Merge patch series "allow file systems to increase the minimum writeback chunk size v2"

Christoph Hellwig <hch@lst.de> says:

The relatively low minimal writeback size of 4MiB leads means that
written back inodes on rotational media are switched a lot.  Besides
introducing additional seeks, this also can lead to extreme file
fragmentation on zoned devices when a lot of files are cached relative
to the available writeback bandwidth.

Add a superblock field that allows the file system to override the
default size, and set it to the zone size for zoned XFS.

* patches from https://patch.msgid.link/20251017034611.651385-1-hch@lst.de:
  xfs: set s_min_writeback_pages for zoned file systems
  writeback: allow the file system to override MIN_WRITEBACK_PAGES
  writeback: cleanup writeback_chunk_size

Link: https://patch.msgid.link/20251017034611.651385-1-hch@lst.de
Signed-off-by: Christian Brauner <brauner@kernel.org>