
}
spin_lock(&space_info->lock);
ret = ticket->error;
if (ticket->bytes || ticket->error) {
/*
* We were a priority ticket, so we need to delete ourselves
* from the list. Because we could have other priority tickets
* behind us that require less space, run
* btrfs_try_granting_tickets() to see if their reservations can
* now be made.
*/
if (!list_empty(&ticket->list)) {
remove_ticket(space_info, ticket);
btrfs_try_granting_tickets(fs_info, space_info);
}
if (!ret)
ret = -ENOSPC;
}
spin_unlock(&space_info->lock);
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);
}
/**
* 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 = 0;
bool pending_tickets;
ASSERT(orig_bytes);
ASSERT(!current->journal_info || flush != BTRFS_RESERVE_FLUSH_ALL);
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);
ret = -ENOSPC;
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;
}
/*
* 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 && flush != BTRFS_RESERVE_NO_FLUSH) {
ticket.bytes = orig_bytes;
ticket.error = 0;
space_info->reclaim_size += ticket.bytes;
init_waitqueue_head(&ticket.wait);
ticket.steal = (flush == BTRFS_RESERVE_FLUSH_ALL_STEAL);
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) {
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);
}
/*
* 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);
} else if (!ret && space_info->flags & BTRFS_BLOCK_GROUP_METADATA) {
used += orig_bytes;
/*
* 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) &&
need_preemptive_reclaim(fs_info, space_info) &&
!work_busy(&fs_info->preempt_reclaim_work)) {
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 || flush == BTRFS_RESERVE_NO_FLUSH)
return ret;
return handle_reserve_ticket(fs_info, space_info, &ticket, start_ns,
orig_bytes, flush);
}
/**
* Trye to reserve metadata bytes from the block_rsv's space
*
* @root: the root we're allocating for
* @block_rsv: block_rsv 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_root *root,
struct btrfs_block_rsv *block_rsv,
u64 orig_bytes,
enum btrfs_reserve_flush_enum flush)
{
struct btrfs_fs_info *fs_info = root->fs_info;
struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
int ret;
ret = __reserve_bytes(fs_info, block_rsv->space_info, orig_bytes, flush);
if (ret == -ENOSPC &&
unlikely(root->orphan_cleanup_state == ORPHAN_CLEANUP_STARTED)) {
if (block_rsv != global_rsv &&
!btrfs_block_rsv_use_bytes(global_rsv, orig_bytes))
ret = 0;
}
if (ret == -ENOSPC) {
trace_btrfs_space_reservation(fs_info, "space_info:enospc",
block_rsv->space_info->flags,
orig_bytes, 1);
if (btrfs_test_opt(fs_info, ENOSPC_DEBUG))
btrfs_dump_space_info(fs_info, block_rsv->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);
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;
}
