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bcache: Avoid -Wflex-array-member-not-at-end warning 

-Wflex-array-member-not-at-end was introduced in GCC-14, and we are
getting ready to enable it, globally.

Use the new TRAILING_OVERLAP() helper to fix the following warning:

drivers/md/bcache/bset.h:330:27: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]

This helper creates a union between a flexible-array member (FAM) and a
set of MEMBERS that would otherwise follow it.

This overlays the trailing MEMBER struct btree_iter_set stack_data[MAX_BSETS];
onto the FAM struct btree_iter::data[], while keeping the FAM and the start
of MEMBER aligned.

The static_assert() ensures this alignment remains, and it's
intentionally placed immediately after the corresponding structures --no
blank line in between.

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Coly Li <colyli@fnnas.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Gustavo A. R. Silva 2025-11-13 13:36:30 +08:00 committed by Jens Axboe
parent c0c8082142
commit 699122b590
1 changed files with 6 additions and 2 deletions
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8
drivers/md/bcache/bset.h
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@ -327,9 +327,13 @@ struct btree_iter {
/* Fixed-size btree_iter that can be allocated on the stack */
struct btree_iter_stack {
struct btree_iter iter;
struct btree_iter_set stack_data[MAX_BSETS];
/* Must be last as it ends in a flexible-array member. */
TRAILING_OVERLAP(struct btree_iter, iter, data,
struct btree_iter_set stack_data[MAX_BSETS];
);
};
static_assert(offsetof(struct btree_iter_stack, iter.data) ==
offsetof(struct btree_iter_stack, stack_data));
typedef bool (*ptr_filter_fn)(struct btree_keys *b, const struct bkey *k);