]> git.sesse.net Git - bcachefs-tools-debian/blobdiff - libbcachefs/btree_write_buffer.c
Move c_src dirs back to toplevel
[bcachefs-tools-debian] / libbcachefs / btree_write_buffer.c
index 026c249a3f441c9073aaa2641a9fec9290b50baf..5c1169c78dafec7bf238854a74b37120f1c835cd 100644 (file)
 #include "btree_write_buffer.h"
 #include "error.h"
 #include "journal.h"
+#include "journal_io.h"
 #include "journal_reclaim.h"
 
-#include <linux/sort.h>
+#include <linux/prefetch.h>
 
-static int btree_write_buffered_key_cmp(const void *_l, const void *_r)
+static int bch2_btree_write_buffer_journal_flush(struct journal *,
+                               struct journal_entry_pin *, u64);
+
+static int bch2_journal_keys_to_write_buffer(struct bch_fs *, struct journal_buf *);
+
+static inline bool __wb_key_ref_cmp(const struct wb_key_ref *l, const struct wb_key_ref *r)
 {
-       const struct btree_write_buffered_key *l = _l;
-       const struct btree_write_buffered_key *r = _r;
+       return (cmp_int(l->hi, r->hi) ?:
+               cmp_int(l->mi, r->mi) ?:
+               cmp_int(l->lo, r->lo)) >= 0;
+}
 
-       return  cmp_int(l->btree, r->btree) ?:
-               bpos_cmp(l->k.k.p, r->k.k.p) ?:
-               cmp_int(l->journal_seq, r->journal_seq) ?:
-               cmp_int(l->journal_offset, r->journal_offset);
+static inline bool wb_key_ref_cmp(const struct wb_key_ref *l, const struct wb_key_ref *r)
+{
+#ifdef CONFIG_X86_64
+       int cmp;
+
+       asm("mov   (%[l]), %%rax;"
+           "sub   (%[r]), %%rax;"
+           "mov  8(%[l]), %%rax;"
+           "sbb  8(%[r]), %%rax;"
+           "mov 16(%[l]), %%rax;"
+           "sbb 16(%[r]), %%rax;"
+           : "=@ccae" (cmp)
+           : [l] "r" (l), [r] "r" (r)
+           : "rax", "cc");
+
+       EBUG_ON(cmp != __wb_key_ref_cmp(l, r));
+       return cmp;
+#else
+       return __wb_key_ref_cmp(l, r);
+#endif
 }
 
-static int btree_write_buffered_journal_cmp(const void *_l, const void *_r)
+/* Compare excluding idx, the low 24 bits: */
+static inline bool wb_key_eq(const void *_l, const void *_r)
 {
-       const struct btree_write_buffered_key *l = _l;
-       const struct btree_write_buffered_key *r = _r;
+       const struct wb_key_ref *l = _l;
+       const struct wb_key_ref *r = _r;
 
-       return  cmp_int(l->journal_seq, r->journal_seq);
+       return !((l->hi ^ r->hi)|
+                (l->mi ^ r->mi)|
+                ((l->lo >> 24) ^ (r->lo >> 24)));
 }
 
-static int bch2_btree_write_buffer_flush_one(struct btree_trans *trans,
-                                            struct btree_iter *iter,
-                                            struct btree_write_buffered_key *wb,
-                                            unsigned commit_flags,
-                                            bool *write_locked,
-                                            size_t *fast)
+static noinline void wb_sort(struct wb_key_ref *base, size_t num)
+{
+       size_t n = num, a = num / 2;
+
+       if (!a)         /* num < 2 || size == 0 */
+               return;
+
+       for (;;) {
+               size_t b, c, d;
+
+               if (a)                  /* Building heap: sift down --a */
+                       --a;
+               else if (--n)           /* Sorting: Extract root to --n */
+                       swap(base[0], base[n]);
+               else                    /* Sort complete */
+                       break;
+
+               /*
+                * Sift element at "a" down into heap.  This is the
+                * "bottom-up" variant, which significantly reduces
+                * calls to cmp_func(): we find the sift-down path all
+                * the way to the leaves (one compare per level), then
+                * backtrack to find where to insert the target element.
+                *
+                * Because elements tend to sift down close to the leaves,
+                * this uses fewer compares than doing two per level
+                * on the way down.  (A bit more than half as many on
+                * average, 3/4 worst-case.)
+                */
+               for (b = a; c = 2*b + 1, (d = c + 1) < n;)
+                       b = wb_key_ref_cmp(base + c, base + d) ? c : d;
+               if (d == n)             /* Special case last leaf with no sibling */
+                       b = c;
+
+               /* Now backtrack from "b" to the correct location for "a" */
+               while (b != a && wb_key_ref_cmp(base + a, base + b))
+                       b = (b - 1) / 2;
+               c = b;                  /* Where "a" belongs */
+               while (b != a) {        /* Shift it into place */
+                       b = (b - 1) / 2;
+                       swap(base[b], base[c]);
+               }
+       }
+}
+
+static noinline int wb_flush_one_slowpath(struct btree_trans *trans,
+                                         struct btree_iter *iter,
+                                         struct btree_write_buffered_key *wb)
+{
+       struct btree_path *path = btree_iter_path(trans, iter);
+
+       bch2_btree_node_unlock_write(trans, path, path->l[0].b);
+
+       trans->journal_res.seq = wb->journal_seq;
+
+       return bch2_trans_update(trans, iter, &wb->k,
+                                BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE) ?:
+               bch2_trans_commit(trans, NULL, NULL,
+                                 BCH_TRANS_COMMIT_no_enospc|
+                                 BCH_TRANS_COMMIT_no_check_rw|
+                                 BCH_TRANS_COMMIT_no_journal_res|
+                                 BCH_TRANS_COMMIT_journal_reclaim);
+}
+
+static inline int wb_flush_one(struct btree_trans *trans, struct btree_iter *iter,
+                              struct btree_write_buffered_key *wb,
+                              bool *write_locked, size_t *fast)
 {
        struct bch_fs *c = trans->c;
        struct btree_path *path;
        int ret;
 
+       EBUG_ON(!wb->journal_seq);
+       EBUG_ON(!c->btree_write_buffer.flushing.pin.seq);
+       EBUG_ON(c->btree_write_buffer.flushing.pin.seq > wb->journal_seq);
+
        ret = bch2_btree_iter_traverse(iter);
        if (ret)
                return ret;
 
-       path = iter->path;
+       /*
+        * We can't clone a path that has write locks: unshare it now, before
+        * set_pos and traverse():
+        */
+       if (btree_iter_path(trans, iter)->ref > 1)
+               iter->path = __bch2_btree_path_make_mut(trans, iter->path, true, _THIS_IP_);
+
+       path = btree_iter_path(trans, iter);
 
        if (!*write_locked) {
                ret = bch2_btree_node_lock_write(trans, path, &path->l[0].b->c);
@@ -56,77 +155,117 @@ static int bch2_btree_write_buffer_flush_one(struct btree_trans *trans,
                *write_locked = true;
        }
 
-       if (!bch2_btree_node_insert_fits(c, path->l[0].b, wb->k.k.u64s)) {
-               bch2_btree_node_unlock_write(trans, path, path->l[0].b);
+       if (unlikely(!bch2_btree_node_insert_fits(c, path->l[0].b, wb->k.k.u64s))) {
                *write_locked = false;
-               goto trans_commit;
+               return wb_flush_one_slowpath(trans, iter, wb);
        }
 
        bch2_btree_insert_key_leaf(trans, path, &wb->k, wb->journal_seq);
        (*fast)++;
-
-       if (path->ref > 1) {
-               /*
-                * We can't clone a path that has write locks: if the path is
-                * shared, unlock before set_pos(), traverse():
-                */
-               bch2_btree_node_unlock_write(trans, path, path->l[0].b);
-               *write_locked = false;
-       }
        return 0;
-trans_commit:
-       return  bch2_trans_update(trans, iter, &wb->k, 0) ?:
-               bch2_trans_commit(trans, NULL, NULL,
-                                 commit_flags|
-                                 BTREE_INSERT_NOFAIL|
-                                 BTREE_INSERT_JOURNAL_RECLAIM);
 }
 
-static union btree_write_buffer_state btree_write_buffer_switch(struct btree_write_buffer *wb)
+/*
+ * Update a btree with a write buffered key using the journal seq of the
+ * original write buffer insert.
+ *
+ * It is not safe to rejournal the key once it has been inserted into the write
+ * buffer because that may break recovery ordering. For example, the key may
+ * have already been modified in the active write buffer in a seq that comes
+ * before the current transaction. If we were to journal this key again and
+ * crash, recovery would process updates in the wrong order.
+ */
+static int
+btree_write_buffered_insert(struct btree_trans *trans,
+                         struct btree_write_buffered_key *wb)
 {
-       union btree_write_buffer_state old, new;
-       u64 v = READ_ONCE(wb->state.v);
+       struct btree_iter iter;
+       int ret;
 
-       do {
-               old.v = new.v = v;
+       bch2_trans_iter_init(trans, &iter, wb->btree, bkey_start_pos(&wb->k.k),
+                            BTREE_ITER_CACHED|BTREE_ITER_INTENT);
+
+       trans->journal_res.seq = wb->journal_seq;
+
+       ret   = bch2_btree_iter_traverse(&iter) ?:
+               bch2_trans_update(trans, &iter, &wb->k,
+                                 BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE);
+       bch2_trans_iter_exit(trans, &iter);
+       return ret;
+}
+
+static void move_keys_from_inc_to_flushing(struct btree_write_buffer *wb)
+{
+       struct bch_fs *c = container_of(wb, struct bch_fs, btree_write_buffer);
+       struct journal *j = &c->journal;
 
-               new.nr = 0;
-               new.idx++;
-       } while ((v = atomic64_cmpxchg_acquire(&wb->state.counter, old.v, new.v)) != old.v);
+       if (!wb->inc.keys.nr)
+               return;
 
-       while (old.idx == 0 ? wb->state.ref0 : wb->state.ref1)
-               cpu_relax();
+       bch2_journal_pin_add(j, wb->inc.keys.data[0].journal_seq, &wb->flushing.pin,
+                            bch2_btree_write_buffer_journal_flush);
 
-       smp_mb();
+       darray_resize(&wb->flushing.keys, min_t(size_t, 1U << 20, wb->flushing.keys.nr + wb->inc.keys.nr));
+       darray_resize(&wb->sorted, wb->flushing.keys.size);
 
-       return old;
+       if (!wb->flushing.keys.nr && wb->sorted.size >= wb->inc.keys.nr) {
+               swap(wb->flushing.keys, wb->inc.keys);
+               goto out;
+       }
+
+       size_t nr = min(darray_room(wb->flushing.keys),
+                       wb->sorted.size - wb->flushing.keys.nr);
+       nr = min(nr, wb->inc.keys.nr);
+
+       memcpy(&darray_top(wb->flushing.keys),
+              wb->inc.keys.data,
+              sizeof(wb->inc.keys.data[0]) * nr);
+
+       memmove(wb->inc.keys.data,
+               wb->inc.keys.data + nr,
+              sizeof(wb->inc.keys.data[0]) * (wb->inc.keys.nr - nr));
+
+       wb->flushing.keys.nr    += nr;
+       wb->inc.keys.nr         -= nr;
+out:
+       if (!wb->inc.keys.nr)
+               bch2_journal_pin_drop(j, &wb->inc.pin);
+       else
+               bch2_journal_pin_update(j, wb->inc.keys.data[0].journal_seq, &wb->inc.pin,
+                                       bch2_btree_write_buffer_journal_flush);
+
+       if (j->watermark) {
+               spin_lock(&j->lock);
+               bch2_journal_set_watermark(j);
+               spin_unlock(&j->lock);
+       }
+
+       BUG_ON(wb->sorted.size < wb->flushing.keys.nr);
 }
 
-int __bch2_btree_write_buffer_flush(struct btree_trans *trans, unsigned commit_flags,
-                                   bool locked)
+static int bch2_btree_write_buffer_flush_locked(struct btree_trans *trans)
 {
        struct bch_fs *c = trans->c;
        struct journal *j = &c->journal;
        struct btree_write_buffer *wb = &c->btree_write_buffer;
-       struct journal_entry_pin pin;
-       struct btree_write_buffered_key *i, *dst, *keys;
        struct btree_iter iter = { NULL };
-       size_t nr = 0, skipped = 0, fast = 0;
+       size_t skipped = 0, fast = 0, slowpath = 0;
        bool write_locked = false;
-       union btree_write_buffer_state s;
        int ret = 0;
 
-       memset(&pin, 0, sizeof(pin));
-
-       if (!locked && !mutex_trylock(&wb->flush_lock))
-               return 0;
+       bch2_trans_unlock(trans);
+       bch2_trans_begin(trans);
 
-       bch2_journal_pin_copy(j, &pin, &wb->journal_pin, NULL);
-       bch2_journal_pin_drop(j, &wb->journal_pin);
+       mutex_lock(&wb->inc.lock);
+       move_keys_from_inc_to_flushing(wb);
+       mutex_unlock(&wb->inc.lock);
 
-       s = btree_write_buffer_switch(wb);
-       keys = wb->keys[s.idx];
-       nr = s.nr;
+       for (size_t i = 0; i < wb->flushing.keys.nr; i++) {
+               wb->sorted.data[i].idx = i;
+               wb->sorted.data[i].btree = wb->flushing.keys.data[i].btree;
+               memcpy(&wb->sorted.data[i].pos, &wb->flushing.keys.data[i].k.k.p, sizeof(struct bpos));
+       }
+       wb->sorted.nr = wb->flushing.keys.nr;
 
        /*
         * We first sort so that we can detect and skip redundant updates, and
@@ -135,205 +274,374 @@ int __bch2_btree_write_buffer_flush(struct btree_trans *trans, unsigned commit_f
         *
         * However, since we're not flushing in the order they appear in the
         * journal we won't be able to drop our journal pin until everything is
-        * flushed - which means this could deadlock the journal, if we weren't
-        * passing BTREE_INSERT_JORUNAL_RECLAIM. This causes the update to fail
+        * flushed - which means this could deadlock the journal if we weren't
+        * passing BCH_TRANS_COMMIT_journal_reclaim. This causes the update to fail
         * if it would block taking a journal reservation.
         *
-        * If that happens, we sort them by the order they appeared in the
-        * journal - after dropping redundant entries - and then restart
-        * flushing, this time dropping journal pins as we go.
+        * If that happens, simply skip the key so we can optimistically insert
+        * as many keys as possible in the fast path.
         */
+       wb_sort(wb->sorted.data, wb->sorted.nr);
+
+       darray_for_each(wb->sorted, i) {
+               struct btree_write_buffered_key *k = &wb->flushing.keys.data[i->idx];
+
+               for (struct wb_key_ref *n = i + 1; n < min(i + 4, &darray_top(wb->sorted)); n++)
+                       prefetch(&wb->flushing.keys.data[n->idx]);
 
-       sort(keys, nr, sizeof(keys[0]),
-            btree_write_buffered_key_cmp, NULL);
+               BUG_ON(!k->journal_seq);
+
+               if (i + 1 < &darray_top(wb->sorted) &&
+                   wb_key_eq(i, i + 1)) {
+                       struct btree_write_buffered_key *n = &wb->flushing.keys.data[i[1].idx];
 
-       for (i = keys; i < keys + nr; i++) {
-               if (i + 1 < keys + nr &&
-                   i[0].btree == i[1].btree &&
-                   bpos_eq(i[0].k.k.p, i[1].k.k.p)) {
                        skipped++;
+                       n->journal_seq = min_t(u64, n->journal_seq, k->journal_seq);
+                       k->journal_seq = 0;
                        continue;
                }
 
-               if (write_locked &&
-                   (iter.path->btree_id != i->btree ||
-                    bpos_gt(i->k.k.p, iter.path->l[0].b->key.k.p))) {
-                       bch2_btree_node_unlock_write(trans, iter.path, iter.path->l[0].b);
-                       write_locked = false;
+               if (write_locked) {
+                       struct btree_path *path = btree_iter_path(trans, &iter);
+
+                       if (path->btree_id != i->btree ||
+                           bpos_gt(k->k.k.p, path->l[0].b->key.k.p)) {
+                               bch2_btree_node_unlock_write(trans, path, path->l[0].b);
+                               write_locked = false;
+                       }
                }
 
-               if (!iter.path || iter.path->btree_id != i->btree) {
+               if (!iter.path || iter.btree_id != k->btree) {
                        bch2_trans_iter_exit(trans, &iter);
-                       bch2_trans_iter_init(trans, &iter, i->btree, i->k.k.p, BTREE_ITER_INTENT);
+                       bch2_trans_iter_init(trans, &iter, k->btree, k->k.k.p,
+                                            BTREE_ITER_INTENT|BTREE_ITER_ALL_SNAPSHOTS);
                }
 
-               bch2_btree_iter_set_pos(&iter, i->k.k.p);
-               iter.path->preserve = false;
+               bch2_btree_iter_set_pos(&iter, k->k.k.p);
+               btree_iter_path(trans, &iter)->preserve = false;
 
                do {
-                       ret = bch2_btree_write_buffer_flush_one(trans, &iter, i,
-                                               commit_flags, &write_locked, &fast);
+                       if (race_fault()) {
+                               ret = -BCH_ERR_journal_reclaim_would_deadlock;
+                               break;
+                       }
+
+                       ret = wb_flush_one(trans, &iter, k, &write_locked, &fast);
                        if (!write_locked)
                                bch2_trans_begin(trans);
                } while (bch2_err_matches(ret, BCH_ERR_transaction_restart));
 
-               if (ret)
+               if (!ret) {
+                       k->journal_seq = 0;
+               } else if (ret == -BCH_ERR_journal_reclaim_would_deadlock) {
+                       slowpath++;
+                       ret = 0;
+               } else
                        break;
        }
 
-       if (write_locked)
-               bch2_btree_node_unlock_write(trans, iter.path, iter.path->l[0].b);
+       if (write_locked) {
+               struct btree_path *path = btree_iter_path(trans, &iter);
+               bch2_btree_node_unlock_write(trans, path, path->l[0].b);
+       }
        bch2_trans_iter_exit(trans, &iter);
 
-       trace_write_buffer_flush(trans, nr, skipped, fast, wb->size);
-
-       if (ret == -BCH_ERR_journal_reclaim_would_deadlock)
-               goto slowpath;
+       if (ret)
+               goto err;
 
+       if (slowpath) {
+               /*
+                * Flush in the order they were present in the journal, so that
+                * we can release journal pins:
+                * The fastpath zapped the seq of keys that were successfully flushed so
+                * we can skip those here.
+                */
+               trace_and_count(c, write_buffer_flush_slowpath, trans, slowpath, wb->flushing.keys.nr);
+
+               darray_for_each(wb->flushing.keys, i) {
+                       if (!i->journal_seq)
+                               continue;
+
+                       bch2_journal_pin_update(j, i->journal_seq, &wb->flushing.pin,
+                                               bch2_btree_write_buffer_journal_flush);
+
+                       bch2_trans_begin(trans);
+
+                       ret = commit_do(trans, NULL, NULL,
+                                       BCH_WATERMARK_reclaim|
+                                       BCH_TRANS_COMMIT_no_check_rw|
+                                       BCH_TRANS_COMMIT_no_enospc|
+                                       BCH_TRANS_COMMIT_no_journal_res|
+                                       BCH_TRANS_COMMIT_journal_reclaim,
+                                       btree_write_buffered_insert(trans, i));
+                       if (ret)
+                               goto err;
+               }
+       }
+err:
        bch2_fs_fatal_err_on(ret, c, "%s: insert error %s", __func__, bch2_err_str(ret));
-out:
-       bch2_journal_pin_drop(j, &pin);
-       mutex_unlock(&wb->flush_lock);
+       trace_write_buffer_flush(trans, wb->flushing.keys.nr, skipped, fast, 0);
+       bch2_journal_pin_drop(j, &wb->flushing.pin);
+       wb->flushing.keys.nr = 0;
        return ret;
-slowpath:
-       trace_write_buffer_flush_slowpath(trans, i - keys, nr);
-
-       dst = keys;
-       for (; i < keys + nr; i++) {
-               if (i + 1 < keys + nr &&
-                   i[0].btree == i[1].btree &&
-                   bpos_eq(i[0].k.k.p, i[1].k.k.p))
-                       continue;
+}
+
+static int fetch_wb_keys_from_journal(struct bch_fs *c, u64 seq)
+{
+       struct journal *j = &c->journal;
+       struct journal_buf *buf;
+       int ret = 0;
 
-               *dst = *i;
-               dst++;
+       while (!ret && (buf = bch2_next_write_buffer_flush_journal_buf(j, seq))) {
+               ret = bch2_journal_keys_to_write_buffer(c, buf);
+               mutex_unlock(&j->buf_lock);
        }
-       nr = dst - keys;
 
-       sort(keys, nr, sizeof(keys[0]),
-            btree_write_buffered_journal_cmp,
-            NULL);
+       return ret;
+}
 
-       for (i = keys; i < keys + nr; i++) {
-               if (i->journal_seq > pin.seq) {
-                       struct journal_entry_pin pin2;
+static int btree_write_buffer_flush_seq(struct btree_trans *trans, u64 seq)
+{
+       struct bch_fs *c = trans->c;
+       struct btree_write_buffer *wb = &c->btree_write_buffer;
+       int ret = 0, fetch_from_journal_err;
 
-                       memset(&pin2, 0, sizeof(pin2));
+       do {
+               bch2_trans_unlock(trans);
 
-                       bch2_journal_pin_add(j, i->journal_seq, &pin2, NULL);
-                       bch2_journal_pin_drop(j, &pin);
-                       bch2_journal_pin_copy(j, &pin, &pin2, NULL);
-                       bch2_journal_pin_drop(j, &pin2);
-               }
+               fetch_from_journal_err = fetch_wb_keys_from_journal(c, seq);
 
-               ret = commit_do(trans, NULL, NULL,
-                               commit_flags|
-                               BTREE_INSERT_NOFAIL|
-                               BTREE_INSERT_JOURNAL_RECLAIM|
-                               JOURNAL_WATERMARK_reserved,
-                               __bch2_btree_insert(trans, i->btree, &i->k, 0));
-               if (bch2_fs_fatal_err_on(ret, c, "%s: insert error %s", __func__, bch2_err_str(ret)))
-                       break;
-       }
+               /*
+                * On memory allocation failure, bch2_btree_write_buffer_flush_locked()
+                * is not guaranteed to empty wb->inc:
+                */
+               mutex_lock(&wb->flushing.lock);
+               ret = bch2_btree_write_buffer_flush_locked(trans);
+               mutex_unlock(&wb->flushing.lock);
+       } while (!ret &&
+                (fetch_from_journal_err ||
+                 (wb->inc.pin.seq && wb->inc.pin.seq <= seq) ||
+                 (wb->flushing.pin.seq && wb->flushing.pin.seq <= seq)));
 
-       goto out;
+       return ret;
 }
 
-int bch2_btree_write_buffer_flush_sync(struct btree_trans *trans)
+static int bch2_btree_write_buffer_journal_flush(struct journal *j,
+                               struct journal_entry_pin *_pin, u64 seq)
 {
-       bch2_trans_unlock(trans);
-       mutex_lock(&trans->c->btree_write_buffer.flush_lock);
-       return __bch2_btree_write_buffer_flush(trans, 0, true);
+       struct bch_fs *c = container_of(j, struct bch_fs, journal);
+
+       return bch2_trans_run(c, btree_write_buffer_flush_seq(trans, seq));
 }
 
-int bch2_btree_write_buffer_flush(struct btree_trans *trans)
+int bch2_btree_write_buffer_flush_sync(struct btree_trans *trans)
 {
-       return __bch2_btree_write_buffer_flush(trans, 0, false);
+       struct bch_fs *c = trans->c;
+
+       trace_and_count(c, write_buffer_flush_sync, trans, _RET_IP_);
+
+       return btree_write_buffer_flush_seq(trans, journal_cur_seq(&c->journal));
 }
 
-static int bch2_btree_write_buffer_journal_flush(struct journal *j,
-                               struct journal_entry_pin *_pin, u64 seq)
+int bch2_btree_write_buffer_flush_nocheck_rw(struct btree_trans *trans)
 {
-       struct bch_fs *c = container_of(j, struct bch_fs, journal);
+       struct bch_fs *c = trans->c;
        struct btree_write_buffer *wb = &c->btree_write_buffer;
+       int ret = 0;
 
-       mutex_lock(&wb->flush_lock);
+       if (mutex_trylock(&wb->flushing.lock)) {
+               ret = bch2_btree_write_buffer_flush_locked(trans);
+               mutex_unlock(&wb->flushing.lock);
+       }
 
-       return bch2_trans_run(c,
-                       __bch2_btree_write_buffer_flush(&trans, BTREE_INSERT_NOCHECK_RW, true));
+       return ret;
 }
 
-static inline u64 btree_write_buffer_ref(int idx)
+int bch2_btree_write_buffer_tryflush(struct btree_trans *trans)
 {
-       return ((union btree_write_buffer_state) {
-               .ref0 = idx == 0,
-               .ref1 = idx == 1,
-       }).v;
+       struct bch_fs *c = trans->c;
+
+       if (!bch2_write_ref_tryget(c, BCH_WRITE_REF_btree_write_buffer))
+               return -BCH_ERR_erofs_no_writes;
+
+       int ret = bch2_btree_write_buffer_flush_nocheck_rw(trans);
+       bch2_write_ref_put(c, BCH_WRITE_REF_btree_write_buffer);
+       return ret;
 }
 
-int bch2_btree_insert_keys_write_buffer(struct btree_trans *trans)
+static void bch2_btree_write_buffer_flush_work(struct work_struct *work)
 {
-       struct bch_fs *c = trans->c;
+       struct bch_fs *c = container_of(work, struct bch_fs, btree_write_buffer.flush_work);
        struct btree_write_buffer *wb = &c->btree_write_buffer;
-       struct btree_write_buffered_key *i;
-       union btree_write_buffer_state old, new;
-       int ret = 0;
-       u64 v;
+       int ret;
+
+       mutex_lock(&wb->flushing.lock);
+       do {
+               ret = bch2_trans_run(c, bch2_btree_write_buffer_flush_locked(trans));
+       } while (!ret && bch2_btree_write_buffer_should_flush(c));
+       mutex_unlock(&wb->flushing.lock);
+
+       bch2_write_ref_put(c, BCH_WRITE_REF_btree_write_buffer);
+}
 
-       trans_for_each_wb_update(trans, i) {
-               EBUG_ON(i->k.k.u64s > BTREE_WRITE_BUFERED_U64s_MAX);
+int bch2_journal_key_to_wb_slowpath(struct bch_fs *c,
+                            struct journal_keys_to_wb *dst,
+                            enum btree_id btree, struct bkey_i *k)
+{
+       struct btree_write_buffer *wb = &c->btree_write_buffer;
+       int ret;
+retry:
+       ret = darray_make_room_gfp(&dst->wb->keys, 1, GFP_KERNEL);
+       if (!ret && dst->wb == &wb->flushing)
+               ret = darray_resize(&wb->sorted, wb->flushing.keys.size);
+
+       if (unlikely(ret)) {
+               if (dst->wb == &c->btree_write_buffer.flushing) {
+                       mutex_unlock(&dst->wb->lock);
+                       dst->wb = &c->btree_write_buffer.inc;
+                       bch2_journal_pin_add(&c->journal, dst->seq, &dst->wb->pin,
+                                            bch2_btree_write_buffer_journal_flush);
+                       goto retry;
+               }
 
-               i->journal_seq          = trans->journal_res.seq;
-               i->journal_offset       = trans->journal_res.offset;
+               return ret;
        }
 
-       preempt_disable();
-       v = READ_ONCE(wb->state.v);
-       do {
-               old.v = new.v = v;
+       dst->room = darray_room(dst->wb->keys);
+       if (dst->wb == &wb->flushing)
+               dst->room = min(dst->room, wb->sorted.size - wb->flushing.keys.nr);
+       BUG_ON(!dst->room);
+       BUG_ON(!dst->seq);
+
+       struct btree_write_buffered_key *wb_k = &darray_top(dst->wb->keys);
+       wb_k->journal_seq       = dst->seq;
+       wb_k->btree             = btree;
+       bkey_copy(&wb_k->k, k);
+       dst->wb->keys.nr++;
+       dst->room--;
+       return 0;
+}
+
+void bch2_journal_keys_to_write_buffer_start(struct bch_fs *c, struct journal_keys_to_wb *dst, u64 seq)
+{
+       struct btree_write_buffer *wb = &c->btree_write_buffer;
+
+       if (mutex_trylock(&wb->flushing.lock)) {
+               mutex_lock(&wb->inc.lock);
+               move_keys_from_inc_to_flushing(wb);
+
+               /*
+                * Attempt to skip wb->inc, and add keys directly to
+                * wb->flushing, saving us a copy later:
+                */
 
-               new.v += btree_write_buffer_ref(new.idx);
-               new.nr += trans->nr_wb_updates;
-               if (new.nr > wb->size) {
-                       ret = -BCH_ERR_btree_insert_need_flush_buffer;
-                       goto out;
+               if (!wb->inc.keys.nr) {
+                       dst->wb = &wb->flushing;
+               } else {
+                       mutex_unlock(&wb->flushing.lock);
+                       dst->wb = &wb->inc;
                }
-       } while ((v = atomic64_cmpxchg_acquire(&wb->state.counter, old.v, new.v)) != old.v);
+       } else {
+               mutex_lock(&wb->inc.lock);
+               dst->wb = &wb->inc;
+       }
 
-       memcpy(wb->keys[new.idx] + old.nr,
-              trans->wb_updates,
-              sizeof(trans->wb_updates[0]) * trans->nr_wb_updates);
+       dst->room = darray_room(dst->wb->keys);
+       if (dst->wb == &wb->flushing)
+               dst->room = min(dst->room, wb->sorted.size - wb->flushing.keys.nr);
+       dst->seq = seq;
 
-       bch2_journal_pin_add(&c->journal, trans->journal_res.seq, &wb->journal_pin,
+       bch2_journal_pin_add(&c->journal, seq, &dst->wb->pin,
                             bch2_btree_write_buffer_journal_flush);
+}
+
+void bch2_journal_keys_to_write_buffer_end(struct bch_fs *c, struct journal_keys_to_wb *dst)
+{
+       struct btree_write_buffer *wb = &c->btree_write_buffer;
 
-       atomic64_sub_return_release(btree_write_buffer_ref(new.idx), &wb->state.counter);
+       if (!dst->wb->keys.nr)
+               bch2_journal_pin_drop(&c->journal, &dst->wb->pin);
+
+       if (bch2_btree_write_buffer_should_flush(c) &&
+           __bch2_write_ref_tryget(c, BCH_WRITE_REF_btree_write_buffer) &&
+           !queue_work(system_unbound_wq, &c->btree_write_buffer.flush_work))
+               bch2_write_ref_put(c, BCH_WRITE_REF_btree_write_buffer);
+
+       if (dst->wb == &wb->flushing)
+               mutex_unlock(&wb->flushing.lock);
+       mutex_unlock(&wb->inc.lock);
+}
+
+static int bch2_journal_keys_to_write_buffer(struct bch_fs *c, struct journal_buf *buf)
+{
+       struct journal_keys_to_wb dst;
+       struct jset_entry *entry;
+       struct bkey_i *k;
+       int ret = 0;
+
+       bch2_journal_keys_to_write_buffer_start(c, &dst, le64_to_cpu(buf->data->seq));
+
+       for_each_jset_entry_type(entry, buf->data, BCH_JSET_ENTRY_write_buffer_keys) {
+               jset_entry_for_each_key(entry, k) {
+                       ret = bch2_journal_key_to_wb(c, &dst, entry->btree_id, k);
+                       if (ret)
+                               goto out;
+               }
+
+               entry->type = BCH_JSET_ENTRY_btree_keys;
+       }
+
+       buf->need_flush_to_write_buffer = false;
 out:
-       preempt_enable();
+       bch2_journal_keys_to_write_buffer_end(c, &dst);
+       return ret;
+}
+
+static int wb_keys_resize(struct btree_write_buffer_keys *wb, size_t new_size)
+{
+       if (wb->keys.size >= new_size)
+               return 0;
+
+       if (!mutex_trylock(&wb->lock))
+               return -EINTR;
+
+       int ret = darray_resize(&wb->keys, new_size);
+       mutex_unlock(&wb->lock);
        return ret;
 }
 
+int bch2_btree_write_buffer_resize(struct bch_fs *c, size_t new_size)
+{
+       struct btree_write_buffer *wb = &c->btree_write_buffer;
+
+       return wb_keys_resize(&wb->flushing, new_size) ?:
+               wb_keys_resize(&wb->inc, new_size);
+}
+
 void bch2_fs_btree_write_buffer_exit(struct bch_fs *c)
 {
        struct btree_write_buffer *wb = &c->btree_write_buffer;
 
-       BUG_ON(wb->state.nr && !bch2_journal_error(&c->journal));
+       BUG_ON((wb->inc.keys.nr || wb->flushing.keys.nr) &&
+              !bch2_journal_error(&c->journal));
 
-       kvfree(wb->keys[1]);
-       kvfree(wb->keys[0]);
+       darray_exit(&wb->sorted);
+       darray_exit(&wb->flushing.keys);
+       darray_exit(&wb->inc.keys);
 }
 
 int bch2_fs_btree_write_buffer_init(struct bch_fs *c)
 {
        struct btree_write_buffer *wb = &c->btree_write_buffer;
 
-       mutex_init(&wb->flush_lock);
-       wb->size = c->opts.btree_write_buffer_size;
+       mutex_init(&wb->inc.lock);
+       mutex_init(&wb->flushing.lock);
+       INIT_WORK(&wb->flush_work, bch2_btree_write_buffer_flush_work);
 
-       wb->keys[0] = kvmalloc_array(wb->size, sizeof(*wb->keys[0]), GFP_KERNEL);
-       wb->keys[1] = kvmalloc_array(wb->size, sizeof(*wb->keys[1]), GFP_KERNEL);
-       if (!wb->keys[0] || !wb->keys[1])
-               return -ENOMEM;
+       /* Will be resized by journal as needed: */
+       unsigned initial_size = 1 << 16;
 
-       return 0;
+       return  darray_make_room(&wb->inc.keys, initial_size) ?:
+               darray_make_room(&wb->flushing.keys, initial_size) ?:
+               darray_make_room(&wb->sorted, initial_size);
 }