On Tue 28-11-23 14:33:44, Nathan Chancellor wrote:
> Hi Stephen (and other maintainers),
>
> On Mon, Nov 27, 2023 at 09:20:01AM +1100, Stephen Rothwell wrote:
> > Hi all,
> >
> > Today's linux-next merge of the vfs-brauner tree got a conflict in:
> >
> > fs/btrfs/super.c
> >
> > between commit:
> >
> > 2f2cfead5107 ("btrfs: remove old mount API code")
> >
> > from the btrfs tree and commit:
> >
> > ead622674df5 ("btrfs: Do not restrict writes to btrfs devices")
> >
> > from the vfs-brauner tree.
> >
> > I fixed it up (the former removed the funtion updated by the latter, but
> > a further fix may be required to implement the intent of the latter?)
>
> Yes, the lack of ead622674df5 appears to cause issues with mounting
> btrfs volumes on at least next-20231128 due to the presence of commit
> 6f861765464f ("fs: Block writes to mounted block devices"). In QEMU, I
> can see:
>
> :: running early hook [udev]
> Warning: /lib/modules/6.7.0-rc3-next-20231128/modules.devname not found - ignoring
> Starting systemd-udevd version 252.5-1-arch
> :: running hook [udev]
> :: Triggering uevents...
> :: running hook [keymap]
> :: Loading keymap...kbd_mode: KDSKBMODE: Inappropriate ioctl for device
> done.
> :: performing fsck on '/dev/vda2'
> :: mounting '/dev/vda2' on real root
> mount: /new_root: wrong fs type, bad option, bad superblock on /dev/vda2, missing codepage or helper program, or other error.
> dmesg(1) may have more information after failed mount system call.
> You are now being dropped into an emergency shell.
> sh: can't access tty; job control turned off
> [rootfs ]#
>
> The following diff allows my VM to boot properly but I am not sure if
> there is a better or more proper fix (I am already out of my element
> heh). If a proper merge solution cannot be found quickly, can
> 6f861765464f be reverted in the meantime so that all my machines with
> btrfs can boot properly? :)
>
> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
> index 99d10a25a579..23db0306b8ef 100644
> --- a/fs/btrfs/super.c
> +++ b/fs/btrfs/super.c
> @@ -299,6 +299,7 @@ static int btrfs_parse_param(struct fs_context *fc,
> case Opt_device: {
> struct btrfs_device *device;
> blk_mode_t mode = sb_open_mode(fc->sb_flags);
> + mode &= ~BLK_OPEN_RESTRICT_WRITES;
>
> mutex_lock(&uuid_mutex);
> device = btrfs_scan_one_device(param->string, mode, false);
> @@ -1801,6 +1802,8 @@ static int btrfs_get_tree_super(struct fs_context *fc)
> blk_mode_t mode = sb_open_mode(fc->sb_flags);
> int ret;
>
> + mode &= ~BLK_OPEN_RESTRICT_WRITES;
> +
> btrfs_ctx_to_info(fs_info, ctx);
> mutex_lock(&uuid_mutex);
This looks like the proper resolution. Basically btrfs needs to strip
BLK_OPEN_RESTRICT_WRITES from the mode provided by sb_open_mode(). Thanks
for writing it!
Honza
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
