/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _BCACHEFS_JOURNAL_H
#define _BCACHEFS_JOURNAL_H
/*
* THE JOURNAL:
*
* The primary purpose of the journal is to log updates (insertions) to the
* b-tree, to avoid having to do synchronous updates to the b-tree on disk.
*
* Without the journal, the b-tree is always internally consistent on
* disk - and in fact, in the earliest incarnations bcache didn't have a journal
* but did handle unclean shutdowns by doing all index updates synchronously
* (with coalescing).
*
* Updates to interior nodes still happen synchronously and without the journal
* (for simplicity) - this may change eventually but updates to interior nodes
* are rare enough it's not a huge priority.
*
* This means the journal is relatively separate from the b-tree; it consists of
* just a list of keys and journal replay consists of just redoing those
* insertions in same order that they appear in the journal.
*
* PERSISTENCE:
*
* For synchronous updates (where we're waiting on the index update to hit
* disk), the journal entry will be written out immediately (or as soon as
* possible, if the write for the previous journal entry was still in flight).
*
* Synchronous updates are specified by passing a closure (@flush_cl) to
* bch2_btree_insert() or bch_btree_insert_node(), which then pass that parameter
* down to the journalling code. That closure will wait on the journal write to
* complete (via closure_wait()).
*
* If the index update wasn't synchronous, the journal entry will be
* written out after 10 ms have elapsed, by default (the delay_ms field
* in struct journal).
*
* JOURNAL ENTRIES:
*
* A journal entry is variable size (struct jset), it's got a fixed length
* header and then a variable number of struct jset_entry entries.
*
* Journal entries are identified by monotonically increasing 64 bit sequence
* numbers - jset->seq; other places in the code refer to this sequence number.
*
* A jset_entry entry contains one or more bkeys (which is what gets inserted
* into the b-tree). We need a container to indicate which b-tree the key is
* for; also, the roots of the various b-trees are stored in jset_entry entries
* (one for each b-tree) - this lets us add new b-tree types without changing
* the on disk format.
*
* We also keep some things in the journal header that are logically part of the
* superblock - all the things that are frequently updated. This is for future
* bcache on raw flash support; the superblock (which will become another
* journal) can't be moved or wear leveled, so it contains just enough
* information to find the main journal, and the superblock only has to be
* rewritten when we want to move/wear level the main journal.
*
* JOURNAL LAYOUT ON DISK:
*
* The journal is written to a ringbuffer of buckets (which is kept in the
* superblock); the individual buckets are not necessarily contiguous on disk
* which means that journal entries are not allowed to span buckets, but also
* that we can resize the journal at runtime if desired (unimplemented).
*
* The journal buckets exist in the same pool as all the other buckets that are
* managed by the allocator and garbage collection - garbage collection marks
* the journal buckets as metadata buckets.
*
* OPEN/DIRTY JOURNAL ENTRIES:
*
* Open/dirty journal entries are journal entries that contain b-tree updates
* that have not yet been written out to the b-tree on disk. We have to track
* which journal entries are dirty, and we also have to avoid wrapping around
* the journal and overwriting old but still dirty journal entries with new
* journal entries.
*
* On disk, this is represented with the "last_seq" field of struct jset;
* last_seq is the first sequence number that journal replay has to replay.
*
* To avoid overwriting dirty journal entries on disk, we keep a mapping (in
* journal_device->seq) of for each journal bucket, the highest sequence number
* any journal entry it contains. Then, by comparing that against last_seq we
* can determine whether that journal bucket contains dirty journal entries or
* not.
*
* To track which journal entries are dirty, we maintain a fifo of refcounts
* (where each entry corresponds to a specific sequence number) - when a ref
* goes to 0, that journal entry is no longer dirty.
*
* Journalling of index updates is done at the same time as the b-tree itself is
* being modified (see btree_insert_key()); when we add the key to the journal
* the pending b-tree write takes a ref on the journal entry the key was added
* to. If a pending b-tree write would need to take refs on multiple dirty
* journal entries, it only keeps the ref on the oldest one (since a newer
* journal entry will still be replayed if an older entry was dirty).
*
* JOURNAL FILLING UP:
*
* There are two ways the journal could fill up; either we could run out of
* space to write to, or we could have too many open journal entries and run out
* of room in the fifo of refcounts. Since those refcounts are decremented
* without any locking we can't safely resize that fifo, so we handle it the
* same way.
*
* If the journal fills up, we start flushing dirty btree nodes until we can
* allocate space for a journal write again - preferentially flushing btree
* nodes that are pinning the oldest journal entries first.
*/
#include <linux/hash.h>
#include "journal_types.h"
struct bch_fs;
static inline void journal_wake(struct journal *j)
{
wake_up(&j->wait);
closure_wake_up(&j->async_wait);
closure_wake_up(&j->preres_wait);
}
static inline struct journal_buf *journal_cur_buf(struct journal *j)
{
return j->buf + j->reservations.idx;
}
/* Sequence number of oldest dirty journal entry */
static inline u64 journal_last_seq(struct journal *j)
{
return j->pin.front;
}
static inline u64 journal_cur_seq(struct journal *j)
{
return atomic64_read(&j->seq);
}
static inline u64 journal_last_unwritten_seq(struct journal *j)
{
return j->seq_ondisk + 1;
}
static inline int journal_state_count(union journal_res_state s, int idx)
{
switch (idx) {
case 0: return s.buf0_count;
case 1: return s.buf1_count;
case 2: return s.buf2_count;
case 3: return s.buf3_count;
}
BUG();
}
static inline void journal_state_inc(union journal_res_state *s)
{
s->buf0_count += s->idx == 0;
s->buf1_count += s->idx == 1;
s->buf2_count += s->idx == 2;
s->buf3_count += s->idx == 3;
}
/*
* Amount of space that will be taken up by some keys in the journal (i.e.
* including the jset header)
*/
static inline unsigned jset_u64s(unsigned u64s)
{
return u64s + sizeof(struct jset_entry) / sizeof(u64);
}
static inline int journal_entry_overhead(struct journal *j)
{
return sizeof(struct jset) / sizeof(u64) + j->entry_u64s_reserved;
}
static inline struct jset_entry *
bch2_journal_add_entry_noreservation(struct journal_buf *buf, size_t u64s)
{
struct jset *jset = buf->data;
struct jset_entry *entry = vstruct_idx(jset, le32_to_cpu(jset->u64s));
memset(entry, 0, sizeof(*entry));
entry->u64s = cpu_to_le16(u64s);
le32_add_cpu(&jset->u64s, jset_u64s(u64s));
return entry;
}
static inline struct jset_entry *
journal_res_entry(struct journal *j, struct journal_res *res)
{
return vstruct_idx(j->buf[res->idx].data, res->offset);
}
static inline unsigned journal_entry_init(struct jset_entry *entry, unsigned type,
enum btree_id id, unsigned level,
unsigned u64s)
{
entry->u64s = cpu_to_le16(u64s);
entry->btree_id = id;
entry->level = level;
entry->type = type;
entry->pad[0] = 0;
entry->pad[1] = 0;
entry->pad[2] = 0;
return jset_u64s(u64s);
}
static inline unsigned journal_entry_set(struct jset_entry *entry, unsigned type,
enum btree_id id, unsigned level,
const void *data, unsigned u64s)
{
unsigned ret = journal_entry_init(entry, type, id, level, u64s);
memcpy_u64s_small(entry->_data, data, u64s);
return ret;
}
static inline struct jset_entry *
bch2_journal_add_entry(struct journal *j, struct journal_res *res,
unsigned type, enum btree_id id,
unsigned level, unsigned u64s)
{
struct jset_entry *entry = journal_res_entry(j, res);
unsigned actual = journal_entry_init(entry, type, id, level, u64s);
EBUG_ON(!res->ref);
EBUG_ON(actual > res->u64s);
res->offset += actual;
res->u64s -= actual;
return entry;
}
static inline bool journal_entry_empty(struct jset *j)
{
struct jset_entry *i;
if (j->seq != j->last_seq)
return false;
vstruct_for_each(j, i)
if (i->type == BCH_JSET_ENTRY_btree_keys && i->u64s)
return false;
return true;
}
/*
* Drop reference on a buffer index and return true if the count has hit zero.
*/
static inline union journal_res_state journal_state_buf_put(struct journal *j, unsigned idx)
{
union journal_res_state s;
s.v = atomic64_sub_return(((union journal_res_state) {
.buf0_count = idx == 0,
.buf1_count = idx == 1,
.buf2_count = idx == 2,
.buf3_count = idx == 3,
}).v, &j->reservations.counter);
return s;
}
void bch2_journal_buf_put_final(struct journal *, u64, bool);
static inline void __bch2_journal_buf_put(struct journal *j, unsigned idx, u64 seq)
{
union journal_res_state s;
s = journal_state_buf_put(j, idx);
if (!journal_state_count(s, idx))
bch2_journal_buf_put_final(j, seq, idx == s.unwritten_idx);
}
static inline void bch2_journal_buf_put(struct journal *j, unsigned idx, u64 seq)
{
union journal_res_state s;
s = journal_state_buf_put(j, idx);
if (!journal_state_count(s, idx)) {
spin_lock(&j->lock);
bch2_journal_buf_put_final(j, seq, idx == s.unwritten_idx);
spin_unlock(&j->lock);
}
}
/*
* This function releases the journal write structure so other threads can
* then proceed to add their keys as well.
*/
static inline void bch2_journal_res_put(struct journal *j,
struct journal_res *res)
{
if (!res->ref)
return;
lock_release(&j->res_map, _THIS_IP_);
while (res->u64s)
bch2_journal_add_entry(j, res,
BCH_JSET_ENTRY_btree_keys,
0, 0, 0);
bch2_journal_buf_put(j, res->idx, res->seq);
res->ref = 0;
}
int bch2_journal_res_get_slowpath(struct journal *, struct journal_res *,
unsigned);
/* First bits for BCH_WATERMARK: */
enum journal_res_flags {
__JOURNAL_RES_GET_NONBLOCK = BCH_WATERMARK_BITS,
__JOURNAL_RES_GET_CHECK,
};
#define JOURNAL_RES_GET_NONBLOCK (1 << __JOURNAL_RES_GET_NONBLOCK)
#define JOURNAL_RES_GET_CHECK (1 << __JOURNAL_RES_GET_CHECK)
static inline int journal_res_get_fast(struct journal *j,
struct journal_res *res,
unsigned flags)
{
union journal_res_state old, new;
u64 v = atomic64_read(&j->reservations.counter);
do {
old.v = new.v = v;
/*
* Check if there is still room in the current journal
* entry:
*/
if (new.cur_entry_offset + res->u64s > j->cur_entry_u64s)
return 0;
EBUG_ON(!journal_state_count(new, new.idx));
if ((flags & BCH_WATERMARK_MASK) < j->watermark)
return 0;
new.cur_entry_offset += res->u64s;
journal_state_inc(&new);
/*
* If the refcount would overflow, we have to wait:
* XXX - tracepoint this:
*/
if (!journal_state_count(new, new.idx))
return 0;
if (flags & JOURNAL_RES_GET_CHECK)
return 1;
} while ((v = atomic64_cmpxchg(&j->reservations.counter,
old.v, new.v)) != old.v);
res->ref = true;
res->idx = old.idx;
res->offset = old.cur_entry_offset;
res->seq = le64_to_cpu(j->buf[old.idx].data->seq);
return 1;
}
static inline int bch2_journal_res_get(struct journal *j, struct journal_res *res,
unsigned u64s, unsigned flags)
{
int ret;
EBUG_ON(res->ref);
EBUG_ON(!test_bit(JOURNAL_STARTED, &j->flags));
res->u64s = u64s;
if (journal_res_get_fast(j, res, flags))
goto out;
ret = bch2_journal_res_get_slowpath(j, res, flags);
if (ret)
return ret;
out:
if (!(flags & JOURNAL_RES_GET_CHECK)) {
lock_acquire_shared(&j->res_map, 0,
(flags & JOURNAL_RES_GET_NONBLOCK) != 0,
NULL, _THIS_IP_);
EBUG_ON(!res->ref);
}
return 0;
}
/* journal_entry_res: */
void bch2_journal_entry_res_resize(struct journal *,
struct journal_entry_res *,
unsigned);
int bch2_journal_flush_seq_async(struct journal *, u64, struct closure *);
void bch2_journal_flush_async(struct journal *, struct closure *);
int bch2_journal_flush_seq(struct journal *, u64);
int bch2_journal_flush(struct journal *);
bool bch2_journal_noflush_seq(struct journal *, u64);
int bch2_journal_meta(struct journal *);
void bch2_journal_halt(struct journal *);
static inline int bch2_journal_error(struct journal *j)
{
return j->reservations.cur_entry_offset == JOURNAL_ENTRY_ERROR_VAL
? -EIO : 0;
}
struct bch_dev;
static inline void bch2_journal_set_replay_done(struct journal *j)
{
BUG_ON(!test_bit(JOURNAL_STARTED, &j->flags));
set_bit(JOURNAL_REPLAY_DONE, &j->flags);
}
void bch2_journal_unblock(struct journal *);
void bch2_journal_block(struct journal *);
void __bch2_journal_debug_to_text(struct printbuf *, struct journal *);
void bch2_journal_debug_to_text(struct printbuf *, struct journal *);
void bch2_journal_pins_to_text(struct printbuf *, struct journal *);
bool bch2_journal_seq_pins_to_text(struct printbuf *, struct journal *, u64 *);
int bch2_set_nr_journal_buckets(struct bch_fs *, struct bch_dev *,
unsigned nr);
int bch2_dev_journal_alloc(struct bch_dev *);
int bch2_fs_journal_alloc(struct bch_fs *);
void bch2_dev_journal_stop(struct journal *, struct bch_dev *);
void bch2_fs_journal_stop(struct journal *);
int bch2_fs_journal_start(struct journal *, u64);
void bch2_dev_journal_exit(struct bch_dev *);
int bch2_dev_journal_init(struct bch_dev *, struct bch_sb *);
void bch2_fs_journal_exit(struct journal *);
int bch2_fs_journal_init(struct journal *);
#endif /* _BCACHEFS_JOURNAL_H */
