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bcachefs: Use mmap() instead of vmalloc_exec() in userspace

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Calling mmap() directly is much better than malloc() then mprotect(), we
end up with much less address space fragmentation.

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 2021-04-24 00:38:16 -04:00 committed by Kent Overstreet
parent 537c32f521
commit 65c0601a32
1 changed files with 19 additions and 12 deletions
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31
fs/bcachefs/btree_cache.c
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@ -33,21 +33,21 @@ static inline unsigned btree_cache_can_free(struct btree_cache *bc)
return max_t(int, 0, bc->used - bc->reserve);
}
static void __btree_node_data_free(struct bch_fs *c, struct btree *b)
{
EBUG_ON(btree_node_write_in_flight(b));
kvpfree(b->data, btree_bytes(c));
b->data = NULL;
kvfree(b->aux_data);
b->aux_data = NULL;
}
static void btree_node_data_free(struct bch_fs *c, struct btree *b)
{
struct btree_cache *bc = &c->btree_cache;
__btree_node_data_free(c, b);
EBUG_ON(btree_node_write_in_flight(b));
kvpfree(b->data, btree_bytes(c));
b->data = NULL;
#ifdef __KERNEL__
kvfree(b->aux_data);
#else
munmap(b->aux_data, btree_aux_data_bytes(b));
#endif
b->aux_data = NULL;
bc->used--;
list_move(&b->list, &bc->freed);
}
@ -75,8 +75,15 @@ static int btree_node_data_alloc(struct bch_fs *c, struct btree *b, gfp_t gfp)
b->data = kvpmalloc(btree_bytes(c), gfp);
if (!b->data)
return -ENOMEM;
#ifdef __KERNEL__
b->aux_data = kvmalloc(btree_aux_data_bytes(b), gfp);
#else
b->aux_data = mmap(NULL, btree_aux_data_bytes(b),
PROT_READ|PROT_WRITE|PROT_EXEC,
MAP_PRIVATE|MAP_ANONYMOUS, 0, 0);
if (b->aux_data == MAP_FAILED)
b->aux_data = NULL;
#endif
if (!b->aux_data) {
kvpfree(b->data, btree_bytes(c));
b->data = NULL;