]> git.sesse.net Git - bcachefs-tools-debian/blobdiff - libbcachefs/buckets.c
btree_write_buffer: ensure atomic64_sub_return_release availability
[bcachefs-tools-debian] / libbcachefs / buckets.c
index 43112445040501828e49274b2d1fde18b09f98ad..58d8c6ffd955429d9f13207ddf04c1f687a68b2e 100644 (file)
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Code for manipulating bucket marks for garbage collection.
  *
  * Copyright 2014 Datera, Inc.
- *
- * Bucket states:
- * - free bucket: mark == 0
- *   The bucket contains no data and will not be read
- *
- * - allocator bucket: owned_by_allocator == 1
- *   The bucket is on a free list, or it is an open bucket
- *
- * - cached bucket: owned_by_allocator == 0 &&
- *                  dirty_sectors == 0 &&
- *                  cached_sectors > 0
- *   The bucket contains data but may be safely discarded as there are
- *   enough replicas of the data on other cache devices, or it has been
- *   written back to the backing device
- *
- * - dirty bucket: owned_by_allocator == 0 &&
- *                 dirty_sectors > 0
- *   The bucket contains data that we must not discard (either only copy,
- *   or one of the 'main copies' for data requiring multiple replicas)
- *
- * - metadata bucket: owned_by_allocator == 0 && is_metadata == 1
- *   This is a btree node, journal or gen/prio bucket
- *
- * Lifecycle:
- *
- * bucket invalidated => bucket on freelist => open bucket =>
- *     [dirty bucket =>] cached bucket => bucket invalidated => ...
- *
- * Note that cache promotion can skip the dirty bucket step, as data
- * is copied from a deeper tier to a shallower tier, onto a cached
- * bucket.
- * Note also that a cached bucket can spontaneously become dirty --
- * see below.
- *
- * Only a traversal of the key space can determine whether a bucket is
- * truly dirty or cached.
- *
- * Transitions:
- *
- * - free => allocator: bucket was invalidated
- * - cached => allocator: bucket was invalidated
- *
- * - allocator => dirty: open bucket was filled up
- * - allocator => cached: open bucket was filled up
- * - allocator => metadata: metadata was allocated
- *
- * - dirty => cached: dirty sectors were copied to a deeper tier
- * - dirty => free: dirty sectors were overwritten or moved (copy gc)
- * - cached => free: cached sectors were overwritten
- *
- * - metadata => free: metadata was freed
- *
- * Oddities:
- * - cached => dirty: a device was removed so formerly replicated data
- *                    is no longer sufficiently replicated
- * - free => cached: cannot happen
- * - free => dirty: cannot happen
- * - free => metadata: cannot happen
  */
 
 #include "bcachefs.h"
-#include "alloc.h"
+#include "alloc_background.h"
+#include "backpointers.h"
+#include "bset.h"
 #include "btree_gc.h"
+#include "btree_update.h"
 #include "buckets.h"
+#include "buckets_waiting_for_journal.h"
+#include "ec.h"
 #include "error.h"
+#include "inode.h"
 #include "movinggc.h"
+#include "recovery.h"
+#include "reflink.h"
+#include "replicas.h"
+#include "subvolume.h"
+#include "trace.h"
 
 #include <linux/preempt.h>
-#include <trace/events/bcachefs.h>
-
-#ifdef DEBUG_BUCKETS
 
-#define lg_local_lock  lg_global_lock
-#define lg_local_unlock        lg_global_unlock
+static inline void fs_usage_data_type_to_base(struct bch_fs_usage *fs_usage,
+                                             enum bch_data_type data_type,
+                                             s64 sectors)
+{
+       switch (data_type) {
+       case BCH_DATA_btree:
+               fs_usage->btree         += sectors;
+               break;
+       case BCH_DATA_user:
+       case BCH_DATA_parity:
+               fs_usage->data          += sectors;
+               break;
+       case BCH_DATA_cached:
+               fs_usage->cached        += sectors;
+               break;
+       default:
+               break;
+       }
+}
 
-static void bch2_fs_stats_verify(struct bch_fs *c)
+void bch2_fs_usage_initialize(struct bch_fs *c)
 {
-       struct bch_fs_usage stats =
-               __bch2_fs_usage_read(c);
+       struct bch_fs_usage *usage;
+       struct bch_dev *ca;
        unsigned i;
 
-       for (i = 0; i < ARRAY_SIZE(stats.s); i++) {
-               if ((s64) stats.s[i].data[S_META] < 0)
-                       panic("replicas %u meta underflow: %lli\n",
-                             i + 1, stats.s[i].data[S_META]);
+       percpu_down_write(&c->mark_lock);
+       usage = c->usage_base;
 
-               if ((s64) stats.s[i].data[S_DIRTY] < 0)
-                       panic("replicas %u dirty underflow: %lli\n",
-                             i + 1, stats.s[i].data[S_DIRTY]);
+       for (i = 0; i < ARRAY_SIZE(c->usage); i++)
+               bch2_fs_usage_acc_to_base(c, i);
 
-               if ((s64) stats.s[i].persistent_reserved < 0)
-                       panic("replicas %u reserved underflow: %lli\n",
-                             i + 1, stats.s[i].persistent_reserved);
+       for (i = 0; i < BCH_REPLICAS_MAX; i++)
+               usage->reserved += usage->persistent_reserved[i];
+
+       for (i = 0; i < c->replicas.nr; i++) {
+               struct bch_replicas_entry *e =
+                       cpu_replicas_entry(&c->replicas, i);
+
+               fs_usage_data_type_to_base(usage, e->data_type, usage->replicas[i]);
+       }
+
+       for_each_member_device(ca, c, i) {
+               struct bch_dev_usage dev = bch2_dev_usage_read(ca);
+
+               usage->hidden += (dev.d[BCH_DATA_sb].buckets +
+                                 dev.d[BCH_DATA_journal].buckets) *
+                       ca->mi.bucket_size;
        }
 
-       if ((s64) stats.online_reserved < 0)
-               panic("sectors_online_reserved underflow: %lli\n",
-                     stats.online_reserved);
+       percpu_up_write(&c->mark_lock);
 }
 
-static void bch2_dev_stats_verify(struct bch_dev *ca)
+static inline struct bch_dev_usage *dev_usage_ptr(struct bch_dev *ca,
+                                                 unsigned journal_seq,
+                                                 bool gc)
 {
-       struct bch_dev_usage stats =
-               __bch2_dev_usage_read(ca);
-       u64 n = ca->mi.nbuckets - ca->mi.first_bucket;
-       unsigned i;
+       BUG_ON(!gc && !journal_seq);
 
-       for (i = 0; i < ARRAY_SIZE(stats.buckets); i++)
-               BUG_ON(stats.buckets[i]         > n);
-       BUG_ON(stats.buckets_alloc              > n);
-       BUG_ON(stats.buckets_unavailable        > n);
+       return this_cpu_ptr(gc
+                           ? ca->usage_gc
+                           : ca->usage[journal_seq & JOURNAL_BUF_MASK]);
 }
 
-static void bch2_disk_reservations_verify(struct bch_fs *c, int flags)
+void bch2_dev_usage_read_fast(struct bch_dev *ca, struct bch_dev_usage *usage)
 {
-       if (!(flags & BCH_DISK_RESERVATION_NOFAIL)) {
-               u64 used = __bch2_fs_sectors_used(c);
-               u64 cached = 0;
-               u64 avail = atomic64_read(&c->sectors_available);
-               int cpu;
+       struct bch_fs *c = ca->fs;
+       unsigned seq, i, u64s = dev_usage_u64s();
 
-               for_each_possible_cpu(cpu)
-                       cached += per_cpu_ptr(c->usage_percpu, cpu)->available_cache;
+       do {
+               seq = read_seqcount_begin(&c->usage_lock);
+               memcpy(usage, ca->usage_base, u64s * sizeof(u64));
+               for (i = 0; i < ARRAY_SIZE(ca->usage); i++)
+                       acc_u64s_percpu((u64 *) usage, (u64 __percpu *) ca->usage[i], u64s);
+       } while (read_seqcount_retry(&c->usage_lock, seq));
+}
 
-               if (used + avail + cached > c->capacity)
-                       panic("used %llu avail %llu cached %llu capacity %llu\n",
-                             used, avail, cached, c->capacity);
-       }
+u64 bch2_fs_usage_read_one(struct bch_fs *c, u64 *v)
+{
+       ssize_t offset = v - (u64 *) c->usage_base;
+       unsigned i, seq;
+       u64 ret;
+
+       BUG_ON(offset < 0 || offset >= fs_usage_u64s(c));
+       percpu_rwsem_assert_held(&c->mark_lock);
+
+       do {
+               seq = read_seqcount_begin(&c->usage_lock);
+               ret = *v;
+
+               for (i = 0; i < ARRAY_SIZE(c->usage); i++)
+                       ret += percpu_u64_get((u64 __percpu *) c->usage[i] + offset);
+       } while (read_seqcount_retry(&c->usage_lock, seq));
+
+       return ret;
 }
 
-#else
+struct bch_fs_usage_online *bch2_fs_usage_read(struct bch_fs *c)
+{
+       struct bch_fs_usage_online *ret;
+       unsigned nr_replicas = READ_ONCE(c->replicas.nr);
+       unsigned seq, i;
+retry:
+       ret = kmalloc(__fs_usage_online_u64s(nr_replicas) * sizeof(u64), GFP_KERNEL);
+       if (unlikely(!ret))
+               return NULL;
+
+       percpu_down_read(&c->mark_lock);
+
+       if (nr_replicas != c->replicas.nr) {
+               nr_replicas = c->replicas.nr;
+               percpu_up_read(&c->mark_lock);
+               kfree(ret);
+               goto retry;
+       }
 
-static void bch2_fs_stats_verify(struct bch_fs *c) {}
-static void bch2_dev_stats_verify(struct bch_dev *ca) {}
-static void bch2_disk_reservations_verify(struct bch_fs *c, int flags) {}
+       ret->online_reserved = percpu_u64_get(c->online_reserved);
 
-#endif
+       do {
+               seq = read_seqcount_begin(&c->usage_lock);
+               unsafe_memcpy(&ret->u, c->usage_base,
+                             __fs_usage_u64s(nr_replicas) * sizeof(u64),
+                             "embedded variable length struct");
+               for (i = 0; i < ARRAY_SIZE(c->usage); i++)
+                       acc_u64s_percpu((u64 *) &ret->u, (u64 __percpu *) c->usage[i],
+                                       __fs_usage_u64s(nr_replicas));
+       } while (read_seqcount_retry(&c->usage_lock, seq));
 
-/*
- * Clear journal_seq_valid for buckets for which it's not needed, to prevent
- * wraparound:
- */
-void bch2_bucket_seq_cleanup(struct bch_fs *c)
+       return ret;
+}
+
+void bch2_fs_usage_acc_to_base(struct bch_fs *c, unsigned idx)
 {
-       u16 last_seq_ondisk = c->journal.last_seq_ondisk;
        struct bch_dev *ca;
-       struct bucket_array *buckets;
-       struct bucket *g;
-       struct bucket_mark m;
-       unsigned i;
+       unsigned i, u64s = fs_usage_u64s(c);
 
-       for_each_member_device(ca, c, i) {
-               down_read(&ca->bucket_lock);
-               buckets = bucket_array(ca);
+       BUG_ON(idx >= ARRAY_SIZE(c->usage));
 
-               for_each_bucket(g, buckets) {
-                       bucket_cmpxchg(g, m, ({
-                               if (!m.journal_seq_valid ||
-                                   bucket_needs_journal_commit(m, last_seq_ondisk))
-                                       break;
+       preempt_disable();
+       write_seqcount_begin(&c->usage_lock);
 
-                               m.journal_seq_valid = 0;
-                       }));
-               }
-               up_read(&ca->bucket_lock);
+       acc_u64s_percpu((u64 *) c->usage_base,
+                       (u64 __percpu *) c->usage[idx], u64s);
+       percpu_memset(c->usage[idx], 0, u64s * sizeof(u64));
+
+       rcu_read_lock();
+       for_each_member_device_rcu(ca, c, i, NULL) {
+               u64s = dev_usage_u64s();
+
+               acc_u64s_percpu((u64 *) ca->usage_base,
+                               (u64 __percpu *) ca->usage[idx], u64s);
+               percpu_memset(ca->usage[idx], 0, u64s * sizeof(u64));
        }
+       rcu_read_unlock();
+
+       write_seqcount_end(&c->usage_lock);
+       preempt_enable();
 }
 
-#define bch2_usage_add(_acc, _stats)                                   \
-do {                                                                   \
-       typeof(_acc) _a = (_acc), _s = (_stats);                        \
-       unsigned i;                                                     \
-                                                                       \
-       for (i = 0; i < sizeof(*_a) / sizeof(u64); i++)                 \
-               ((u64 *) (_a))[i] += ((u64 *) (_s))[i];                 \
-} while (0)
+void bch2_fs_usage_to_text(struct printbuf *out,
+                          struct bch_fs *c,
+                          struct bch_fs_usage_online *fs_usage)
+{
+       unsigned i;
 
-#define bch2_usage_read_raw(_stats)                                    \
-({                                                                     \
-       typeof(*this_cpu_ptr(_stats)) _acc;                             \
-       int cpu;                                                        \
-                                                                       \
-       memset(&_acc, 0, sizeof(_acc));                                 \
-                                                                       \
-       for_each_possible_cpu(cpu)                                      \
-               bch2_usage_add(&_acc, per_cpu_ptr((_stats), cpu));      \
-                                                                       \
-       _acc;                                                           \
-})
+       prt_printf(out, "capacity:\t\t\t%llu\n", c->capacity);
+
+       prt_printf(out, "hidden:\t\t\t\t%llu\n",
+              fs_usage->u.hidden);
+       prt_printf(out, "data:\t\t\t\t%llu\n",
+              fs_usage->u.data);
+       prt_printf(out, "cached:\t\t\t\t%llu\n",
+              fs_usage->u.cached);
+       prt_printf(out, "reserved:\t\t\t%llu\n",
+              fs_usage->u.reserved);
+       prt_printf(out, "nr_inodes:\t\t\t%llu\n",
+              fs_usage->u.nr_inodes);
+       prt_printf(out, "online reserved:\t\t%llu\n",
+              fs_usage->online_reserved);
+
+       for (i = 0;
+            i < ARRAY_SIZE(fs_usage->u.persistent_reserved);
+            i++) {
+               prt_printf(out, "%u replicas:\n", i + 1);
+               prt_printf(out, "\treserved:\t\t%llu\n",
+                      fs_usage->u.persistent_reserved[i]);
+       }
+
+       for (i = 0; i < c->replicas.nr; i++) {
+               struct bch_replicas_entry *e =
+                       cpu_replicas_entry(&c->replicas, i);
+
+               prt_printf(out, "\t");
+               bch2_replicas_entry_to_text(out, e);
+               prt_printf(out, ":\t%llu\n", fs_usage->u.replicas[i]);
+       }
+}
 
-#define bch2_usage_read_cached(_c, _cached, _uncached)                 \
-({                                                                     \
-       typeof(_cached) _ret;                                           \
-       unsigned _seq;                                                  \
-                                                                       \
-       do {                                                            \
-               _seq = read_seqcount_begin(&(_c)->gc_pos_lock);         \
-               _ret = (_c)->gc_pos.phase == GC_PHASE_DONE              \
-                       ? bch2_usage_read_raw(_uncached)                        \
-                       : (_cached);                                    \
-       } while (read_seqcount_retry(&(_c)->gc_pos_lock, _seq));        \
-                                                                       \
-       _ret;                                                           \
-})
+static u64 reserve_factor(u64 r)
+{
+       return r + (round_up(r, (1 << RESERVE_FACTOR)) >> RESERVE_FACTOR);
+}
 
-struct bch_dev_usage __bch2_dev_usage_read(struct bch_dev *ca)
+u64 bch2_fs_sectors_used(struct bch_fs *c, struct bch_fs_usage_online *fs_usage)
 {
-       return bch2_usage_read_raw(ca->usage_percpu);
+       return min(fs_usage->u.hidden +
+                  fs_usage->u.btree +
+                  fs_usage->u.data +
+                  reserve_factor(fs_usage->u.reserved +
+                                 fs_usage->online_reserved),
+                  c->capacity);
 }
 
-struct bch_dev_usage bch2_dev_usage_read(struct bch_fs *c, struct bch_dev *ca)
+static struct bch_fs_usage_short
+__bch2_fs_usage_read_short(struct bch_fs *c)
 {
-       return bch2_usage_read_cached(c, ca->usage_cached, ca->usage_percpu);
+       struct bch_fs_usage_short ret;
+       u64 data, reserved;
+
+       ret.capacity = c->capacity -
+               bch2_fs_usage_read_one(c, &c->usage_base->hidden);
+
+       data            = bch2_fs_usage_read_one(c, &c->usage_base->data) +
+               bch2_fs_usage_read_one(c, &c->usage_base->btree);
+       reserved        = bch2_fs_usage_read_one(c, &c->usage_base->reserved) +
+               percpu_u64_get(c->online_reserved);
+
+       ret.used        = min(ret.capacity, data + reserve_factor(reserved));
+       ret.free        = ret.capacity - ret.used;
+
+       ret.nr_inodes   = bch2_fs_usage_read_one(c, &c->usage_base->nr_inodes);
+
+       return ret;
 }
 
-struct bch_fs_usage
-__bch2_fs_usage_read(struct bch_fs *c)
+struct bch_fs_usage_short
+bch2_fs_usage_read_short(struct bch_fs *c)
 {
-       return bch2_usage_read_raw(c->usage_percpu);
+       struct bch_fs_usage_short ret;
+
+       percpu_down_read(&c->mark_lock);
+       ret = __bch2_fs_usage_read_short(c);
+       percpu_up_read(&c->mark_lock);
+
+       return ret;
 }
 
-struct bch_fs_usage
-bch2_fs_usage_read(struct bch_fs *c)
+void bch2_dev_usage_init(struct bch_dev *ca)
 {
-       return bch2_usage_read_cached(c,
-                                    c->usage_cached,
-                                    c->usage_percpu);
+       ca->usage_base->d[BCH_DATA_free].buckets = ca->mi.nbuckets - ca->mi.first_bucket;
 }
 
-struct fs_usage_sum {
-       u64     data;
-       u64     reserved;
-};
+static inline int bucket_sectors_fragmented(struct bch_dev *ca,
+                                           struct bch_alloc_v4 a)
+{
+       return a.dirty_sectors
+               ? max(0, (int) ca->mi.bucket_size - (int) a.dirty_sectors)
+               : 0;
+}
 
-static inline struct fs_usage_sum __fs_usage_sum(struct bch_fs_usage stats)
+static void bch2_dev_usage_update(struct bch_fs *c, struct bch_dev *ca,
+                                 struct bch_alloc_v4 old,
+                                 struct bch_alloc_v4 new,
+                                 u64 journal_seq, bool gc)
 {
-       struct fs_usage_sum sum = { 0 };
-       unsigned i;
+       struct bch_fs_usage *fs_usage;
+       struct bch_dev_usage *u;
 
-       for (i = 0; i < ARRAY_SIZE(stats.s); i++) {
-               sum.data += (stats.s[i].data[S_META] +
-                            stats.s[i].data[S_DIRTY]) * (i + 1);
-               sum.reserved += stats.s[i].persistent_reserved * (i + 1);
-       }
+       preempt_disable();
+       fs_usage = fs_usage_ptr(c, journal_seq, gc);
 
-       sum.reserved += stats.online_reserved;
-       return sum;
-}
+       if (data_type_is_hidden(old.data_type))
+               fs_usage->hidden -= ca->mi.bucket_size;
+       if (data_type_is_hidden(new.data_type))
+               fs_usage->hidden += ca->mi.bucket_size;
 
-#define RESERVE_FACTOR 6
+       u = dev_usage_ptr(ca, journal_seq, gc);
 
-static u64 reserve_factor(u64 r)
+       u->d[old.data_type].buckets--;
+       u->d[new.data_type].buckets++;
+
+       u->buckets_ec -= (int) !!old.stripe;
+       u->buckets_ec += (int) !!new.stripe;
+
+       u->d[old.data_type].sectors -= old.dirty_sectors;
+       u->d[new.data_type].sectors += new.dirty_sectors;
+
+       u->d[BCH_DATA_cached].sectors += new.cached_sectors;
+       u->d[BCH_DATA_cached].sectors -= old.cached_sectors;
+
+       u->d[old.data_type].fragmented -= bucket_sectors_fragmented(ca, old);
+       u->d[new.data_type].fragmented += bucket_sectors_fragmented(ca, new);
+
+       preempt_enable();
+}
+
+static void bch2_dev_usage_update_m(struct bch_fs *c, struct bch_dev *ca,
+                                   struct bucket old, struct bucket new,
+                                   u64 journal_seq, bool gc)
 {
-       return r + (round_up(r, (1 << RESERVE_FACTOR)) >> RESERVE_FACTOR);
+       struct bch_alloc_v4 old_a = {
+               .gen            = old.gen,
+               .data_type      = old.data_type,
+               .dirty_sectors  = old.dirty_sectors,
+               .cached_sectors = old.cached_sectors,
+               .stripe         = old.stripe,
+       };
+       struct bch_alloc_v4 new_a = {
+               .gen            = new.gen,
+               .data_type      = new.data_type,
+               .dirty_sectors  = new.dirty_sectors,
+               .cached_sectors = new.cached_sectors,
+               .stripe         = new.stripe,
+       };
+
+       bch2_dev_usage_update(c, ca, old_a, new_a, journal_seq, gc);
 }
 
-static u64 avail_factor(u64 r)
+static inline int __update_replicas(struct bch_fs *c,
+                                   struct bch_fs_usage *fs_usage,
+                                   struct bch_replicas_entry *r,
+                                   s64 sectors)
 {
-       return (r << RESERVE_FACTOR) / (1 << RESERVE_FACTOR) + 1;
+       int idx = bch2_replicas_entry_idx(c, r);
+
+       if (idx < 0)
+               return -1;
+
+       fs_usage_data_type_to_base(fs_usage, r->data_type, sectors);
+       fs_usage->replicas[idx]         += sectors;
+       return 0;
 }
 
-u64 __bch2_fs_sectors_used(struct bch_fs *c, struct bch_fs_usage stats)
+static inline int update_replicas(struct bch_fs *c, struct bkey_s_c k,
+                       struct bch_replicas_entry *r, s64 sectors,
+                       unsigned journal_seq, bool gc)
 {
-       struct fs_usage_sum sum = __fs_usage_sum(stats);
+       struct bch_fs_usage *fs_usage;
+       int idx, ret = 0;
+       struct printbuf buf = PRINTBUF;
+
+       percpu_down_read(&c->mark_lock);
+
+       idx = bch2_replicas_entry_idx(c, r);
+       if (idx < 0 &&
+           fsck_err(c, ptr_to_missing_replicas_entry,
+                    "no replicas entry\n  while marking %s",
+                    (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
+               percpu_up_read(&c->mark_lock);
+               ret = bch2_mark_replicas(c, r);
+               percpu_down_read(&c->mark_lock);
+
+               if (ret)
+                       goto err;
+               idx = bch2_replicas_entry_idx(c, r);
+       }
+       if (idx < 0) {
+               ret = -1;
+               goto err;
+       }
 
-       return sum.data + reserve_factor(sum.reserved);
+       preempt_disable();
+       fs_usage = fs_usage_ptr(c, journal_seq, gc);
+       fs_usage_data_type_to_base(fs_usage, r->data_type, sectors);
+       fs_usage->replicas[idx]         += sectors;
+       preempt_enable();
+err:
+fsck_err:
+       percpu_up_read(&c->mark_lock);
+       printbuf_exit(&buf);
+       return ret;
 }
 
-u64 bch2_fs_sectors_used(struct bch_fs *c, struct bch_fs_usage stats)
+static inline int update_cached_sectors(struct bch_fs *c,
+                       struct bkey_s_c k,
+                       unsigned dev, s64 sectors,
+                       unsigned journal_seq, bool gc)
 {
-       return min(c->capacity, __bch2_fs_sectors_used(c, stats));
+       struct bch_replicas_padded r;
+
+       bch2_replicas_entry_cached(&r.e, dev);
+
+       return update_replicas(c, k, &r.e, sectors, journal_seq, gc);
 }
 
-u64 bch2_fs_sectors_free(struct bch_fs *c, struct bch_fs_usage stats)
+static int __replicas_deltas_realloc(struct btree_trans *trans, unsigned more,
+                                    gfp_t gfp)
 {
-       return avail_factor(c->capacity - bch2_fs_sectors_used(c, stats));
+       struct replicas_delta_list *d = trans->fs_usage_deltas;
+       unsigned new_size = d ? (d->size + more) * 2 : 128;
+       unsigned alloc_size = sizeof(*d) + new_size;
+
+       WARN_ON_ONCE(alloc_size > REPLICAS_DELTA_LIST_MAX);
+
+       if (!d || d->used + more > d->size) {
+               d = krealloc(d, alloc_size, gfp|__GFP_ZERO);
+
+               if (unlikely(!d)) {
+                       if (alloc_size > REPLICAS_DELTA_LIST_MAX)
+                               return -ENOMEM;
+
+                       d = mempool_alloc(&trans->c->replicas_delta_pool, gfp);
+                       if (!d)
+                               return -ENOMEM;
+
+                       memset(d, 0, REPLICAS_DELTA_LIST_MAX);
+
+                       if (trans->fs_usage_deltas)
+                               memcpy(d, trans->fs_usage_deltas,
+                                      trans->fs_usage_deltas->size + sizeof(*d));
+
+                       new_size = REPLICAS_DELTA_LIST_MAX - sizeof(*d);
+                       kfree(trans->fs_usage_deltas);
+               }
+
+               d->size = new_size;
+               trans->fs_usage_deltas = d;
+       }
+
+       return 0;
 }
 
-static inline int is_unavailable_bucket(struct bucket_mark m)
+int bch2_replicas_deltas_realloc(struct btree_trans *trans, unsigned more)
 {
-       return !is_available_bucket(m);
+       return allocate_dropping_locks_errcode(trans,
+                               __replicas_deltas_realloc(trans, more, _gfp));
 }
 
-static inline int is_fragmented_bucket(struct bucket_mark m,
-                                      struct bch_dev *ca)
+static inline int update_replicas_list(struct btree_trans *trans,
+                                       struct bch_replicas_entry *r,
+                                       s64 sectors)
 {
-       if (!m.owned_by_allocator &&
-           m.data_type == BCH_DATA_USER &&
-           bucket_sectors_used(m))
-               return max_t(int, 0, (int) ca->mi.bucket_size -
-                            bucket_sectors_used(m));
+       struct replicas_delta_list *d;
+       struct replicas_delta *n;
+       unsigned b;
+       int ret;
+
+       if (!sectors)
+               return 0;
+
+       b = replicas_entry_bytes(r) + 8;
+       ret = bch2_replicas_deltas_realloc(trans, b);
+       if (ret)
+               return ret;
+
+       d = trans->fs_usage_deltas;
+       n = (void *) d->d + d->used;
+       n->delta = sectors;
+       unsafe_memcpy((void *) n + offsetof(struct replicas_delta, r),
+                     r, replicas_entry_bytes(r),
+                     "flexible array member embedded in strcuct with padding");
+       bch2_replicas_entry_sort(&n->r);
+       d->used += b;
        return 0;
 }
 
-static inline enum bch_data_type bucket_type(struct bucket_mark m)
+static inline int update_cached_sectors_list(struct btree_trans *trans,
+                                             unsigned dev, s64 sectors)
 {
-       return m.cached_sectors && !m.dirty_sectors
-               ?  BCH_DATA_CACHED
-               : m.data_type;
+       struct bch_replicas_padded r;
+
+       bch2_replicas_entry_cached(&r.e, dev);
+
+       return update_replicas_list(trans, &r.e, sectors);
 }
 
-static bool bucket_became_unavailable(struct bch_fs *c,
-                                     struct bucket_mark old,
-                                     struct bucket_mark new)
+int bch2_mark_alloc(struct btree_trans *trans,
+                   enum btree_id btree, unsigned level,
+                   struct bkey_s_c old, struct bkey_s_c new,
+                   unsigned flags)
 {
-       return is_available_bucket(old) &&
-              !is_available_bucket(new) &&
-              (!c || c->gc_pos.phase == GC_PHASE_DONE);
+       bool gc = flags & BTREE_TRIGGER_GC;
+       u64 journal_seq = trans->journal_res.seq;
+       u64 bucket_journal_seq;
+       struct bch_fs *c = trans->c;
+       struct bch_alloc_v4 old_a_convert, new_a_convert;
+       const struct bch_alloc_v4 *old_a, *new_a;
+       struct bch_dev *ca;
+       int ret = 0;
+
+       /*
+        * alloc btree is read in by bch2_alloc_read, not gc:
+        */
+       if ((flags & BTREE_TRIGGER_GC) &&
+           !(flags & BTREE_TRIGGER_BUCKET_INVALIDATE))
+               return 0;
+
+       if (bch2_trans_inconsistent_on(!bch2_dev_bucket_exists(c, new.k->p), trans,
+                                      "alloc key for invalid device or bucket"))
+               return -EIO;
+
+       ca = bch_dev_bkey_exists(c, new.k->p.inode);
+
+       old_a = bch2_alloc_to_v4(old, &old_a_convert);
+       new_a = bch2_alloc_to_v4(new, &new_a_convert);
+
+       bucket_journal_seq = new_a->journal_seq;
+
+       if ((flags & BTREE_TRIGGER_INSERT) &&
+           data_type_is_empty(old_a->data_type) !=
+           data_type_is_empty(new_a->data_type) &&
+           new.k->type == KEY_TYPE_alloc_v4) {
+               struct bch_alloc_v4 *v = (struct bch_alloc_v4 *) new.v;
+
+               EBUG_ON(!journal_seq);
+
+               /*
+                * If the btree updates referring to a bucket weren't flushed
+                * before the bucket became empty again, then the we don't have
+                * to wait on a journal flush before we can reuse the bucket:
+                */
+               v->journal_seq = bucket_journal_seq =
+                       data_type_is_empty(new_a->data_type) &&
+                       (journal_seq == v->journal_seq ||
+                        bch2_journal_noflush_seq(&c->journal, v->journal_seq))
+                       ? 0 : journal_seq;
+       }
+
+       if (!data_type_is_empty(old_a->data_type) &&
+           data_type_is_empty(new_a->data_type) &&
+           bucket_journal_seq) {
+               ret = bch2_set_bucket_needs_journal_commit(&c->buckets_waiting_for_journal,
+                               c->journal.flushed_seq_ondisk,
+                               new.k->p.inode, new.k->p.offset,
+                               bucket_journal_seq);
+               if (ret) {
+                       bch2_fs_fatal_error(c,
+                               "error setting bucket_needs_journal_commit: %i", ret);
+                       return ret;
+               }
+       }
+
+       percpu_down_read(&c->mark_lock);
+       if (!gc && new_a->gen != old_a->gen)
+               *bucket_gen(ca, new.k->p.offset) = new_a->gen;
+
+       bch2_dev_usage_update(c, ca, *old_a, *new_a, journal_seq, gc);
+
+       if (gc) {
+               struct bucket *g = gc_bucket(ca, new.k->p.offset);
+
+               bucket_lock(g);
+
+               g->gen_valid            = 1;
+               g->gen                  = new_a->gen;
+               g->data_type            = new_a->data_type;
+               g->stripe               = new_a->stripe;
+               g->stripe_redundancy    = new_a->stripe_redundancy;
+               g->dirty_sectors        = new_a->dirty_sectors;
+               g->cached_sectors       = new_a->cached_sectors;
+
+               bucket_unlock(g);
+       }
+       percpu_up_read(&c->mark_lock);
+
+       /*
+        * need to know if we're getting called from the invalidate path or
+        * not:
+        */
+
+       if ((flags & BTREE_TRIGGER_BUCKET_INVALIDATE) &&
+           old_a->cached_sectors) {
+               ret = update_cached_sectors(c, new, ca->dev_idx,
+                                           -((s64) old_a->cached_sectors),
+                                           journal_seq, gc);
+               if (ret) {
+                       bch2_fs_fatal_error(c, "%s(): no replicas entry while updating cached sectors",
+                                           __func__);
+                       return ret;
+               }
+       }
+
+       if (new_a->data_type == BCH_DATA_free &&
+           (!new_a->journal_seq || new_a->journal_seq < c->journal.flushed_seq_ondisk))
+               closure_wake_up(&c->freelist_wait);
+
+       if (new_a->data_type == BCH_DATA_need_discard &&
+           (!bucket_journal_seq || bucket_journal_seq < c->journal.flushed_seq_ondisk))
+               bch2_do_discards(c);
+
+       if (old_a->data_type != BCH_DATA_cached &&
+           new_a->data_type == BCH_DATA_cached &&
+           should_invalidate_buckets(ca, bch2_dev_usage_read(ca)))
+               bch2_do_invalidates(c);
+
+       if (new_a->data_type == BCH_DATA_need_gc_gens)
+               bch2_do_gc_gens(c);
+
+       return 0;
 }
 
-void bch2_fs_usage_apply(struct bch_fs *c,
-                       struct bch_fs_usage *stats,
-                       struct disk_reservation *disk_res,
-                       struct gc_pos gc_pos)
+int bch2_mark_metadata_bucket(struct bch_fs *c, struct bch_dev *ca,
+                             size_t b, enum bch_data_type data_type,
+                             unsigned sectors, struct gc_pos pos,
+                             unsigned flags)
 {
-       struct fs_usage_sum sum = __fs_usage_sum(*stats);
-       s64 added = sum.data + sum.reserved;
+       struct bucket old, new, *g;
+       int ret = 0;
+
+       BUG_ON(!(flags & BTREE_TRIGGER_GC));
+       BUG_ON(data_type != BCH_DATA_sb &&
+              data_type != BCH_DATA_journal);
 
        /*
-        * Not allowed to reduce sectors_available except by getting a
-        * reservation:
+        * Backup superblock might be past the end of our normal usable space:
         */
-       BUG_ON(added > (s64) (disk_res ? disk_res->sectors : 0));
+       if (b >= ca->mi.nbuckets)
+               return 0;
 
-       if (added > 0) {
-               disk_res->sectors       -= added;
-               stats->online_reserved  -= added;
+       percpu_down_read(&c->mark_lock);
+       g = gc_bucket(ca, b);
+
+       bucket_lock(g);
+       old = *g;
+
+       if (bch2_fs_inconsistent_on(g->data_type &&
+                       g->data_type != data_type, c,
+                       "different types of data in same bucket: %s, %s",
+                       bch2_data_types[g->data_type],
+                       bch2_data_types[data_type])) {
+               ret = -EIO;
+               goto err;
+       }
+
+       if (bch2_fs_inconsistent_on((u64) g->dirty_sectors + sectors > ca->mi.bucket_size, c,
+                       "bucket %u:%zu gen %u data type %s sector count overflow: %u + %u > bucket size",
+                       ca->dev_idx, b, g->gen,
+                       bch2_data_types[g->data_type ?: data_type],
+                       g->dirty_sectors, sectors)) {
+               ret = -EIO;
+               goto err;
        }
 
-       percpu_down_read_preempt_disable(&c->usage_lock);
-       /* online_reserved not subject to gc: */
-       this_cpu_ptr(c->usage_percpu)->online_reserved +=
-               stats->online_reserved;
-       stats->online_reserved = 0;
 
-       if (!gc_will_visit(c, gc_pos))
-               bch2_usage_add(this_cpu_ptr(c->usage_percpu), stats);
+       g->data_type = data_type;
+       g->dirty_sectors += sectors;
+       new = *g;
+err:
+       bucket_unlock(g);
+       if (!ret)
+               bch2_dev_usage_update_m(c, ca, old, new, 0, true);
+       percpu_up_read(&c->mark_lock);
+       return ret;
+}
 
-       bch2_fs_stats_verify(c);
-       percpu_up_read_preempt_enable(&c->usage_lock);
+static int check_bucket_ref(struct btree_trans *trans,
+                           struct bkey_s_c k,
+                           const struct bch_extent_ptr *ptr,
+                           s64 sectors, enum bch_data_type ptr_data_type,
+                           u8 b_gen, u8 bucket_data_type,
+                           u32 dirty_sectors, u32 cached_sectors)
+{
+       struct bch_fs *c = trans->c;
+       struct bch_dev *ca = bch_dev_bkey_exists(c, ptr->dev);
+       size_t bucket_nr = PTR_BUCKET_NR(ca, ptr);
+       u32 bucket_sectors = !ptr->cached
+               ? dirty_sectors
+               : cached_sectors;
+       struct printbuf buf = PRINTBUF;
+       int ret = 0;
+
+       if (bucket_data_type == BCH_DATA_cached)
+               bucket_data_type = BCH_DATA_user;
+
+       if ((bucket_data_type == BCH_DATA_stripe && ptr_data_type == BCH_DATA_user) ||
+           (bucket_data_type == BCH_DATA_user   && ptr_data_type == BCH_DATA_stripe))
+               bucket_data_type = ptr_data_type = BCH_DATA_stripe;
+
+       if (gen_after(ptr->gen, b_gen)) {
+               bch2_fsck_err(c, FSCK_CAN_IGNORE|FSCK_NEED_FSCK,
+                             BCH_FSCK_ERR_ptr_gen_newer_than_bucket_gen,
+                       "bucket %u:%zu gen %u data type %s: ptr gen %u newer than bucket gen\n"
+                       "while marking %s",
+                       ptr->dev, bucket_nr, b_gen,
+                       bch2_data_types[bucket_data_type ?: ptr_data_type],
+                       ptr->gen,
+                       (bch2_bkey_val_to_text(&buf, c, k), buf.buf));
+               ret = -EIO;
+               goto err;
+       }
+
+       if (gen_cmp(b_gen, ptr->gen) > BUCKET_GC_GEN_MAX) {
+               bch2_fsck_err(c, FSCK_CAN_IGNORE|FSCK_NEED_FSCK,
+                             BCH_FSCK_ERR_ptr_too_stale,
+                       "bucket %u:%zu gen %u data type %s: ptr gen %u too stale\n"
+                       "while marking %s",
+                       ptr->dev, bucket_nr, b_gen,
+                       bch2_data_types[bucket_data_type ?: ptr_data_type],
+                       ptr->gen,
+                       (printbuf_reset(&buf),
+                        bch2_bkey_val_to_text(&buf, c, k), buf.buf));
+               ret = -EIO;
+               goto err;
+       }
+
+       if (b_gen != ptr->gen && !ptr->cached) {
+               bch2_fsck_err(c, FSCK_CAN_IGNORE|FSCK_NEED_FSCK,
+                             BCH_FSCK_ERR_stale_dirty_ptr,
+                       "bucket %u:%zu gen %u (mem gen %u) data type %s: stale dirty ptr (gen %u)\n"
+                       "while marking %s",
+                       ptr->dev, bucket_nr, b_gen,
+                       *bucket_gen(ca, bucket_nr),
+                       bch2_data_types[bucket_data_type ?: ptr_data_type],
+                       ptr->gen,
+                       (printbuf_reset(&buf),
+                        bch2_bkey_val_to_text(&buf, c, k), buf.buf));
+               ret = -EIO;
+               goto err;
+       }
+
+       if (b_gen != ptr->gen) {
+               ret = 1;
+               goto out;
+       }
+
+       if (!data_type_is_empty(bucket_data_type) &&
+           ptr_data_type &&
+           bucket_data_type != ptr_data_type) {
+               bch2_fsck_err(c, FSCK_CAN_IGNORE|FSCK_NEED_FSCK,
+                             BCH_FSCK_ERR_ptr_bucket_data_type_mismatch,
+                       "bucket %u:%zu gen %u different types of data in same bucket: %s, %s\n"
+                       "while marking %s",
+                       ptr->dev, bucket_nr, b_gen,
+                       bch2_data_types[bucket_data_type],
+                       bch2_data_types[ptr_data_type],
+                       (printbuf_reset(&buf),
+                        bch2_bkey_val_to_text(&buf, c, k), buf.buf));
+               ret = -EIO;
+               goto err;
+       }
 
-       memset(stats, 0, sizeof(*stats));
+       if ((u64) bucket_sectors + sectors > U32_MAX) {
+               bch2_fsck_err(c, FSCK_CAN_IGNORE|FSCK_NEED_FSCK,
+                             BCH_FSCK_ERR_bucket_sector_count_overflow,
+                       "bucket %u:%zu gen %u data type %s sector count overflow: %u + %lli > U32_MAX\n"
+                       "while marking %s",
+                       ptr->dev, bucket_nr, b_gen,
+                       bch2_data_types[bucket_data_type ?: ptr_data_type],
+                       bucket_sectors, sectors,
+                       (printbuf_reset(&buf),
+                        bch2_bkey_val_to_text(&buf, c, k), buf.buf));
+               ret = -EIO;
+               goto err;
+       }
+out:
+       printbuf_exit(&buf);
+       return ret;
+err:
+       bch2_dump_trans_updates(trans);
+       goto out;
 }
 
-static void bch2_dev_usage_update(struct bch_fs *c, struct bch_dev *ca,
-                                 struct bucket_mark old, struct bucket_mark new)
+static int mark_stripe_bucket(struct btree_trans *trans,
+                             struct bkey_s_c k,
+                             unsigned ptr_idx,
+                             unsigned flags)
 {
-       struct bch_dev_usage *dev_usage;
+       struct bch_fs *c = trans->c;
+       u64 journal_seq = trans->journal_res.seq;
+       const struct bch_stripe *s = bkey_s_c_to_stripe(k).v;
+       unsigned nr_data = s->nr_blocks - s->nr_redundant;
+       bool parity = ptr_idx >= nr_data;
+       enum bch_data_type data_type = parity ? BCH_DATA_parity : BCH_DATA_stripe;
+       s64 sectors = parity ? le16_to_cpu(s->sectors) : 0;
+       const struct bch_extent_ptr *ptr = s->ptrs + ptr_idx;
+       struct bch_dev *ca = bch_dev_bkey_exists(c, ptr->dev);
+       struct bucket old, new, *g;
+       struct printbuf buf = PRINTBUF;
+       int ret = 0;
+
+       BUG_ON(!(flags & BTREE_TRIGGER_GC));
 
-       if (c)
-               percpu_rwsem_assert_held(&c->usage_lock);
+       /* * XXX doesn't handle deletion */
 
-       if (old.data_type && new.data_type &&
-           old.data_type != new.data_type) {
-               BUG_ON(!c);
+       percpu_down_read(&c->mark_lock);
+       g = PTR_GC_BUCKET(ca, ptr);
+
+       if (g->dirty_sectors ||
+           (g->stripe && g->stripe != k.k->p.offset)) {
                bch2_fs_inconsistent(c,
-                       "different types of data in same bucket: %s, %s",
-                       bch2_data_types[old.data_type],
-                       bch2_data_types[new.data_type]);
+                             "bucket %u:%zu gen %u: multiple stripes using same bucket\n%s",
+                             ptr->dev, PTR_BUCKET_NR(ca, ptr), g->gen,
+                             (bch2_bkey_val_to_text(&buf, c, k), buf.buf));
+               ret = -EINVAL;
+               goto err;
        }
 
-       dev_usage = this_cpu_ptr(ca->usage_percpu);
+       bucket_lock(g);
+       old = *g;
+
+       ret = check_bucket_ref(trans, k, ptr, sectors, data_type,
+                              g->gen, g->data_type,
+                              g->dirty_sectors, g->cached_sectors);
+       if (ret)
+               goto err;
 
-       dev_usage->buckets[bucket_type(old)]--;
-       dev_usage->buckets[bucket_type(new)]++;
+       g->data_type = data_type;
+       g->dirty_sectors += sectors;
 
-       dev_usage->buckets_alloc +=
-               (int) new.owned_by_allocator - (int) old.owned_by_allocator;
-       dev_usage->buckets_unavailable +=
-               is_unavailable_bucket(new) - is_unavailable_bucket(old);
+       g->stripe               = k.k->p.offset;
+       g->stripe_redundancy    = s->nr_redundant;
+       new = *g;
+err:
+       bucket_unlock(g);
+       if (!ret)
+               bch2_dev_usage_update_m(c, ca, old, new, journal_seq, true);
+       percpu_up_read(&c->mark_lock);
+       printbuf_exit(&buf);
+       return ret;
+}
 
-       dev_usage->sectors[old.data_type] -= old.dirty_sectors;
-       dev_usage->sectors[new.data_type] += new.dirty_sectors;
-       dev_usage->sectors[BCH_DATA_CACHED] +=
-               (int) new.cached_sectors - (int) old.cached_sectors;
-       dev_usage->sectors_fragmented +=
-               is_fragmented_bucket(new, ca) - is_fragmented_bucket(old, ca);
+static int __mark_pointer(struct btree_trans *trans,
+                         struct bkey_s_c k,
+                         const struct bch_extent_ptr *ptr,
+                         s64 sectors, enum bch_data_type ptr_data_type,
+                         u8 bucket_gen, u8 *bucket_data_type,
+                         u32 *dirty_sectors, u32 *cached_sectors)
+{
+       u32 *dst_sectors = !ptr->cached
+               ? dirty_sectors
+               : cached_sectors;
+       int ret = check_bucket_ref(trans, k, ptr, sectors, ptr_data_type,
+                                  bucket_gen, *bucket_data_type,
+                                  *dirty_sectors, *cached_sectors);
+
+       if (ret)
+               return ret;
+
+       *dst_sectors += sectors;
+       *bucket_data_type = *dirty_sectors || *cached_sectors
+               ? ptr_data_type : 0;
+       return 0;
+}
 
-       if (!is_available_bucket(old) && is_available_bucket(new))
-               bch2_wake_allocator(ca);
+static int bch2_mark_pointer(struct btree_trans *trans,
+                            enum btree_id btree_id, unsigned level,
+                            struct bkey_s_c k,
+                            struct extent_ptr_decoded p,
+                            s64 sectors,
+                            unsigned flags)
+{
+       u64 journal_seq = trans->journal_res.seq;
+       struct bch_fs *c = trans->c;
+       struct bch_dev *ca = bch_dev_bkey_exists(c, p.ptr.dev);
+       struct bucket old, new, *g;
+       enum bch_data_type data_type = bkey_ptr_data_type(btree_id, level, k, p);
+       u8 bucket_data_type;
+       int ret = 0;
+
+       BUG_ON(!(flags & BTREE_TRIGGER_GC));
+
+       percpu_down_read(&c->mark_lock);
+       g = PTR_GC_BUCKET(ca, &p.ptr);
+       bucket_lock(g);
+       old = *g;
+
+       bucket_data_type = g->data_type;
+       ret = __mark_pointer(trans, k, &p.ptr, sectors,
+                            data_type, g->gen,
+                            &bucket_data_type,
+                            &g->dirty_sectors,
+                            &g->cached_sectors);
+       if (!ret)
+               g->data_type = bucket_data_type;
+
+       new = *g;
+       bucket_unlock(g);
+       if (!ret)
+               bch2_dev_usage_update_m(c, ca, old, new, journal_seq, true);
+       percpu_up_read(&c->mark_lock);
 
-       bch2_dev_stats_verify(ca);
+       return ret;
 }
 
-#define bucket_data_cmpxchg(c, ca, g, new, expr)               \
-({                                                             \
-       struct bucket_mark _old = bucket_cmpxchg(g, new, expr); \
-                                                               \
-       bch2_dev_usage_update(c, ca, _old, new);                \
-       _old;                                                   \
-})
+static int bch2_mark_stripe_ptr(struct btree_trans *trans,
+                               struct bkey_s_c k,
+                               struct bch_extent_stripe_ptr p,
+                               enum bch_data_type data_type,
+                               s64 sectors,
+                               unsigned flags)
+{
+       struct bch_fs *c = trans->c;
+       struct bch_replicas_padded r;
+       struct gc_stripe *m;
+
+       BUG_ON(!(flags & BTREE_TRIGGER_GC));
+
+       m = genradix_ptr_alloc(&c->gc_stripes, p.idx, GFP_KERNEL);
+       if (!m) {
+               bch_err(c, "error allocating memory for gc_stripes, idx %llu",
+                       (u64) p.idx);
+               return -BCH_ERR_ENOMEM_mark_stripe_ptr;
+       }
+
+       mutex_lock(&c->ec_stripes_heap_lock);
+
+       if (!m || !m->alive) {
+               mutex_unlock(&c->ec_stripes_heap_lock);
+               bch_err_ratelimited(c, "pointer to nonexistent stripe %llu",
+                                   (u64) p.idx);
+               bch2_inconsistent_error(c);
+               return -EIO;
+       }
 
-bool bch2_invalidate_bucket(struct bch_fs *c, struct bch_dev *ca,
-                           size_t b, struct bucket_mark *old)
+       m->block_sectors[p.block] += sectors;
+
+       r = m->r;
+       mutex_unlock(&c->ec_stripes_heap_lock);
+
+       r.e.data_type = data_type;
+       update_replicas(c, k, &r.e, sectors, trans->journal_res.seq, true);
+
+       return 0;
+}
+
+static int __mark_extent(struct btree_trans *trans,
+                        enum btree_id btree_id, unsigned level,
+                        struct bkey_s_c k, unsigned flags)
 {
-       struct bucket *g;
-       struct bucket_mark new;
+       u64 journal_seq = trans->journal_res.seq;
+       struct bch_fs *c = trans->c;
+       struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
+       const union bch_extent_entry *entry;
+       struct extent_ptr_decoded p;
+       struct bch_replicas_padded r;
+       enum bch_data_type data_type = bkey_is_btree_ptr(k.k)
+               ? BCH_DATA_btree
+               : BCH_DATA_user;
+       s64 sectors = bkey_is_btree_ptr(k.k)
+               ? btree_sectors(c)
+               : k.k->size;
+       s64 dirty_sectors = 0;
+       bool stale;
+       int ret;
+
+       BUG_ON(!(flags & BTREE_TRIGGER_GC));
+
+       r.e.data_type   = data_type;
+       r.e.nr_devs     = 0;
+       r.e.nr_required = 1;
+
+       bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
+               s64 disk_sectors = ptr_disk_sectors(sectors, p);
+
+               if (flags & BTREE_TRIGGER_OVERWRITE)
+                       disk_sectors = -disk_sectors;
+
+               ret = bch2_mark_pointer(trans, btree_id, level, k, p, disk_sectors, flags);
+               if (ret < 0)
+                       return ret;
+
+               stale = ret > 0;
+
+               if (p.ptr.cached) {
+                       if (!stale) {
+                               ret = update_cached_sectors(c, k, p.ptr.dev,
+                                               disk_sectors, journal_seq, true);
+                               if (ret) {
+                                       bch2_fs_fatal_error(c, "%s(): no replicas entry while updating cached sectors",
+                                                           __func__);
+                                       return ret;
+                               }
+                       }
+               } else if (!p.has_ec) {
+                       dirty_sectors          += disk_sectors;
+                       r.e.devs[r.e.nr_devs++] = p.ptr.dev;
+               } else {
+                       ret = bch2_mark_stripe_ptr(trans, k, p.ec, data_type,
+                                       disk_sectors, flags);
+                       if (ret)
+                               return ret;
+
+                       /*
+                        * There may be other dirty pointers in this extent, but
+                        * if so they're not required for mounting if we have an
+                        * erasure coded pointer in this extent:
+                        */
+                       r.e.nr_required = 0;
+               }
+       }
+
+       if (r.e.nr_devs) {
+               ret = update_replicas(c, k, &r.e, dirty_sectors, journal_seq, true);
+               if (ret) {
+                       struct printbuf buf = PRINTBUF;
+
+                       bch2_bkey_val_to_text(&buf, c, k);
+                       bch2_fs_fatal_error(c, "%s(): no replicas entry for %s", __func__, buf.buf);
+                       printbuf_exit(&buf);
+                       return ret;
+               }
+       }
+
+       return 0;
+}
+
+int bch2_mark_extent(struct btree_trans *trans,
+                    enum btree_id btree_id, unsigned level,
+                    struct bkey_s_c old, struct bkey_s_c new,
+                    unsigned flags)
+{
+       return mem_trigger_run_overwrite_then_insert(__mark_extent, trans, btree_id, level, old, new, flags);
+}
+
+int bch2_mark_stripe(struct btree_trans *trans,
+                    enum btree_id btree_id, unsigned level,
+                    struct bkey_s_c old, struct bkey_s_c new,
+                    unsigned flags)
+{
+       bool gc = flags & BTREE_TRIGGER_GC;
+       u64 journal_seq = trans->journal_res.seq;
+       struct bch_fs *c = trans->c;
+       u64 idx = new.k->p.offset;
+       const struct bch_stripe *old_s = old.k->type == KEY_TYPE_stripe
+               ? bkey_s_c_to_stripe(old).v : NULL;
+       const struct bch_stripe *new_s = new.k->type == KEY_TYPE_stripe
+               ? bkey_s_c_to_stripe(new).v : NULL;
+       unsigned i;
+       int ret;
+
+       BUG_ON(gc && old_s);
+
+       if (!gc) {
+               struct stripe *m = genradix_ptr(&c->stripes, idx);
+
+               if (!m) {
+                       struct printbuf buf1 = PRINTBUF;
+                       struct printbuf buf2 = PRINTBUF;
 
-       percpu_rwsem_assert_held(&c->usage_lock);
+                       bch2_bkey_val_to_text(&buf1, c, old);
+                       bch2_bkey_val_to_text(&buf2, c, new);
+                       bch_err_ratelimited(c, "error marking nonexistent stripe %llu while marking\n"
+                                           "old %s\n"
+                                           "new %s", idx, buf1.buf, buf2.buf);
+                       printbuf_exit(&buf2);
+                       printbuf_exit(&buf1);
+                       bch2_inconsistent_error(c);
+                       return -1;
+               }
+
+               if (!new_s) {
+                       bch2_stripes_heap_del(c, m, idx);
+
+                       memset(m, 0, sizeof(*m));
+               } else {
+                       m->sectors      = le16_to_cpu(new_s->sectors);
+                       m->algorithm    = new_s->algorithm;
+                       m->nr_blocks    = new_s->nr_blocks;
+                       m->nr_redundant = new_s->nr_redundant;
+                       m->blocks_nonempty = 0;
+
+                       for (i = 0; i < new_s->nr_blocks; i++)
+                               m->blocks_nonempty += !!stripe_blockcount_get(new_s, i);
+
+                       if (!old_s)
+                               bch2_stripes_heap_insert(c, m, idx);
+                       else
+                               bch2_stripes_heap_update(c, m, idx);
+               }
+       } else {
+               struct gc_stripe *m =
+                       genradix_ptr_alloc(&c->gc_stripes, idx, GFP_KERNEL);
+
+               if (!m) {
+                       bch_err(c, "error allocating memory for gc_stripes, idx %llu",
+                               idx);
+                       return -BCH_ERR_ENOMEM_mark_stripe;
+               }
+               /*
+                * This will be wrong when we bring back runtime gc: we should
+                * be unmarking the old key and then marking the new key
+                */
+               m->alive        = true;
+               m->sectors      = le16_to_cpu(new_s->sectors);
+               m->nr_blocks    = new_s->nr_blocks;
+               m->nr_redundant = new_s->nr_redundant;
+
+               for (i = 0; i < new_s->nr_blocks; i++)
+                       m->ptrs[i] = new_s->ptrs[i];
+
+               bch2_bkey_to_replicas(&m->r.e, new);
 
-       g = bucket(ca, b);
+               /*
+                * gc recalculates this field from stripe ptr
+                * references:
+                */
+               memset(m->block_sectors, 0, sizeof(m->block_sectors));
 
-       *old = bucket_data_cmpxchg(c, ca, g, new, ({
-               if (!is_available_bucket(new)) {
-                       percpu_up_read_preempt_enable(&c->usage_lock);
-                       return false;
+               for (i = 0; i < new_s->nr_blocks; i++) {
+                       ret = mark_stripe_bucket(trans, new, i, flags);
+                       if (ret)
+                               return ret;
                }
 
-               new.owned_by_allocator  = 1;
-               new.data_type           = 0;
-               new.cached_sectors      = 0;
-               new.dirty_sectors       = 0;
-               new.gen++;
-       }));
+               ret = update_replicas(c, new, &m->r.e,
+                                     ((s64) m->sectors * m->nr_redundant),
+                                     journal_seq, gc);
+               if (ret) {
+                       struct printbuf buf = PRINTBUF;
+
+                       bch2_bkey_val_to_text(&buf, c, new);
+                       bch2_fs_fatal_error(c, "no replicas entry for %s", buf.buf);
+                       printbuf_exit(&buf);
+                       return ret;
+               }
+       }
 
-       if (!old->owned_by_allocator && old->cached_sectors)
-               trace_invalidate(ca, bucket_to_sector(ca, b),
-                                old->cached_sectors);
-       return true;
+       return 0;
 }
 
-void bch2_mark_alloc_bucket(struct bch_fs *c, struct bch_dev *ca,
-                           size_t b, bool owned_by_allocator,
-                           struct gc_pos pos, unsigned flags)
+static int __mark_reservation(struct btree_trans *trans,
+                             enum btree_id btree_id, unsigned level,
+                             struct bkey_s_c k, unsigned flags)
 {
-       struct bucket *g;
-       struct bucket_mark old, new;
+       struct bch_fs *c = trans->c;
+       struct bch_fs_usage *fs_usage;
+       unsigned replicas = bkey_s_c_to_reservation(k).v->nr_replicas;
+       s64 sectors = (s64) k.k->size;
+
+       BUG_ON(!(flags & BTREE_TRIGGER_GC));
+
+       if (flags & BTREE_TRIGGER_OVERWRITE)
+               sectors = -sectors;
+       sectors *= replicas;
 
-       percpu_rwsem_assert_held(&c->usage_lock);
-       g = bucket(ca, b);
+       percpu_down_read(&c->mark_lock);
+       preempt_disable();
 
-       if (!(flags & BCH_BUCKET_MARK_GC_LOCK_HELD) &&
-           gc_will_visit(c, pos))
-               return;
+       fs_usage = fs_usage_ptr(c, trans->journal_res.seq, flags & BTREE_TRIGGER_GC);
+       replicas = clamp_t(unsigned, replicas, 1,
+                          ARRAY_SIZE(fs_usage->persistent_reserved));
 
-       old = bucket_data_cmpxchg(c, ca, g, new, ({
-               new.owned_by_allocator  = owned_by_allocator;
-       }));
+       fs_usage->reserved                              += sectors;
+       fs_usage->persistent_reserved[replicas - 1]     += sectors;
 
-       BUG_ON(!owned_by_allocator && !old.owned_by_allocator &&
-              c->gc_pos.phase == GC_PHASE_DONE);
+       preempt_enable();
+       percpu_up_read(&c->mark_lock);
+
+       return 0;
 }
 
-#define saturated_add(ca, dst, src, max)                       \
-do {                                                           \
-       BUG_ON((int) (dst) + (src) < 0);                        \
-       if ((dst) == (max))                                     \
-               ;                                               \
-       else if ((dst) + (src) <= (max))                        \
-               dst += (src);                                   \
-       else {                                                  \
-               dst = (max);                                    \
-               trace_sectors_saturated(ca);            \
-       }                                                       \
-} while (0)
+int bch2_mark_reservation(struct btree_trans *trans,
+                         enum btree_id btree_id, unsigned level,
+                         struct bkey_s_c old, struct bkey_s_c new,
+                         unsigned flags)
+{
+       return mem_trigger_run_overwrite_then_insert(__mark_reservation, trans, btree_id, level, old, new, flags);
+}
 
-void bch2_mark_metadata_bucket(struct bch_fs *c, struct bch_dev *ca,
-                              size_t b, enum bch_data_type type,
-                              unsigned sectors, struct gc_pos pos,
-                              unsigned flags)
+static s64 __bch2_mark_reflink_p(struct btree_trans *trans,
+                                struct bkey_s_c_reflink_p p,
+                                u64 start, u64 end,
+                                u64 *idx, unsigned flags, size_t r_idx)
 {
-       struct bucket *g;
-       struct bucket_mark old, new;
+       struct bch_fs *c = trans->c;
+       struct reflink_gc *r;
+       int add = !(flags & BTREE_TRIGGER_OVERWRITE) ? 1 : -1;
+       u64 next_idx = end;
+       s64 ret = 0;
+       struct printbuf buf = PRINTBUF;
 
-       BUG_ON(!type);
+       if (r_idx >= c->reflink_gc_nr)
+               goto not_found;
 
-       if (likely(c)) {
-               percpu_rwsem_assert_held(&c->usage_lock);
+       r = genradix_ptr(&c->reflink_gc_table, r_idx);
+       next_idx = min(next_idx, r->offset - r->size);
+       if (*idx < next_idx)
+               goto not_found;
 
-               if (!(flags & BCH_BUCKET_MARK_GC_LOCK_HELD) &&
-                   gc_will_visit(c, pos))
-                       return;
+       BUG_ON((s64) r->refcount + add < 0);
+
+       r->refcount += add;
+       *idx = r->offset;
+       return 0;
+not_found:
+       if (fsck_err(c, reflink_p_to_missing_reflink_v,
+                    "pointer to missing indirect extent\n"
+                    "  %s\n"
+                    "  missing range %llu-%llu",
+                    (bch2_bkey_val_to_text(&buf, c, p.s_c), buf.buf),
+                    *idx, next_idx)) {
+               struct bkey_i_error *new;
+
+               new = bch2_trans_kmalloc(trans, sizeof(*new));
+               ret = PTR_ERR_OR_ZERO(new);
+               if (ret)
+                       goto err;
+
+               bkey_init(&new->k);
+               new->k.type     = KEY_TYPE_error;
+               new->k.p                = bkey_start_pos(p.k);
+               new->k.p.offset += *idx - start;
+               bch2_key_resize(&new->k, next_idx - *idx);
+               ret = bch2_btree_insert_trans(trans, BTREE_ID_extents, &new->k_i,
+                                         BTREE_TRIGGER_NORUN);
        }
 
-       rcu_read_lock();
+       *idx = next_idx;
+err:
+fsck_err:
+       printbuf_exit(&buf);
+       return ret;
+}
 
-       g = bucket(ca, b);
-       old = bucket_data_cmpxchg(c, ca, g, new, ({
-               saturated_add(ca, new.dirty_sectors, sectors,
-                             GC_MAX_SECTORS_USED);
-               new.data_type           = type;
-       }));
+static int __mark_reflink_p(struct btree_trans *trans,
+                           enum btree_id btree_id, unsigned level,
+                           struct bkey_s_c k, unsigned flags)
+{
+       struct bch_fs *c = trans->c;
+       struct bkey_s_c_reflink_p p = bkey_s_c_to_reflink_p(k);
+       struct reflink_gc *ref;
+       size_t l, r, m;
+       u64 idx = le64_to_cpu(p.v->idx), start = idx;
+       u64 end = le64_to_cpu(p.v->idx) + p.k->size;
+       int ret = 0;
+
+       BUG_ON(!(flags & BTREE_TRIGGER_GC));
+
+       if (c->sb.version_upgrade_complete >= bcachefs_metadata_version_reflink_p_fix) {
+               idx -= le32_to_cpu(p.v->front_pad);
+               end += le32_to_cpu(p.v->back_pad);
+       }
 
-       rcu_read_unlock();
+       l = 0;
+       r = c->reflink_gc_nr;
+       while (l < r) {
+               m = l + (r - l) / 2;
+
+               ref = genradix_ptr(&c->reflink_gc_table, m);
+               if (ref->offset <= idx)
+                       l = m + 1;
+               else
+                       r = m;
+       }
 
-       BUG_ON(!(flags & BCH_BUCKET_MARK_MAY_MAKE_UNAVAILABLE) &&
-              bucket_became_unavailable(c, old, new));
+       while (idx < end && !ret)
+               ret = __bch2_mark_reflink_p(trans, p, start, end,
+                                           &idx, flags, l++);
+
+       return ret;
 }
 
-/* Reverting this until the copygc + compression issue is fixed: */
+int bch2_mark_reflink_p(struct btree_trans *trans,
+                       enum btree_id btree_id, unsigned level,
+                       struct bkey_s_c old, struct bkey_s_c new,
+                       unsigned flags)
+{
+       return mem_trigger_run_overwrite_then_insert(__mark_reflink_p, trans, btree_id, level, old, new, flags);
+}
 
-static int __disk_sectors(struct bch_extent_crc_unpacked crc, unsigned sectors)
+void bch2_trans_fs_usage_revert(struct btree_trans *trans,
+                               struct replicas_delta_list *deltas)
 {
-       if (!sectors)
-               return 0;
+       struct bch_fs *c = trans->c;
+       struct bch_fs_usage *dst;
+       struct replicas_delta *d, *top = (void *) deltas->d + deltas->used;
+       s64 added = 0;
+       unsigned i;
+
+       percpu_down_read(&c->mark_lock);
+       preempt_disable();
+       dst = fs_usage_ptr(c, trans->journal_res.seq, false);
+
+       /* revert changes: */
+       for (d = deltas->d; d != top; d = replicas_delta_next(d)) {
+               switch (d->r.data_type) {
+               case BCH_DATA_btree:
+               case BCH_DATA_user:
+               case BCH_DATA_parity:
+                       added += d->delta;
+               }
+               BUG_ON(__update_replicas(c, dst, &d->r, -d->delta));
+       }
 
-       return max(1U, DIV_ROUND_UP(sectors * crc.compressed_size,
-                                   crc.uncompressed_size));
+       dst->nr_inodes -= deltas->nr_inodes;
+
+       for (i = 0; i < BCH_REPLICAS_MAX; i++) {
+               added                           -= deltas->persistent_reserved[i];
+               dst->reserved                   -= deltas->persistent_reserved[i];
+               dst->persistent_reserved[i]     -= deltas->persistent_reserved[i];
+       }
+
+       if (added > 0) {
+               trans->disk_res->sectors += added;
+               this_cpu_add(*c->online_reserved, added);
+       }
+
+       preempt_enable();
+       percpu_up_read(&c->mark_lock);
 }
 
-/*
- * Checking against gc's position has to be done here, inside the cmpxchg()
- * loop, to avoid racing with the start of gc clearing all the marks - GC does
- * that with the gc pos seqlock held.
- */
-static void bch2_mark_pointer(struct bch_fs *c,
-                             struct bkey_s_c_extent e,
-                             const struct bch_extent_ptr *ptr,
-                             struct bch_extent_crc_unpacked crc,
-                             s64 sectors, enum s_alloc type,
-                             struct bch_fs_usage *stats,
-                             u64 journal_seq, unsigned flags)
-{
-       struct bucket_mark old, new;
-       unsigned saturated;
-       struct bch_dev *ca = bch_dev_bkey_exists(c, ptr->dev);
-       struct bucket *g = PTR_BUCKET(ca, ptr);
-       enum bch_data_type data_type = type == S_META
-               ? BCH_DATA_BTREE : BCH_DATA_USER;
-       u64 v;
+int bch2_trans_fs_usage_apply(struct btree_trans *trans,
+                             struct replicas_delta_list *deltas)
+{
+       struct bch_fs *c = trans->c;
+       static int warned_disk_usage = 0;
+       bool warn = false;
+       u64 disk_res_sectors = trans->disk_res ? trans->disk_res->sectors : 0;
+       struct replicas_delta *d, *d2;
+       struct replicas_delta *top = (void *) deltas->d + deltas->used;
+       struct bch_fs_usage *dst;
+       s64 added = 0, should_not_have_added;
+       unsigned i;
 
-       if (crc.compression_type) {
-               unsigned old_sectors, new_sectors;
+       percpu_down_read(&c->mark_lock);
+       preempt_disable();
+       dst = fs_usage_ptr(c, trans->journal_res.seq, false);
 
-               if (sectors > 0) {
-                       old_sectors = 0;
-                       new_sectors = sectors;
-               } else {
-                       old_sectors = e.k->size;
-                       new_sectors = e.k->size + sectors;
+       for (d = deltas->d; d != top; d = replicas_delta_next(d)) {
+               switch (d->r.data_type) {
+               case BCH_DATA_btree:
+               case BCH_DATA_user:
+               case BCH_DATA_parity:
+                       added += d->delta;
                }
 
-               sectors = -__disk_sectors(crc, old_sectors)
-                         +__disk_sectors(crc, new_sectors);
+               if (__update_replicas(c, dst, &d->r, d->delta))
+                       goto need_mark;
        }
 
-       if (flags & BCH_BUCKET_MARK_GC_WILL_VISIT) {
-               if (journal_seq)
-                       bucket_cmpxchg(g, new, ({
-                               new.journal_seq_valid   = 1;
-                               new.journal_seq         = journal_seq;
-                       }));
+       dst->nr_inodes += deltas->nr_inodes;
 
-               return;
+       for (i = 0; i < BCH_REPLICAS_MAX; i++) {
+               added                           += deltas->persistent_reserved[i];
+               dst->reserved                   += deltas->persistent_reserved[i];
+               dst->persistent_reserved[i]     += deltas->persistent_reserved[i];
        }
 
-       v = atomic64_read(&g->_mark.v);
-       do {
-               new.v.counter = old.v.counter = v;
-               saturated = 0;
+       /*
+        * Not allowed to reduce sectors_available except by getting a
+        * reservation:
+        */
+       should_not_have_added = added - (s64) disk_res_sectors;
+       if (unlikely(should_not_have_added > 0)) {
+               u64 old, new, v = atomic64_read(&c->sectors_available);
+
+               do {
+                       old = v;
+                       new = max_t(s64, 0, old - should_not_have_added);
+               } while ((v = atomic64_cmpxchg(&c->sectors_available,
+                                              old, new)) != old);
+
+               added -= should_not_have_added;
+               warn = true;
+       }
 
-               /*
-                * Check this after reading bucket mark to guard against
-                * the allocator invalidating a bucket after we've already
-                * checked the gen
-                */
-               if (gen_after(new.gen, ptr->gen)) {
-                       BUG_ON(!test_bit(BCH_FS_ALLOC_READ_DONE, &c->flags));
-                       EBUG_ON(!ptr->cached &&
-                               test_bit(JOURNAL_REPLAY_DONE, &c->journal.flags));
-                       return;
-               }
+       if (added > 0) {
+               trans->disk_res->sectors -= added;
+               this_cpu_sub(*c->online_reserved, added);
+       }
 
-               if (!ptr->cached &&
-                   new.dirty_sectors == GC_MAX_SECTORS_USED &&
-                   sectors < 0)
-                       saturated = -sectors;
+       preempt_enable();
+       percpu_up_read(&c->mark_lock);
 
-               if (ptr->cached)
-                       saturated_add(ca, new.cached_sectors, sectors,
-                                     GC_MAX_SECTORS_USED);
-               else
-                       saturated_add(ca, new.dirty_sectors, sectors,
-                                     GC_MAX_SECTORS_USED);
+       if (unlikely(warn) && !xchg(&warned_disk_usage, 1))
+               bch2_trans_inconsistent(trans,
+                                       "disk usage increased %lli more than %llu sectors reserved)",
+                                       should_not_have_added, disk_res_sectors);
+       return 0;
+need_mark:
+       /* revert changes: */
+       for (d2 = deltas->d; d2 != d; d2 = replicas_delta_next(d2))
+               BUG_ON(__update_replicas(c, dst, &d2->r, -d2->delta));
+
+       preempt_enable();
+       percpu_up_read(&c->mark_lock);
+       return -1;
+}
+
+/* trans_mark: */
+
+static inline int bch2_trans_mark_pointer(struct btree_trans *trans,
+                                  enum btree_id btree_id, unsigned level,
+                                  struct bkey_s_c k, struct extent_ptr_decoded p,
+                                  unsigned flags)
+{
+       bool insert = !(flags & BTREE_TRIGGER_OVERWRITE);
+       struct btree_iter iter;
+       struct bkey_i_alloc_v4 *a;
+       struct bpos bucket;
+       struct bch_backpointer bp;
+       s64 sectors;
+       int ret;
+
+       bch2_extent_ptr_to_bp(trans->c, btree_id, level, k, p, &bucket, &bp);
+       sectors = bp.bucket_len;
+       if (!insert)
+               sectors = -sectors;
+
+       a = bch2_trans_start_alloc_update(trans, &iter, bucket);
+       if (IS_ERR(a))
+               return PTR_ERR(a);
+
+       ret = __mark_pointer(trans, k, &p.ptr, sectors, bp.data_type,
+                            a->v.gen, &a->v.data_type,
+                            &a->v.dirty_sectors, &a->v.cached_sectors) ?:
+               bch2_trans_update(trans, &iter, &a->k_i, 0);
+       bch2_trans_iter_exit(trans, &iter);
 
-               if (!new.dirty_sectors &&
-                   !new.cached_sectors) {
-                       new.data_type   = 0;
+       if (ret)
+               return ret;
 
-                       if (journal_seq) {
-                               new.journal_seq_valid = 1;
-                               new.journal_seq = journal_seq;
+       if (!p.ptr.cached) {
+               ret = bch2_bucket_backpointer_mod(trans, bucket, bp, k, insert);
+               if (ret)
+                       return ret;
+       }
+
+       return 0;
+}
+
+static int bch2_trans_mark_stripe_ptr(struct btree_trans *trans,
+                       struct extent_ptr_decoded p,
+                       s64 sectors, enum bch_data_type data_type)
+{
+       struct btree_iter iter;
+       struct bkey_i_stripe *s;
+       struct bch_replicas_padded r;
+       int ret = 0;
+
+       s = bch2_bkey_get_mut_typed(trans, &iter,
+                       BTREE_ID_stripes, POS(0, p.ec.idx),
+                       BTREE_ITER_WITH_UPDATES, stripe);
+       ret = PTR_ERR_OR_ZERO(s);
+       if (unlikely(ret)) {
+               bch2_trans_inconsistent_on(bch2_err_matches(ret, ENOENT), trans,
+                       "pointer to nonexistent stripe %llu",
+                       (u64) p.ec.idx);
+               goto err;
+       }
+
+       if (!bch2_ptr_matches_stripe(&s->v, p)) {
+               bch2_trans_inconsistent(trans,
+                       "stripe pointer doesn't match stripe %llu",
+                       (u64) p.ec.idx);
+               ret = -EIO;
+               goto err;
+       }
+
+       stripe_blockcount_set(&s->v, p.ec.block,
+               stripe_blockcount_get(&s->v, p.ec.block) +
+               sectors);
+
+       bch2_bkey_to_replicas(&r.e, bkey_i_to_s_c(&s->k_i));
+       r.e.data_type = data_type;
+       ret = update_replicas_list(trans, &r.e, sectors);
+err:
+       bch2_trans_iter_exit(trans, &iter);
+       return ret;
+}
+
+static int __trans_mark_extent(struct btree_trans *trans,
+                              enum btree_id btree_id, unsigned level,
+                              struct bkey_s_c k, unsigned flags)
+{
+       struct bch_fs *c = trans->c;
+       struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
+       const union bch_extent_entry *entry;
+       struct extent_ptr_decoded p;
+       struct bch_replicas_padded r;
+       enum bch_data_type data_type = bkey_is_btree_ptr(k.k)
+               ? BCH_DATA_btree
+               : BCH_DATA_user;
+       s64 sectors = bkey_is_btree_ptr(k.k)
+               ? btree_sectors(c)
+               : k.k->size;
+       s64 dirty_sectors = 0;
+       bool stale;
+       int ret = 0;
+
+       r.e.data_type   = data_type;
+       r.e.nr_devs     = 0;
+       r.e.nr_required = 1;
+
+       bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
+               s64 disk_sectors = ptr_disk_sectors(sectors, p);
+
+               if (flags & BTREE_TRIGGER_OVERWRITE)
+                       disk_sectors = -disk_sectors;
+
+               ret = bch2_trans_mark_pointer(trans, btree_id, level, k, p, flags);
+               if (ret < 0)
+                       return ret;
+
+               stale = ret > 0;
+
+               if (p.ptr.cached) {
+                       if (!stale) {
+                               ret = update_cached_sectors_list(trans, p.ptr.dev,
+                                                                disk_sectors);
+                               if (ret)
+                                       return ret;
                        }
+               } else if (!p.has_ec) {
+                       dirty_sectors          += disk_sectors;
+                       r.e.devs[r.e.nr_devs++] = p.ptr.dev;
                } else {
-                       new.data_type = data_type;
+                       ret = bch2_trans_mark_stripe_ptr(trans, p,
+                                       disk_sectors, data_type);
+                       if (ret)
+                               return ret;
+
+                       r.e.nr_required = 0;
                }
+       }
+
+       if (r.e.nr_devs)
+               ret = update_replicas_list(trans, &r.e, dirty_sectors);
+
+       return ret;
+}
+
+int bch2_trans_mark_extent(struct btree_trans *trans,
+                          enum btree_id btree_id, unsigned level,
+                          struct bkey_s_c old, struct bkey_i *new,
+                          unsigned flags)
+{
+       struct bch_fs *c = trans->c;
+       int mod = (int) bch2_bkey_needs_rebalance(c, bkey_i_to_s_c(new)) -
+                 (int) bch2_bkey_needs_rebalance(c, old);
+
+       if (mod) {
+               int ret = bch2_btree_bit_mod(trans, BTREE_ID_rebalance_work, new->k.p, mod > 0);
+               if (ret)
+                       return ret;
+       }
+
+       return trigger_run_overwrite_then_insert(__trans_mark_extent, trans, btree_id, level, old, new, flags);
+}
+
+static int bch2_trans_mark_stripe_bucket(struct btree_trans *trans,
+                                        struct bkey_s_c_stripe s,
+                                        unsigned idx, bool deleting)
+{
+       struct bch_fs *c = trans->c;
+       const struct bch_extent_ptr *ptr = &s.v->ptrs[idx];
+       struct btree_iter iter;
+       struct bkey_i_alloc_v4 *a;
+       enum bch_data_type data_type = idx >= s.v->nr_blocks - s.v->nr_redundant
+               ? BCH_DATA_parity : 0;
+       s64 sectors = data_type ? le16_to_cpu(s.v->sectors) : 0;
+       int ret = 0;
+
+       if (deleting)
+               sectors = -sectors;
+
+       a = bch2_trans_start_alloc_update(trans, &iter, PTR_BUCKET_POS(c, ptr));
+       if (IS_ERR(a))
+               return PTR_ERR(a);
+
+       ret = check_bucket_ref(trans, s.s_c, ptr, sectors, data_type,
+                              a->v.gen, a->v.data_type,
+                              a->v.dirty_sectors, a->v.cached_sectors);
+       if (ret)
+               goto err;
 
-               if (flags & BCH_BUCKET_MARK_NOATOMIC) {
-                       g->_mark = new;
-                       break;
+       if (!deleting) {
+               if (bch2_trans_inconsistent_on(a->v.stripe ||
+                                              a->v.stripe_redundancy, trans,
+                               "bucket %llu:%llu gen %u data type %s dirty_sectors %u: multiple stripes using same bucket (%u, %llu)",
+                               iter.pos.inode, iter.pos.offset, a->v.gen,
+                               bch2_data_types[a->v.data_type],
+                               a->v.dirty_sectors,
+                               a->v.stripe, s.k->p.offset)) {
+                       ret = -EIO;
+                       goto err;
                }
-       } while ((v = atomic64_cmpxchg(&g->_mark.v,
-                             old.v.counter,
-                             new.v.counter)) != old.v.counter);
-
-       bch2_dev_usage_update(c, ca, old, new);
-
-       BUG_ON(!(flags & BCH_BUCKET_MARK_MAY_MAKE_UNAVAILABLE) &&
-              bucket_became_unavailable(c, old, new));
-
-       if (saturated &&
-           atomic_long_add_return(saturated,
-                                  &ca->saturated_count) >=
-           bucket_to_sector(ca, ca->free_inc.size)) {
-               if (c->gc_thread) {
-                       trace_gc_sectors_saturated(c);
-                       wake_up_process(c->gc_thread);
+
+               if (bch2_trans_inconsistent_on(data_type && a->v.dirty_sectors, trans,
+                               "bucket %llu:%llu gen %u data type %s dirty_sectors %u: data already in stripe bucket %llu",
+                               iter.pos.inode, iter.pos.offset, a->v.gen,
+                               bch2_data_types[a->v.data_type],
+                               a->v.dirty_sectors,
+                               s.k->p.offset)) {
+                       ret = -EIO;
+                       goto err;
+               }
+
+               a->v.stripe             = s.k->p.offset;
+               a->v.stripe_redundancy  = s.v->nr_redundant;
+               a->v.data_type          = BCH_DATA_stripe;
+       } else {
+               if (bch2_trans_inconsistent_on(a->v.stripe != s.k->p.offset ||
+                                              a->v.stripe_redundancy != s.v->nr_redundant, trans,
+                               "bucket %llu:%llu gen %u: not marked as stripe when deleting stripe %llu (got %u)",
+                               iter.pos.inode, iter.pos.offset, a->v.gen,
+                               s.k->p.offset, a->v.stripe)) {
+                       ret = -EIO;
+                       goto err;
                }
+
+               a->v.stripe             = 0;
+               a->v.stripe_redundancy  = 0;
+               a->v.data_type          = alloc_data_type(a->v, BCH_DATA_user);
        }
+
+       a->v.dirty_sectors += sectors;
+       if (data_type)
+               a->v.data_type = !deleting ? data_type : 0;
+
+       ret = bch2_trans_update(trans, &iter, &a->k_i, 0);
+       if (ret)
+               goto err;
+err:
+       bch2_trans_iter_exit(trans, &iter);
+       return ret;
 }
 
-void bch2_mark_key(struct bch_fs *c, struct bkey_s_c k,
-                  s64 sectors, bool metadata,
-                  struct gc_pos pos,
-                  struct bch_fs_usage *stats,
-                  u64 journal_seq, unsigned flags)
+int bch2_trans_mark_stripe(struct btree_trans *trans,
+                          enum btree_id btree_id, unsigned level,
+                          struct bkey_s_c old, struct bkey_i *new,
+                          unsigned flags)
 {
+       const struct bch_stripe *old_s = NULL;
+       struct bch_stripe *new_s = NULL;
+       struct bch_replicas_padded r;
+       unsigned i, nr_blocks;
+       int ret = 0;
+
+       if (old.k->type == KEY_TYPE_stripe)
+               old_s = bkey_s_c_to_stripe(old).v;
+       if (new->k.type == KEY_TYPE_stripe)
+               new_s = &bkey_i_to_stripe(new)->v;
+
        /*
-        * synchronization w.r.t. GC:
-        *
-        * Normally, bucket sector counts/marks are updated on the fly, as
-        * references are added/removed from the btree, the lists of buckets the
-        * allocator owns, other metadata buckets, etc.
-        *
-        * When GC is in progress and going to mark this reference, we do _not_
-        * mark this reference here, to avoid double counting - GC will count it
-        * when it gets to it.
-        *
-        * To know whether we should mark a given reference (GC either isn't
-        * running, or has already marked references at this position) we
-        * construct a total order for everything GC walks. Then, we can simply
-        * compare the position of the reference we're marking - @pos - with
-        * GC's current position. If GC is going to mark this reference, GC's
-        * current position will be less than @pos; if GC's current position is
-        * greater than @pos GC has either already walked this position, or
-        * isn't running.
-        *
-        * To avoid racing with GC's position changing, we have to deal with
-        *  - GC's position being set to GC_POS_MIN when GC starts:
-        *    usage_lock guards against this
-        *  - GC's position overtaking @pos: we guard against this with
-        *    whatever lock protects the data structure the reference lives in
-        *    (e.g. the btree node lock, or the relevant allocator lock).
+        * If the pointers aren't changing, we don't need to do anything:
         */
+       if (new_s && old_s &&
+           new_s->nr_blocks    == old_s->nr_blocks &&
+           new_s->nr_redundant == old_s->nr_redundant &&
+           !memcmp(old_s->ptrs, new_s->ptrs,
+                   new_s->nr_blocks * sizeof(struct bch_extent_ptr)))
+               return 0;
+
+       BUG_ON(new_s && old_s &&
+              (new_s->nr_blocks        != old_s->nr_blocks ||
+               new_s->nr_redundant     != old_s->nr_redundant));
+
+       nr_blocks = new_s ? new_s->nr_blocks : old_s->nr_blocks;
 
-       percpu_down_read_preempt_disable(&c->usage_lock);
-       if (!(flags & BCH_BUCKET_MARK_GC_LOCK_HELD) &&
-           gc_will_visit(c, pos))
-               flags |= BCH_BUCKET_MARK_GC_WILL_VISIT;
-
-       if (!stats)
-               stats = this_cpu_ptr(c->usage_percpu);
-
-       switch (k.k->type) {
-       case BCH_EXTENT:
-       case BCH_EXTENT_CACHED: {
-               struct bkey_s_c_extent e = bkey_s_c_to_extent(k);
-               const struct bch_extent_ptr *ptr;
-               struct bch_extent_crc_unpacked crc;
-               enum s_alloc type = metadata ? S_META : S_DIRTY;
-               unsigned replicas = 0;
-
-               BUG_ON(metadata && bkey_extent_is_cached(e.k));
-               BUG_ON(!sectors);
-
-               extent_for_each_ptr_crc(e, ptr, crc) {
-                       bch2_mark_pointer(c, e, ptr, crc, sectors, type,
-                                         stats, journal_seq, flags);
-                       replicas += !ptr->cached;
+       if (new_s) {
+               s64 sectors = le16_to_cpu(new_s->sectors);
+
+               bch2_bkey_to_replicas(&r.e, bkey_i_to_s_c(new));
+               ret = update_replicas_list(trans, &r.e, sectors * new_s->nr_redundant);
+               if (ret)
+                       return ret;
+       }
+
+       if (old_s) {
+               s64 sectors = -((s64) le16_to_cpu(old_s->sectors));
+
+               bch2_bkey_to_replicas(&r.e, old);
+               ret = update_replicas_list(trans, &r.e, sectors * old_s->nr_redundant);
+               if (ret)
+                       return ret;
+       }
+
+       for (i = 0; i < nr_blocks; i++) {
+               if (new_s && old_s &&
+                   !memcmp(&new_s->ptrs[i],
+                           &old_s->ptrs[i],
+                           sizeof(new_s->ptrs[i])))
+                       continue;
+
+               if (new_s) {
+                       ret = bch2_trans_mark_stripe_bucket(trans,
+                                       bkey_i_to_s_c_stripe(new), i, false);
+                       if (ret)
+                               break;
                }
 
-               if (replicas) {
-                       BUG_ON(replicas - 1 > ARRAY_SIZE(stats->s));
-                       stats->s[replicas - 1].data[type] += sectors;
+               if (old_s) {
+                       ret = bch2_trans_mark_stripe_bucket(trans,
+                                       bkey_s_c_to_stripe(old), i, true);
+                       if (ret)
+                               break;
                }
-               break;
        }
-       case BCH_RESERVATION: {
-               struct bkey_s_c_reservation r = bkey_s_c_to_reservation(k);
 
-               if (r.v->nr_replicas) {
-                       BUG_ON(r.v->nr_replicas - 1 > ARRAY_SIZE(stats->s));
-                       stats->s[r.v->nr_replicas - 1].persistent_reserved += sectors;
-               }
-               break;
+       return ret;
+}
+
+static int __trans_mark_reservation(struct btree_trans *trans,
+                                   enum btree_id btree_id, unsigned level,
+                                   struct bkey_s_c k, unsigned flags)
+{
+       unsigned replicas = bkey_s_c_to_reservation(k).v->nr_replicas;
+       s64 sectors = (s64) k.k->size;
+       struct replicas_delta_list *d;
+       int ret;
+
+       if (flags & BTREE_TRIGGER_OVERWRITE)
+               sectors = -sectors;
+       sectors *= replicas;
+
+       ret = bch2_replicas_deltas_realloc(trans, 0);
+       if (ret)
+               return ret;
+
+       d = trans->fs_usage_deltas;
+       replicas = clamp_t(unsigned, replicas, 1,
+                          ARRAY_SIZE(d->persistent_reserved));
+
+       d->persistent_reserved[replicas - 1] += sectors;
+       return 0;
+}
+
+int bch2_trans_mark_reservation(struct btree_trans *trans,
+                               enum btree_id btree_id, unsigned level,
+                               struct bkey_s_c old,
+                               struct bkey_i *new,
+                               unsigned flags)
+{
+       return trigger_run_overwrite_then_insert(__trans_mark_reservation, trans, btree_id, level, old, new, flags);
+}
+
+static int trans_mark_reflink_p_segment(struct btree_trans *trans,
+                       struct bkey_s_c_reflink_p p,
+                       u64 *idx, unsigned flags)
+{
+       struct bch_fs *c = trans->c;
+       struct btree_iter iter;
+       struct bkey_i *k;
+       __le64 *refcount;
+       int add = !(flags & BTREE_TRIGGER_OVERWRITE) ? 1 : -1;
+       struct printbuf buf = PRINTBUF;
+       int ret;
+
+       k = bch2_bkey_get_mut_noupdate(trans, &iter,
+                       BTREE_ID_reflink, POS(0, *idx),
+                       BTREE_ITER_WITH_UPDATES);
+       ret = PTR_ERR_OR_ZERO(k);
+       if (ret)
+               goto err;
+
+       refcount = bkey_refcount(k);
+       if (!refcount) {
+               bch2_bkey_val_to_text(&buf, c, p.s_c);
+               bch2_trans_inconsistent(trans,
+                       "nonexistent indirect extent at %llu while marking\n  %s",
+                       *idx, buf.buf);
+               ret = -EIO;
+               goto err;
        }
+
+       if (!*refcount && (flags & BTREE_TRIGGER_OVERWRITE)) {
+               bch2_bkey_val_to_text(&buf, c, p.s_c);
+               bch2_trans_inconsistent(trans,
+                       "indirect extent refcount underflow at %llu while marking\n  %s",
+                       *idx, buf.buf);
+               ret = -EIO;
+               goto err;
        }
-       percpu_up_read_preempt_enable(&c->usage_lock);
+
+       if (flags & BTREE_TRIGGER_INSERT) {
+               struct bch_reflink_p *v = (struct bch_reflink_p *) p.v;
+               u64 pad;
+
+               pad = max_t(s64, le32_to_cpu(v->front_pad),
+                           le64_to_cpu(v->idx) - bkey_start_offset(&k->k));
+               BUG_ON(pad > U32_MAX);
+               v->front_pad = cpu_to_le32(pad);
+
+               pad = max_t(s64, le32_to_cpu(v->back_pad),
+                           k->k.p.offset - p.k->size - le64_to_cpu(v->idx));
+               BUG_ON(pad > U32_MAX);
+               v->back_pad = cpu_to_le32(pad);
+       }
+
+       le64_add_cpu(refcount, add);
+
+       bch2_btree_iter_set_pos_to_extent_start(&iter);
+       ret = bch2_trans_update(trans, &iter, k, 0);
+       if (ret)
+               goto err;
+
+       *idx = k->k.p.offset;
+err:
+       bch2_trans_iter_exit(trans, &iter);
+       printbuf_exit(&buf);
+       return ret;
 }
 
-/* Disk reservations: */
+static int __trans_mark_reflink_p(struct btree_trans *trans,
+                               enum btree_id btree_id, unsigned level,
+                               struct bkey_s_c k, unsigned flags)
+{
+       struct bkey_s_c_reflink_p p = bkey_s_c_to_reflink_p(k);
+       u64 idx, end_idx;
+       int ret = 0;
+
+       idx     = le64_to_cpu(p.v->idx) - le32_to_cpu(p.v->front_pad);
+       end_idx = le64_to_cpu(p.v->idx) + p.k->size +
+               le32_to_cpu(p.v->back_pad);
+
+       while (idx < end_idx && !ret)
+               ret = trans_mark_reflink_p_segment(trans, p, &idx, flags);
+       return ret;
+}
+
+int bch2_trans_mark_reflink_p(struct btree_trans *trans,
+                             enum btree_id btree_id, unsigned level,
+                             struct bkey_s_c old,
+                             struct bkey_i *new,
+                             unsigned flags)
+{
+       if (flags & BTREE_TRIGGER_INSERT) {
+               struct bch_reflink_p *v = &bkey_i_to_reflink_p(new)->v;
+
+               v->front_pad = v->back_pad = 0;
+       }
+
+       return trigger_run_overwrite_then_insert(__trans_mark_reflink_p, trans, btree_id, level, old, new, flags);
+}
+
+static int __bch2_trans_mark_metadata_bucket(struct btree_trans *trans,
+                                   struct bch_dev *ca, size_t b,
+                                   enum bch_data_type type,
+                                   unsigned sectors)
+{
+       struct bch_fs *c = trans->c;
+       struct btree_iter iter;
+       struct bkey_i_alloc_v4 *a;
+       int ret = 0;
+
+       /*
+        * Backup superblock might be past the end of our normal usable space:
+        */
+       if (b >= ca->mi.nbuckets)
+               return 0;
+
+       a = bch2_trans_start_alloc_update(trans, &iter, POS(ca->dev_idx, b));
+       if (IS_ERR(a))
+               return PTR_ERR(a);
+
+       if (a->v.data_type && type && a->v.data_type != type) {
+               bch2_fsck_err(c, FSCK_CAN_IGNORE|FSCK_NEED_FSCK,
+                             BCH_FSCK_ERR_bucket_metadata_type_mismatch,
+                       "bucket %llu:%llu gen %u different types of data in same bucket: %s, %s\n"
+                       "while marking %s",
+                       iter.pos.inode, iter.pos.offset, a->v.gen,
+                       bch2_data_types[a->v.data_type],
+                       bch2_data_types[type],
+                       bch2_data_types[type]);
+               ret = -EIO;
+               goto err;
+       }
 
-static u64 __recalc_sectors_available(struct bch_fs *c)
+       if (a->v.data_type      != type ||
+           a->v.dirty_sectors  != sectors) {
+               a->v.data_type          = type;
+               a->v.dirty_sectors      = sectors;
+               ret = bch2_trans_update(trans, &iter, &a->k_i, 0);
+       }
+err:
+       bch2_trans_iter_exit(trans, &iter);
+       return ret;
+}
+
+int bch2_trans_mark_metadata_bucket(struct btree_trans *trans,
+                                   struct bch_dev *ca, size_t b,
+                                   enum bch_data_type type,
+                                   unsigned sectors)
+{
+       return commit_do(trans, NULL, NULL, 0,
+                       __bch2_trans_mark_metadata_bucket(trans, ca, b, type, sectors));
+}
+
+static int bch2_trans_mark_metadata_sectors(struct btree_trans *trans,
+                                           struct bch_dev *ca,
+                                           u64 start, u64 end,
+                                           enum bch_data_type type,
+                                           u64 *bucket, unsigned *bucket_sectors)
 {
-       int cpu;
+       do {
+               u64 b = sector_to_bucket(ca, start);
+               unsigned sectors =
+                       min_t(u64, bucket_to_sector(ca, b + 1), end) - start;
+
+               if (b != *bucket && *bucket_sectors) {
+                       int ret = bch2_trans_mark_metadata_bucket(trans, ca, *bucket,
+                                                                 type, *bucket_sectors);
+                       if (ret)
+                               return ret;
+
+                       *bucket_sectors = 0;
+               }
 
-       for_each_possible_cpu(cpu)
-               per_cpu_ptr(c->usage_percpu, cpu)->available_cache = 0;
+               *bucket         = b;
+               *bucket_sectors += sectors;
+               start += sectors;
+       } while (start < end);
 
-       return bch2_fs_sectors_free(c, bch2_fs_usage_read(c));
+       return 0;
 }
 
-/* Used by gc when it's starting: */
-void bch2_recalc_sectors_available(struct bch_fs *c)
+static int __bch2_trans_mark_dev_sb(struct btree_trans *trans,
+                                   struct bch_dev *ca)
 {
-       percpu_down_write(&c->usage_lock);
-       atomic64_set(&c->sectors_available, __recalc_sectors_available(c));
-       percpu_up_write(&c->usage_lock);
+       struct bch_sb_layout *layout = &ca->disk_sb.sb->layout;
+       u64 bucket = 0;
+       unsigned i, bucket_sectors = 0;
+       int ret;
+
+       for (i = 0; i < layout->nr_superblocks; i++) {
+               u64 offset = le64_to_cpu(layout->sb_offset[i]);
+
+               if (offset == BCH_SB_SECTOR) {
+                       ret = bch2_trans_mark_metadata_sectors(trans, ca,
+                                               0, BCH_SB_SECTOR,
+                                               BCH_DATA_sb, &bucket, &bucket_sectors);
+                       if (ret)
+                               return ret;
+               }
+
+               ret = bch2_trans_mark_metadata_sectors(trans, ca, offset,
+                                     offset + (1 << layout->sb_max_size_bits),
+                                     BCH_DATA_sb, &bucket, &bucket_sectors);
+               if (ret)
+                       return ret;
+       }
+
+       if (bucket_sectors) {
+               ret = bch2_trans_mark_metadata_bucket(trans, ca,
+                               bucket, BCH_DATA_sb, bucket_sectors);
+               if (ret)
+                       return ret;
+       }
+
+       for (i = 0; i < ca->journal.nr; i++) {
+               ret = bch2_trans_mark_metadata_bucket(trans, ca,
+                               ca->journal.buckets[i],
+                               BCH_DATA_journal, ca->mi.bucket_size);
+               if (ret)
+                       return ret;
+       }
+
+       return 0;
 }
 
-void __bch2_disk_reservation_put(struct bch_fs *c, struct disk_reservation *res)
+int bch2_trans_mark_dev_sb(struct bch_fs *c, struct bch_dev *ca)
 {
-       percpu_down_read_preempt_disable(&c->usage_lock);
-       this_cpu_sub(c->usage_percpu->online_reserved,
-                    res->sectors);
+       int ret = bch2_trans_run(c, __bch2_trans_mark_dev_sb(trans, ca));
+
+       if (ret)
+               bch_err_fn(c, ret);
+       return ret;
+}
 
-       bch2_fs_stats_verify(c);
-       percpu_up_read_preempt_enable(&c->usage_lock);
+int bch2_trans_mark_dev_sbs(struct bch_fs *c)
+{
+       struct bch_dev *ca;
+       unsigned i;
 
-       res->sectors = 0;
+       for_each_online_member(ca, c, i) {
+               int ret = bch2_trans_mark_dev_sb(c, ca);
+               if (ret) {
+                       percpu_ref_put(&ca->ref);
+                       return ret;
+               }
+       }
+
+       return 0;
 }
 
+/* Disk reservations: */
+
 #define SECTORS_CACHE  1024
 
-int bch2_disk_reservation_add(struct bch_fs *c, struct disk_reservation *res,
-                             unsigned sectors, int flags)
+int __bch2_disk_reservation_add(struct bch_fs *c, struct disk_reservation *res,
+                             u64 sectors, int flags)
 {
-       struct bch_fs_usage *stats;
+       struct bch_fs_pcpu *pcpu;
        u64 old, v, get;
        s64 sectors_available;
        int ret;
 
-       percpu_down_read_preempt_disable(&c->usage_lock);
-       stats = this_cpu_ptr(c->usage_percpu);
+       percpu_down_read(&c->mark_lock);
+       preempt_disable();
+       pcpu = this_cpu_ptr(c->pcpu);
 
-       if (sectors <= stats->available_cache)
+       if (sectors <= pcpu->sectors_available)
                goto out;
 
        v = atomic64_read(&c->sectors_available);
@@ -746,198 +2016,122 @@ int bch2_disk_reservation_add(struct bch_fs *c, struct disk_reservation *res,
                get = min((u64) sectors + SECTORS_CACHE, old);
 
                if (get < sectors) {
-                       percpu_up_read_preempt_enable(&c->usage_lock);
+                       preempt_enable();
                        goto recalculate;
                }
        } while ((v = atomic64_cmpxchg(&c->sectors_available,
                                       old, old - get)) != old);
 
-       stats->available_cache  += get;
+       pcpu->sectors_available         += get;
 
 out:
-       stats->available_cache  -= sectors;
-       stats->online_reserved  += sectors;
-       res->sectors            += sectors;
+       pcpu->sectors_available         -= sectors;
+       this_cpu_add(*c->online_reserved, sectors);
+       res->sectors                    += sectors;
 
-       bch2_disk_reservations_verify(c, flags);
-       bch2_fs_stats_verify(c);
-       percpu_up_read_preempt_enable(&c->usage_lock);
+       preempt_enable();
+       percpu_up_read(&c->mark_lock);
        return 0;
 
 recalculate:
-       /*
-        * GC recalculates sectors_available when it starts, so that hopefully
-        * we don't normally end up blocking here:
-        */
-
-       /*
-        * Piss fuck, we can be called from extent_insert_fixup() with btree
-        * locks held:
-        */
-
-       if (!(flags & BCH_DISK_RESERVATION_GC_LOCK_HELD)) {
-               if (!(flags & BCH_DISK_RESERVATION_BTREE_LOCKS_HELD))
-                       down_read(&c->gc_lock);
-               else if (!down_read_trylock(&c->gc_lock))
-                       return -EINTR;
-       }
+       mutex_lock(&c->sectors_available_lock);
 
-       percpu_down_write(&c->usage_lock);
-       sectors_available = __recalc_sectors_available(c);
+       percpu_u64_set(&c->pcpu->sectors_available, 0);
+       sectors_available = avail_factor(__bch2_fs_usage_read_short(c).free);
 
        if (sectors <= sectors_available ||
            (flags & BCH_DISK_RESERVATION_NOFAIL)) {
                atomic64_set(&c->sectors_available,
                             max_t(s64, 0, sectors_available - sectors));
-               stats->online_reserved  += sectors;
-               res->sectors            += sectors;
+               this_cpu_add(*c->online_reserved, sectors);
+               res->sectors                    += sectors;
                ret = 0;
-
-               bch2_disk_reservations_verify(c, flags);
        } else {
                atomic64_set(&c->sectors_available, sectors_available);
-               ret = -ENOSPC;
+               ret = -BCH_ERR_ENOSPC_disk_reservation;
        }
 
-       bch2_fs_stats_verify(c);
-       percpu_up_write(&c->usage_lock);
-
-       if (!(flags & BCH_DISK_RESERVATION_GC_LOCK_HELD))
-               up_read(&c->gc_lock);
+       mutex_unlock(&c->sectors_available_lock);
+       percpu_up_read(&c->mark_lock);
 
        return ret;
 }
 
 /* Startup/shutdown: */
 
-static void buckets_free_rcu(struct rcu_head *rcu)
+static void bucket_gens_free_rcu(struct rcu_head *rcu)
 {
-       struct bucket_array *buckets =
-               container_of(rcu, struct bucket_array, rcu);
+       struct bucket_gens *buckets =
+               container_of(rcu, struct bucket_gens, rcu);
 
-       kvpfree(buckets,
-               sizeof(struct bucket_array) +
-               buckets->nbuckets * sizeof(struct bucket));
+       kvpfree(buckets, sizeof(*buckets) + buckets->nbuckets);
 }
 
 int bch2_dev_buckets_resize(struct bch_fs *c, struct bch_dev *ca, u64 nbuckets)
 {
-       struct bucket_array *buckets = NULL, *old_buckets = NULL;
-       unsigned long *buckets_dirty = NULL;
-       u8 *oldest_gens = NULL;
-       alloc_fifo      free[RESERVE_NR];
-       alloc_fifo      free_inc;
-       alloc_heap      alloc_heap;
-       copygc_heap     copygc_heap;
-
-       size_t btree_reserve    = DIV_ROUND_UP(BTREE_NODE_RESERVE,
-                            ca->mi.bucket_size / c->opts.btree_node_size);
-       /* XXX: these should be tunable */
-       size_t reserve_none     = max_t(size_t, 4, ca->mi.nbuckets >> 9);
-       size_t copygc_reserve   = max_t(size_t, 16, ca->mi.nbuckets >> 7);
-       size_t free_inc_reserve = copygc_reserve / 2;
-       bool resize = ca->buckets != NULL,
-            start_copygc = ca->copygc_thread != NULL;
-       int ret = -ENOMEM;
-       unsigned i;
+       struct bucket_gens *bucket_gens = NULL, *old_bucket_gens = NULL;
+       unsigned long *buckets_nouse = NULL;
+       bool resize = ca->bucket_gens != NULL;
+       int ret;
 
-       memset(&free,           0, sizeof(free));
-       memset(&free_inc,       0, sizeof(free_inc));
-       memset(&alloc_heap,     0, sizeof(alloc_heap));
-       memset(&copygc_heap,    0, sizeof(copygc_heap));
-
-       if (!(buckets           = kvpmalloc(sizeof(struct bucket_array) +
-                                           nbuckets * sizeof(struct bucket),
-                                           GFP_KERNEL|__GFP_ZERO)) ||
-           !(oldest_gens       = kvpmalloc(nbuckets * sizeof(u8),
-                                           GFP_KERNEL|__GFP_ZERO)) ||
-           !(buckets_dirty     = kvpmalloc(BITS_TO_LONGS(nbuckets) *
+       if (!(bucket_gens       = kvpmalloc(sizeof(struct bucket_gens) + nbuckets,
+                                           GFP_KERNEL|__GFP_ZERO))) {
+               ret = -BCH_ERR_ENOMEM_bucket_gens;
+               goto err;
+       }
+
+       if ((c->opts.buckets_nouse &&
+            !(buckets_nouse    = kvpmalloc(BITS_TO_LONGS(nbuckets) *
                                            sizeof(unsigned long),
-                                           GFP_KERNEL|__GFP_ZERO)) ||
-           !init_fifo(&free[RESERVE_BTREE], btree_reserve, GFP_KERNEL) ||
-           !init_fifo(&free[RESERVE_MOVINGGC],
-                      copygc_reserve, GFP_KERNEL) ||
-           !init_fifo(&free[RESERVE_NONE], reserve_none, GFP_KERNEL) ||
-           !init_fifo(&free_inc,       free_inc_reserve, GFP_KERNEL) ||
-           !init_heap(&alloc_heap,     free_inc_reserve, GFP_KERNEL) ||
-           !init_heap(&copygc_heap,    copygc_reserve, GFP_KERNEL))
+                                           GFP_KERNEL|__GFP_ZERO)))) {
+               ret = -BCH_ERR_ENOMEM_buckets_nouse;
                goto err;
+       }
 
-       buckets->first_bucket   = ca->mi.first_bucket;
-       buckets->nbuckets       = nbuckets;
+       bucket_gens->first_bucket = ca->mi.first_bucket;
+       bucket_gens->nbuckets   = nbuckets;
 
-       bch2_copygc_stop(ca);
+       bch2_copygc_stop(c);
 
        if (resize) {
                down_write(&c->gc_lock);
                down_write(&ca->bucket_lock);
-               percpu_down_write(&c->usage_lock);
+               percpu_down_write(&c->mark_lock);
        }
 
-       old_buckets = bucket_array(ca);
+       old_bucket_gens = rcu_dereference_protected(ca->bucket_gens, 1);
 
        if (resize) {
-               size_t n = min(buckets->nbuckets, old_buckets->nbuckets);
-
-               memcpy(buckets->b,
-                      old_buckets->b,
-                      n * sizeof(struct bucket));
-               memcpy(oldest_gens,
-                      ca->oldest_gens,
-                      n * sizeof(u8));
-               memcpy(buckets_dirty,
-                      ca->buckets_dirty,
-                      BITS_TO_LONGS(n) * sizeof(unsigned long));
+               size_t n = min(bucket_gens->nbuckets, old_bucket_gens->nbuckets);
+
+               memcpy(bucket_gens->b,
+                      old_bucket_gens->b,
+                      n);
+               if (buckets_nouse)
+                       memcpy(buckets_nouse,
+                              ca->buckets_nouse,
+                              BITS_TO_LONGS(n) * sizeof(unsigned long));
        }
 
-       rcu_assign_pointer(ca->buckets, buckets);
-       buckets = old_buckets;
-
-       swap(ca->oldest_gens, oldest_gens);
-       swap(ca->buckets_dirty, buckets_dirty);
+       rcu_assign_pointer(ca->bucket_gens, bucket_gens);
+       bucket_gens     = old_bucket_gens;
 
-       if (resize)
-               percpu_up_write(&c->usage_lock);
-
-       spin_lock(&c->freelist_lock);
-       for (i = 0; i < RESERVE_NR; i++) {
-               fifo_move(&free[i], &ca->free[i]);
-               swap(ca->free[i], free[i]);
-       }
-       fifo_move(&free_inc, &ca->free_inc);
-       swap(ca->free_inc, free_inc);
-       spin_unlock(&c->freelist_lock);
-
-       /* with gc lock held, alloc_heap can't be in use: */
-       swap(ca->alloc_heap, alloc_heap);
-
-       /* and we shut down copygc: */
-       swap(ca->copygc_heap, copygc_heap);
+       swap(ca->buckets_nouse, buckets_nouse);
 
        nbuckets = ca->mi.nbuckets;
 
        if (resize) {
+               percpu_up_write(&c->mark_lock);
                up_write(&ca->bucket_lock);
                up_write(&c->gc_lock);
        }
 
-       if (start_copygc &&
-           bch2_copygc_start(c, ca))
-               bch_err(ca, "error restarting copygc thread");
-
        ret = 0;
 err:
-       free_heap(&copygc_heap);
-       free_heap(&alloc_heap);
-       free_fifo(&free_inc);
-       for (i = 0; i < RESERVE_NR; i++)
-               free_fifo(&free[i]);
-       kvpfree(buckets_dirty,
+       kvpfree(buckets_nouse,
                BITS_TO_LONGS(nbuckets) * sizeof(unsigned long));
-       kvpfree(oldest_gens,
-               nbuckets * sizeof(u8));
-       if (buckets)
-               call_rcu(&old_buckets->rcu, buckets_free_rcu);
+       if (bucket_gens)
+               call_rcu(&bucket_gens->rcu, bucket_gens_free_rcu);
 
        return ret;
 }
@@ -946,25 +2140,29 @@ void bch2_dev_buckets_free(struct bch_dev *ca)
 {
        unsigned i;
 
-       free_heap(&ca->copygc_heap);
-       free_heap(&ca->alloc_heap);
-       free_fifo(&ca->free_inc);
-       for (i = 0; i < RESERVE_NR; i++)
-               free_fifo(&ca->free[i]);
-       kvpfree(ca->buckets_dirty,
+       kvpfree(ca->buckets_nouse,
                BITS_TO_LONGS(ca->mi.nbuckets) * sizeof(unsigned long));
-       kvpfree(ca->oldest_gens, ca->mi.nbuckets * sizeof(u8));
-       kvpfree(rcu_dereference_protected(ca->buckets, 1),
-               sizeof(struct bucket_array) +
-               ca->mi.nbuckets * sizeof(struct bucket));
+       kvpfree(rcu_dereference_protected(ca->bucket_gens, 1),
+               sizeof(struct bucket_gens) + ca->mi.nbuckets);
 
-       free_percpu(ca->usage_percpu);
+       for (i = 0; i < ARRAY_SIZE(ca->usage); i++)
+               free_percpu(ca->usage[i]);
+       kfree(ca->usage_base);
 }
 
 int bch2_dev_buckets_alloc(struct bch_fs *c, struct bch_dev *ca)
 {
-       if (!(ca->usage_percpu = alloc_percpu(struct bch_dev_usage)))
-               return -ENOMEM;
+       unsigned i;
+
+       ca->usage_base = kzalloc(sizeof(struct bch_dev_usage), GFP_KERNEL);
+       if (!ca->usage_base)
+               return -BCH_ERR_ENOMEM_usage_init;
+
+       for (i = 0; i < ARRAY_SIZE(ca->usage); i++) {
+               ca->usage[i] = alloc_percpu(struct bch_dev_usage);
+               if (!ca->usage[i])
+                       return -BCH_ERR_ENOMEM_usage_init;
+       }
 
-       return bch2_dev_buckets_resize(c, ca, ca->mi.nbuckets);;
+       return bch2_dev_buckets_resize(c, ca, ca->mi.nbuckets);
 }