[$] Atomic writes for ext4

Building on the discussion in the two previous sessions on untorn (or
atomic) writes, for buffered I/O and for XFS using direct I/O, Ojaswin Mujoo
remotely led a
session on support for the feature on ext4. That took place in the combined storage and
filesystem track at the
2025 Linux Storage, Filesystem, Memory Management, and BPF Summit. Part of
the support for the feature is already in the upstream kernel, with more
coming. But
there are still some challenges that Mujoo wanted to discuss.