Re: [GIT PULL] Btrfs updates for 6.3

[Ammar Faizi]

On 2/21/23 4:02 AM, Linus Torvalds wrote:
> On Mon, Feb 20, 2023 at 11:26 AM David Sterba <dsterba@xxxxxxxx> wrote:
> > Other:
> >
> > - locally enable -Wmaybe-uninitialized after fixing all warnings
>
> I've pulled this, but I strongly suspect this change will get reverted.
>
> I bet neither you nor linux-next is testing even _remotely_ a big
> chunk of the different compiler versions that are out there, and the
> reason flags like '-Wmaybe-uninitialized' get undone is because some
> random compiler version on some random config and target archiecture
> gives completely nonsensical warnings for odd reasons.
>
> But hey, maybe the btrfs code is special.

Maybe it's too late for 6.3. So please fix this in 6.4 and backport it to
6.3 stable. If someone fixes it, kindly add:

Reported-by: Memet <zxce3@xxxxxxxxxxx>

Compiling with GCC 9.4:

gcc (Ubuntu 9.4.0-1ubuntu1~20.04.1) 9.4.0
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Linux version 6.3-rc7:

  CC [M]  fs/btrfs/volumes.o
fs/btrfs/volumes.c: In function ‘btrfs_init_new_device’:
fs/btrfs/volumes.c:2524:2: error: ‘seed_devices’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
 2524 |  list_add(&seed_devices->seed_list, &fs_devices->seed_list);
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
fs/btrfs/volumes.c:2621:27: note: ‘seed_devices’ was declared here
 2621 |  struct btrfs_fs_devices *seed_devices;
      |                           ^~~~~~~~~~~~
cc1: all warnings being treated as errors
make[7]: *** [scripts/Makefile.build:252: fs/btrfs/volumes.o] Error 1
make[6]: *** [scripts/Makefile.build:494: fs/btrfs] Error 2
make[5]: *** [scripts/Makefile.build:494: fs] Error 2
make[4]: *** [Makefile:2025: .] Error 2
make[3]: *** [Makefile:357: __build_one_by_one] Error 2
make[2]: *** [debian/rules:8: build-arch] Error 2
dpkg-buildpackage: error: debian/rules binary subprocess returned exit status 2
make[1]: *** [scripts/Makefile.package:120: bindeb-pkg] Error 2
make: *** [Makefile:1656: bindeb-pkg] Error 2


fs/btrfs/send.c: In function ‘get_cur_inode_state’:
fs/btrfs/send.c:1909:13: error: ‘right_gen’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
 1909 |   } else if (right_gen == gen) {
      |             ^

--
Ammar Faizi