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linux/fs/bcachefs/journal_reclaim.h
Kent Overstreet 09caeabe1a 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>
2024-01-01 11:47:41 -05:00

82 lines
2.3 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _BCACHEFS_JOURNAL_RECLAIM_H
#define _BCACHEFS_JOURNAL_RECLAIM_H
#define JOURNAL_PIN (32 * 1024)
static inline void journal_reclaim_kick(struct journal *j)
{
struct task_struct *p = READ_ONCE(j->reclaim_thread);
j->reclaim_kicked = true;
if (p)
wake_up_process(p);
}
unsigned bch2_journal_dev_buckets_available(struct journal *,
struct journal_device *,
enum journal_space_from);
void bch2_journal_set_watermark(struct journal *);
void bch2_journal_space_available(struct journal *);
static inline bool journal_pin_active(struct journal_entry_pin *pin)
{
return pin->seq != 0;
}
static inline struct journal_entry_pin_list *
journal_seq_pin(struct journal *j, u64 seq)
{
EBUG_ON(seq < j->pin.front || seq >= j->pin.back);
return &j->pin.data[seq & j->pin.mask];
}
void bch2_journal_reclaim_fast(struct journal *);
bool __bch2_journal_pin_put(struct journal *, u64);
void bch2_journal_pin_put(struct journal *, u64);
void bch2_journal_pin_drop(struct journal *, struct journal_entry_pin *);
void bch2_journal_pin_set(struct journal *, u64, struct journal_entry_pin *,
journal_pin_flush_fn);
static inline void bch2_journal_pin_add(struct journal *j, u64 seq,
struct journal_entry_pin *pin,
journal_pin_flush_fn flush_fn)
{
if (unlikely(!journal_pin_active(pin) || pin->seq > seq))
bch2_journal_pin_set(j, seq, pin, flush_fn);
}
void bch2_journal_pin_copy(struct journal *,
struct journal_entry_pin *,
struct journal_entry_pin *,
journal_pin_flush_fn);
static inline void bch2_journal_pin_update(struct journal *j, u64 seq,
struct journal_entry_pin *pin,
journal_pin_flush_fn flush_fn)
{
if (unlikely(!journal_pin_active(pin) || pin->seq < seq))
bch2_journal_pin_set(j, seq, pin, flush_fn);
}
void bch2_journal_pin_flush(struct journal *, struct journal_entry_pin *);
void bch2_journal_do_discards(struct journal *);
int bch2_journal_reclaim(struct journal *);
void bch2_journal_reclaim_stop(struct journal *);
int bch2_journal_reclaim_start(struct journal *);
bool bch2_journal_flush_pins(struct journal *, u64);
static inline bool bch2_journal_flush_all_pins(struct journal *j)
{
return bch2_journal_flush_pins(j, U64_MAX);
}
int bch2_journal_flush_device_pins(struct journal *, int);
#endif /* _BCACHEFS_JOURNAL_RECLAIM_H */