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.
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| @@ -139,7 +139,7 @@ struct ext4_tune_sb_params { · 138 unmodified lines | ||
| 139 | 139 | __u32 clear_feature_incompat_mask; |
| 140 | 140 | __u32 clear_feature_ro_compat_mask; |
| 141 | 141 | __u8 mount_opts[64]; |
| 142 | − __u8 pad[64]; | |
| 142 | + __u8 pad[68]; | |
| 143 | 143 | }; |
| 144 | 144 | |
| 145 | 145 | #define EXT4_TUNE_FL_ERRORS_BEHAVIOR 0x00000001 |