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android-kvm / linux / 019947805a8d703fbb57d607187ff1148bb267ff / . / fs / btrfs / block-group.c
blob: 378d9103a2072b1628e66d850a42b9254be72b36 [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0
#include <linux/sizes.h>
#include <linux/list_sort.h>
#include "misc.h"
#include "ctree.h"
#include "block-group.h"
#include "space-info.h"
#include "disk-io.h"
#include "free-space-cache.h"
#include "free-space-tree.h"
#include "volumes.h"
#include "transaction.h"
#include "ref-verify.h"
#include "sysfs.h"
#include "tree-log.h"
#include "delalloc-space.h"
#include "discard.h"
#include "raid56.h"
#include "zoned.h"
#include "fs.h"
#include "accessors.h"
#include "extent-tree.h"
#ifdef CONFIG_BTRFS_DEBUG
int btrfs_should_fragment_free_space(struct btrfs_block_group *block_group)
{
struct btrfs_fs_info *fs_info = block_group->fs_info;
return (btrfs_test_opt(fs_info, FRAGMENT_METADATA) &&
block_group->flags & BTRFS_BLOCK_GROUP_METADATA) ||
(btrfs_test_opt(fs_info, FRAGMENT_DATA) &&
block_group->flags & BTRFS_BLOCK_GROUP_DATA);
}
#endif
/*
* Return target flags in extended format or 0 if restripe for this chunk_type
* is not in progress
*
* Should be called with balance_lock held
*/
static u64 get_restripe_target(struct btrfs_fs_info *fs_info, u64 flags)
{
struct btrfs_balance_control *bctl = fs_info->balance_ctl;
u64 target = 0;
if (!bctl)
return 0;
if (flags & BTRFS_BLOCK_GROUP_DATA &&
bctl->data.flags & BTRFS_BALANCE_ARGS_CONVERT) {
target = BTRFS_BLOCK_GROUP_DATA | bctl->data.target;
} else if (flags & BTRFS_BLOCK_GROUP_SYSTEM &&
bctl->sys.flags & BTRFS_BALANCE_ARGS_CONVERT) {
target = BTRFS_BLOCK_GROUP_SYSTEM | bctl->sys.target;
} else if (flags & BTRFS_BLOCK_GROUP_METADATA &&
bctl->meta.flags & BTRFS_BALANCE_ARGS_CONVERT) {
target = BTRFS_BLOCK_GROUP_METADATA | bctl->meta.target;
}
return target;
}
/*
* @flags: available profiles in extended format (see ctree.h)
*
* Return reduced profile in chunk format. If profile changing is in progress
* (either running or paused) picks the target profile (if it's already
* available), otherwise falls back to plain reducing.
*/
static u64 btrfs_reduce_alloc_profile(struct btrfs_fs_info *fs_info, u64 flags)
{
u64 num_devices = fs_info->fs_devices->rw_devices;
u64 target;
u64 raid_type;
u64 allowed = 0;
/*
* See if restripe for this chunk_type is in progress, if so try to
* reduce to the target profile
*/
spin_lock(&fs_info->balance_lock);
target = get_restripe_target(fs_info, flags);
if (target) {
spin_unlock(&fs_info->balance_lock);
return extended_to_chunk(target);
}
spin_unlock(&fs_info->balance_lock);
/* First, mask out the RAID levels which aren't possible */
for (raid_type = 0; raid_type < BTRFS_NR_RAID_TYPES; raid_type++) {
if (num_devices >= btrfs_raid_array[raid_type].devs_min)
allowed |= btrfs_raid_array[raid_type].bg_flag;
}
allowed &= flags;
/* Select the highest-redundancy RAID level. */
if (allowed & BTRFS_BLOCK_GROUP_RAID1C4)
allowed = BTRFS_BLOCK_GROUP_RAID1C4;
else if (allowed & BTRFS_BLOCK_GROUP_RAID6)
allowed = BTRFS_BLOCK_GROUP_RAID6;
else if (allowed & BTRFS_BLOCK_GROUP_RAID1C3)
allowed = BTRFS_BLOCK_GROUP_RAID1C3;
else if (allowed & BTRFS_BLOCK_GROUP_RAID5)
allowed = BTRFS_BLOCK_GROUP_RAID5;
else if (allowed & BTRFS_BLOCK_GROUP_RAID10)
allowed = BTRFS_BLOCK_GROUP_RAID10;
else if (allowed & BTRFS_BLOCK_GROUP_RAID1)
allowed = BTRFS_BLOCK_GROUP_RAID1;
else if (allowed & BTRFS_BLOCK_GROUP_DUP)
allowed = BTRFS_BLOCK_GROUP_DUP;
else if (allowed & BTRFS_BLOCK_GROUP_RAID0)
allowed = BTRFS_BLOCK_GROUP_RAID0;
flags &= ~BTRFS_BLOCK_GROUP_PROFILE_MASK;
return extended_to_chunk(flags | allowed);
}
u64 btrfs_get_alloc_profile(struct btrfs_fs_info *fs_info, u64 orig_flags)
{
unsigned seq;
u64 flags;
do {
flags = orig_flags;
seq = read_seqbegin(&fs_info->profiles_lock);
if (flags & BTRFS_BLOCK_GROUP_DATA)
flags |= fs_info->avail_data_alloc_bits;
else if (flags & BTRFS_BLOCK_GROUP_SYSTEM)
flags |= fs_info->avail_system_alloc_bits;
else if (flags & BTRFS_BLOCK_GROUP_METADATA)
flags |= fs_info->avail_metadata_alloc_bits;
} while (read_seqretry(&fs_info->profiles_lock, seq));
return btrfs_reduce_alloc_profile(fs_info, flags);
}
void btrfs_get_block_group(struct btrfs_block_group *cache)
{
refcount_inc(&cache->refs);
}
void btrfs_put_block_group(struct btrfs_block_group *cache)
{
if (refcount_dec_and_test(&cache->refs)) {
WARN_ON(cache->pinned > 0);
/*
* If there was a failure to cleanup a log tree, very likely due
* to an IO failure on a writeback attempt of one or more of its
* extent buffers, we could not do proper (and cheap) unaccounting
* of their reserved space, so don't warn on reserved > 0 in that
* case.
*/
if (!(cache->flags & BTRFS_BLOCK_GROUP_METADATA) ||
!BTRFS_FS_LOG_CLEANUP_ERROR(cache->fs_info))
WARN_ON(cache->reserved > 0);
/*
* A block_group shouldn't be on the discard_list anymore.
* Remove the block_group from the discard_list to prevent us
* from causing a panic due to NULL pointer dereference.
*/
if (WARN_ON(!list_empty(&cache->discard_list)))
btrfs_discard_cancel_work(&cache->fs_info->discard_ctl,
cache);
kfree(cache->free_space_ctl);
btrfs_free_chunk_map(cache->physical_map);
kfree(cache);
}
}
/*
* This adds the block group to the fs_info rb tree for the block group cache
*/
static int btrfs_add_block_group_cache(struct btrfs_fs_info *info,
struct btrfs_block_group *block_group)
{
struct rb_node **p;
struct rb_node *parent = NULL;
struct btrfs_block_group *cache;
bool leftmost = true;
ASSERT(block_group->length != 0);
write_lock(&info->block_group_cache_lock);
p = &info->block_group_cache_tree.rb_root.rb_node;
while (*p) {
parent = *p;
cache = rb_entry(parent, struct btrfs_block_group, cache_node);
if (block_group->start < cache->start) {
p = &(*p)->rb_left;
} else if (block_group->start > cache->start) {
p = &(*p)->rb_right;
leftmost = false;
} else {
write_unlock(&info->block_group_cache_lock);
return -EEXIST;
}
}
rb_link_node(&block_group->cache_node, parent, p);
rb_insert_color_cached(&block_group->cache_node,
&info->block_group_cache_tree, leftmost);
write_unlock(&info->block_group_cache_lock);
return 0;
}
/*
* This will return the block group at or after bytenr if contains is 0, else
* it will return the block group that contains the bytenr
*/
static struct btrfs_block_group *block_group_cache_tree_search(
struct btrfs_fs_info *info, u64 bytenr, int contains)
{
struct btrfs_block_group *cache, *ret = NULL;
struct rb_node *n;
u64 end, start;
read_lock(&info->block_group_cache_lock);
n = info->block_group_cache_tree.rb_root.rb_node;
while (n) {
cache = rb_entry(n, struct btrfs_block_group, cache_node);
end = cache->start + cache->length - 1;
start = cache->start;
if (bytenr < start) {
if (!contains && (!ret || start < ret->start))
ret = cache;
n = n->rb_left;
} else if (bytenr > start) {
if (contains && bytenr <= end) {
ret = cache;
break;
}
n = n->rb_right;
} else {
ret = cache;
break;
}
}
if (ret)
btrfs_get_block_group(ret);
read_unlock(&info->block_group_cache_lock);
return ret;
}
/*
* Return the block group that starts at or after bytenr
*/
struct btrfs_block_group *btrfs_lookup_first_block_group(
struct btrfs_fs_info *info, u64 bytenr)
{
return block_group_cache_tree_search(info, bytenr, 0);
}
/*
* Return the block group that contains the given bytenr
*/
struct btrfs_block_group *btrfs_lookup_block_group(
struct btrfs_fs_info *info, u64 bytenr)
{
return block_group_cache_tree_search(info, bytenr, 1);
}
struct btrfs_block_group *btrfs_next_block_group(
struct btrfs_block_group *cache)
{
struct btrfs_fs_info *fs_info = cache->fs_info;
struct rb_node *node;
read_lock(&fs_info->block_group_cache_lock);
/* If our block group was removed, we need a full search. */
if (RB_EMPTY_NODE(&cache->cache_node)) {
const u64 next_bytenr = cache->start + cache->length;
read_unlock(&fs_info->block_group_cache_lock);
btrfs_put_block_group(cache);
return btrfs_lookup_first_block_group(fs_info, next_bytenr);
}
node = rb_next(&cache->cache_node);
btrfs_put_block_group(cache);
if (node) {
cache = rb_entry(node, struct btrfs_block_group, cache_node);
btrfs_get_block_group(cache);
} else
cache = NULL;
read_unlock(&fs_info->block_group_cache_lock);
return cache;
}
/*
* Check if we can do a NOCOW write for a given extent.
*
* @fs_info: The filesystem information object.
* @bytenr: Logical start address of the extent.
*
* Check if we can do a NOCOW write for the given extent, and increments the
* number of NOCOW writers in the block group that contains the extent, as long
* as the block group exists and it's currently not in read-only mode.
*
* Returns: A non-NULL block group pointer if we can do a NOCOW write, the caller
* is responsible for calling btrfs_dec_nocow_writers() later.
*
* Or NULL if we can not do a NOCOW write
*/
struct btrfs_block_group *btrfs_inc_nocow_writers(struct btrfs_fs_info *fs_info,
u64 bytenr)
{
struct btrfs_block_group *bg;
bool can_nocow = true;
bg = btrfs_lookup_block_group(fs_info, bytenr);
if (!bg)
return NULL;
spin_lock(&bg->lock);
if (bg->ro)
can_nocow = false;
else
atomic_inc(&bg->nocow_writers);
spin_unlock(&bg->lock);
if (!can_nocow) {
btrfs_put_block_group(bg);
return NULL;
}
/* No put on block group, done by btrfs_dec_nocow_writers(). */
return bg;
}
/*
* Decrement the number of NOCOW writers in a block group.
*
* This is meant to be called after a previous call to btrfs_inc_nocow_writers(),
* and on the block group returned by that call. Typically this is called after
* creating an ordered extent for a NOCOW write, to prevent races with scrub and
* relocation.
*
* After this call, the caller should not use the block group anymore. It it wants
* to use it, then it should get a reference on it before calling this function.
*/
void btrfs_dec_nocow_writers(struct btrfs_block_group *bg)
{
if (atomic_dec_and_test(&bg->nocow_writers))
wake_up_var(&bg->nocow_writers);
/* For the lookup done by a previous call to btrfs_inc_nocow_writers(). */
btrfs_put_block_group(bg);
}
void btrfs_wait_nocow_writers(struct btrfs_block_group *bg)
{
wait_var_event(&bg->nocow_writers, !atomic_read(&bg->nocow_writers));
}
void btrfs_dec_block_group_reservations(struct btrfs_fs_info *fs_info,
const u64 start)
{
struct btrfs_block_group *bg;
bg = btrfs_lookup_block_group(fs_info, start);
ASSERT(bg);
if (atomic_dec_and_test(&bg->reservations))
wake_up_var(&bg->reservations);
btrfs_put_block_group(bg);
}
void btrfs_wait_block_group_reservations(struct btrfs_block_group *bg)
{
struct btrfs_space_info *space_info = bg->space_info;
ASSERT(bg->ro);
if (!(bg->flags & BTRFS_BLOCK_GROUP_DATA))
return;
/*
* Our block group is read only but before we set it to read only,
* some task might have had allocated an extent from it already, but it
* has not yet created a respective ordered extent (and added it to a
* root's list of ordered extents).
* Therefore wait for any task currently allocating extents, since the
* block group's reservations counter is incremented while a read lock
* on the groups' semaphore is held and decremented after releasing
* the read access on that semaphore and creating the ordered extent.
*/
down_write(&space_info->groups_sem);
up_write(&space_info->groups_sem);
wait_var_event(&bg->reservations, !atomic_read(&bg->reservations));
}
struct btrfs_caching_control *btrfs_get_caching_control(
struct btrfs_block_group *cache)
{
struct btrfs_caching_control *ctl;
spin_lock(&cache->lock);
if (!cache->caching_ctl) {
spin_unlock(&cache->lock);
return NULL;
}
ctl = cache->caching_ctl;
refcount_inc(&ctl->count);
spin_unlock(&cache->lock);
return ctl;
}
void btrfs_put_caching_control(struct btrfs_caching_control *ctl)
{
if (refcount_dec_and_test(&ctl->count))
kfree(ctl);
}
/*
* When we wait for progress in the block group caching, its because our
* allocation attempt failed at least once. So, we must sleep and let some
* progress happen before we try again.
*
* This function will sleep at least once waiting for new free space to show
* up, and then it will check the block group free space numbers for our min
* num_bytes. Another option is to have it go ahead and look in the rbtree for
* a free extent of a given size, but this is a good start.
*
* Callers of this must check if cache->cached == BTRFS_CACHE_ERROR before using
* any of the information in this block group.
*/
void btrfs_wait_block_group_cache_progress(struct btrfs_block_group *cache,
u64 num_bytes)
{
struct btrfs_caching_control *caching_ctl;
int progress;
caching_ctl = btrfs_get_caching_control(cache);
if (!caching_ctl)
return;
/*
* We've already failed to allocate from this block group, so even if
* there's enough space in the block group it isn't contiguous enough to
* allow for an allocation, so wait for at least the next wakeup tick,
* or for the thing to be done.
*/
progress = atomic_read(&caching_ctl->progress);
wait_event(caching_ctl->wait, btrfs_block_group_done(cache) ||
(progress != atomic_read(&caching_ctl->progress) &&
(cache->free_space_ctl->free_space >= num_bytes)));
btrfs_put_caching_control(caching_ctl);
}
static int btrfs_caching_ctl_wait_done(struct btrfs_block_group *cache,
struct btrfs_caching_control *caching_ctl)
{
wait_event(caching_ctl->wait, btrfs_block_group_done(cache));
return cache->cached == BTRFS_CACHE_ERROR ? -EIO : 0;
}
static int btrfs_wait_block_group_cache_done(struct btrfs_block_group *cache)
{
struct btrfs_caching_control *caching_ctl;
int ret;
caching_ctl = btrfs_get_caching_control(cache);
if (!caching_ctl)
return (cache->cached == BTRFS_CACHE_ERROR) ? -EIO : 0;
ret = btrfs_caching_ctl_wait_done(cache, caching_ctl);
btrfs_put_caching_control(caching_ctl);
return ret;
}
#ifdef CONFIG_BTRFS_DEBUG
static void fragment_free_space(struct btrfs_block_group *block_group)
{
struct btrfs_fs_info *fs_info = block_group->fs_info;
u64 start = block_group->start;
u64 len = block_group->length;
u64 chunk = block_group->flags & BTRFS_BLOCK_GROUP_METADATA ?
fs_info->nodesize : fs_info->sectorsize;
u64 step = chunk << 1;
while (len > chunk) {
btrfs_remove_free_space(block_group, start, chunk);
start += step;
if (len < step)
len = 0;
else
len -= step;
}
}
#endif
/*
* Add a free space range to the in memory free space cache of a block group.
* This checks if the range contains super block locations and any such
* locations are not added to the free space cache.
*
* @block_group: The target block group.
* @start: Start offset of the range.
* @end: End offset of the range (exclusive).
* @total_added_ret: Optional pointer to return the total amount of space
* added to the block group's free space cache.
*
* Returns 0 on success or < 0 on error.
*/
int btrfs_add_new_free_space(struct btrfs_block_group *block_group, u64 start,
u64 end, u64 *total_added_ret)
{
struct btrfs_fs_info *info = block_group->fs_info;
u64 extent_start, extent_end, size;
int ret;
if (total_added_ret)
*total_added_ret = 0;
while (start < end) {
if (!find_first_extent_bit(&info->excluded_extents, start,
&extent_start, &extent_end,
EXTENT_DIRTY | EXTENT_UPTODATE,
NULL))
break;
if (extent_start <= start) {
start = extent_end + 1;
} else if (extent_start > start && extent_start < end) {
size = extent_start - start;
ret = btrfs_add_free_space_async_trimmed(block_group,
start, size);
if (ret)
return ret;
if (total_added_ret)
*total_added_ret += size;
start = extent_end + 1;
} else {
break;
}
}
if (start < end) {
size = end - start;
ret = btrfs_add_free_space_async_trimmed(block_group, start,
size);
if (ret)
return ret;
if (total_added_ret)
*total_added_ret += size;
}
return 0;
}
/*
* Get an arbitrary extent item index / max_index through the block group
*
* @block_group the block group to sample from
* @index: the integral step through the block group to grab from
* @max_index: the granularity of the sampling
* @key: return value parameter for the item we find
*
* Pre-conditions on indices:
* 0 <= index <= max_index
* 0 < max_index
*
* Returns: 0 on success, 1 if the search didn't yield a useful item, negative
* error code on error.
*/
static int sample_block_group_extent_item(struct btrfs_caching_control *caching_ctl,
struct btrfs_block_group *block_group,
int index, int max_index,
struct btrfs_key *found_key)
{
struct btrfs_fs_info *fs_info = block_group->fs_info;
struct btrfs_root *extent_root;
u64 search_offset;
u64 search_end = block_group->start + block_group->length;
struct btrfs_path *path;
struct btrfs_key search_key;
int ret = 0;
ASSERT(index >= 0);
ASSERT(index <= max_index);
ASSERT(max_index > 0);
lockdep_assert_held(&caching_ctl->mutex);
lockdep_assert_held_read(&fs_info->commit_root_sem);
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
extent_root = btrfs_extent_root(fs_info, max_t(u64, block_group->start,
BTRFS_SUPER_INFO_OFFSET));
path->skip_locking = 1;
path->search_commit_root = 1;
path->reada = READA_FORWARD;
search_offset = index * div_u64(block_group->length, max_index);
search_key.objectid = block_group->start + search_offset;
search_key.type = BTRFS_EXTENT_ITEM_KEY;
search_key.offset = 0;
btrfs_for_each_slot(extent_root, &search_key, found_key, path, ret) {
/* Success; sampled an extent item in the block group */
if (found_key->type == BTRFS_EXTENT_ITEM_KEY &&
found_key->objectid >= block_group->start &&
found_key->objectid + found_key->offset <= search_end)
break;
/* We can't possibly find a valid extent item anymore */
if (found_key->objectid >= search_end) {
ret = 1;
break;
}
}
lockdep_assert_held(&caching_ctl->mutex);
lockdep_assert_held_read(&fs_info->commit_root_sem);
btrfs_free_path(path);
return ret;
}
/*
* Best effort attempt to compute a block group's size class while caching it.
*
* @block_group: the block group we are caching
*
* We cannot infer the size class while adding free space extents, because that
* logic doesn't care about contiguous file extents (it doesn't differentiate
* between a 100M extent and 100 contiguous 1M extents). So we need to read the
* file extent items. Reading all of them is quite wasteful, because usually
* only a handful are enough to give a good answer. Therefore, we just grab 5 of
* them at even steps through the block group and pick the smallest size class
* we see. Since size class is best effort, and not guaranteed in general,
* inaccuracy is acceptable.
*
* To be more explicit about why this algorithm makes sense:
*
* If we are caching in a block group from disk, then there are three major cases
* to consider:
* 1. the block group is well behaved and all extents in it are the same size
* class.
* 2. the block group is mostly one size class with rare exceptions for last
* ditch allocations
* 3. the block group was populated before size classes and can have a totally
* arbitrary mix of size classes.
*
* In case 1, looking at any extent in the block group will yield the correct
* result. For the mixed cases, taking the minimum size class seems like a good
* approximation, since gaps from frees will be usable to the size class. For
* 2., a small handful of file extents is likely to yield the right answer. For
* 3, we can either read every file extent, or admit that this is best effort
* anyway and try to stay fast.
*
* Returns: 0 on success, negative error code on error.
*/
static int load_block_group_size_class(struct btrfs_caching_control *caching_ctl,
struct btrfs_block_group *block_group)
{
struct btrfs_fs_info *fs_info = block_group->fs_info;
struct btrfs_key key;
int i;
u64 min_size = block_group->length;
enum btrfs_block_group_size_class size_class = BTRFS_BG_SZ_NONE;
int ret;
if (!btrfs_block_group_should_use_size_class(block_group))
return 0;
lockdep_assert_held(&caching_ctl->mutex);
lockdep_assert_held_read(&fs_info->commit_root_sem);
for (i = 0; i < 5; ++i) {
ret = sample_block_group_extent_item(caching_ctl, block_group, i, 5, &key);
if (ret < 0)
goto out;
if (ret > 0)
continue;
min_size = min_t(u64, min_size, key.offset);
size_class = btrfs_calc_block_group_size_class(min_size);
}
if (size_class != BTRFS_BG_SZ_NONE) {
spin_lock(&block_group->lock);
block_group->size_class = size_class;
spin_unlock(&block_group->lock);
}
out:
return ret;
}
static int load_extent_tree_free(struct btrfs_caching_control *caching_ctl)
{
struct btrfs_block_group *block_group = caching_ctl->block_group;
struct btrfs_fs_info *fs_info = block_group->fs_info;
struct btrfs_root *extent_root;
struct btrfs_path *path;
struct extent_buffer *leaf;
struct btrfs_key key;
u64 total_found = 0;
u64 last = 0;
u32 nritems;
int ret;
bool wakeup = true;
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
last = max_t(u64, block_group->start, BTRFS_SUPER_INFO_OFFSET);
extent_root = btrfs_extent_root(fs_info, last);
#ifdef CONFIG_BTRFS_DEBUG
/*
* If we're fragmenting we don't want to make anybody think we can
* allocate from this block group until we've had a chance to fragment
* the free space.
*/
if (btrfs_should_fragment_free_space(block_group))
wakeup = false;
#endif
/*
* We don't want to deadlock with somebody trying to allocate a new
* extent for the extent root while also trying to search the extent
* root to add free space. So we skip locking and search the commit
* root, since its read-only
*/
path->skip_locking = 1;
path->search_commit_root = 1;
path->reada = READA_FORWARD;
key.objectid = last;
key.offset = 0;
key.type = BTRFS_EXTENT_ITEM_KEY;
next:
ret = btrfs_search_slot(NULL, extent_root, &key, path, 0, 0);
if (ret < 0)
goto out;
leaf = path->nodes[0];
nritems = btrfs_header_nritems(leaf);
while (1) {
if (btrfs_fs_closing(fs_info) > 1) {
last = (u64)-1;
break;
}
if (path->slots[0] < nritems) {
btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
} else {
ret = btrfs_find_next_key(extent_root, path, &key, 0, 0);
if (ret)
break;
if (need_resched() ||
rwsem_is_contended(&fs_info->commit_root_sem)) {
btrfs_release_path(path);
up_read(&fs_info->commit_root_sem);
mutex_unlock(&caching_ctl->mutex);
cond_resched();
mutex_lock(&caching_ctl->mutex);
down_read(&fs_info->commit_root_sem);
goto next;
}
ret = btrfs_next_leaf(extent_root, path);
if (ret < 0)
goto out;
if (ret)
break;
leaf = path->nodes[0];
nritems = btrfs_header_nritems(leaf);
continue;
}
if (key.objectid < last) {
key.objectid = last;
key.offset = 0;
key.type = BTRFS_EXTENT_ITEM_KEY;
btrfs_release_path(path);
goto next;
}
if (key.objectid < block_group->start) {
path->slots[0]++;
continue;
}
if (key.objectid >= block_group->start + block_group->length)
break;
if (key.type == BTRFS_EXTENT_ITEM_KEY ||
key.type == BTRFS_METADATA_ITEM_KEY) {
u64 space_added;
ret = btrfs_add_new_free_space(block_group, last,
key.objectid, &space_added);
if (ret)
goto out;
total_found += space_added;
if (key.type == BTRFS_METADATA_ITEM_KEY)
last = key.objectid +
fs_info->nodesize;
else
last = key.objectid + key.offset;
if (total_found > CACHING_CTL_WAKE_UP) {
total_found = 0;
if (wakeup) {
atomic_inc(&caching_ctl->progress);
wake_up(&caching_ctl->wait);
}
}
}
path->slots[0]++;
}
ret = btrfs_add_new_free_space(block_group, last,
block_group->start + block_group->length,
NULL);
out:
btrfs_free_path(path);
return ret;
}
static inline void btrfs_free_excluded_extents(const struct btrfs_block_group *bg)
{
clear_extent_bits(&bg->fs_info->excluded_extents, bg->start,
bg->start + bg->length - 1, EXTENT_UPTODATE);
}
static noinline void caching_thread(struct btrfs_work *work)
{
struct btrfs_block_group *block_group;
struct btrfs_fs_info *fs_info;
struct btrfs_caching_control *caching_ctl;
int ret;
caching_ctl = container_of(work, struct btrfs_caching_control, work);
block_group = caching_ctl->block_group;
fs_info = block_group->fs_info;
mutex_lock(&caching_ctl->mutex);
down_read(&fs_info->commit_root_sem);
load_block_group_size_class(caching_ctl, block_group);
if (btrfs_test_opt(fs_info, SPACE_CACHE)) {
ret = load_free_space_cache(block_group);
if (ret == 1) {
ret = 0;
goto done;
}
/*
* We failed to load the space cache, set ourselves to
* CACHE_STARTED and carry on.
*/
spin_lock(&block_group->lock);
block_group->cached = BTRFS_CACHE_STARTED;
spin_unlock(&block_group->lock);
wake_up(&caching_ctl->wait);
}
/*
* If we are in the transaction that populated the free space tree we
* can't actually cache from the free space tree as our commit root and
* real root are the same, so we could change the contents of the blocks
* while caching. Instead do the slow caching in this case, and after
* the transaction has committed we will be safe.
*/
if (btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE) &&
!(test_bit(BTRFS_FS_FREE_SPACE_TREE_UNTRUSTED, &fs_info->flags)))
ret = load_free_space_tree(caching_ctl);
else
ret = load_extent_tree_free(caching_ctl);
done:
spin_lock(&block_group->lock);
block_group->caching_ctl = NULL;
block_group->cached = ret ? BTRFS_CACHE_ERROR : BTRFS_CACHE_FINISHED;
spin_unlock(&block_group->lock);
#ifdef CONFIG_BTRFS_DEBUG
if (btrfs_should_fragment_free_space(block_group)) {
u64 bytes_used;
spin_lock(&block_group->space_info->lock);
spin_lock(&block_group->lock);
bytes_used = block_group->length - block_group->used;
block_group->space_info->bytes_used += bytes_used >> 1;
spin_unlock(&block_group->lock);
spin_unlock(&block_group->space_info->lock);
fragment_free_space(block_group);
}
#endif
up_read(&fs_info->commit_root_sem);
btrfs_free_excluded_extents(block_group);
mutex_unlock(&caching_ctl->mutex);
wake_up(&caching_ctl->wait);
btrfs_put_caching_control(caching_ctl);
btrfs_put_block_group(block_group);
}
int btrfs_cache_block_group(struct btrfs_block_group *cache, bool wait)
{
struct btrfs_fs_info *fs_info = cache->fs_info;
struct btrfs_caching_control *caching_ctl = NULL;
int ret = 0;
/* Allocator for zoned filesystems does not use the cache at all */
if (btrfs_is_zoned(fs_info))
return 0;
caching_ctl = kzalloc(sizeof(*caching_ctl), GFP_NOFS);
if (!caching_ctl)
return -ENOMEM;
INIT_LIST_HEAD(&caching_ctl->list);
mutex_init(&caching_ctl->mutex);
init_waitqueue_head(&caching_ctl->wait);
caching_ctl->block_group = cache;
refcount_set(&caching_ctl->count, 2);
atomic_set(&caching_ctl->progress, 0);
btrfs_init_work(&caching_ctl->work, caching_thread, NULL);
spin_lock(&cache->lock);
if (cache->cached != BTRFS_CACHE_NO) {
kfree(caching_ctl);
caching_ctl = cache->caching_ctl;
if (caching_ctl)
refcount_inc(&caching_ctl->count);
spin_unlock(&cache->lock);
goto out;
}
WARN_ON(cache->caching_ctl);
cache->caching_ctl = caching_ctl;
cache->cached = BTRFS_CACHE_STARTED;
spin_unlock(&cache->lock);
write_lock(&fs_info->block_group_cache_lock);
refcount_inc(&caching_ctl->count);
list_add_tail(&caching_ctl->list, &fs_info->caching_block_groups);
write_unlock(&fs_info->block_group_cache_lock);
btrfs_get_block_group(cache);
btrfs_queue_work(fs_info->caching_workers, &caching_ctl->work);
out:
if (wait && caching_ctl)
ret = btrfs_caching_ctl_wait_done(cache, caching_ctl);
if (caching_ctl)
btrfs_put_caching_control(caching_ctl);
return ret;
}
static void clear_avail_alloc_bits(struct btrfs_fs_info *fs_info, u64 flags)
{
u64 extra_flags = chunk_to_extended(flags) &
BTRFS_EXTENDED_PROFILE_MASK;
write_seqlock(&fs_info->profiles_lock);
if (flags & BTRFS_BLOCK_GROUP_DATA)
fs_info->avail_data_alloc_bits &= ~extra_flags;
if (flags & BTRFS_BLOCK_GROUP_METADATA)
fs_info->avail_metadata_alloc_bits &= ~extra_flags;
if (flags & BTRFS_BLOCK_GROUP_SYSTEM)
fs_info->avail_system_alloc_bits &= ~extra_flags;
write_sequnlock(&fs_info->profiles_lock);
}
/*
* Clear incompat bits for the following feature(s):
*
* - RAID56 - in case there's neither RAID5 nor RAID6 profile block group
* in the whole filesystem
*
* - RAID1C34 - same as above for RAID1C3 and RAID1C4 block groups
*/
static void clear_incompat_bg_bits(struct btrfs_fs_info *fs_info, u64 flags)
{
bool found_raid56 = false;
bool found_raid1c34 = false;
if ((flags & BTRFS_BLOCK_GROUP_RAID56_MASK) ||
(flags & BTRFS_BLOCK_GROUP_RAID1C3) ||
(flags & BTRFS_BLOCK_GROUP_RAID1C4)) {
struct list_head *head = &fs_info->space_info;
struct btrfs_space_info *sinfo;
list_for_each_entry_rcu(sinfo, head, list) {
down_read(&sinfo->groups_sem);
if (!list_empty(&sinfo->block_groups[BTRFS_RAID_RAID5]))
found_raid56 = true;
if (!list_empty(&sinfo->block_groups[BTRFS_RAID_RAID6]))
found_raid56 = true;
if (!list_empty(&sinfo->block_groups[BTRFS_RAID_RAID1C3]))
found_raid1c34 = true;
if (!list_empty(&sinfo->block_groups[BTRFS_RAID_RAID1C4]))
found_raid1c34 = true;
up_read(&sinfo->groups_sem);
}
if (!found_raid56)
btrfs_clear_fs_incompat(fs_info, RAID56);
if (!found_raid1c34)
btrfs_clear_fs_incompat(fs_info, RAID1C34);
}
}
static int remove_block_group_item(struct btrfs_trans_handle *trans,
struct btrfs_path *path,
struct btrfs_block_group *block_group)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_root *root;
struct btrfs_key key;
int ret;
root = btrfs_block_group_root(fs_info);
key.objectid = block_group->start;
key.type = BTRFS_BLOCK_GROUP_ITEM_KEY;
key.offset = block_group->length;
ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
if (ret > 0)
ret = -ENOENT;
if (ret < 0)
return ret;
ret = btrfs_del_item(trans, root, path);
return ret;
}
int btrfs_remove_block_group(struct btrfs_trans_handle *trans,
struct btrfs_chunk_map *map)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_path *path;
struct btrfs_block_group *block_group;
struct btrfs_free_cluster *cluster;
struct inode *inode;
struct kobject *kobj = NULL;
int ret;
int index;
int factor;
struct btrfs_caching_control *caching_ctl = NULL;
bool remove_map;
bool remove_rsv = false;
block_group = btrfs_lookup_block_group(fs_info, map->start);
BUG_ON(!block_group);
BUG_ON(!block_group->ro);
trace_btrfs_remove_block_group(block_group);
/*
* Free the reserved super bytes from this block group before
* remove it.
*/
btrfs_free_excluded_extents(block_group);
btrfs_free_ref_tree_range(fs_info, block_group->start,
block_group->length);
index = btrfs_bg_flags_to_raid_index(block_group->flags);
factor = btrfs_bg_type_to_factor(block_group->flags);
/* make sure this block group isn't part of an allocation cluster */
cluster = &fs_info->data_alloc_cluster;
spin_lock(&cluster->refill_lock);
btrfs_return_cluster_to_free_space(block_group, cluster);
spin_unlock(&cluster->refill_lock);
/*
* make sure this block group isn't part of a metadata
* allocation cluster
*/
cluster = &fs_info->meta_alloc_cluster;
spin_lock(&cluster->refill_lock);
btrfs_return_cluster_to_free_space(block_group, cluster);
spin_unlock(&cluster->refill_lock);
btrfs_clear_treelog_bg(block_group);
btrfs_clear_data_reloc_bg(block_group);
path = btrfs_alloc_path();
if (!path) {
ret = -ENOMEM;
goto out;
}
/*
* get the inode first so any iput calls done for the io_list
* aren't the final iput (no unlinks allowed now)
*/
inode = lookup_free_space_inode(block_group, path);
mutex_lock(&trans->transaction->cache_write_mutex);
/*
* Make sure our free space cache IO is done before removing the
* free space inode
*/
spin_lock(&trans->transaction->dirty_bgs_lock);
if (!list_empty(&block_group->io_list)) {
list_del_init(&block_group->io_list);
WARN_ON(!IS_ERR(inode) && inode != block_group->io_ctl.inode);
spin_unlock(&trans->transaction->dirty_bgs_lock);
btrfs_wait_cache_io(trans, block_group, path);
btrfs_put_block_group(block_group);
spin_lock(&trans->transaction->dirty_bgs_lock);
}
if (!list_empty(&block_group->dirty_list)) {
list_del_init(&block_group->dirty_list);
remove_rsv = true;
btrfs_put_block_group(block_group);
}
spin_unlock(&trans->transaction->dirty_bgs_lock);
mutex_unlock(&trans->transaction->cache_write_mutex);
ret = btrfs_remove_free_space_inode(trans, inode, block_group);
if (ret)
goto out;
write_lock(&fs_info->block_group_cache_lock);
rb_erase_cached(&block_group->cache_node,
&fs_info->block_group_cache_tree);
RB_CLEAR_NODE(&block_group->cache_node);
/* Once for the block groups rbtree */
btrfs_put_block_group(block_group);
write_unlock(&fs_info->block_group_cache_lock);
down_write(&block_group->space_info->groups_sem);
/*
* we must use list_del_init so people can check to see if they
* are still on the list after taking the semaphore
*/
list_del_init(&block_group->list);
if (list_empty(&block_group->space_info->block_groups[index])) {
kobj = block_group->space_info->block_group_kobjs[index];
block_group->space_info->block_group_kobjs[index] = NULL;
clear_avail_alloc_bits(fs_info, block_group->flags);
}
up_write(&block_group->space_info->groups_sem);
clear_incompat_bg_bits(fs_info, block_group->flags);
if (kobj) {
kobject_del(kobj);
kobject_put(kobj);
}
if (block_group->cached == BTRFS_CACHE_STARTED)
btrfs_wait_block_group_cache_done(block_group);
write_lock(&fs_info->block_group_cache_lock);
caching_ctl = btrfs_get_caching_control(block_group);
if (!caching_ctl) {
struct btrfs_caching_control *ctl;
list_for_each_entry(ctl, &fs_info->caching_block_groups, list) {
if (ctl->block_group == block_group) {
caching_ctl = ctl;
refcount_inc(&caching_ctl->count);
break;
}
}
}
if (caching_ctl)
list_del_init(&caching_ctl->list);
write_unlock(&fs_info->block_group_cache_lock);
if (caching_ctl) {
/* Once for the caching bgs list and once for us. */
btrfs_put_caching_control(caching_ctl);
btrfs_put_caching_control(caching_ctl);
}
spin_lock(&trans->transaction->dirty_bgs_lock);
WARN_ON(!list_empty(&block_group->dirty_list));
WARN_ON(!list_empty(&block_group->io_list));
spin_unlock(&trans->transaction->dirty_bgs_lock);
btrfs_remove_free_space_cache(block_group);
spin_lock(&block_group->space_info->lock);
list_del_init(&block_group->ro_list);
if (btrfs_test_opt(fs_info, ENOSPC_DEBUG)) {
WARN_ON(block_group->space_info->total_bytes
< block_group->length);
WARN_ON(block_group->space_info->bytes_readonly
< block_group->length - block_group->zone_unusable);
WARN_ON(block_group->space_info->bytes_zone_unusable
< block_group->zone_unusable);
WARN_ON(block_group->space_info->disk_total
< block_group->length * factor);
}
block_group->space_info->total_bytes -= block_group->length;
block_group->space_info->bytes_readonly -=
(block_group->length - block_group->zone_unusable);
block_group->space_info->bytes_zone_unusable -=
block_group->zone_unusable;
block_group->space_info->disk_total -= block_group->length * factor;
spin_unlock(&block_group->space_info->lock);
/*
* Remove the free space for the block group from the free space tree
* and the block group's item from the extent tree before marking the
* block group as removed. This is to prevent races with tasks that
* freeze and unfreeze a block group, this task and another task
* allocating a new block group - the unfreeze task ends up removing
* the block group's extent map before the task calling this function
* deletes the block group item from the extent tree, allowing for
* another task to attempt to create another block group with the same
* item key (and failing with -EEXIST and a transaction abort).
*/
ret = remove_block_group_free_space(trans, block_group);
if (ret)
goto out;
ret = remove_block_group_item(trans, path, block_group);
if (ret < 0)
goto out;
spin_lock(&block_group->lock);
set_bit(BLOCK_GROUP_FLAG_REMOVED, &block_group->runtime_flags);
/*
* At this point trimming or scrub can't start on this block group,
* because we removed the block group from the rbtree
* fs_info->block_group_cache_tree so no one can't find it anymore and
* even if someone already got this block group before we removed it
* from the rbtree, they have already incremented block_group->frozen -
* if they didn't, for the trimming case they won't find any free space
* entries because we already removed them all when we called
* btrfs_remove_free_space_cache().
*
* And we must not remove the chunk map from the fs_info->mapping_tree
* to prevent the same logical address range and physical device space
* ranges from being reused for a new block group. This is needed to
* avoid races with trimming and scrub.
*
* An fs trim operation (btrfs_trim_fs() / btrfs_ioctl_fitrim()) is
* completely transactionless, so while it is trimming a range the
* currently running transaction might finish and a new one start,
* allowing for new block groups to be created that can reuse the same
* physical device locations unless we take this special care.
*
* There may also be an implicit trim operation if the file system
* is mounted with -odiscard. The same protections must remain
* in place until the extents have been discarded completely when
* the transaction commit has completed.
*/
remove_map = (atomic_read(&block_group->frozen) == 0);
spin_unlock(&block_group->lock);
if (remove_map)
btrfs_remove_chunk_map(fs_info, map);
out:
/* Once for the lookup reference */
btrfs_put_block_group(block_group);
if (remove_rsv)
btrfs_dec_delayed_refs_rsv_bg_updates(fs_info);
btrfs_free_path(path);
return ret;
}
struct btrfs_trans_handle *btrfs_start_trans_remove_block_group(
struct btrfs_fs_info *fs_info, const u64 chunk_offset)
{
struct btrfs_root *root = btrfs_block_group_root(fs_info);
struct btrfs_chunk_map *map;
unsigned int num_items;
map = btrfs_find_chunk_map(fs_info, chunk_offset, 1);
ASSERT(map != NULL);
ASSERT(map->start == chunk_offset);
/*
* We need to reserve 3 + N units from the metadata space info in order
* to remove a block group (done at btrfs_remove_chunk() and at
* btrfs_remove_block_group()), which are used for:
*
* 1 unit for adding the free space inode's orphan (located in the tree
* of tree roots).
* 1 unit for deleting the block group item (located in the extent
* tree).
* 1 unit for deleting the free space item (located in tree of tree
* roots).
* N units for deleting N device extent items corresponding to each
* stripe (located in the device tree).
*
* In order to remove a block group we also need to reserve units in the
* system space info in order to update the chunk tree (update one or
* more device items and remove one chunk item), but this is done at
* btrfs_remove_chunk() through a call to check_system_chunk().
*/
num_items = 3 + map->num_stripes;
btrfs_free_chunk_map(map);
return btrfs_start_transaction_fallback_global_rsv(root, num_items);
}
/*
* Mark block group @cache read-only, so later write won't happen to block
* group @cache.
*
* If @force is not set, this function will only mark the block group readonly
* if we have enough free space (1M) in other metadata/system block groups.
* If @force is not set, this function will mark the block group readonly
* without checking free space.
*
* NOTE: This function doesn't care if other block groups can contain all the
* data in this block group. That check should be done by relocation routine,
* not this function.
*/
static int inc_block_group_ro(struct btrfs_block_group *cache, int force)
{
struct btrfs_space_info *sinfo = cache->space_info;
u64 num_bytes;
int ret = -ENOSPC;
spin_lock(&sinfo->lock);
spin_lock(&cache->lock);
if (cache->swap_extents) {
ret = -ETXTBSY;
goto out;
}
if (cache->ro) {
cache->ro++;
ret = 0;
goto out;
}
num_bytes = cache->length - cache->reserved - cache->pinned -
cache->bytes_super - cache->zone_unusable - cache->used;
/*
* Data never overcommits, even in mixed mode, so do just the straight
* check of left over space in how much we have allocated.
*/
if (force) {
ret = 0;
} else if (sinfo->flags & BTRFS_BLOCK_GROUP_DATA) {
u64 sinfo_used = btrfs_space_info_used(sinfo, true);
/*
* Here we make sure if we mark this bg RO, we still have enough
* free space as buffer.
*/
if (sinfo_used + num_bytes <= sinfo->total_bytes)
ret = 0;
} else {
/*
* We overcommit metadata, so we need to do the
* btrfs_can_overcommit check here, and we need to pass in
* BTRFS_RESERVE_NO_FLUSH to give ourselves the most amount of
* leeway to allow us to mark this block group as read only.
*/
if (btrfs_can_overcommit(cache->fs_info, sinfo, num_bytes,
BTRFS_RESERVE_NO_FLUSH))
ret = 0;
}
if (!ret) {
sinfo->bytes_readonly += num_bytes;
if (btrfs_is_zoned(cache->fs_info)) {
/* Migrate zone_unusable bytes to readonly */
sinfo->bytes_readonly += cache->zone_unusable;
sinfo->bytes_zone_unusable -= cache->zone_unusable;
cache->zone_unusable = 0;
}
cache->ro++;
list_add_tail(&cache->ro_list, &sinfo->ro_bgs);
}
out:
spin_unlock(&cache->lock);
spin_unlock(&sinfo->lock);
if (ret == -ENOSPC && btrfs_test_opt(cache->fs_info, ENOSPC_DEBUG)) {
btrfs_info(cache->fs_info,
"unable to make block group %llu ro", cache->start);
btrfs_dump_space_info(cache->fs_info, cache->space_info, 0, 0);
}
return ret;
}
static bool clean_pinned_extents(struct btrfs_trans_handle *trans,
struct btrfs_block_group *bg)
{
struct btrfs_fs_info *fs_info = bg->fs_info;
struct btrfs_transaction *prev_trans = NULL;
const u64 start = bg->start;
const u64 end = start + bg->length - 1;
int ret;
spin_lock(&fs_info->trans_lock);
if (trans->transaction->list.prev != &fs_info->trans_list) {
prev_trans = list_last_entry(&trans->transaction->list,
struct btrfs_transaction, list);
refcount_inc(&prev_trans->use_count);
}
spin_unlock(&fs_info->trans_lock);
/*
* Hold the unused_bg_unpin_mutex lock to avoid racing with
* btrfs_finish_extent_commit(). If we are at transaction N, another
* task might be running finish_extent_commit() for the previous
* transaction N - 1, and have seen a range belonging to the block
* group in pinned_extents before we were able to clear the whole block
* group range from pinned_extents. This means that task can lookup for
* the block group after we unpinned it from pinned_extents and removed
* it, leading to a BUG_ON() at unpin_extent_range().
*/
mutex_lock(&fs_info->unused_bg_unpin_mutex);
if (prev_trans) {
ret = clear_extent_bits(&prev_trans->pinned_extents, start, end,
EXTENT_DIRTY);
if (ret)
goto out;
}
ret = clear_extent_bits(&trans->transaction->pinned_extents, start, end,
EXTENT_DIRTY);
out:
mutex_unlock(&fs_info->unused_bg_unpin_mutex);
if (prev_trans)
btrfs_put_transaction(prev_trans);
return ret == 0;
}
/*
* Process the unused_bgs list and remove any that don't have any allocated
* space inside of them.
*/
void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
{
LIST_HEAD(retry_list);
struct btrfs_block_group *block_group;
struct btrfs_space_info *space_info;
struct btrfs_trans_handle *trans;
const bool async_trim_enabled = btrfs_test_opt(fs_info, DISCARD_ASYNC);
int ret = 0;
if (!test_bit(BTRFS_FS_OPEN, &fs_info->flags))
return;
if (btrfs_fs_closing(fs_info))
return;
/*
* Long running balances can keep us blocked here for eternity, so
* simply skip deletion if we're unable to get the mutex.
*/
if (!mutex_trylock(&fs_info->reclaim_bgs_lock))
return;
spin_lock(&fs_info->unused_bgs_lock);
while (!list_empty(&fs_info->unused_bgs)) {
u64 used;
int trimming;
block_group = list_first_entry(&fs_info->unused_bgs,
struct btrfs_block_group,
bg_list);
list_del_init(&block_group->bg_list);
space_info = block_group->space_info;
if (ret || btrfs_mixed_space_info(space_info)) {
btrfs_put_block_group(block_group);
continue;
}
spin_unlock(&fs_info->unused_bgs_lock);
btrfs_discard_cancel_work(&fs_info->discard_ctl, block_group);
/* Don't want to race with allocators so take the groups_sem */
down_write(&space_info->groups_sem);
/*
* Async discard moves the final block group discard to be prior
* to the unused_bgs code path. Therefore, if it's not fully
* trimmed, punt it back to the async discard lists.
*/
if (btrfs_test_opt(fs_info, DISCARD_ASYNC) &&
!btrfs_is_free_space_trimmed(block_group)) {
trace_btrfs_skip_unused_block_group(block_group);
up_write(&space_info->groups_sem);
/* Requeue if we failed because of async discard */
btrfs_discard_queue_work(&fs_info->discard_ctl,
block_group);
goto next;
}
spin_lock(&space_info->lock);
spin_lock(&block_group->lock);
if (btrfs_is_block_group_used(block_group) || block_group->ro ||
list_is_singular(&block_group->list)) {
/*
* We want to bail if we made new allocations or have
* outstanding allocations in this block group. We do
* the ro check in case balance is currently acting on
* this block group.
*/
trace_btrfs_skip_unused_block_group(block_group);
spin_unlock(&block_group->lock);
spin_unlock(&space_info->lock);
up_write(&space_info->groups_sem);
goto next;
}
/*
* The block group may be unused but there may be space reserved
* accounting with the existence of that block group, that is,
* space_info->bytes_may_use was incremented by a task but no
* space was yet allocated from the block group by the task.
* That space may or may not be allocated, as we are generally
* pessimistic about space reservation for metadata as well as
* for data when using compression (as we reserve space based on
* the worst case, when data can't be compressed, and before
* actually attempting compression, before starting writeback).
*
* So check if the total space of the space_info minus the size
* of this block group is less than the used space of the
* space_info - if that's the case, then it means we have tasks
* that might be relying on the block group in order to allocate
* extents, and add back the block group to the unused list when
* we finish, so that we retry later in case no tasks ended up
* needing to allocate extents from the block group.
*/
used = btrfs_space_info_used(space_info, true);
if (space_info->total_bytes - block_group->length < used) {
/*
* Add a reference for the list, compensate for the ref
* drop under the "next" label for the
* fs_info->unused_bgs list.
*/
btrfs_get_block_group(block_group);
list_add_tail(&block_group->bg_list, &retry_list);
trace_btrfs_skip_unused_block_group(block_group);
spin_unlock(&block_group->lock);
spin_unlock(&space_info->lock);
up_write(&space_info->groups_sem);
goto next;
}
spin_unlock(&block_group->lock);
spin_unlock(&space_info->lock);
/* We don't want to force the issue, only flip if it's ok. */
ret = inc_block_group_ro(block_group, 0);
up_write(&space_info->groups_sem);
if (ret < 0) {
ret = 0;
goto next;
}
ret = btrfs_zone_finish(block_group);
if (ret < 0) {
btrfs_dec_block_group_ro(block_group);
if (ret == -EAGAIN)
ret = 0;
goto next;
}
/*
* Want to do this before we do anything else so we can recover
* properly if we fail to join the transaction.
*/
trans = btrfs_start_trans_remove_block_group(fs_info,
block_group->start);
if (IS_ERR(trans)) {
btrfs_dec_block_group_ro(block_group);
ret = PTR_ERR(trans);
goto next;
}
/*
* We could have pending pinned extents for this block group,
* just delete them, we don't care about them anymore.
*/
if (!clean_pinned_extents(trans, block_group)) {
btrfs_dec_block_group_ro(block_group);
goto end_trans;
}
/*
* At this point, the block_group is read only and should fail
* new allocations. However, btrfs_finish_extent_commit() can
* cause this block_group to be placed back on the discard
* lists because now the block_group isn't fully discarded.
* Bail here and try again later after discarding everything.
*/
spin_lock(&fs_info->discard_ctl.lock);
if (!list_empty(&block_group->discard_list)) {
spin_unlock(&fs_info->discard_ctl.lock);
btrfs_dec_block_group_ro(block_group);
btrfs_discard_queue_work(&fs_info->discard_ctl,
block_group);
goto end_trans;
}
spin_unlock(&fs_info->discard_ctl.lock);
/* Reset pinned so btrfs_put_block_group doesn't complain */
spin_lock(&space_info->lock);
spin_lock(&block_group->lock);
btrfs_space_info_update_bytes_pinned(fs_info, space_info,
-block_group->pinned);
space_info->bytes_readonly += block_group->pinned;
block_group->pinned = 0;
spin_unlock(&block_group->lock);
spin_unlock(&space_info->lock);
/*
* The normal path here is an unused block group is passed here,
* then trimming is handled in the transaction commit path.
* Async discard interposes before this to do the trimming
* before coming down the unused block group path as trimming
* will no longer be done later in the transaction commit path.
*/
if (!async_trim_enabled && btrfs_test_opt(fs_info, DISCARD_ASYNC))
goto flip_async;
/*
* DISCARD can flip during remount. On zoned filesystems, we
* need to reset sequential-required zones.
*/
trimming = btrfs_test_opt(fs_info, DISCARD_SYNC) ||
btrfs_is_zoned(fs_info);
/* Implicit trim during transaction commit. */
if (trimming)
btrfs_freeze_block_group(block_group);
/*
* Btrfs_remove_chunk will abort the transaction if things go
* horribly wrong.
*/
ret = btrfs_remove_chunk(trans, block_group->start);
if (ret) {
if (trimming)
btrfs_unfreeze_block_group(block_group);
goto end_trans;
}
/*
* If we're not mounted with -odiscard, we can just forget
* about this block group. Otherwise we'll need to wait
* until transaction commit to do the actual discard.
*/
if (trimming) {
spin_lock(&fs_info->unused_bgs_lock);
/*
* A concurrent scrub might have added us to the list
* fs_info->unused_bgs, so use a list_move operation
* to add the block group to the deleted_bgs list.
*/
list_move(&block_group->bg_list,
&trans->transaction->deleted_bgs);
spin_unlock(&fs_info->unused_bgs_lock);
btrfs_get_block_group(block_group);
}
end_trans:
btrfs_end_transaction(trans);
next:
btrfs_put_block_group(block_group);
spin_lock(&fs_info->unused_bgs_lock);
}
list_splice_tail(&retry_list, &fs_info->unused_bgs);
spin_unlock(&fs_info->unused_bgs_lock);
mutex_unlock(&fs_info->reclaim_bgs_lock);
return;
flip_async:
btrfs_end_transaction(trans);
spin_lock(&fs_info->unused_bgs_lock);
list_splice_tail(&retry_list, &fs_info->unused_bgs);
spin_unlock(&fs_info->unused_bgs_lock);
mutex_unlock(&fs_info->reclaim_bgs_lock);
btrfs_put_block_group(block_group);
btrfs_discard_punt_unused_bgs_list(fs_info);
}
void btrfs_mark_bg_unused(struct btrfs_block_group *bg)
{
struct btrfs_fs_info *fs_info = bg->fs_info;
spin_lock(&fs_info->unused_bgs_lock);
if (list_empty(&bg->bg_list)) {
btrfs_get_block_group(bg);
trace_btrfs_add_unused_block_group(bg);
list_add_tail(&bg->bg_list, &fs_info->unused_bgs);
} else if (!test_bit(BLOCK_GROUP_FLAG_NEW, &bg->runtime_flags)) {
/* Pull out the block group from the reclaim_bgs list. */
trace_btrfs_add_unused_block_group(bg);
list_move_tail(&bg->bg_list, &fs_info->unused_bgs);
}
spin_unlock(&fs_info->unused_bgs_lock);
}
/*
* We want block groups with a low number of used bytes to be in the beginning
* of the list, so they will get reclaimed first.
*/
static int reclaim_bgs_cmp(void *unused, const struct list_head *a,
const struct list_head *b)
{
const struct btrfs_block_group *bg1, *bg2;
bg1 = list_entry(a, struct btrfs_block_group, bg_list);
bg2 = list_entry(b, struct btrfs_block_group, bg_list);
return bg1->used > bg2->used;
}
static inline bool btrfs_should_reclaim(struct btrfs_fs_info *fs_info)
{
if (btrfs_is_zoned(fs_info))
return btrfs_zoned_should_reclaim(fs_info);
return true;
}
static bool should_reclaim_block_group(struct btrfs_block_group *bg, u64 bytes_freed)
{
const struct btrfs_space_info *space_info = bg->space_info;
const int reclaim_thresh = READ_ONCE(space_info->bg_reclaim_threshold);
const u64 new_val = bg->used;
const u64 old_val = new_val + bytes_freed;
u64 thresh;
if (reclaim_thresh == 0)
return false;
thresh = mult_perc(bg->length, reclaim_thresh);
/*
* If we were below the threshold before don't reclaim, we are likely a
* brand new block group and we don't want to relocate new block groups.
*/
if (old_val < thresh)
return false;
if (new_val >= thresh)
return false;
return true;
}
void btrfs_reclaim_bgs_work(struct work_struct *work)
{
struct btrfs_fs_info *fs_info =
container_of(work, struct btrfs_fs_info, reclaim_bgs_work);
struct btrfs_block_group *bg;
struct btrfs_space_info *space_info;
if (!test_bit(BTRFS_FS_OPEN, &fs_info->flags))
return;
if (btrfs_fs_closing(fs_info))
return;
if (!btrfs_should_reclaim(fs_info))
return;
sb_start_write(fs_info->sb);
if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_BALANCE)) {
sb_end_write(fs_info->sb);
return;
}
/*
* Long running balances can keep us blocked here for eternity, so
* simply skip reclaim if we're unable to get the mutex.
*/
if (!mutex_trylock(&fs_info->reclaim_bgs_lock)) {
btrfs_exclop_finish(fs_info);
sb_end_write(fs_info->sb);
return;
}
spin_lock(&fs_info->unused_bgs_lock);
/*
* Sort happens under lock because we can't simply splice it and sort.
* The block groups might still be in use and reachable via bg_list,
* and their presence in the reclaim_bgs list must be preserved.
*/
list_sort(NULL, &fs_info->reclaim_bgs, reclaim_bgs_cmp);
while (!list_empty(&fs_info->reclaim_bgs)) {
u64 zone_unusable;
int ret = 0;
bg = list_first_entry(&fs_info->reclaim_bgs,
struct btrfs_block_group,
bg_list);
list_del_init(&bg->bg_list);
space_info = bg->space_info;
spin_unlock(&fs_info->unused_bgs_lock);
/* Don't race with allocators so take the groups_sem */
down_write(&space_info->groups_sem);
spin_lock(&bg->lock);
if (bg->reserved || bg->pinned || bg->ro) {
/*
* We want to bail if we made new allocations or have
* outstanding allocations in this block group. We do
* the ro check in case balance is currently acting on
* this block group.
*/
spin_unlock(&bg->lock);
up_write(&space_info->groups_sem);
goto next;
}
if (bg->used == 0) {
/*
* It is possible that we trigger relocation on a block
* group as its extents are deleted and it first goes
* below the threshold, then shortly after goes empty.
*
* In this case, relocating it does delete it, but has
* some overhead in relocation specific metadata, looking
* for the non-existent extents and running some extra
* transactions, which we can avoid by using one of the
* other mechanisms for dealing with empty block groups.
*/
if (!btrfs_test_opt(fs_info, DISCARD_ASYNC))
btrfs_mark_bg_unused(bg);
spin_unlock(&bg->lock);
up_write(&space_info->groups_sem);
goto next;
}
/*
* The block group might no longer meet the reclaim condition by
* the time we get around to reclaiming it, so to avoid
* reclaiming overly full block_groups, skip reclaiming them.
*
* Since the decision making process also depends on the amount
* being freed, pass in a fake giant value to skip that extra
* check, which is more meaningful when adding to the list in
* the first place.
*/
if (!should_reclaim_block_group(bg, bg->length)) {
spin_unlock(&bg->lock);
up_write(&space_info->groups_sem);
goto next;
}
spin_unlock(&bg->lock);
/*
* Get out fast, in case we're read-only or unmounting the
* filesystem. It is OK to drop block groups from the list even
* for the read-only case. As we did sb_start_write(),
* "mount -o remount,ro" won't happen and read-only filesystem
* means it is forced read-only due to a fatal error. So, it
* never gets back to read-write to let us reclaim again.
*/
if (btrfs_need_cleaner_sleep(fs_info)) {
up_write(&space_info->groups_sem);
goto next;
}
/*
* Cache the zone_unusable value before turning the block group
* to read only. As soon as the blog group is read only it's
* zone_unusable value gets moved to the block group's read-only
* bytes and isn't available for calculations anymore.
*/
zone_unusable = bg->zone_unusable;
ret = inc_block_group_ro(bg, 0);
up_write(&space_info->groups_sem);
if (ret < 0)
goto next;
btrfs_info(fs_info,
"reclaiming chunk %llu with %llu%% used %llu%% unusable",
bg->start,
div64_u64(bg->used * 100, bg->length),
div64_u64(zone_unusable * 100, bg->length));
trace_btrfs_reclaim_block_group(bg);
ret = btrfs_relocate_chunk(fs_info, bg->start);
if (ret) {
btrfs_dec_block_group_ro(bg);
btrfs_err(fs_info, "error relocating chunk %llu",
bg->start);
}
next:
if (ret)
btrfs_mark_bg_to_reclaim(bg);
btrfs_put_block_group(bg);
mutex_unlock(&fs_info->reclaim_bgs_lock);
/*
* Reclaiming all the block groups in the list can take really
* long. Prioritize cleaning up unused block groups.
*/
btrfs_delete_unused_bgs(fs_info);
/*
* If we are interrupted by a balance, we can just bail out. The
* cleaner thread restart again if necessary.
*/
if (!mutex_trylock(&fs_info->reclaim_bgs_lock))
goto end;
spin_lock(&fs_info->unused_bgs_lock);
}
spin_unlock(&fs_info->unused_bgs_lock);
mutex_unlock(&fs_info->reclaim_bgs_lock);
end:
btrfs_exclop_finish(fs_info);
sb_end_write(fs_info->sb);
}
void btrfs_reclaim_bgs(struct btrfs_fs_info *fs_info)
{
spin_lock(&fs_info->unused_bgs_lock);
if (!list_empty(&fs_info->reclaim_bgs))
queue_work(system_unbound_wq, &fs_info->reclaim_bgs_work);
spin_unlock(&fs_info->unused_bgs_lock);
}
void btrfs_mark_bg_to_reclaim(struct btrfs_block_group *bg)
{
struct btrfs_fs_info *fs_info = bg->fs_info;
spin_lock(&fs_info->unused_bgs_lock);
if (list_empty(&bg->bg_list)) {
btrfs_get_block_group(bg);
trace_btrfs_add_reclaim_block_group(bg);
list_add_tail(&bg->bg_list, &fs_info->reclaim_bgs);
}
spin_unlock(&fs_info->unused_bgs_lock);
}
static int read_bg_from_eb(struct btrfs_fs_info *fs_info, struct btrfs_key *key,
struct btrfs_path *path)
{
struct btrfs_chunk_map *map;
struct btrfs_block_group_item bg;
struct extent_buffer *leaf;
int slot;
u64 flags;
int ret = 0;
slot = path->slots[0];
leaf = path->nodes[0];
map = btrfs_find_chunk_map(fs_info, key->objectid, key->offset);
if (!map) {
btrfs_err(fs_info,
"logical %llu len %llu found bg but no related chunk",
key->objectid, key->offset);
return -ENOENT;
}
if (map->start != key->objectid || map->chunk_len != key->offset) {
btrfs_err(fs_info,
"block group %llu len %llu mismatch with chunk %llu len %llu",
key->objectid, key->offset, map->start, map->chunk_len);
ret = -EUCLEAN;
goto out_free_map;
}
read_extent_buffer(leaf, &bg, btrfs_item_ptr_offset(leaf, slot),
sizeof(bg));
flags = btrfs_stack_block_group_flags(&bg) &
BTRFS_BLOCK_GROUP_TYPE_MASK;
if (flags != (map->type & BTRFS_BLOCK_GROUP_TYPE_MASK)) {
btrfs_err(fs_info,
"block group %llu len %llu type flags 0x%llx mismatch with chunk type flags 0x%llx",
key->objectid, key->offset, flags,
(BTRFS_BLOCK_GROUP_TYPE_MASK & map->type));
ret = -EUCLEAN;
}
out_free_map:
btrfs_free_chunk_map(map);
return ret;
}
static int find_first_block_group(struct btrfs_fs_info *fs_info,
struct btrfs_path *path,
struct btrfs_key *key)
{
struct btrfs_root *root = btrfs_block_group_root(fs_info);
int ret;
struct btrfs_key found_key;
btrfs_for_each_slot(root, key, &found_key, path, ret) {
if (found_key.objectid >= key->objectid &&
found_key.type == BTRFS_BLOCK_GROUP_ITEM_KEY) {
return read_bg_from_eb(fs_info, &found_key, path);
}
}
return ret;
}
static void set_avail_alloc_bits(struct btrfs_fs_info *fs_info, u64 flags)
{
u64 extra_flags = chunk_to_extended(flags) &
BTRFS_EXTENDED_PROFILE_MASK;
write_seqlock(&fs_info->profiles_lock);
if (flags & BTRFS_BLOCK_GROUP_DATA)
fs_info->avail_data_alloc_bits |= extra_flags;
if (flags & BTRFS_BLOCK_GROUP_METADATA)
fs_info->avail_metadata_alloc_bits |= extra_flags;
if (flags & BTRFS_BLOCK_GROUP_SYSTEM)
fs_info->avail_system_alloc_bits |= extra_flags;
write_sequnlock(&fs_info->profiles_lock);
}
/*
* Map a physical disk address to a list of logical addresses.
*
* @fs_info: the filesystem
* @chunk_start: logical address of block group
* @physical: physical address to map to logical addresses
* @logical: return array of logical addresses which map to @physical
* @naddrs: length of @logical
* @stripe_len: size of IO stripe for the given block group
*
* Maps a particular @physical disk address to a list of @logical addresses.
* Used primarily to exclude those portions of a block group that contain super
* block copies.
*/
int btrfs_rmap_block(struct btrfs_fs_info *fs_info, u64 chunk_start,
u64 physical, u64 **logical, int *naddrs, int *stripe_len)
{
struct btrfs_chunk_map *map;
u64 *buf;
u64 bytenr;
u64 data_stripe_length;
u64 io_stripe_size;
int i, nr = 0;
int ret = 0;
map = btrfs_get_chunk_map(fs_info, chunk_start, 1);
if (IS_ERR(map))
return -EIO;
data_stripe_length = map->stripe_size;
io_stripe_size = BTRFS_STRIPE_LEN;
chunk_start = map->start;
/* For RAID5/6 adjust to a full IO stripe length */
if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK)
io_stripe_size = btrfs_stripe_nr_to_offset(nr_data_stripes(map));
buf = kcalloc(map->num_stripes, sizeof(u64), GFP_NOFS);
if (!buf) {
ret = -ENOMEM;
goto out;
}
for (i = 0; i < map->num_stripes; i++) {
bool already_inserted = false;
u32 stripe_nr;
u32 offset;
int j;
if (!in_range(physical, map->stripes[i].physical,
data_stripe_length))
continue;
stripe_nr = (physical - map->stripes[i].physical) >>
BTRFS_STRIPE_LEN_SHIFT;
offset = (physical - map->stripes[i].physical) &
BTRFS_STRIPE_LEN_MASK;
if (map->type & (BTRFS_BLOCK_GROUP_RAID0 |
BTRFS_BLOCK_GROUP_RAID10))
stripe_nr = div_u64(stripe_nr * map->num_stripes + i,
map->sub_stripes);
/*
* The remaining case would be for RAID56, multiply by
* nr_data_stripes(). Alternatively, just use rmap_len below
* instead of map->stripe_len
*/
bytenr = chunk_start + stripe_nr * io_stripe_size + offset;
/* Ensure we don't add duplicate addresses */
for (j = 0; j < nr; j++) {
if (buf[j] == bytenr) {
already_inserted = true;
break;
}
}
if (!already_inserted)
buf[nr++] = bytenr;
}
*logical = buf;
*naddrs = nr;
*stripe_len = io_stripe_size;
out:
btrfs_free_chunk_map(map);
return ret;
}
static int exclude_super_stripes(struct btrfs_block_group *cache)
{
struct btrfs_fs_info *fs_info = cache->fs_info;
const bool zoned = btrfs_is_zoned(fs_info);
u64 bytenr;
u64 *logical;
int stripe_len;
int i, nr, ret;
if (cache->start < BTRFS_SUPER_INFO_OFFSET) {
stripe_len = BTRFS_SUPER_INFO_OFFSET - cache->start;
cache->bytes_super += stripe_len;
ret = set_extent_bit(&fs_info->excluded_extents, cache->start,
cache->start + stripe_len - 1,
EXTENT_UPTODATE, NULL);
if (ret)
return ret;
}
for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
bytenr = btrfs_sb_offset(i);
ret = btrfs_rmap_block(fs_info, cache->start,
bytenr, &logical, &nr, &stripe_len);
if (ret)
return ret;
/* Shouldn't have super stripes in sequential zones */
if (zoned && nr) {
kfree(logical);
btrfs_err(fs_info,
"zoned: block group %llu must not contain super block",
cache->start);
return -EUCLEAN;
}
while (nr--) {
u64 len = min_t(u64, stripe_len,
cache->start + cache->length - logical[nr]);
cache->bytes_super += len;
ret = set_extent_bit(&fs_info->excluded_extents, logical[nr],
logical[nr] + len - 1,
EXTENT_UPTODATE, NULL);
if (ret) {
kfree(logical);
return ret;
}
}
kfree(logical);
}
return 0;
}
static struct btrfs_block_group *btrfs_create_block_group_cache(
struct btrfs_fs_info *fs_info, u64 start)
{
struct btrfs_block_group *cache;
cache = kzalloc(sizeof(*cache), GFP_NOFS);
if (!cache)
return NULL;
cache->free_space_ctl = kzalloc(sizeof(*cache->free_space_ctl),
GFP_NOFS);
if (!cache->free_space_ctl) {
kfree(cache);
return NULL;
}
cache->start = start;
cache->fs_info = fs_info;
cache->full_stripe_len = btrfs_full_stripe_len(fs_info, start);
cache->discard_index = BTRFS_DISCARD_INDEX_UNUSED;
refcount_set(&cache->refs, 1);
spin_lock_init(&cache->lock);
init_rwsem(&cache->data_rwsem);
INIT_LIST_HEAD(&cache->list);
INIT_LIST_HEAD(&cache->cluster_list);
INIT_LIST_HEAD(&cache->bg_list);
INIT_LIST_HEAD(&cache->ro_list);
INIT_LIST_HEAD(&cache->discard_list);
INIT_LIST_HEAD(&cache->dirty_list);
INIT_LIST_HEAD(&cache->io_list);
INIT_LIST_HEAD(&cache->active_bg_list);
btrfs_init_free_space_ctl(cache, cache->free_space_ctl);
atomic_set(&cache->frozen, 0);
mutex_init(&cache->free_space_lock);
return cache;
}
/*
* Iterate all chunks and verify that each of them has the corresponding block
* group
*/
static int check_chunk_block_group_mappings(struct btrfs_fs_info *fs_info)
{
u64 start = 0;
int ret = 0;
while (1) {
struct btrfs_chunk_map *map;
struct btrfs_block_group *bg;
/*
* btrfs_find_chunk_map() will return the first chunk map
* intersecting the range, so setting @length to 1 is enough to
* get the first chunk.
*/
map = btrfs_find_chunk_map(fs_info, start, 1);
if (!map)
break;
bg = btrfs_lookup_block_group(fs_info, map->start);
if (!bg) {
btrfs_err(fs_info,
"chunk start=%llu len=%llu doesn't have corresponding block group",
map->start, map->chunk_len);
ret = -EUCLEAN;
btrfs_free_chunk_map(map);
break;
}
if (bg->start != map->start || bg->length != map->chunk_len ||
(bg->flags & BTRFS_BLOCK_GROUP_TYPE_MASK) !=
(map->type & BTRFS_BLOCK_GROUP_TYPE_MASK)) {
btrfs_err(fs_info,
"chunk start=%llu len=%llu flags=0x%llx doesn't match block group start=%llu len=%llu flags=0x%llx",
map->start, map->chunk_len,
map->type & BTRFS_BLOCK_GROUP_TYPE_MASK,
bg->start, bg->length,
bg->flags & BTRFS_BLOCK_GROUP_TYPE_MASK);
ret = -EUCLEAN;
btrfs_free_chunk_map(map);
btrfs_put_block_group(bg);
break;
}
start = map->start + map->chunk_len;
btrfs_free_chunk_map(map);
btrfs_put_block_group(bg);
}
return ret;
}
static int read_one_block_group(struct btrfs_fs_info *info,
struct btrfs_block_group_item *bgi,
const struct btrfs_key *key,
int need_clear)
{
struct btrfs_block_group *cache;
const bool mixed = btrfs_fs_incompat(info, MIXED_GROUPS);
int ret;
ASSERT(key->type == BTRFS_BLOCK_GROUP_ITEM_KEY);
cache = btrfs_create_block_group_cache(info, key->objectid);
if (!cache)
return -ENOMEM;
cache->length = key->offset;
cache->used = btrfs_stack_block_group_used(bgi);
cache->commit_used = cache->used;
cache->flags = btrfs_stack_block_group_flags(bgi);
cache->global_root_id = btrfs_stack_block_group_chunk_objectid(bgi);
set_free_space_tree_thresholds(cache);
if (need_clear) {
/*
* When we mount with old space cache, we need to
* set BTRFS_DC_CLEAR and set dirty flag.
*
* a) Setting 'BTRFS_DC_CLEAR' makes sure that we
* truncate the old free space cache inode and
* setup a new one.
* b) Setting 'dirty flag' makes sure that we flush
* the new space cache info onto disk.
*/
if (btrfs_test_opt(info, SPACE_CACHE))
cache->disk_cache_state = BTRFS_DC_CLEAR;
}
if (!mixed && ((cache->flags & BTRFS_BLOCK_GROUP_METADATA) &&
(cache->flags & BTRFS_BLOCK_GROUP_DATA))) {
btrfs_err(info,
"bg %llu is a mixed block group but filesystem hasn't enabled mixed block groups",
cache->start);
ret = -EINVAL;
goto error;
}
ret = btrfs_load_block_group_zone_info(cache, false);
if (ret) {
btrfs_err(info, "zoned: failed to load zone info of bg %llu",
cache->start);
goto error;
}
/*
* We need to exclude the super stripes now so that the space info has
* super bytes accounted for, otherwise we'll think we have more space
* than we actually do.
*/
ret = exclude_super_stripes(cache);
if (ret) {
/* We may have excluded something, so call this just in case. */
btrfs_free_excluded_extents(cache);
goto error;
}
/*
* For zoned filesystem, space after the allocation offset is the only
* free space for a block group. So, we don't need any caching work.
* btrfs_calc_zone_unusable() will set the amount of free space and
* zone_unusable space.
*
* For regular filesystem, check for two cases, either we are full, and
* therefore don't need to bother with the caching work since we won't
* find any space, or we are empty, and we can just add all the space
* in and be done with it. This saves us _a_lot_ of time, particularly
* in the full case.
*/
if (btrfs_is_zoned(info)) {
btrfs_calc_zone_unusable(cache);
/* Should not have any excluded extents. Just in case, though. */
btrfs_free_excluded_extents(cache);
} else if (cache->length == cache->used) {
cache->cached = BTRFS_CACHE_FINISHED;
btrfs_free_excluded_extents(cache);
} else if (cache->used == 0) {
cache->cached = BTRFS_CACHE_FINISHED;
ret = btrfs_add_new_free_space(cache, cache->start,
cache->start + cache->length, NULL);
btrfs_free_excluded_extents(cache);
if (ret)
goto error;
}
ret = btrfs_add_block_group_cache(info, cache);
if (ret) {
btrfs_remove_free_space_cache(cache);
goto error;
}
trace_btrfs_add_block_group(info, cache, 0);
btrfs_add_bg_to_space_info(info, cache);
set_avail_alloc_bits(info, cache->flags);
if (btrfs_chunk_writeable(info, cache->start)) {
if (cache->used == 0) {
ASSERT(list_empty(&cache->bg_list));
if (btrfs_test_opt(info, DISCARD_ASYNC))
btrfs_discard_queue_work(&info->discard_ctl, cache);
else
btrfs_mark_bg_unused(cache);
}
} else {
inc_block_group_ro(cache, 1);
}
return 0;
error:
btrfs_put_block_group(cache);
return ret;
}
static int fill_dummy_bgs(struct btrfs_fs_info *fs_info)
{
struct rb_node *node;
int ret = 0;
for (node = rb_first_cached(&fs_info->mapping_tree); node; node = rb_next(node)) {
struct btrfs_chunk_map *map;
struct btrfs_block_group *bg;
map = rb_entry(node, struct btrfs_chunk_map, rb_node);
bg = btrfs_create_block_group_cache(fs_info, map->start);
if (!bg) {
ret = -ENOMEM;
break;
}
/* Fill dummy cache as FULL */
bg->length = map->chunk_len;
bg->flags = map->type;
bg->cached = BTRFS_CACHE_FINISHED;
bg->used = map->chunk_len;
bg->flags = map->type;
ret = btrfs_add_block_group_cache(fs_info, bg);
/*
* We may have some valid block group cache added already, in
* that case we skip to the next one.
*/
if (ret == -EEXIST) {
ret = 0;
btrfs_put_block_group(bg);
continue;
}
if (ret) {
btrfs_remove_free_space_cache(bg);
btrfs_put_block_group(bg);
break;
}
btrfs_add_bg_to_space_info(fs_info, bg);
set_avail_alloc_bits(fs_info, bg->flags);
}
if (!ret)
btrfs_init_global_block_rsv(fs_info);
return ret;
}
int btrfs_read_block_groups(struct btrfs_fs_info *info)
{
struct btrfs_root *root = btrfs_block_group_root(info);
struct btrfs_path *path;
int ret;
struct btrfs_block_group *cache;
struct btrfs_space_info *space_info;
struct btrfs_key key;
int need_clear = 0;
u64 cache_gen;
/*
* Either no extent root (with ibadroots rescue option) or we have
* unsupported RO options. The fs can never be mounted read-write, so no
* need to waste time searching block group items.
*
* This also allows new extent tree related changes to be RO compat,
* no need for a full incompat flag.
*/
if (!root || (btrfs_super_compat_ro_flags(info->super_copy) &
~BTRFS_FEATURE_COMPAT_RO_SUPP))
return fill_dummy_bgs(info);
key.objectid = 0;
key.offset = 0;
key.type = BTRFS_BLOCK_GROUP_ITEM_KEY;
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
cache_gen = btrfs_super_cache_generation(info->super_copy);
if (btrfs_test_opt(info, SPACE_CACHE) &&
btrfs_super_generation(info->super_copy) != cache_gen)
need_clear = 1;
if (btrfs_test_opt(info, CLEAR_CACHE))
need_clear = 1;
while (1) {
struct btrfs_block_group_item bgi;
struct extent_buffer *leaf;
int slot;
ret = find_first_block_group(info, path, &key);
if (ret > 0)
break;
if (ret != 0)
goto error;
leaf = path->nodes[0];
slot = path->slots[0];
read_extent_buffer(leaf, &bgi, btrfs_item_ptr_offset(leaf, slot),
sizeof(bgi));
btrfs_item_key_to_cpu(leaf, &key, slot);
btrfs_release_path(path);
ret = read_one_block_group(info, &bgi, &key, need_clear);
if (ret < 0)
goto error;
key.objectid += key.offset;
key.offset = 0;
}
btrfs_release_path(path);
list_for_each_entry(space_info, &info->space_info, list) {
int i;
for (i = 0; i < BTRFS_NR_RAID_TYPES; i++) {
if (list_empty(&space_info->block_groups[i]))
continue;
cache = list_first_entry(&space_info->block_groups[i],
struct btrfs_block_group,
list);
btrfs_sysfs_add_block_group_type(cache);
}
if (!(btrfs_get_alloc_profile(info, space_info->flags) &
(BTRFS_BLOCK_GROUP_RAID10 |
BTRFS_BLOCK_GROUP_RAID1_MASK |
BTRFS_BLOCK_GROUP_RAID56_MASK |
BTRFS_BLOCK_GROUP_DUP)))
continue;
/*
* Avoid allocating from un-mirrored block group if there are
* mirrored block groups.
*/
list_for_each_entry(cache,
&space_info->block_groups[BTRFS_RAID_RAID0],
list)
inc_block_group_ro(cache, 1);
list_for_each_entry(cache,
&space_info->block_groups[BTRFS_RAID_SINGLE],
list)
inc_block_group_ro(cache, 1);
}
btrfs_init_global_block_rsv(info);
ret = check_chunk_block_group_mappings(info);
error:
btrfs_free_path(path);
/*
* We've hit some error while reading the extent tree, and have
* rescue=ibadroots mount option.
* Try to fill the tree using dummy block groups so that the user can
* continue to mount and grab their data.
*/
if (ret && btrfs_test_opt(info, IGNOREBADROOTS))
ret = fill_dummy_bgs(info);
return ret;
}
/*
* This function, insert_block_group_item(), belongs to the phase 2 of chunk
* allocation.
*
* See the comment at btrfs_chunk_alloc() for details about the chunk allocation
* phases.
*/
static int insert_block_group_item(struct btrfs_trans_handle *trans,
struct btrfs_block_group *block_group)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_block_group_item bgi;
struct btrfs_root *root = btrfs_block_group_root(fs_info);
struct btrfs_key key;
u64 old_commit_used;
int ret;
spin_lock(&block_group->lock);
btrfs_set_stack_block_group_used(&bgi, block_group->used);
btrfs_set_stack_block_group_chunk_objectid(&bgi,
block_group->global_root_id);
btrfs_set_stack_block_group_flags(&bgi, block_group->flags);
old_commit_used = block_group->commit_used;
block_group->commit_used = block_group->used;
key.objectid = block_group->start;
key.type = BTRFS_BLOCK_GROUP_ITEM_KEY;
key.offset = block_group->length;
spin_unlock(&block_group->lock);
ret = btrfs_insert_item(trans, root, &key, &bgi, sizeof(bgi));
if (ret < 0) {
spin_lock(&block_group->lock);
block_group->commit_used = old_commit_used;
spin_unlock(&block_group->lock);
}
return ret;
}
static int insert_dev_extent(struct btrfs_trans_handle *trans,
struct btrfs_device *device, u64 chunk_offset,
u64 start, u64 num_bytes)
{
struct btrfs_fs_info *fs_info = device->fs_info;
struct btrfs_root *root = fs_info->dev_root;
struct btrfs_path *path;
struct btrfs_dev_extent *extent;
struct extent_buffer *leaf;
struct btrfs_key key;
int ret;
WARN_ON(!test_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &device->dev_state));
WARN_ON(test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state));
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
key.objectid = device->devid;
key.type = BTRFS_DEV_EXTENT_KEY;
key.offset = start;
ret = btrfs_insert_empty_item(trans, root, path, &key, sizeof(*extent));
if (ret)
goto out;
leaf = path->nodes[0];
extent = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dev_extent);
btrfs_set_dev_extent_chunk_tree(leaf, extent, BTRFS_CHUNK_TREE_OBJECTID);
btrfs_set_dev_extent_chunk_objectid(leaf, extent,
BTRFS_FIRST_CHUNK_TREE_OBJECTID);
btrfs_set_dev_extent_chunk_offset(leaf, extent, chunk_offset);
btrfs_set_dev_extent_length(leaf, extent, num_bytes);
btrfs_mark_buffer_dirty(trans, leaf);
out:
btrfs_free_path(path);
return ret;
}
/*
* This function belongs to phase 2.
*
* See the comment at btrfs_chunk_alloc() for details about the chunk allocation
* phases.
*/
static int insert_dev_extents(struct btrfs_trans_handle *trans,
u64 chunk_offset, u64 chunk_size)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_device *device;
struct btrfs_chunk_map *map;
u64 dev_offset;
int i;
int ret = 0;
map = btrfs_get_chunk_map(fs_info, chunk_offset, chunk_size);
if (IS_ERR(map))
return PTR_ERR(map);
/*
* Take the device list mutex to prevent races with the final phase of
* a device replace operation that replaces the device object associated
* with the map's stripes, because the device object's id can change
* at any time during that final phase of the device replace operation
* (dev-replace.c:btrfs_dev_replace_finishing()), so we could grab the
* replaced device and then see it with an ID of BTRFS_DEV_REPLACE_DEVID,
* resulting in persisting a device extent item with such ID.
*/
mutex_lock(&fs_info->fs_devices->device_list_mutex);
for (i = 0; i < map->num_stripes; i++) {
device = map->stripes[i].dev;
dev_offset = map->stripes[i].physical;
ret = insert_dev_extent(trans, device, chunk_offset, dev_offset,
map->stripe_size);
if (ret)
break;
}
mutex_unlock(&fs_info->fs_devices->device_list_mutex);
btrfs_free_chunk_map(map);
return ret;
}
/*
* This function, btrfs_create_pending_block_groups(), belongs to the phase 2 of
* chunk allocation.
*
* See the comment at btrfs_chunk_alloc() for details about the chunk allocation
* phases.
*/
void btrfs_create_pending_block_groups(struct btrfs_trans_handle *trans)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_block_group *block_group;
int ret = 0;
while (!list_empty(&trans->new_bgs)) {
int index;
block_group = list_first_entry(&trans->new_bgs,
struct btrfs_block_group,
bg_list);
if (ret)
goto next;
index = btrfs_bg_flags_to_raid_index(block_group->flags);
ret = insert_block_group_item(trans, block_group);
if (ret)
btrfs_abort_transaction(trans, ret);
if (!test_bit(BLOCK_GROUP_FLAG_CHUNK_ITEM_INSERTED,
&block_group->runtime_flags)) {
mutex_lock(&fs_info->chunk_mutex);
ret = btrfs_chunk_alloc_add_chunk_item(trans, block_group);
mutex_unlock(&fs_info->chunk_mutex);
if (ret)
btrfs_abort_transaction(trans, ret);
}
ret = insert_dev_extents(trans, block_group->start,
block_group->length);
if (ret)
btrfs_abort_transaction(trans, ret);
add_block_group_free_space(trans, block_group);
/*
* If we restriped during balance, we may have added a new raid
* type, so now add the sysfs entries when it is safe to do so.
* We don't have to worry about locking here as it's handled in
* btrfs_sysfs_add_block_group_type.
*/
if (block_group->space_info->block_group_kobjs[index] == NULL)
btrfs_sysfs_add_block_group_type(block_group);
/* Already aborted the transaction if it failed. */
next:
btrfs_dec_delayed_refs_rsv_bg_inserts(fs_info);
list_del_init(&block_group->bg_list);
clear_bit(BLOCK_GROUP_FLAG_NEW, &block_group->runtime_flags);
/*
* If the block group is still unused, add it to the list of
* unused block groups. The block group may have been created in
* order to satisfy a space reservation, in which case the
* extent allocation only happens later. But often we don't
* actually need to allocate space that we previously reserved,
* so the block group may become unused for a long time. For
* example for metadata we generally reserve space for a worst
* possible scenario, but then don't end up allocating all that
* space or none at all (due to no need to COW, extent buffers
* were already COWed in the current transaction and still
* unwritten, tree heights lower than the maximum possible
* height, etc). For data we generally reserve the axact amount
* of space we are going to allocate later, the exception is
* when using compression, as we must reserve space based on the
* uncompressed data size, because the compression is only done
* when writeback triggered and we don't know how much space we
* are actually going to need, so we reserve the uncompressed
* size because the data may be uncompressible in the worst case.
*/
if (ret == 0) {
bool used;
spin_lock(&block_group->lock);
used = btrfs_is_block_group_used(block_group);
spin_unlock(&block_group->lock);
if (!used)
btrfs_mark_bg_unused(block_group);
}
}
btrfs_trans_release_chunk_metadata(trans);
}
/*
* For extent tree v2 we use the block_group_item->chunk_offset to point at our
* global root id. For v1 it's always set to BTRFS_FIRST_CHUNK_TREE_OBJECTID.
*/
static u64 calculate_global_root_id(struct btrfs_fs_info *fs_info, u64 offset)
{
u64 div = SZ_1G;
u64 index;
if (!btrfs_fs_incompat(fs_info, EXTENT_TREE_V2))
return BTRFS_FIRST_CHUNK_TREE_OBJECTID;
/* If we have a smaller fs index based on 128MiB. */
if (btrfs_super_total_bytes(fs_info->super_copy) <= (SZ_1G * 10ULL))
div = SZ_128M;
offset = div64_u64(offset, div);
div64_u64_rem(offset, fs_info->nr_global_roots, &index);
return index;
}
struct btrfs_block_group *btrfs_make_block_group(struct btrfs_trans_handle *trans,
u64 type,
u64 chunk_offset, u64 size)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_block_group *cache;
int ret;
btrfs_set_log_full_commit(trans);
cache = btrfs_create_block_group_cache(fs_info, chunk_offset);
if (!cache)
return ERR_PTR(-ENOMEM);
/*
* Mark it as new before adding it to the rbtree of block groups or any
* list, so that no other task finds it and calls btrfs_mark_bg_unused()
* before the new flag is set.
*/
set_bit(BLOCK_GROUP_FLAG_NEW, &cache->runtime_flags);
cache->length = size;
set_free_space_tree_thresholds(cache);
cache->flags = type;
cache->cached = BTRFS_CACHE_FINISHED;
cache->global_root_id = calculate_global_root_id(fs_info, cache->start);
if (btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE))
set_bit(BLOCK_GROUP_FLAG_NEEDS_FREE_SPACE, &cache->runtime_flags);
ret = btrfs_load_block_group_zone_info(cache, true);
if (ret) {
btrfs_put_block_group(cache);
return ERR_PTR(ret);
}
ret = exclude_super_stripes(cache);
if (ret) {
/* We may have excluded something, so call this just in case */
btrfs_free_excluded_extents(cache);
btrfs_put_block_group(cache);
return ERR_PTR(ret);
}
ret = btrfs_add_new_free_space(cache, chunk_offset, chunk_offset + size, NULL);
btrfs_free_excluded_extents(cache);
if (ret) {
btrfs_put_block_group(cache);
return ERR_PTR(ret);
}
/*
* Ensure the corresponding space_info object is created and
* assigned to our block group. We want our bg to be added to the rbtree
* with its ->space_info set.
*/
cache->space_info = btrfs_find_space_info(fs_info, cache->flags);
ASSERT(cache->space_info);
ret = btrfs_add_block_group_cache(fs_info, cache);
if (ret) {
btrfs_remove_free_space_cache(cache);
btrfs_put_block_group(cache);
return ERR_PTR(ret);
}
/*
* Now that our block group has its ->space_info set and is inserted in
* the rbtree, update the space info's counters.
*/
trace_btrfs_add_block_group(fs_info, cache, 1);
btrfs_add_bg_to_space_info(fs_info, cache);
btrfs_update_global_block_rsv(fs_info);
#ifdef CONFIG_BTRFS_DEBUG
if (btrfs_should_fragment_free_space(cache)) {
cache->space_info->bytes_used += size >> 1;
fragment_free_space(cache);
}
#endif
list_add_tail(&cache->bg_list, &trans->new_bgs);
btrfs_inc_delayed_refs_rsv_bg_inserts(fs_info);
set_avail_alloc_bits(fs_info, type);
return cache;
}
/*
* Mark one block group RO, can be called several times for the same block
* group.
*
* @cache: the destination block group
* @do_chunk_alloc: whether need to do chunk pre-allocation, this is to
* ensure we still have some free space after marking this
* block group RO.
*/
int btrfs_inc_block_group_ro(struct btrfs_block_group *cache,
bool do_chunk_alloc)
{
struct btrfs_fs_info *fs_info = cache->fs_info;
struct btrfs_trans_handle *trans;
struct btrfs_root *root = btrfs_block_group_root(fs_info);
u64 alloc_flags;
int ret;
bool dirty_bg_running;
/*
* This can only happen when we are doing read-only scrub on read-only
* mount.
* In that case we should not start a new transaction on read-only fs.
* Thus here we skip all chunk allocations.
*/
if (sb_rdonly(fs_info->sb)) {
mutex_lock(&fs_info->ro_block_group_mutex);
ret = inc_block_group_ro(cache, 0);
mutex_unlock(&fs_info->ro_block_group_mutex);
return ret;
}
do {
trans = btrfs_join_transaction(root);
if (IS_ERR(trans))
return PTR_ERR(trans);
dirty_bg_running = false;
/*
* We're not allowed to set block groups readonly after the dirty
* block group cache has started writing. If it already started,
* back off and let this transaction commit.
*/
mutex_lock(&fs_info->ro_block_group_mutex);
if (test_bit(BTRFS_TRANS_DIRTY_BG_RUN, &trans->transaction->flags)) {
u64 transid = trans->transid;
mutex_unlock(&fs_info->ro_block_group_mutex);
btrfs_end_transaction(trans);
ret = btrfs_wait_for_commit(fs_info, transid);
if (ret)
return ret;
dirty_bg_running = true;
}
} while (dirty_bg_running);
if (do_chunk_alloc) {
/*
* If we are changing raid levels, try to allocate a
* corresponding block group with the new raid level.
*/
alloc_flags = btrfs_get_alloc_profile(fs_info, cache->flags);
if (alloc_flags != cache->flags) {
ret = btrfs_chunk_alloc(trans, alloc_flags,
CHUNK_ALLOC_FORCE);
/*
* ENOSPC is allowed here, we may have enough space
* already allocated at the new raid level to carry on
*/
if (ret == -ENOSPC)
ret = 0;
if (ret < 0)
goto out;
}
}
ret = inc_block_group_ro(cache, 0);
if (!ret)
goto out;
if (ret == -ETXTBSY)
goto unlock_out;
/*
* Skip chunk allocation if the bg is SYSTEM, this is to avoid system
* chunk allocation storm to exhaust the system chunk array. Otherwise
* we still want to try our best to mark the block group read-only.
*/
if (!do_chunk_alloc && ret == -ENOSPC &&
(cache->flags & BTRFS_BLOCK_GROUP_SYSTEM))
goto unlock_out;
alloc_flags = btrfs_get_alloc_profile(fs_info, cache->space_info->flags);
ret = btrfs_chunk_alloc(trans, alloc_flags, CHUNK_ALLOC_FORCE);
if (ret < 0)
goto out;
/*
* We have allocated a new chunk. We also need to activate that chunk to
* grant metadata tickets for zoned filesystem.
*/
ret = btrfs_zoned_activate_one_bg(fs_info, cache->space_info, true);
if (ret < 0)
goto out;
ret = inc_block_group_ro(cache, 0);
if (ret == -ETXTBSY)
goto unlock_out;
out:
if (cache->flags & BTRFS_BLOCK_GROUP_SYSTEM) {
alloc_flags = btrfs_get_alloc_profile(fs_info, cache->flags);
mutex_lock(&fs_info->chunk_mutex);
check_system_chunk(trans, alloc_flags);
mutex_unlock(&fs_info->chunk_mutex);
}
unlock_out:
mutex_unlock(&fs_info->ro_block_group_mutex);
btrfs_end_transaction(trans);
return ret;
}
void btrfs_dec_block_group_ro(struct btrfs_block_group *cache)
{
struct btrfs_space_info *sinfo = cache->space_info;
u64 num_bytes;
BUG_ON(!cache->ro);
spin_lock(&sinfo->lock);
spin_lock(&cache->lock);
if (!--cache->ro) {
if (btrfs_is_zoned(cache->fs_info)) {
/* Migrate zone_unusable bytes back */
cache->zone_unusable =
(cache->alloc_offset - cache->used) +
(cache->length - cache->zone_capacity);
sinfo->bytes_zone_unusable += cache->zone_unusable;
sinfo->bytes_readonly -= cache->zone_unusable;
}
num_bytes = cache->length - cache->reserved -
cache->pinned - cache->bytes_super -
cache->zone_unusable - cache->used;
sinfo->bytes_readonly -= num_bytes;
list_del_init(&cache->ro_list);
}
spin_unlock(&cache->lock);
spin_unlock(&sinfo->lock);
}
static int update_block_group_item(struct btrfs_trans_handle *trans,
struct btrfs_path *path,
struct btrfs_block_group *cache)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
int ret;
struct btrfs_root *root = btrfs_block_group_root(fs_info);
unsigned long bi;
struct extent_buffer *leaf;
struct btrfs_block_group_item bgi;
struct btrfs_key key;
u64 old_commit_used;
u64 used;
/*
* Block group items update can be triggered out of commit transaction
* critical section, thus we need a consistent view of used bytes.
* We cannot use cache->used directly outside of the spin lock, as it
* may be changed.
*/
spin_lock(&cache->lock);
old_commit_used = cache->commit_used;
used = cache->used;
/* No change in used bytes, can safely skip it. */
if (cache->commit_used == used) {
spin_unlock(&cache->lock);
return 0;
}
cache->commit_used = used;
spin_unlock(&cache->lock);
key.objectid = cache->start;
key.type = BTRFS_BLOCK_GROUP_ITEM_KEY;
key.offset = cache->length;
ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
if (ret) {
if (ret > 0)
ret = -ENOENT;
goto fail;
}
leaf = path->nodes[0];
bi = btrfs_item_ptr_offset(leaf, path->slots[0]);
btrfs_set_stack_block_group_used(&bgi, used);
btrfs_set_stack_block_group_chunk_objectid(&bgi,
cache->global_root_id);
btrfs_set_stack_block_group_flags(&bgi, cache->flags);
write_extent_buffer(leaf, &bgi, bi, sizeof(bgi));
btrfs_mark_buffer_dirty(trans, leaf);
fail:
btrfs_release_path(path);
/*
* We didn't update the block group item, need to revert commit_used
* unless the block group item didn't exist yet - this is to prevent a
* race with a concurrent insertion of the block group item, with
* insert_block_group_item(), that happened just after we attempted to
* update. In that case we would reset commit_used to 0 just after the
* insertion set it to a value greater than 0 - if the block group later
* becomes with 0 used bytes, we would incorrectly skip its update.
*/
if (ret < 0 && ret != -ENOENT) {
spin_lock(&cache->lock);
cache->commit_used = old_commit_used;
spin_unlock(&cache->lock);
}
return ret;
}
static int cache_save_setup(struct btrfs_block_group *block_group,
struct btrfs_trans_handle *trans,
struct btrfs_path *path)
{
struct btrfs_fs_info *fs_info = block_group->fs_info;
struct inode *inode = NULL;
struct extent_changeset *data_reserved = NULL;
u64 alloc_hint = 0;
int dcs = BTRFS_DC_ERROR;
u64 cache_size = 0;
int retries = 0;
int ret = 0;
if (!btrfs_test_opt(fs_info, SPACE_CACHE))
return 0;
/*
* If this block group is smaller than 100 megs don't bother caching the
* block group.
*/
if (block_group->length < (100 * SZ_1M)) {
spin_lock(&block_group->lock);
block_group->disk_cache_state = BTRFS_DC_WRITTEN;
spin_unlock(&block_group->lock);
return 0;
}
if (TRANS_ABORTED(trans))
return 0;
again:
inode = lookup_free_space_inode(block_group, path);
if (IS_ERR(inode) && PTR_ERR(inode) != -ENOENT) {
ret = PTR_ERR(inode);
btrfs_release_path(path);
goto out;
}
if (IS_ERR(inode)) {
BUG_ON(retries);
retries++;
if (block_group->ro)
goto out_free;
ret = create_free_space_inode(trans, block_group, path);
if (ret)
goto out_free;
goto again;
}
/*
* We want to set the generation to 0, that way if anything goes wrong
* from here on out we know not to trust this cache when we load up next
* time.
*/
BTRFS_I(inode)->generation = 0;
ret = btrfs_update_inode(trans, BTRFS_I(inode));
if (ret) {
/*
* So theoretically we could recover from this, simply set the
* super cache generation to 0 so we know to invalidate the
* cache, but then we'd have to keep track of the block groups
* that fail this way so we know we _have_ to reset this cache
* before the next commit or risk reading stale cache. So to
* limit our exposure to horrible edge cases lets just abort the
* transaction, this only happens in really bad situations
* anyway.
*/
btrfs_abort_transaction(trans, ret);
goto out_put;
}
WARN_ON(ret);
/* We've already setup this transaction, go ahead and exit */
if (block_group->cache_generation == trans->transid &&
i_size_read(inode)) {
dcs = BTRFS_DC_SETUP;
goto out_put;
}
if (i_size_read(inode) > 0) {
ret = btrfs_check_trunc_cache_free_space(fs_info,
&fs_info->global_block_rsv);
if (ret)
goto out_put;
ret = btrfs_truncate_free_space_cache(trans, NULL, inode);
if (ret)
goto out_put;
}
spin_lock(&block_group->lock);
if (block_group->cached != BTRFS_CACHE_FINISHED ||
!btrfs_test_opt(fs_info, SPACE_CACHE)) {
/*
* don't bother trying to write stuff out _if_
* a) we're not cached,
* b) we're with nospace_cache mount option,
* c) we're with v2 space_cache (FREE_SPACE_TREE).
*/
dcs = BTRFS_DC_WRITTEN;
spin_unlock(&block_group->lock);
goto out_put;
}
spin_unlock(&block_group->lock);
/*
* We hit an ENOSPC when setting up the cache in this transaction, just
* skip doing the setup, we've already cleared the cache so we're safe.
*/
if (test_bit(BTRFS_TRANS_CACHE_ENOSPC, &trans->transaction->flags)) {
ret = -ENOSPC;
goto out_put;
}
/*
* Try to preallocate enough space based on how big the block group is.
* Keep in mind this has to include any pinned space which could end up
* taking up quite a bit since it's not folded into the other space
* cache.
*/
cache_size = div_u64(block_group->length, SZ_256M);
if (!cache_size)
cache_size = 1;
cache_size *= 16;
cache_size *= fs_info->sectorsize;
ret = btrfs_check_data_free_space(BTRFS_I(inode), &data_reserved, 0,
cache_size, false);
if (ret)
goto out_put;
ret = btrfs_prealloc_file_range_trans(inode, trans, 0, 0, cache_size,
cache_size, cache_size,
&alloc_hint);
/*
* Our cache requires contiguous chunks so that we don't modify a bunch
* of metadata or split extents when writing the cache out, which means
* we can enospc if we are heavily fragmented in addition to just normal
* out of space conditions. So if we hit this just skip setting up any
* other block groups for this transaction, maybe we'll unpin enough
* space the next time around.
*/
if (!ret)
dcs = BTRFS_DC_SETUP;
else if (ret == -ENOSPC)
set_bit(BTRFS_TRANS_CACHE_ENOSPC, &trans->transaction->flags);
out_put:
iput(inode);
out_free:
btrfs_release_path(path);
out:
spin_lock(&block_group->lock);
if (!ret && dcs == BTRFS_DC_SETUP)
block_group->cache_generation = trans->transid;
block_group->disk_cache_state = dcs;
spin_unlock(&block_group->lock);
extent_changeset_free(data_reserved);
return ret;
}
int btrfs_setup_space_cache(struct btrfs_trans_handle *trans)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_block_group *cache, *tmp;
struct btrfs_transaction *cur_trans = trans->transaction;
struct btrfs_path *path;
if (list_empty(&cur_trans->dirty_bgs) ||
!btrfs_test_opt(fs_info, SPACE_CACHE))
return 0;
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
/* Could add new block groups, use _safe just in case */
list_for_each_entry_safe(cache, tmp, &cur_trans->dirty_bgs,
dirty_list) {
if (cache->disk_cache_state == BTRFS_DC_CLEAR)
cache_save_setup(cache, trans, path);
}
btrfs_free_path(path);
return 0;
}
/*
* Transaction commit does final block group cache writeback during a critical
* section where nothing is allowed to change the FS. This is required in
* order for the cache to actually match the block group, but can introduce a
* lot of latency into the commit.
*
* So, btrfs_start_dirty_block_groups is here to kick off block group cache IO.
* There's a chance we'll have to redo some of it if the block group changes
* again during the commit, but it greatly reduces the commit latency by
* getting rid of the easy block groups while we're still allowing others to
* join the commit.
*/
int btrfs_start_dirty_block_groups(struct btrfs_trans_handle *trans)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_block_group *cache;
struct btrfs_transaction *cur_trans = trans->transaction;
int ret = 0;
int should_put;
struct btrfs_path *path = NULL;
LIST_HEAD(dirty);
struct list_head *io = &cur_trans->io_bgs;
int loops = 0;
spin_lock(&cur_trans->dirty_bgs_lock);
if (list_empty(&cur_trans->dirty_bgs)) {
spin_unlock(&cur_trans->dirty_bgs_lock);
return 0;
}
list_splice_init(&cur_trans->dirty_bgs, &dirty);
spin_unlock(&cur_trans->dirty_bgs_lock);
again:
/* Make sure all the block groups on our dirty list actually exist */
btrfs_create_pending_block_groups(trans);
if (!path) {
path = btrfs_alloc_path();
if (!path) {
ret = -ENOMEM;
goto out;
}
}
/*
* cache_write_mutex is here only to save us from balance or automatic
* removal of empty block groups deleting this block group while we are
* writing out the cache
*/
mutex_lock(&trans->transaction->cache_write_mutex);
while (!list_empty(&dirty)) {
bool drop_reserve = true;
cache = list_first_entry(&dirty, struct btrfs_block_group,
dirty_list);
/*
* This can happen if something re-dirties a block group that
* is already under IO. Just wait for it to finish and then do
* it all again
*/
if (!list_empty(&cache->io_list)) {
list_del_init(&cache->io_list);
btrfs_wait_cache_io(trans, cache, path);
btrfs_put_block_group(cache);
}
/*
* btrfs_wait_cache_io uses the cache->dirty_list to decide if
* it should update the cache_state. Don't delete until after
* we wait.
*
* Since we're not running in the commit critical section
* we need the dirty_bgs_lock to protect from update_block_group
*/
spin_lock(&cur_trans->dirty_bgs_lock);
list_del_init(&cache->dirty_list);
spin_unlock(&cur_trans->dirty_bgs_lock);
should_put = 1;
cache_save_setup(cache, trans, path);
if (cache->disk_cache_state == BTRFS_DC_SETUP) {
cache->io_ctl.inode = NULL;
ret = btrfs_write_out_cache(trans, cache, path);
if (ret == 0 && cache->io_ctl.inode) {
should_put = 0;
/*
* The cache_write_mutex is protecting the
* io_list, also refer to the definition of
* btrfs_transaction::io_bgs for more details
*/
list_add_tail(&cache->io_list, io);
} else {
/*
* If we failed to write the cache, the
* generation will be bad and life goes on
*/
ret = 0;
}
}
if (!ret) {
ret = update_block_group_item(trans, path, cache);
/*
* Our block group might still be attached to the list
* of new block groups in the transaction handle of some
* other task (struct btrfs_trans_handle->new_bgs). This
* means its block group item isn't yet in the extent
* tree. If this happens ignore the error, as we will
* try again later in the critical section of the
* transaction commit.
*/
if (ret == -ENOENT) {
ret = 0;
spin_lock(&cur_trans->dirty_bgs_lock);
if (list_empty(&cache->dirty_list)) {
list_add_tail(&cache->dirty_list,
&cur_trans->dirty_bgs);
btrfs_get_block_group(cache);
drop_reserve = false;
}
spin_unlock(&cur_trans->dirty_bgs_lock);
} else if (ret) {
btrfs_abort_transaction(trans, ret);
}
}
/* If it's not on the io list, we need to put the block group */
if (should_put)
btrfs_put_block_group(cache);
if (drop_reserve)
btrfs_dec_delayed_refs_rsv_bg_updates(fs_info);
/*
* Avoid blocking other tasks for too long. It might even save
* us from writing caches for block groups that are going to be
* removed.
*/
mutex_unlock(&trans->transaction->cache_write_mutex);
if (ret)
goto out;
mutex_lock(&trans->transaction->cache_write_mutex);
}
mutex_unlock(&trans->transaction->cache_write_mutex);
/*
* Go through delayed refs for all the stuff we've just kicked off
* and then loop back (just once)
*/
if (!ret)
ret = btrfs_run_delayed_refs(trans, 0);
if (!ret && loops == 0) {
loops++;
spin_lock(&cur_trans->dirty_bgs_lock);
list_splice_init(&cur_trans->dirty_bgs, &dirty);
/*
* dirty_bgs_lock protects us from concurrent block group
* deletes too (not just cache_write_mutex).
*/
if (!list_empty(&dirty)) {
spin_unlock(&cur_trans->dirty_bgs_lock);
goto again;
}
spin_unlock(&cur_trans->dirty_bgs_lock);
}
out:
if (ret < 0) {
spin_lock(&cur_trans->dirty_bgs_lock);
list_splice_init(&dirty, &cur_trans->dirty_bgs);
spin_unlock(&cur_trans->dirty_bgs_lock);
btrfs_cleanup_dirty_bgs(cur_trans, fs_info);
}
btrfs_free_path(path);
return ret;
}
int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_block_group *cache;
struct btrfs_transaction *cur_trans = trans->transaction;
int ret = 0;
int should_put;
struct btrfs_path *path;
struct list_head *io = &cur_trans->io_bgs;
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
/*
* Even though we are in the critical section of the transaction commit,
* we can still have concurrent tasks adding elements to this
* transaction's list of dirty block groups. These tasks correspond to
* endio free space workers started when writeback finishes for a
* space cache, which run inode.c:btrfs_finish_ordered_io(), and can
* allocate new block groups as a result of COWing nodes of the root
* tree when updating the free space inode. The writeback for the space
* caches is triggered by an earlier call to
* btrfs_start_dirty_block_groups() and iterations of the following
* loop.
* Also we want to do the cache_save_setup first and then run the
* delayed refs to make sure we have the best chance at doing this all
* in one shot.
*/
spin_lock(&cur_trans->dirty_bgs_lock);
while (!list_empty(&cur_trans->dirty_bgs)) {
cache = list_first_entry(&cur_trans->dirty_bgs,
struct btrfs_block_group,
dirty_list);
/*
* This can happen if cache_save_setup re-dirties a block group
* that is already under IO. Just wait for it to finish and
* then do it all again
*/
if (!list_empty(&cache->io_list)) {
spin_unlock(&cur_trans->dirty_bgs_lock);
list_del_init(&cache->io_list);
btrfs_wait_cache_io(trans, cache, path);
btrfs_put_block_group(cache);
spin_lock(&cur_trans->dirty_bgs_lock);
}
/*
* Don't remove from the dirty list until after we've waited on
* any pending IO
*/
list_del_init(&cache->dirty_list);
spin_unlock(&cur_trans->dirty_bgs_lock);
should_put = 1;
cache_save_setup(cache, trans, path);
if (!ret)
ret = btrfs_run_delayed_refs(trans, U64_MAX);
if (!ret && cache->disk_cache_state == BTRFS_DC_SETUP) {
cache->io_ctl.inode = NULL;
ret = btrfs_write_out_cache(trans, cache, path);
if (ret == 0 && cache->io_ctl.inode) {
should_put = 0;
list_add_tail(&cache->io_list, io);
} else {
/*
* If we failed to write the cache, the
* generation will be bad and life goes on
*/
ret = 0;
}
}
if (!ret) {
ret = update_block_group_item(trans, path, cache);
/*
* One of the free space endio workers might have
* created a new block group while updating a free space
* cache's inode (at inode.c:btrfs_finish_ordered_io())
* and hasn't released its transaction handle yet, in
* which case the new block group is still attached to
* its transaction handle and its creation has not
* finished yet (no block group item in the extent tree
* yet, etc). If this is the case, wait for all free
* space endio workers to finish and retry. This is a
* very rare case so no need for a more efficient and
* complex approach.
*/
if (ret == -ENOENT) {
wait_event(cur_trans->writer_wait,
atomic_read(&cur_trans->num_writers) == 1);
ret = update_block_group_item(trans, path, cache);
}
if (ret)
btrfs_abort_transaction(trans, ret);
}
/* If its not on the io list, we need to put the block group */
if (should_put)
btrfs_put_block_group(cache);
btrfs_dec_delayed_refs_rsv_bg_updates(fs_info);
spin_lock(&cur_trans->dirty_bgs_lock);
}
spin_unlock(&cur_trans->dirty_bgs_lock);
/*
* Refer to the definition of io_bgs member for details why it's safe
* to use it without any locking
*/
while (!list_empty(io)) {
cache = list_first_entry(io, struct btrfs_block_group,
io_list);
list_del_init(&cache->io_list);
btrfs_wait_cache_io(trans, cache, path);
btrfs_put_block_group(cache);
}
btrfs_free_path(path);
return ret;
}
int btrfs_update_block_group(struct btrfs_trans_handle *trans,
u64 bytenr, u64 num_bytes, bool alloc)
{
struct btrfs_fs_info *info = trans->fs_info;
struct btrfs_space_info *space_info;
struct btrfs_block_group *cache;
u64 old_val;
bool reclaim = false;
bool bg_already_dirty = true;
int factor;
/* Block accounting for super block */
spin_lock(&info->delalloc_root_lock);
old_val = btrfs_super_bytes_used(info->super_copy);
if (alloc)
old_val += num_bytes;
else
old_val -= num_bytes;
btrfs_set_super_bytes_used(info->super_copy, old_val);
spin_unlock(&info->delalloc_root_lock);
cache = btrfs_lookup_block_group(info, bytenr);
if (!cache)
return -ENOENT;
/* An extent can not span multiple block groups. */
ASSERT(bytenr + num_bytes <= cache->start + cache->length);
space_info = cache->space_info;
factor = btrfs_bg_type_to_factor(cache->flags);
/*
* If this block group has free space cache written out, we need to make
* sure to load it if we are removing space. This is because we need
* the unpinning stage to actually add the space back to the block group,
* otherwise we will leak space.
*/
if (!alloc && !btrfs_block_group_done(cache))
btrfs_cache_block_group(cache, true);
spin_lock(&space_info->lock);
spin_lock(&cache->lock);
if (btrfs_test_opt(info, SPACE_CACHE) &&
cache->disk_cache_state < BTRFS_DC_CLEAR)
cache->disk_cache_state = BTRFS_DC_CLEAR;
old_val = cache->used;
if (alloc) {
old_val += num_bytes;
cache->used = old_val;
cache->reserved -= num_bytes;
space_info->bytes_reserved -= num_bytes;
space_info->bytes_used += num_bytes;
space_info->disk_used += num_bytes * factor;
spin_unlock(&cache->lock);
spin_unlock(&space_info->lock);
} else {
old_val -= num_bytes;
cache->used = old_val;
cache->pinned += num_bytes;
btrfs_space_info_update_bytes_pinned(info, space_info, num_bytes);
space_info->bytes_used -= num_bytes;
space_info->disk_used -= num_bytes * factor;
reclaim = should_reclaim_block_group(cache, num_bytes);
spin_unlock(&cache->lock);
spin_unlock(&space_info->lock);
set_extent_bit(&trans->transaction->pinned_extents, bytenr,
bytenr + num_bytes - 1, EXTENT_DIRTY, NULL);
}
spin_lock(&trans->transaction->dirty_bgs_lock);
if (list_empty(&cache->dirty_list)) {
list_add_tail(&cache->dirty_list, &trans->transaction->dirty_bgs);
bg_already_dirty = false;
btrfs_get_block_group(cache);
}
spin_unlock(&trans->transaction->dirty_bgs_lock);
/*
* No longer have used bytes in this block group, queue it for deletion.
* We do this after adding the block group to the dirty list to avoid
* races between cleaner kthread and space cache writeout.
*/
if (!alloc && old_val == 0) {
if (!btrfs_test_opt(info, DISCARD_ASYNC))
btrfs_mark_bg_unused(cache);
} else if (!alloc && reclaim) {
btrfs_mark_bg_to_reclaim(cache);
}
btrfs_put_block_group(cache);
/* Modified block groups are accounted for in the delayed_refs_rsv. */
if (!bg_already_dirty)
btrfs_inc_delayed_refs_rsv_bg_updates(info);
return 0;
}
/*
* Update the block_group and space info counters.
*
* @cache: The cache we are manipulating
* @ram_bytes: The number of bytes of file content, and will be same to
* @num_bytes except for the compress path.
* @num_bytes: The number of bytes in question
* @delalloc: The blocks are allocated for the delalloc write
*
* This is called by the allocator when it reserves space. If this is a
* reservation and the block group has become read only we cannot make the
* reservation and return -EAGAIN, otherwise this function always succeeds.
*/
int btrfs_add_reserved_bytes(struct btrfs_block_group *cache,
u64 ram_bytes, u64 num_bytes, int delalloc,
bool force_wrong_size_class)
{
struct btrfs_space_info *space_info = cache->space_info;
enum btrfs_block_group_size_class size_class;
int ret = 0;
spin_lock(&space_info->lock);
spin_lock(&cache->lock);
if (cache->ro) {
ret = -EAGAIN;
goto out;
}
if (btrfs_block_group_should_use_size_class(cache)) {
size_class = btrfs_calc_block_group_size_class(num_bytes);
ret = btrfs_use_block_group_size_class(cache, size_class, force_wrong_size_class);
if (ret)
goto out;
}
cache->reserved += num_bytes;
space_info->bytes_reserved += num_bytes;
trace_btrfs_space_reservation(cache->fs_info, "space_info",
space_info->flags, num_bytes, 1);
btrfs_space_info_update_bytes_may_use(cache->fs_info,
space_info, -ram_bytes);
if (delalloc)
cache->delalloc_bytes += num_bytes;
/*
* Compression can use less space than we reserved, so wake tickets if
* that happens.
*/
if (num_bytes < ram_bytes)
btrfs_try_granting_tickets(cache->fs_info, space_info);
out:
spin_unlock(&cache->lock);
spin_unlock(&space_info->lock);
return ret;
}
/*
* Update the block_group and space info counters.
*
* @cache: The cache we are manipulating
* @num_bytes: The number of bytes in question
* @delalloc: The blocks are allocated for the delalloc write
*
* This is called by somebody who is freeing space that was never actually used
* on disk. For example if you reserve some space for a new leaf in transaction
* A and before transaction A commits you free that leaf, you call this with
* reserve set to 0 in order to clear the reservation.
*/
void btrfs_free_reserved_bytes(struct btrfs_block_group *cache,
u64 num_bytes, int delalloc)
{
struct btrfs_space_info *space_info = cache->space_info;
spin_lock(&space_info->lock);
spin_lock(&cache->lock);
if (cache->ro)
space_info->bytes_readonly += num_bytes;
cache->reserved -= num_bytes;
space_info->bytes_reserved -= num_bytes;
space_info->max_extent_size = 0;
if (delalloc)
cache->delalloc_bytes -= num_bytes;
spin_unlock(&cache->lock);
btrfs_try_granting_tickets(cache->fs_info, space_info);
spin_unlock(&space_info->lock);
}
static void force_metadata_allocation(struct btrfs_fs_info *info)
{
struct list_head *head = &info->space_info;
struct btrfs_space_info *found;
list_for_each_entry(found, head, list) {
if (found->flags & BTRFS_BLOCK_GROUP_METADATA)
found->force_alloc = CHUNK_ALLOC_FORCE;
}
}
static int should_alloc_chunk(struct btrfs_fs_info *fs_info,
struct btrfs_space_info *sinfo, int force)
{
u64 bytes_used = btrfs_space_info_used(sinfo, false);
u64 thresh;
if (force == CHUNK_ALLOC_FORCE)
return 1;
/*
* in limited mode, we want to have some free space up to
* about 1% of the FS size.
*/
if (force == CHUNK_ALLOC_LIMITED) {
thresh = btrfs_super_total_bytes(fs_info->super_copy);
thresh = max_t(u64, SZ_64M, mult_perc(thresh, 1));
if (sinfo->total_bytes - bytes_used < thresh)
return 1;
}
if (bytes_used + SZ_2M < mult_perc(sinfo->total_bytes, 80))
return 0;
return 1;
}
int btrfs_force_chunk_alloc(struct btrfs_trans_handle *trans, u64 type)
{
u64 alloc_flags = btrfs_get_alloc_profile(trans->fs_info, type);
return btrfs_chunk_alloc(trans, alloc_flags, CHUNK_ALLOC_FORCE);
}
static struct btrfs_block_group *do_chunk_alloc(struct btrfs_trans_handle *trans, u64 flags)
{
struct btrfs_block_group *bg;
int ret;
/*
* Check if we have enough space in the system space info because we
* will need to update device items in the chunk btree and insert a new
* chunk item in the chunk btree as well. This will allocate a new
* system block group if needed.
*/
check_system_chunk(trans, flags);
bg = btrfs_create_chunk(trans, flags);
if (IS_ERR(bg)) {
ret = PTR_ERR(bg);
goto out;
}
ret = btrfs_chunk_alloc_add_chunk_item(trans, bg);
/*
* Normally we are not expected to fail with -ENOSPC here, since we have
* previously reserved space in the system space_info and allocated one
* new system chunk if necessary. However there are three exceptions:
*
* 1) We may have enough free space in the system space_info but all the
* existing system block groups have a profile which can not be used
* for extent allocation.
*
* This happens when mounting in degraded mode. For example we have a
* RAID1 filesystem with 2 devices, lose one device and mount the fs
* using the other device in degraded mode. If we then allocate a chunk,
* we may have enough free space in the existing system space_info, but
* none of the block groups can be used for extent allocation since they
* have a RAID1 profile, and because we are in degraded mode with a
* single device, we are forced to allocate a new system chunk with a
* SINGLE profile. Making check_system_chunk() iterate over all system
* block groups and check if they have a usable profile and enough space
* can be slow on very large filesystems, so we tolerate the -ENOSPC and
* try again after forcing allocation of a new system chunk. Like this
* we avoid paying the cost of that search in normal circumstances, when
* we were not mounted in degraded mode;
*
* 2) We had enough free space info the system space_info, and one suitable
* block group to allocate from when we called check_system_chunk()
* above. However right after we called it, the only system block group
* with enough free space got turned into RO mode by a running scrub,
* and in this case we have to allocate a new one and retry. We only
* need do this allocate and retry once, since we have a transaction
* handle and scrub uses the commit root to search for block groups;
*
* 3) We had one system block group with enough free space when we called
* check_system_chunk(), but after that, right before we tried to
* allocate the last extent buffer we needed, a discard operation came
* in and it temporarily removed the last free space entry from the
* block group (discard removes a free space entry, discards it, and
* then adds back the entry to the block group cache).
*/
if (ret == -ENOSPC) {
const u64 sys_flags = btrfs_system_alloc_profile(trans->fs_info);
struct btrfs_block_group *sys_bg;
sys_bg = btrfs_create_chunk(trans, sys_flags);
if (IS_ERR(sys_bg)) {
ret = PTR_ERR(sys_bg);
btrfs_abort_transaction(trans, ret);
goto out;
}
ret = btrfs_chunk_alloc_add_chunk_item(trans, sys_bg);
if (ret) {
btrfs_abort_transaction(trans, ret);
goto out;
}
ret = btrfs_chunk_alloc_add_chunk_item(trans, bg);
if (ret) {
btrfs_abort_transaction(trans, ret);
goto out;
}
} else if (ret) {
btrfs_abort_transaction(trans, ret);
goto out;
}
out:
btrfs_trans_release_chunk_metadata(trans);
if (ret)
return ERR_PTR(ret);
btrfs_get_block_group(bg);
return bg;
}
/*
* Chunk allocation is done in 2 phases:
*
* 1) Phase 1 - through btrfs_chunk_alloc() we allocate device extents for
* the chunk, the chunk mapping, create its block group and add the items
* that belong in the chunk btree to it - more specifically, we need to
* update device items in the chunk btree and add a new chunk item to it.
*
* 2) Phase 2 - through btrfs_create_pending_block_groups(), we add the block
* group item to the extent btree and the device extent items to the devices
* btree.
*
* This is done to prevent deadlocks. For example when COWing a node from the
* extent btree we are holding a write lock on the node's parent and if we
* trigger chunk allocation and attempted to insert the new block group item
* in the extent btree right way, we could deadlock because the path for the
* insertion can include that parent node. At first glance it seems impossible
* to trigger chunk allocation after starting a transaction since tasks should
* reserve enough transaction units (metadata space), however while that is true
* most of the time, chunk allocation may still be triggered for several reasons:
*
* 1) When reserving metadata, we check if there is enough free space in the
* metadata space_info and therefore don't trigger allocation of a new chunk.
* However later when the task actually tries to COW an extent buffer from
* the extent btree or from the device btree for example, it is forced to
* allocate a new block group (chunk) because the only one that had enough
* free space was just turned to RO mode by a running scrub for example (or
* device replace, block group reclaim thread, etc), so we can not use it
* for allocating an extent and end up being forced to allocate a new one;
*
* 2) Because we only check that the metadata space_info has enough free bytes,
* we end up not allocating a new metadata chunk in that case. However if
* the filesystem was mounted in degraded mode, none of the existing block
* groups might be suitable for extent allocation due to their incompatible
* profile (for e.g. mounting a 2 devices filesystem, where all block groups
* use a RAID1 profile, in degraded mode using a single device). In this case
* when the task attempts to COW some extent buffer of the extent btree for
* example, it will trigger allocation of a new metadata block group with a
* suitable profile (SINGLE profile in the example of the degraded mount of
* the RAID1 filesystem);
*
* 3) The task has reserved enough transaction units / metadata space, but when
* it attempts to COW an extent buffer from the extent or device btree for
* example, it does not find any free extent in any metadata block group,
* therefore forced to try to allocate a new metadata block group.
* This is because some other task allocated all available extents in the
* meanwhile - this typically happens with tasks that don't reserve space
* properly, either intentionally or as a bug. One example where this is
* done intentionally is fsync, as it does not reserve any transaction units
* and ends up allocating a variable number of metadata extents for log
* tree extent buffers;
*
* 4) The task has reserved enough transaction units / metadata space, but right
* before it tries to allocate the last extent buffer it needs, a discard
* operation comes in and, temporarily, removes the last free space entry from
* the only metadata block group that had free space (discard starts by
* removing a free space entry from a block group, then does the discard
* operation and, once it's done, it adds back the free space entry to the
* block group).
*
* We also need this 2 phases setup when adding a device to a filesystem with
* a seed device - we must create new metadata and system chunks without adding
* any of the block group items to the chunk, extent and device btrees. If we
* did not do it this way, we would get ENOSPC when attempting to update those
* btrees, since all the chunks from the seed device are read-only.
*
* Phase 1 does the updates and insertions to the chunk btree because if we had
* it done in phase 2 and have a thundering herd of tasks allocating chunks in
* parallel, we risk having too many system chunks allocated by many tasks if
* many tasks reach phase 1 without the previous ones completing phase 2. In the
* extreme case this leads to exhaustion of the system chunk array in the
* superblock. This is easier to trigger if using a btree node/leaf size of 64K
* and with RAID filesystems (so we have more device items in the chunk btree).
* This has happened before and commit eafa4fd0ad0607 ("btrfs: fix exhaustion of
* the system chunk array due to concurrent allocations") provides more details.
*
* Allocation of system chunks does not happen through this function. A task that
* needs to update the chunk btree (the only btree that uses system chunks), must
* preallocate chunk space by calling either check_system_chunk() or
* btrfs_reserve_chunk_metadata() - the former is used when allocating a data or
* metadata chunk or when removing a chunk, while the later is used before doing
* a modification to the chunk btree - use cases for the later are adding,
* removing and resizing a device as well as relocation of a system chunk.
* See the comment below for more details.
*
* The reservation of system space, done through check_system_chunk(), as well
* as all the updates and insertions into the chunk btree must be done while
* holding fs_info->chunk_mutex. This is important to guarantee that while COWing
* an extent buffer from the chunks btree we never trigger allocation of a new
* system chunk, which would result in a deadlock (trying to lock twice an
* extent buffer of the chunk btree, first time before triggering the chunk
* allocation and the second time during chunk allocation while attempting to
* update the chunks btree). The system chunk array is also updated while holding
* that mutex. The same logic applies to removing chunks - we must reserve system
* space, update the chunk btree and the system chunk array in the superblock
* while holding fs_info->chunk_mutex.
*
* This function, btrfs_chunk_alloc(), belongs to phase 1.
*
* If @force is CHUNK_ALLOC_FORCE:
* - return 1 if it successfully allocates a chunk,
* - return errors including -ENOSPC otherwise.
* If @force is NOT CHUNK_ALLOC_FORCE:
* - return 0 if it doesn't need to allocate a new chunk,
* - return 1 if it successfully allocates a chunk,
* - return errors including -ENOSPC otherwise.
*/
int btrfs_chunk_alloc(struct btrfs_trans_handle *trans, u64 flags,
enum btrfs_chunk_alloc_enum force)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_space_info *space_info;
struct btrfs_block_group *ret_bg;
bool wait_for_alloc = false;
bool should_alloc = false;
bool from_extent_allocation = false;
int ret = 0;
if (force == CHUNK_ALLOC_FORCE_FOR_EXTENT) {
from_extent_allocation = true;
force = CHUNK_ALLOC_FORCE;
}
/* Don't re-enter if we're already allocating a chunk */
if (trans->allocating_chunk)
return -ENOSPC;
/*
* Allocation of system chunks can not happen through this path, as we
* could end up in a deadlock if we are allocating a data or metadata
* chunk and there is another task modifying the chunk btree.
*
* This is because while we are holding the chunk mutex, we will attempt
* to add the new chunk item to the chunk btree or update an existing
* device item in the chunk btree, while the other task that is modifying
* the chunk btree is attempting to COW an extent buffer while holding a
* lock on it and on its parent - if the COW operation triggers a system
* chunk allocation, then we can deadlock because we are holding the
* chunk mutex and we may need to access that extent buffer or its parent
* in order to add the chunk item or update a device item.
*
* Tasks that want to modify the chunk tree should reserve system space
* before updating the chunk btree, by calling either
* btrfs_reserve_chunk_metadata() or check_system_chunk().
* It's possible that after a task reserves the space, it still ends up
* here - this happens in the cases described above at do_chunk_alloc().
* The task will have to either retry or fail.
*/
if (flags & BTRFS_BLOCK_GROUP_SYSTEM)
return -ENOSPC;
space_info = btrfs_find_space_info(fs_info, flags);
ASSERT(space_info);
do {
spin_lock(&space_info->lock);
if (force < space_info->force_alloc)
force = space_info->force_alloc;
should_alloc = should_alloc_chunk(fs_info, space_info, force);
if (space_info->full) {
/* No more free physical space */
if (should_alloc)
ret = -ENOSPC;
else
ret = 0;
spin_unlock(&space_info->lock);
return ret;
} else if (!should_alloc) {
spin_unlock(&space_info->lock);
return 0;
} else if (space_info->chunk_alloc) {
/*
* Someone is already allocating, so we need to block
* until this someone is finished and then loop to
* recheck if we should continue with our allocation
* attempt.
*/
wait_for_alloc = true;
force = CHUNK_ALLOC_NO_FORCE;
spin_unlock(&space_info->lock);
mutex_lock(&fs_info->chunk_mutex);
mutex_unlock(&fs_info->chunk_mutex);
} else {
/* Proceed with allocation */
space_info->chunk_alloc = 1;
wait_for_alloc = false;
spin_unlock(&space_info->lock);
}
cond_resched();
} while (wait_for_alloc);
mutex_lock(&fs_info->chunk_mutex);
trans->allocating_chunk = true;
/*
* If we have mixed data/metadata chunks we want to make sure we keep
* allocating mixed chunks instead of individual chunks.
*/
if (btrfs_mixed_space_info(space_info))
flags |= (BTRFS_BLOCK_GROUP_DATA | BTRFS_BLOCK_GROUP_METADATA);
/*
* if we're doing a data chunk, go ahead and make sure that
* we keep a reasonable number of metadata chunks allocated in the
* FS as well.
*/
if (flags & BTRFS_BLOCK_GROUP_DATA && fs_info->metadata_ratio) {
fs_info->data_chunk_allocations++;
if (!(fs_info->data_chunk_allocations %
fs_info->metadata_ratio))
force_metadata_allocation(fs_info);
}
ret_bg = do_chunk_alloc(trans, flags);
trans->allocating_chunk = false;
if (IS_ERR(ret_bg)) {
ret = PTR_ERR(ret_bg);
} else if (from_extent_allocation && (flags & BTRFS_BLOCK_GROUP_DATA)) {
/*
* New block group is likely to be used soon. Try to activate
* it now. Failure is OK for now.
*/
btrfs_zone_activate(ret_bg);
}
if (!ret)
btrfs_put_block_group(ret_bg);
spin_lock(&space_info->lock);
if (ret < 0) {
if (ret == -ENOSPC)
space_info->full = 1;
else
goto out;
} else {
ret = 1;
space_info->max_extent_size = 0;
}
space_info->force_alloc = CHUNK_ALLOC_NO_FORCE;
out:
space_info->chunk_alloc = 0;
spin_unlock(&space_info->lock);
mutex_unlock(&fs_info->chunk_mutex);
return ret;
}
static u64 get_profile_num_devs(struct btrfs_fs_info *fs_info, u64 type)
{
u64 num_dev;
num_dev = btrfs_raid_array[btrfs_bg_flags_to_raid_index(type)].devs_max;
if (!num_dev)
num_dev = fs_info->fs_devices->rw_devices;
return num_dev;
}
static void reserve_chunk_space(struct btrfs_trans_handle *trans,
u64 bytes,
u64 type)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_space_info *info;
u64 left;
int ret = 0;
/*
* Needed because we can end up allocating a system chunk and for an
* atomic and race free space reservation in the chunk block reserve.
*/
lockdep_assert_held(&fs_info->chunk_mutex);
info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_SYSTEM);
spin_lock(&info->lock);
left = info->total_bytes - btrfs_space_info_used(info, true);
spin_unlock(&info->lock);
if (left < bytes && btrfs_test_opt(fs_info, ENOSPC_DEBUG)) {
btrfs_info(fs_info, "left=%llu, need=%llu, flags=%llu",
left, bytes, type);
btrfs_dump_space_info(fs_info, info, 0, 0);
}
if (left < bytes) {
u64 flags = btrfs_system_alloc_profile(fs_info);
struct btrfs_block_group *bg;
/*
* Ignore failure to create system chunk. We might end up not
* needing it, as we might not need to COW all nodes/leafs from
* the paths we visit in the chunk tree (they were already COWed
* or created in the current transaction for example).
*/
bg = btrfs_create_chunk(trans, flags);
if (IS_ERR(bg)) {
ret = PTR_ERR(bg);
} else {
/*
* We have a new chunk. We also need to activate it for
* zoned filesystem.
*/
ret = btrfs_zoned_activate_one_bg(fs_info, info, true);
if (ret < 0)
return;
/*
* If we fail to add the chunk item here, we end up
* trying again at phase 2 of chunk allocation, at
* btrfs_create_pending_block_groups(). So ignore
* any error here. An ENOSPC here could happen, due to
* the cases described at do_chunk_alloc() - the system
* block group we just created was just turned into RO
* mode by a scrub for example, or a running discard
* temporarily removed its free space entries, etc.
*/
btrfs_chunk_alloc_add_chunk_item(trans, bg);
}
}
if (!ret) {
ret = btrfs_block_rsv_add(fs_info,
&fs_info->chunk_block_rsv,
bytes, BTRFS_RESERVE_NO_FLUSH);
if (!ret)
trans->chunk_bytes_reserved += bytes;
}
}
/*
* Reserve space in the system space for allocating or removing a chunk.
* The caller must be holding fs_info->chunk_mutex.
*/
void check_system_chunk(struct btrfs_trans_handle *trans, u64 type)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
const u64 num_devs = get_profile_num_devs(fs_info, type);
u64 bytes;
/* num_devs device items to update and 1 chunk item to add or remove. */
bytes = btrfs_calc_metadata_size(fs_info, num_devs) +
btrfs_calc_insert_metadata_size(fs_info, 1);
reserve_chunk_space(trans, bytes, type);
}
/*
* Reserve space in the system space, if needed, for doing a modification to the
* chunk btree.
*
* @trans: A transaction handle.
* @is_item_insertion: Indicate if the modification is for inserting a new item
* in the chunk btree or if it's for the deletion or update
* of an existing item.
*
* This is used in a context where we need to update the chunk btree outside
* block group allocation and removal, to avoid a deadlock with a concurrent
* task that is allocating a metadata or data block group and therefore needs to
* update the chunk btree while holding the chunk mutex. After the update to the
* chunk btree is done, btrfs_trans_release_chunk_metadata() should be called.
*
*/
void btrfs_reserve_chunk_metadata(struct btrfs_trans_handle *trans,
bool is_item_insertion)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
u64 bytes;
if (is_item_insertion)
bytes = btrfs_calc_insert_metadata_size(fs_info, 1);
else
bytes = btrfs_calc_metadata_size(fs_info, 1);
mutex_lock(&fs_info->chunk_mutex);
reserve_chunk_space(trans, bytes, BTRFS_BLOCK_GROUP_SYSTEM);
mutex_unlock(&fs_info->chunk_mutex);
}
void btrfs_put_block_group_cache(struct btrfs_fs_info *info)
{
struct btrfs_block_group *block_group;
block_group = btrfs_lookup_first_block_group(info, 0);
while (block_group) {
btrfs_wait_block_group_cache_done(block_group);
spin_lock(&block_group->lock);
if (test_and_clear_bit(BLOCK_GROUP_FLAG_IREF,
&block_group->runtime_flags)) {
struct inode *inode = block_group->inode;
block_group->inode = NULL;
spin_unlock(&block_group->lock);
ASSERT(block_group->io_ctl.inode == NULL);
iput(inode);
} else {
spin_unlock(&block_group->lock);
}
block_group = btrfs_next_block_group(block_group);
}
}
/*
* Must be called only after stopping all workers, since we could have block
* group caching kthreads running, and therefore they could race with us if we
* freed the block groups before stopping them.
*/
int btrfs_free_block_groups(struct btrfs_fs_info *info)
{
struct btrfs_block_group *block_group;
struct btrfs_space_info *space_info;
struct btrfs_caching_control *caching_ctl;
struct rb_node *n;
if (btrfs_is_zoned(info)) {
if (info->active_meta_bg) {
btrfs_put_block_group(info->active_meta_bg);
info->active_meta_bg = NULL;
}
if (info->active_system_bg) {
btrfs_put_block_group(info->active_system_bg);
info->active_system_bg = NULL;
}
}
write_lock(&info->block_group_cache_lock);
while (!list_empty(&info->caching_block_groups)) {
caching_ctl = list_entry(info->caching_block_groups.next,
struct btrfs_caching_control, list);
list_del(&caching_ctl->list);
btrfs_put_caching_control(caching_ctl);
}
write_unlock(&info->block_group_cache_lock);
spin_lock(&info->unused_bgs_lock);
while (!list_empty(&info->unused_bgs)) {
block_group = list_first_entry(&info->unused_bgs,
struct btrfs_block_group,
bg_list);
list_del_init(&block_group->bg_list);
btrfs_put_block_group(block_group);
}
while (!list_empty(&info->reclaim_bgs)) {
block_group = list_first_entry(&info->reclaim_bgs,
struct btrfs_block_group,
bg_list);
list_del_init(&block_group->bg_list);
btrfs_put_block_group(block_group);
}
spin_unlock(&info->unused_bgs_lock);
spin_lock(&info->zone_active_bgs_lock);
while (!list_empty(&info->zone_active_bgs)) {
block_group = list_first_entry(&info->zone_active_bgs,
struct btrfs_block_group,
active_bg_list);
list_del_init(&block_group->active_bg_list);
btrfs_put_block_group(block_group);
}
spin_unlock(&info->zone_active_bgs_lock);
write_lock(&info->block_group_cache_lock);
while ((n = rb_last(&info->block_group_cache_tree.rb_root)) != NULL) {
block_group = rb_entry(n, struct btrfs_block_group,
cache_node);
rb_erase_cached(&block_group->cache_node,
&info->block_group_cache_tree);
RB_CLEAR_NODE(&block_group->cache_node);
write_unlock(&info->block_group_cache_lock);
down_write(&block_group->space_info->groups_sem);
list_del(&block_group->list);
up_write(&block_group->space_info->groups_sem);
/*
* We haven't cached this block group, which means we could
* possibly have excluded extents on this block group.
*/
if (block_group->cached == BTRFS_CACHE_NO ||
block_group->cached == BTRFS_CACHE_ERROR)
btrfs_free_excluded_extents(block_group);
btrfs_remove_free_space_cache(block_group);
ASSERT(block_group->cached != BTRFS_CACHE_STARTED);
ASSERT(list_empty(&block_group->dirty_list));
ASSERT(list_empty(&block_group->io_list));
ASSERT(list_empty(&block_group->bg_list));
ASSERT(refcount_read(&block_group->refs) == 1);
ASSERT(block_group->swap_extents == 0);
btrfs_put_block_group(block_group);
write_lock(&info->block_group_cache_lock);
}
write_unlock(&info->block_group_cache_lock);
btrfs_release_global_block_rsv(info);
while (!list_empty(&info->space_info)) {
space_info = list_entry(info->space_info.next,
struct btrfs_space_info,
list);
/*
* Do not hide this behind enospc_debug, this is actually
* important and indicates a real bug if this happens.
*/
if (WARN_ON(space_info->bytes_pinned > 0 ||
space_info->bytes_may_use > 0))
btrfs_dump_space_info(info, space_info, 0, 0);
/*
* If there was a failure to cleanup a log tree, very likely due
* to an IO failure on a writeback attempt of one or more of its
* extent buffers, we could not do proper (and cheap) unaccounting
* of their reserved space, so don't warn on bytes_reserved > 0 in
* that case.
*/
if (!(space_info->flags & BTRFS_BLOCK_GROUP_METADATA) ||
!BTRFS_FS_LOG_CLEANUP_ERROR(info)) {
if (WARN_ON(space_info->bytes_reserved > 0))
btrfs_dump_space_info(info, space_info, 0, 0);
}
WARN_ON(space_info->reclaim_size > 0);
list_del(&space_info->list);
btrfs_sysfs_remove_space_info(space_info);
}
return 0;
}
void btrfs_freeze_block_group(struct btrfs_block_group *cache)
{
atomic_inc(&cache->frozen);
}
void btrfs_unfreeze_block_group(struct btrfs_block_group *block_group)
{
struct btrfs_fs_info *fs_info = block_group->fs_info;
bool cleanup;
spin_lock(&block_group->lock);
cleanup = (atomic_dec_and_test(&block_group->frozen) &&
test_bit(BLOCK_GROUP_FLAG_REMOVED, &block_group->runtime_flags));
spin_unlock(&block_group->lock);
if (cleanup) {
struct btrfs_chunk_map *map;
map = btrfs_find_chunk_map(fs_info, block_group->start, 1);
/* Logic error, can't happen. */
ASSERT(map);
btrfs_remove_chunk_map(fs_info, map);
/* Once for our lookup reference. */
btrfs_free_chunk_map(map);
/*
* We may have left one free space entry and other possible
* tasks trimming this block group have left 1 entry each one.
* Free them if any.
*/
btrfs_remove_free_space_cache(block_group);
}
}
bool btrfs_inc_block_group_swap_extents(struct btrfs_block_group *bg)
{
bool ret = true;
spin_lock(&bg->lock);
if (bg->ro)
ret = false;
else
bg->swap_extents++;
spin_unlock(&bg->lock);
return ret;
}
void btrfs_dec_block_group_swap_extents(struct btrfs_block_group *bg, int amount)
{
spin_lock(&bg->lock);
ASSERT(!bg->ro);
ASSERT(bg->swap_extents >= amount);
bg->swap_extents -= amount;
spin_unlock(&bg->lock);
}
enum btrfs_block_group_size_class btrfs_calc_block_group_size_class(u64 size)
{
if (size <= SZ_128K)
return BTRFS_BG_SZ_SMALL;
if (size <= SZ_8M)
return BTRFS_BG_SZ_MEDIUM;
return BTRFS_BG_SZ_LARGE;
}
/*
* Handle a block group allocating an extent in a size class
*
* @bg: The block group we allocated in.
* @size_class: The size class of the allocation.
* @force_wrong_size_class: Whether we are desperate enough to allow
* mismatched size classes.
*
* Returns: 0 if the size class was valid for this block_group, -EAGAIN in the
* case of a race that leads to the wrong size class without
* force_wrong_size_class set.
*
* find_free_extent will skip block groups with a mismatched size class until
* it really needs to avoid ENOSPC. In that case it will set
* force_wrong_size_class. However, if a block group is newly allocated and
* doesn't yet have a size class, then it is possible for two allocations of
* different sizes to race and both try to use it. The loser is caught here and
* has to retry.
*/
int btrfs_use_block_group_size_class(struct btrfs_block_group *bg,
enum btrfs_block_group_size_class size_class,
bool force_wrong_size_class)
{
ASSERT(size_class != BTRFS_BG_SZ_NONE);
/* The new allocation is in the right size class, do nothing */
if (bg->size_class == size_class)
return 0;
/*
* The new allocation is in a mismatched size class.
* This means one of two things:
*
* 1. Two tasks in find_free_extent for different size_classes raced
* and hit the same empty block_group. Make the loser try again.
* 2. A call to find_free_extent got desperate enough to set
* 'force_wrong_slab'. Don't change the size_class, but allow the
* allocation.
*/
if (bg->size_class != BTRFS_BG_SZ_NONE) {
if (force_wrong_size_class)
return 0;
return -EAGAIN;
}
/*
* The happy new block group case: the new allocation is the first
* one in the block_group so we set size_class.
*/
bg->size_class = size_class;
return 0;
}
bool btrfs_block_group_should_use_size_class(struct btrfs_block_group *bg)
{
if (btrfs_is_zoned(bg->fs_info))
return false;
if (!btrfs_is_block_group_data_only(bg))
return false;
return true;
}