On Tue, Jun 10, 2025 at 11:24:04AM +0200, Arnd Bergmann wrote:
> From: Arnd Bergmann <[email protected]>
>
> Multiple ioctl handlers individually use a lot of stack space, and clang
> chooses
> to inline them into the bch2_fs_ioctl() function, blowing through the warning
> limit:
>
> fs/bcachefs/chardev.c:655:6: error: stack frame size (1032) exceeds limit
> (1024) in 'bch2_fs_ioctl' [-Werror,-Wframe-larger-than]
> 655 | long bch2_fs_ioctl(struct bch_fs *c, unsigned cmd, void __user *arg)
>
> By marking the largest two of them as noinline_for_stack, no indidual code
> path
> ends up using this much, which avoids the warning and reduces the possible
> total stack usage in the ioctl handler.
>
> Signed-off-by: Arnd Bergmann <[email protected]>
Applied, thanks
> ---
> fs/bcachefs/chardev.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/bcachefs/chardev.c b/fs/bcachefs/chardev.c
> index 2d38466eddfd..fde3c2380e28 100644
> --- a/fs/bcachefs/chardev.c
> +++ b/fs/bcachefs/chardev.c
> @@ -399,7 +399,7 @@ static long bch2_ioctl_data(struct bch_fs *c,
> return ret;
> }
>
> -static long bch2_ioctl_fs_usage(struct bch_fs *c,
> +static noinline_for_stack long bch2_ioctl_fs_usage(struct bch_fs *c,
> struct bch_ioctl_fs_usage __user *user_arg)
> {
> struct bch_ioctl_fs_usage arg = {};
> @@ -469,7 +469,7 @@ static long bch2_ioctl_query_accounting(struct bch_fs *c,
> }
>
> /* obsolete, didn't allow for new data types: */
> -static long bch2_ioctl_dev_usage(struct bch_fs *c,
> +static noinline_for_stack long bch2_ioctl_dev_usage(struct bch_fs *c,
> struct bch_ioctl_dev_usage __user *user_arg)
> {
> struct bch_ioctl_dev_usage arg;
> --
> 2.39.5
>
