[PATCH] bcachefs: Avoid a potential memory over-allocation in bch2_printbuf_make_room()

Christophe JAILLET
2023-09-16T08:46:14Z

kmalloc() and co. don't always allocate a power of 2 number of bytes.
There are some special handling for 64<n<=96 and 128<n<=192 cases.

So trust kmalloc() algorithm instead of forcing a power of 2 allocation.
This can saves a few bytes of memory and still make use of all the
memory allocated.

On the other side, it may require an additional realloc() in some cases.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
fs/bcachefs/printbuf.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/bcachefs/printbuf.c b/fs/bcachefs/printbuf.c
index 77bee9060bfe..34527407e950 100644
--- a/fs/bcachefs/printbuf.c
+++ b/fs/bcachefs/printbuf.c
@@ -28,7 +28,7 @@ int bch2_printbuf_make_room(struct printbuf *out, unsigned extra)
if (out->pos + extra < out->size)
return 0;

- new_size = roundup_pow_of_two(out->size + extra);
+ new_size = kmalloc_size_roundup(out->size + extra);

/*
* Note: output buffer must be freeable with kfree(), it's not required
--
2.34.1