]> git.sesse.net Git - bcachefs-tools-debian/blobdiff - c_src/libbcachefs/ec.c
move Rust sources to top level, C sources into c_src
[bcachefs-tools-debian] / c_src / libbcachefs / ec.c
diff --git a/c_src/libbcachefs/ec.c b/c_src/libbcachefs/ec.c
new file mode 100644 (file)
index 0000000..d802bc6
--- /dev/null
@@ -0,0 +1,2259 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/* erasure coding */
+
+#include "bcachefs.h"
+#include "alloc_background.h"
+#include "alloc_foreground.h"
+#include "backpointers.h"
+#include "bkey_buf.h"
+#include "bset.h"
+#include "btree_gc.h"
+#include "btree_update.h"
+#include "btree_write_buffer.h"
+#include "buckets.h"
+#include "checksum.h"
+#include "disk_groups.h"
+#include "ec.h"
+#include "error.h"
+#include "io_read.h"
+#include "keylist.h"
+#include "recovery.h"
+#include "replicas.h"
+#include "super-io.h"
+#include "util.h"
+
+#include <linux/sort.h>
+
+#ifdef __KERNEL__
+
+#include <linux/raid/pq.h>
+#include <linux/raid/xor.h>
+
+static void raid5_recov(unsigned disks, unsigned failed_idx,
+                       size_t size, void **data)
+{
+       unsigned i = 2, nr;
+
+       BUG_ON(failed_idx >= disks);
+
+       swap(data[0], data[failed_idx]);
+       memcpy(data[0], data[1], size);
+
+       while (i < disks) {
+               nr = min_t(unsigned, disks - i, MAX_XOR_BLOCKS);
+               xor_blocks(nr, size, data[0], data + i);
+               i += nr;
+       }
+
+       swap(data[0], data[failed_idx]);
+}
+
+static void raid_gen(int nd, int np, size_t size, void **v)
+{
+       if (np >= 1)
+               raid5_recov(nd + np, nd, size, v);
+       if (np >= 2)
+               raid6_call.gen_syndrome(nd + np, size, v);
+       BUG_ON(np > 2);
+}
+
+static void raid_rec(int nr, int *ir, int nd, int np, size_t size, void **v)
+{
+       switch (nr) {
+       case 0:
+               break;
+       case 1:
+               if (ir[0] < nd + 1)
+                       raid5_recov(nd + 1, ir[0], size, v);
+               else
+                       raid6_call.gen_syndrome(nd + np, size, v);
+               break;
+       case 2:
+               if (ir[1] < nd) {
+                       /* data+data failure. */
+                       raid6_2data_recov(nd + np, size, ir[0], ir[1], v);
+               } else if (ir[0] < nd) {
+                       /* data + p/q failure */
+
+                       if (ir[1] == nd) /* data + p failure */
+                               raid6_datap_recov(nd + np, size, ir[0], v);
+                       else { /* data + q failure */
+                               raid5_recov(nd + 1, ir[0], size, v);
+                               raid6_call.gen_syndrome(nd + np, size, v);
+                       }
+               } else {
+                       raid_gen(nd, np, size, v);
+               }
+               break;
+       default:
+               BUG();
+       }
+}
+
+#else
+
+#include <raid/raid.h>
+
+#endif
+
+struct ec_bio {
+       struct bch_dev          *ca;
+       struct ec_stripe_buf    *buf;
+       size_t                  idx;
+       struct bio              bio;
+};
+
+/* Stripes btree keys: */
+
+int bch2_stripe_invalid(struct bch_fs *c, struct bkey_s_c k,
+                       enum bkey_invalid_flags flags,
+                       struct printbuf *err)
+{
+       const struct bch_stripe *s = bkey_s_c_to_stripe(k).v;
+       int ret = 0;
+
+       bkey_fsck_err_on(bkey_eq(k.k->p, POS_MIN) ||
+                        bpos_gt(k.k->p, POS(0, U32_MAX)), c, err,
+                        stripe_pos_bad,
+                        "stripe at bad pos");
+
+       bkey_fsck_err_on(bkey_val_u64s(k.k) < stripe_val_u64s(s), c, err,
+                        stripe_val_size_bad,
+                        "incorrect value size (%zu < %u)",
+                        bkey_val_u64s(k.k), stripe_val_u64s(s));
+
+       ret = bch2_bkey_ptrs_invalid(c, k, flags, err);
+fsck_err:
+       return ret;
+}
+
+void bch2_stripe_to_text(struct printbuf *out, struct bch_fs *c,
+                        struct bkey_s_c k)
+{
+       const struct bch_stripe *s = bkey_s_c_to_stripe(k).v;
+       unsigned i, nr_data = s->nr_blocks - s->nr_redundant;
+
+       prt_printf(out, "algo %u sectors %u blocks %u:%u csum %u gran %u",
+              s->algorithm,
+              le16_to_cpu(s->sectors),
+              nr_data,
+              s->nr_redundant,
+              s->csum_type,
+              1U << s->csum_granularity_bits);
+
+       for (i = 0; i < s->nr_blocks; i++) {
+               const struct bch_extent_ptr *ptr = s->ptrs + i;
+               struct bch_dev *ca = bch_dev_bkey_exists(c, ptr->dev);
+               u32 offset;
+               u64 b = sector_to_bucket_and_offset(ca, ptr->offset, &offset);
+
+               prt_printf(out, " %u:%llu:%u", ptr->dev, b, offset);
+               if (i < nr_data)
+                       prt_printf(out, "#%u", stripe_blockcount_get(s, i));
+               prt_printf(out, " gen %u", ptr->gen);
+               if (ptr_stale(ca, ptr))
+                       prt_printf(out, " stale");
+       }
+}
+
+/* Triggers: */
+
+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 = bch2_check_bucket_ref(trans, s.s_c, ptr, sectors, data_type,
+                                   a->v.gen, a->v.data_type,
+                                   a->v.dirty_sectors);
+       if (ret)
+               goto err;
+
+       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;
+               }
+
+               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;
+}
+
+static int mark_stripe_bucket(struct btree_trans *trans,
+                             struct bkey_s_c k,
+                             unsigned ptr_idx,
+                             unsigned flags)
+{
+       struct bch_fs *c = trans->c;
+       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));
+
+       /* * XXX doesn't handle deletion */
+
+       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,
+                             "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;
+       }
+
+       bucket_lock(g);
+       old = *g;
+
+       ret = bch2_check_bucket_ref(trans, k, ptr, sectors, data_type,
+                                   g->gen, g->data_type,
+                                   g->dirty_sectors);
+       if (ret)
+               goto err;
+
+       g->data_type = data_type;
+       g->dirty_sectors += sectors;
+
+       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);
+       percpu_up_read(&c->mark_lock);
+       printbuf_exit(&buf);
+       return ret;
+}
+
+int bch2_trigger_stripe(struct btree_trans *trans,
+                       enum btree_id btree_id, unsigned level,
+                       struct bkey_s_c old, struct bkey_s _new,
+                       unsigned flags)
+{
+       struct bkey_s_c new = _new.s_c;
+       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;
+
+       if (flags & BTREE_TRIGGER_TRANSACTIONAL) {
+               /*
+                * 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));
+
+               if (new_s) {
+                       s64 sectors = le16_to_cpu(new_s->sectors);
+
+                       struct bch_replicas_padded r;
+                       bch2_bkey_to_replicas(&r.e, new);
+                       int ret = bch2_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));
+
+                       struct bch_replicas_padded r;
+                       bch2_bkey_to_replicas(&r.e, old);
+                       int ret = bch2_update_replicas_list(trans, &r.e, sectors * old_s->nr_redundant);
+                       if (ret)
+                               return ret;
+               }
+
+               unsigned nr_blocks = new_s ? new_s->nr_blocks : old_s->nr_blocks;
+               for (unsigned 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) {
+                               int ret = bch2_trans_mark_stripe_bucket(trans,
+                                               bkey_s_c_to_stripe(new), i, false);
+                               if (ret)
+                                       return ret;
+                       }
+
+                       if (old_s) {
+                               int ret = bch2_trans_mark_stripe_bucket(trans,
+                                               bkey_s_c_to_stripe(old), i, true);
+                               if (ret)
+                                       return ret;
+                       }
+               }
+       }
+
+       if (!(flags & (BTREE_TRIGGER_TRANSACTIONAL|BTREE_TRIGGER_GC))) {
+               struct stripe *m = genradix_ptr(&c->stripes, idx);
+
+               if (!m) {
+                       struct printbuf buf1 = PRINTBUF;
+                       struct printbuf buf2 = PRINTBUF;
+
+                       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 (unsigned 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);
+               }
+       }
+
+       if (flags & BTREE_TRIGGER_GC) {
+               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 (unsigned i = 0; i < new_s->nr_blocks; i++)
+                       m->ptrs[i] = new_s->ptrs[i];
+
+               bch2_bkey_to_replicas(&m->r.e, new);
+
+               /*
+                * gc recalculates this field from stripe ptr
+                * references:
+                */
+               memset(m->block_sectors, 0, sizeof(m->block_sectors));
+
+               for (unsigned i = 0; i < new_s->nr_blocks; i++) {
+                       int ret = mark_stripe_bucket(trans, new, i, flags);
+                       if (ret)
+                               return ret;
+               }
+
+               int ret = bch2_update_replicas(c, new, &m->r.e,
+                                     ((s64) m->sectors * m->nr_redundant),
+                                     0, true);
+               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;
+               }
+       }
+
+       return 0;
+}
+
+/* returns blocknr in stripe that we matched: */
+static const struct bch_extent_ptr *bkey_matches_stripe(struct bch_stripe *s,
+                                               struct bkey_s_c k, unsigned *block)
+{
+       struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
+       unsigned i, nr_data = s->nr_blocks - s->nr_redundant;
+
+       bkey_for_each_ptr(ptrs, ptr)
+               for (i = 0; i < nr_data; i++)
+                       if (__bch2_ptr_matches_stripe(&s->ptrs[i], ptr,
+                                                     le16_to_cpu(s->sectors))) {
+                               *block = i;
+                               return ptr;
+                       }
+
+       return NULL;
+}
+
+static bool extent_has_stripe_ptr(struct bkey_s_c k, u64 idx)
+{
+       switch (k.k->type) {
+       case KEY_TYPE_extent: {
+               struct bkey_s_c_extent e = bkey_s_c_to_extent(k);
+               const union bch_extent_entry *entry;
+
+               extent_for_each_entry(e, entry)
+                       if (extent_entry_type(entry) ==
+                           BCH_EXTENT_ENTRY_stripe_ptr &&
+                           entry->stripe_ptr.idx == idx)
+                               return true;
+
+               break;
+       }
+       }
+
+       return false;
+}
+
+/* Stripe bufs: */
+
+static void ec_stripe_buf_exit(struct ec_stripe_buf *buf)
+{
+       if (buf->key.k.type == KEY_TYPE_stripe) {
+               struct bkey_i_stripe *s = bkey_i_to_stripe(&buf->key);
+               unsigned i;
+
+               for (i = 0; i < s->v.nr_blocks; i++) {
+                       kvpfree(buf->data[i], buf->size << 9);
+                       buf->data[i] = NULL;
+               }
+       }
+}
+
+/* XXX: this is a non-mempoolified memory allocation: */
+static int ec_stripe_buf_init(struct ec_stripe_buf *buf,
+                             unsigned offset, unsigned size)
+{
+       struct bch_stripe *v = &bkey_i_to_stripe(&buf->key)->v;
+       unsigned csum_granularity = 1U << v->csum_granularity_bits;
+       unsigned end = offset + size;
+       unsigned i;
+
+       BUG_ON(end > le16_to_cpu(v->sectors));
+
+       offset  = round_down(offset, csum_granularity);
+       end     = min_t(unsigned, le16_to_cpu(v->sectors),
+                       round_up(end, csum_granularity));
+
+       buf->offset     = offset;
+       buf->size       = end - offset;
+
+       memset(buf->valid, 0xFF, sizeof(buf->valid));
+
+       for (i = 0; i < v->nr_blocks; i++) {
+               buf->data[i] = kvpmalloc(buf->size << 9, GFP_KERNEL);
+               if (!buf->data[i])
+                       goto err;
+       }
+
+       return 0;
+err:
+       ec_stripe_buf_exit(buf);
+       return -BCH_ERR_ENOMEM_stripe_buf;
+}
+
+/* Checksumming: */
+
+static struct bch_csum ec_block_checksum(struct ec_stripe_buf *buf,
+                                        unsigned block, unsigned offset)
+{
+       struct bch_stripe *v = &bkey_i_to_stripe(&buf->key)->v;
+       unsigned csum_granularity = 1 << v->csum_granularity_bits;
+       unsigned end = buf->offset + buf->size;
+       unsigned len = min(csum_granularity, end - offset);
+
+       BUG_ON(offset >= end);
+       BUG_ON(offset <  buf->offset);
+       BUG_ON(offset & (csum_granularity - 1));
+       BUG_ON(offset + len != le16_to_cpu(v->sectors) &&
+              (len & (csum_granularity - 1)));
+
+       return bch2_checksum(NULL, v->csum_type,
+                            null_nonce(),
+                            buf->data[block] + ((offset - buf->offset) << 9),
+                            len << 9);
+}
+
+static void ec_generate_checksums(struct ec_stripe_buf *buf)
+{
+       struct bch_stripe *v = &bkey_i_to_stripe(&buf->key)->v;
+       unsigned i, j, csums_per_device = stripe_csums_per_device(v);
+
+       if (!v->csum_type)
+               return;
+
+       BUG_ON(buf->offset);
+       BUG_ON(buf->size != le16_to_cpu(v->sectors));
+
+       for (i = 0; i < v->nr_blocks; i++)
+               for (j = 0; j < csums_per_device; j++)
+                       stripe_csum_set(v, i, j,
+                               ec_block_checksum(buf, i, j << v->csum_granularity_bits));
+}
+
+static void ec_validate_checksums(struct bch_fs *c, struct ec_stripe_buf *buf)
+{
+       struct bch_stripe *v = &bkey_i_to_stripe(&buf->key)->v;
+       unsigned csum_granularity = 1 << v->csum_granularity_bits;
+       unsigned i;
+
+       if (!v->csum_type)
+               return;
+
+       for (i = 0; i < v->nr_blocks; i++) {
+               unsigned offset = buf->offset;
+               unsigned end = buf->offset + buf->size;
+
+               if (!test_bit(i, buf->valid))
+                       continue;
+
+               while (offset < end) {
+                       unsigned j = offset >> v->csum_granularity_bits;
+                       unsigned len = min(csum_granularity, end - offset);
+                       struct bch_csum want = stripe_csum_get(v, i, j);
+                       struct bch_csum got = ec_block_checksum(buf, i, offset);
+
+                       if (bch2_crc_cmp(want, got)) {
+                               struct printbuf err = PRINTBUF;
+                               struct bch_dev *ca = bch_dev_bkey_exists(c, v->ptrs[i].dev);
+
+                               prt_printf(&err, "stripe checksum error: expected %0llx:%0llx got %0llx:%0llx (type %s)\n",
+                                          want.hi, want.lo,
+                                          got.hi, got.lo,
+                                          bch2_csum_types[v->csum_type]);
+                               prt_printf(&err, "  for %ps at %u of\n  ", (void *) _RET_IP_, i);
+                               bch2_bkey_val_to_text(&err, c, bkey_i_to_s_c(&buf->key));
+                               bch_err_ratelimited(ca, "%s", err.buf);
+                               printbuf_exit(&err);
+
+                               clear_bit(i, buf->valid);
+
+                               bch2_io_error(ca, BCH_MEMBER_ERROR_checksum);
+                               break;
+                       }
+
+                       offset += len;
+               }
+       }
+}
+
+/* Erasure coding: */
+
+static void ec_generate_ec(struct ec_stripe_buf *buf)
+{
+       struct bch_stripe *v = &bkey_i_to_stripe(&buf->key)->v;
+       unsigned nr_data = v->nr_blocks - v->nr_redundant;
+       unsigned bytes = le16_to_cpu(v->sectors) << 9;
+
+       raid_gen(nr_data, v->nr_redundant, bytes, buf->data);
+}
+
+static unsigned ec_nr_failed(struct ec_stripe_buf *buf)
+{
+       struct bch_stripe *v = &bkey_i_to_stripe(&buf->key)->v;
+
+       return v->nr_blocks - bitmap_weight(buf->valid, v->nr_blocks);
+}
+
+static int ec_do_recov(struct bch_fs *c, struct ec_stripe_buf *buf)
+{
+       struct bch_stripe *v = &bkey_i_to_stripe(&buf->key)->v;
+       unsigned i, failed[BCH_BKEY_PTRS_MAX], nr_failed = 0;
+       unsigned nr_data = v->nr_blocks - v->nr_redundant;
+       unsigned bytes = buf->size << 9;
+
+       if (ec_nr_failed(buf) > v->nr_redundant) {
+               bch_err_ratelimited(c,
+                       "error doing reconstruct read: unable to read enough blocks");
+               return -1;
+       }
+
+       for (i = 0; i < nr_data; i++)
+               if (!test_bit(i, buf->valid))
+                       failed[nr_failed++] = i;
+
+       raid_rec(nr_failed, failed, nr_data, v->nr_redundant, bytes, buf->data);
+       return 0;
+}
+
+/* IO: */
+
+static void ec_block_endio(struct bio *bio)
+{
+       struct ec_bio *ec_bio = container_of(bio, struct ec_bio, bio);
+       struct bch_stripe *v = &bkey_i_to_stripe(&ec_bio->buf->key)->v;
+       struct bch_extent_ptr *ptr = &v->ptrs[ec_bio->idx];
+       struct bch_dev *ca = ec_bio->ca;
+       struct closure *cl = bio->bi_private;
+
+       if (bch2_dev_io_err_on(bio->bi_status, ca,
+                              bio_data_dir(bio)
+                              ? BCH_MEMBER_ERROR_write
+                              : BCH_MEMBER_ERROR_read,
+                              "erasure coding %s error: %s",
+                              bio_data_dir(bio) ? "write" : "read",
+                              bch2_blk_status_to_str(bio->bi_status)))
+               clear_bit(ec_bio->idx, ec_bio->buf->valid);
+
+       if (ptr_stale(ca, ptr)) {
+               bch_err_ratelimited(ca->fs,
+                                   "error %s stripe: stale pointer after io",
+                                   bio_data_dir(bio) == READ ? "reading from" : "writing to");
+               clear_bit(ec_bio->idx, ec_bio->buf->valid);
+       }
+
+       bio_put(&ec_bio->bio);
+       percpu_ref_put(&ca->io_ref);
+       closure_put(cl);
+}
+
+static void ec_block_io(struct bch_fs *c, struct ec_stripe_buf *buf,
+                       blk_opf_t opf, unsigned idx, struct closure *cl)
+{
+       struct bch_stripe *v = &bkey_i_to_stripe(&buf->key)->v;
+       unsigned offset = 0, bytes = buf->size << 9;
+       struct bch_extent_ptr *ptr = &v->ptrs[idx];
+       struct bch_dev *ca = bch_dev_bkey_exists(c, ptr->dev);
+       enum bch_data_type data_type = idx < v->nr_blocks - v->nr_redundant
+               ? BCH_DATA_user
+               : BCH_DATA_parity;
+       int rw = op_is_write(opf);
+
+       if (ptr_stale(ca, ptr)) {
+               bch_err_ratelimited(c,
+                                   "error %s stripe: stale pointer",
+                                   rw == READ ? "reading from" : "writing to");
+               clear_bit(idx, buf->valid);
+               return;
+       }
+
+       if (!bch2_dev_get_ioref(ca, rw)) {
+               clear_bit(idx, buf->valid);
+               return;
+       }
+
+       this_cpu_add(ca->io_done->sectors[rw][data_type], buf->size);
+
+       while (offset < bytes) {
+               unsigned nr_iovecs = min_t(size_t, BIO_MAX_VECS,
+                                          DIV_ROUND_UP(bytes, PAGE_SIZE));
+               unsigned b = min_t(size_t, bytes - offset,
+                                  nr_iovecs << PAGE_SHIFT);
+               struct ec_bio *ec_bio;
+
+               ec_bio = container_of(bio_alloc_bioset(ca->disk_sb.bdev,
+                                                      nr_iovecs,
+                                                      opf,
+                                                      GFP_KERNEL,
+                                                      &c->ec_bioset),
+                                     struct ec_bio, bio);
+
+               ec_bio->ca                      = ca;
+               ec_bio->buf                     = buf;
+               ec_bio->idx                     = idx;
+
+               ec_bio->bio.bi_iter.bi_sector   = ptr->offset + buf->offset + (offset >> 9);
+               ec_bio->bio.bi_end_io           = ec_block_endio;
+               ec_bio->bio.bi_private          = cl;
+
+               bch2_bio_map(&ec_bio->bio, buf->data[idx] + offset, b);
+
+               closure_get(cl);
+               percpu_ref_get(&ca->io_ref);
+
+               submit_bio(&ec_bio->bio);
+
+               offset += b;
+       }
+
+       percpu_ref_put(&ca->io_ref);
+}
+
+static int get_stripe_key_trans(struct btree_trans *trans, u64 idx,
+                               struct ec_stripe_buf *stripe)
+{
+       struct btree_iter iter;
+       struct bkey_s_c k;
+       int ret;
+
+       k = bch2_bkey_get_iter(trans, &iter, BTREE_ID_stripes,
+                              POS(0, idx), BTREE_ITER_SLOTS);
+       ret = bkey_err(k);
+       if (ret)
+               goto err;
+       if (k.k->type != KEY_TYPE_stripe) {
+               ret = -ENOENT;
+               goto err;
+       }
+       bkey_reassemble(&stripe->key, k);
+err:
+       bch2_trans_iter_exit(trans, &iter);
+       return ret;
+}
+
+/* recovery read path: */
+int bch2_ec_read_extent(struct btree_trans *trans, struct bch_read_bio *rbio)
+{
+       struct bch_fs *c = trans->c;
+       struct ec_stripe_buf *buf;
+       struct closure cl;
+       struct bch_stripe *v;
+       unsigned i, offset;
+       int ret = 0;
+
+       closure_init_stack(&cl);
+
+       BUG_ON(!rbio->pick.has_ec);
+
+       buf = kzalloc(sizeof(*buf), GFP_NOFS);
+       if (!buf)
+               return -BCH_ERR_ENOMEM_ec_read_extent;
+
+       ret = lockrestart_do(trans, get_stripe_key_trans(trans, rbio->pick.ec.idx, buf));
+       if (ret) {
+               bch_err_ratelimited(c,
+                       "error doing reconstruct read: error %i looking up stripe", ret);
+               kfree(buf);
+               return -EIO;
+       }
+
+       v = &bkey_i_to_stripe(&buf->key)->v;
+
+       if (!bch2_ptr_matches_stripe(v, rbio->pick)) {
+               bch_err_ratelimited(c,
+                       "error doing reconstruct read: pointer doesn't match stripe");
+               ret = -EIO;
+               goto err;
+       }
+
+       offset = rbio->bio.bi_iter.bi_sector - v->ptrs[rbio->pick.ec.block].offset;
+       if (offset + bio_sectors(&rbio->bio) > le16_to_cpu(v->sectors)) {
+               bch_err_ratelimited(c,
+                       "error doing reconstruct read: read is bigger than stripe");
+               ret = -EIO;
+               goto err;
+       }
+
+       ret = ec_stripe_buf_init(buf, offset, bio_sectors(&rbio->bio));
+       if (ret)
+               goto err;
+
+       for (i = 0; i < v->nr_blocks; i++)
+               ec_block_io(c, buf, REQ_OP_READ, i, &cl);
+
+       closure_sync(&cl);
+
+       if (ec_nr_failed(buf) > v->nr_redundant) {
+               bch_err_ratelimited(c,
+                       "error doing reconstruct read: unable to read enough blocks");
+               ret = -EIO;
+               goto err;
+       }
+
+       ec_validate_checksums(c, buf);
+
+       ret = ec_do_recov(c, buf);
+       if (ret)
+               goto err;
+
+       memcpy_to_bio(&rbio->bio, rbio->bio.bi_iter,
+                     buf->data[rbio->pick.ec.block] + ((offset - buf->offset) << 9));
+err:
+       ec_stripe_buf_exit(buf);
+       kfree(buf);
+       return ret;
+}
+
+/* stripe bucket accounting: */
+
+static int __ec_stripe_mem_alloc(struct bch_fs *c, size_t idx, gfp_t gfp)
+{
+       ec_stripes_heap n, *h = &c->ec_stripes_heap;
+
+       if (idx >= h->size) {
+               if (!init_heap(&n, max(1024UL, roundup_pow_of_two(idx + 1)), gfp))
+                       return -BCH_ERR_ENOMEM_ec_stripe_mem_alloc;
+
+               mutex_lock(&c->ec_stripes_heap_lock);
+               if (n.size > h->size) {
+                       memcpy(n.data, h->data, h->used * sizeof(h->data[0]));
+                       n.used = h->used;
+                       swap(*h, n);
+               }
+               mutex_unlock(&c->ec_stripes_heap_lock);
+
+               free_heap(&n);
+       }
+
+       if (!genradix_ptr_alloc(&c->stripes, idx, gfp))
+               return -BCH_ERR_ENOMEM_ec_stripe_mem_alloc;
+
+       if (c->gc_pos.phase != GC_PHASE_NOT_RUNNING &&
+           !genradix_ptr_alloc(&c->gc_stripes, idx, gfp))
+               return -BCH_ERR_ENOMEM_ec_stripe_mem_alloc;
+
+       return 0;
+}
+
+static int ec_stripe_mem_alloc(struct btree_trans *trans,
+                              struct btree_iter *iter)
+{
+       return allocate_dropping_locks_errcode(trans,
+                       __ec_stripe_mem_alloc(trans->c, iter->pos.offset, _gfp));
+}
+
+/*
+ * Hash table of open stripes:
+ * Stripes that are being created or modified are kept in a hash table, so that
+ * stripe deletion can skip them.
+ */
+
+static bool __bch2_stripe_is_open(struct bch_fs *c, u64 idx)
+{
+       unsigned hash = hash_64(idx, ilog2(ARRAY_SIZE(c->ec_stripes_new)));
+       struct ec_stripe_new *s;
+
+       hlist_for_each_entry(s, &c->ec_stripes_new[hash], hash)
+               if (s->idx == idx)
+                       return true;
+       return false;
+}
+
+static bool bch2_stripe_is_open(struct bch_fs *c, u64 idx)
+{
+       bool ret = false;
+
+       spin_lock(&c->ec_stripes_new_lock);
+       ret = __bch2_stripe_is_open(c, idx);
+       spin_unlock(&c->ec_stripes_new_lock);
+
+       return ret;
+}
+
+static bool bch2_try_open_stripe(struct bch_fs *c,
+                                struct ec_stripe_new *s,
+                                u64 idx)
+{
+       bool ret;
+
+       spin_lock(&c->ec_stripes_new_lock);
+       ret = !__bch2_stripe_is_open(c, idx);
+       if (ret) {
+               unsigned hash = hash_64(idx, ilog2(ARRAY_SIZE(c->ec_stripes_new)));
+
+               s->idx = idx;
+               hlist_add_head(&s->hash, &c->ec_stripes_new[hash]);
+       }
+       spin_unlock(&c->ec_stripes_new_lock);
+
+       return ret;
+}
+
+static void bch2_stripe_close(struct bch_fs *c, struct ec_stripe_new *s)
+{
+       BUG_ON(!s->idx);
+
+       spin_lock(&c->ec_stripes_new_lock);
+       hlist_del_init(&s->hash);
+       spin_unlock(&c->ec_stripes_new_lock);
+
+       s->idx = 0;
+}
+
+/* Heap of all existing stripes, ordered by blocks_nonempty */
+
+static u64 stripe_idx_to_delete(struct bch_fs *c)
+{
+       ec_stripes_heap *h = &c->ec_stripes_heap;
+
+       lockdep_assert_held(&c->ec_stripes_heap_lock);
+
+       if (h->used &&
+           h->data[0].blocks_nonempty == 0 &&
+           !bch2_stripe_is_open(c, h->data[0].idx))
+               return h->data[0].idx;
+
+       return 0;
+}
+
+static inline int ec_stripes_heap_cmp(ec_stripes_heap *h,
+                                     struct ec_stripe_heap_entry l,
+                                     struct ec_stripe_heap_entry r)
+{
+       return ((l.blocks_nonempty > r.blocks_nonempty) -
+               (l.blocks_nonempty < r.blocks_nonempty));
+}
+
+static inline void ec_stripes_heap_set_backpointer(ec_stripes_heap *h,
+                                                  size_t i)
+{
+       struct bch_fs *c = container_of(h, struct bch_fs, ec_stripes_heap);
+
+       genradix_ptr(&c->stripes, h->data[i].idx)->heap_idx = i;
+}
+
+static void heap_verify_backpointer(struct bch_fs *c, size_t idx)
+{
+       ec_stripes_heap *h = &c->ec_stripes_heap;
+       struct stripe *m = genradix_ptr(&c->stripes, idx);
+
+       BUG_ON(m->heap_idx >= h->used);
+       BUG_ON(h->data[m->heap_idx].idx != idx);
+}
+
+void bch2_stripes_heap_del(struct bch_fs *c,
+                          struct stripe *m, size_t idx)
+{
+       mutex_lock(&c->ec_stripes_heap_lock);
+       heap_verify_backpointer(c, idx);
+
+       heap_del(&c->ec_stripes_heap, m->heap_idx,
+                ec_stripes_heap_cmp,
+                ec_stripes_heap_set_backpointer);
+       mutex_unlock(&c->ec_stripes_heap_lock);
+}
+
+void bch2_stripes_heap_insert(struct bch_fs *c,
+                             struct stripe *m, size_t idx)
+{
+       mutex_lock(&c->ec_stripes_heap_lock);
+       BUG_ON(heap_full(&c->ec_stripes_heap));
+
+       heap_add(&c->ec_stripes_heap, ((struct ec_stripe_heap_entry) {
+                       .idx = idx,
+                       .blocks_nonempty = m->blocks_nonempty,
+               }),
+                ec_stripes_heap_cmp,
+                ec_stripes_heap_set_backpointer);
+
+       heap_verify_backpointer(c, idx);
+       mutex_unlock(&c->ec_stripes_heap_lock);
+}
+
+void bch2_stripes_heap_update(struct bch_fs *c,
+                             struct stripe *m, size_t idx)
+{
+       ec_stripes_heap *h = &c->ec_stripes_heap;
+       bool do_deletes;
+       size_t i;
+
+       mutex_lock(&c->ec_stripes_heap_lock);
+       heap_verify_backpointer(c, idx);
+
+       h->data[m->heap_idx].blocks_nonempty = m->blocks_nonempty;
+
+       i = m->heap_idx;
+       heap_sift_up(h,   i, ec_stripes_heap_cmp,
+                    ec_stripes_heap_set_backpointer);
+       heap_sift_down(h, i, ec_stripes_heap_cmp,
+                      ec_stripes_heap_set_backpointer);
+
+       heap_verify_backpointer(c, idx);
+
+       do_deletes = stripe_idx_to_delete(c) != 0;
+       mutex_unlock(&c->ec_stripes_heap_lock);
+
+       if (do_deletes)
+               bch2_do_stripe_deletes(c);
+}
+
+/* stripe deletion */
+
+static int ec_stripe_delete(struct btree_trans *trans, u64 idx)
+{
+       struct bch_fs *c = trans->c;
+       struct btree_iter iter;
+       struct bkey_s_c k;
+       struct bkey_s_c_stripe s;
+       int ret;
+
+       k = bch2_bkey_get_iter(trans, &iter, BTREE_ID_stripes, POS(0, idx),
+                              BTREE_ITER_INTENT);
+       ret = bkey_err(k);
+       if (ret)
+               goto err;
+
+       if (k.k->type != KEY_TYPE_stripe) {
+               bch2_fs_inconsistent(c, "attempting to delete nonexistent stripe %llu", idx);
+               ret = -EINVAL;
+               goto err;
+       }
+
+       s = bkey_s_c_to_stripe(k);
+       for (unsigned i = 0; i < s.v->nr_blocks; i++)
+               if (stripe_blockcount_get(s.v, i)) {
+                       struct printbuf buf = PRINTBUF;
+
+                       bch2_bkey_val_to_text(&buf, c, k);
+                       bch2_fs_inconsistent(c, "attempting to delete nonempty stripe %s", buf.buf);
+                       printbuf_exit(&buf);
+                       ret = -EINVAL;
+                       goto err;
+               }
+
+       ret = bch2_btree_delete_at(trans, &iter, 0);
+err:
+       bch2_trans_iter_exit(trans, &iter);
+       return ret;
+}
+
+static void ec_stripe_delete_work(struct work_struct *work)
+{
+       struct bch_fs *c =
+               container_of(work, struct bch_fs, ec_stripe_delete_work);
+
+       while (1) {
+               mutex_lock(&c->ec_stripes_heap_lock);
+               u64 idx = stripe_idx_to_delete(c);
+               mutex_unlock(&c->ec_stripes_heap_lock);
+
+               if (!idx)
+                       break;
+
+               int ret = bch2_trans_do(c, NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
+                                       ec_stripe_delete(trans, idx));
+               bch_err_fn(c, ret);
+               if (ret)
+                       break;
+       }
+
+       bch2_write_ref_put(c, BCH_WRITE_REF_stripe_delete);
+}
+
+void bch2_do_stripe_deletes(struct bch_fs *c)
+{
+       if (bch2_write_ref_tryget(c, BCH_WRITE_REF_stripe_delete) &&
+           !queue_work(c->write_ref_wq, &c->ec_stripe_delete_work))
+               bch2_write_ref_put(c, BCH_WRITE_REF_stripe_delete);
+}
+
+/* stripe creation: */
+
+static int ec_stripe_key_update(struct btree_trans *trans,
+                               struct bkey_i_stripe *new,
+                               bool create)
+{
+       struct bch_fs *c = trans->c;
+       struct btree_iter iter;
+       struct bkey_s_c k;
+       int ret;
+
+       k = bch2_bkey_get_iter(trans, &iter, BTREE_ID_stripes,
+                              new->k.p, BTREE_ITER_INTENT);
+       ret = bkey_err(k);
+       if (ret)
+               goto err;
+
+       if (k.k->type != (create ? KEY_TYPE_deleted : KEY_TYPE_stripe)) {
+               bch2_fs_inconsistent(c, "error %s stripe: got existing key type %s",
+                                    create ? "creating" : "updating",
+                                    bch2_bkey_types[k.k->type]);
+               ret = -EINVAL;
+               goto err;
+       }
+
+       if (k.k->type == KEY_TYPE_stripe) {
+               const struct bch_stripe *old = bkey_s_c_to_stripe(k).v;
+               unsigned i;
+
+               if (old->nr_blocks != new->v.nr_blocks) {
+                       bch_err(c, "error updating stripe: nr_blocks does not match");
+                       ret = -EINVAL;
+                       goto err;
+               }
+
+               for (i = 0; i < new->v.nr_blocks; i++) {
+                       unsigned v = stripe_blockcount_get(old, i);
+
+                       BUG_ON(v &&
+                              (old->ptrs[i].dev != new->v.ptrs[i].dev ||
+                               old->ptrs[i].gen != new->v.ptrs[i].gen ||
+                               old->ptrs[i].offset != new->v.ptrs[i].offset));
+
+                       stripe_blockcount_set(&new->v, i, v);
+               }
+       }
+
+       ret = bch2_trans_update(trans, &iter, &new->k_i, 0);
+err:
+       bch2_trans_iter_exit(trans, &iter);
+       return ret;
+}
+
+static int ec_stripe_update_extent(struct btree_trans *trans,
+                                  struct bpos bucket, u8 gen,
+                                  struct ec_stripe_buf *s,
+                                  struct bpos *bp_pos)
+{
+       struct bch_stripe *v = &bkey_i_to_stripe(&s->key)->v;
+       struct bch_fs *c = trans->c;
+       struct bch_backpointer bp;
+       struct btree_iter iter;
+       struct bkey_s_c k;
+       const struct bch_extent_ptr *ptr_c;
+       struct bch_extent_ptr *ptr, *ec_ptr = NULL;
+       struct bch_extent_stripe_ptr stripe_ptr;
+       struct bkey_i *n;
+       int ret, dev, block;
+
+       ret = bch2_get_next_backpointer(trans, bucket, gen,
+                               bp_pos, &bp, BTREE_ITER_CACHED);
+       if (ret)
+               return ret;
+       if (bpos_eq(*bp_pos, SPOS_MAX))
+               return 0;
+
+       if (bp.level) {
+               struct printbuf buf = PRINTBUF;
+               struct btree_iter node_iter;
+               struct btree *b;
+
+               b = bch2_backpointer_get_node(trans, &node_iter, *bp_pos, bp);
+               bch2_trans_iter_exit(trans, &node_iter);
+
+               if (!b)
+                       return 0;
+
+               prt_printf(&buf, "found btree node in erasure coded bucket: b=%px\n", b);
+               bch2_backpointer_to_text(&buf, &bp);
+
+               bch2_fs_inconsistent(c, "%s", buf.buf);
+               printbuf_exit(&buf);
+               return -EIO;
+       }
+
+       k = bch2_backpointer_get_key(trans, &iter, *bp_pos, bp, BTREE_ITER_INTENT);
+       ret = bkey_err(k);
+       if (ret)
+               return ret;
+       if (!k.k) {
+               /*
+                * extent no longer exists - we could flush the btree
+                * write buffer and retry to verify, but no need:
+                */
+               return 0;
+       }
+
+       if (extent_has_stripe_ptr(k, s->key.k.p.offset))
+               goto out;
+
+       ptr_c = bkey_matches_stripe(v, k, &block);
+       /*
+        * It doesn't generally make sense to erasure code cached ptrs:
+        * XXX: should we be incrementing a counter?
+        */
+       if (!ptr_c || ptr_c->cached)
+               goto out;
+
+       dev = v->ptrs[block].dev;
+
+       n = bch2_trans_kmalloc(trans, bkey_bytes(k.k) + sizeof(stripe_ptr));
+       ret = PTR_ERR_OR_ZERO(n);
+       if (ret)
+               goto out;
+
+       bkey_reassemble(n, k);
+
+       bch2_bkey_drop_ptrs(bkey_i_to_s(n), ptr, ptr->dev != dev);
+       ec_ptr = bch2_bkey_has_device(bkey_i_to_s(n), dev);
+       BUG_ON(!ec_ptr);
+
+       stripe_ptr = (struct bch_extent_stripe_ptr) {
+               .type = 1 << BCH_EXTENT_ENTRY_stripe_ptr,
+               .block          = block,
+               .redundancy     = v->nr_redundant,
+               .idx            = s->key.k.p.offset,
+       };
+
+       __extent_entry_insert(n,
+                       (union bch_extent_entry *) ec_ptr,
+                       (union bch_extent_entry *) &stripe_ptr);
+
+       ret = bch2_trans_update(trans, &iter, n, 0);
+out:
+       bch2_trans_iter_exit(trans, &iter);
+       return ret;
+}
+
+static int ec_stripe_update_bucket(struct btree_trans *trans, struct ec_stripe_buf *s,
+                                  unsigned block)
+{
+       struct bch_fs *c = trans->c;
+       struct bch_stripe *v = &bkey_i_to_stripe(&s->key)->v;
+       struct bch_extent_ptr bucket = v->ptrs[block];
+       struct bpos bucket_pos = PTR_BUCKET_POS(c, &bucket);
+       struct bpos bp_pos = POS_MIN;
+       int ret = 0;
+
+       while (1) {
+               ret = commit_do(trans, NULL, NULL,
+                               BCH_TRANS_COMMIT_no_check_rw|
+                               BCH_TRANS_COMMIT_no_enospc,
+                       ec_stripe_update_extent(trans, bucket_pos, bucket.gen,
+                                               s, &bp_pos));
+               if (ret)
+                       break;
+               if (bkey_eq(bp_pos, POS_MAX))
+                       break;
+
+               bp_pos = bpos_nosnap_successor(bp_pos);
+       }
+
+       return ret;
+}
+
+static int ec_stripe_update_extents(struct bch_fs *c, struct ec_stripe_buf *s)
+{
+       struct btree_trans *trans = bch2_trans_get(c);
+       struct bch_stripe *v = &bkey_i_to_stripe(&s->key)->v;
+       unsigned i, nr_data = v->nr_blocks - v->nr_redundant;
+       int ret = 0;
+
+       ret = bch2_btree_write_buffer_flush_sync(trans);
+       if (ret)
+               goto err;
+
+       for (i = 0; i < nr_data; i++) {
+               ret = ec_stripe_update_bucket(trans, s, i);
+               if (ret)
+                       break;
+       }
+err:
+       bch2_trans_put(trans);
+
+       return ret;
+}
+
+static void zero_out_rest_of_ec_bucket(struct bch_fs *c,
+                                      struct ec_stripe_new *s,
+                                      unsigned block,
+                                      struct open_bucket *ob)
+{
+       struct bch_dev *ca = bch_dev_bkey_exists(c, ob->dev);
+       unsigned offset = ca->mi.bucket_size - ob->sectors_free;
+       int ret;
+
+       if (!bch2_dev_get_ioref(ca, WRITE)) {
+               s->err = -BCH_ERR_erofs_no_writes;
+               return;
+       }
+
+       memset(s->new_stripe.data[block] + (offset << 9),
+              0,
+              ob->sectors_free << 9);
+
+       ret = blkdev_issue_zeroout(ca->disk_sb.bdev,
+                       ob->bucket * ca->mi.bucket_size + offset,
+                       ob->sectors_free,
+                       GFP_KERNEL, 0);
+
+       percpu_ref_put(&ca->io_ref);
+
+       if (ret)
+               s->err = ret;
+}
+
+void bch2_ec_stripe_new_free(struct bch_fs *c, struct ec_stripe_new *s)
+{
+       if (s->idx)
+               bch2_stripe_close(c, s);
+       kfree(s);
+}
+
+/*
+ * data buckets of new stripe all written: create the stripe
+ */
+static void ec_stripe_create(struct ec_stripe_new *s)
+{
+       struct bch_fs *c = s->c;
+       struct open_bucket *ob;
+       struct bch_stripe *v = &bkey_i_to_stripe(&s->new_stripe.key)->v;
+       unsigned i, nr_data = v->nr_blocks - v->nr_redundant;
+       int ret;
+
+       BUG_ON(s->h->s == s);
+
+       closure_sync(&s->iodone);
+
+       if (!s->err) {
+               for (i = 0; i < nr_data; i++)
+                       if (s->blocks[i]) {
+                               ob = c->open_buckets + s->blocks[i];
+
+                               if (ob->sectors_free)
+                                       zero_out_rest_of_ec_bucket(c, s, i, ob);
+                       }
+       }
+
+       if (s->err) {
+               if (!bch2_err_matches(s->err, EROFS))
+                       bch_err(c, "error creating stripe: error writing data buckets");
+               goto err;
+       }
+
+       if (s->have_existing_stripe) {
+               ec_validate_checksums(c, &s->existing_stripe);
+
+               if (ec_do_recov(c, &s->existing_stripe)) {
+                       bch_err(c, "error creating stripe: error reading existing stripe");
+                       goto err;
+               }
+
+               for (i = 0; i < nr_data; i++)
+                       if (stripe_blockcount_get(&bkey_i_to_stripe(&s->existing_stripe.key)->v, i))
+                               swap(s->new_stripe.data[i],
+                                    s->existing_stripe.data[i]);
+
+               ec_stripe_buf_exit(&s->existing_stripe);
+       }
+
+       BUG_ON(!s->allocated);
+       BUG_ON(!s->idx);
+
+       ec_generate_ec(&s->new_stripe);
+
+       ec_generate_checksums(&s->new_stripe);
+
+       /* write p/q: */
+       for (i = nr_data; i < v->nr_blocks; i++)
+               ec_block_io(c, &s->new_stripe, REQ_OP_WRITE, i, &s->iodone);
+       closure_sync(&s->iodone);
+
+       if (ec_nr_failed(&s->new_stripe)) {
+               bch_err(c, "error creating stripe: error writing redundancy buckets");
+               goto err;
+       }
+
+       ret = bch2_trans_do(c, &s->res, NULL,
+                           BCH_TRANS_COMMIT_no_check_rw|
+                           BCH_TRANS_COMMIT_no_enospc,
+                           ec_stripe_key_update(trans,
+                                       bkey_i_to_stripe(&s->new_stripe.key),
+                                       !s->have_existing_stripe));
+       bch_err_msg(c, ret, "creating stripe key");
+       if (ret) {
+               goto err;
+       }
+
+       ret = ec_stripe_update_extents(c, &s->new_stripe);
+       bch_err_msg(c, ret, "error updating extents");
+       if (ret)
+               goto err;
+err:
+       bch2_disk_reservation_put(c, &s->res);
+
+       for (i = 0; i < v->nr_blocks; i++)
+               if (s->blocks[i]) {
+                       ob = c->open_buckets + s->blocks[i];
+
+                       if (i < nr_data) {
+                               ob->ec = NULL;
+                               __bch2_open_bucket_put(c, ob);
+                       } else {
+                               bch2_open_bucket_put(c, ob);
+                       }
+               }
+
+       mutex_lock(&c->ec_stripe_new_lock);
+       list_del(&s->list);
+       mutex_unlock(&c->ec_stripe_new_lock);
+       wake_up(&c->ec_stripe_new_wait);
+
+       ec_stripe_buf_exit(&s->existing_stripe);
+       ec_stripe_buf_exit(&s->new_stripe);
+       closure_debug_destroy(&s->iodone);
+
+       ec_stripe_new_put(c, s, STRIPE_REF_stripe);
+}
+
+static struct ec_stripe_new *get_pending_stripe(struct bch_fs *c)
+{
+       struct ec_stripe_new *s;
+
+       mutex_lock(&c->ec_stripe_new_lock);
+       list_for_each_entry(s, &c->ec_stripe_new_list, list)
+               if (!atomic_read(&s->ref[STRIPE_REF_io]))
+                       goto out;
+       s = NULL;
+out:
+       mutex_unlock(&c->ec_stripe_new_lock);
+
+       return s;
+}
+
+static void ec_stripe_create_work(struct work_struct *work)
+{
+       struct bch_fs *c = container_of(work,
+               struct bch_fs, ec_stripe_create_work);
+       struct ec_stripe_new *s;
+
+       while ((s = get_pending_stripe(c)))
+               ec_stripe_create(s);
+
+       bch2_write_ref_put(c, BCH_WRITE_REF_stripe_create);
+}
+
+void bch2_ec_do_stripe_creates(struct bch_fs *c)
+{
+       bch2_write_ref_get(c, BCH_WRITE_REF_stripe_create);
+
+       if (!queue_work(system_long_wq, &c->ec_stripe_create_work))
+               bch2_write_ref_put(c, BCH_WRITE_REF_stripe_create);
+}
+
+static void ec_stripe_set_pending(struct bch_fs *c, struct ec_stripe_head *h)
+{
+       struct ec_stripe_new *s = h->s;
+
+       BUG_ON(!s->allocated && !s->err);
+
+       h->s            = NULL;
+       s->pending      = true;
+
+       mutex_lock(&c->ec_stripe_new_lock);
+       list_add(&s->list, &c->ec_stripe_new_list);
+       mutex_unlock(&c->ec_stripe_new_lock);
+
+       ec_stripe_new_put(c, s, STRIPE_REF_io);
+}
+
+void bch2_ec_bucket_cancel(struct bch_fs *c, struct open_bucket *ob)
+{
+       struct ec_stripe_new *s = ob->ec;
+
+       s->err = -EIO;
+}
+
+void *bch2_writepoint_ec_buf(struct bch_fs *c, struct write_point *wp)
+{
+       struct open_bucket *ob = ec_open_bucket(c, &wp->ptrs);
+       struct bch_dev *ca;
+       unsigned offset;
+
+       if (!ob)
+               return NULL;
+
+       BUG_ON(!ob->ec->new_stripe.data[ob->ec_idx]);
+
+       ca      = bch_dev_bkey_exists(c, ob->dev);
+       offset  = ca->mi.bucket_size - ob->sectors_free;
+
+       return ob->ec->new_stripe.data[ob->ec_idx] + (offset << 9);
+}
+
+static int unsigned_cmp(const void *_l, const void *_r)
+{
+       unsigned l = *((const unsigned *) _l);
+       unsigned r = *((const unsigned *) _r);
+
+       return cmp_int(l, r);
+}
+
+/* pick most common bucket size: */
+static unsigned pick_blocksize(struct bch_fs *c,
+                              struct bch_devs_mask *devs)
+{
+       unsigned nr = 0, sizes[BCH_SB_MEMBERS_MAX];
+       struct {
+               unsigned nr, size;
+       } cur = { 0, 0 }, best = { 0, 0 };
+
+       for_each_member_device_rcu(c, ca, devs)
+               sizes[nr++] = ca->mi.bucket_size;
+
+       sort(sizes, nr, sizeof(unsigned), unsigned_cmp, NULL);
+
+       for (unsigned i = 0; i < nr; i++) {
+               if (sizes[i] != cur.size) {
+                       if (cur.nr > best.nr)
+                               best = cur;
+
+                       cur.nr = 0;
+                       cur.size = sizes[i];
+               }
+
+               cur.nr++;
+       }
+
+       if (cur.nr > best.nr)
+               best = cur;
+
+       return best.size;
+}
+
+static bool may_create_new_stripe(struct bch_fs *c)
+{
+       return false;
+}
+
+static void ec_stripe_key_init(struct bch_fs *c,
+                              struct bkey_i *k,
+                              unsigned nr_data,
+                              unsigned nr_parity,
+                              unsigned stripe_size)
+{
+       struct bkey_i_stripe *s = bkey_stripe_init(k);
+       unsigned u64s;
+
+       s->v.sectors                    = cpu_to_le16(stripe_size);
+       s->v.algorithm                  = 0;
+       s->v.nr_blocks                  = nr_data + nr_parity;
+       s->v.nr_redundant               = nr_parity;
+       s->v.csum_granularity_bits      = ilog2(c->opts.encoded_extent_max >> 9);
+       s->v.csum_type                  = BCH_CSUM_crc32c;
+       s->v.pad                        = 0;
+
+       while ((u64s = stripe_val_u64s(&s->v)) > BKEY_VAL_U64s_MAX) {
+               BUG_ON(1 << s->v.csum_granularity_bits >=
+                      le16_to_cpu(s->v.sectors) ||
+                      s->v.csum_granularity_bits == U8_MAX);
+               s->v.csum_granularity_bits++;
+       }
+
+       set_bkey_val_u64s(&s->k, u64s);
+}
+
+static int ec_new_stripe_alloc(struct bch_fs *c, struct ec_stripe_head *h)
+{
+       struct ec_stripe_new *s;
+
+       lockdep_assert_held(&h->lock);
+
+       s = kzalloc(sizeof(*s), GFP_KERNEL);
+       if (!s)
+               return -BCH_ERR_ENOMEM_ec_new_stripe_alloc;
+
+       mutex_init(&s->lock);
+       closure_init(&s->iodone, NULL);
+       atomic_set(&s->ref[STRIPE_REF_stripe], 1);
+       atomic_set(&s->ref[STRIPE_REF_io], 1);
+       s->c            = c;
+       s->h            = h;
+       s->nr_data      = min_t(unsigned, h->nr_active_devs,
+                               BCH_BKEY_PTRS_MAX) - h->redundancy;
+       s->nr_parity    = h->redundancy;
+
+       ec_stripe_key_init(c, &s->new_stripe.key,
+                          s->nr_data, s->nr_parity, h->blocksize);
+
+       h->s = s;
+       return 0;
+}
+
+static struct ec_stripe_head *
+ec_new_stripe_head_alloc(struct bch_fs *c, unsigned target,
+                        unsigned algo, unsigned redundancy,
+                        enum bch_watermark watermark)
+{
+       struct ec_stripe_head *h;
+
+       h = kzalloc(sizeof(*h), GFP_KERNEL);
+       if (!h)
+               return NULL;
+
+       mutex_init(&h->lock);
+       BUG_ON(!mutex_trylock(&h->lock));
+
+       h->target       = target;
+       h->algo         = algo;
+       h->redundancy   = redundancy;
+       h->watermark    = watermark;
+
+       rcu_read_lock();
+       h->devs = target_rw_devs(c, BCH_DATA_user, target);
+
+       for_each_member_device_rcu(c, ca, &h->devs)
+               if (!ca->mi.durability)
+                       __clear_bit(ca->dev_idx, h->devs.d);
+
+       h->blocksize = pick_blocksize(c, &h->devs);
+
+       for_each_member_device_rcu(c, ca, &h->devs)
+               if (ca->mi.bucket_size == h->blocksize)
+                       h->nr_active_devs++;
+
+       rcu_read_unlock();
+
+       /*
+        * If we only have redundancy + 1 devices, we're better off with just
+        * replication:
+        */
+       if (h->nr_active_devs < h->redundancy + 2)
+               bch_err(c, "insufficient devices available to create stripe (have %u, need %u) - mismatched bucket sizes?",
+                       h->nr_active_devs, h->redundancy + 2);
+
+       list_add(&h->list, &c->ec_stripe_head_list);
+       return h;
+}
+
+void bch2_ec_stripe_head_put(struct bch_fs *c, struct ec_stripe_head *h)
+{
+       if (h->s &&
+           h->s->allocated &&
+           bitmap_weight(h->s->blocks_allocated,
+                         h->s->nr_data) == h->s->nr_data)
+               ec_stripe_set_pending(c, h);
+
+       mutex_unlock(&h->lock);
+}
+
+static struct ec_stripe_head *
+__bch2_ec_stripe_head_get(struct btree_trans *trans,
+                         unsigned target,
+                         unsigned algo,
+                         unsigned redundancy,
+                         enum bch_watermark watermark)
+{
+       struct bch_fs *c = trans->c;
+       struct ec_stripe_head *h;
+       int ret;
+
+       if (!redundancy)
+               return NULL;
+
+       ret = bch2_trans_mutex_lock(trans, &c->ec_stripe_head_lock);
+       if (ret)
+               return ERR_PTR(ret);
+
+       if (test_bit(BCH_FS_going_ro, &c->flags)) {
+               h = ERR_PTR(-BCH_ERR_erofs_no_writes);
+               goto found;
+       }
+
+       list_for_each_entry(h, &c->ec_stripe_head_list, list)
+               if (h->target           == target &&
+                   h->algo             == algo &&
+                   h->redundancy       == redundancy &&
+                   h->watermark        == watermark) {
+                       ret = bch2_trans_mutex_lock(trans, &h->lock);
+                       if (ret)
+                               h = ERR_PTR(ret);
+                       goto found;
+               }
+
+       h = ec_new_stripe_head_alloc(c, target, algo, redundancy, watermark);
+found:
+       if (!IS_ERR_OR_NULL(h) &&
+           h->nr_active_devs < h->redundancy + 2) {
+               mutex_unlock(&h->lock);
+               h = NULL;
+       }
+       mutex_unlock(&c->ec_stripe_head_lock);
+       return h;
+}
+
+static int new_stripe_alloc_buckets(struct btree_trans *trans, struct ec_stripe_head *h,
+                                   enum bch_watermark watermark, struct closure *cl)
+{
+       struct bch_fs *c = trans->c;
+       struct bch_devs_mask devs = h->devs;
+       struct open_bucket *ob;
+       struct open_buckets buckets;
+       struct bch_stripe *v = &bkey_i_to_stripe(&h->s->new_stripe.key)->v;
+       unsigned i, j, nr_have_parity = 0, nr_have_data = 0;
+       bool have_cache = true;
+       int ret = 0;
+
+       BUG_ON(v->nr_blocks     != h->s->nr_data + h->s->nr_parity);
+       BUG_ON(v->nr_redundant  != h->s->nr_parity);
+
+       for_each_set_bit(i, h->s->blocks_gotten, v->nr_blocks) {
+               __clear_bit(v->ptrs[i].dev, devs.d);
+               if (i < h->s->nr_data)
+                       nr_have_data++;
+               else
+                       nr_have_parity++;
+       }
+
+       BUG_ON(nr_have_data     > h->s->nr_data);
+       BUG_ON(nr_have_parity   > h->s->nr_parity);
+
+       buckets.nr = 0;
+       if (nr_have_parity < h->s->nr_parity) {
+               ret = bch2_bucket_alloc_set_trans(trans, &buckets,
+                                           &h->parity_stripe,
+                                           &devs,
+                                           h->s->nr_parity,
+                                           &nr_have_parity,
+                                           &have_cache, 0,
+                                           BCH_DATA_parity,
+                                           watermark,
+                                           cl);
+
+               open_bucket_for_each(c, &buckets, ob, i) {
+                       j = find_next_zero_bit(h->s->blocks_gotten,
+                                              h->s->nr_data + h->s->nr_parity,
+                                              h->s->nr_data);
+                       BUG_ON(j >= h->s->nr_data + h->s->nr_parity);
+
+                       h->s->blocks[j] = buckets.v[i];
+                       v->ptrs[j] = bch2_ob_ptr(c, ob);
+                       __set_bit(j, h->s->blocks_gotten);
+               }
+
+               if (ret)
+                       return ret;
+       }
+
+       buckets.nr = 0;
+       if (nr_have_data < h->s->nr_data) {
+               ret = bch2_bucket_alloc_set_trans(trans, &buckets,
+                                           &h->block_stripe,
+                                           &devs,
+                                           h->s->nr_data,
+                                           &nr_have_data,
+                                           &have_cache, 0,
+                                           BCH_DATA_user,
+                                           watermark,
+                                           cl);
+
+               open_bucket_for_each(c, &buckets, ob, i) {
+                       j = find_next_zero_bit(h->s->blocks_gotten,
+                                              h->s->nr_data, 0);
+                       BUG_ON(j >= h->s->nr_data);
+
+                       h->s->blocks[j] = buckets.v[i];
+                       v->ptrs[j] = bch2_ob_ptr(c, ob);
+                       __set_bit(j, h->s->blocks_gotten);
+               }
+
+               if (ret)
+                       return ret;
+       }
+
+       return 0;
+}
+
+/* XXX: doesn't obey target: */
+static s64 get_existing_stripe(struct bch_fs *c,
+                              struct ec_stripe_head *head)
+{
+       ec_stripes_heap *h = &c->ec_stripes_heap;
+       struct stripe *m;
+       size_t heap_idx;
+       u64 stripe_idx;
+       s64 ret = -1;
+
+       if (may_create_new_stripe(c))
+               return -1;
+
+       mutex_lock(&c->ec_stripes_heap_lock);
+       for (heap_idx = 0; heap_idx < h->used; heap_idx++) {
+               /* No blocks worth reusing, stripe will just be deleted: */
+               if (!h->data[heap_idx].blocks_nonempty)
+                       continue;
+
+               stripe_idx = h->data[heap_idx].idx;
+
+               m = genradix_ptr(&c->stripes, stripe_idx);
+
+               if (m->algorithm        == head->algo &&
+                   m->nr_redundant     == head->redundancy &&
+                   m->sectors          == head->blocksize &&
+                   m->blocks_nonempty  < m->nr_blocks - m->nr_redundant &&
+                   bch2_try_open_stripe(c, head->s, stripe_idx)) {
+                       ret = stripe_idx;
+                       break;
+               }
+       }
+       mutex_unlock(&c->ec_stripes_heap_lock);
+       return ret;
+}
+
+static int __bch2_ec_stripe_head_reuse(struct btree_trans *trans, struct ec_stripe_head *h)
+{
+       struct bch_fs *c = trans->c;
+       struct bch_stripe *new_v = &bkey_i_to_stripe(&h->s->new_stripe.key)->v;
+       struct bch_stripe *existing_v;
+       unsigned i;
+       s64 idx;
+       int ret;
+
+       /*
+        * If we can't allocate a new stripe, and there's no stripes with empty
+        * blocks for us to reuse, that means we have to wait on copygc:
+        */
+       idx = get_existing_stripe(c, h);
+       if (idx < 0)
+               return -BCH_ERR_stripe_alloc_blocked;
+
+       ret = get_stripe_key_trans(trans, idx, &h->s->existing_stripe);
+       if (ret) {
+               bch2_stripe_close(c, h->s);
+               if (!bch2_err_matches(ret, BCH_ERR_transaction_restart))
+                       bch2_fs_fatal_error(c, "error reading stripe key: %s", bch2_err_str(ret));
+               return ret;
+       }
+
+       existing_v = &bkey_i_to_stripe(&h->s->existing_stripe.key)->v;
+
+       BUG_ON(existing_v->nr_redundant != h->s->nr_parity);
+       h->s->nr_data = existing_v->nr_blocks -
+               existing_v->nr_redundant;
+
+       ret = ec_stripe_buf_init(&h->s->existing_stripe, 0, h->blocksize);
+       if (ret) {
+               bch2_stripe_close(c, h->s);
+               return ret;
+       }
+
+       BUG_ON(h->s->existing_stripe.size != h->blocksize);
+       BUG_ON(h->s->existing_stripe.size != le16_to_cpu(existing_v->sectors));
+
+       /*
+        * Free buckets we initially allocated - they might conflict with
+        * blocks from the stripe we're reusing:
+        */
+       for_each_set_bit(i, h->s->blocks_gotten, new_v->nr_blocks) {
+               bch2_open_bucket_put(c, c->open_buckets + h->s->blocks[i]);
+               h->s->blocks[i] = 0;
+       }
+       memset(h->s->blocks_gotten, 0, sizeof(h->s->blocks_gotten));
+       memset(h->s->blocks_allocated, 0, sizeof(h->s->blocks_allocated));
+
+       for (i = 0; i < existing_v->nr_blocks; i++) {
+               if (stripe_blockcount_get(existing_v, i)) {
+                       __set_bit(i, h->s->blocks_gotten);
+                       __set_bit(i, h->s->blocks_allocated);
+               }
+
+               ec_block_io(c, &h->s->existing_stripe, READ, i, &h->s->iodone);
+       }
+
+       bkey_copy(&h->s->new_stripe.key, &h->s->existing_stripe.key);
+       h->s->have_existing_stripe = true;
+
+       return 0;
+}
+
+static int __bch2_ec_stripe_head_reserve(struct btree_trans *trans, struct ec_stripe_head *h)
+{
+       struct bch_fs *c = trans->c;
+       struct btree_iter iter;
+       struct bkey_s_c k;
+       struct bpos min_pos = POS(0, 1);
+       struct bpos start_pos = bpos_max(min_pos, POS(0, c->ec_stripe_hint));
+       int ret;
+
+       if (!h->s->res.sectors) {
+               ret = bch2_disk_reservation_get(c, &h->s->res,
+                                       h->blocksize,
+                                       h->s->nr_parity,
+                                       BCH_DISK_RESERVATION_NOFAIL);
+               if (ret)
+                       return ret;
+       }
+
+       for_each_btree_key_norestart(trans, iter, BTREE_ID_stripes, start_pos,
+                          BTREE_ITER_SLOTS|BTREE_ITER_INTENT, k, ret) {
+               if (bkey_gt(k.k->p, POS(0, U32_MAX))) {
+                       if (start_pos.offset) {
+                               start_pos = min_pos;
+                               bch2_btree_iter_set_pos(&iter, start_pos);
+                               continue;
+                       }
+
+                       ret = -BCH_ERR_ENOSPC_stripe_create;
+                       break;
+               }
+
+               if (bkey_deleted(k.k) &&
+                   bch2_try_open_stripe(c, h->s, k.k->p.offset))
+                       break;
+       }
+
+       c->ec_stripe_hint = iter.pos.offset;
+
+       if (ret)
+               goto err;
+
+       ret = ec_stripe_mem_alloc(trans, &iter);
+       if (ret) {
+               bch2_stripe_close(c, h->s);
+               goto err;
+       }
+
+       h->s->new_stripe.key.k.p = iter.pos;
+out:
+       bch2_trans_iter_exit(trans, &iter);
+       return ret;
+err:
+       bch2_disk_reservation_put(c, &h->s->res);
+       goto out;
+}
+
+struct ec_stripe_head *bch2_ec_stripe_head_get(struct btree_trans *trans,
+                                              unsigned target,
+                                              unsigned algo,
+                                              unsigned redundancy,
+                                              enum bch_watermark watermark,
+                                              struct closure *cl)
+{
+       struct bch_fs *c = trans->c;
+       struct ec_stripe_head *h;
+       bool waiting = false;
+       int ret;
+
+       h = __bch2_ec_stripe_head_get(trans, target, algo, redundancy, watermark);
+       if (IS_ERR_OR_NULL(h))
+               return h;
+
+       if (!h->s) {
+               ret = ec_new_stripe_alloc(c, h);
+               if (ret) {
+                       bch_err(c, "failed to allocate new stripe");
+                       goto err;
+               }
+       }
+
+       if (h->s->allocated)
+               goto allocated;
+
+       if (h->s->have_existing_stripe)
+               goto alloc_existing;
+
+       /* First, try to allocate a full stripe: */
+       ret =   new_stripe_alloc_buckets(trans, h, BCH_WATERMARK_stripe, NULL) ?:
+               __bch2_ec_stripe_head_reserve(trans, h);
+       if (!ret)
+               goto allocate_buf;
+       if (bch2_err_matches(ret, BCH_ERR_transaction_restart) ||
+           bch2_err_matches(ret, ENOMEM))
+               goto err;
+
+       /*
+        * Not enough buckets available for a full stripe: we must reuse an
+        * existing stripe:
+        */
+       while (1) {
+               ret = __bch2_ec_stripe_head_reuse(trans, h);
+               if (!ret)
+                       break;
+               if (waiting || !cl || ret != -BCH_ERR_stripe_alloc_blocked)
+                       goto err;
+
+               if (watermark == BCH_WATERMARK_copygc) {
+                       ret =   new_stripe_alloc_buckets(trans, h, watermark, NULL) ?:
+                               __bch2_ec_stripe_head_reserve(trans, h);
+                       if (ret)
+                               goto err;
+                       goto allocate_buf;
+               }
+
+               /* XXX freelist_wait? */
+               closure_wait(&c->freelist_wait, cl);
+               waiting = true;
+       }
+
+       if (waiting)
+               closure_wake_up(&c->freelist_wait);
+alloc_existing:
+       /*
+        * Retry allocating buckets, with the watermark for this
+        * particular write:
+        */
+       ret = new_stripe_alloc_buckets(trans, h, watermark, cl);
+       if (ret)
+               goto err;
+
+allocate_buf:
+       ret = ec_stripe_buf_init(&h->s->new_stripe, 0, h->blocksize);
+       if (ret)
+               goto err;
+
+       h->s->allocated = true;
+allocated:
+       BUG_ON(!h->s->idx);
+       BUG_ON(!h->s->new_stripe.data[0]);
+       BUG_ON(trans->restarted);
+       return h;
+err:
+       bch2_ec_stripe_head_put(c, h);
+       return ERR_PTR(ret);
+}
+
+static void __bch2_ec_stop(struct bch_fs *c, struct bch_dev *ca)
+{
+       struct ec_stripe_head *h;
+       struct open_bucket *ob;
+       unsigned i;
+
+       mutex_lock(&c->ec_stripe_head_lock);
+       list_for_each_entry(h, &c->ec_stripe_head_list, list) {
+               mutex_lock(&h->lock);
+               if (!h->s)
+                       goto unlock;
+
+               if (!ca)
+                       goto found;
+
+               for (i = 0; i < bkey_i_to_stripe(&h->s->new_stripe.key)->v.nr_blocks; i++) {
+                       if (!h->s->blocks[i])
+                               continue;
+
+                       ob = c->open_buckets + h->s->blocks[i];
+                       if (ob->dev == ca->dev_idx)
+                               goto found;
+               }
+               goto unlock;
+found:
+               h->s->err = -BCH_ERR_erofs_no_writes;
+               ec_stripe_set_pending(c, h);
+unlock:
+               mutex_unlock(&h->lock);
+       }
+       mutex_unlock(&c->ec_stripe_head_lock);
+}
+
+void bch2_ec_stop_dev(struct bch_fs *c, struct bch_dev *ca)
+{
+       __bch2_ec_stop(c, ca);
+}
+
+void bch2_fs_ec_stop(struct bch_fs *c)
+{
+       __bch2_ec_stop(c, NULL);
+}
+
+static bool bch2_fs_ec_flush_done(struct bch_fs *c)
+{
+       bool ret;
+
+       mutex_lock(&c->ec_stripe_new_lock);
+       ret = list_empty(&c->ec_stripe_new_list);
+       mutex_unlock(&c->ec_stripe_new_lock);
+
+       return ret;
+}
+
+void bch2_fs_ec_flush(struct bch_fs *c)
+{
+       wait_event(c->ec_stripe_new_wait, bch2_fs_ec_flush_done(c));
+}
+
+int bch2_stripes_read(struct bch_fs *c)
+{
+       int ret = bch2_trans_run(c,
+               for_each_btree_key(trans, iter, BTREE_ID_stripes, POS_MIN,
+                                  BTREE_ITER_PREFETCH, k, ({
+                       if (k.k->type != KEY_TYPE_stripe)
+                               continue;
+
+                       ret = __ec_stripe_mem_alloc(c, k.k->p.offset, GFP_KERNEL);
+                       if (ret)
+                               break;
+
+                       const struct bch_stripe *s = bkey_s_c_to_stripe(k).v;
+
+                       struct stripe *m = genradix_ptr(&c->stripes, k.k->p.offset);
+                       m->sectors      = le16_to_cpu(s->sectors);
+                       m->algorithm    = s->algorithm;
+                       m->nr_blocks    = s->nr_blocks;
+                       m->nr_redundant = s->nr_redundant;
+                       m->blocks_nonempty = 0;
+
+                       for (unsigned i = 0; i < s->nr_blocks; i++)
+                               m->blocks_nonempty += !!stripe_blockcount_get(s, i);
+
+                       bch2_stripes_heap_insert(c, m, k.k->p.offset);
+                       0;
+               })));
+       bch_err_fn(c, ret);
+       return ret;
+}
+
+void bch2_stripes_heap_to_text(struct printbuf *out, struct bch_fs *c)
+{
+       ec_stripes_heap *h = &c->ec_stripes_heap;
+       struct stripe *m;
+       size_t i;
+
+       mutex_lock(&c->ec_stripes_heap_lock);
+       for (i = 0; i < min_t(size_t, h->used, 50); i++) {
+               m = genradix_ptr(&c->stripes, h->data[i].idx);
+
+               prt_printf(out, "%zu %u/%u+%u", h->data[i].idx,
+                      h->data[i].blocks_nonempty,
+                      m->nr_blocks - m->nr_redundant,
+                      m->nr_redundant);
+               if (bch2_stripe_is_open(c, h->data[i].idx))
+                       prt_str(out, " open");
+               prt_newline(out);
+       }
+       mutex_unlock(&c->ec_stripes_heap_lock);
+}
+
+void bch2_new_stripes_to_text(struct printbuf *out, struct bch_fs *c)
+{
+       struct ec_stripe_head *h;
+       struct ec_stripe_new *s;
+
+       mutex_lock(&c->ec_stripe_head_lock);
+       list_for_each_entry(h, &c->ec_stripe_head_list, list) {
+               prt_printf(out, "target %u algo %u redundancy %u %s:\n",
+                      h->target, h->algo, h->redundancy,
+                      bch2_watermarks[h->watermark]);
+
+               if (h->s)
+                       prt_printf(out, "\tidx %llu blocks %u+%u allocated %u\n",
+                              h->s->idx, h->s->nr_data, h->s->nr_parity,
+                              bitmap_weight(h->s->blocks_allocated,
+                                            h->s->nr_data));
+       }
+       mutex_unlock(&c->ec_stripe_head_lock);
+
+       prt_printf(out, "in flight:\n");
+
+       mutex_lock(&c->ec_stripe_new_lock);
+       list_for_each_entry(s, &c->ec_stripe_new_list, list) {
+               prt_printf(out, "\tidx %llu blocks %u+%u ref %u %u %s\n",
+                          s->idx, s->nr_data, s->nr_parity,
+                          atomic_read(&s->ref[STRIPE_REF_io]),
+                          atomic_read(&s->ref[STRIPE_REF_stripe]),
+                          bch2_watermarks[s->h->watermark]);
+       }
+       mutex_unlock(&c->ec_stripe_new_lock);
+}
+
+void bch2_fs_ec_exit(struct bch_fs *c)
+{
+       struct ec_stripe_head *h;
+       unsigned i;
+
+       while (1) {
+               mutex_lock(&c->ec_stripe_head_lock);
+               h = list_first_entry_or_null(&c->ec_stripe_head_list,
+                                            struct ec_stripe_head, list);
+               if (h)
+                       list_del(&h->list);
+               mutex_unlock(&c->ec_stripe_head_lock);
+               if (!h)
+                       break;
+
+               if (h->s) {
+                       for (i = 0; i < bkey_i_to_stripe(&h->s->new_stripe.key)->v.nr_blocks; i++)
+                               BUG_ON(h->s->blocks[i]);
+
+                       kfree(h->s);
+               }
+               kfree(h);
+       }
+
+       BUG_ON(!list_empty(&c->ec_stripe_new_list));
+
+       free_heap(&c->ec_stripes_heap);
+       genradix_free(&c->stripes);
+       bioset_exit(&c->ec_bioset);
+}
+
+void bch2_fs_ec_init_early(struct bch_fs *c)
+{
+       spin_lock_init(&c->ec_stripes_new_lock);
+       mutex_init(&c->ec_stripes_heap_lock);
+
+       INIT_LIST_HEAD(&c->ec_stripe_head_list);
+       mutex_init(&c->ec_stripe_head_lock);
+
+       INIT_LIST_HEAD(&c->ec_stripe_new_list);
+       mutex_init(&c->ec_stripe_new_lock);
+       init_waitqueue_head(&c->ec_stripe_new_wait);
+
+       INIT_WORK(&c->ec_stripe_create_work, ec_stripe_create_work);
+       INIT_WORK(&c->ec_stripe_delete_work, ec_stripe_delete_work);
+}
+
+int bch2_fs_ec_init(struct bch_fs *c)
+{
+       return bioset_init(&c->ec_bioset, 1, offsetof(struct ec_bio, bio),
+                          BIOSET_NEED_BVECS);
+}