* [PATCH][next] bcachefs: Avoid -Wflex-array-member-not-at-end warning @ 2025-04-30 1:15 Gustavo A. R. Silva 2025-04-30 1:40 ` Kent Overstreet 0 siblings, 1 reply; 4+ messages in thread From: Gustavo A. R. Silva @ 2025-04-30 1:15 UTC (permalink / raw) To: Kent Overstreet Cc: linux-bcachefs, linux-kernel, Gustavo A. R. Silva, linux-hardening -Wflex-array-member-not-at-end was introduced in GCC-14, and we are getting ready to enable it, globally. Use the `DEFINE_FLEX()` helper for on-stack definitions 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/bcachefs/disk_accounting.c:429:51: 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 <gustavoars@kernel.org> --- fs/bcachefs/disk_accounting.c | 16 +++++++--------- 1 file changed, 7 insertions(+), 9 deletions(-) diff --git a/fs/bcachefs/disk_accounting.c b/fs/bcachefs/disk_accounting.c index 7be71952425c..381e666679d2 100644 --- a/fs/bcachefs/disk_accounting.c +++ b/fs/bcachefs/disk_accounting.c @@ -425,24 +425,22 @@ int bch2_fs_replicas_usage_read(struct bch_fs *c, darray_char *usage) percpu_down_read(&c->mark_lock); darray_for_each(acc->k, i) { - struct { - struct bch_replicas_usage r; - u8 pad[BCH_BKEY_PTRS_MAX]; - } u; + DEFINE_FLEX(struct bch_replicas_usage, u, r.devs, r.nr_devs, + BCH_BKEY_PTRS_MAX); - if (!accounting_to_replicas(&u.r.r, i->pos)) + if (!accounting_to_replicas(&u->r, i->pos)) continue; u64 sectors; bch2_accounting_mem_read_counters(acc, i - acc->k.data, §ors, 1, false); - u.r.sectors = sectors; + u->sectors = sectors; - ret = darray_make_room(usage, replicas_usage_bytes(&u.r)); + ret = darray_make_room(usage, replicas_usage_bytes(u)); if (ret) break; - memcpy(&darray_top(*usage), &u.r, replicas_usage_bytes(&u.r)); - usage->nr += replicas_usage_bytes(&u.r); + memcpy(&darray_top(*usage), u, replicas_usage_bytes(u)); + usage->nr += replicas_usage_bytes(u); } percpu_up_read(&c->mark_lock); -- 2.43.0 ^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH][next] bcachefs: Avoid -Wflex-array-member-not-at-end warning 2025-04-30 1:15 [PATCH][next] bcachefs: Avoid -Wflex-array-member-not-at-end warning Gustavo A. R. Silva @ 2025-04-30 1:40 ` Kent Overstreet 2025-04-30 18:27 ` Gustavo A. R. Silva 0 siblings, 1 reply; 4+ messages in thread From: Kent Overstreet @ 2025-04-30 1:40 UTC (permalink / raw) To: Gustavo A. R. Silva; +Cc: linux-bcachefs, linux-kernel, linux-hardening On Tue, Apr 29, 2025 at 07:15:37PM -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_FLEX()` helper for on-stack definitions 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/bcachefs/disk_accounting.c:429:51: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] We also have bch_replicas_padded, does that also need a fix? And, DEFINE_FLEX() is gross, can we try to stop reinventing language syntax with macros? Could we not have done this with an __attribute__(())? Or just swap the anonymous struct for a union, since that's apparently what DEFINE_FLEX() does? > > Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> > --- > fs/bcachefs/disk_accounting.c | 16 +++++++--------- > 1 file changed, 7 insertions(+), 9 deletions(-) > > diff --git a/fs/bcachefs/disk_accounting.c b/fs/bcachefs/disk_accounting.c > index 7be71952425c..381e666679d2 100644 > --- a/fs/bcachefs/disk_accounting.c > +++ b/fs/bcachefs/disk_accounting.c > @@ -425,24 +425,22 @@ int bch2_fs_replicas_usage_read(struct bch_fs *c, darray_char *usage) > > percpu_down_read(&c->mark_lock); > darray_for_each(acc->k, i) { > - struct { > - struct bch_replicas_usage r; > - u8 pad[BCH_BKEY_PTRS_MAX]; > - } u; > + DEFINE_FLEX(struct bch_replicas_usage, u, r.devs, r.nr_devs, > + BCH_BKEY_PTRS_MAX); > > - if (!accounting_to_replicas(&u.r.r, i->pos)) > + if (!accounting_to_replicas(&u->r, i->pos)) > continue; > > u64 sectors; > bch2_accounting_mem_read_counters(acc, i - acc->k.data, §ors, 1, false); > - u.r.sectors = sectors; > + u->sectors = sectors; > > - ret = darray_make_room(usage, replicas_usage_bytes(&u.r)); > + ret = darray_make_room(usage, replicas_usage_bytes(u)); > if (ret) > break; > > - memcpy(&darray_top(*usage), &u.r, replicas_usage_bytes(&u.r)); > - usage->nr += replicas_usage_bytes(&u.r); > + memcpy(&darray_top(*usage), u, replicas_usage_bytes(u)); > + usage->nr += replicas_usage_bytes(u); > } > percpu_up_read(&c->mark_lock); > > -- > 2.43.0 > ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH][next] bcachefs: Avoid -Wflex-array-member-not-at-end warning 2025-04-30 1:40 ` Kent Overstreet @ 2025-04-30 18:27 ` Gustavo A. R. Silva 2025-04-30 18:32 ` Kent Overstreet 0 siblings, 1 reply; 4+ messages in thread From: Gustavo A. R. Silva @ 2025-04-30 18:27 UTC (permalink / raw) To: Kent Overstreet, Gustavo A. R. Silva Cc: linux-bcachefs, linux-kernel, linux-hardening On 29/04/25 19:40, Kent Overstreet wrote: > On Tue, Apr 29, 2025 at 07:15:37PM -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_FLEX()` helper for on-stack definitions 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/bcachefs/disk_accounting.c:429:51: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] > > We also have bch_replicas_padded, does that also need a fix? Yes - so, how about the following to address both issues: diff --git a/fs/bcachefs/disk_accounting.c b/fs/bcachefs/disk_accounting.c index 7be71952425c..2dcccf1edbb9 100644 --- a/fs/bcachefs/disk_accounting.c +++ b/fs/bcachefs/disk_accounting.c @@ -287,7 +287,7 @@ static inline bool accounting_to_replicas(struct bch_replicas_entry_v1 *r, struc static int bch2_accounting_update_sb_one(struct bch_fs *c, struct bpos p) { - struct bch_replicas_padded r; + union bch_replicas_padded r; return accounting_to_replicas(&r.e, p) ? bch2_mark_replicas(c, &r.e) : 0; @@ -361,7 +361,7 @@ static int __bch2_accounting_mem_insert(struct bch_fs *c, struct bkey_s_c_accoun int bch2_accounting_mem_insert(struct bch_fs *c, struct bkey_s_c_accounting a, enum bch_accounting_mode mode) { - struct bch_replicas_padded r; + union bch_replicas_padded r; if (mode != BCH_ACCOUNTING_read && accounting_to_replicas(&r.e, a.k->p) && @@ -425,10 +425,12 @@ int bch2_fs_replicas_usage_read(struct bch_fs *c, darray_char *usage) percpu_down_read(&c->mark_lock); darray_for_each(acc->k, i) { - struct { + union { + u8 bytes[struct_size_t(struct bch_replicas_usage, r.devs, + BCH_BKEY_PTRS_MAX)]; struct bch_replicas_usage r; - u8 pad[BCH_BKEY_PTRS_MAX]; } u; + u.r.r.nr_devs = BCH_BKEY_PTRS_MAX; if (!accounting_to_replicas(&u.r.r, i->pos)) continue; @@ -627,7 +629,7 @@ static int bch2_disk_accounting_validate_late(struct btree_trans *trans, switch (acc->type) { case BCH_DISK_ACCOUNTING_replicas: { - struct bch_replicas_padded r; + union bch_replicas_padded r; __accounting_to_replicas(&r.e, acc); for (unsigned i = 0; i < r.e.nr_devs; i++) diff --git a/fs/bcachefs/ec_types.h b/fs/bcachefs/ec_types.h index 06144bfd9c19..809446c78951 100644 --- a/fs/bcachefs/ec_types.h +++ b/fs/bcachefs/ec_types.h @@ -4,9 +4,10 @@ #include "bcachefs_format.h" -struct bch_replicas_padded { +union bch_replicas_padded { + u8 bytes[struct_size_t(struct bch_replicas_entry_v1, + devs, BCH_BKEY_PTRS_MAX)]; struct bch_replicas_entry_v1 e; - u8 pad[BCH_BKEY_PTRS_MAX]; }; struct stripe { @@ -28,7 +29,7 @@ struct gc_stripe { u16 block_sectors[BCH_BKEY_PTRS_MAX]; struct bch_extent_ptr ptrs[BCH_BKEY_PTRS_MAX]; - struct bch_replicas_padded r; + union bch_replicas_padded r; }; #endif /* _BCACHEFS_EC_TYPES_H */ diff --git a/fs/bcachefs/journal_io.c b/fs/bcachefs/journal_io.c index 58e3983d860a..7c09a3c109ab 100644 --- a/fs/bcachefs/journal_io.c +++ b/fs/bcachefs/journal_io.c @@ -1404,7 +1404,7 @@ int bch2_journal_read(struct bch_fs *c, } genradix_for_each(&c->journal_entries, radix_iter, _i) { - struct bch_replicas_padded replicas = { + union bch_replicas_padded replicas = { .e.data_type = BCH_DATA_journal, .e.nr_devs = 0, .e.nr_required = 1, @@ -1632,7 +1632,7 @@ static CLOSURE_CALLBACK(journal_write_done) closure_type(w, struct journal_buf, io); struct journal *j = container_of(w, struct journal, buf[w->idx]); struct bch_fs *c = container_of(j, struct bch_fs, journal); - struct bch_replicas_padded replicas; + union bch_replicas_padded replicas; u64 seq = le64_to_cpu(w->data->seq); int err = 0; @@ -2055,7 +2055,7 @@ CLOSURE_CALLBACK(bch2_journal_write) closure_type(w, struct journal_buf, io); struct journal *j = container_of(w, struct journal, buf[w->idx]); struct bch_fs *c = container_of(j, struct bch_fs, journal); - struct bch_replicas_padded replicas; + union bch_replicas_padded replicas; unsigned nr_rw_members = dev_mask_nr(&c->rw_devs[BCH_DATA_journal]); int ret; diff --git a/fs/bcachefs/journal_reclaim.c b/fs/bcachefs/journal_reclaim.c index 66bfb95f1ea4..0acaf20f2181 100644 --- a/fs/bcachefs/journal_reclaim.c +++ b/fs/bcachefs/journal_reclaim.c @@ -953,7 +953,7 @@ int bch2_journal_flush_device_pins(struct journal *j, int dev_idx) seq = 0; spin_lock(&j->lock); while (!ret) { - struct bch_replicas_padded replicas; + union bch_replicas_padded replicas; seq = max(seq, journal_last_seq(j)); if (seq >= j->pin.back) Thanks -Gustavo ^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH][next] bcachefs: Avoid -Wflex-array-member-not-at-end warning 2025-04-30 18:27 ` Gustavo A. R. Silva @ 2025-04-30 18:32 ` Kent Overstreet 0 siblings, 0 replies; 4+ messages in thread From: Kent Overstreet @ 2025-04-30 18:32 UTC (permalink / raw) To: Gustavo A. R. Silva Cc: Gustavo A. R. Silva, linux-bcachefs, linux-kernel, linux-hardening On Wed, Apr 30, 2025 at 12:27:26PM -0600, Gustavo A. R. Silva wrote: > > > On 29/04/25 19:40, Kent Overstreet wrote: > > On Tue, Apr 29, 2025 at 07:15:37PM -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_FLEX()` helper for on-stack definitions 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/bcachefs/disk_accounting.c:429:51: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] > > > > We also have bch_replicas_padded, does that also need a fix? > > Yes - so, how about the following to address both issues: Yes, I like that much better > > diff --git a/fs/bcachefs/disk_accounting.c b/fs/bcachefs/disk_accounting.c > index 7be71952425c..2dcccf1edbb9 100644 > --- a/fs/bcachefs/disk_accounting.c > +++ b/fs/bcachefs/disk_accounting.c > @@ -287,7 +287,7 @@ static inline bool accounting_to_replicas(struct bch_replicas_entry_v1 *r, struc > > static int bch2_accounting_update_sb_one(struct bch_fs *c, struct bpos p) > { > - struct bch_replicas_padded r; > + union bch_replicas_padded r; > return accounting_to_replicas(&r.e, p) > ? bch2_mark_replicas(c, &r.e) > : 0; > @@ -361,7 +361,7 @@ static int __bch2_accounting_mem_insert(struct bch_fs *c, struct bkey_s_c_accoun > int bch2_accounting_mem_insert(struct bch_fs *c, struct bkey_s_c_accounting a, > enum bch_accounting_mode mode) > { > - struct bch_replicas_padded r; > + union bch_replicas_padded r; > > if (mode != BCH_ACCOUNTING_read && > accounting_to_replicas(&r.e, a.k->p) && > @@ -425,10 +425,12 @@ int bch2_fs_replicas_usage_read(struct bch_fs *c, darray_char *usage) > > percpu_down_read(&c->mark_lock); > darray_for_each(acc->k, i) { > - struct { > + union { > + u8 bytes[struct_size_t(struct bch_replicas_usage, r.devs, > + BCH_BKEY_PTRS_MAX)]; > struct bch_replicas_usage r; > - u8 pad[BCH_BKEY_PTRS_MAX]; > } u; > + u.r.r.nr_devs = BCH_BKEY_PTRS_MAX; > > if (!accounting_to_replicas(&u.r.r, i->pos)) > continue; > @@ -627,7 +629,7 @@ static int bch2_disk_accounting_validate_late(struct btree_trans *trans, > > switch (acc->type) { > case BCH_DISK_ACCOUNTING_replicas: { > - struct bch_replicas_padded r; > + union bch_replicas_padded r; > __accounting_to_replicas(&r.e, acc); > > for (unsigned i = 0; i < r.e.nr_devs; i++) > diff --git a/fs/bcachefs/ec_types.h b/fs/bcachefs/ec_types.h > index 06144bfd9c19..809446c78951 100644 > --- a/fs/bcachefs/ec_types.h > +++ b/fs/bcachefs/ec_types.h > @@ -4,9 +4,10 @@ > > #include "bcachefs_format.h" > > -struct bch_replicas_padded { > +union bch_replicas_padded { > + u8 bytes[struct_size_t(struct bch_replicas_entry_v1, > + devs, BCH_BKEY_PTRS_MAX)]; > struct bch_replicas_entry_v1 e; > - u8 pad[BCH_BKEY_PTRS_MAX]; > }; > > struct stripe { > @@ -28,7 +29,7 @@ struct gc_stripe { > u16 block_sectors[BCH_BKEY_PTRS_MAX]; > struct bch_extent_ptr ptrs[BCH_BKEY_PTRS_MAX]; > > - struct bch_replicas_padded r; > + union bch_replicas_padded r; > }; > > #endif /* _BCACHEFS_EC_TYPES_H */ > diff --git a/fs/bcachefs/journal_io.c b/fs/bcachefs/journal_io.c > index 58e3983d860a..7c09a3c109ab 100644 > --- a/fs/bcachefs/journal_io.c > +++ b/fs/bcachefs/journal_io.c > @@ -1404,7 +1404,7 @@ int bch2_journal_read(struct bch_fs *c, > } > > genradix_for_each(&c->journal_entries, radix_iter, _i) { > - struct bch_replicas_padded replicas = { > + union bch_replicas_padded replicas = { > .e.data_type = BCH_DATA_journal, > .e.nr_devs = 0, > .e.nr_required = 1, > @@ -1632,7 +1632,7 @@ static CLOSURE_CALLBACK(journal_write_done) > closure_type(w, struct journal_buf, io); > struct journal *j = container_of(w, struct journal, buf[w->idx]); > struct bch_fs *c = container_of(j, struct bch_fs, journal); > - struct bch_replicas_padded replicas; > + union bch_replicas_padded replicas; > u64 seq = le64_to_cpu(w->data->seq); > int err = 0; > > @@ -2055,7 +2055,7 @@ CLOSURE_CALLBACK(bch2_journal_write) > closure_type(w, struct journal_buf, io); > struct journal *j = container_of(w, struct journal, buf[w->idx]); > struct bch_fs *c = container_of(j, struct bch_fs, journal); > - struct bch_replicas_padded replicas; > + union bch_replicas_padded replicas; > unsigned nr_rw_members = dev_mask_nr(&c->rw_devs[BCH_DATA_journal]); > int ret; > > diff --git a/fs/bcachefs/journal_reclaim.c b/fs/bcachefs/journal_reclaim.c > index 66bfb95f1ea4..0acaf20f2181 100644 > --- a/fs/bcachefs/journal_reclaim.c > +++ b/fs/bcachefs/journal_reclaim.c > @@ -953,7 +953,7 @@ int bch2_journal_flush_device_pins(struct journal *j, int dev_idx) > seq = 0; > spin_lock(&j->lock); > while (!ret) { > - struct bch_replicas_padded replicas; > + union bch_replicas_padded replicas; > > seq = max(seq, journal_last_seq(j)); > if (seq >= j->pin.back) > > > Thanks > -Gustavo ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2025-04-30 18:32 UTC | newest] Thread overview: 4+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2025-04-30 1:15 [PATCH][next] bcachefs: Avoid -Wflex-array-member-not-at-end warning Gustavo A. R. Silva 2025-04-30 1:40 ` Kent Overstreet 2025-04-30 18:27 ` Gustavo A. R. Silva 2025-04-30 18:32 ` Kent Overstreet
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