From a2cb8a6236daafbea5e3d9d720f5e55ba692817b Mon Sep 17 00:00:00 2001
From: Kent Overstreet <kent.overstreet@linux.dev>
Date: Fri, 28 Jun 2024 13:28:30 -0400
Subject: [PATCH] bcachefs: Self healing on read IO error
This repurposes the promote path, which already knows how to call
data_update() after a read: we now automatically rewrite bad data when
we get a read error and then successfully retry from a different
replica.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
---
fs/bcachefs/extents.c | 8 ++---
fs/bcachefs/extents.h | 2 ++
fs/bcachefs/io_read.c | 69 +++++++++++++++++++++++++++++--------------
3 files changed, 53 insertions(+), 26 deletions(-)
diff --git a/fs/bcachefs/extents.c b/fs/bcachefs/extents.c
index 057df38fccf8c..07973198e35fb 100644
--- a/fs/bcachefs/extents.c
+++ b/fs/bcachefs/extents.c
@@ -37,8 +37,8 @@ static void bch2_extent_crc_pack(union bch_extent_crc *,
struct bch_extent_crc_unpacked,
enum bch_extent_entry_type);
-static struct bch_dev_io_failures *dev_io_failures(struct bch_io_failures *f,
- unsigned dev)
+struct bch_dev_io_failures *bch2_dev_io_failures(struct bch_io_failures *f,
+ unsigned dev)
{
struct bch_dev_io_failures *i;
@@ -52,7 +52,7 @@ static struct bch_dev_io_failures *dev_io_failures(struct bch_io_failures *f,
void bch2_mark_io_failure(struct bch_io_failures *failed,
struct extent_ptr_decoded *p)
{
- struct bch_dev_io_failures *f = dev_io_failures(failed, p->ptr.dev);
+ struct bch_dev_io_failures *f = bch2_dev_io_failures(failed, p->ptr.dev);
if (!f) {
BUG_ON(failed->nr >= ARRAY_SIZE(failed->devs));
@@ -140,7 +140,7 @@ int bch2_bkey_pick_read_device(struct bch_fs *c, struct bkey_s_c k,
if (p.ptr.cached && (!ca || dev_ptr_stale_rcu(ca, &p.ptr)))
continue;
- f = failed ? dev_io_failures(failed, p.ptr.dev) : NULL;
+ f = failed ? bch2_dev_io_failures(failed, p.ptr.dev) : NULL;
if (f)
p.idx = f->nr_failed < f->nr_retries
? f->idx
diff --git a/fs/bcachefs/extents.h b/fs/bcachefs/extents.h
index 530686aa6fd98..facdb8a86eec8 100644
--- a/fs/bcachefs/extents.h
+++ b/fs/bcachefs/extents.h
@@ -399,6 +399,8 @@ out: \
/* utility code common to all keys with pointers: */
+struct bch_dev_io_failures *bch2_dev_io_failures(struct bch_io_failures *,
+ unsigned);
void bch2_mark_io_failure(struct bch_io_failures *,
struct extent_ptr_decoded *);
int bch2_bkey_pick_read_device(struct bch_fs *, struct bkey_s_c,
diff --git a/fs/bcachefs/io_read.c b/fs/bcachefs/io_read.c
index ebf39ef72fb2c..8b484c75757c1 100644
--- a/fs/bcachefs/io_read.c
+++ b/fs/bcachefs/io_read.c
@@ -93,21 +93,24 @@ static const struct rhashtable_params bch_promote_params = {
static inline int should_promote(struct bch_fs *c, struct bkey_s_c k,
struct bpos pos,
struct bch_io_opts opts,
- unsigned flags)
+ unsigned flags,
+ struct bch_io_failures *failed)
{
- BUG_ON(!opts.promote_target);
+ if (!failed) {
+ BUG_ON(!opts.promote_target);
- if (!(flags & BCH_READ_MAY_PROMOTE))
- return -BCH_ERR_nopromote_may_not;
+ if (!(flags & BCH_READ_MAY_PROMOTE))
+ return -BCH_ERR_nopromote_may_not;
- if (bch2_bkey_has_target(c, k, opts.promote_target))
- return -BCH_ERR_nopromote_already_promoted;
+ if (bch2_bkey_has_target(c, k, opts.promote_target))
+ return -BCH_ERR_nopromote_already_promoted;
- if (bkey_extent_is_unwritten(k))
- return -BCH_ERR_nopromote_unwritten;
+ if (bkey_extent_is_unwritten(k))
+ return -BCH_ERR_nopromote_unwritten;
- if (bch2_target_congested(c, opts.promote_target))
- return -BCH_ERR_nopromote_congested;
+ if (bch2_target_congested(c, opts.promote_target))
+ return -BCH_ERR_nopromote_congested;
+ }
if (rhashtable_lookup_fast(&c->promote_table, &pos,
bch_promote_params))
@@ -164,7 +167,8 @@ static struct promote_op *__promote_alloc(struct btree_trans *trans,
struct extent_ptr_decoded *pick,
struct bch_io_opts opts,
unsigned sectors,
- struct bch_read_bio **rbio)
+ struct bch_read_bio **rbio,
+ struct bch_io_failures *failed)
{
struct bch_fs *c = trans->c;
struct promote_op *op = NULL;
@@ -217,14 +221,28 @@ static struct promote_op *__promote_alloc(struct btree_trans *trans,
bio = &op->write.op.wbio.bio;
bio_init(bio, NULL, bio->bi_inline_vecs, pages, 0);
+ struct data_update_opts update_opts = {};
+
+ if (!failed) {
+ update_opts.target = opts.promote_target;
+ update_opts.extra_replicas = 1;
+ update_opts.write_flags = BCH_WRITE_ALLOC_NOWAIT|BCH_WRITE_CACHED;
+ } else {
+ update_opts.target = opts.foreground_target;
+
+ struct bkey_ptrs_c ptrs = bch2_bkey_ptrs_c(k);
+ unsigned i = 0;
+ bkey_for_each_ptr(ptrs, ptr) {
+ if (bch2_dev_io_failures(failed, ptr->dev))
+ update_opts.rewrite_ptrs |= BIT(i);
+ i++;
+ }
+ }
+
ret = bch2_data_update_init(trans, NULL, NULL, &op->write,
writepoint_hashed((unsigned long) current),
opts,
- (struct data_update_opts) {
- .target = opts.promote_target,
- .extra_replicas = 1,
- .write_flags = BCH_WRITE_ALLOC_NOWAIT|BCH_WRITE_CACHED,
- },
+ update_opts,
btree_id, k);
/*
* possible errors: -BCH_ERR_nocow_lock_blocked,
@@ -258,10 +276,17 @@ static struct promote_op *promote_alloc(struct btree_trans *trans,
unsigned flags,
struct bch_read_bio **rbio,
bool *bounce,
- bool *read_full)
+ bool *read_full,
+ struct bch_io_failures *failed)
{
struct bch_fs *c = trans->c;
- bool promote_full = *read_full || READ_ONCE(c->promote_whole_extents);
+ /*
+ * if failed != NULL we're not actually doing a promote, we're
+ * recovering from an io/checksum error
+ */
+ bool promote_full = (failed ||
+ *read_full ||
+ READ_ONCE(c->promote_whole_extents));
/* data might have to be decompressed in the write path: */
unsigned sectors = promote_full
? max(pick->crc.compressed_size, pick->crc.live_size)
@@ -272,7 +297,7 @@ static struct promote_op *promote_alloc(struct btree_trans *trans,
struct promote_op *promote;
int ret;
- ret = should_promote(c, k, pos, opts, flags);
+ ret = should_promote(c, k, pos, opts, flags, failed);
if (ret)
goto nopromote;
@@ -280,7 +305,7 @@ static struct promote_op *promote_alloc(struct btree_trans *trans,
k.k->type == KEY_TYPE_reflink_v
? BTREE_ID_reflink
: BTREE_ID_extents,
- k, pos, pick, opts, sectors, rbio);
+ k, pos, pick, opts, sectors, rbio, failed);
ret = PTR_ERR_OR_ZERO(promote);
if (ret)
goto nopromote;
@@ -910,9 +935,9 @@ int __bch2_read_extent(struct btree_trans *trans, struct bch_read_bio *orig,
bounce = true;
}
- if (orig->opts.promote_target)
+ if (orig->opts.promote_target)// || failed)
promote = promote_alloc(trans, iter, k, &pick, orig->opts, flags,
- &rbio, &bounce, &read_full);
+ &rbio, &bounce, &read_full, failed);
if (!read_full) {
EBUG_ON(crc_is_compressed(pick.crc));
--
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