Re: [PATCH v2 3/7] buffer: Fix grow_buffers() for block size > PAGE_SIZE

[Andrew Morton <akpm@linux-foundation.org>]

On Sun, 12 Nov 2023 12:52:00 +0800 kernel test robot <lkp@intel.com> wrote:

> Hi Matthew,
> 
> kernel test robot noticed the following build errors:
> 
> [auto build test ERROR on akpm-mm/mm-everything]
> [also build test ERROR on linus/master next-20231110]
> [cannot apply to v6.6]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch#_base_tree_information]
> 
> url:    https://github.com/intel-lab-lkp/linux/commits/Matthew-Wilcox-Oracle/buffer-Return-bool-from-grow_dev_folio/20231110-051651
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
> patch link:    https://lore.kernel.org/r/20231109210608.2252323-4-willy%40infradead.org
> patch subject: [PATCH v2 3/7] buffer: Fix grow_buffers() for block size > PAGE_SIZE
> config: hexagon-comet_defconfig (https://download.01.org/0day-ci/archive/20231112/202311121240.AN8GbAbe-lkp@intel.com/config)
> compiler: clang version 16.0.4 (https://github.com/llvm/llvm-project.git ae42196bc493ffe877a7e3dff8be32035dea4d07)
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231112/202311121240.AN8GbAbe-lkp@intel.com/reproduce)
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@intel.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202311121240.AN8GbAbe-lkp@intel.com/
> 
> All errors (new ones prefixed by >>):
> 
> >> ld.lld: error: undefined symbol: __muloti4
>    >>> referenced by buffer.c
>    >>>               fs/buffer.o:(bdev_getblk) in archive vmlinux.a
>    >>> referenced by buffer.c
>    >>>               fs/buffer.o:(bdev_getblk) in archive vmlinux.a
> 

What a peculiar compiler.

I assume this fixes?

--- a/fs/buffer.c~buffer-fix-grow_buffers-for-block-size-page_size-fix
+++ a/fs/buffer.c
@@ -1099,7 +1099,7 @@ static bool grow_buffers(struct block_de
 	}
 
 	/* Create a folio with the proper size buffers */
-	return grow_dev_folio(bdev, block, pos / PAGE_SIZE, size, gfp);
+	return grow_dev_folio(bdev, block, pos >> PAGE_SHIFT, size, gfp);
 }
 
 static struct buffer_head *
_