Merge tag 'bcachefs-2024-01-01' of https://evilpiepirate.org/git/bcachefs

Pull bcachefs from Kent Overstreet:
 "More bcachefs bugfixes for 6.7, and forwards compatibility work:

   - fix for a nasty extents + snapshot interaction, reported when
     reflink of a snapshotted file wouldn't complete but turned out to
     be a more general bug

   - fix for an invalid free in dio write path when iov vector was
     longer than our inline vector

   - fix for a buffer overflow in the nocow write path -
     BCH_REPLICAS_MAX doesn't actually limit the number of pointers in
     an extent when cached pointers are included

   - RO snapshots are actually RO now

   - And, a new superblock section to avoid future breakage when the
     disk space acounting rewrite rolls out: the new superblock section
     describes versions that need work to downgrade, where the work
     required is a list of recovery passes and errors to silently fix"

* tag 'bcachefs-2024-01-01' of https://evilpiepirate.org/git/bcachefs:
  bcachefs: make RO snapshots actually RO
  bcachefs: bch_sb_field_downgrade
  bcachefs: bch_sb.recovery_passes_required
  bcachefs: Add persistent identifiers for recovery passes
  bcachefs: prt_bitflags_vector()
  bcachefs: move BCH_SB_ERRS() to sb-errors_types.h
  bcachefs: fix buffer overflow in nocow write path
  bcachefs: DARRAY_PREALLOCATED()
  bcachefs: Switch darray to kvmalloc()
  bcachefs: Factor out darray resize slowpath
  bcachefs: fix setting version_upgrade_complete
  bcachefs: fix invalid free in dio write path
  bcachefs: Fix extents iteration + snapshots interaction