From: Kees Cook Date: Fri, 23 Sep 2022 20:28:13 +0000 (-0700) Subject: btrfs: send: Proactively round up to kmalloc bucket size X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=905889bc6c842d18f369bf2834cf7219f32709ae;p=linux.git btrfs: send: Proactively round up to kmalloc bucket size Instead of discovering the kmalloc bucket size _after_ allocation, round up proactively so the allocation is explicitly made for the full size, allowing the compiler to correctly reason about the resulting size of the buffer through the existing __alloc_size() hint. Cc: Chris Mason Cc: Josef Bacik Cc: linux-btrfs@vger.kernel.org Acked-by: David Sterba Link: https://lore.kernel.org/lkml/20220922133014.GI32411@suse.cz Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20220923202822.2667581-8-keescook@chromium.org --- diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c index 4ef4167072b89..f53e8049473dd 100644 --- a/fs/btrfs/send.c +++ b/fs/btrfs/send.c @@ -438,6 +438,11 @@ static int fs_path_ensure_buf(struct fs_path *p, int len) path_len = p->end - p->start; old_buf_len = p->buf_len; + /* + * Allocate to the next largest kmalloc bucket size, to let + * the fast path happen most of the time. + */ + len = kmalloc_size_roundup(len); /* * First time the inline_buf does not suffice */ @@ -451,11 +456,7 @@ static int fs_path_ensure_buf(struct fs_path *p, int len) if (!tmp_buf) return -ENOMEM; p->buf = tmp_buf; - /* - * The real size of the buffer is bigger, this will let the fast path - * happen most of the time - */ - p->buf_len = ksize(p->buf); + p->buf_len = len; if (p->reversed) { tmp_buf = p->buf + old_buf_len - path_len - 1;