From cd16edba1c6a24af138e1a5ded2711231fffa99f Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Thu, 4 Dec 2025 11:19:10 +0100 Subject: [PATCH] ext4: fix ext4_tune_sb_params padding The padding at the end of struct ext4_tune_sb_params is architecture specific and in particular is different between x86-32 and x86-64, since the __u64 member only enforces struct alignment on the latter. This shows up as a new warning when test-building the headers with -Wpadded: include/linux/ext4.h:144:1: error: padding struct size to alignment boundary with 4 bytes [-Werror=padded] All members inside the structure are naturally aligned, so the only difference here is the amount of padding at the end. Make the padding explicit, to have a consistent sizeof(struct ext4_tune_sb_params) of 232 on all architectures and avoid adding compat ioctl handling for EXT4_IOC_GET_TUNE_SB_PARAM/EXT4_IOC_SET_TUNE_SB_PARAM. This is an ABI break on x86-32 but hopefully this can go into 6.18.y early enough as a fixup so no actual users will be affected. Alternatively, the kernel could handle the ioctl commands for both sizes (232 and 228 bytes) on all architectures. Fixes: 04a91570ac67 ("ext4: implemet new ioctls to set and get superblock parameters") Signed-off-by: Arnd Bergmann Reviewed-by: Jan Kara Link: https://patch.msgid.link/20251204101914.1037148-1-arnd@kernel.org Signed-off-by: Theodore Ts'o Cc: stable@kernel.org --- include/uapi/linux/ext4.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/uapi/linux/ext4.h b/include/uapi/linux/ext4.h index 411dcc1e4a35c..9c683991c32f9 100644 --- a/include/uapi/linux/ext4.h +++ b/include/uapi/linux/ext4.h @@ -139,7 +139,7 @@ struct ext4_tune_sb_params { __u32 clear_feature_incompat_mask; __u32 clear_feature_ro_compat_mask; __u8 mount_opts[64]; - __u8 pad[64]; + __u8 pad[68]; }; #define EXT4_TUNE_FL_ERRORS_BEHAVIOR 0x00000001 -- 2.47.3