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1/* SPDX-License-Identifier: GPL-2.0 */2#ifndef _BCACHEFS_JOURNAL_H3#define _BCACHEFS_JOURNAL_H4 5/*6 * THE JOURNAL:7 *8 * The primary purpose of the journal is to log updates (insertions) to the9 * b-tree, to avoid having to do synchronous updates to the b-tree on disk.10 *11 * Without the journal, the b-tree is always internally consistent on12 * disk - and in fact, in the earliest incarnations bcache didn't have a journal13 * but did handle unclean shutdowns by doing all index updates synchronously14 * (with coalescing).15 *16 * Updates to interior nodes still happen synchronously and without the journal17 * (for simplicity) - this may change eventually but updates to interior nodes18 * are rare enough it's not a huge priority.19 *20 * This means the journal is relatively separate from the b-tree; it consists of21 * just a list of keys and journal replay consists of just redoing those22 * insertions in same order that they appear in the journal.23 *24 * PERSISTENCE:25 *26 * For synchronous updates (where we're waiting on the index update to hit27 * disk), the journal entry will be written out immediately (or as soon as28 * possible, if the write for the previous journal entry was still in flight).29 *30 * Synchronous updates are specified by passing a closure (@flush_cl) to31 * bch2_btree_insert() or bch_btree_insert_node(), which then pass that parameter32 * down to the journalling code. That closure will wait on the journal write to33 * complete (via closure_wait()).34 *35 * If the index update wasn't synchronous, the journal entry will be36 * written out after 10 ms have elapsed, by default (the delay_ms field37 * in struct journal).38 *39 * JOURNAL ENTRIES:40 *41 * A journal entry is variable size (struct jset), it's got a fixed length42 * header and then a variable number of struct jset_entry entries.43 *44 * Journal entries are identified by monotonically increasing 64 bit sequence45 * numbers - jset->seq; other places in the code refer to this sequence number.46 *47 * A jset_entry entry contains one or more bkeys (which is what gets inserted48 * into the b-tree). We need a container to indicate which b-tree the key is49 * for; also, the roots of the various b-trees are stored in jset_entry entries50 * (one for each b-tree) - this lets us add new b-tree types without changing51 * the on disk format.52 *53 * We also keep some things in the journal header that are logically part of the54 * superblock - all the things that are frequently updated. This is for future55 * bcache on raw flash support; the superblock (which will become another56 * journal) can't be moved or wear leveled, so it contains just enough57 * information to find the main journal, and the superblock only has to be58 * rewritten when we want to move/wear level the main journal.59 *60 * JOURNAL LAYOUT ON DISK:61 *62 * The journal is written to a ringbuffer of buckets (which is kept in the63 * superblock); the individual buckets are not necessarily contiguous on disk64 * which means that journal entries are not allowed to span buckets, but also65 * that we can resize the journal at runtime if desired (unimplemented).66 *67 * The journal buckets exist in the same pool as all the other buckets that are68 * managed by the allocator and garbage collection - garbage collection marks69 * the journal buckets as metadata buckets.70 *71 * OPEN/DIRTY JOURNAL ENTRIES:72 *73 * Open/dirty journal entries are journal entries that contain b-tree updates74 * that have not yet been written out to the b-tree on disk. We have to track75 * which journal entries are dirty, and we also have to avoid wrapping around76 * the journal and overwriting old but still dirty journal entries with new77 * journal entries.78 *79 * On disk, this is represented with the "last_seq" field of struct jset;80 * last_seq is the first sequence number that journal replay has to replay.81 *82 * To avoid overwriting dirty journal entries on disk, we keep a mapping (in83 * journal_device->seq) of for each journal bucket, the highest sequence number84 * any journal entry it contains. Then, by comparing that against last_seq we85 * can determine whether that journal bucket contains dirty journal entries or86 * not.87 *88 * To track which journal entries are dirty, we maintain a fifo of refcounts89 * (where each entry corresponds to a specific sequence number) - when a ref90 * goes to 0, that journal entry is no longer dirty.91 *92 * Journalling of index updates is done at the same time as the b-tree itself is93 * being modified (see btree_insert_key()); when we add the key to the journal94 * the pending b-tree write takes a ref on the journal entry the key was added95 * to. If a pending b-tree write would need to take refs on multiple dirty96 * journal entries, it only keeps the ref on the oldest one (since a newer97 * journal entry will still be replayed if an older entry was dirty).98 *99 * JOURNAL FILLING UP:100 *101 * There are two ways the journal could fill up; either we could run out of102 * space to write to, or we could have too many open journal entries and run out103 * of room in the fifo of refcounts. Since those refcounts are decremented104 * without any locking we can't safely resize that fifo, so we handle it the105 * same way.106 *107 * If the journal fills up, we start flushing dirty btree nodes until we can108 * allocate space for a journal write again - preferentially flushing btree109 * nodes that are pinning the oldest journal entries first.110 */111 112#include <linux/hash.h>113 114#include "journal_types.h"115 116struct bch_fs;117 118static inline void journal_wake(struct journal *j)119{120 wake_up(&j->wait);121 closure_wake_up(&j->async_wait);122}123 124static inline struct journal_buf *journal_cur_buf(struct journal *j)125{126 return j->buf + j->reservations.idx;127}128 129/* Sequence number of oldest dirty journal entry */130 131static inline u64 journal_last_seq(struct journal *j)132{133 return j->pin.front;134}135 136static inline u64 journal_cur_seq(struct journal *j)137{138 return atomic64_read(&j->seq);139}140 141static inline u64 journal_last_unwritten_seq(struct journal *j)142{143 return j->seq_ondisk + 1;144}145 146static inline int journal_state_count(union journal_res_state s, int idx)147{148 switch (idx) {149 case 0: return s.buf0_count;150 case 1: return s.buf1_count;151 case 2: return s.buf2_count;152 case 3: return s.buf3_count;153 }154 BUG();155}156 157static inline void journal_state_inc(union journal_res_state *s)158{159 s->buf0_count += s->idx == 0;160 s->buf1_count += s->idx == 1;161 s->buf2_count += s->idx == 2;162 s->buf3_count += s->idx == 3;163}164 165/*166 * Amount of space that will be taken up by some keys in the journal (i.e.167 * including the jset header)168 */169static inline unsigned jset_u64s(unsigned u64s)170{171 return u64s + sizeof(struct jset_entry) / sizeof(u64);172}173 174static inline int journal_entry_overhead(struct journal *j)175{176 return sizeof(struct jset) / sizeof(u64) + j->entry_u64s_reserved;177}178 179static inline struct jset_entry *180bch2_journal_add_entry_noreservation(struct journal_buf *buf, size_t u64s)181{182 struct jset *jset = buf->data;183 struct jset_entry *entry = vstruct_idx(jset, le32_to_cpu(jset->u64s));184 185 memset(entry, 0, sizeof(*entry));186 entry->u64s = cpu_to_le16(u64s);187 188 le32_add_cpu(&jset->u64s, jset_u64s(u64s));189 190 return entry;191}192 193static inline struct jset_entry *194journal_res_entry(struct journal *j, struct journal_res *res)195{196 return vstruct_idx(j->buf[res->idx].data, res->offset);197}198 199static inline unsigned journal_entry_init(struct jset_entry *entry, unsigned type,200 enum btree_id id, unsigned level,201 unsigned u64s)202{203 entry->u64s = cpu_to_le16(u64s);204 entry->btree_id = id;205 entry->level = level;206 entry->type = type;207 entry->pad[0] = 0;208 entry->pad[1] = 0;209 entry->pad[2] = 0;210 return jset_u64s(u64s);211}212 213static inline unsigned journal_entry_set(struct jset_entry *entry, unsigned type,214 enum btree_id id, unsigned level,215 const void *data, unsigned u64s)216{217 unsigned ret = journal_entry_init(entry, type, id, level, u64s);218 219 memcpy_u64s_small(entry->_data, data, u64s);220 return ret;221}222 223static inline struct jset_entry *224bch2_journal_add_entry(struct journal *j, struct journal_res *res,225 unsigned type, enum btree_id id,226 unsigned level, unsigned u64s)227{228 struct jset_entry *entry = journal_res_entry(j, res);229 unsigned actual = journal_entry_init(entry, type, id, level, u64s);230 231 EBUG_ON(!res->ref);232 EBUG_ON(actual > res->u64s);233 234 res->offset += actual;235 res->u64s -= actual;236 return entry;237}238 239static inline bool journal_entry_empty(struct jset *j)240{241 if (j->seq != j->last_seq)242 return false;243 244 vstruct_for_each(j, i)245 if (i->type == BCH_JSET_ENTRY_btree_keys && i->u64s)246 return false;247 return true;248}249 250/*251 * Drop reference on a buffer index and return true if the count has hit zero.252 */253static inline union journal_res_state journal_state_buf_put(struct journal *j, unsigned idx)254{255 union journal_res_state s;256 257 s.v = atomic64_sub_return(((union journal_res_state) {258 .buf0_count = idx == 0,259 .buf1_count = idx == 1,260 .buf2_count = idx == 2,261 .buf3_count = idx == 3,262 }).v, &j->reservations.counter);263 return s;264}265 266bool bch2_journal_entry_close(struct journal *);267void bch2_journal_do_writes(struct journal *);268void bch2_journal_buf_put_final(struct journal *, u64);269 270static inline void __bch2_journal_buf_put(struct journal *j, unsigned idx, u64 seq)271{272 union journal_res_state s;273 274 s = journal_state_buf_put(j, idx);275 if (!journal_state_count(s, idx))276 bch2_journal_buf_put_final(j, seq);277}278 279static inline void bch2_journal_buf_put(struct journal *j, unsigned idx, u64 seq)280{281 union journal_res_state s;282 283 s = journal_state_buf_put(j, idx);284 if (!journal_state_count(s, idx)) {285 spin_lock(&j->lock);286 bch2_journal_buf_put_final(j, seq);287 spin_unlock(&j->lock);288 }289}290 291/*292 * This function releases the journal write structure so other threads can293 * then proceed to add their keys as well.294 */295static inline void bch2_journal_res_put(struct journal *j,296 struct journal_res *res)297{298 if (!res->ref)299 return;300 301 lock_release(&j->res_map, _THIS_IP_);302 303 while (res->u64s)304 bch2_journal_add_entry(j, res,305 BCH_JSET_ENTRY_btree_keys,306 0, 0, 0);307 308 bch2_journal_buf_put(j, res->idx, res->seq);309 310 res->ref = 0;311}312 313int bch2_journal_res_get_slowpath(struct journal *, struct journal_res *,314 unsigned);315 316/* First bits for BCH_WATERMARK: */317enum journal_res_flags {318 __JOURNAL_RES_GET_NONBLOCK = BCH_WATERMARK_BITS,319 __JOURNAL_RES_GET_CHECK,320};321 322#define JOURNAL_RES_GET_NONBLOCK (1 << __JOURNAL_RES_GET_NONBLOCK)323#define JOURNAL_RES_GET_CHECK (1 << __JOURNAL_RES_GET_CHECK)324 325static inline int journal_res_get_fast(struct journal *j,326 struct journal_res *res,327 unsigned flags)328{329 union journal_res_state old, new;330 331 old.v = atomic64_read(&j->reservations.counter);332 do {333 new.v = old.v;334 335 /*336 * Check if there is still room in the current journal337 * entry:338 */339 if (new.cur_entry_offset + res->u64s > j->cur_entry_u64s)340 return 0;341 342 EBUG_ON(!journal_state_count(new, new.idx));343 344 if ((flags & BCH_WATERMARK_MASK) < j->watermark)345 return 0;346 347 new.cur_entry_offset += res->u64s;348 journal_state_inc(&new);349 350 /*351 * If the refcount would overflow, we have to wait:352 * XXX - tracepoint this:353 */354 if (!journal_state_count(new, new.idx))355 return 0;356 357 if (flags & JOURNAL_RES_GET_CHECK)358 return 1;359 } while (!atomic64_try_cmpxchg(&j->reservations.counter,360 &old.v, new.v));361 362 res->ref = true;363 res->idx = old.idx;364 res->offset = old.cur_entry_offset;365 res->seq = le64_to_cpu(j->buf[old.idx].data->seq);366 return 1;367}368 369static inline int bch2_journal_res_get(struct journal *j, struct journal_res *res,370 unsigned u64s, unsigned flags)371{372 int ret;373 374 EBUG_ON(res->ref);375 EBUG_ON(!test_bit(JOURNAL_running, &j->flags));376 377 res->u64s = u64s;378 379 if (journal_res_get_fast(j, res, flags))380 goto out;381 382 ret = bch2_journal_res_get_slowpath(j, res, flags);383 if (ret)384 return ret;385out:386 if (!(flags & JOURNAL_RES_GET_CHECK)) {387 lock_acquire_shared(&j->res_map, 0,388 (flags & JOURNAL_RES_GET_NONBLOCK) != 0,389 NULL, _THIS_IP_);390 EBUG_ON(!res->ref);391 }392 return 0;393}394 395/* journal_entry_res: */396 397void bch2_journal_entry_res_resize(struct journal *,398 struct journal_entry_res *,399 unsigned);400 401int bch2_journal_flush_seq_async(struct journal *, u64, struct closure *);402void bch2_journal_flush_async(struct journal *, struct closure *);403 404int bch2_journal_flush_seq(struct journal *, u64, unsigned);405int bch2_journal_flush(struct journal *);406bool bch2_journal_noflush_seq(struct journal *, u64);407int bch2_journal_meta(struct journal *);408 409void bch2_journal_halt(struct journal *);410 411static inline int bch2_journal_error(struct journal *j)412{413 return j->reservations.cur_entry_offset == JOURNAL_ENTRY_ERROR_VAL414 ? -EIO : 0;415}416 417struct bch_dev;418 419static inline void bch2_journal_set_replay_done(struct journal *j)420{421 BUG_ON(!test_bit(JOURNAL_running, &j->flags));422 set_bit(JOURNAL_replay_done, &j->flags);423}424 425void bch2_journal_unblock(struct journal *);426void bch2_journal_block(struct journal *);427struct journal_buf *bch2_next_write_buffer_flush_journal_buf(struct journal *j, u64 max_seq);428 429void __bch2_journal_debug_to_text(struct printbuf *, struct journal *);430void bch2_journal_debug_to_text(struct printbuf *, struct journal *);431void bch2_journal_pins_to_text(struct printbuf *, struct journal *);432bool bch2_journal_seq_pins_to_text(struct printbuf *, struct journal *, u64 *);433 434int bch2_set_nr_journal_buckets(struct bch_fs *, struct bch_dev *,435 unsigned nr);436int bch2_dev_journal_alloc(struct bch_dev *, bool);437int bch2_fs_journal_alloc(struct bch_fs *);438 439void bch2_dev_journal_stop(struct journal *, struct bch_dev *);440 441void bch2_fs_journal_stop(struct journal *);442int bch2_fs_journal_start(struct journal *, u64);443 444void bch2_dev_journal_exit(struct bch_dev *);445int bch2_dev_journal_init(struct bch_dev *, struct bch_sb *);446void bch2_fs_journal_exit(struct journal *);447int bch2_fs_journal_init(struct journal *);448 449#endif /* _BCACHEFS_JOURNAL_H */450