On Wed, Mar 26, 2025 at 04:55:51PM -0600, Gustavo A. R. Silva wrote: > -Wflex-array-member-not-at-end was introduced in GCC-14, and we are > getting ready to enable it, globally. > > Use the `DEFINE_RAW_FLEX()` helper for an on-stack definition of > a flexible structure where the size of the flexible-array member > is known at compile-time, and refactor the rest of the code, > accordingly. > > So, with these changes, fix the following warning: > > fs/ext4/mballoc.c:3041:40: warning: structure containing a flexible array > member is not at the end of another structure [-Wflex-array-member-not-at-end] > > Signed-off-by: Gustavo A. R. Silva <[email protected]> > --- > fs/ext4/mballoc.c | 18 ++++++++---------- > 1 file changed, 8 insertions(+), 10 deletions(-) > > diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c > index 0d523e9fb3d5..f88424c28194 100644 > --- a/fs/ext4/mballoc.c > +++ b/fs/ext4/mballoc.c > @@ -3037,10 +3037,8 @@ static int ext4_mb_seq_groups_show(struct seq_file > *seq, void *v) > unsigned char blocksize_bits = min_t(unsigned char, > sb->s_blocksize_bits, > EXT4_MAX_BLOCK_LOG_SIZE); > - struct sg { > - struct ext4_group_info info; > - ext4_grpblk_t counters[EXT4_MAX_BLOCK_LOG_SIZE + 2]; > - } sg; > + DEFINE_RAW_FLEX(struct ext4_group_info, sg, bb_counters, > + EXT4_MAX_BLOCK_LOG_SIZE + 2);
Yup, struct ext4_group_info::bb_counters is ext4_grpblk_t, so everything matches up. > > group--; > if (group == 0) > @@ -3048,7 +3046,7 @@ static int ext4_mb_seq_groups_show(struct seq_file > *seq, void *v) > " 2^0 2^1 2^2 2^3 2^4 2^5 2^6 " > " 2^7 2^8 2^9 2^10 2^11 2^12 2^13 ]\n"); > > - i = (blocksize_bits + 2) * sizeof(sg.info.bb_counters[0]) + > + i = (blocksize_bits + 2) * sizeof(sg->bb_counters[0]) + > sizeof(struct ext4_group_info); > > grinfo = ext4_get_group_info(sb, group); > @@ -3068,14 +3066,14 @@ static int ext4_mb_seq_groups_show(struct seq_file > *seq, void *v) > * We care only about free space counters in the group info and > * these are safe to access even after the buddy has been unloaded > */ > - memcpy(&sg, grinfo, i); > - seq_printf(seq, "#%-5u: %-5u %-5u %-5u [", group, sg.info.bb_free, > - sg.info.bb_fragments, sg.info.bb_first_free); > + memcpy(sg, grinfo, i); > + seq_printf(seq, "#%-5u: %-5u %-5u %-5u [", group, sg->bb_free, > + sg->bb_fragments, sg->bb_first_free); > for (i = 0; i <= 13; i++) > seq_printf(seq, " %-5u", i <= blocksize_bits + 1 ? > - sg.info.bb_counters[i] : 0); > + sg->bb_counters[i] : 0); > seq_puts(seq, " ]"); > - if (EXT4_MB_GRP_BBITMAP_CORRUPT(&sg.info)) > + if (EXT4_MB_GRP_BBITMAP_CORRUPT(sg)) > seq_puts(seq, " Block bitmap corrupted!"); > seq_putc(seq, '\n'); > return 0; Replacements looks good. Reviewed-by: Kees Cook <[email protected]> -- Kees Cook
