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Diffstat (limited to 'fs/bcachefs/journal.h')
| -rw-r--r-- | fs/bcachefs/journal.h | 450 |
1 files changed, 450 insertions, 0 deletions
diff --git a/fs/bcachefs/journal.h b/fs/bcachefs/journal.h new file mode 100644 index 0000000000..2f768e11ae --- /dev/null +++ b/fs/bcachefs/journal.h @@ -0,0 +1,450 @@ +/* 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; +} + +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 *); + +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 */ |