Re: [PATCH] btrfs: initialize location to fix -Wmaybe-uninitialized in btrfs_lookup_dentry()

[David Sterba <dsterba@suse.cz>]

On Tue, Jul 30, 2024 at 07:04:36AM +0930, Qu Wenruo wrote:
> 
> 
> 在 2024/7/30 05:36, David Sterba 写道:
> > Some arch + compiler combinations report a potentially unused variable
> > location in btrfs_lookup_dentry(). This is a false alert as the variable
> > is passed by value and always valid or there's an error. The compilers
> > cannot probably reason about that although btrfs_inode_by_name() is in
> > the same file.
> >
> >     >  + /kisskb/src/fs/btrfs/inode.c: error: 'location.objectid' may be used
> >     +uninitialized in this function [-Werror=maybe-uninitialized]:  => 5603:9
> >     >  + /kisskb/src/fs/btrfs/inode.c: error: 'location.type' may be used
> >     +uninitialized in this function [-Werror=maybe-uninitialized]:  => 5674:5
> >
> >     m68k-gcc8/m68k-allmodconfig
> >     mips-gcc8/mips-allmodconfig
> >     powerpc-gcc5/powerpc-all{mod,yes}config
> >     powerpc-gcc5/ppc64_defconfig
> >
> > Initialize it to zero, this should fix the warnings and won't change the
> > behaviour as btrfs_inode_by_name() accepts only a root or inode item
> > types, otherwise returns an error.
> >
> > Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
> > Link: https://lore.kernel.org/linux-btrfs/bd4e9928-17b3-9257-8ba7-6b7f9bbb639a@linux-m68k.org/
> > Signed-off-by: David Sterba <dsterba@suse.com>
> 
> Reviewed-by: Qu Wenruo <wqu@suse.com>
> 
> Although I hate to update our code for bad compilers, I guess it's
> unavoidable anyway.

Yeah, but the number of such fixups is bearable, we have added like one
per release.