[PATCH RFC 0/6] btrfs: go fs_holder_ops and add shutdown_bdev() callback

[Qu Wenruo <wqu@suse.com>]

This series is relying on another series here:
https://lore.kernel.org/linux-btrfs/cover.1750137547.git.wqu@suse.com/

That above series prepare btrfs to use fs_holder_ops, and the first
patch in this series is exactly making btrfs use that fs_holder_ops.

Then patch 2~4 implements the shutdown ioctl for btrfs.

For now the shutdown ioctl has no proper sync yet.

Patch 5 is the one affecting the generic fs_holder_ops and
super_operations, that we need a shutdown_bdev() variant, which passes
the bdev to the fs and let the fs to determine if they can continue
operation or needs to shutdown.

AKA, the shutdown_bdev() variant is for multi-devices filesystems like
btrfs and bcachefs.

And finally implement the shutdown_bdev() for btrfs, so that eventually
generic/730 can properly pass.

Reason for RFC:

There are still test failures for shutdown group, mostly due to the fact
that btrfs is not implementing the proper flags handling (e.g. currently
the shutdown never sync the fs no matter what).

But I want to get some feedback about the new
super_operations::shutdown_bdev() call back before committing too much.

Qu Wenruo (6):
  btrfs: introduce a new fs state, EMERGENCY_SHUTDOWN
  btrfs: reject file operations if in shutdown state
  btrfs: reject delalloc ranges if the fs is shutdown
  btrfs: implement shutdown ioctl
  fs: introduce a shutdown_bdev super block operation
  btrfs: implement shutdown_bdev super operation callback

 fs/btrfs/file.c            | 25 ++++++++++++++++++++++++-
 fs/btrfs/fs.h              | 18 ++++++++++++++++++
 fs/btrfs/inode.c           | 14 +++++++++++++-
 fs/btrfs/ioctl.c           | 21 +++++++++++++++++++++
 fs/btrfs/messages.c        |  1 +
 fs/btrfs/reflink.c         |  3 +++
 fs/btrfs/super.c           | 34 ++++++++++++++++++++++++++++++++++
 fs/btrfs/volumes.c         |  2 ++
 fs/btrfs/volumes.h         |  5 +++++
 fs/super.c                 |  4 +++-
 include/linux/fs.h         | 10 ++++++++++
 include/uapi/linux/btrfs.h |  9 +++++++++
 12 files changed, 143 insertions(+), 3 deletions(-)

-- 
2.49.0