]> git.sesse.net Git - bcachefs-tools-debian/blobdiff - libbcachefs/alloc_background.c
Update bcachefs sources to bdf6d7c135 fixup! bcachefs: Kill journal buf bloom filter
[bcachefs-tools-debian] / libbcachefs / alloc_background.c
index 48971fcf2d5bb393c818732e3b0f1be50c179ebc..32ebf6cc9e074a8ecc682e2fde616282846e64a4 100644 (file)
@@ -9,10 +9,12 @@
 #include "btree_update_interior.h"
 #include "btree_gc.h"
 #include "buckets.h"
+#include "buckets_waiting_for_journal.h"
 #include "clock.h"
 #include "debug.h"
 #include "ec.h"
 #include "error.h"
+#include "lru.h"
 #include "recovery.h"
 #include "varint.h"
 
 #include <linux/sort.h>
 #include <trace/events/bcachefs.h>
 
+/* Persistent alloc info: */
+
 static const unsigned BCH_ALLOC_V1_FIELD_BYTES[] = {
 #define x(name, bits) [BCH_ALLOC_FIELD_V1_##name] = bits / 8,
        BCH_ALLOC_FIELDS_V1()
 #undef x
 };
 
-/* Ratelimiting/PD controllers */
-
-static void pd_controllers_update(struct work_struct *work)
-{
-       struct bch_fs *c = container_of(to_delayed_work(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(ca);
-
-               free += bucket_to_sector(ca,
-                               __dev_buckets_free(ca, stats)) << 9;
-               /*
-                * Bytes of internal fragmentation, which can be
-                * reclaimed by copy GC
-                */
-               fragmented += max_t(s64, 0, (bucket_to_sector(ca,
-                                       stats.d[BCH_DATA_user].buckets +
-                                       stats.d[BCH_DATA_cached].buckets) -
-                                 (stats.d[BCH_DATA_user].sectors +
-                                  stats.d[BCH_DATA_cached].sectors)) << 9);
-       }
-
-       bch2_pd_controller_update(&c->copygc_pd, free, fragmented, -1);
-       schedule_delayed_work(&c->pd_controllers_update,
-                             c->pd_controllers_update_seconds * HZ);
-}
-
-/* Persistent alloc info: */
+struct bkey_alloc_unpacked {
+       u64             journal_seq;
+       u64             bucket;
+       u8              dev;
+       u8              gen;
+       u8              oldest_gen;
+       u8              data_type;
+       bool            need_discard:1;
+       bool            need_inc_gen:1;
+#define x(_name, _bits)        u##_bits _name;
+       BCH_ALLOC_FIELDS_V2()
+#undef  x
+};
 
 static inline u64 alloc_field_v1_get(const struct bch_alloc *a,
                                     const void **p, unsigned field)
@@ -155,7 +139,7 @@ static int bch2_alloc_unpack_v2(struct bkey_alloc_unpacked *out,
 
 #define x(_name, _bits)                                                        \
        if (fieldnr < a.v->nr_fields) {                                 \
-               ret = bch2_varint_decode(in, end, &v);                  \
+               ret = bch2_varint_decode_fast(in, end, &v);             \
                if (ret < 0)                                            \
                        return ret;                                     \
                in += ret;                                              \
@@ -172,46 +156,43 @@ static int bch2_alloc_unpack_v2(struct bkey_alloc_unpacked *out,
        return 0;
 }
 
-static void bch2_alloc_pack_v2(struct bkey_alloc_buf *dst,
-                              const struct bkey_alloc_unpacked src)
+static int bch2_alloc_unpack_v3(struct bkey_alloc_unpacked *out,
+                               struct bkey_s_c k)
 {
-       struct bkey_i_alloc_v2 *a = bkey_alloc_v2_init(&dst->k);
-       unsigned nr_fields = 0, last_nonzero_fieldnr = 0;
-       u8 *out = a->v.data;
-       u8 *end = (void *) &dst[1];
-       u8 *last_nonzero_field = out;
-       unsigned bytes;
-
-       a->k.p          = POS(src.dev, src.bucket);
-       a->v.gen        = src.gen;
-       a->v.oldest_gen = src.oldest_gen;
-       a->v.data_type  = src.data_type;
+       struct bkey_s_c_alloc_v3 a = bkey_s_c_to_alloc_v3(k);
+       const u8 *in = a.v->data;
+       const u8 *end = bkey_val_end(a);
+       unsigned fieldnr = 0;
+       int ret;
+       u64 v;
+
+       out->gen        = a.v->gen;
+       out->oldest_gen = a.v->oldest_gen;
+       out->data_type  = a.v->data_type;
+       out->need_discard = BCH_ALLOC_V3_NEED_DISCARD(a.v);
+       out->need_inc_gen = BCH_ALLOC_V3_NEED_INC_GEN(a.v);
+       out->journal_seq = le64_to_cpu(a.v->journal_seq);
 
 #define x(_name, _bits)                                                        \
-       nr_fields++;                                                    \
-                                                                       \
-       if (src._name) {                                                \
-               out += bch2_varint_encode(out, src._name);              \
-                                                                       \
-               last_nonzero_field = out;                               \
-               last_nonzero_fieldnr = nr_fields;                       \
+       if (fieldnr < a.v->nr_fields) {                                 \
+               ret = bch2_varint_decode_fast(in, end, &v);             \
+               if (ret < 0)                                            \
+                       return ret;                                     \
+               in += ret;                                              \
        } else {                                                        \
-               *out++ = 0;                                             \
-       }
+               v = 0;                                                  \
+       }                                                               \
+       out->_name = v;                                                 \
+       if (v != out->_name)                                            \
+               return -1;                                              \
+       fieldnr++;
 
        BCH_ALLOC_FIELDS_V2()
 #undef  x
-       BUG_ON(out > end);
-
-       out = last_nonzero_field;
-       a->v.nr_fields = last_nonzero_fieldnr;
-
-       bytes = (u8 *) out - (u8 *) &a->v;
-       set_bkey_val_bytes(&a->k, bytes);
-       memset_u64s_tail(&a->v, 0, bytes);
+       return 0;
 }
 
-struct bkey_alloc_unpacked bch2_alloc_unpack(struct bkey_s_c k)
+static struct bkey_alloc_unpacked bch2_alloc_unpack(struct bkey_s_c k)
 {
        struct bkey_alloc_unpacked ret = {
                .dev    = k.k->p.inode,
@@ -219,22 +200,89 @@ struct bkey_alloc_unpacked bch2_alloc_unpack(struct bkey_s_c k)
                .gen    = 0,
        };
 
-       if (k.k->type == KEY_TYPE_alloc_v2)
-               bch2_alloc_unpack_v2(&ret, k);
-       else if (k.k->type == KEY_TYPE_alloc)
+       switch (k.k->type) {
+       case KEY_TYPE_alloc:
                bch2_alloc_unpack_v1(&ret, k);
+               break;
+       case KEY_TYPE_alloc_v2:
+               bch2_alloc_unpack_v2(&ret, k);
+               break;
+       case KEY_TYPE_alloc_v3:
+               bch2_alloc_unpack_v3(&ret, k);
+               break;
+       }
+
+       return ret;
+}
 
+void bch2_alloc_to_v4(struct bkey_s_c k, struct bch_alloc_v4 *out)
+{
+       if (k.k->type == KEY_TYPE_alloc_v4) {
+               *out = *bkey_s_c_to_alloc_v4(k).v;
+       } else {
+               struct bkey_alloc_unpacked u = bch2_alloc_unpack(k);
+
+               *out = (struct bch_alloc_v4) {
+                       .journal_seq            = u.journal_seq,
+                       .flags                  = u.need_discard,
+                       .gen                    = u.gen,
+                       .oldest_gen             = u.oldest_gen,
+                       .data_type              = u.data_type,
+                       .stripe_redundancy      = u.stripe_redundancy,
+                       .dirty_sectors          = u.dirty_sectors,
+                       .cached_sectors         = u.cached_sectors,
+                       .io_time[READ]          = u.read_time,
+                       .io_time[WRITE]         = u.write_time,
+                       .stripe                 = u.stripe,
+               };
+       }
+}
+
+struct bkey_i_alloc_v4 *bch2_alloc_to_v4_mut(struct btree_trans *trans, struct bkey_s_c k)
+{
+       struct bkey_i_alloc_v4 *ret;
+
+       if (k.k->type == KEY_TYPE_alloc_v4) {
+               ret = bch2_trans_kmalloc(trans, bkey_bytes(k.k));
+               if (!IS_ERR(ret))
+                       bkey_reassemble(&ret->k_i, k);
+       } else {
+               ret = bch2_trans_kmalloc(trans, sizeof(*ret));
+               if (!IS_ERR(ret)) {
+                       bkey_alloc_v4_init(&ret->k_i);
+                       ret->k.p = k.k->p;
+                       bch2_alloc_to_v4(k, &ret->v);
+               }
+       }
        return ret;
 }
 
-void bch2_alloc_pack(struct bch_fs *c,
-                    struct bkey_alloc_buf *dst,
-                    const struct bkey_alloc_unpacked src)
+struct bkey_i_alloc_v4 *
+bch2_trans_start_alloc_update(struct btree_trans *trans, struct btree_iter *iter,
+                             struct bpos pos)
 {
-       bch2_alloc_pack_v2(dst, src);
+       struct bkey_s_c k;
+       struct bkey_i_alloc_v4 *a;
+       int ret;
+
+       bch2_trans_iter_init(trans, iter, BTREE_ID_alloc, pos,
+                            BTREE_ITER_WITH_UPDATES|
+                            BTREE_ITER_CACHED|
+                            BTREE_ITER_INTENT);
+       k = bch2_btree_iter_peek_slot(iter);
+       ret = bkey_err(k);
+       if (ret) {
+               bch2_trans_iter_exit(trans, iter);
+               return ERR_PTR(ret);
+       }
+
+       a = bch2_alloc_to_v4_mut(trans, k);
+       if (IS_ERR(a))
+               bch2_trans_iter_exit(trans, iter);
+       return a;
 }
 
-static unsigned bch_alloc_val_u64s(const struct bch_alloc *a)
+static unsigned bch_alloc_v1_val_u64s(const struct bch_alloc *a)
 {
        unsigned i, bytes = offsetof(struct bch_alloc, data);
 
@@ -245,920 +293,1011 @@ static unsigned bch_alloc_val_u64s(const struct bch_alloc *a)
        return DIV_ROUND_UP(bytes, sizeof(u64));
 }
 
-const char *bch2_alloc_v1_invalid(const struct bch_fs *c, struct bkey_s_c k)
+int bch2_alloc_v1_invalid(const struct bch_fs *c, struct bkey_s_c k,
+                         int rw, struct printbuf *err)
 {
        struct bkey_s_c_alloc a = bkey_s_c_to_alloc(k);
 
-       if (k.k->p.inode >= c->sb.nr_devices ||
-           !c->devs[k.k->p.inode])
-               return "invalid device";
-
        /* allow for unknown fields */
-       if (bkey_val_u64s(a.k) < bch_alloc_val_u64s(a.v))
-               return "incorrect value size";
+       if (bkey_val_u64s(a.k) < bch_alloc_v1_val_u64s(a.v)) {
+               pr_buf(err, "incorrect value size (%zu < %u)",
+                      bkey_val_u64s(a.k), bch_alloc_v1_val_u64s(a.v));
+               return -EINVAL;
+       }
 
-       return NULL;
+       return 0;
 }
 
-const char *bch2_alloc_v2_invalid(const struct bch_fs *c, struct bkey_s_c k)
+int bch2_alloc_v2_invalid(const struct bch_fs *c, struct bkey_s_c k,
+                         int rw, struct printbuf *err)
 {
        struct bkey_alloc_unpacked u;
 
-       if (k.k->p.inode >= c->sb.nr_devices ||
-           !c->devs[k.k->p.inode])
-               return "invalid device";
-
-       if (bch2_alloc_unpack_v2(&u, k))
-               return "unpack error";
-
-       return NULL;
-}
-
-void bch2_alloc_to_text(struct printbuf *out, struct bch_fs *c,
-                          struct bkey_s_c k)
-{
-       struct bkey_alloc_unpacked u = bch2_alloc_unpack(k);
+       if (bch2_alloc_unpack_v2(&u, k)) {
+               pr_buf(err, "unpack error");
+               return -EINVAL;
+       }
 
-       pr_buf(out, "gen %u oldest_gen %u data_type %u",
-              u.gen, u.oldest_gen, u.data_type);
-#define x(_name, ...)  pr_buf(out, #_name " %llu ", (u64) u._name);
-       BCH_ALLOC_FIELDS_V2()
-#undef  x
+       return 0;
 }
 
-static int bch2_alloc_read_fn(struct bch_fs *c, enum btree_id id,
-                             unsigned level, struct bkey_s_c k)
+int bch2_alloc_v3_invalid(const struct bch_fs *c, struct bkey_s_c k,
+                         int rw, struct printbuf *err)
 {
-       struct bch_dev *ca;
-       struct bucket *g;
        struct bkey_alloc_unpacked u;
 
-       if (level ||
-           (k.k->type != KEY_TYPE_alloc &&
-            k.k->type != KEY_TYPE_alloc_v2))
-               return 0;
-
-       ca = bch_dev_bkey_exists(c, k.k->p.inode);
-       g = bucket(ca, k.k->p.offset);
-       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;
+       if (bch2_alloc_unpack_v3(&u, k)) {
+               pr_buf(err, "unpack error");
+               return -EINVAL;
+       }
 
        return 0;
 }
 
-int bch2_alloc_read(struct bch_fs *c, struct journal_keys *journal_keys)
+int bch2_alloc_v4_invalid(const struct bch_fs *c, struct bkey_s_c k,
+                         int rw, struct printbuf *err)
 {
-       int ret;
+       struct bkey_s_c_alloc_v4 a = bkey_s_c_to_alloc_v4(k);
 
-       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);
+       if (bkey_val_bytes(k.k) != sizeof(struct bch_alloc_v4)) {
+               pr_buf(err, "bad val size (%zu != %zu)",
+                      bkey_val_bytes(k.k), sizeof(struct bch_alloc_v4));
+               return -EINVAL;
+       }
 
-       if (ret) {
-               bch_err(c, "error reading alloc info: %i", ret);
-               return ret;
+       if (rw == WRITE) {
+               if (alloc_data_type(*a.v, a.v->data_type) != a.v->data_type) {
+                       pr_buf(err, "invalid data type (got %u should be %u)",
+                              a.v->data_type, alloc_data_type(*a.v, a.v->data_type));
+                       return -EINVAL;
+               }
+
+               switch (a.v->data_type) {
+               case BCH_DATA_free:
+               case BCH_DATA_need_gc_gens:
+               case BCH_DATA_need_discard:
+                       if (a.v->dirty_sectors ||
+                           a.v->cached_sectors ||
+                           a.v->stripe) {
+                               pr_buf(err, "empty data type free but have data");
+                               return -EINVAL;
+                       }
+                       break;
+               case BCH_DATA_sb:
+               case BCH_DATA_journal:
+               case BCH_DATA_btree:
+               case BCH_DATA_user:
+               case BCH_DATA_parity:
+                       if (!a.v->dirty_sectors) {
+                               pr_buf(err, "data_type %s but dirty_sectors==0",
+                                      bch2_data_types[a.v->data_type]);
+                               return -EINVAL;
+                       }
+                       break;
+               case BCH_DATA_cached:
+                       if (!a.v->cached_sectors ||
+                           a.v->dirty_sectors ||
+                           a.v->stripe) {
+                               pr_buf(err, "data type inconsistency");
+                               return -EINVAL;
+                       }
+
+                       if (!a.v->io_time[READ] &&
+                           test_bit(BCH_FS_CHECK_ALLOC_TO_LRU_REFS_DONE, &c->flags)) {
+                               pr_buf(err, "cached bucket with read_time == 0");
+                               return -EINVAL;
+                       }
+                       break;
+               case BCH_DATA_stripe:
+                       if (!a.v->stripe) {
+                               pr_buf(err, "data_type %s but stripe==0",
+                                      bch2_data_types[a.v->data_type]);
+                               return -EINVAL;
+                       }
+                       break;
+               }
        }
 
        return 0;
 }
 
-static int bch2_alloc_write_key(struct btree_trans *trans,
-                               struct btree_iter *iter,
-                               unsigned flags)
+void bch2_alloc_v4_swab(struct bkey_s k)
 {
-       struct bch_fs *c = trans->c;
-       struct bkey_s_c k;
-       struct bch_dev *ca;
-       struct bucket *g;
-       struct bucket_mark m;
-       struct bkey_alloc_unpacked old_u, new_u;
-       struct bkey_alloc_buf a;
-       int ret;
-retry:
-       bch2_trans_begin(trans);
-
-       ret = bch2_btree_key_cache_flush(trans,
-                       BTREE_ID_alloc, iter->pos);
-       if (ret)
-               goto err;
-
-       k = bch2_btree_iter_peek_slot(iter);
-       ret = bkey_err(k);
-       if (ret)
-               goto err;
-
-       old_u = bch2_alloc_unpack(k);
-
-       percpu_down_read(&c->mark_lock);
-       ca      = bch_dev_bkey_exists(c, iter->pos.inode);
-       g       = bucket(ca, iter->pos.offset);
-       m       = READ_ONCE(g->mark);
-       new_u   = alloc_mem_to_key(iter, g, m);
-       percpu_up_read(&c->mark_lock);
-
-       if (!bkey_alloc_unpacked_cmp(old_u, new_u))
-               return 0;
+       struct bch_alloc_v4 *a = bkey_s_to_alloc_v4(k).v;
+
+       a->journal_seq          = swab64(a->journal_seq);
+       a->flags                = swab32(a->flags);
+       a->dirty_sectors        = swab32(a->dirty_sectors);
+       a->cached_sectors       = swab32(a->cached_sectors);
+       a->io_time[0]           = swab64(a->io_time[0]);
+       a->io_time[1]           = swab64(a->io_time[1]);
+       a->stripe               = swab32(a->stripe);
+       a->nr_external_backpointers = swab32(a->nr_external_backpointers);
+}
 
-       bch2_alloc_pack(c, &a, new_u);
-       bch2_trans_update(trans, iter, &a.k,
-                         BTREE_TRIGGER_NORUN);
-       ret = bch2_trans_commit(trans, NULL, NULL,
-                               BTREE_INSERT_NOFAIL|flags);
-err:
-       if (ret == -EINTR)
-               goto retry;
-       return ret;
+void bch2_alloc_to_text(struct printbuf *out, struct bch_fs *c, struct bkey_s_c k)
+{
+       struct bch_alloc_v4 a;
+
+       bch2_alloc_to_v4(k, &a);
+
+       pr_buf(out, "gen %u oldest_gen %u data_type %s journal_seq %llu need_discard %llu need_inc_gen %llu",
+              a.gen, a.oldest_gen, bch2_data_types[a.data_type],
+              a.journal_seq,
+              BCH_ALLOC_V4_NEED_DISCARD(&a),
+              BCH_ALLOC_V4_NEED_INC_GEN(&a));
+       pr_buf(out, " dirty_sectors %u",        a.dirty_sectors);
+       pr_buf(out, " cached_sectors %u",       a.cached_sectors);
+       pr_buf(out, " stripe %u",               a.stripe);
+       pr_buf(out, " stripe_redundancy %u",    a.stripe_redundancy);
+       pr_buf(out, " read_time %llu",          a.io_time[READ]);
+       pr_buf(out, " write_time %llu",         a.io_time[WRITE]);
 }
 
-int bch2_alloc_write(struct bch_fs *c, unsigned flags)
+int bch2_alloc_read(struct bch_fs *c)
 {
        struct btree_trans trans;
-       struct btree_iter *iter;
+       struct btree_iter iter;
+       struct bkey_s_c k;
+       struct bch_alloc_v4 a;
        struct bch_dev *ca;
-       unsigned i;
-       int ret = 0;
+       int ret;
 
-       bch2_trans_init(&trans, c, BTREE_ITER_MAX, 0);
-       iter = bch2_trans_get_iter(&trans, BTREE_ID_alloc, POS_MIN,
-                                  BTREE_ITER_SLOTS|BTREE_ITER_INTENT);
+       bch2_trans_init(&trans, c, 0, 0);
 
-       for_each_member_device(ca, c, i) {
-               bch2_btree_iter_set_pos(iter,
-                       POS(ca->dev_idx, ca->mi.first_bucket));
+       for_each_btree_key(&trans, iter, BTREE_ID_alloc, POS_MIN,
+                          BTREE_ITER_PREFETCH, k, ret) {
+               /*
+                * Not a fsck error because this is checked/repaired by
+                * bch2_check_alloc_key() which runs later:
+                */
+               if (!bch2_dev_bucket_exists(c, k.k->p))
+                       continue;
 
-               while (iter->pos.offset < ca->mi.nbuckets) {
-                       bch2_trans_cond_resched(&trans);
+               ca = bch_dev_bkey_exists(c, k.k->p.inode);
+               bch2_alloc_to_v4(k, &a);
 
-                       ret = bch2_alloc_write_key(&trans, iter, flags);
-                       if (ret) {
-                               percpu_ref_put(&ca->io_ref);
-                               goto err;
-                       }
-                       bch2_btree_iter_next_slot(iter);
-               }
+               *bucket_gen(ca, k.k->p.offset) = a.gen;
        }
-err:
-       bch2_trans_iter_put(&trans, iter);
+       bch2_trans_iter_exit(&trans, &iter);
+
        bch2_trans_exit(&trans);
+
+       if (ret)
+               bch_err(c, "error reading alloc info: %i", ret);
+
        return ret;
 }
 
-/* Bucket IO clocks: */
+/* Free space/discard btree: */
 
-int bch2_bucket_io_time_reset(struct btree_trans *trans, unsigned dev,
-                             size_t bucket_nr, int rw)
+static int bch2_bucket_do_index(struct btree_trans *trans,
+                               struct bkey_s_c alloc_k,
+                               const struct bch_alloc_v4 *a,
+                               bool set)
 {
        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_alloc_buf *a;
-       struct bkey_alloc_unpacked u;
-       u64 *time, now;
-       int ret = 0;
+       struct bch_dev *ca = bch_dev_bkey_exists(c, alloc_k.k->p.inode);
+       struct btree_iter iter;
+       struct bkey_s_c old;
+       struct bkey_i *k;
+       enum btree_id btree;
+       enum bch_bkey_type old_type = !set ? KEY_TYPE_set : KEY_TYPE_deleted;
+       enum bch_bkey_type new_type =  set ? KEY_TYPE_set : KEY_TYPE_deleted;
+       struct printbuf buf = PRINTBUF;
+       int ret;
 
-       iter = bch2_trans_get_iter(trans, BTREE_ID_alloc, POS(dev, bucket_nr),
-                                  BTREE_ITER_CACHED|
-                                  BTREE_ITER_CACHED_NOFILL|
-                                  BTREE_ITER_INTENT);
-       ret = bch2_btree_iter_traverse(iter);
-       if (ret)
-               goto out;
+       if (a->data_type != BCH_DATA_free &&
+           a->data_type != BCH_DATA_need_discard)
+               return 0;
 
-       a = bch2_trans_kmalloc(trans, sizeof(struct bkey_alloc_buf));
-       ret = PTR_ERR_OR_ZERO(a);
-       if (ret)
-               goto out;
+       k = bch2_trans_kmalloc(trans, sizeof(*k));
+       if (IS_ERR(k))
+               return PTR_ERR(k);
 
-       percpu_down_read(&c->mark_lock);
-       g = bucket(ca, bucket_nr);
-       u = alloc_mem_to_key(iter, g, READ_ONCE(g->mark));
-       percpu_up_read(&c->mark_lock);
+       bkey_init(&k->k);
+       k->k.type = new_type;
 
-       time = rw == READ ? &u.read_time : &u.write_time;
-       now = atomic64_read(&c->io_clock[rw].now);
-       if (*time == now)
-               goto out;
+       switch (a->data_type) {
+       case BCH_DATA_free:
+               btree = BTREE_ID_freespace;
+               k->k.p = alloc_freespace_pos(alloc_k.k->p, *a);
+               bch2_key_resize(&k->k, 1);
+               break;
+       case BCH_DATA_need_discard:
+               btree = BTREE_ID_need_discard;
+               k->k.p = alloc_k.k->p;
+               break;
+       default:
+               return 0;
+       }
+
+       bch2_trans_iter_init(trans, &iter, btree,
+                            bkey_start_pos(&k->k),
+                            BTREE_ITER_INTENT);
+       old = bch2_btree_iter_peek_slot(&iter);
+       ret = bkey_err(old);
+       if (ret)
+               goto err;
 
-       *time = now;
+       if (ca->mi.freespace_initialized &&
+           bch2_trans_inconsistent_on(old.k->type != old_type, trans,
+                       "incorrect key when %s %s btree (got %s should be %s)\n"
+                       "  for %s",
+                       set ? "setting" : "clearing",
+                       bch2_btree_ids[btree],
+                       bch2_bkey_types[old.k->type],
+                       bch2_bkey_types[old_type],
+                       (bch2_bkey_val_to_text(&buf, c, alloc_k), buf.buf))) {
+               ret = -EIO;
+               goto err;
+       }
 
-       bch2_alloc_pack(c, a, u);
-       ret   = bch2_trans_update(trans, iter, &a->k, 0) ?:
-               bch2_trans_commit(trans, NULL, NULL, 0);
-out:
-       bch2_trans_iter_put(trans, iter);
+       ret = bch2_trans_update(trans, &iter, k, 0);
+err:
+       bch2_trans_iter_exit(trans, &iter);
+       printbuf_exit(&buf);
        return ret;
 }
 
-/* Background allocator thread: */
-
-/*
- * Scans for buckets to be invalidated, invalidates them, rewrites prios/gens
- * (marking them as invalidated on disk), then optionally issues discard
- * commands to the newly free buckets, then puts them on the various freelists.
- */
-
-/**
- * wait_buckets_available - wait on reclaimable buckets
- *
- * If there aren't enough available buckets to fill up free_inc, wait until
- * there are.
- */
-static int wait_buckets_available(struct bch_fs *c, struct bch_dev *ca)
+int bch2_trans_mark_alloc(struct btree_trans *trans,
+                         enum btree_id btree_id, unsigned level,
+                         struct bkey_s_c old, struct bkey_i *new,
+                         unsigned flags)
 {
-       unsigned long gc_count = c->gc_count;
-       s64 available;
-       unsigned i;
+       struct bch_fs *c = trans->c;
+       struct bch_alloc_v4 old_a, *new_a;
+       u64 old_lru, new_lru;
        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()) {
-                       ret = 1;
-                       break;
-               }
-
-               if (gc_count != c->gc_count)
-                       ca->inc_gen_really_needs_gc = 0;
-
-               available  = dev_buckets_available(ca);
-               available -= ca->inc_gen_really_needs_gc;
-
-               spin_lock(&c->freelist_lock);
-               for (i = 0; i < RESERVE_NR; i++)
-                       available -= fifo_used(&ca->free[i]);
-               spin_unlock(&c->freelist_lock);
+       /*
+        * Deletion only happens in the device removal path, with
+        * BTREE_TRIGGER_NORUN:
+        */
+       BUG_ON(new->k.type != KEY_TYPE_alloc_v4);
 
-               available = max(available, 0LL);
+       bch2_alloc_to_v4(old, &old_a);
+       new_a = &bkey_i_to_alloc_v4(new)->v;
 
-               if (available > fifo_free(&ca->free_inc) ||
-                   (available &&
-                    !fifo_full(&ca->free[RESERVE_MOVINGGC])))
-                       break;
+       new_a->data_type = alloc_data_type(*new_a, new_a->data_type);
 
-               up_read(&c->gc_lock);
-               schedule();
-               try_to_freeze();
-               down_read(&c->gc_lock);
+       if (new_a->dirty_sectors > old_a.dirty_sectors ||
+           new_a->cached_sectors > old_a.cached_sectors) {
+               new_a->io_time[READ] = max_t(u64, 1, atomic64_read(&c->io_clock[READ].now));
+               new_a->io_time[WRITE]= max_t(u64, 1, atomic64_read(&c->io_clock[WRITE].now));
+               SET_BCH_ALLOC_V4_NEED_INC_GEN(new_a, true);
+               SET_BCH_ALLOC_V4_NEED_DISCARD(new_a, true);
        }
 
-       __set_current_state(TASK_RUNNING);
-       ca->allocator_state = ALLOCATOR_RUNNING;
-       closure_wake_up(&c->freelist_wait);
-
-       return ret;
-}
-
-static bool bch2_can_invalidate_bucket(struct bch_dev *ca, size_t b,
-                                      struct bucket_mark m)
-{
-       u8 gc_gen;
-
-       if (!is_available_bucket(m))
-               return false;
+       if (data_type_is_empty(new_a->data_type) &&
+           BCH_ALLOC_V4_NEED_INC_GEN(new_a) &&
+           !bch2_bucket_is_open_safe(c, new->k.p.inode, new->k.p.offset)) {
+               new_a->gen++;
+               SET_BCH_ALLOC_V4_NEED_INC_GEN(new_a, false);
+       }
 
-       if (m.owned_by_allocator)
-               return false;
+       if (old_a.data_type != new_a->data_type ||
+           (new_a->data_type == BCH_DATA_free &&
+            alloc_freespace_genbits(old_a) != alloc_freespace_genbits(*new_a))) {
+               ret =   bch2_bucket_do_index(trans, old, &old_a, false) ?:
+                       bch2_bucket_do_index(trans, bkey_i_to_s_c(new), new_a, true);
+               if (ret)
+                       return ret;
+       }
 
-       if (ca->buckets_nouse &&
-           test_bit(b, ca->buckets_nouse))
-               return false;
+       if (new_a->data_type == BCH_DATA_cached &&
+           !new_a->io_time[READ])
+               new_a->io_time[READ] = max_t(u64, 1, atomic64_read(&c->io_clock[READ].now));
 
-       gc_gen = bucket_gc_gen(bucket(ca, b));
+       old_lru = alloc_lru_idx(old_a);
+       new_lru = alloc_lru_idx(*new_a);
 
-       if (gc_gen >= BUCKET_GC_GEN_MAX / 2)
-               ca->inc_gen_needs_gc++;
+       if (old_lru != new_lru) {
+               ret = bch2_lru_change(trans, new->k.p.inode, new->k.p.offset,
+                                     old_lru, &new_lru, old);
+               if (ret)
+                       return ret;
 
-       if (gc_gen >= BUCKET_GC_GEN_MAX)
-               ca->inc_gen_really_needs_gc++;
+               if (new_a->data_type == BCH_DATA_cached)
+                       new_a->io_time[READ] = new_lru;
+       }
 
-       return gc_gen < BUCKET_GC_GEN_MAX;
+       return 0;
 }
 
-/*
- * Determines what order we're going to reuse buckets, smallest bucket_key()
- * first.
- */
-
-static unsigned bucket_sort_key(struct bucket *g, struct bucket_mark m,
-                               u64 now, u64 last_seq_ondisk)
+static int bch2_check_alloc_key(struct btree_trans *trans,
+                               struct btree_iter *alloc_iter)
 {
-       unsigned used = bucket_sectors_used(m);
+       struct bch_fs *c = trans->c;
+       struct bch_dev *ca;
+       struct btree_iter discard_iter, freespace_iter;
+       struct bch_alloc_v4 a;
+       unsigned discard_key_type, freespace_key_type;
+       struct bkey_s_c alloc_k, k;
+       struct printbuf buf = PRINTBUF;
+       struct printbuf buf2 = PRINTBUF;
+       int ret;
 
-       if (used) {
-               /*
-                * Prefer to keep buckets that have been read more recently, and
-                * buckets that have more data in them:
-                */
-               u64 last_read = max_t(s64, 0, now - g->io_time[READ]);
-               u32 last_read_scaled = max_t(u64, U32_MAX, div_u64(last_read, used));
+       alloc_k = bch2_btree_iter_peek(alloc_iter);
+       if (!alloc_k.k)
+               return 0;
 
-               return -last_read_scaled;
-       } else {
-               /*
-                * Prefer to use buckets with smaller gc_gen so that we don't
-                * have to walk the btree and recalculate oldest_gen - but shift
-                * off the low bits so that buckets will still have equal sort
-                * keys when there's only a small difference, so that we can
-                * keep sequential buckets together:
-                */
-               return  (bucket_needs_journal_commit(m, last_seq_ondisk) << 4)|
-                       (bucket_gc_gen(g) >> 4);
-       }
-}
+       ret = bkey_err(alloc_k);
+       if (ret)
+               return ret;
 
-static inline int bucket_alloc_cmp(alloc_heap *h,
-                                  struct alloc_heap_entry l,
-                                  struct alloc_heap_entry r)
-{
-       return  cmp_int(l.key, r.key) ?:
-               cmp_int(r.nr, l.nr) ?:
-               cmp_int(l.bucket, r.bucket);
-}
+       if (fsck_err_on(!bch2_dev_bucket_exists(c, alloc_k.k->p), c,
+                       "alloc key for invalid device:bucket %llu:%llu",
+                       alloc_k.k->p.inode, alloc_k.k->p.offset))
+               return bch2_btree_delete_at(trans, alloc_iter, 0);
 
-static inline int bucket_idx_cmp(const void *_l, const void *_r)
-{
-       const struct alloc_heap_entry *l = _l, *r = _r;
+       ca = bch_dev_bkey_exists(c, alloc_k.k->p.inode);
+       if (!ca->mi.freespace_initialized)
+               return 0;
 
-       return cmp_int(l->bucket, r->bucket);
-}
+       bch2_alloc_to_v4(alloc_k, &a);
 
-static void find_reclaimable_buckets_lru(struct bch_fs *c, struct bch_dev *ca)
-{
-       struct bucket_array *buckets;
-       struct alloc_heap_entry e = { 0 };
-       u64 now, last_seq_ondisk;
-       size_t b, i, nr = 0;
+       discard_key_type = a.data_type == BCH_DATA_need_discard
+               ? KEY_TYPE_set : 0;
+       freespace_key_type = a.data_type == BCH_DATA_free
+               ? KEY_TYPE_set : 0;
 
-       down_read(&ca->bucket_lock);
+       bch2_trans_iter_init(trans, &discard_iter, BTREE_ID_need_discard,
+                            alloc_k.k->p, 0);
+       bch2_trans_iter_init(trans, &freespace_iter, BTREE_ID_freespace,
+                            alloc_freespace_pos(alloc_k.k->p, a), 0);
 
-       buckets = bucket_array(ca);
-       ca->alloc_heap.used = 0;
-       now = atomic64_read(&c->io_clock[READ].now);
-       last_seq_ondisk = c->journal.last_seq_ondisk;
+       k = bch2_btree_iter_peek_slot(&discard_iter);
+       ret = bkey_err(k);
+       if (ret)
+               goto err;
 
-       /*
-        * Find buckets with lowest read priority, by building a maxheap sorted
-        * by read priority and repeatedly replacing the maximum element until
-        * all buckets have been visited.
-        */
-       for (b = ca->mi.first_bucket; b < ca->mi.nbuckets; b++) {
-               struct bucket *g = &buckets->b[b];
-               struct bucket_mark m = READ_ONCE(g->mark);
-               unsigned key = bucket_sort_key(g, m, now, last_seq_ondisk);
+       if (fsck_err_on(k.k->type != discard_key_type, c,
+                       "incorrect key in need_discard btree (got %s should be %s)\n"
+                       "  %s",
+                       bch2_bkey_types[k.k->type],
+                       bch2_bkey_types[discard_key_type],
+                       (bch2_bkey_val_to_text(&buf, c, alloc_k), buf.buf))) {
+               struct bkey_i *update =
+                       bch2_trans_kmalloc(trans, sizeof(*update));
 
-               if (!bch2_can_invalidate_bucket(ca, b, m))
-                       continue;
+               ret = PTR_ERR_OR_ZERO(update);
+               if (ret)
+                       goto err;
 
-               if (e.nr && e.bucket + e.nr == b && e.key == key) {
-                       e.nr++;
-               } else {
-                       if (e.nr)
-                               heap_add_or_replace(&ca->alloc_heap, e,
-                                       -bucket_alloc_cmp, NULL);
-
-                       e = (struct alloc_heap_entry) {
-                               .bucket = b,
-                               .nr     = 1,
-                               .key    = key,
-                       };
-               }
+               bkey_init(&update->k);
+               update->k.type  = discard_key_type;
+               update->k.p     = discard_iter.pos;
 
-               cond_resched();
+               ret = bch2_trans_update(trans, &discard_iter, update, 0);
+               if (ret)
+                       goto err;
        }
 
-       if (e.nr)
-               heap_add_or_replace(&ca->alloc_heap, e,
-                               -bucket_alloc_cmp, NULL);
+       k = bch2_btree_iter_peek_slot(&freespace_iter);
+       ret = bkey_err(k);
+       if (ret)
+               goto err;
 
-       for (i = 0; i < ca->alloc_heap.used; i++)
-               nr += ca->alloc_heap.data[i].nr;
+       if (fsck_err_on(k.k->type != freespace_key_type, c,
+                       "incorrect key in freespace btree (got %s should be %s)\n"
+                       "  %s",
+                       bch2_bkey_types[k.k->type],
+                       bch2_bkey_types[freespace_key_type],
+                       (printbuf_reset(&buf),
+                        bch2_bkey_val_to_text(&buf, c, alloc_k), buf.buf))) {
+               struct bkey_i *update =
+                       bch2_trans_kmalloc(trans, sizeof(*update));
+
+               ret = PTR_ERR_OR_ZERO(update);
+               if (ret)
+                       goto err;
 
-       while (nr - ca->alloc_heap.data[0].nr >= ALLOC_SCAN_BATCH(ca)) {
-               nr -= ca->alloc_heap.data[0].nr;
-               heap_pop(&ca->alloc_heap, e, -bucket_alloc_cmp, NULL);
-       }
+               bkey_init(&update->k);
+               update->k.type  = freespace_key_type;
+               update->k.p     = freespace_iter.pos;
+               bch2_key_resize(&update->k, 1);
 
-       up_read(&ca->bucket_lock);
+               ret = bch2_trans_update(trans, &freespace_iter, update, 0);
+               if (ret)
+                       goto err;
+       }
+err:
+fsck_err:
+       bch2_trans_iter_exit(trans, &freespace_iter);
+       bch2_trans_iter_exit(trans, &discard_iter);
+       printbuf_exit(&buf2);
+       printbuf_exit(&buf);
+       return ret;
 }
 
-static void find_reclaimable_buckets_fifo(struct bch_fs *c, struct bch_dev *ca)
+static int bch2_check_discard_freespace_key(struct btree_trans *trans,
+                                           struct btree_iter *iter)
 {
-       struct bucket_array *buckets = bucket_array(ca);
-       struct bucket_mark m;
-       size_t b, start;
+       struct bch_fs *c = trans->c;
+       struct btree_iter alloc_iter;
+       struct bkey_s_c k, freespace_k;
+       struct bch_alloc_v4 a;
+       u64 genbits;
+       struct bpos pos;
+       enum bch_data_type state = iter->btree_id == BTREE_ID_need_discard
+               ? BCH_DATA_need_discard
+               : BCH_DATA_free;
+       struct printbuf buf = PRINTBUF;
+       int ret;
 
-       if (ca->fifo_last_bucket <  ca->mi.first_bucket ||
-           ca->fifo_last_bucket >= ca->mi.nbuckets)
-               ca->fifo_last_bucket = ca->mi.first_bucket;
+       freespace_k = bch2_btree_iter_peek(iter);
+       if (!freespace_k.k)
+               return 1;
 
-       start = ca->fifo_last_bucket;
+       ret = bkey_err(freespace_k);
+       if (ret)
+               return ret;
 
-       do {
-               ca->fifo_last_bucket++;
-               if (ca->fifo_last_bucket == ca->mi.nbuckets)
-                       ca->fifo_last_bucket = ca->mi.first_bucket;
+       pos = iter->pos;
+       pos.offset &= ~(~0ULL << 56);
+       genbits = iter->pos.offset & (~0ULL << 56);
 
-               b = ca->fifo_last_bucket;
-               m = READ_ONCE(buckets->b[b].mark);
+       bch2_trans_iter_init(trans, &alloc_iter, BTREE_ID_alloc, pos, 0);
 
-               if (bch2_can_invalidate_bucket(ca, b, m)) {
-                       struct alloc_heap_entry e = { .bucket = b, .nr = 1, };
+       if (fsck_err_on(!bch2_dev_bucket_exists(c, pos), c,
+                       "entry in %s btree for nonexistant dev:bucket %llu:%llu",
+                       bch2_btree_ids[iter->btree_id], pos.inode, pos.offset))
+               goto delete;
 
-                       heap_add(&ca->alloc_heap, e, bucket_alloc_cmp, NULL);
-                       if (heap_full(&ca->alloc_heap))
-                               break;
-               }
+       k = bch2_btree_iter_peek_slot(&alloc_iter);
+       ret = bkey_err(k);
+       if (ret)
+               goto err;
 
-               cond_resched();
-       } while (ca->fifo_last_bucket != start);
+       bch2_alloc_to_v4(k, &a);
+
+       if (fsck_err_on(a.data_type != state ||
+                       (state == BCH_DATA_free &&
+                        genbits != alloc_freespace_genbits(a)), c,
+                       "%s\n  incorrectly set in %s index (free %u, genbits %llu should be %llu)",
+                       (bch2_bkey_val_to_text(&buf, c, k), buf.buf),
+                       bch2_btree_ids[iter->btree_id],
+                       a.data_type == state,
+                       genbits >> 56, alloc_freespace_genbits(a) >> 56))
+               goto delete;
+out:
+err:
+fsck_err:
+       bch2_trans_iter_exit(trans, &alloc_iter);
+       printbuf_exit(&buf);
+       return ret;
+delete:
+       ret = bch2_btree_delete_extent_at(trans, iter,
+                       iter->btree_id == BTREE_ID_freespace ? 1 : 0, 0);
+       goto out;
 }
 
-static void find_reclaimable_buckets_random(struct bch_fs *c, struct bch_dev *ca)
+int bch2_check_alloc_info(struct bch_fs *c)
 {
-       struct bucket_array *buckets = bucket_array(ca);
-       struct bucket_mark m;
-       size_t checked, i;
+       struct btree_trans trans;
+       struct btree_iter iter;
+       struct bkey_s_c k;
+       int ret = 0;
 
-       for (checked = 0;
-            checked < ca->mi.nbuckets / 2;
-            checked++) {
-               size_t b = bch2_rand_range(ca->mi.nbuckets -
-                                          ca->mi.first_bucket) +
-                       ca->mi.first_bucket;
+       bch2_trans_init(&trans, c, 0, 0);
 
-               m = READ_ONCE(buckets->b[b].mark);
+       for_each_btree_key(&trans, iter, BTREE_ID_alloc, POS_MIN,
+                          BTREE_ITER_PREFETCH, k, ret) {
+               ret = __bch2_trans_do(&trans, NULL, NULL, 0,
+                       bch2_check_alloc_key(&trans, &iter));
+               if (ret)
+                       break;
+       }
+       bch2_trans_iter_exit(&trans, &iter);
 
-               if (bch2_can_invalidate_bucket(ca, b, m)) {
-                       struct alloc_heap_entry e = { .bucket = b, .nr = 1, };
+       if (ret)
+               goto err;
 
-                       heap_add(&ca->alloc_heap, e, bucket_alloc_cmp, NULL);
-                       if (heap_full(&ca->alloc_heap))
-                               break;
-               }
+       bch2_trans_iter_init(&trans, &iter, BTREE_ID_need_discard, POS_MIN,
+                            BTREE_ITER_PREFETCH);
+       while (1) {
+               ret = __bch2_trans_do(&trans, NULL, NULL, 0,
+                       bch2_check_discard_freespace_key(&trans, &iter));
+               if (ret)
+                       break;
 
-               cond_resched();
+               bch2_btree_iter_set_pos(&iter, bpos_nosnap_successor(iter.pos));
        }
+       bch2_trans_iter_exit(&trans, &iter);
 
-       sort(ca->alloc_heap.data,
-            ca->alloc_heap.used,
-            sizeof(ca->alloc_heap.data[0]),
-            bucket_idx_cmp, NULL);
+       if (ret)
+               goto err;
 
-       /* remove duplicates: */
-       for (i = 0; i + 1 < ca->alloc_heap.used; i++)
-               if (ca->alloc_heap.data[i].bucket ==
-                   ca->alloc_heap.data[i + 1].bucket)
-                       ca->alloc_heap.data[i].nr = 0;
+       bch2_trans_iter_init(&trans, &iter, BTREE_ID_freespace, POS_MIN,
+                            BTREE_ITER_PREFETCH);
+       while (1) {
+               ret = __bch2_trans_do(&trans, NULL, NULL, 0,
+                       bch2_check_discard_freespace_key(&trans, &iter));
+               if (ret)
+                       break;
+
+               bch2_btree_iter_set_pos(&iter, bpos_nosnap_successor(iter.pos));
+       }
+       bch2_trans_iter_exit(&trans, &iter);
+err:
+       bch2_trans_exit(&trans);
+       return ret < 0 ? ret : 0;
 }
 
-static size_t find_reclaimable_buckets(struct bch_fs *c, struct bch_dev *ca)
+static int bch2_check_alloc_to_lru_ref(struct btree_trans *trans,
+                                      struct btree_iter *alloc_iter)
 {
-       size_t i, nr = 0;
+       struct bch_fs *c = trans->c;
+       struct btree_iter lru_iter;
+       struct bch_alloc_v4 a;
+       struct bkey_s_c alloc_k, k;
+       struct printbuf buf = PRINTBUF;
+       struct printbuf buf2 = PRINTBUF;
+       int ret;
 
-       ca->inc_gen_needs_gc                    = 0;
+       alloc_k = bch2_btree_iter_peek(alloc_iter);
+       if (!alloc_k.k)
+               return 0;
 
-       switch (ca->mi.replacement) {
-       case BCH_CACHE_REPLACEMENT_lru:
-               find_reclaimable_buckets_lru(c, ca);
-               break;
-       case BCH_CACHE_REPLACEMENT_fifo:
-               find_reclaimable_buckets_fifo(c, ca);
-               break;
-       case BCH_CACHE_REPLACEMENT_random:
-               find_reclaimable_buckets_random(c, ca);
-               break;
-       }
+       ret = bkey_err(alloc_k);
+       if (ret)
+               return ret;
 
-       heap_resort(&ca->alloc_heap, bucket_alloc_cmp, NULL);
+       bch2_alloc_to_v4(alloc_k, &a);
 
-       for (i = 0; i < ca->alloc_heap.used; i++)
-               nr += ca->alloc_heap.data[i].nr;
+       if (a.data_type != BCH_DATA_cached)
+               return 0;
 
-       return nr;
-}
+       bch2_trans_iter_init(trans, &lru_iter, BTREE_ID_lru,
+                            POS(alloc_k.k->p.inode, a.io_time[READ]), 0);
 
-static inline long next_alloc_bucket(struct bch_dev *ca)
-{
-       struct alloc_heap_entry e, *top = ca->alloc_heap.data;
+       k = bch2_btree_iter_peek_slot(&lru_iter);
+       ret = bkey_err(k);
+       if (ret)
+               goto err;
+
+       if (fsck_err_on(!a.io_time[READ], c,
+                       "cached bucket with read_time 0\n"
+                       "  %s",
+               (printbuf_reset(&buf),
+                bch2_bkey_val_to_text(&buf, c, alloc_k), buf.buf)) ||
+           fsck_err_on(k.k->type != KEY_TYPE_lru ||
+                       le64_to_cpu(bkey_s_c_to_lru(k).v->idx) != alloc_k.k->p.offset, c,
+                       "incorrect/missing lru entry\n"
+                       "  %s\n"
+                       "  %s",
+                       (printbuf_reset(&buf),
+                        bch2_bkey_val_to_text(&buf, c, alloc_k), buf.buf),
+                       (bch2_bkey_val_to_text(&buf2, c, k), buf2.buf))) {
+               u64 read_time = a.io_time[READ];
+
+               if (!a.io_time[READ])
+                       a.io_time[READ] = atomic64_read(&c->io_clock[READ].now);
+
+               ret = bch2_lru_set(trans,
+                                  alloc_k.k->p.inode,
+                                  alloc_k.k->p.offset,
+                                  &a.io_time[READ]);
+               if (ret)
+                       goto err;
 
-       while (ca->alloc_heap.used) {
-               if (top->nr) {
-                       size_t b = top->bucket;
+               if (a.io_time[READ] != read_time) {
+                       struct bkey_i_alloc_v4 *a_mut =
+                               bch2_alloc_to_v4_mut(trans, alloc_k);
+                       ret = PTR_ERR_OR_ZERO(a_mut);
+                       if (ret)
+                               goto err;
 
-                       top->bucket++;
-                       top->nr--;
-                       return b;
+                       a_mut->v.io_time[READ] = a.io_time[READ];
+                       ret = bch2_trans_update(trans, alloc_iter,
+                                               &a_mut->k_i, BTREE_TRIGGER_NORUN);
+                       if (ret)
+                               goto err;
                }
-
-               heap_pop(&ca->alloc_heap, e, bucket_alloc_cmp, NULL);
        }
-
-       return -1;
+err:
+fsck_err:
+       bch2_trans_iter_exit(trans, &lru_iter);
+       printbuf_exit(&buf2);
+       printbuf_exit(&buf);
+       return ret;
 }
 
-/*
- * 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)
+int bch2_check_alloc_to_lru_refs(struct bch_fs *c)
 {
-       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;
+       struct btree_trans trans;
+       struct btree_iter iter;
+       struct bkey_s_c k;
+       int ret = 0;
 
-               if (bucket_seq > journal_seq)
-                       bucket_seq -= 1 << 16;
+       bch2_trans_init(&trans, c, 0, 0);
 
-               return bucket_seq;
-       } else {
-               return 0;
+       for_each_btree_key(&trans, iter, BTREE_ID_alloc, POS_MIN,
+                          BTREE_ITER_PREFETCH, k, ret) {
+               ret = __bch2_trans_do(&trans, NULL, NULL,
+                                     BTREE_INSERT_NOFAIL|
+                                     BTREE_INSERT_LAZY_RW,
+                       bch2_check_alloc_to_lru_ref(&trans, &iter));
+               if (ret)
+                       break;
        }
+       bch2_trans_iter_exit(&trans, &iter);
+
+       bch2_trans_exit(&trans);
+       return ret < 0 ? ret : 0;
 }
 
-static int bch2_invalidate_one_bucket2(struct btree_trans *trans,
-                                      struct bch_dev *ca,
-                                      struct btree_iter *iter,
-                                      u64 *journal_seq, unsigned flags)
+static int bch2_clear_need_discard(struct btree_trans *trans, struct bpos pos,
+                                  struct bch_dev *ca, bool *discard_done)
 {
        struct bch_fs *c = trans->c;
-       struct bkey_alloc_buf 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;
-
-       /* first, put on free_inc and mark as owned by allocator: */
-       percpu_down_read(&c->mark_lock);
-       g = bucket(ca, b);
-       m = READ_ONCE(g->mark);
+       struct btree_iter iter;
+       struct bkey_s_c k;
+       struct bkey_i_alloc_v4 *a;
+       struct printbuf buf = PRINTBUF;
+       int ret;
 
-       BUG_ON(m.dirty_sectors);
+       bch2_trans_iter_init(trans, &iter, BTREE_ID_alloc, pos,
+                            BTREE_ITER_CACHED);
+       k = bch2_btree_iter_peek_slot(&iter);
+       ret = bkey_err(k);
+       if (ret)
+               goto out;
 
-       bch2_mark_alloc_bucket(c, ca, b, true, gc_pos_alloc(c, NULL), 0);
+       a = bch2_alloc_to_v4_mut(trans, k);
+       ret = PTR_ERR_OR_ZERO(a);
+       if (ret)
+               goto out;
 
-       spin_lock(&c->freelist_lock);
-       verify_not_on_freelist(c, ca, b);
-       BUG_ON(!fifo_push(&ca->free_inc, b));
-       spin_unlock(&c->freelist_lock);
+       if (BCH_ALLOC_V4_NEED_INC_GEN(&a->v)) {
+               a->v.gen++;
+               SET_BCH_ALLOC_V4_NEED_INC_GEN(&a->v, false);
+               goto write;
+       }
 
-       /*
-        * 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 (!m.cached_sectors &&
-           !bucket_needs_journal_commit(m, c->journal.last_seq_ondisk)) {
-               BUG_ON(m.data_type);
-               bucket_cmpxchg(g, m, m.gen++);
-               percpu_up_read(&c->mark_lock);
+       if (bch2_trans_inconsistent_on(a->v.journal_seq > c->journal.flushed_seq_ondisk, trans,
+                       "clearing need_discard but journal_seq %llu > flushed_seq %llu\n"
+                       "%s",
+                       a->v.journal_seq,
+                       c->journal.flushed_seq_ondisk,
+                       (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
+               ret = -EIO;
                goto out;
        }
 
-       percpu_up_read(&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;
+       if (bch2_trans_inconsistent_on(a->v.data_type != BCH_DATA_need_discard, trans,
+                       "bucket incorrectly set in need_discard btree\n"
+                       "%s",
+                       (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
+               ret = -EIO;
                goto out;
        }
 
-       bch2_btree_iter_set_pos(iter, POS(ca->dev_idx, b));
-retry:
-       ret = bch2_btree_iter_traverse(iter);
-       if (ret)
-               return ret;
-
-       percpu_down_read(&c->mark_lock);
-       g = bucket(ca, iter->pos.offset);
-       m = READ_ONCE(g->mark);
-       u = alloc_mem_to_key(iter, g, m);
-
-       percpu_up_read(&c->mark_lock);
+       if (!*discard_done && ca->mi.discard && !c->opts.nochanges) {
+               /*
+                * This works without any other locks because this is the only
+                * thread that removes items from the need_discard tree
+                */
+               bch2_trans_unlock(trans);
+               blkdev_issue_discard(ca->disk_sb.bdev,
+                                    k.k->p.offset * ca->mi.bucket_size,
+                                    ca->mi.bucket_size,
+                                    GFP_KERNEL, 0);
+               *discard_done = true;
+
+               ret = bch2_trans_relock(trans) ? 0 : -EINTR;
+               if (ret)
+                       goto out;
+       }
 
-       invalidating_cached_data = u.cached_sectors != 0;
+       SET_BCH_ALLOC_V4_NEED_DISCARD(&a->v, false);
+       a->v.data_type = alloc_data_type(a->v, a->v.data_type);
+write:
+       ret = bch2_trans_update(trans, &iter, &a->k_i, 0);
+out:
+       bch2_trans_iter_exit(trans, &iter);
+       printbuf_exit(&buf);
+       return ret;
+}
 
-       u.gen++;
-       u.data_type     = 0;
-       u.dirty_sectors = 0;
-       u.cached_sectors = 0;
-       u.read_time     = atomic64_read(&c->io_clock[READ].now);
-       u.write_time    = atomic64_read(&c->io_clock[WRITE].now);
+static void bch2_do_discards_work(struct work_struct *work)
+{
+       struct bch_fs *c = container_of(work, struct bch_fs, discard_work);
+       struct bch_dev *ca = NULL;
+       struct btree_trans trans;
+       struct btree_iter iter;
+       struct bkey_s_c k;
+       u64 seen = 0, open = 0, need_journal_commit = 0, discarded = 0;
+       int ret;
 
-       bch2_alloc_pack(c, &a, u);
-       bch2_trans_update(trans, iter, &a.k,
-                         BTREE_TRIGGER_BUCKET_INVALIDATE);
+       bch2_trans_init(&trans, c, 0, 0);
 
-       /*
-        * 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_JOURNAL_RESERVED|
-                               flags);
-       if (ret == -EINTR)
-               goto retry;
-out:
-       if (!ret) {
-               /* remove from alloc_heap: */
-               struct alloc_heap_entry e, *top = ca->alloc_heap.data;
+       for_each_btree_key(&trans, iter, BTREE_ID_need_discard,
+                          POS_MIN, 0, k, ret) {
+               bool discard_done = false;
 
-               top->bucket++;
-               top->nr--;
+               if (ca && k.k->p.inode != ca->dev_idx) {
+                       percpu_ref_put(&ca->io_ref);
+                       ca = NULL;
+               }
 
-               if (!top->nr)
-                       heap_pop(&ca->alloc_heap, e, bucket_alloc_cmp, NULL);
+               if (!ca) {
+                       ca = bch_dev_bkey_exists(c, k.k->p.inode);
+                       if (!percpu_ref_tryget(&ca->io_ref)) {
+                               ca = NULL;
+                               bch2_btree_iter_set_pos(&iter, POS(k.k->p.inode + 1, 0));
+                               continue;
+                       }
+               }
 
-               /*
-                * 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;
+               seen++;
 
-               /* remove from free_inc: */
-               percpu_down_read(&c->mark_lock);
-               spin_lock(&c->freelist_lock);
+               if (bch2_bucket_is_open_safe(c, k.k->p.inode, k.k->p.offset)) {
+                       open++;
+                       continue;
+               }
 
-               bch2_mark_alloc_bucket(c, ca, b, false,
-                                      gc_pos_alloc(c, NULL), 0);
+               if (bch2_bucket_needs_journal_commit(&c->buckets_waiting_for_journal,
+                               c->journal.flushed_seq_ondisk,
+                               k.k->p.inode, k.k->p.offset)) {
+                       need_journal_commit++;
+                       continue;
+               }
 
-               BUG_ON(!fifo_pop_back(&ca->free_inc, b2));
-               BUG_ON(b != b2);
+               ret = __bch2_trans_do(&trans, NULL, NULL,
+                                     BTREE_INSERT_USE_RESERVE|
+                                     BTREE_INSERT_NOFAIL,
+                               bch2_clear_need_discard(&trans, k.k->p, ca, &discard_done));
+               if (ret)
+                       break;
 
-               spin_unlock(&c->freelist_lock);
-               percpu_up_read(&c->mark_lock);
+               discarded++;
        }
+       bch2_trans_iter_exit(&trans, &iter);
 
-       return ret < 0 ? ret : 0;
-}
-
-/*
- * Pull buckets off ca->alloc_heap, invalidate them, move them to ca->free_inc:
- */
-static int bch2_invalidate_buckets(struct bch_fs *c, struct bch_dev *ca)
-{
-       struct btree_trans trans;
-       struct btree_iter *iter;
-       u64 journal_seq = 0;
-       int ret = 0;
+       if (ca)
+               percpu_ref_put(&ca->io_ref);
 
-       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) &&
-              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_trans_iter_put(&trans, iter);
        bch2_trans_exit(&trans);
 
-       /* If we used NOWAIT, don't return the error: */
-       if (!fifo_empty(&ca->free_inc))
-               ret = 0;
-       if (ret) {
-               bch_err(ca, "error invalidating buckets: %i", ret);
-               return ret;
-       }
+       if (need_journal_commit * 2 > seen)
+               bch2_journal_flush_async(&c->journal, NULL);
 
-       if (journal_seq)
-               ret = bch2_journal_flush_seq(&c->journal, journal_seq);
-       if (ret) {
-               bch_err(ca, "journal error: %i", ret);
-               return ret;
-       }
+       percpu_ref_put(&c->writes);
 
-       return 0;
+       trace_discard_buckets(c, seen, open, need_journal_commit, discarded, ret);
 }
 
-static int push_invalidated_bucket(struct bch_fs *c, struct bch_dev *ca, size_t bucket)
+void bch2_do_discards(struct bch_fs *c)
 {
-       unsigned i;
-       int ret = 0;
+       if (percpu_ref_tryget(&c->writes) &&
+           !queue_work(system_long_wq, &c->discard_work))
+               percpu_ref_put(&c->writes);
+}
 
-       while (1) {
-               set_current_state(TASK_INTERRUPTIBLE);
+static int invalidate_one_bucket(struct btree_trans *trans, struct bch_dev *ca)
+{
+       struct bch_fs *c = trans->c;
+       struct btree_iter lru_iter, alloc_iter = { NULL };
+       struct bkey_s_c k;
+       struct bkey_i_alloc_v4 *a;
+       u64 bucket, idx;
+       struct printbuf buf = PRINTBUF;
+       int ret;
 
-               spin_lock(&c->freelist_lock);
-               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;
+       bch2_trans_iter_init(trans, &lru_iter, BTREE_ID_lru,
+                            POS(ca->dev_idx, 0), 0);
+next_lru:
+       k = bch2_btree_iter_peek(&lru_iter);
+       ret = bkey_err(k);
+       if (ret)
+               goto out;
 
-                       if (fifo_push(&ca->free[i], bucket)) {
-                               fifo_pop(&ca->free_inc, bucket);
+       if (!k.k || k.k->p.inode != ca->dev_idx)
+               goto out;
 
-                               closure_wake_up(&c->freelist_wait);
-                               ca->allocator_state = ALLOCATOR_RUNNING;
+       if (k.k->type != KEY_TYPE_lru) {
+               pr_buf(&buf, "non lru key in lru btree:\n  ");
+               bch2_bkey_val_to_text(&buf, c, k);
 
-                               spin_unlock(&c->freelist_lock);
-                               goto out;
-                       }
+               if (!test_bit(BCH_FS_CHECK_LRUS_DONE, &c->flags)) {
+                       bch_err(c, "%s", buf.buf);
+                       bch2_btree_iter_advance(&lru_iter);
+                       goto next_lru;
+               } else {
+                       bch2_trans_inconsistent(trans, "%s", buf.buf);
+                       ret = -EINVAL;
+                       goto out;
                }
+       }
 
-               if (ca->allocator_state != ALLOCATOR_BLOCKED_FULL) {
-                       ca->allocator_state = ALLOCATOR_BLOCKED_FULL;
-                       closure_wake_up(&c->freelist_wait);
-               }
+       idx     = k.k->p.offset;
+       bucket  = le64_to_cpu(bkey_s_c_to_lru(k).v->idx);
 
-               spin_unlock(&c->freelist_lock);
+       a = bch2_trans_start_alloc_update(trans, &alloc_iter,
+                                         POS(ca->dev_idx, bucket));
+       ret = PTR_ERR_OR_ZERO(a);
+       if (ret)
+               goto out;
 
-               if ((current->flags & PF_KTHREAD) &&
-                   kthread_should_stop()) {
-                       ret = 1;
-                       break;
-               }
+       if (idx != alloc_lru_idx(a->v)) {
+               pr_buf(&buf, "alloc key does not point back to lru entry when invalidating bucket:\n  ");
+               bch2_bkey_val_to_text(&buf, c, bkey_i_to_s_c(&a->k_i));
+               pr_buf(&buf, "\n  ");
+               bch2_bkey_val_to_text(&buf, c, k);
 
-               schedule();
-               try_to_freeze();
+               if (!test_bit(BCH_FS_CHECK_LRUS_DONE, &c->flags)) {
+                       bch_err(c, "%s", buf.buf);
+                       bch2_btree_iter_advance(&lru_iter);
+                       goto next_lru;
+               } else {
+                       bch2_trans_inconsistent(trans, "%s", buf.buf);
+                       ret = -EINVAL;
+                       goto out;
+               }
        }
+
+       SET_BCH_ALLOC_V4_NEED_INC_GEN(&a->v, false);
+       a->v.gen++;
+       a->v.data_type          = 0;
+       a->v.dirty_sectors      = 0;
+       a->v.cached_sectors     = 0;
+       a->v.io_time[READ]      = atomic64_read(&c->io_clock[READ].now);
+       a->v.io_time[WRITE]     = atomic64_read(&c->io_clock[WRITE].now);
+
+       ret = bch2_trans_update(trans, &alloc_iter, &a->k_i,
+                               BTREE_TRIGGER_BUCKET_INVALIDATE);
+       if (ret)
+               goto out;
+
+       trace_invalidate_bucket(c, a->k.p.inode, a->k.p.offset);
 out:
-       __set_current_state(TASK_RUNNING);
+       bch2_trans_iter_exit(trans, &alloc_iter);
+       bch2_trans_iter_exit(trans, &lru_iter);
+       printbuf_exit(&buf);
        return ret;
 }
 
-/*
- * Pulls buckets off free_inc, discards them (if enabled), then adds them to
- * freelists, waiting until there's room if necessary:
- */
-static int discard_invalidated_buckets(struct bch_fs *c, struct bch_dev *ca)
+static void bch2_do_invalidates_work(struct work_struct *work)
 {
-       while (!fifo_empty(&ca->free_inc)) {
-               size_t bucket = fifo_peek(&ca->free_inc);
+       struct bch_fs *c = container_of(work, struct bch_fs, invalidate_work);
+       struct bch_dev *ca;
+       struct btree_trans trans;
+       unsigned i;
+       int ret = 0;
 
-               if (ca->mi.discard &&
-                   blk_queue_discard(bdev_get_queue(ca->disk_sb.bdev)))
-                       blkdev_issue_discard(ca->disk_sb.bdev,
-                                            bucket_to_sector(ca, bucket),
-                                            ca->mi.bucket_size, GFP_NOIO, 0);
+       bch2_trans_init(&trans, c, 0, 0);
 
-               if (push_invalidated_bucket(c, ca, bucket))
-                       return 1;
+       for_each_member_device(ca, c, i) {
+               s64 nr_to_invalidate =
+                       should_invalidate_buckets(ca, bch2_dev_usage_read(ca));
+
+               while (!ret && nr_to_invalidate-- >= 0)
+                       ret = __bch2_trans_do(&trans, NULL, NULL,
+                                             BTREE_INSERT_USE_RESERVE|
+                                             BTREE_INSERT_NOFAIL,
+                                       invalidate_one_bucket(&trans, ca));
        }
 
-       return 0;
+       bch2_trans_exit(&trans);
+       percpu_ref_put(&c->writes);
 }
 
-static inline bool allocator_thread_running(struct bch_dev *ca)
+void bch2_do_invalidates(struct bch_fs *c)
 {
-       return ca->mi.state == BCH_MEMBER_STATE_rw &&
-               test_bit(BCH_FS_ALLOCATOR_RUNNING, &ca->fs->flags);
+       if (percpu_ref_tryget(&c->writes))
+               queue_work(system_long_wq, &c->invalidate_work);
 }
 
-/**
- * bch_allocator_thread - move buckets from free_inc to reserves
- *
- * The free_inc FIFO is populated by find_reclaimable_buckets(), and
- * the reserves are depleted by bucket allocation. When we run out
- * of free_inc, try to invalidate some buckets and write out
- * prios and gens.
- */
-static int bch2_allocator_thread(void *arg)
+static int bch2_dev_freespace_init(struct bch_fs *c, struct bch_dev *ca)
 {
-       struct bch_dev *ca = arg;
-       struct bch_fs *c = ca->fs;
-       size_t nr;
+       struct btree_trans trans;
+       struct btree_iter iter;
+       struct bkey_s_c k;
+       struct bch_alloc_v4 a;
+       struct bch_member *m;
        int ret;
 
-       set_freezable();
-
-       while (1) {
-               if (!allocator_thread_running(ca)) {
-                       ca->allocator_state = ALLOCATOR_STOPPED;
-                       if (kthread_wait_freezable(allocator_thread_running(ca)))
-                               break;
-               }
+       bch2_trans_init(&trans, c, 0, 0);
 
-               ca->allocator_state = ALLOCATOR_RUNNING;
+       for_each_btree_key(&trans, iter, BTREE_ID_alloc,
+                          POS(ca->dev_idx, ca->mi.first_bucket),
+                          BTREE_ITER_SLOTS|
+                          BTREE_ITER_PREFETCH, k, ret) {
+               if (iter.pos.offset >= ca->mi.nbuckets)
+                       break;
 
-               cond_resched();
-               if (kthread_should_stop())
+               bch2_alloc_to_v4(k, &a);
+               ret = __bch2_trans_do(&trans, NULL, NULL,
+                                     BTREE_INSERT_LAZY_RW,
+                                bch2_bucket_do_index(&trans, k, &a, true));
+               if (ret)
                        break;
+       }
+       bch2_trans_iter_exit(&trans, &iter);
 
-               pr_debug("discarding %zu invalidated buckets",
-                        fifo_used(&ca->free_inc));
+       bch2_trans_exit(&trans);
 
-               ret = discard_invalidated_buckets(c, ca);
-               if (ret)
-                       goto stop;
+       if (ret) {
+               bch_err(ca, "error initializing free space: %i", ret);
+               return ret;
+       }
 
-               down_read(&c->gc_lock);
+       mutex_lock(&c->sb_lock);
+       m = bch2_sb_get_members(c->disk_sb.sb)->members + ca->dev_idx;
+       SET_BCH_MEMBER_FREESPACE_INITIALIZED(m, true);
+       mutex_unlock(&c->sb_lock);
 
-               ret = bch2_invalidate_buckets(c, ca);
-               if (ret) {
-                       up_read(&c->gc_lock);
-                       goto stop;
-               }
+       return ret;
+}
 
-               if (!fifo_empty(&ca->free_inc)) {
-                       up_read(&c->gc_lock);
-                       continue;
-               }
+int bch2_fs_freespace_init(struct bch_fs *c)
+{
+       struct bch_dev *ca;
+       unsigned i;
+       int ret = 0;
+       bool doing_init = false;
 
-               pr_debug("free_inc now empty");
+       /*
+        * We can crash during the device add path, so we need to check this on
+        * every mount:
+        */
 
-               do {
-                       /*
-                        * Find some buckets that we can invalidate, either
-                        * they're completely unused, or only contain clean data
-                        * that's been written back to the backing device or
-                        * another cache tier
-                        */
+       for_each_member_device(ca, c, i) {
+               if (ca->mi.freespace_initialized)
+                       continue;
 
-                       pr_debug("scanning for reclaimable buckets");
+               if (!doing_init) {
+                       bch_info(c, "initializing freespace");
+                       doing_init = true;
+               }
 
-                       nr = find_reclaimable_buckets(c, ca);
+               ret = bch2_dev_freespace_init(c, ca);
+               if (ret) {
+                       percpu_ref_put(&ca->ref);
+                       return ret;
+               }
+       }
 
-                       pr_debug("found %zu buckets", nr);
+       if (doing_init) {
+               mutex_lock(&c->sb_lock);
+               bch2_write_super(c);
+               mutex_unlock(&c->sb_lock);
 
-                       trace_alloc_batch(ca, nr, ca->alloc_heap.size);
+               bch_verbose(c, "done initializing freespace");
+       }
 
-                       if ((ca->inc_gen_needs_gc >= ALLOC_SCAN_BATCH(ca) ||
-                            ca->inc_gen_really_needs_gc) &&
-                           c->gc_thread) {
-                               atomic_inc(&c->kick_gc);
-                               wake_up_process(c->gc_thread);
-                       }
+       return ret;
+}
 
-                       /*
-                        * If we found any buckets, we have to invalidate them
-                        * before we scan for more - but if we didn't find very
-                        * many we may want to wait on more buckets being
-                        * available so we don't spin:
-                        */
-                       if (!nr ||
-                           (nr < ALLOC_SCAN_BATCH(ca) &&
-                            !fifo_empty(&ca->free[RESERVE_NONE]))) {
-                               ret = wait_buckets_available(c, ca);
-                               if (ret) {
-                                       up_read(&c->gc_lock);
-                                       goto stop;
-                               }
-                       }
-               } while (!nr);
+/* Bucket IO clocks: */
 
-               up_read(&c->gc_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 btree_iter iter;
+       struct bkey_i_alloc_v4 *a;
+       u64 now;
+       int ret = 0;
 
-               pr_debug("%zu buckets to invalidate", nr);
+       a = bch2_trans_start_alloc_update(trans, &iter,  POS(dev, bucket_nr));
+       ret = PTR_ERR_OR_ZERO(a);
+       if (ret)
+               return ret;
 
-               /*
-                * alloc_heap is now full of newly-invalidated buckets: next,
-                * write out the new bucket gens:
-                */
-       }
+       now = atomic64_read(&c->io_clock[rw].now);
+       if (a->v.io_time[rw] == now)
+               goto out;
 
-stop:
-       pr_debug("alloc thread stopping (ret %i)", ret);
-       ca->allocator_state = ALLOCATOR_STOPPED;
-       closure_wake_up(&c->freelist_wait);
-       return 0;
+       a->v.io_time[rw] = now;
+
+       ret   = bch2_trans_update(trans, &iter, &a->k_i, 0) ?:
+               bch2_trans_commit(trans, NULL, NULL, 0);
+out:
+       bch2_trans_iter_exit(trans, &iter);
+       return ret;
 }
 
 /* Startup/shutdown (ro/rw): */
@@ -1166,15 +1305,15 @@ stop:
 void bch2_recalc_capacity(struct bch_fs *c)
 {
        struct bch_dev *ca;
-       u64 capacity = 0, reserved_sectors = 0, gc_reserve, copygc_threshold = 0;
+       u64 capacity = 0, reserved_sectors = 0, gc_reserve;
        unsigned bucket_size_max = 0;
        unsigned long ra_pages = 0;
-       unsigned i, j;
+       unsigned i;
 
        lockdep_assert_held(&c->state_lock);
 
        for_each_online_member(ca, c, i) {
-               struct backing_dev_info *bdi = ca->disk_sb.bdev->bd_bdi;
+               struct backing_dev_info *bdi = ca->disk_sb.bdev->bd_disk->bdi;
 
                ra_pages += bdi->ra_pages;
        }
@@ -1200,8 +1339,9 @@ void bch2_recalc_capacity(struct bch_fs *c)
                 * allocations for foreground writes must wait -
                 * not -ENOSPC calculations.
                 */
-               for (j = 0; j < RESERVE_NONE; j++)
-                       dev_reserve += ca->free[j].size;
+
+               dev_reserve += ca->nr_btree_reserve * 2;
+               dev_reserve += ca->mi.nbuckets >> 6; /* copygc reserve */
 
                dev_reserve += 1;       /* btree write point */
                dev_reserve += 1;       /* copygc write point */
@@ -1209,8 +1349,6 @@ void bch2_recalc_capacity(struct bch_fs *c)
 
                dev_reserve *= ca->mi.bucket_size;
 
-               copygc_threshold += dev_reserve;
-
                capacity += bucket_to_sector(ca, ca->mi.nbuckets -
                                             ca->mi.first_bucket);
 
@@ -1228,7 +1366,6 @@ 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;
@@ -1247,7 +1384,7 @@ static bool bch2_dev_has_open_write_point(struct bch_fs *c, struct bch_dev *ca)
             ob++) {
                spin_lock(&ob->lock);
                if (ob->valid && !ob->on_partial_list &&
-                   ob->ptr.dev == ca->dev_idx)
+                   ob->dev == ca->dev_idx)
                        ret = true;
                spin_unlock(&ob->lock);
        }
@@ -1260,8 +1397,6 @@ void bch2_dev_allocator_remove(struct bch_fs *c, struct bch_dev *ca)
 {
        unsigned i;
 
-       BUG_ON(ca->alloc_thread);
-
        /* First, remove device from allocation groups: */
 
        for (i = 0; i < ARRAY_SIZE(c->rw_devs); i++)
@@ -1335,65 +1470,9 @@ void bch2_dev_allocator_add(struct bch_fs *c, struct bch_dev *ca)
                        set_bit(ca->dev_idx, c->rw_devs[i].d);
 }
 
-void bch2_dev_allocator_quiesce(struct bch_fs *c, struct bch_dev *ca)
-{
-       if (ca->alloc_thread)
-               closure_wait_event(&c->freelist_wait,
-                                  ca->allocator_state != ALLOCATOR_RUNNING);
-}
-
-/* stop allocator thread: */
-void bch2_dev_allocator_stop(struct bch_dev *ca)
-{
-       struct task_struct *p;
-
-       p = rcu_dereference_protected(ca->alloc_thread, 1);
-       ca->alloc_thread = NULL;
-
-       /*
-        * We need an rcu barrier between setting ca->alloc_thread = NULL and
-        * the thread shutting down to avoid bch2_wake_allocator() racing:
-        *
-        * XXX: it would be better to have the rcu barrier be asynchronous
-        * instead of blocking us here
-        */
-       synchronize_rcu();
-
-       if (p) {
-               kthread_stop(p);
-               put_task_struct(p);
-       }
-}
-
-/* start allocator thread: */
-int bch2_dev_allocator_start(struct bch_dev *ca)
-{
-       struct task_struct *p;
-
-       /*
-        * allocator thread already started?
-        */
-       if (ca->alloc_thread)
-               return 0;
-
-       p = kthread_create(bch2_allocator_thread, ca,
-                          "bch-alloc/%s", ca->name);
-       if (IS_ERR(p)) {
-               bch_err(ca->fs, "error creating allocator thread: %li",
-                       PTR_ERR(p));
-               return PTR_ERR(p);
-       }
-
-       get_task_struct(p);
-       rcu_assign_pointer(ca->alloc_thread, p);
-       wake_up_process(p);
-       return 0;
-}
-
 void bch2_fs_allocator_background_init(struct bch_fs *c)
 {
        spin_lock_init(&c->freelist_lock);
-
-       c->pd_controllers_update_seconds = 5;
-       INIT_DELAYED_WORK(&c->pd_controllers_update, pd_controllers_update);
+       INIT_WORK(&c->discard_work, bch2_do_discards_work);
+       INIT_WORK(&c->invalidate_work, bch2_do_invalidates_work);
 }