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bcachefs: Refactor bch2_btree_node_mem_alloc()

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This is prep work for the next patch, which is going to fix our usage of
the percpu mode of six locks by never switching struct btree between the
two modes - which means we need separate freed lists.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
This commit is contained in:
Kent Overstreet 2022-03-04 19:50:28 -05:00 committed by Kent Overstreet
parent ee68105f61
commit 5b3f780540
1 changed files with 46 additions and 40 deletions
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86
fs/bcachefs/btree_cache.c
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@ -565,52 +565,54 @@ static struct btree *btree_node_cannibalize(struct bch_fs *c)
struct btree *bch2_btree_node_mem_alloc(struct bch_fs *c)
{
struct btree_cache *bc = &c->btree_cache;
struct btree *b;
struct btree *b, *b2;
u64 start_time = local_clock();
unsigned flags;
flags = memalloc_nofs_save();
mutex_lock(&bc->lock);
/*
* btree_free() doesn't free memory; it sticks the node on the end of
* the list. Check if there's any freed nodes there:
*/
list_for_each_entry(b, &bc->freeable, list)
if (!btree_node_reclaim(c, b))
goto got_node;
/*
* We never free struct btree itself, just the memory that holds the on
* disk node. Check the freed list before allocating a new one:
*/
list_for_each_entry(b, &bc->freed, list)
if (!btree_node_reclaim(c, b))
if (!btree_node_reclaim(c, b)) {
list_del_init(&b->list);
goto got_node;
}
b = NULL;
b = __btree_node_mem_alloc(c);
if (!b)
goto err_locked;
BUG_ON(!six_trylock_intent(&b->c.lock));
BUG_ON(!six_trylock_write(&b->c.lock));
got_node:
if (b)
list_del_init(&b->list);
/*
* btree_free() doesn't free memory; it sticks the node on the end of
* the list. Check if there's any freed nodes there:
*/
list_for_each_entry(b2, &bc->freeable, list)
if (!btree_node_reclaim(c, b2)) {
swap(b->data, b2->data);
swap(b->aux_data, b2->aux_data);
list_move(&b2->list, &bc->freed);
six_unlock_write(&b2->c.lock);
six_unlock_intent(&b2->c.lock);
goto got_mem;
}
mutex_unlock(&bc->lock);
if (!b) {
b = __btree_node_mem_alloc(c);
if (!b)
goto err;
if (btree_node_data_alloc(c, b, __GFP_NOWARN|GFP_KERNEL))
goto err;
BUG_ON(!six_trylock_intent(&b->c.lock));
BUG_ON(!six_trylock_write(&b->c.lock));
}
if (!b->data) {
if (btree_node_data_alloc(c, b, __GFP_NOWARN|GFP_KERNEL))
goto err;
mutex_lock(&bc->lock);
bc->used++;
mutex_unlock(&bc->lock);
}
mutex_lock(&bc->lock);
bc->used++;
got_mem:
mutex_unlock(&bc->lock);
BUG_ON(btree_node_hashed(b));
BUG_ON(btree_node_dirty(b));
@ -632,20 +634,24 @@ out:
return b;
err:
mutex_lock(&bc->lock);
if (b) {
list_add(&b->list, &bc->freed);
six_unlock_write(&b->c.lock);
six_unlock_intent(&b->c.lock);
}
err_locked:
/* Try to cannibalize another cached btree node: */
if (bc->alloc_lock == current) {
b = btree_node_cannibalize(c);
list_del_init(&b->list);
mutex_unlock(&bc->lock);
b2 = btree_node_cannibalize(c);
bch2_btree_node_hash_remove(bc, b2);
bch2_btree_node_hash_remove(bc, b);
if (b) {
swap(b->data, b2->data);
swap(b->aux_data, b2->aux_data);
list_move(&b2->list, &bc->freed);
six_unlock_write(&b2->c.lock);
six_unlock_intent(&b2->c.lock);
} else {
b = b2;
list_del_init(&b->list);
}
mutex_unlock(&bc->lock);
trace_btree_node_cannibalize(c);
goto out;