Re: [PATCH] ocfs2: reduce ioctl stack usage

Joseph Qi
2023-04-18T01:54:53Z

On 4/18/23 4:56 AM, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
>
> On 32-bit architectures with KASAN_STACK enabled, the total stack usage
> of the ocfs2_ioctl function grows beyond the warning limit:
>
> fs/ocfs2/ioctl.c: In function 'ocfs2_ioctl':
> fs/ocfs2/ioctl.c:934:1: error: the frame size of 1448 bytes is larger than 1400 bytes [-Werror=frame-larger-than=]
>
> Move each of the variables into a basic block, and mark ocfs2_info_handle()
> as noinline_for_stack, in order to have the variable share stack slots.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Looks good.

Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>

> ---
> fs/ocfs2/ioctl.c | 37 ++++++++++++++++++++++++++-----------
> 1 file changed, 26 insertions(+), 11 deletions(-)
>
> diff --git a/fs/ocfs2/ioctl.c b/fs/ocfs2/ioctl.c
> index 811a6ea374bb..b1550ba73f96 100644
> --- a/fs/ocfs2/ioctl.c
> +++ b/fs/ocfs2/ioctl.c
> @@ -803,8 +803,8 @@ static int ocfs2_get_request_ptr(struct ocfs2_info *info, int idx,
> * a better backward&forward compatibility, since a small piece of
> * request will be less likely to be broken if disk layout get changed.
> */
> -static int ocfs2_info_handle(struct inode *inode, struct ocfs2_info *info,
> - int compat_flag)
> +static noinline_for_stack int
> +ocfs2_info_handle(struct inode *inode, struct ocfs2_info *info, int compat_flag)
> {
> int i, status = 0;
> u64 req_addr;
> @@ -840,27 +840,26 @@ static int ocfs2_info_handle(struct inode *inode, struct ocfs2_info *info,
> long ocfs2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> {
> struct inode *inode = file_inode(filp);
> - int new_clusters;
> - int status;
> - struct ocfs2_space_resv sr;
> - struct ocfs2_new_group_input input;
> - struct reflink_arguments args;
> - const char __user *old_path;
> - const char __user *new_path;
> - bool preserve;
> - struct ocfs2_info info;
> void __user *argp = (void __user *)arg;
> + int status;
>
> switch (cmd) {
> case OCFS2_IOC_RESVSP:
> case OCFS2_IOC_RESVSP64:
> case OCFS2_IOC_UNRESVSP:
> case OCFS2_IOC_UNRESVSP64:
> + {
> + struct ocfs2_space_resv sr;
> +
> if (copy_from_user(&sr, (int __user *) arg, sizeof(sr)))
> return -EFAULT;
>
> return ocfs2_change_file_space(filp, cmd, &sr);
> + }
> case OCFS2_IOC_GROUP_EXTEND:
> + {
> + int new_clusters;
> +
> if (!capable(CAP_SYS_RESOURCE))
> return -EPERM;
>
> @@ -873,8 +872,12 @@ long ocfs2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> status = ocfs2_group_extend(inode, new_clusters);
> mnt_drop_write_file(filp);
> return status;
> + }
> case OCFS2_IOC_GROUP_ADD:
> case OCFS2_IOC_GROUP_ADD64:
> + {
> + struct ocfs2_new_group_input input;
> +
> if (!capable(CAP_SYS_RESOURCE))
> return -EPERM;
>
> @@ -887,7 +890,14 @@ long ocfs2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> status = ocfs2_group_add(inode, &input);
> mnt_drop_write_file(filp);
> return status;
> + }
> case OCFS2_IOC_REFLINK:
> + {
> + struct reflink_arguments args;
> + const char __user *old_path;
> + const char __user *new_path;
> + bool preserve;
> +
> if (copy_from_user(&args, argp, sizeof(args)))
> return -EFAULT;
> old_path = (const char __user *)(unsigned long)args.old_path;
> @@ -895,11 +905,16 @@ long ocfs2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> preserve = (args.preserve != 0);
>
> return ocfs2_reflink_ioctl(inode, old_path, new_path, preserve);
> + }
> case OCFS2_IOC_INFO:
> + {
> + struct ocfs2_info info;
> +
> if (copy_from_user(&info, argp, sizeof(struct ocfs2_info)))
> return -EFAULT;
>
> return ocfs2_info_handle(inode, &info, 0);
> + }
> case FITRIM:
> {
> struct super_block *sb = inode->i_sb;