On Tue, Sep 25, 2018 at 08:06:26AM +0800, Qu Wenruo wrote:
> Although BTRFS_NAME_LEN and XATTR_NAME_MAX is the same value (255),
> max(BTRFS_NAME_LEN, XATTR_NAME_MAX) should be optimized as const at
> runtime.
>
> However S390x' arch dependent option "-mwarn-dynamicstack" could still
> report it as dyanamic stack allocation.
>
> Just use BTRFS_NAME_LEN directly to avoid such false alert.
Same reasoning as for the NAME_MAX, these are different things.
> Signed-off-by: Qu Wenruo <w...@suse.com>
> ---
> fs/btrfs/tree-checker.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
> index db835635372f..4c045609909b 100644
> --- a/fs/btrfs/tree-checker.c
> +++ b/fs/btrfs/tree-checker.c
> @@ -336,7 +336,7 @@ static int check_dir_item(struct btrfs_fs_info *fs_info,
> */
> if (key->type == BTRFS_DIR_ITEM_KEY ||
> key->type == BTRFS_XATTR_ITEM_KEY) {
> - char namebuf[max(BTRFS_NAME_LEN, XATTR_NAME_MAX)];
> + char namebuf[BTRFS_NAME_LEN];
The updated implementation of max() can now handle the expression
without a warning, with sufficiently new compiler so I don't think we
need to fix that.
Alternatively, you could use BTRFS_NAME_LEN and add a
BUILD_BUG_ON(BTRFS_NAME_LEN < XATTR_NAME_MAX) with a comment why.
>
> read_extent_buffer(leaf, namebuf,
> (unsigned long)(di + 1), name_len);
> --
> 2.19.0
