With the change to make inode->i_ino a u64, the build started failing on
32-bit ARM with:
ERROR: modpost: "__aeabi_uldivmod" [fs/nilfs2/nilfs2.ko] undefined!
Fix this by using the 64-bit division interfaces in
nilfs_bmap_find_target_in_group().
Fixes: 998a59d371c2 ("treewide: fix missed i_ino format specifier conversions")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202603100602.KPxiClIO-lkp@intel.com/
Reviewed-by: Viacheslav Dubeyko <slava@dubeyko.com>
Acked-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
fs/nilfs2/bmap.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/fs/nilfs2/bmap.c b/fs/nilfs2/bmap.c
index 824f2bd91c167965ec3a660202b6e6c5f1fe007e..abcf5252578ad24f694bfccf525893674bfcb4bc 100644
--- a/fs/nilfs2/bmap.c
+++ b/fs/nilfs2/bmap.c
@@ -455,11 +455,14 @@ __u64 nilfs_bmap_find_target_in_group(const struct nilfs_bmap *bmap)
{
struct inode *dat = nilfs_bmap_get_dat(bmap);
unsigned long entries_per_group = nilfs_palloc_entries_per_group(dat);
- unsigned long group = bmap->b_inode->i_ino / entries_per_group;
+ unsigned long group;
+ u32 index;
+
+ group = div_u64(bmap->b_inode->i_ino, entries_per_group);
+ div_u64_rem(bmap->b_inode->i_ino, NILFS_BMAP_GROUP_DIV, &index);
return group * entries_per_group +
- (bmap->b_inode->i_ino % NILFS_BMAP_GROUP_DIV) *
- (entries_per_group / NILFS_BMAP_GROUP_DIV);
+ index * (entries_per_group / NILFS_BMAP_GROUP_DIV);
}
static struct lock_class_key nilfs_bmap_dat_lock_key;
--
2.53.0On Fri, 13 Mar 2026 14:45:20 -0400
Jeff Layton <jlayton@kernel.org> wrote:
> With the change to make inode->i_ino a u64, the build started failing on
> 32-bit ARM with:
>
> ERROR: modpost: "__aeabi_uldivmod" [fs/nilfs2/nilfs2.ko] undefined!
>
> Fix this by using the 64-bit division interfaces in
> nilfs_bmap_find_target_in_group().
>
> Fixes: 998a59d371c2 ("treewide: fix missed i_ino format specifier conversions")
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202603100602.KPxiClIO-lkp@intel.com/
> Reviewed-by: Viacheslav Dubeyko <slava@dubeyko.com>
> Acked-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
> Signed-off-by: Jeff Layton <jlayton@kernel.org>
> ---
> fs/nilfs2/bmap.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/fs/nilfs2/bmap.c b/fs/nilfs2/bmap.c
> index 824f2bd91c167965ec3a660202b6e6c5f1fe007e..abcf5252578ad24f694bfccf525893674bfcb4bc 100644
> --- a/fs/nilfs2/bmap.c
> +++ b/fs/nilfs2/bmap.c
> @@ -455,11 +455,14 @@ __u64 nilfs_bmap_find_target_in_group(const struct nilfs_bmap *bmap)
> {
> struct inode *dat = nilfs_bmap_get_dat(bmap);
> unsigned long entries_per_group = nilfs_palloc_entries_per_group(dat);
> - unsigned long group = bmap->b_inode->i_ino / entries_per_group;
Are you sure entries_per_group can be more than 32 bits?
It looks like something that will be the same size on 32 and 64bit.
> + unsigned long group;
> + u32 index;
> +
> + group = div_u64(bmap->b_inode->i_ino, entries_per_group);
You don't need the full 64 by 64 divide.
IIRC there are both div_u64_u32() and div_u64_ulong().
> + div_u64_rem(bmap->b_inode->i_ino, NILFS_BMAP_GROUP_DIV, &index);
NILFD_BMAP_GROUP_DIV is 8 (and probably has to be a power of 2).
So:
index = bmap->b_inode->i_ino & (NILFS_BMAP_GROUP_DIV - 1);
is the same and likely much faster to calculate.
(The compiler will have done that optimisation before.)
David
>
> return group * entries_per_group +
> - (bmap->b_inode->i_ino % NILFS_BMAP_GROUP_DIV) *
> - (entries_per_group / NILFS_BMAP_GROUP_DIV);
> + index * (entries_per_group / NILFS_BMAP_GROUP_DIV);
> }
>
> static struct lock_class_key nilfs_bmap_dat_lock_key;
>
On Sat, 2026-03-14 at 12:47 +0000, David Laight wrote:
> On Fri, 13 Mar 2026 14:45:20 -0400
> Jeff Layton <jlayton@kernel.org> wrote:
>
> > With the change to make inode->i_ino a u64, the build started failing on
> > 32-bit ARM with:
> >
> > ERROR: modpost: "__aeabi_uldivmod" [fs/nilfs2/nilfs2.ko] undefined!
> >
> > Fix this by using the 64-bit division interfaces in
> > nilfs_bmap_find_target_in_group().
> >
> > Fixes: 998a59d371c2 ("treewide: fix missed i_ino format specifier conversions")
> > Reported-by: kernel test robot <lkp@intel.com>
> > Closes: https://lore.kernel.org/oe-kbuild-all/202603100602.KPxiClIO-lkp@intel.com/
> > Reviewed-by: Viacheslav Dubeyko <slava@dubeyko.com>
> > Acked-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
> > Signed-off-by: Jeff Layton <jlayton@kernel.org>
> > ---
> > fs/nilfs2/bmap.c | 9 ++++++---
> > 1 file changed, 6 insertions(+), 3 deletions(-)
> >
> > diff --git a/fs/nilfs2/bmap.c b/fs/nilfs2/bmap.c
> > index 824f2bd91c167965ec3a660202b6e6c5f1fe007e..abcf5252578ad24f694bfccf525893674bfcb4bc 100644
> > --- a/fs/nilfs2/bmap.c
> > +++ b/fs/nilfs2/bmap.c
> > @@ -455,11 +455,14 @@ __u64 nilfs_bmap_find_target_in_group(const struct nilfs_bmap *bmap)
> > {
> > struct inode *dat = nilfs_bmap_get_dat(bmap);
> > unsigned long entries_per_group = nilfs_palloc_entries_per_group(dat);
> > - unsigned long group = bmap->b_inode->i_ino / entries_per_group;
>
> Are you sure entries_per_group can be more than 32 bits?
> It looks like something that will be the same size on 32 and 64bit.
>
I'm not sure of anything here. I'm just want to get this to compile on
all arches. FWIW, I'm not looking to optimize anything in this patch.
> > + unsigned long group;
> > + u32 index;
> > +
> > + group = div_u64(bmap->b_inode->i_ino, entries_per_group);
>
> You don't need the full 64 by 64 divide.
> IIRC there are both div_u64_u32() and div_u64_ulong().
>
> > + div_u64_rem(bmap->b_inode->i_ino, NILFS_BMAP_GROUP_DIV, &index);
>
> NILFD_BMAP_GROUP_DIV is 8 (and probably has to be a power of 2).
> So:
> index = bmap->b_inode->i_ino & (NILFS_BMAP_GROUP_DIV - 1);
> is the same and likely much faster to calculate.
> (The compiler will have done that optimisation before.)
>
>
That all sounds reasonable to me. At this point though, it would be
better if the NILFS2 folks stepped in with how they'd prefer this be
done.
>
> >
> > return group * entries_per_group +
> > - (bmap->b_inode->i_ino % NILFS_BMAP_GROUP_DIV) *
> > - (entries_per_group / NILFS_BMAP_GROUP_DIV);
> > + index * (entries_per_group / NILFS_BMAP_GROUP_DIV);
> > }
> >
> > static struct lock_class_key nilfs_bmap_dat_lock_key;
> >
--
Jeff Layton <jlayton@kernel.org>
On Sat, Mar 14, 2026 at 9:59 PM Jeff Layton wrote:
>
> On Sat, 2026-03-14 at 12:47 +0000, David Laight wrote:
> > On Fri, 13 Mar 2026 14:45:20 -0400
> > Jeff Layton <jlayton@kernel.org> wrote:
> >
> > > With the change to make inode->i_ino a u64, the build started failing on
> > > 32-bit ARM with:
> > >
> > > ERROR: modpost: "__aeabi_uldivmod" [fs/nilfs2/nilfs2.ko] undefined!
> > >
> > > Fix this by using the 64-bit division interfaces in
> > > nilfs_bmap_find_target_in_group().
> > >
> > > Fixes: 998a59d371c2 ("treewide: fix missed i_ino format specifier conversions")
> > > Reported-by: kernel test robot <lkp@intel.com>
> > > Closes: https://lore.kernel.org/oe-kbuild-all/202603100602.KPxiClIO-lkp@intel.com/
> > > Reviewed-by: Viacheslav Dubeyko <slava@dubeyko.com>
> > > Acked-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
> > > Signed-off-by: Jeff Layton <jlayton@kernel.org>
> > > ---
> > > fs/nilfs2/bmap.c | 9 ++++++---
> > > 1 file changed, 6 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/fs/nilfs2/bmap.c b/fs/nilfs2/bmap.c
> > > index 824f2bd91c167965ec3a660202b6e6c5f1fe007e..abcf5252578ad24f694bfccf525893674bfcb4bc 100644
> > > --- a/fs/nilfs2/bmap.c
> > > +++ b/fs/nilfs2/bmap.c
> > > @@ -455,11 +455,14 @@ __u64 nilfs_bmap_find_target_in_group(const struct nilfs_bmap *bmap)
> > > {
> > > struct inode *dat = nilfs_bmap_get_dat(bmap);
> > > unsigned long entries_per_group = nilfs_palloc_entries_per_group(dat);
> > > - unsigned long group = bmap->b_inode->i_ino / entries_per_group;
> >
> > Are you sure entries_per_group can be more than 32 bits?
> > It looks like something that will be the same size on 32 and 64bit.
> >
>
> I'm not sure of anything here. I'm just want to get this to compile on
> all arches. FWIW, I'm not looking to optimize anything in this patch.
>
> > > + unsigned long group;
> > > + u32 index;
> > > +
> > > + group = div_u64(bmap->b_inode->i_ino, entries_per_group);
> >
> > You don't need the full 64 by 64 divide.
> > IIRC there are both div_u64_u32() and div_u64_ulong().
Isn't the type of divisor in div_u64() u32?
Since entries_per_group cannot exceed 32 bits according to the current
specification, I think using div_u64() is fine.
> >
> > > + div_u64_rem(bmap->b_inode->i_ino, NILFS_BMAP_GROUP_DIV, &index);
> >
> > NILFD_BMAP_GROUP_DIV is 8 (and probably has to be a power of 2).
> > So:
> > index = bmap->b_inode->i_ino & (NILFS_BMAP_GROUP_DIV - 1);
> > is the same and likely much faster to calculate.
> > (The compiler will have done that optimisation before.)
> >
> >
>
> That all sounds reasonable to me. At this point though, it would be
> better if the NILFS2 folks stepped in with how they'd prefer this be
> done.
Yes, indeed. It seems that the application of optimizations will
change, so this proposed correction is better.
Since NILFS_BMAP_GROUP_DIV is a fixed constant and cannot be anything
other than a power of 2, could you please adopt this proposed
correction with the following comment?
#define NILFS_BMAP_GROUP_DIV 8 /* must be a power of 2 */
Thanks,
Ryusuke Konishi
>
> >
> > >
> > > return group * entries_per_group +
> > > - (bmap->b_inode->i_ino % NILFS_BMAP_GROUP_DIV) *
> > > - (entries_per_group / NILFS_BMAP_GROUP_DIV);
> > > + index * (entries_per_group / NILFS_BMAP_GROUP_DIV);
> > > }
> > >
> > > static struct lock_class_key nilfs_bmap_dat_lock_key;
> > >
>
> --
> Jeff Layton <jlayton@kernel.org>
On Tue, 2026-03-17 at 03:06 +0900, Ryusuke Konishi wrote:
> On Sat, Mar 14, 2026 at 9:59 PM Jeff Layton wrote:
> >
> > On Sat, 2026-03-14 at 12:47 +0000, David Laight wrote:
> > > On Fri, 13 Mar 2026 14:45:20 -0400
> > > Jeff Layton <jlayton@kernel.org> wrote:
> > >
> > > > With the change to make inode->i_ino a u64, the build started failing on
> > > > 32-bit ARM with:
> > > >
> > > > ERROR: modpost: "__aeabi_uldivmod" [fs/nilfs2/nilfs2.ko] undefined!
> > > >
> > > > Fix this by using the 64-bit division interfaces in
> > > > nilfs_bmap_find_target_in_group().
> > > >
> > > > Fixes: 998a59d371c2 ("treewide: fix missed i_ino format specifier conversions")
> > > > Reported-by: kernel test robot <lkp@intel.com>
> > > > Closes: https://lore.kernel.org/oe-kbuild-all/202603100602.KPxiClIO-lkp@intel.com/
> > > > Reviewed-by: Viacheslav Dubeyko <slava@dubeyko.com>
> > > > Acked-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
> > > > Signed-off-by: Jeff Layton <jlayton@kernel.org>
> > > > ---
> > > > fs/nilfs2/bmap.c | 9 ++++++---
> > > > 1 file changed, 6 insertions(+), 3 deletions(-)
> > > >
> > > > diff --git a/fs/nilfs2/bmap.c b/fs/nilfs2/bmap.c
> > > > index 824f2bd91c167965ec3a660202b6e6c5f1fe007e..abcf5252578ad24f694bfccf525893674bfcb4bc 100644
> > > > --- a/fs/nilfs2/bmap.c
> > > > +++ b/fs/nilfs2/bmap.c
> > > > @@ -455,11 +455,14 @@ __u64 nilfs_bmap_find_target_in_group(const struct nilfs_bmap *bmap)
> > > > {
> > > > struct inode *dat = nilfs_bmap_get_dat(bmap);
> > > > unsigned long entries_per_group = nilfs_palloc_entries_per_group(dat);
> > > > - unsigned long group = bmap->b_inode->i_ino / entries_per_group;
> > >
> > > Are you sure entries_per_group can be more than 32 bits?
> > > It looks like something that will be the same size on 32 and 64bit.
> > >
> >
> > I'm not sure of anything here. I'm just want to get this to compile on
> > all arches. FWIW, I'm not looking to optimize anything in this patch.
> >
> > > > + unsigned long group;
> > > > + u32 index;
> > > > +
> > > > + group = div_u64(bmap->b_inode->i_ino, entries_per_group);
> > >
> > > You don't need the full 64 by 64 divide.
> > > IIRC there are both div_u64_u32() and div_u64_ulong().
>
> Isn't the type of divisor in div_u64() u32?
> Since entries_per_group cannot exceed 32 bits according to the current
> specification, I think using div_u64() is fine.
>
Yep, it is:
static inline u64 div_u64(u64 dividend, u32 divisor)
> > >
> > > > + div_u64_rem(bmap->b_inode->i_ino, NILFS_BMAP_GROUP_DIV, &index);
> > >
> > > NILFD_BMAP_GROUP_DIV is 8 (and probably has to be a power of 2).
> > > So:
> > > index = bmap->b_inode->i_ino & (NILFS_BMAP_GROUP_DIV - 1);
> > > is the same and likely much faster to calculate.
> > > (The compiler will have done that optimisation before.)
> > >
> > >
> >
> > That all sounds reasonable to me. At this point though, it would be
> > better if the NILFS2 folks stepped in with how they'd prefer this be
> > done.
>
> Yes, indeed. It seems that the application of optimizations will
> change, so this proposed correction is better.
>
> Since NILFS_BMAP_GROUP_DIV is a fixed constant and cannot be anything
> other than a power of 2, could you please adopt this proposed
> correction with the following comment?
>
> #define NILFS_BMAP_GROUP_DIV 8 /* must be a power of 2 */
>
Even better, lets use a compile-time assertion:
BUILD_BUG_ON_NOT_POWER_OF_TWO(NILFS_BMAP_GROUP_DIV);
I'll send a respin.
Thanks!
--
Jeff Layton <jlayton@kernel.org>
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