+++ /dev/null
-/* 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);
-}
-
-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)
-{
- 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;
-}
-
-bool bch2_journal_entry_close(struct journal *);
-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 *);
-struct journal_buf *bch2_next_write_buffer_flush_journal_buf(struct journal *j, u64 max_seq);
-
-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 */
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