allow file systems to increase the minimum writeback chunk size

Christoph Hellwig
2025-10-15T06:27:35Z

Hi all,

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.

Diffstat:
b/fs/fs-writeback.c | 14 +++++---------
b/fs/super.c | 1 +
b/fs/xfs/xfs_zone_alloc.c | 7 +++++--
b/include/linux/fs.h | 1 +
b/include/linux/writeback.h | 5 +++++
fs/fs-writeback.c | 14 +++++---------
6 files changed, 22 insertions(+), 20 deletions(-)