Merge patch series "iomap: allow the file system to submit the writeback bios"

Christoph Hellwig <hch@lst.de> says:

This series contains the iomap prep work to support zoned XFS.

The biggest changes are:

 - an option to reuse the ioend code for direct writes in addition to the
   current use for buffered writeback, which allows the file system to
   track completions on a per-bio basis instead of the current end_io
   callback which operates on the entire I/O.
   Note that it might make sense to split the ioend code from
   buffered-io.c into its own file with this.  Let me know what you think
   of that and I can include it in the next version
 - change of the writeback_ops so that the submit_bio call can be done by
   the file system.  Note that btrfs will also need this eventually when
   it starts using iomap
 - helpers to split ioend to the zone append queue_limits that plug
   into the previous item above.
 - a new ANON_WRITE flags for writes that don't have a block number
   assigned to them at the iomap level, leaving the file system to do
   that work in the submission handler.  Note that btrfs wants something
   similar also for compressed I/O, which should be able to reuse this,
   maybe with minor tweaks.
 - passing private data to a few more helper

The XFS changes to use this will be posted to the xfs list only to not
spam fsdevel too much.

* patches from https://lore.kernel.org/r/20250206064035.2323428-2-hch@lst.de:
  iomap: pass private data to iomap_truncate_page
  iomap: pass private data to iomap_zero_range
  iomap: pass private data to iomap_page_mkwrite
  iomap: add a io_private field to struct iomap_ioend
  iomap: optionally use ioends for direct I/O
  iomap: factor out a iomap_dio_done helper
  iomap: move common ioend code to ioend.c
  iomap: split bios to zone append limits in the submission handlers
  iomap: add a IOMAP_F_ANON_WRITE flag
  iomap: simplify io_flags and io_type in struct iomap_ioend
  iomap: allow the file system to submit the writeback bios

Link: https://lore.kernel.org/r/20250206064035.2323428-2-hch@lst.de
Signed-off-by: Christian Brauner <brauner@kernel.org>