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linux/fs/btrfs/block-group.c
Qu Wenruo 7561551e7b btrfs: scrub: try harder to mark RAID56 block groups read-only 
Currently we allow a block group not to be marked read-only for scrub.

But for RAID56 block groups if we require the block group to be
read-only, then we're allowed to use cached content from scrub stripe to
reduce unnecessary RAID56 reads.

So this patch would:

- Make btrfs_inc_block_group_ro() try harder
  During my tests, for cases like btrfs/061 and btrfs/064, we can hit
  ENOSPC from btrfs_inc_block_group_ro() calls during scrub.

  The reason is if we only have one single data chunk, and trying to
  scrub it, we won't have any space left for any newer data writes.

  But this check should be done by the caller, especially for scrub
  cases we only temporarily mark the chunk read-only.
  And newer data writes would always try to allocate a new data chunk
  when needed.

- Return error for scrub if we failed to mark a RAID56 chunk read-only

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2023-05-17 11:59:46 +02:00

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// 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;
if (allowed & BTRFS_BLOCK_GROUP_RAID6)
allowed = BTRFS_BLOCK_GROUP_RAID6;
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_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);
kfree(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;
caching_ctl = btrfs_get_caching_control(cache);
if (!caching_ctl)
return;
wait_event(caching_ctl->wait, btrfs_block_group_done(cache) ||
(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
/*
* This is only called by btrfs_cache_block_group, since we could have freed
* extents we need to check the pinned_extents for any extents that can't be
* used yet since their free space will be released as soon as the transaction
* commits.
*/
u64 add_new_free_space(struct btrfs_block_group *block_group, u64 start, u64 end)
{
struct btrfs_fs_info *info = block_group->fs_info;
u64 extent_start, extent_end, size, total_added = 0;
int ret;
while (start < end) {
ret = find_first_extent_bit(&info->excluded_extents, start,
&extent_start, &extent_end,
EXTENT_DIRTY | EXTENT_UPTODATE,
NULL);
if (ret)
break;
if (extent_start <= start) {
start = extent_end + 1;
} else if (extent_start > start && extent_start < end) {
size = extent_start - start;
total_added += size;
ret = btrfs_add_free_space_async_trimmed(block_group,
start, size);
BUG_ON(ret); /* -ENOMEM or logic error */
start = extent_end + 1;
} else {
break;
}
}
if (start < end) {
size = end - start;
total_added += size;
ret = btrfs_add_free_space_async_trimmed(block_group, start,
size);
BUG_ON(ret); /* -ENOMEM or logic error */
}
return total_added;
}
/*
* 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) {
total_found += add_new_free_space(block_group, last,
key.objectid);
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)
wake_up(&caching_ctl->wait);
}
}
path->slots[0]++;
}
ret = 0;
total_found += add_new_free_space(block_group, last,
block_group->start + block_group->length);
out:
btrfs_free_path(path);
return ret;
}
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);
btrfs_init_work(&caching_ctl->work, caching_thread, NULL, 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,
u64 group_start, struct extent_map *em)
{
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_em;
bool remove_rsv = false;
block_group = btrfs_lookup_block_group(fs_info, group_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 extent 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_em = (atomic_read(&block_group->frozen) == 0);
spin_unlock(&block_group->lock);
if (remove_em) {
struct extent_map_tree *em_tree;
em_tree = &fs_info->mapping_tree;
write_lock(&em_tree->lock);
remove_extent_mapping(em_tree, em);
write_unlock(&em_tree->lock);
/* once for the tree */
free_extent_map(em);
}
out:
/* Once for the lookup reference */
btrfs_put_block_group(block_group);
if (remove_rsv)
btrfs_delayed_refs_rsv_release(fs_info, 1);
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 extent_map_tree *em_tree = &fs_info->mapping_tree;
struct extent_map *em;
struct map_lookup *map;
unsigned int num_items;
read_lock(&em_tree->lock);
em = lookup_extent_mapping(em_tree, chunk_offset, 1);
read_unlock(&em_tree->lock);
ASSERT(em && em->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().
*/
map = em->map_lookup;
num_items = 3 + map->num_stripes;
free_extent_map(em);
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)
{
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)) {
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(&block_group->lock);
if (block_group->reserved || block_group->pinned ||
block_group->used || 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);
up_write(&space_info->groups_sem);
goto next;
}
spin_unlock(&block_group->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);
}
spin_unlock(&fs_info->unused_bgs_lock);
mutex_unlock(&fs_info->reclaim_bgs_lock);
return;
flip_async:
btrfs_end_transaction(trans);
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);
}
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 unmounting the filesystem */
if (btrfs_fs_closing(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:
btrfs_put_block_group(bg);
spin_lock(&fs_info->unused_bgs_lock);
}
spin_unlock(&fs_info->unused_bgs_lock);
mutex_unlock(&fs_info->reclaim_bgs_lock);
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 extent_map_tree *em_tree;
struct extent_map *em;
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];
em_tree = &fs_info->mapping_tree;
read_lock(&em_tree->lock);
em = lookup_extent_mapping(em_tree, key->objectid, key->offset);
read_unlock(&em_tree->lock);
if (!em) {
btrfs_err(fs_info,
"logical %llu len %llu found bg but no related chunk",
key->objectid, key->offset);
return -ENOENT;
}
if (em->start != key->objectid || em->len != key->offset) {
btrfs_err(fs_info,
"block group %llu len %llu mismatch with chunk %llu len %llu",
key->objectid, key->offset, em->start, em->len);
ret = -EUCLEAN;
goto out_free_em;
}
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 != (em->map_lookup->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 & em->map_lookup->type));
ret = -EUCLEAN;
}
out_free_em:
free_extent_map(em);
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 extent_map *em;
struct map_lookup *map;
u64 *buf;
u64 bytenr;
u64 data_stripe_length;
u64 io_stripe_size;
int i, nr = 0;
int ret = 0;
em = btrfs_get_chunk_map(fs_info, chunk_start, 1);
if (IS_ERR(em))
return -EIO;
map = em->map_lookup;
data_stripe_length = em->orig_block_len;
io_stripe_size = BTRFS_STRIPE_LEN;
chunk_start = em->start;
/* For RAID5/6 adjust to a full IO stripe length */
if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK)
io_stripe_size = nr_data_stripes(map) << BTRFS_STRIPE_LEN_SHIFT;
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:
free_extent_map(em);
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 = btrfs_add_excluded_extent(fs_info, cache->start,
stripe_len);
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) {
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 = btrfs_add_excluded_extent(fs_info, logical[nr],
len);
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)
{
struct extent_map_tree *map_tree = &fs_info->mapping_tree;
struct extent_map *em;
struct btrfs_block_group *bg;
u64 start = 0;
int ret = 0;
while (1) {
read_lock(&map_tree->lock);
/*
* lookup_extent_mapping will return the first extent map
* intersecting the range, so setting @len to 1 is enough to
* get the first chunk.
*/
em = lookup_extent_mapping(map_tree, start, 1);
read_unlock(&map_tree->lock);
if (!em)
break;
bg = btrfs_lookup_block_group(fs_info, em->start);
if (!bg) {
btrfs_err(fs_info,
"chunk start=%llu len=%llu doesn't have corresponding block group",
em->start, em->len);
ret = -EUCLEAN;
free_extent_map(em);
break;
}
if (bg->start != em->start || bg->length != em->len ||
(bg->flags & BTRFS_BLOCK_GROUP_TYPE_MASK) !=
(em->map_lookup->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",
em->start, em->len,
em->map_lookup->type & BTRFS_BLOCK_GROUP_TYPE_MASK,
bg->start, bg->length,
bg->flags & BTRFS_BLOCK_GROUP_TYPE_MASK);
ret = -EUCLEAN;
free_extent_map(em);
btrfs_put_block_group(bg);
break;
}
start = em->start + em->len;
free_extent_map(em);
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;
add_new_free_space(cache, cache->start,
cache->start + cache->length);
btrfs_free_excluded_extents(cache);
}
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 extent_map_tree *em_tree = &fs_info->mapping_tree;
struct rb_node *node;
int ret = 0;
for (node = rb_first_cached(&em_tree->map); node; node = rb_next(node)) {
struct extent_map *em;
struct map_lookup *map;
struct btrfs_block_group *bg;
em = rb_entry(node, struct extent_map, rb_node);
map = em->map_lookup;
bg = btrfs_create_block_group_cache(fs_info, em->start);
if (!bg) {
ret = -ENOMEM;
break;
}
/* Fill dummy cache as FULL */
bg->length = em->len;
bg->flags = map->type;
bg->cached = BTRFS_CACHE_FINISHED;
bg->used = em->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(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 extent_map *em;
struct map_lookup *map;
u64 dev_offset;
u64 stripe_size;
int i;
int ret = 0;
em = btrfs_get_chunk_map(fs_info, chunk_offset, chunk_size);
if (IS_ERR(em))
return PTR_ERR(em);
map = em->map_lookup;
stripe_size = em->orig_block_len;
/*
* 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,
stripe_size);
if (ret)
break;
}
mutex_unlock(&fs_info->fs_devices->device_list_mutex);
free_extent_map(em);
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_delayed_refs_rsv_release(fs_info, 1);
list_del_init(&block_group->bg_list);
}
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);
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);
}
add_new_free_space(cache, chunk_offset, chunk_offset + size);
btrfs_free_excluded_extents(cache);
/*
* 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);
trans->delayed_ref_updates++;
btrfs_update_delayed_refs_rsv(trans);
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 alloction 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(leaf);
fail:
btrfs_release_path(path);
/* We didn't update the block group item, need to revert @commit_used. */
if (ret < 0) {
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 btrfs_root *root = fs_info->tree_root;
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, root, 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_delayed_refs_rsv_release(fs_info, 1);
/*
* 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,
(unsigned long) -1);
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_delayed_refs_rsv_release(fs_info, 1);
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_block_group *cache = NULL;
u64 total = num_bytes;
u64 old_val;
u64 byte_in_group;
int factor;
int ret = 0;
/* 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);
while (total) {
struct btrfs_space_info *space_info;
bool reclaim = false;
cache = btrfs_lookup_block_group(info, bytenr);
if (!cache) {
ret = -ENOENT;
break;
}
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);
byte_in_group = bytenr - cache->start;
WARN_ON(byte_in_group > cache->length);
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;
num_bytes = min(total, cache->length - byte_in_group);
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_dirty(&trans->transaction->pinned_extents,
bytenr, bytenr + num_bytes - 1,
GFP_NOFS | __GFP_NOFAIL);
}
spin_lock(&trans->transaction->dirty_bgs_lock);
if (list_empty(&cache->dirty_list)) {
list_add_tail(&cache->dirty_list,
&trans->transaction->dirty_bgs);
trans->delayed_ref_updates++;
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);
total -= num_bytes;
bytenr += num_bytes;
}
/* Modified block groups are accounted for in the delayed_refs_rsv. */
btrfs_update_delayed_refs_rsv(trans);
return ret;
}
/*
* 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) {
/*
* 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;
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;
struct extent_map_tree *em_tree;
struct extent_map *em;
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) {
em_tree = &fs_info->mapping_tree;
write_lock(&em_tree->lock);
em = lookup_extent_mapping(em_tree, block_group->start,
1);
BUG_ON(!em); /* logic error, can't happen */
remove_extent_mapping(em_tree, em);
write_unlock(&em_tree->lock);
/* once for us and once for the tree */
free_extent_map(em);
free_extent_map(em);
/*
* 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;
}
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