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linux/fs/bcachefs/btree_write_buffer.h

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bcachefs: Btree write buffer This adds a new method of doing btree updates - a straight write buffer, implemented as a flat fixed size array. This is only useful when we don't need to read from the btree in order to do the update, and when reading is infrequent - perfect for the LRU btree. This will make LRU btree updates fast enough that we'll be able to use it for persistently indexing buckets by fragmentation, which will be a massive boost to copygc performance. Changes: - A new btree_insert_type enum, for btree_insert_entries. Specifies btree, btree key cache, or btree write buffer. - bch2_trans_update_buffered(): updates via the btree write buffer don't need a btree path, so we need a new update path. - Transaction commit path changes: The update to the btree write buffer both mutates global, and can fail if there isn't currently room. Therefore we do all write buffer updates in the transaction all at once, and also if it fails we have to revert filesystem usage counter changes. If there isn't room we flush the write buffer in the transaction commit error path and retry. - A new persistent option, for specifying the number of entries in the write buffer. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-01-03 22:00:50 -07:00
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _BCACHEFS_BTREE_WRITE_BUFFER_H
#define _BCACHEFS_BTREE_WRITE_BUFFER_H
bcachefs: btree write buffer now slurps keys from journal Previosuly, the transaction commit path would have to add keys to the btree write buffer as a separate operation, requiring additional global synchronization. This patch introduces a new journal entry type, which indicates that the keys need to be copied into the btree write buffer prior to being written out. We switch the journal entry type back to JSET_ENTRY_btree_keys prior to write, so this is not an on disk format change. Flushing the btree write buffer may require pulling keys out of journal entries yet to be written, and quiescing outstanding journal reservations; we previously added journal->buf_lock for synchronization with the journal write path. We also can't put strict bounds on the number of keys in the journal destined for the write buffer, which means we might overflow the size of the preallocated buffer and have to reallocate - this introduces a potentially fatal memory allocation failure. This is something we'll have to watch for, if it becomes an issue in practice we can do additional mitigation. The transaction commit path no longer has to explicitly check if the write buffer is full and wait on flushing; this is another performance optimization. Instead, when the btree write buffer is close to full we change the journal watermark, so that only reservations for journal reclaim are allowed. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-11-02 15:57:19 -07:00
#include "bkey.h"
bcachefs: Eytzinger accumulation for accounting keys The btree write buffer takes as input keys from the journal, sorts them, deduplicates them, and flushes them back to the btree in sorted order. The disk space accounting rewrite is moving accounting to normal btree keys, with update (in this case deltas) accumulated in the write buffer and then flushed to the btree; but this is going to increase the number of keys handled by the write buffer by perhaps as much as a factor of 3x-5x. The overhead from copying around and sorting this many keys would cause a significant performance regression, but: there is huge locality in updates to accounting keys that we can take advantage of. Instead of appending accounting keys to the list of keys to be sorted, this patch adds an eytzinger search tree of recently seen accounting keys. We look up the accounting key in the eytzinger search tree and apply the delta directly, adding it if it doesn't exist, and periodically prune the eytzinger tree of unused entries. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-12-27 09:33:21 -07:00
#include "disk_accounting.h"
bcachefs: btree write buffer now slurps keys from journal Previosuly, the transaction commit path would have to add keys to the btree write buffer as a separate operation, requiring additional global synchronization. This patch introduces a new journal entry type, which indicates that the keys need to be copied into the btree write buffer prior to being written out. We switch the journal entry type back to JSET_ENTRY_btree_keys prior to write, so this is not an on disk format change. Flushing the btree write buffer may require pulling keys out of journal entries yet to be written, and quiescing outstanding journal reservations; we previously added journal->buf_lock for synchronization with the journal write path. We also can't put strict bounds on the number of keys in the journal destined for the write buffer, which means we might overflow the size of the preallocated buffer and have to reallocate - this introduces a potentially fatal memory allocation failure. This is something we'll have to watch for, if it becomes an issue in practice we can do additional mitigation. The transaction commit path no longer has to explicitly check if the write buffer is full and wait on flushing; this is another performance optimization. Instead, when the btree write buffer is close to full we change the journal watermark, so that only reservations for journal reclaim are allowed. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-11-02 15:57:19 -07:00
static inline bool bch2_btree_write_buffer_should_flush(struct bch_fs *c)
{
struct btree_write_buffer *wb = &c->btree_write_buffer;
return wb->inc.keys.nr + wb->flushing.keys.nr > wb->inc.keys.size / 4;
}
static inline bool bch2_btree_write_buffer_must_wait(struct bch_fs *c)
{
struct btree_write_buffer *wb = &c->btree_write_buffer;
return wb->inc.keys.nr > wb->inc.keys.size * 3 / 4;
}
struct btree_trans;
bcachefs: Btree write buffer This adds a new method of doing btree updates - a straight write buffer, implemented as a flat fixed size array. This is only useful when we don't need to read from the btree in order to do the update, and when reading is infrequent - perfect for the LRU btree. This will make LRU btree updates fast enough that we'll be able to use it for persistently indexing buckets by fragmentation, which will be a massive boost to copygc performance. Changes: - A new btree_insert_type enum, for btree_insert_entries. Specifies btree, btree key cache, or btree write buffer. - bch2_trans_update_buffered(): updates via the btree write buffer don't need a btree path, so we need a new update path. - Transaction commit path changes: The update to the btree write buffer both mutates global, and can fail if there isn't currently room. Therefore we do all write buffer updates in the transaction all at once, and also if it fails we have to revert filesystem usage counter changes. If there isn't room we flush the write buffer in the transaction commit error path and retry. - A new persistent option, for specifying the number of entries in the write buffer. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-01-03 22:00:50 -07:00
int bch2_btree_write_buffer_flush_sync(struct btree_trans *);
bcachefs: btree write buffer now slurps keys from journal Previosuly, the transaction commit path would have to add keys to the btree write buffer as a separate operation, requiring additional global synchronization. This patch introduces a new journal entry type, which indicates that the keys need to be copied into the btree write buffer prior to being written out. We switch the journal entry type back to JSET_ENTRY_btree_keys prior to write, so this is not an on disk format change. Flushing the btree write buffer may require pulling keys out of journal entries yet to be written, and quiescing outstanding journal reservations; we previously added journal->buf_lock for synchronization with the journal write path. We also can't put strict bounds on the number of keys in the journal destined for the write buffer, which means we might overflow the size of the preallocated buffer and have to reallocate - this introduces a potentially fatal memory allocation failure. This is something we'll have to watch for, if it becomes an issue in practice we can do additional mitigation. The transaction commit path no longer has to explicitly check if the write buffer is full and wait on flushing; this is another performance optimization. Instead, when the btree write buffer is close to full we change the journal watermark, so that only reservations for journal reclaim are allowed. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-11-02 15:57:19 -07:00
int bch2_btree_write_buffer_flush_nocheck_rw(struct btree_trans *);
bcachefs: bch2_btree_write_buffer_flush() -> bch2_btree_write_buffer_tryflush() More accurate naming. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-11-02 17:36:00 -07:00
int bch2_btree_write_buffer_tryflush(struct btree_trans *);
bcachefs: Btree write buffer This adds a new method of doing btree updates - a straight write buffer, implemented as a flat fixed size array. This is only useful when we don't need to read from the btree in order to do the update, and when reading is infrequent - perfect for the LRU btree. This will make LRU btree updates fast enough that we'll be able to use it for persistently indexing buckets by fragmentation, which will be a massive boost to copygc performance. Changes: - A new btree_insert_type enum, for btree_insert_entries. Specifies btree, btree key cache, or btree write buffer. - bch2_trans_update_buffered(): updates via the btree write buffer don't need a btree path, so we need a new update path. - Transaction commit path changes: The update to the btree write buffer both mutates global, and can fail if there isn't currently room. Therefore we do all write buffer updates in the transaction all at once, and also if it fails we have to revert filesystem usage counter changes. If there isn't room we flush the write buffer in the transaction commit error path and retry. - A new persistent option, for specifying the number of entries in the write buffer. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-01-03 22:00:50 -07:00
bcachefs: bch2_btree_write_buffer_maybe_flush() Add a new helper for checking references to write buffer btrees, where we need a flush before we definitively know we have an inconsistency. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2024-06-29 15:32:01 -07:00
struct bkey_buf;
int bch2_btree_write_buffer_maybe_flush(struct btree_trans *, struct bkey_s_c, struct bkey_buf *);
bcachefs: btree write buffer now slurps keys from journal Previosuly, the transaction commit path would have to add keys to the btree write buffer as a separate operation, requiring additional global synchronization. This patch introduces a new journal entry type, which indicates that the keys need to be copied into the btree write buffer prior to being written out. We switch the journal entry type back to JSET_ENTRY_btree_keys prior to write, so this is not an on disk format change. Flushing the btree write buffer may require pulling keys out of journal entries yet to be written, and quiescing outstanding journal reservations; we previously added journal->buf_lock for synchronization with the journal write path. We also can't put strict bounds on the number of keys in the journal destined for the write buffer, which means we might overflow the size of the preallocated buffer and have to reallocate - this introduces a potentially fatal memory allocation failure. This is something we'll have to watch for, if it becomes an issue in practice we can do additional mitigation. The transaction commit path no longer has to explicitly check if the write buffer is full and wait on flushing; this is another performance optimization. Instead, when the btree write buffer is close to full we change the journal watermark, so that only reservations for journal reclaim are allowed. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-11-02 15:57:19 -07:00
struct journal_keys_to_wb {
struct btree_write_buffer_keys *wb;
size_t room;
u64 seq;
};
bcachefs: Eytzinger accumulation for accounting keys The btree write buffer takes as input keys from the journal, sorts them, deduplicates them, and flushes them back to the btree in sorted order. The disk space accounting rewrite is moving accounting to normal btree keys, with update (in this case deltas) accumulated in the write buffer and then flushed to the btree; but this is going to increase the number of keys handled by the write buffer by perhaps as much as a factor of 3x-5x. The overhead from copying around and sorting this many keys would cause a significant performance regression, but: there is huge locality in updates to accounting keys that we can take advantage of. Instead of appending accounting keys to the list of keys to be sorted, this patch adds an eytzinger search tree of recently seen accounting keys. We look up the accounting key in the eytzinger search tree and apply the delta directly, adding it if it doesn't exist, and periodically prune the eytzinger tree of unused entries. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-12-27 09:33:21 -07:00
static inline int wb_key_cmp(const void *_l, const void *_r)
{
const struct btree_write_buffered_key *l = _l;
const struct btree_write_buffered_key *r = _r;
return cmp_int(l->btree, r->btree) ?: bpos_cmp(l->k.k.p, r->k.k.p);
}
int bch2_accounting_key_to_wb_slowpath(struct bch_fs *,
enum btree_id, struct bkey_i_accounting *);
static inline int bch2_accounting_key_to_wb(struct bch_fs *c,
enum btree_id btree, struct bkey_i_accounting *k)
{
struct btree_write_buffer *wb = &c->btree_write_buffer;
struct btree_write_buffered_key search;
search.btree = btree;
search.k.k.p = k->k.p;
unsigned idx = eytzinger0_find(wb->accounting.data, wb->accounting.nr,
sizeof(wb->accounting.data[0]),
wb_key_cmp, &search);
if (idx >= wb->accounting.nr)
return bch2_accounting_key_to_wb_slowpath(c, btree, k);
struct bkey_i_accounting *dst = bkey_i_to_accounting(&wb->accounting.data[idx].k);
bch2_accounting_accumulate(dst, accounting_i_to_s_c(k));
return 0;
}
bcachefs: __bch2_journal_key_to_wb -> bch2_journal_key_to_wb_slowpath Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-12-27 18:26:30 -07:00
int bch2_journal_key_to_wb_slowpath(struct bch_fs *,
bcachefs: btree write buffer now slurps keys from journal Previosuly, the transaction commit path would have to add keys to the btree write buffer as a separate operation, requiring additional global synchronization. This patch introduces a new journal entry type, which indicates that the keys need to be copied into the btree write buffer prior to being written out. We switch the journal entry type back to JSET_ENTRY_btree_keys prior to write, so this is not an on disk format change. Flushing the btree write buffer may require pulling keys out of journal entries yet to be written, and quiescing outstanding journal reservations; we previously added journal->buf_lock for synchronization with the journal write path. We also can't put strict bounds on the number of keys in the journal destined for the write buffer, which means we might overflow the size of the preallocated buffer and have to reallocate - this introduces a potentially fatal memory allocation failure. This is something we'll have to watch for, if it becomes an issue in practice we can do additional mitigation. The transaction commit path no longer has to explicitly check if the write buffer is full and wait on flushing; this is another performance optimization. Instead, when the btree write buffer is close to full we change the journal watermark, so that only reservations for journal reclaim are allowed. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-11-02 15:57:19 -07:00
struct journal_keys_to_wb *,
enum btree_id, struct bkey_i *);
bcachefs: Eytzinger accumulation for accounting keys The btree write buffer takes as input keys from the journal, sorts them, deduplicates them, and flushes them back to the btree in sorted order. The disk space accounting rewrite is moving accounting to normal btree keys, with update (in this case deltas) accumulated in the write buffer and then flushed to the btree; but this is going to increase the number of keys handled by the write buffer by perhaps as much as a factor of 3x-5x. The overhead from copying around and sorting this many keys would cause a significant performance regression, but: there is huge locality in updates to accounting keys that we can take advantage of. Instead of appending accounting keys to the list of keys to be sorted, this patch adds an eytzinger search tree of recently seen accounting keys. We look up the accounting key in the eytzinger search tree and apply the delta directly, adding it if it doesn't exist, and periodically prune the eytzinger tree of unused entries. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-12-27 09:33:21 -07:00
static inline int __bch2_journal_key_to_wb(struct bch_fs *c,
bcachefs: btree write buffer now slurps keys from journal Previosuly, the transaction commit path would have to add keys to the btree write buffer as a separate operation, requiring additional global synchronization. This patch introduces a new journal entry type, which indicates that the keys need to be copied into the btree write buffer prior to being written out. We switch the journal entry type back to JSET_ENTRY_btree_keys prior to write, so this is not an on disk format change. Flushing the btree write buffer may require pulling keys out of journal entries yet to be written, and quiescing outstanding journal reservations; we previously added journal->buf_lock for synchronization with the journal write path. We also can't put strict bounds on the number of keys in the journal destined for the write buffer, which means we might overflow the size of the preallocated buffer and have to reallocate - this introduces a potentially fatal memory allocation failure. This is something we'll have to watch for, if it becomes an issue in practice we can do additional mitigation. The transaction commit path no longer has to explicitly check if the write buffer is full and wait on flushing; this is another performance optimization. Instead, when the btree write buffer is close to full we change the journal watermark, so that only reservations for journal reclaim are allowed. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-11-02 15:57:19 -07:00
struct journal_keys_to_wb *dst,
enum btree_id btree, struct bkey_i *k)
{
if (unlikely(!dst->room))
bcachefs: __bch2_journal_key_to_wb -> bch2_journal_key_to_wb_slowpath Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-12-27 18:26:30 -07:00
return bch2_journal_key_to_wb_slowpath(c, dst, btree, k);
bcachefs: btree write buffer now slurps keys from journal Previosuly, the transaction commit path would have to add keys to the btree write buffer as a separate operation, requiring additional global synchronization. This patch introduces a new journal entry type, which indicates that the keys need to be copied into the btree write buffer prior to being written out. We switch the journal entry type back to JSET_ENTRY_btree_keys prior to write, so this is not an on disk format change. Flushing the btree write buffer may require pulling keys out of journal entries yet to be written, and quiescing outstanding journal reservations; we previously added journal->buf_lock for synchronization with the journal write path. We also can't put strict bounds on the number of keys in the journal destined for the write buffer, which means we might overflow the size of the preallocated buffer and have to reallocate - this introduces a potentially fatal memory allocation failure. This is something we'll have to watch for, if it becomes an issue in practice we can do additional mitigation. The transaction commit path no longer has to explicitly check if the write buffer is full and wait on flushing; this is another performance optimization. Instead, when the btree write buffer is close to full we change the journal watermark, so that only reservations for journal reclaim are allowed. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-11-02 15:57:19 -07:00
struct btree_write_buffered_key *wb_k = &darray_top(dst->wb->keys);
wb_k->journal_seq = dst->seq;
wb_k->btree = btree;
bkey_copy(&wb_k->k, k);
dst->wb->keys.nr++;
dst->room--;
return 0;
}
bcachefs: Eytzinger accumulation for accounting keys The btree write buffer takes as input keys from the journal, sorts them, deduplicates them, and flushes them back to the btree in sorted order. The disk space accounting rewrite is moving accounting to normal btree keys, with update (in this case deltas) accumulated in the write buffer and then flushed to the btree; but this is going to increase the number of keys handled by the write buffer by perhaps as much as a factor of 3x-5x. The overhead from copying around and sorting this many keys would cause a significant performance regression, but: there is huge locality in updates to accounting keys that we can take advantage of. Instead of appending accounting keys to the list of keys to be sorted, this patch adds an eytzinger search tree of recently seen accounting keys. We look up the accounting key in the eytzinger search tree and apply the delta directly, adding it if it doesn't exist, and periodically prune the eytzinger tree of unused entries. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-12-27 09:33:21 -07:00
static inline int bch2_journal_key_to_wb(struct bch_fs *c,
struct journal_keys_to_wb *dst,
enum btree_id btree, struct bkey_i *k)
{
EBUG_ON(!dst->seq);
return k->k.type == KEY_TYPE_accounting
? bch2_accounting_key_to_wb(c, btree, bkey_i_to_accounting(k))
: __bch2_journal_key_to_wb(c, dst, btree, k);
}
bcachefs: btree write buffer now slurps keys from journal Previosuly, the transaction commit path would have to add keys to the btree write buffer as a separate operation, requiring additional global synchronization. This patch introduces a new journal entry type, which indicates that the keys need to be copied into the btree write buffer prior to being written out. We switch the journal entry type back to JSET_ENTRY_btree_keys prior to write, so this is not an on disk format change. Flushing the btree write buffer may require pulling keys out of journal entries yet to be written, and quiescing outstanding journal reservations; we previously added journal->buf_lock for synchronization with the journal write path. We also can't put strict bounds on the number of keys in the journal destined for the write buffer, which means we might overflow the size of the preallocated buffer and have to reallocate - this introduces a potentially fatal memory allocation failure. This is something we'll have to watch for, if it becomes an issue in practice we can do additional mitigation. The transaction commit path no longer has to explicitly check if the write buffer is full and wait on flushing; this is another performance optimization. Instead, when the btree write buffer is close to full we change the journal watermark, so that only reservations for journal reclaim are allowed. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-11-02 15:57:19 -07:00
void bch2_journal_keys_to_write_buffer_start(struct bch_fs *, struct journal_keys_to_wb *, u64);
bcachefs: Eytzinger accumulation for accounting keys The btree write buffer takes as input keys from the journal, sorts them, deduplicates them, and flushes them back to the btree in sorted order. The disk space accounting rewrite is moving accounting to normal btree keys, with update (in this case deltas) accumulated in the write buffer and then flushed to the btree; but this is going to increase the number of keys handled by the write buffer by perhaps as much as a factor of 3x-5x. The overhead from copying around and sorting this many keys would cause a significant performance regression, but: there is huge locality in updates to accounting keys that we can take advantage of. Instead of appending accounting keys to the list of keys to be sorted, this patch adds an eytzinger search tree of recently seen accounting keys. We look up the accounting key in the eytzinger search tree and apply the delta directly, adding it if it doesn't exist, and periodically prune the eytzinger tree of unused entries. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-12-27 09:33:21 -07:00
int bch2_journal_keys_to_write_buffer_end(struct bch_fs *, struct journal_keys_to_wb *);
bcachefs: Btree write buffer This adds a new method of doing btree updates - a straight write buffer, implemented as a flat fixed size array. This is only useful when we don't need to read from the btree in order to do the update, and when reading is infrequent - perfect for the LRU btree. This will make LRU btree updates fast enough that we'll be able to use it for persistently indexing buckets by fragmentation, which will be a massive boost to copygc performance. Changes: - A new btree_insert_type enum, for btree_insert_entries. Specifies btree, btree key cache, or btree write buffer. - bch2_trans_update_buffered(): updates via the btree write buffer don't need a btree path, so we need a new update path. - Transaction commit path changes: The update to the btree write buffer both mutates global, and can fail if there isn't currently room. Therefore we do all write buffer updates in the transaction all at once, and also if it fails we have to revert filesystem usage counter changes. If there isn't room we flush the write buffer in the transaction commit error path and retry. - A new persistent option, for specifying the number of entries in the write buffer. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-01-03 22:00:50 -07:00
bcachefs: btree write buffer now slurps keys from journal Previosuly, the transaction commit path would have to add keys to the btree write buffer as a separate operation, requiring additional global synchronization. This patch introduces a new journal entry type, which indicates that the keys need to be copied into the btree write buffer prior to being written out. We switch the journal entry type back to JSET_ENTRY_btree_keys prior to write, so this is not an on disk format change. Flushing the btree write buffer may require pulling keys out of journal entries yet to be written, and quiescing outstanding journal reservations; we previously added journal->buf_lock for synchronization with the journal write path. We also can't put strict bounds on the number of keys in the journal destined for the write buffer, which means we might overflow the size of the preallocated buffer and have to reallocate - this introduces a potentially fatal memory allocation failure. This is something we'll have to watch for, if it becomes an issue in practice we can do additional mitigation. The transaction commit path no longer has to explicitly check if the write buffer is full and wait on flushing; this is another performance optimization. Instead, when the btree write buffer is close to full we change the journal watermark, so that only reservations for journal reclaim are allowed. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-11-02 15:57:19 -07:00
int bch2_btree_write_buffer_resize(struct bch_fs *, size_t);
bcachefs: Btree write buffer This adds a new method of doing btree updates - a straight write buffer, implemented as a flat fixed size array. This is only useful when we don't need to read from the btree in order to do the update, and when reading is infrequent - perfect for the LRU btree. This will make LRU btree updates fast enough that we'll be able to use it for persistently indexing buckets by fragmentation, which will be a massive boost to copygc performance. Changes: - A new btree_insert_type enum, for btree_insert_entries. Specifies btree, btree key cache, or btree write buffer. - bch2_trans_update_buffered(): updates via the btree write buffer don't need a btree path, so we need a new update path. - Transaction commit path changes: The update to the btree write buffer both mutates global, and can fail if there isn't currently room. Therefore we do all write buffer updates in the transaction all at once, and also if it fails we have to revert filesystem usage counter changes. If there isn't room we flush the write buffer in the transaction commit error path and retry. - A new persistent option, for specifying the number of entries in the write buffer. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2023-01-03 22:00:50 -07:00
void bch2_fs_btree_write_buffer_exit(struct bch_fs *);
int bch2_fs_btree_write_buffer_init(struct bch_fs *);
#endif /* _BCACHEFS_BTREE_WRITE_BUFFER_H */
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