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bcachefs: Drop all btree locks when submitting btree node reads

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As a rule we don't want to be holding btree locks while submitting IO -
this will improve overall filesystem latency.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
This commit is contained in:
Kent Overstreet 2021-04-08 22:26:53 -04:00 committed by Kent Overstreet
parent 4351d3ecb4
commit c205321b12
2 changed files with 33 additions and 10 deletions
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39
fs/bcachefs/btree_cache.c
View File

@ -663,13 +663,9 @@ static noinline struct btree *bch2_btree_node_fill(struct bch_fs *c,
return NULL;
}
/*
* Unlock before doing IO:
*
* XXX: ideally should be dropping all btree node locks here
*/
if (iter && btree_node_read_locked(iter, level + 1))
btree_node_unlock(iter, level + 1);
/* Unlock before doing IO: */
if (iter && sync)
bch2_trans_unlock(iter->trans);
bch2_btree_node_read(c, b, sync);
@ -680,6 +676,16 @@ static noinline struct btree *bch2_btree_node_fill(struct bch_fs *c,
return NULL;
}
/*
* XXX: this will probably always fail because btree_iter_relock()
* currently fails for iterators that aren't pointed at a valid btree
* node
*/
if (iter && !bch2_trans_relock(iter->trans)) {
six_unlock_intent(&b->c.lock);
return ERR_PTR(-EINTR);
}
if (lock_type == SIX_LOCK_read)
six_lock_downgrade(&b->c.lock);
@ -824,9 +830,22 @@ lock_node:
}
}
/* XXX: waiting on IO with btree locks held: */
wait_on_bit_io(&b->flags, BTREE_NODE_read_in_flight,
TASK_UNINTERRUPTIBLE);
if (unlikely(btree_node_read_in_flight(b))) {
six_unlock_type(&b->c.lock, lock_type);
bch2_trans_unlock(iter->trans);
wait_on_bit_io(&b->flags, BTREE_NODE_read_in_flight,
TASK_UNINTERRUPTIBLE);
/*
* XXX: check if this always fails - btree_iter_relock()
* currently fails for iterators that aren't pointed at a valid
* btree node
*/
if (iter && !bch2_trans_relock(iter->trans))
return ERR_PTR(-EINTR);
goto retry;
}
prefetch(b->aux_data);

4
fs/bcachefs/btree_iter.c
View File

@ -1191,7 +1191,11 @@ static __always_inline int btree_iter_down(struct btree_iter *iter,
if (iter->flags & BTREE_ITER_PREFETCH)
btree_iter_prefetch(iter);
if (btree_node_read_locked(iter, level + 1))
btree_node_unlock(iter, level + 1);
iter->level = level;
bch2_btree_iter_verify_locks(iter);
err:
bch2_bkey_buf_exit(&tmp, c);
return ret;