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- // SPDX-License-Identifier: GPL-2.0
- #include "misc.h"
- #include "ctree.h"
- #include "block-rsv.h"
- #include "space-info.h"
- #include "transaction.h"
- #include "block-group.h"
- /*
- * HOW DO BLOCK RESERVES WORK
- *
- * Think of block_rsv's as buckets for logically grouped metadata
- * reservations. Each block_rsv has a ->size and a ->reserved. ->size is
- * how large we want our block rsv to be, ->reserved is how much space is
- * currently reserved for this block reserve.
- *
- * ->failfast exists for the truncate case, and is described below.
- *
- * NORMAL OPERATION
- *
- * -> Reserve
- * Entrance: btrfs_block_rsv_add, btrfs_block_rsv_refill
- *
- * We call into btrfs_reserve_metadata_bytes() with our bytes, which is
- * accounted for in space_info->bytes_may_use, and then add the bytes to
- * ->reserved, and ->size in the case of btrfs_block_rsv_add.
- *
- * ->size is an over-estimation of how much we may use for a particular
- * operation.
- *
- * -> Use
- * Entrance: btrfs_use_block_rsv
- *
- * When we do a btrfs_alloc_tree_block() we call into btrfs_use_block_rsv()
- * to determine the appropriate block_rsv to use, and then verify that
- * ->reserved has enough space for our tree block allocation. Once
- * successful we subtract fs_info->nodesize from ->reserved.
- *
- * -> Finish
- * Entrance: btrfs_block_rsv_release
- *
- * We are finished with our operation, subtract our individual reservation
- * from ->size, and then subtract ->size from ->reserved and free up the
- * excess if there is any.
- *
- * There is some logic here to refill the delayed refs rsv or the global rsv
- * as needed, otherwise the excess is subtracted from
- * space_info->bytes_may_use.
- *
- * TYPES OF BLOCK RESERVES
- *
- * BLOCK_RSV_TRANS, BLOCK_RSV_DELOPS, BLOCK_RSV_CHUNK
- * These behave normally, as described above, just within the confines of the
- * lifetime of their particular operation (transaction for the whole trans
- * handle lifetime, for example).
- *
- * BLOCK_RSV_GLOBAL
- * It is impossible to properly account for all the space that may be required
- * to make our extent tree updates. This block reserve acts as an overflow
- * buffer in case our delayed refs reserve does not reserve enough space to
- * update the extent tree.
- *
- * We can steal from this in some cases as well, notably on evict() or
- * truncate() in order to help users recover from ENOSPC conditions.
- *
- * BLOCK_RSV_DELALLOC
- * The individual item sizes are determined by the per-inode size
- * calculations, which are described with the delalloc code. This is pretty
- * straightforward, it's just the calculation of ->size encodes a lot of
- * different items, and thus it gets used when updating inodes, inserting file
- * extents, and inserting checksums.
- *
- * BLOCK_RSV_DELREFS
- * We keep a running tally of how many delayed refs we have on the system.
- * We assume each one of these delayed refs are going to use a full
- * reservation. We use the transaction items and pre-reserve space for every
- * operation, and use this reservation to refill any gap between ->size and
- * ->reserved that may exist.
- *
- * From there it's straightforward, removing a delayed ref means we remove its
- * count from ->size and free up reservations as necessary. Since this is
- * the most dynamic block reserve in the system, we will try to refill this
- * block reserve first with any excess returned by any other block reserve.
- *
- * BLOCK_RSV_EMPTY
- * This is the fallback block reserve to make us try to reserve space if we
- * don't have a specific bucket for this allocation. It is mostly used for
- * updating the device tree and such, since that is a separate pool we're
- * content to just reserve space from the space_info on demand.
- *
- * BLOCK_RSV_TEMP
- * This is used by things like truncate and iput. We will temporarily
- * allocate a block reserve, set it to some size, and then truncate bytes
- * until we have no space left. With ->failfast set we'll simply return
- * ENOSPC from btrfs_use_block_rsv() to signal that we need to unwind and try
- * to make a new reservation. This is because these operations are
- * unbounded, so we want to do as much work as we can, and then back off and
- * re-reserve.
- */
- static u64 block_rsv_release_bytes(struct btrfs_fs_info *fs_info,
- struct btrfs_block_rsv *block_rsv,
- struct btrfs_block_rsv *dest, u64 num_bytes,
- u64 *qgroup_to_release_ret)
- {
- struct btrfs_space_info *space_info = block_rsv->space_info;
- u64 qgroup_to_release = 0;
- u64 ret;
- spin_lock(&block_rsv->lock);
- if (num_bytes == (u64)-1) {
- num_bytes = block_rsv->size;
- qgroup_to_release = block_rsv->qgroup_rsv_size;
- }
- block_rsv->size -= num_bytes;
- if (block_rsv->reserved >= block_rsv->size) {
- num_bytes = block_rsv->reserved - block_rsv->size;
- block_rsv->reserved = block_rsv->size;
- block_rsv->full = 1;
- } else {
- num_bytes = 0;
- }
- if (block_rsv->qgroup_rsv_reserved >= block_rsv->qgroup_rsv_size) {
- qgroup_to_release = block_rsv->qgroup_rsv_reserved -
- block_rsv->qgroup_rsv_size;
- block_rsv->qgroup_rsv_reserved = block_rsv->qgroup_rsv_size;
- } else {
- qgroup_to_release = 0;
- }
- spin_unlock(&block_rsv->lock);
- ret = num_bytes;
- if (num_bytes > 0) {
- if (dest) {
- spin_lock(&dest->lock);
- if (!dest->full) {
- u64 bytes_to_add;
- bytes_to_add = dest->size - dest->reserved;
- bytes_to_add = min(num_bytes, bytes_to_add);
- dest->reserved += bytes_to_add;
- if (dest->reserved >= dest->size)
- dest->full = 1;
- num_bytes -= bytes_to_add;
- }
- spin_unlock(&dest->lock);
- }
- if (num_bytes)
- btrfs_space_info_free_bytes_may_use(fs_info,
- space_info,
- num_bytes);
- }
- if (qgroup_to_release_ret)
- *qgroup_to_release_ret = qgroup_to_release;
- return ret;
- }
- int btrfs_block_rsv_migrate(struct btrfs_block_rsv *src,
- struct btrfs_block_rsv *dst, u64 num_bytes,
- bool update_size)
- {
- int ret;
- ret = btrfs_block_rsv_use_bytes(src, num_bytes);
- if (ret)
- return ret;
- btrfs_block_rsv_add_bytes(dst, num_bytes, update_size);
- return 0;
- }
- void btrfs_init_block_rsv(struct btrfs_block_rsv *rsv, unsigned short type)
- {
- memset(rsv, 0, sizeof(*rsv));
- spin_lock_init(&rsv->lock);
- rsv->type = type;
- }
- void btrfs_init_metadata_block_rsv(struct btrfs_fs_info *fs_info,
- struct btrfs_block_rsv *rsv,
- unsigned short type)
- {
- btrfs_init_block_rsv(rsv, type);
- rsv->space_info = btrfs_find_space_info(fs_info,
- BTRFS_BLOCK_GROUP_METADATA);
- }
- struct btrfs_block_rsv *btrfs_alloc_block_rsv(struct btrfs_fs_info *fs_info,
- unsigned short type)
- {
- struct btrfs_block_rsv *block_rsv;
- block_rsv = kmalloc(sizeof(*block_rsv), GFP_NOFS);
- if (!block_rsv)
- return NULL;
- btrfs_init_metadata_block_rsv(fs_info, block_rsv, type);
- return block_rsv;
- }
- void btrfs_free_block_rsv(struct btrfs_fs_info *fs_info,
- struct btrfs_block_rsv *rsv)
- {
- if (!rsv)
- return;
- btrfs_block_rsv_release(fs_info, rsv, (u64)-1, NULL);
- kfree(rsv);
- }
- int btrfs_block_rsv_add(struct btrfs_root *root,
- struct btrfs_block_rsv *block_rsv, u64 num_bytes,
- enum btrfs_reserve_flush_enum flush)
- {
- int ret;
- if (num_bytes == 0)
- return 0;
- ret = btrfs_reserve_metadata_bytes(root, block_rsv, num_bytes, flush);
- if (!ret)
- btrfs_block_rsv_add_bytes(block_rsv, num_bytes, true);
- return ret;
- }
- int btrfs_block_rsv_check(struct btrfs_block_rsv *block_rsv, int min_factor)
- {
- u64 num_bytes = 0;
- int ret = -ENOSPC;
- if (!block_rsv)
- return 0;
- spin_lock(&block_rsv->lock);
- num_bytes = div_factor(block_rsv->size, min_factor);
- if (block_rsv->reserved >= num_bytes)
- ret = 0;
- spin_unlock(&block_rsv->lock);
- return ret;
- }
- int btrfs_block_rsv_refill(struct btrfs_root *root,
- struct btrfs_block_rsv *block_rsv, u64 min_reserved,
- enum btrfs_reserve_flush_enum flush)
- {
- u64 num_bytes = 0;
- int ret = -ENOSPC;
- if (!block_rsv)
- return 0;
- spin_lock(&block_rsv->lock);
- num_bytes = min_reserved;
- if (block_rsv->reserved >= num_bytes)
- ret = 0;
- else
- num_bytes -= block_rsv->reserved;
- spin_unlock(&block_rsv->lock);
- if (!ret)
- return 0;
- ret = btrfs_reserve_metadata_bytes(root, block_rsv, num_bytes, flush);
- if (!ret) {
- btrfs_block_rsv_add_bytes(block_rsv, num_bytes, false);
- return 0;
- }
- return ret;
- }
- u64 btrfs_block_rsv_release(struct btrfs_fs_info *fs_info,
- struct btrfs_block_rsv *block_rsv, u64 num_bytes,
- u64 *qgroup_to_release)
- {
- struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
- struct btrfs_block_rsv *delayed_rsv = &fs_info->delayed_refs_rsv;
- struct btrfs_block_rsv *target = NULL;
- /*
- * If we are the delayed_rsv then push to the global rsv, otherwise dump
- * into the delayed rsv if it is not full.
- */
- if (block_rsv == delayed_rsv)
- target = global_rsv;
- else if (block_rsv != global_rsv && !delayed_rsv->full)
- target = delayed_rsv;
- if (target && block_rsv->space_info != target->space_info)
- target = NULL;
- return block_rsv_release_bytes(fs_info, block_rsv, target, num_bytes,
- qgroup_to_release);
- }
- int btrfs_block_rsv_use_bytes(struct btrfs_block_rsv *block_rsv, u64 num_bytes)
- {
- int ret = -ENOSPC;
- spin_lock(&block_rsv->lock);
- if (block_rsv->reserved >= num_bytes) {
- block_rsv->reserved -= num_bytes;
- if (block_rsv->reserved < block_rsv->size)
- block_rsv->full = 0;
- ret = 0;
- }
- spin_unlock(&block_rsv->lock);
- return ret;
- }
- void btrfs_block_rsv_add_bytes(struct btrfs_block_rsv *block_rsv,
- u64 num_bytes, bool update_size)
- {
- spin_lock(&block_rsv->lock);
- block_rsv->reserved += num_bytes;
- if (update_size)
- block_rsv->size += num_bytes;
- else if (block_rsv->reserved >= block_rsv->size)
- block_rsv->full = 1;
- spin_unlock(&block_rsv->lock);
- }
- int btrfs_cond_migrate_bytes(struct btrfs_fs_info *fs_info,
- struct btrfs_block_rsv *dest, u64 num_bytes,
- int min_factor)
- {
- struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
- u64 min_bytes;
- if (global_rsv->space_info != dest->space_info)
- return -ENOSPC;
- spin_lock(&global_rsv->lock);
- min_bytes = div_factor(global_rsv->size, min_factor);
- if (global_rsv->reserved < min_bytes + num_bytes) {
- spin_unlock(&global_rsv->lock);
- return -ENOSPC;
- }
- global_rsv->reserved -= num_bytes;
- if (global_rsv->reserved < global_rsv->size)
- global_rsv->full = 0;
- spin_unlock(&global_rsv->lock);
- btrfs_block_rsv_add_bytes(dest, num_bytes, true);
- return 0;
- }
- void btrfs_update_global_block_rsv(struct btrfs_fs_info *fs_info)
- {
- struct btrfs_block_rsv *block_rsv = &fs_info->global_block_rsv;
- struct btrfs_space_info *sinfo = block_rsv->space_info;
- u64 num_bytes;
- unsigned min_items;
- /*
- * The global block rsv is based on the size of the extent tree, the
- * checksum tree and the root tree. If the fs is empty we want to set
- * it to a minimal amount for safety.
- */
- num_bytes = btrfs_root_used(&fs_info->extent_root->root_item) +
- btrfs_root_used(&fs_info->csum_root->root_item) +
- btrfs_root_used(&fs_info->tree_root->root_item);
- /*
- * We at a minimum are going to modify the csum root, the tree root, and
- * the extent root.
- */
- min_items = 3;
- /*
- * But we also want to reserve enough space so we can do the fallback
- * global reserve for an unlink, which is an additional 5 items (see the
- * comment in __unlink_start_trans for what we're modifying.)
- *
- * But we also need space for the delayed ref updates from the unlink,
- * so its 10, 5 for the actual operation, and 5 for the delayed ref
- * updates.
- */
- min_items += 10;
- num_bytes = max_t(u64, num_bytes,
- btrfs_calc_insert_metadata_size(fs_info, min_items));
- spin_lock(&sinfo->lock);
- spin_lock(&block_rsv->lock);
- block_rsv->size = min_t(u64, num_bytes, SZ_512M);
- if (block_rsv->reserved < block_rsv->size) {
- num_bytes = block_rsv->size - block_rsv->reserved;
- btrfs_space_info_update_bytes_may_use(fs_info, sinfo,
- num_bytes);
- block_rsv->reserved = block_rsv->size;
- } else if (block_rsv->reserved > block_rsv->size) {
- num_bytes = block_rsv->reserved - block_rsv->size;
- btrfs_space_info_update_bytes_may_use(fs_info, sinfo,
- -num_bytes);
- block_rsv->reserved = block_rsv->size;
- btrfs_try_granting_tickets(fs_info, sinfo);
- }
- if (block_rsv->reserved == block_rsv->size)
- block_rsv->full = 1;
- else
- block_rsv->full = 0;
- if (block_rsv->size >= sinfo->total_bytes)
- sinfo->force_alloc = CHUNK_ALLOC_FORCE;
- spin_unlock(&block_rsv->lock);
- spin_unlock(&sinfo->lock);
- }
- void btrfs_init_global_block_rsv(struct btrfs_fs_info *fs_info)
- {
- struct btrfs_space_info *space_info;
- space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_SYSTEM);
- fs_info->chunk_block_rsv.space_info = space_info;
- space_info = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
- fs_info->global_block_rsv.space_info = space_info;
- fs_info->trans_block_rsv.space_info = space_info;
- fs_info->empty_block_rsv.space_info = space_info;
- fs_info->delayed_block_rsv.space_info = space_info;
- fs_info->delayed_refs_rsv.space_info = space_info;
- fs_info->extent_root->block_rsv = &fs_info->delayed_refs_rsv;
- fs_info->csum_root->block_rsv = &fs_info->delayed_refs_rsv;
- fs_info->dev_root->block_rsv = &fs_info->global_block_rsv;
- fs_info->tree_root->block_rsv = &fs_info->global_block_rsv;
- if (fs_info->quota_root)
- fs_info->quota_root->block_rsv = &fs_info->global_block_rsv;
- fs_info->chunk_root->block_rsv = &fs_info->chunk_block_rsv;
- btrfs_update_global_block_rsv(fs_info);
- }
- void btrfs_release_global_block_rsv(struct btrfs_fs_info *fs_info)
- {
- btrfs_block_rsv_release(fs_info, &fs_info->global_block_rsv, (u64)-1,
- NULL);
- WARN_ON(fs_info->trans_block_rsv.size > 0);
- WARN_ON(fs_info->trans_block_rsv.reserved > 0);
- WARN_ON(fs_info->chunk_block_rsv.size > 0);
- WARN_ON(fs_info->chunk_block_rsv.reserved > 0);
- WARN_ON(fs_info->delayed_block_rsv.size > 0);
- WARN_ON(fs_info->delayed_block_rsv.reserved > 0);
- WARN_ON(fs_info->delayed_refs_rsv.reserved > 0);
- WARN_ON(fs_info->delayed_refs_rsv.size > 0);
- }
- static struct btrfs_block_rsv *get_block_rsv(
- const struct btrfs_trans_handle *trans,
- const struct btrfs_root *root)
- {
- struct btrfs_fs_info *fs_info = root->fs_info;
- struct btrfs_block_rsv *block_rsv = NULL;
- if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state) ||
- (root == fs_info->csum_root && trans->adding_csums) ||
- (root == fs_info->uuid_root))
- block_rsv = trans->block_rsv;
- if (!block_rsv)
- block_rsv = root->block_rsv;
- if (!block_rsv)
- block_rsv = &fs_info->empty_block_rsv;
- return block_rsv;
- }
- struct btrfs_block_rsv *btrfs_use_block_rsv(struct btrfs_trans_handle *trans,
- struct btrfs_root *root,
- u32 blocksize)
- {
- struct btrfs_fs_info *fs_info = root->fs_info;
- struct btrfs_block_rsv *block_rsv;
- struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
- int ret;
- bool global_updated = false;
- block_rsv = get_block_rsv(trans, root);
- if (unlikely(block_rsv->size == 0))
- goto try_reserve;
- again:
- ret = btrfs_block_rsv_use_bytes(block_rsv, blocksize);
- if (!ret)
- return block_rsv;
- if (block_rsv->failfast)
- return ERR_PTR(ret);
- if (block_rsv->type == BTRFS_BLOCK_RSV_GLOBAL && !global_updated) {
- global_updated = true;
- btrfs_update_global_block_rsv(fs_info);
- goto again;
- }
- /*
- * The global reserve still exists to save us from ourselves, so don't
- * warn_on if we are short on our delayed refs reserve.
- */
- if (block_rsv->type != BTRFS_BLOCK_RSV_DELREFS &&
- btrfs_test_opt(fs_info, ENOSPC_DEBUG)) {
- static DEFINE_RATELIMIT_STATE(_rs,
- DEFAULT_RATELIMIT_INTERVAL * 10,
- /*DEFAULT_RATELIMIT_BURST*/ 1);
- if (__ratelimit(&_rs))
- WARN(1, KERN_DEBUG
- "BTRFS: block rsv %d returned %d\n",
- block_rsv->type, ret);
- }
- try_reserve:
- ret = btrfs_reserve_metadata_bytes(root, block_rsv, blocksize,
- BTRFS_RESERVE_NO_FLUSH);
- if (!ret)
- return block_rsv;
- /*
- * If we couldn't reserve metadata bytes try and use some from
- * the global reserve if its space type is the same as the global
- * reservation.
- */
- if (block_rsv->type != BTRFS_BLOCK_RSV_GLOBAL &&
- block_rsv->space_info == global_rsv->space_info) {
- ret = btrfs_block_rsv_use_bytes(global_rsv, blocksize);
- if (!ret)
- return global_rsv;
- }
- return ERR_PTR(ret);
- }
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