[PATCH] fs/erofs: Fix build for m68k

[PATCH] fs/erofs: Fix build for m68k

[Daniel Palmer]

Currently the use of roundup() causes GCC to emit a reference
to __udivdi3() on m68k and we don't have that:

/usr/bin/m68k-linux-gnu-ld.bfd: fs/erofs/data.o: in function `erofs_map_blocks':
u-boot/fs/erofs/data.c:81:(.text.erofs_map_blocks+0x126): undefined reference to `__udivdi3'
/usr/bin/m68k-linux-gnu-ld.bfd: u-boot/fs/erofs/data.c:81:(.text.erofs_map_blocks+0x458): undefined reference to `__udivdi3'

We could add it but since unit is 4 or 8 we can actually just
switch the code to use round_up() instead and not output
__udivdi3() in the first place.

Signed-off-by: Daniel Palmer <daniel@thingy.jp>
---
 fs/erofs/data.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/erofs/data.c b/fs/erofs/data.c
index b58ec6fcc666..95873846f62d 100644
--- a/fs/erofs/data.c
+++ b/fs/erofs/data.c
@@ -78,7 +78,7 @@ int erofs_map_blocks(struct erofs_inode *inode,
 		unit = EROFS_BLOCK_MAP_ENTRY_SIZE;	/* block map */
 
 	chunknr = map->m_la >> vi->u.chunkbits;
-	pos = roundup(iloc(vi->nid) + vi->inode_isize +
+	pos = round_up(iloc(vi->nid) + vi->inode_isize +
 		      vi->xattr_isize, unit) + unit * chunknr;
 
 	err = erofs_blk_read(buf, erofs_blknr(pos), 1);
-- 
2.53.0

Re: [PATCH] fs/erofs: Fix build for m68k

[Kuan-Wei Chiu]

Hi Daniel,

On Sun, Apr 19, 2026 at 07:01:23PM +0900, Daniel Palmer wrote:
> Currently the use of roundup() causes GCC to emit a reference
> to __udivdi3() on m68k and we don't have that:
> 
> /usr/bin/m68k-linux-gnu-ld.bfd: fs/erofs/data.o: in function `erofs_map_blocks':
> u-boot/fs/erofs/data.c:81:(.text.erofs_map_blocks+0x126): undefined reference to `__udivdi3'
> /usr/bin/m68k-linux-gnu-ld.bfd: u-boot/fs/erofs/data.c:81:(.text.erofs_map_blocks+0x458): undefined reference to `__udivdi3'
> 
> We could add it but since unit is 4 or 8 we can actually just
> switch the code to use round_up() instead and not output
> __udivdi3() in the first place.
> 
> Signed-off-by: Daniel Palmer <daniel@thingy.jp>
> ---
>  fs/erofs/data.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/erofs/data.c b/fs/erofs/data.c
> index b58ec6fcc666..95873846f62d 100644
> --- a/fs/erofs/data.c
> +++ b/fs/erofs/data.c
> @@ -78,7 +78,7 @@ int erofs_map_blocks(struct erofs_inode *inode,
>  		unit = EROFS_BLOCK_MAP_ENTRY_SIZE;	/* block map */
>  
>  	chunknr = map->m_la >> vi->u.chunkbits;
> -	pos = roundup(iloc(vi->nid) + vi->inode_isize +
> +	pos = round_up(iloc(vi->nid) + vi->inode_isize +
>  		      vi->xattr_isize, unit) + unit * chunknr;

Since round_up(x, y) requires y to be a power of two, I was wondering
if it might be worth adding an assertion here to ensure this?

Additionally, a bit further down in erofs_map_blocks(), there is
another instance where roundup() is used. I haven't checked the
generated assembly, but I'm guessing it didn't fail because gcc was
smart enough to optimize it into a right shift? Since erofs_blksiz() is
defined as (1u << sbi.blkszbits), it is also guaranteed to be a power
of two. Perhaps we should replace that one with round_up() as well, for
safety and consistency?

Regards,
Kuan-Wei

>  
>  	err = erofs_blk_read(buf, erofs_blknr(pos), 1);
> -- 
> 2.53.0
> 

Re: [PATCH] fs/erofs: Fix build for m68k

[Daniel Palmer]

Hi Kuan-Wei,

On Sun, 26 Apr 2026 at 01:12, Kuan-Wei Chiu <visitorckw@gmail.com> wrote:
> Since round_up(x, y) requires y to be a power of two, I was wondering
> if it might be worth adding an assertion here to ensure this?

I think if we need that we should maybe wire it into round_up() so it
checks everything using it is passing a power of two.
I thought maybe the linux version had some compile time assert thing
but it doesn't seem to check either.

> Additionally, a bit further down in erofs_map_blocks(), there is
> another instance where roundup() is used. I haven't checked the
> generated assembly, but I'm guessing it didn't fail because gcc was
> smart enough to optimize it into a right shift? Since erofs_blksiz() is
> defined as (1u << sbi.blkszbits), it is also guaranteed to be a power
> of two. Perhaps we should replace that one with round_up() as well, for
> safety and consistency?

mmm maybe I should grep for all of the instances of roundup() in the
erofs code and fix them all at once.

Thanks,

Daniel