]> git.sesse.net Git - bcachefs-tools-debian/blobdiff - libbcachefs/alloc_background.c
Add a subcommand for resizing the journal
[bcachefs-tools-debian] / libbcachefs / alloc_background.c
index 2552d45799ca08ce2c96ecc4ab00288c6a169140..97508de9f7214204f8f6297b0d0d6d6be901732e 100644 (file)
@@ -1,8 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0
 #include "bcachefs.h"
 #include "alloc_background.h"
 #include "alloc_foreground.h"
 #include "btree_cache.h"
 #include "btree_io.h"
+#include "btree_key_cache.h"
 #include "btree_update.h"
 #include "btree_update_interior.h"
 #include "btree_gc.h"
@@ -11,7 +13,7 @@
 #include "debug.h"
 #include "ec.h"
 #include "error.h"
-#include "journal_io.h"
+#include "recovery.h"
 
 #include <linux/kthread.h>
 #include <linux/math64.h>
@@ -39,29 +41,26 @@ static void pd_controllers_update(struct work_struct *work)
                                           struct bch_fs,
                                           pd_controllers_update);
        struct bch_dev *ca;
+       s64 free = 0, fragmented = 0;
        unsigned i;
 
        for_each_member_device(ca, c, i) {
-               struct bch_dev_usage stats = bch2_dev_usage_read(c, ca);
+               struct bch_dev_usage stats = bch2_dev_usage_read(ca);
 
-               u64 free = bucket_to_sector(ca,
+               free += bucket_to_sector(ca,
                                __dev_buckets_free(ca, stats)) << 9;
                /*
                 * Bytes of internal fragmentation, which can be
                 * reclaimed by copy GC
                 */
-               s64 fragmented = (bucket_to_sector(ca,
-                                       stats.buckets[BCH_DATA_USER] +
-                                       stats.buckets[BCH_DATA_CACHED]) -
-                                 (stats.sectors[BCH_DATA_USER] +
-                                  stats.sectors[BCH_DATA_CACHED])) << 9;
-
-               fragmented = max(0LL, fragmented);
-
-               bch2_pd_controller_update(&ca->copygc_pd,
-                                        free, fragmented, -1);
+               fragmented += max_t(s64, 0, (bucket_to_sector(ca,
+                                       stats.buckets[BCH_DATA_user] +
+                                       stats.buckets[BCH_DATA_cached]) -
+                                 (stats.sectors[BCH_DATA_user] +
+                                  stats.sectors[BCH_DATA_cached])) << 9);
        }
 
+       bch2_pd_controller_update(&c->copygc_pd, free, fragmented, -1);
        schedule_delayed_work(&c->pd_controllers_update,
                              c->pd_controllers_update_seconds * HZ);
 }
@@ -128,6 +127,43 @@ static inline void put_alloc_field(struct bkey_i_alloc *a, void **p,
        *p += bytes;
 }
 
+struct bkey_alloc_unpacked bch2_alloc_unpack(struct bkey_s_c k)
+{
+       struct bkey_alloc_unpacked ret = { .gen = 0 };
+
+       if (k.k->type == KEY_TYPE_alloc) {
+               const struct bch_alloc *a = bkey_s_c_to_alloc(k).v;
+               const void *d = a->data;
+               unsigned idx = 0;
+
+               ret.gen = a->gen;
+
+#define x(_name, _bits)        ret._name = get_alloc_field(a, &d, idx++);
+               BCH_ALLOC_FIELDS()
+#undef  x
+       }
+       return ret;
+}
+
+void bch2_alloc_pack(struct bkey_i_alloc *dst,
+                    const struct bkey_alloc_unpacked src)
+{
+       unsigned idx = 0;
+       void *d = dst->v.data;
+       unsigned bytes;
+
+       dst->v.fields   = 0;
+       dst->v.gen      = src.gen;
+
+#define x(_name, _bits)        put_alloc_field(dst, &d, idx++, src._name);
+       BCH_ALLOC_FIELDS()
+#undef  x
+
+       bytes = (void *) d - (void *) &dst->v;
+       set_bkey_val_bytes(&dst->k, bytes);
+       memset_u64s_tail(&dst->v, 0, bytes);
+}
+
 static unsigned bch_alloc_val_u64s(const struct bch_alloc *a)
 {
        unsigned i, bytes = offsetof(struct bch_alloc, data);
@@ -170,87 +206,51 @@ void bch2_alloc_to_text(struct printbuf *out, struct bch_fs *c,
                               get_alloc_field(a.v, &d, i));
 }
 
-static void __alloc_read_key(struct bucket *g, const struct bch_alloc *a)
-{
-       const void *d = a->data;
-       unsigned idx = 0;
-
-       g->_mark.gen            = a->gen;
-       g->gen_valid            = 1;
-       g->io_time[READ]        = get_alloc_field(a, &d, idx++);
-       g->io_time[WRITE]       = get_alloc_field(a, &d, idx++);
-       g->_mark.data_type      = get_alloc_field(a, &d, idx++);
-       g->_mark.dirty_sectors  = get_alloc_field(a, &d, idx++);
-       g->_mark.cached_sectors = get_alloc_field(a, &d, idx++);
-}
-
-static void __alloc_write_key(struct bkey_i_alloc *a, struct bucket *g,
-                             struct bucket_mark m)
-{
-       unsigned idx = 0;
-       void *d = a->v.data;
-
-       a->v.fields     = 0;
-       a->v.gen        = m.gen;
-
-       d = a->v.data;
-       put_alloc_field(a, &d, idx++, g->io_time[READ]);
-       put_alloc_field(a, &d, idx++, g->io_time[WRITE]);
-       put_alloc_field(a, &d, idx++, m.data_type);
-       put_alloc_field(a, &d, idx++, m.dirty_sectors);
-       put_alloc_field(a, &d, idx++, m.cached_sectors);
-
-       set_bkey_val_bytes(&a->k, (void *) d - (void *) &a->v);
-}
-
-static void bch2_alloc_read_key(struct bch_fs *c, struct bkey_s_c k)
+static int bch2_alloc_read_fn(struct bch_fs *c, enum btree_id id,
+                             unsigned level, struct bkey_s_c k)
 {
        struct bch_dev *ca;
-       struct bkey_s_c_alloc a;
-
-       if (k.k->type != KEY_TYPE_alloc)
-               return;
+       struct bucket *g;
+       struct bkey_alloc_unpacked u;
 
-       a = bkey_s_c_to_alloc(k);
-       ca = bch_dev_bkey_exists(c, a.k->p.inode);
+       if (level || k.k->type != KEY_TYPE_alloc)
+               return 0;
 
-       if (a.k->p.offset >= ca->mi.nbuckets)
-               return;
+       ca = bch_dev_bkey_exists(c, k.k->p.inode);
+       g = __bucket(ca, k.k->p.offset, 0);
+       u = bch2_alloc_unpack(k);
+
+       g->_mark.gen            = u.gen;
+       g->_mark.data_type      = u.data_type;
+       g->_mark.dirty_sectors  = u.dirty_sectors;
+       g->_mark.cached_sectors = u.cached_sectors;
+       g->io_time[READ]        = u.read_time;
+       g->io_time[WRITE]       = u.write_time;
+       g->oldest_gen           = u.oldest_gen;
+       g->gen_valid            = 1;
 
-       percpu_down_read_preempt_disable(&c->mark_lock);
-       __alloc_read_key(bucket(ca, a.k->p.offset), a.v);
-       percpu_up_read_preempt_enable(&c->mark_lock);
+       return 0;
 }
 
-int bch2_alloc_read(struct bch_fs *c, struct list_head *journal_replay_list)
+int bch2_alloc_read(struct bch_fs *c, struct journal_keys *journal_keys)
 {
-       struct journal_replay *r;
-       struct btree_iter iter;
-       struct bkey_s_c k;
        struct bch_dev *ca;
        unsigned i;
-       int ret;
+       int ret = 0;
 
-       for_each_btree_key(&iter, c, BTREE_ID_ALLOC, POS_MIN, 0, k) {
-               bch2_alloc_read_key(c, k);
-               bch2_btree_iter_cond_resched(&iter);
-       }
+       down_read(&c->gc_lock);
+       ret = bch2_btree_and_journal_walk(c, journal_keys, BTREE_ID_ALLOC,
+                                         NULL, bch2_alloc_read_fn);
+       up_read(&c->gc_lock);
 
-       ret = bch2_btree_iter_unlock(&iter);
-       if (ret)
+       if (ret) {
+               bch_err(c, "error reading alloc info: %i", ret);
                return ret;
-
-       list_for_each_entry(r, journal_replay_list, list) {
-               struct bkey_i *k, *n;
-               struct jset_entry *entry;
-
-               for_each_jset_key(k, n, entry, &r->j)
-                       if (entry->btree_id == BTREE_ID_ALLOC)
-                               bch2_alloc_read_key(c, bkey_i_to_s_c(k));
        }
 
-       for_each_member_device(ca, c, i)
-               bch2_dev_usage_from_buckets(c, ca);
+       percpu_down_write(&c->mark_lock);
+       bch2_dev_usage_from_buckets(c);
+       percpu_up_write(&c->mark_lock);
 
        mutex_lock(&c->bucket_clock[READ].lock);
        for_each_member_device(ca, c, i) {
@@ -271,137 +271,105 @@ int bch2_alloc_read(struct bch_fs *c, struct list_head *journal_replay_list)
        return 0;
 }
 
-static int __bch2_alloc_write_key(struct bch_fs *c, struct bch_dev *ca,
-                                 size_t b, struct btree_iter *iter,
-                                 u64 *journal_seq, unsigned flags)
+static int bch2_alloc_write_key(struct btree_trans *trans,
+                               struct btree_iter *iter,
+                               unsigned flags)
 {
-#if 0
-       __BKEY_PADDED(k, BKEY_ALLOC_VAL_U64s_MAX) alloc_key;
-#else
-       /* hack: */
-       __BKEY_PADDED(k, 8) alloc_key;
-#endif
-       struct bkey_i_alloc *a = bkey_alloc_init(&alloc_key.k);
+       struct bch_fs *c = trans->c;
+       struct bkey_s_c k;
+       struct bch_dev *ca;
+       struct bucket_array *ba;
        struct bucket *g;
-       struct bucket_mark m, new;
+       struct bucket_mark m;
+       struct bkey_alloc_unpacked old_u, new_u;
+       __BKEY_PADDED(k, 8) alloc_key; /* hack: */
+       struct bkey_i_alloc *a;
        int ret;
+retry:
+       bch2_trans_begin(trans);
 
-       BUG_ON(BKEY_ALLOC_VAL_U64s_MAX > 8);
-
-       a->k.p = POS(ca->dev_idx, b);
-
-       bch2_btree_iter_set_pos(iter, a->k.p);
-
-       ret = bch2_btree_iter_traverse(iter);
+       ret = bch2_btree_key_cache_flush(trans,
+                       BTREE_ID_ALLOC, iter->pos);
        if (ret)
-               return ret;
-
-       percpu_down_read_preempt_disable(&c->mark_lock);
-       g = bucket(ca, b);
-       m = READ_ONCE(g->mark);
+               goto err;
 
-       if (!m.dirty) {
-               percpu_up_read_preempt_enable(&c->mark_lock);
-               return 0;
-       }
+       k = bch2_btree_iter_peek_slot(iter);
+       ret = bkey_err(k);
+       if (ret)
+               goto err;
 
-       __alloc_write_key(a, g, m);
-       percpu_up_read_preempt_enable(&c->mark_lock);
+       old_u = bch2_alloc_unpack(k);
 
-       bch2_btree_iter_cond_resched(iter);
+       percpu_down_read(&c->mark_lock);
+       ca      = bch_dev_bkey_exists(c, iter->pos.inode);
+       ba      = bucket_array(ca);
 
-       ret = bch2_btree_insert_at(c, NULL, journal_seq,
-                                  BTREE_INSERT_NOCHECK_RW|
-                                  BTREE_INSERT_NOFAIL|
-                                  BTREE_INSERT_USE_RESERVE|
-                                  BTREE_INSERT_USE_ALLOC_RESERVE|
-                                  flags,
-                                  BTREE_INSERT_ENTRY(iter, &a->k_i));
-       if (ret)
-               return ret;
+       g       = &ba->b[iter->pos.offset];
+       m       = READ_ONCE(g->mark);
+       new_u   = alloc_mem_to_key(g, m);
+       percpu_up_read(&c->mark_lock);
 
-       new = m;
-       new.dirty = false;
-       atomic64_cmpxchg(&g->_mark.v, m.v.counter, new.v.counter);
+       if (!bkey_alloc_unpacked_cmp(old_u, new_u))
+               return 0;
 
-       if (ca->buckets_written)
-               set_bit(b, ca->buckets_written);
+       a = bkey_alloc_init(&alloc_key.k);
+       a->k.p = iter->pos;
+       bch2_alloc_pack(a, new_u);
 
-       return 0;
+       bch2_trans_update(trans, iter, &a->k_i,
+                         BTREE_TRIGGER_NORUN);
+       ret = bch2_trans_commit(trans, NULL, NULL,
+                               BTREE_INSERT_NOFAIL|
+                               BTREE_INSERT_USE_RESERVE|
+                               flags);
+err:
+       if (ret == -EINTR)
+               goto retry;
+       return ret;
 }
 
-int bch2_alloc_replay_key(struct bch_fs *c, struct bkey_i *k)
+int bch2_dev_alloc_write(struct bch_fs *c, struct bch_dev *ca, unsigned flags)
 {
-       struct bch_dev *ca;
-       struct btree_iter iter;
-       int ret;
+       struct btree_trans trans;
+       struct btree_iter *iter;
+       u64 first_bucket, nbuckets;
+       int ret = 0;
 
-       if (k->k.p.inode >= c->sb.nr_devices ||
-           !c->devs[k->k.p.inode])
-               return 0;
+       percpu_down_read(&c->mark_lock);
+       first_bucket    = bucket_array(ca)->first_bucket;
+       nbuckets        = bucket_array(ca)->nbuckets;
+       percpu_up_read(&c->mark_lock);
 
-       ca = bch_dev_bkey_exists(c, k->k.p.inode);
+       BUG_ON(BKEY_ALLOC_VAL_U64s_MAX > 8);
 
-       if (k->k.p.offset >= ca->mi.nbuckets)
-               return 0;
+       bch2_trans_init(&trans, c, BTREE_ITER_MAX, 0);
 
-       bch2_btree_iter_init(&iter, c, BTREE_ID_ALLOC, k->k.p,
-                            BTREE_ITER_INTENT);
+       iter = bch2_trans_get_iter(&trans, BTREE_ID_ALLOC,
+                                  POS(ca->dev_idx, first_bucket),
+                                  BTREE_ITER_SLOTS|BTREE_ITER_INTENT);
 
-       ret = bch2_btree_iter_traverse(&iter);
-       if (ret)
-               goto err;
+       while (iter->pos.offset < nbuckets) {
+               bch2_trans_cond_resched(&trans);
 
-       /* check buckets_written with btree node locked: */
+               ret = bch2_alloc_write_key(&trans, iter, flags);
+               if (ret)
+                       break;
+               bch2_btree_iter_next_slot(iter);
+       }
+
+       bch2_trans_exit(&trans);
 
-       ret = test_bit(k->k.p.offset, ca->buckets_written)
-               ? 0
-               : bch2_btree_insert_at(c, NULL, NULL,
-                                      BTREE_INSERT_NOFAIL|
-                                      BTREE_INSERT_JOURNAL_REPLAY,
-                                      BTREE_INSERT_ENTRY(&iter, k));
-err:
-       bch2_btree_iter_unlock(&iter);
        return ret;
 }
 
-int bch2_alloc_write(struct bch_fs *c, bool nowait, bool *wrote)
+int bch2_alloc_write(struct bch_fs *c, unsigned flags)
 {
        struct bch_dev *ca;
        unsigned i;
        int ret = 0;
 
-       *wrote = false;
-
        for_each_rw_member(ca, c, i) {
-               struct btree_iter iter;
-               struct bucket_array *buckets;
-               size_t b;
-
-               bch2_btree_iter_init(&iter, c, BTREE_ID_ALLOC, POS_MIN,
-                                    BTREE_ITER_SLOTS|BTREE_ITER_INTENT);
-
-               down_read(&ca->bucket_lock);
-               buckets = bucket_array(ca);
-
-               for (b = buckets->first_bucket;
-                    b < buckets->nbuckets;
-                    b++) {
-                       if (!buckets->b[b].mark.dirty)
-                               continue;
-
-                       ret = __bch2_alloc_write_key(c, ca, b, &iter, NULL,
-                                                    nowait
-                                                    ? BTREE_INSERT_NOWAIT
-                                                    : 0);
-                       if (ret)
-                               break;
-
-                       *wrote = true;
-               }
-               up_read(&ca->bucket_lock);
-               bch2_btree_iter_unlock(&iter);
-
+               bch2_dev_alloc_write(c, ca, flags);
                if (ret) {
                        percpu_ref_put(&ca->io_ref);
                        break;
@@ -521,6 +489,53 @@ static void bch2_bucket_clock_init(struct bch_fs *c, int rw)
        mutex_init(&clock->lock);
 }
 
+int bch2_bucket_io_time_reset(struct btree_trans *trans, unsigned dev,
+                             size_t bucket_nr, int rw)
+{
+       struct bch_fs *c = trans->c;
+       struct bch_dev *ca = bch_dev_bkey_exists(c, dev);
+       struct btree_iter *iter;
+       struct bucket *g;
+       struct bkey_i_alloc *a;
+       struct bkey_alloc_unpacked u;
+       u16 *time;
+       int ret = 0;
+
+       iter = bch2_trans_get_iter(trans, BTREE_ID_ALLOC, POS(dev, bucket_nr),
+                                  BTREE_ITER_CACHED|
+                                  BTREE_ITER_CACHED_NOFILL|
+                                  BTREE_ITER_INTENT);
+       if (IS_ERR(iter))
+               return PTR_ERR(iter);
+
+       a = bch2_trans_kmalloc(trans, BKEY_ALLOC_U64s_MAX * 8);
+       ret = PTR_ERR_OR_ZERO(a);
+       if (ret)
+               goto out;
+
+       percpu_down_read(&c->mark_lock);
+       g = bucket(ca, bucket_nr);
+       u = alloc_mem_to_key(g, READ_ONCE(g->mark));
+       percpu_up_read(&c->mark_lock);
+
+       bkey_alloc_init(&a->k_i);
+       a->k.p = iter->pos;
+
+       time = rw == READ ? &u.read_time : &u.write_time;
+       if (*time == c->bucket_clock[rw].hand)
+               goto out;
+
+       *time = c->bucket_clock[rw].hand;
+
+       bch2_alloc_pack(a, u);
+
+       ret   = bch2_trans_update(trans, iter, &a->k_i, 0) ?:
+               bch2_trans_commit(trans, NULL, NULL, 0);
+out:
+       bch2_trans_iter_put(trans, iter);
+       return ret;
+}
+
 /* Background allocator thread: */
 
 /*
@@ -529,8 +544,6 @@ static void bch2_bucket_clock_init(struct bch_fs *c, int rw)
  * commands to the newly free buckets, then puts them on the various freelists.
  */
 
-#define BUCKET_GC_GEN_MAX      96U
-
 /**
  * wait_buckets_available - wait on reclaimable buckets
  *
@@ -540,8 +553,12 @@ static void bch2_bucket_clock_init(struct bch_fs *c, int rw)
 static int wait_buckets_available(struct bch_fs *c, struct bch_dev *ca)
 {
        unsigned long gc_count = c->gc_count;
+       u64 available;
        int ret = 0;
 
+       ca->allocator_state = ALLOCATOR_BLOCKED;
+       closure_wake_up(&c->freelist_wait);
+
        while (1) {
                set_current_state(TASK_INTERRUPTIBLE);
                if (kthread_should_stop()) {
@@ -552,9 +569,13 @@ static int wait_buckets_available(struct bch_fs *c, struct bch_dev *ca)
                if (gc_count != c->gc_count)
                        ca->inc_gen_really_needs_gc = 0;
 
-               if ((ssize_t) (dev_buckets_available(c, ca) -
-                              ca->inc_gen_really_needs_gc) >=
-                   (ssize_t) fifo_free(&ca->free_inc))
+               available = max_t(s64, 0, dev_buckets_available(ca) -
+                                 ca->inc_gen_really_needs_gc);
+
+               if (available > fifo_free(&ca->free_inc) ||
+                   (available &&
+                    (!fifo_full(&ca->free[RESERVE_BTREE]) ||
+                     !fifo_full(&ca->free[RESERVE_MOVINGGC]))))
                        break;
 
                up_read(&c->gc_lock);
@@ -564,6 +585,9 @@ static int wait_buckets_available(struct bch_fs *c, struct bch_dev *ca)
        }
 
        __set_current_state(TASK_RUNNING);
+       ca->allocator_state = ALLOCATOR_RUNNING;
+       closure_wake_up(&c->freelist_wait);
+
        return ret;
 }
 
@@ -637,16 +661,16 @@ static inline int bucket_alloc_cmp(alloc_heap *h,
                                   struct alloc_heap_entry l,
                                   struct alloc_heap_entry r)
 {
-       return (l.key > r.key) - (l.key < r.key) ?:
-               (l.nr < r.nr)  - (l.nr  > r.nr) ?:
-               (l.bucket > r.bucket) - (l.bucket < r.bucket);
+       return  cmp_int(l.key, r.key) ?:
+               cmp_int(r.nr, l.nr) ?:
+               cmp_int(l.bucket, r.bucket);
 }
 
 static inline int bucket_idx_cmp(const void *_l, const void *_r)
 {
        const struct alloc_heap_entry *l = _l, *r = _r;
 
-       return (l->bucket > r->bucket) - (l->bucket < r->bucket);
+       return cmp_int(l->bucket, r->bucket);
 }
 
 static void find_reclaimable_buckets_lru(struct bch_fs *c, struct bch_dev *ca)
@@ -824,40 +848,174 @@ static inline long next_alloc_bucket(struct bch_dev *ca)
        return -1;
 }
 
-static bool bch2_invalidate_one_bucket(struct bch_fs *c, struct bch_dev *ca,
-                                      size_t bucket, u64 *flush_seq)
+/*
+ * returns sequence number of most recent journal entry that updated this
+ * bucket:
+ */
+static u64 bucket_journal_seq(struct bch_fs *c, struct bucket_mark m)
 {
+       if (m.journal_seq_valid) {
+               u64 journal_seq = atomic64_read(&c->journal.seq);
+               u64 bucket_seq  = journal_seq;
+
+               bucket_seq &= ~((u64) U16_MAX);
+               bucket_seq |= m.journal_seq;
+
+               if (bucket_seq > journal_seq)
+                       bucket_seq -= 1 << 16;
+
+               return bucket_seq;
+       } else {
+               return 0;
+       }
+}
+
+static int bch2_invalidate_one_bucket2(struct btree_trans *trans,
+                                      struct bch_dev *ca,
+                                      struct btree_iter *iter,
+                                      u64 *journal_seq, unsigned flags)
+{
+#if 0
+       __BKEY_PADDED(k, BKEY_ALLOC_VAL_U64s_MAX) alloc_key;
+#else
+       /* hack: */
+       __BKEY_PADDED(k, 8) alloc_key;
+#endif
+       struct bch_fs *c = trans->c;
+       struct bkey_i_alloc *a;
+       struct bkey_alloc_unpacked u;
+       struct bucket *g;
        struct bucket_mark m;
+       bool invalidating_cached_data;
+       size_t b;
+       int ret = 0;
+
+       BUG_ON(!ca->alloc_heap.used ||
+              !ca->alloc_heap.data[0].nr);
+       b = ca->alloc_heap.data[0].bucket;
 
-       percpu_down_read_preempt_disable(&c->mark_lock);
+       /* first, put on free_inc and mark as owned by allocator: */
+       percpu_down_read(&c->mark_lock);
        spin_lock(&c->freelist_lock);
 
-       bch2_invalidate_bucket(c, ca, bucket, &m);
+       verify_not_on_freelist(c, ca, b);
 
-       verify_not_on_freelist(c, ca, bucket);
-       BUG_ON(!fifo_push(&ca->free_inc, bucket));
+       BUG_ON(!fifo_push(&ca->free_inc, b));
+
+       g = bucket(ca, b);
+       m = READ_ONCE(g->mark);
+
+       invalidating_cached_data = m.cached_sectors != 0;
+
+       /*
+        * If we're not invalidating cached data, we only increment the bucket
+        * gen in memory here, the incremented gen will be updated in the btree
+        * by bch2_trans_mark_pointer():
+        */
+
+       if (!invalidating_cached_data)
+               bch2_invalidate_bucket(c, ca, b, &m);
+       else
+               bch2_mark_alloc_bucket(c, ca, b, true, gc_pos_alloc(c, NULL), 0);
 
        spin_unlock(&c->freelist_lock);
+       percpu_up_read(&c->mark_lock);
 
-       bucket_io_clock_reset(c, ca, bucket, READ);
-       bucket_io_clock_reset(c, ca, bucket, WRITE);
+       if (!invalidating_cached_data)
+               goto out;
 
-       percpu_up_read_preempt_enable(&c->mark_lock);
+       /*
+        * If the read-only path is trying to shut down, we can't be generating
+        * new btree updates:
+        */
+       if (test_bit(BCH_FS_ALLOCATOR_STOPPING, &c->flags)) {
+               ret = 1;
+               goto out;
+       }
 
-       if (m.journal_seq_valid) {
-               u64 journal_seq = atomic64_read(&c->journal.seq);
-               u64 bucket_seq  = journal_seq;
+       BUG_ON(BKEY_ALLOC_VAL_U64s_MAX > 8);
 
-               bucket_seq &= ~((u64) U16_MAX);
-               bucket_seq |= m.journal_seq;
+       bch2_btree_iter_set_pos(iter, POS(ca->dev_idx, b));
+retry:
+       ret = bch2_btree_iter_traverse(iter);
+       if (ret)
+               return ret;
 
-               if (bucket_seq > journal_seq)
-                       bucket_seq -= 1 << 16;
+       percpu_down_read(&c->mark_lock);
+       g = bucket(ca, iter->pos.offset);
+       m = READ_ONCE(g->mark);
+       u = alloc_mem_to_key(g, m);
+
+       percpu_up_read(&c->mark_lock);
+
+       invalidating_cached_data = u.cached_sectors != 0;
+
+       u.gen++;
+       u.data_type     = 0;
+       u.dirty_sectors = 0;
+       u.cached_sectors = 0;
+       u.read_time     = c->bucket_clock[READ].hand;
+       u.write_time    = c->bucket_clock[WRITE].hand;
 
-               *flush_seq = max(*flush_seq, bucket_seq);
+       a = bkey_alloc_init(&alloc_key.k);
+       a->k.p = iter->pos;
+       bch2_alloc_pack(a, u);
+
+       bch2_trans_update(trans, iter, &a->k_i,
+                         BTREE_TRIGGER_BUCKET_INVALIDATE);
+
+       /*
+        * XXX:
+        * when using deferred btree updates, we have journal reclaim doing
+        * btree updates and thus requiring the allocator to make forward
+        * progress, and here the allocator is requiring space in the journal -
+        * so we need a journal pre-reservation:
+        */
+       ret = bch2_trans_commit(trans, NULL,
+                               invalidating_cached_data ? journal_seq : NULL,
+                               BTREE_INSERT_NOUNLOCK|
+                               BTREE_INSERT_NOCHECK_RW|
+                               BTREE_INSERT_NOFAIL|
+                               BTREE_INSERT_USE_RESERVE|
+                               BTREE_INSERT_USE_ALLOC_RESERVE|
+                               flags);
+       if (ret == -EINTR)
+               goto retry;
+out:
+       if (!ret) {
+               /* remove from alloc_heap: */
+               struct alloc_heap_entry e, *top = ca->alloc_heap.data;
+
+               top->bucket++;
+               top->nr--;
+
+               if (!top->nr)
+                       heap_pop(&ca->alloc_heap, e, bucket_alloc_cmp, NULL);
+
+               /*
+                * Make sure we flush the last journal entry that updated this
+                * bucket (i.e. deleting the last reference) before writing to
+                * this bucket again:
+                */
+               *journal_seq = max(*journal_seq, bucket_journal_seq(c, m));
+       } else {
+               size_t b2;
+
+               /* remove from free_inc: */
+               percpu_down_read(&c->mark_lock);
+               spin_lock(&c->freelist_lock);
+
+               bch2_mark_alloc_bucket(c, ca, b, false,
+                                      gc_pos_alloc(c, NULL), 0);
+
+               BUG_ON(!fifo_pop_back(&ca->free_inc, b2));
+               BUG_ON(b != b2);
+
+               spin_unlock(&c->freelist_lock);
+               percpu_up_read(&c->mark_lock);
        }
 
-       return m.cached_sectors != 0;
+       return ret < 0 ? ret : 0;
 }
 
 /*
@@ -865,27 +1023,29 @@ static bool bch2_invalidate_one_bucket(struct bch_fs *c, struct bch_dev *ca,
  */
 static int bch2_invalidate_buckets(struct bch_fs *c, struct bch_dev *ca)
 {
-       struct btree_iter iter;
+       struct btree_trans trans;
+       struct btree_iter *iter;
        u64 journal_seq = 0;
        int ret = 0;
-       long b;
 
-       bch2_btree_iter_init(&iter, c, BTREE_ID_ALLOC, POS(ca->dev_idx, 0),
-                            BTREE_ITER_SLOTS|BTREE_ITER_INTENT);
+       bch2_trans_init(&trans, c, 0, 0);
+
+       iter = bch2_trans_get_iter(&trans, BTREE_ID_ALLOC,
+                                  POS(ca->dev_idx, 0),
+                                  BTREE_ITER_CACHED|
+                                  BTREE_ITER_CACHED_NOFILL|
+                                  BTREE_ITER_INTENT);
 
        /* Only use nowait if we've already invalidated at least one bucket: */
        while (!ret &&
               !fifo_full(&ca->free_inc) &&
-              (b = next_alloc_bucket(ca)) >= 0) {
-               bool must_flush =
-                       bch2_invalidate_one_bucket(c, ca, b, &journal_seq);
-
-               ret = __bch2_alloc_write_key(c, ca, b, &iter,
-                               must_flush ? &journal_seq : NULL,
-                               !fifo_empty(&ca->free_inc) ? BTREE_INSERT_NOWAIT : 0);
-       }
+              ca->alloc_heap.used)
+               ret = bch2_invalidate_one_bucket2(&trans, ca, iter, &journal_seq,
+                               BTREE_INSERT_GC_LOCK_HELD|
+                               (!fifo_empty(&ca->free_inc)
+                                ? BTREE_INSERT_NOWAIT : 0));
 
-       bch2_btree_iter_unlock(&iter);
+       bch2_trans_exit(&trans);
 
        /* If we used NOWAIT, don't return the error: */
        if (!fifo_empty(&ca->free_inc))
@@ -914,19 +1074,29 @@ static int push_invalidated_bucket(struct bch_fs *c, struct bch_dev *ca, size_t
                set_current_state(TASK_INTERRUPTIBLE);
 
                spin_lock(&c->freelist_lock);
-               for (i = 0; i < RESERVE_NR; i++)
+               for (i = 0; i < RESERVE_NR; i++) {
+
+                       /*
+                        * Don't strand buckets on the copygc freelist until
+                        * after recovery is finished:
+                        */
+                       if (!test_bit(BCH_FS_STARTED, &c->flags) &&
+                           i == RESERVE_MOVINGGC)
+                               continue;
+
                        if (fifo_push(&ca->free[i], bucket)) {
                                fifo_pop(&ca->free_inc, bucket);
 
                                closure_wake_up(&c->freelist_wait);
-                               ca->allocator_blocked_full = false;
+                               ca->allocator_state = ALLOCATOR_RUNNING;
 
                                spin_unlock(&c->freelist_lock);
                                goto out;
                        }
+               }
 
-               if (!ca->allocator_blocked_full) {
-                       ca->allocator_blocked_full = true;
+               if (ca->allocator_state != ALLOCATOR_BLOCKED_FULL) {
+                       ca->allocator_state = ALLOCATOR_BLOCKED_FULL;
                        closure_wake_up(&c->freelist_wait);
                }
 
@@ -984,9 +1154,12 @@ static int bch2_allocator_thread(void *arg)
        int ret;
 
        set_freezable();
+       ca->allocator_state = ALLOCATOR_RUNNING;
 
        while (1) {
                cond_resched();
+               if (kthread_should_stop())
+                       break;
 
                pr_debug("discarding %zu invalidated buckets",
                         fifo_used(&ca->free_inc));
@@ -1041,10 +1214,7 @@ static int bch2_allocator_thread(void *arg)
                         */
                        if (!nr ||
                            (nr < ALLOC_SCAN_BATCH(ca) &&
-                            !fifo_full(&ca->free[RESERVE_MOVINGGC]))) {
-                               ca->allocator_blocked = true;
-                               closure_wake_up(&c->freelist_wait);
-
+                            !fifo_empty(&ca->free[RESERVE_NONE]))) {
                                ret = wait_buckets_available(c, ca);
                                if (ret) {
                                        up_read(&c->gc_lock);
@@ -1053,7 +1223,6 @@ static int bch2_allocator_thread(void *arg)
                        }
                } while (!nr);
 
-               ca->allocator_blocked = false;
                up_read(&c->gc_lock);
 
                pr_debug("%zu buckets to invalidate", nr);
@@ -1066,6 +1235,8 @@ static int bch2_allocator_thread(void *arg)
 
 stop:
        pr_debug("alloc thread stopping (ret %i)", ret);
+       ca->allocator_state = ALLOCATOR_STOPPED;
+       closure_wake_up(&c->freelist_wait);
        return 0;
 }
 
@@ -1074,7 +1245,7 @@ stop:
 void bch2_recalc_capacity(struct bch_fs *c)
 {
        struct bch_dev *ca;
-       u64 capacity = 0, reserved_sectors = 0, gc_reserve;
+       u64 capacity = 0, reserved_sectors = 0, gc_reserve, copygc_threshold = 0;
        unsigned bucket_size_max = 0;
        unsigned long ra_pages = 0;
        unsigned i, j;
@@ -1117,7 +1288,7 @@ void bch2_recalc_capacity(struct bch_fs *c)
 
                dev_reserve *= ca->mi.bucket_size;
 
-               ca->copygc_threshold = dev_reserve;
+               copygc_threshold += dev_reserve;
 
                capacity += bucket_to_sector(ca, ca->mi.nbuckets -
                                             ca->mi.first_bucket);
@@ -1136,22 +1307,11 @@ void bch2_recalc_capacity(struct bch_fs *c)
 
        reserved_sectors = min(reserved_sectors, capacity);
 
+       c->copygc_threshold = copygc_threshold;
        c->capacity = capacity - reserved_sectors;
 
        c->bucket_size_max = bucket_size_max;
 
-       if (c->capacity) {
-               bch2_io_timer_add(&c->io_clock[READ],
-                                &c->bucket_clock[READ].rescale);
-               bch2_io_timer_add(&c->io_clock[WRITE],
-                                &c->bucket_clock[WRITE].rescale);
-       } else {
-               bch2_io_timer_del(&c->io_clock[READ],
-                                &c->bucket_clock[READ].rescale);
-               bch2_io_timer_del(&c->io_clock[WRITE],
-                                &c->bucket_clock[WRITE].rescale);
-       }
-
        /* Wake up case someone was waiting for buckets */
        closure_wake_up(&c->freelist_wait);
 }
@@ -1195,7 +1355,7 @@ void bch2_dev_allocator_remove(struct bch_fs *c, struct bch_dev *ca)
        for (i = 0; i < ARRAY_SIZE(c->write_points); i++)
                bch2_writepoint_stop(c, ca, &c->write_points[i]);
 
-       bch2_writepoint_stop(c, ca, &ca->copygc_write_point);
+       bch2_writepoint_stop(c, ca, &c->copygc_write_point);
        bch2_writepoint_stop(c, ca, &c->rebalance_write_point);
        bch2_writepoint_stop(c, ca, &c->btree_write_point);
 
@@ -1256,7 +1416,9 @@ void bch2_dev_allocator_add(struct bch_fs *c, struct bch_dev *ca)
 
 void bch2_dev_allocator_quiesce(struct bch_fs *c, struct bch_dev *ca)
 {
-       closure_wait_event(&c->freelist_wait, ca->allocator_blocked_full);
+       if (ca->alloc_thread)
+               closure_wait_event(&c->freelist_wait,
+                                  ca->allocator_state != ALLOCATOR_RUNNING);
 }
 
 /* stop allocator thread: */
@@ -1304,239 +1466,6 @@ int bch2_dev_allocator_start(struct bch_dev *ca)
        return 0;
 }
 
-static void flush_held_btree_writes(struct bch_fs *c)
-{
-       struct bucket_table *tbl;
-       struct rhash_head *pos;
-       struct btree *b;
-       bool nodes_blocked;
-       size_t i;
-       struct closure cl;
-
-       closure_init_stack(&cl);
-
-       clear_bit(BCH_FS_HOLD_BTREE_WRITES, &c->flags);
-again:
-       pr_debug("flushing dirty btree nodes");
-       cond_resched();
-       closure_wait(&c->btree_interior_update_wait, &cl);
-
-       nodes_blocked = false;
-
-       rcu_read_lock();
-       for_each_cached_btree(b, c, tbl, i, pos)
-               if (btree_node_need_write(b)) {
-                       if (btree_node_may_write(b)) {
-                               rcu_read_unlock();
-                               btree_node_lock_type(c, b, SIX_LOCK_read);
-                               bch2_btree_node_write(c, b, SIX_LOCK_read);
-                               six_unlock_read(&b->lock);
-                               goto again;
-                       } else {
-                               nodes_blocked = true;
-                       }
-               }
-       rcu_read_unlock();
-
-       if (c->btree_roots_dirty)
-               bch2_journal_meta(&c->journal);
-
-       if (nodes_blocked) {
-               closure_sync(&cl);
-               goto again;
-       }
-
-       closure_wake_up(&c->btree_interior_update_wait);
-       closure_sync(&cl);
-
-       closure_wait_event(&c->btree_interior_update_wait,
-                          !bch2_btree_interior_updates_nr_pending(c));
-}
-
-static void allocator_start_issue_discards(struct bch_fs *c)
-{
-       struct bch_dev *ca;
-       unsigned dev_iter;
-       size_t bu;
-
-       for_each_rw_member(ca, c, dev_iter)
-               while (fifo_pop(&ca->free_inc, bu))
-                       blkdev_issue_discard(ca->disk_sb.bdev,
-                                            bucket_to_sector(ca, bu),
-                                            ca->mi.bucket_size, GFP_NOIO, 0);
-}
-
-static int resize_free_inc(struct bch_dev *ca)
-{
-       alloc_fifo free_inc;
-
-       if (!fifo_full(&ca->free_inc))
-               return 0;
-
-       if (!init_fifo(&free_inc,
-                      ca->free_inc.size * 2,
-                      GFP_KERNEL))
-               return -ENOMEM;
-
-       fifo_move(&free_inc, &ca->free_inc);
-       swap(free_inc, ca->free_inc);
-       free_fifo(&free_inc);
-       return 0;
-}
-
-static int __bch2_fs_allocator_start(struct bch_fs *c)
-{
-       struct bch_dev *ca;
-       unsigned dev_iter;
-       u64 journal_seq = 0;
-       long bu;
-       int ret = 0;
-
-       if (test_alloc_startup(c))
-               goto not_enough;
-
-       /* Scan for buckets that are already invalidated: */
-       for_each_rw_member(ca, c, dev_iter) {
-               struct bucket_array *buckets;
-               struct bucket_mark m;
-
-               down_read(&ca->bucket_lock);
-               percpu_down_read_preempt_disable(&c->mark_lock);
-
-               buckets = bucket_array(ca);
-
-               for (bu = buckets->first_bucket;
-                    bu < buckets->nbuckets; bu++) {
-                       m = READ_ONCE(buckets->b[bu].mark);
-
-                       if (!buckets->b[bu].gen_valid ||
-                           !test_bit(bu, ca->buckets_nouse) ||
-                           !is_available_bucket(m) ||
-                           m.cached_sectors)
-                               continue;
-
-                       bch2_mark_alloc_bucket(c, ca, bu, true,
-                                       gc_pos_alloc(c, NULL), 0);
-
-                       fifo_push(&ca->free_inc, bu);
-
-                       discard_invalidated_buckets(c, ca);
-
-                       if (fifo_full(&ca->free[RESERVE_BTREE]))
-                               break;
-               }
-               percpu_up_read_preempt_enable(&c->mark_lock);
-               up_read(&ca->bucket_lock);
-       }
-
-       /* did we find enough buckets? */
-       for_each_rw_member(ca, c, dev_iter)
-               if (!fifo_full(&ca->free[RESERVE_BTREE])) {
-                       percpu_ref_put(&ca->io_ref);
-                       goto not_enough;
-               }
-
-       return 0;
-not_enough:
-       pr_debug("not enough empty buckets; scanning for reclaimable buckets");
-
-       /*
-        * We're moving buckets to freelists _before_ they've been marked as
-        * invalidated on disk - we have to so that we can allocate new btree
-        * nodes to mark them as invalidated on disk.
-        *
-        * However, we can't _write_ to any of these buckets yet - they might
-        * have cached data in them, which is live until they're marked as
-        * invalidated on disk:
-        */
-       set_bit(BCH_FS_HOLD_BTREE_WRITES, &c->flags);
-
-       while (1) {
-               bool wrote = false;
-
-               for_each_rw_member(ca, c, dev_iter) {
-                       find_reclaimable_buckets(c, ca);
-
-                       while (!fifo_full(&ca->free[RESERVE_BTREE]) &&
-                              (bu = next_alloc_bucket(ca)) >= 0) {
-                               ret = resize_free_inc(ca);
-                               if (ret) {
-                                       percpu_ref_put(&ca->io_ref);
-                                       return ret;
-                               }
-
-                               bch2_invalidate_one_bucket(c, ca, bu,
-                                                          &journal_seq);
-
-                               fifo_push(&ca->free[RESERVE_BTREE], bu);
-                               bucket_set_dirty(ca, bu);
-                       }
-               }
-
-               pr_debug("done scanning for reclaimable buckets");
-
-               /*
-                * XXX: it's possible for this to deadlock waiting on journal reclaim,
-                * since we're holding btree writes. What then?
-                */
-               ret = bch2_alloc_write(c, true, &wrote);
-
-               /*
-                * If bch2_alloc_write() did anything, it may have used some
-                * buckets, and we need the RESERVE_BTREE freelist full - so we
-                * need to loop and scan again.
-                * And if it errored, it may have been because there weren't
-                * enough buckets, so just scan and loop again as long as it
-                * made some progress:
-                */
-               if (!wrote && ret)
-                       return ret;
-               if (!wrote && !ret)
-                       break;
-       }
-
-       pr_debug("flushing journal");
-
-       ret = bch2_journal_flush(&c->journal);
-       if (ret)
-               return ret;
-
-       pr_debug("issuing discards");
-       allocator_start_issue_discards(c);
-
-       set_bit(BCH_FS_ALLOCATOR_STARTED, &c->flags);
-
-       /* now flush dirty btree nodes: */
-       flush_held_btree_writes(c);
-
-       return 0;
-}
-
-int bch2_fs_allocator_start(struct bch_fs *c)
-{
-       struct bch_dev *ca;
-       unsigned i;
-       bool wrote;
-       int ret;
-
-       down_read(&c->gc_lock);
-       ret = __bch2_fs_allocator_start(c);
-       up_read(&c->gc_lock);
-
-       if (ret)
-               return ret;
-
-       for_each_rw_member(ca, c, i) {
-               ret = bch2_dev_allocator_start(ca);
-               if (ret) {
-                       percpu_ref_put(&ca->io_ref);
-                       return ret;
-               }
-       }
-
-       return bch2_alloc_write(c, false, &wrote);
-}
-
 void bch2_fs_allocator_background_init(struct bch_fs *c)
 {
        spin_lock_init(&c->freelist_lock);