Re: [PATCH 1/3] btrfs: zlib: fix and simplify the inline extent decompression

[David Sterba <dsterba@suse.cz>]

On Wed, Jan 10, 2024 at 12:33:17PM +1030, Qu Wenruo wrote:
> 
> 
> On 2024/1/10 12:29, David Sterba wrote:
> > On Tue, Jan 09, 2024 at 11:02:54AM +0800, kernel test robot wrote:
> >> Hi Qu,
> >>
> >> kernel test robot noticed the following build warnings:
> >>
> >> [auto build test WARNING on kdave/for-next]
> >> [also build test WARNING on next-20240108]
> >> [cannot apply to linus/master v6.7]
> >> [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/Qu-Wenruo/btrfs-zlib-fix-and-simplify-the-inline-extent-decompression/20240108-171206
> >> base:   https://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux.git for-next
> >> patch link:    https://lore.kernel.org/r/29b7793e53e1cdd559ad212ee69cec211a3b4db2.1704704328.git.wqu%40suse.com
> >> patch subject: [PATCH 1/3] btrfs: zlib: fix and simplify the inline extent decompression
> >> config: i386-allmodconfig (https://download.01.org/0day-ci/archive/20240109/202401091012.pLm6PcKG-lkp@intel.com/config)
> >> compiler: ClangBuiltLinux clang version 17.0.6 (https://github.com/llvm/llvm-project 6009708b4367171ccdbf4b5905cb6a803753fe18)
> >> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240109/202401091012.pLm6PcKG-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/202401091012.pLm6PcKG-lkp@intel.com/
> >>
> >> All warnings (new ones prefixed by >>):
> >>
> >>>> fs/btrfs/zlib.c:402:15: warning: format specifies type 'unsigned long' but the argument has type 'size_t' (aka 'unsigned int') [-Wformat]
> >>       401 |                 pr_warn_ratelimited("BTRFS: infalte failed, decompressed=%lu expected=%lu\n",
> >>           |                                                                                       ~~~
> >>           |                                                                                       %zu
> >>       402 |                                         to_copy, destlen);
> >>           |                                                  ^~~~~~~
> > 
> > Valid report but I can't reproduce it. Built with clang 17 and
> > explicitly enabled -Wformat. We have additional warnings enabled per
> > directory fs/btrfs/ so we can add -Wformat, I'd like to know what I'm
> > missing, we've had fixups for the size_t printk format so it would make
> > sense to catch it early.
> 
> I guess it's due to the platform? (The report is from 32bit system).

Ah I see, I build on 64bit platform but should the Wformat warning also
point out mismatch there? The size_t type is an alias of unsigned long
so it is not an error but when size_t and %zu don't match could be a
platform-independent error, no? This would save us reports and followup
fixups roundtrips.

> Otherwise it's indeed my bad, for now I don't even have a 32bit VM to 
> verify, thus my LSP doesn't warn me about the format.

Yeah, it could/should though.