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bcachefs: don't block reads if we're promoting 

The promote path calls data_update_init() and now that we take locks here,
there's potential for promote to block our read path, just error
when we can't take the lock instead of blocking.

Signed-off-by: Daniel Hill <daniel@gluo.nz>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Daniel Hill 2023-01-06 21:11:07 +13:00 committed by Kent Overstreet
parent 0093b9e970
commit 3482dd6a25
3 changed files with 25 additions and 9 deletions
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26
fs/bcachefs/data_update.c
View File

@ -411,6 +411,7 @@ int bch2_data_update_init(struct btree_trans *trans,
const union bch_extent_entry *entry;
struct extent_ptr_decoded p;
unsigned i, reserve_sectors = k.k->size * data_opts.extra_replicas;
unsigned int ptrs_locked = 0;
int ret;
bch2_bkey_buf_init(&m->k);
@ -436,6 +437,8 @@ int bch2_data_update_init(struct btree_trans *trans,
i = 0;
bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
bool locked;
if (((1U << i) & m->data_opts.rewrite_ptrs) &&
p.ptr.cached)
BUG();
@ -461,11 +464,7 @@ int bch2_data_update_init(struct btree_trans *trans,
if (p.crc.compression_type == BCH_COMPRESSION_TYPE_incompressible)
m->op.incompressible = true;
i++;
if (ctxt) {
bool locked;
move_ctxt_wait_event(ctxt, trans,
(locked = bch2_bucket_nocow_trylock(&c->nocow_locks,
PTR_BUCKET_POS(c, &p.ptr), 0)) ||
@ -475,9 +474,14 @@ int bch2_data_update_init(struct btree_trans *trans,
bch2_bucket_nocow_lock(&c->nocow_locks,
PTR_BUCKET_POS(c, &p.ptr), 0);
} else {
bch2_bucket_nocow_lock(&c->nocow_locks,
PTR_BUCKET_POS(c, &p.ptr), 0);
if (!bch2_bucket_nocow_trylock(&c->nocow_locks,
PTR_BUCKET_POS(c, &p.ptr), 0)) {
ret = -BCH_ERR_nocow_lock_blocked;
goto err;
}
}
ptrs_locked |= (1U << i);
i++;
}
if (reserve_sectors) {
@ -499,9 +503,13 @@ int bch2_data_update_init(struct btree_trans *trans,
return -BCH_ERR_unwritten_extent_update;
return 0;
err:
bkey_for_each_ptr_decode(k.k, ptrs, p, entry)
bch2_bucket_nocow_unlock(&c->nocow_locks,
PTR_BUCKET_POS(c, &p.ptr), 0);
i = 0;
bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
if ((1U << i) & ptrs_locked)
bch2_bucket_nocow_unlock(&c->nocow_locks,
PTR_BUCKET_POS(c, &p.ptr), 0);
i++;
}
bch2_bkey_buf_exit(&m->k, c);
bch2_bio_free_pages_pool(c, &m->op.wbio.bio);

1
fs/bcachefs/errcode.h
View File

@ -120,6 +120,7 @@
x(BCH_ERR_invalid_sb, invalid_sb_clean) \
x(BCH_ERR_invalid_sb, invalid_sb_quota) \
x(BCH_ERR_invalid, invalid_bkey) \
x(BCH_ERR_operation_blocked, nocow_lock_blocked) \
enum bch_errcode {
BCH_ERR_START = 2048,

7
fs/bcachefs/io.c
View File

@ -2023,6 +2023,13 @@ static struct promote_op *__promote_alloc(struct btree_trans *trans,
.write_flags = BCH_WRITE_ALLOC_NOWAIT|BCH_WRITE_CACHED,
},
btree_id, k);
if (ret == -BCH_ERR_nocow_lock_blocked) {
ret = rhashtable_remove_fast(&c->promote_table, &op->hash,
bch_promote_params);
BUG_ON(ret);
goto err;
}
BUG_ON(ret);
op->write.op.end_io = promote_done;