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bcachefs: Fix a deadlock on starting an interior btree update

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Not legal to block on a journal prereservation with btree locks held.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2020-04-05 21:49:17 -04:00 committed by Kent Overstreet
parent 1e3b1f9a22
commit 0f9dda478f
3 changed files with 32 additions and 18 deletions
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2
fs/bcachefs/btree_gc.c
View file

@ -935,7 +935,7 @@ static void bch2_coalesce_nodes(struct bch_fs *c, struct btree_iter *iter,
return;
}
as = bch2_btree_update_start(c, iter->btree_id,
as = bch2_btree_update_start(iter->trans, iter->btree_id,
btree_update_reserve_required(c, parent) + nr_old_nodes,
BTREE_INSERT_NOFAIL|
BTREE_INSERT_USE_RESERVE,

40
fs/bcachefs/btree_update_interior.c
View file

@ -949,14 +949,34 @@ void bch2_btree_update_done(struct btree_update *as)
}
struct btree_update *
bch2_btree_update_start(struct bch_fs *c, enum btree_id id,
bch2_btree_update_start(struct btree_trans *trans, enum btree_id id,
unsigned nr_nodes, unsigned flags,
struct closure *cl)
{
struct bch_fs *c = trans->c;
struct journal_preres journal_preres = { 0 };
struct btree_reserve *reserve;
struct btree_update *as;
int ret;
ret = bch2_journal_preres_get(&c->journal, &journal_preres,
BTREE_UPDATE_JOURNAL_RES,
JOURNAL_RES_GET_NONBLOCK);
if (ret == -EAGAIN) {
bch2_trans_unlock(trans);
ret = bch2_journal_preres_get(&c->journal, &journal_preres,
BTREE_UPDATE_JOURNAL_RES,
JOURNAL_RES_GET_NONBLOCK);
if (ret)
return ERR_PTR(ret);
if (!bch2_trans_relock(trans)) {
bch2_journal_preres_put(&c->journal, &journal_preres);
return ERR_PTR(-EINTR);
}
}
reserve = bch2_btree_reserve_get(c, nr_nodes, flags, cl);
if (IS_ERR(reserve))
return ERR_CAST(reserve);
@ -969,18 +989,10 @@ bch2_btree_update_start(struct bch_fs *c, enum btree_id id,
as->btree_id = id;
as->reserve = reserve;
INIT_LIST_HEAD(&as->write_blocked_list);
as->journal_preres = journal_preres;
bch2_keylist_init(&as->parent_keys, as->inline_keys);
ret = bch2_journal_preres_get(&c->journal, &as->journal_preres,
ARRAY_SIZE(as->journal_entries), 0);
if (ret) {
bch2_btree_reserve_put(c, reserve);
closure_debug_destroy(&as->cl);
mempool_free(as, &c->btree_interior_update_pool);
return ERR_PTR(ret);
}
mutex_lock(&c->btree_interior_update_lock);
list_add_tail(&as->list, &c->btree_interior_update_list);
mutex_unlock(&c->btree_interior_update_lock);
@ -1551,7 +1563,7 @@ int bch2_btree_split_leaf(struct bch_fs *c, struct btree_iter *iter,
goto out;
}
as = bch2_btree_update_start(c, iter->btree_id,
as = bch2_btree_update_start(trans, iter->btree_id,
btree_update_reserve_required(c, b), flags,
!(flags & BTREE_INSERT_NOUNLOCK) ? &cl : NULL);
if (IS_ERR(as)) {
@ -1663,7 +1675,7 @@ void __bch2_foreground_maybe_merge(struct bch_fs *c,
goto err_unlock;
}
as = bch2_btree_update_start(c, iter->btree_id,
as = bch2_btree_update_start(trans, iter->btree_id,
btree_update_reserve_required(c, parent) + 1,
BTREE_INSERT_NOFAIL|
BTREE_INSERT_USE_RESERVE,
@ -1776,7 +1788,7 @@ static int __btree_node_rewrite(struct bch_fs *c, struct btree_iter *iter,
struct btree *n, *parent = btree_node_parent(iter, b);
struct btree_update *as;
as = bch2_btree_update_start(c, iter->btree_id,
as = bch2_btree_update_start(iter->trans, iter->btree_id,
(parent
? btree_update_reserve_required(c, parent)
: 0) + 1,
@ -2043,7 +2055,7 @@ int bch2_btree_node_update_key(struct bch_fs *c, struct btree_iter *iter,
new_hash = bch2_btree_node_mem_alloc(c);
}
as = bch2_btree_update_start(c, iter->btree_id,
as = bch2_btree_update_start(iter->trans, iter->btree_id,
parent ? btree_update_reserve_required(c, parent) : 0,
BTREE_INSERT_NOFAIL|
BTREE_INSERT_USE_RESERVE|

8
fs/bcachefs/btree_update_interior.h
View file

@ -32,6 +32,9 @@ struct pending_btree_node_free {
__BKEY_PADDED(key, BKEY_BTREE_PTR_VAL_U64s_MAX);
};
#define BTREE_UPDATE_JOURNAL_RES \
((BKEY_BTREE_PTR_U64s_MAX + 1) * (BTREE_MAX_DEPTH - 1) * 2)
/*
* Tracks an in progress split/rewrite of a btree node and the update to the
* parent node:
@ -105,8 +108,7 @@ struct btree_update {
unsigned nr_new_nodes;
unsigned journal_u64s;
u64 journal_entries[
(BKEY_BTREE_PTR_U64s_MAX + 1) * (BTREE_MAX_DEPTH - 1) * 2];
u64 journal_entries[BTREE_UPDATE_JOURNAL_RES];
/* Only here to reduce stack usage on recursive splits: */
struct keylist parent_keys;
@ -132,7 +134,7 @@ struct btree *__bch2_btree_node_alloc_replacement(struct btree_update *,
void bch2_btree_update_done(struct btree_update *);
struct btree_update *
bch2_btree_update_start(struct bch_fs *, enum btree_id, unsigned,
bch2_btree_update_start(struct btree_trans *, enum btree_id, unsigned,
unsigned, struct closure *);
void bch2_btree_interior_update_will_free_node(struct btree_update *,