[GIT PULL 04/17 for v6.19] vfs writeback

[Christian Brauner]

Hey Linus,

/* Summary */
This contains writeback changes for this cycle:

Features

- Allow file systems to increase the minimum writeback chunk size. The
  relatively low minimal writeback size of 4MiB 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. This adds a superblock field that allows the file
  system to override the default size, and sets it to the zone size for
  zoned XFS.

- Add logging for slow writeback when it exceeds sysctl_hung_task_timeout_secs.
  This helps identify tasks waiting for a long time and pinpoint potential
  issues. Recording the starting jiffies is also useful when debugging a
  crashed vmcore.

- Wake up waiting tasks when finishing the writeback of a chunk.

Cleanups

- filemap_* writeback interface cleanups. Adding filemap_fdatawrite_wbc
  ended up being a mistake, as all but the original btrfs caller should
  be using better high level interfaces instead. This series removes all
  these low-level interfaces, switches btrfs to a more specific interface,
  and cleans up other too low-level interfaces. With this the
  writeback_control that is passed to the writeback code is only
  initialized in three places.

- Remove __filemap_fdatawrite, __filemap_fdatawrite_range, and
  filemap_fdatawrite_wbc

- Add filemap_flush_nr helper for btrfs

- Push struct writeback_control into start_delalloc_inodes in btrfs

- Rename filemap_fdatawrite_range_kick to filemap_flush_range

- Stop opencoding filemap_fdatawrite_range in 9p, ocfs2, and mm

- Make wbc_to_tag() inline and use it in fs.

/* Testing */

gcc (Debian 14.2.0-19) 14.2.0
Debian clang version 19.1.7 (3+b1)

No build failures or warnings were observed.

/* Conflicts */

Merge conflicts with mainline
=============================

diff --cc include/linux/writeback.h
index 102071ffedcb,2a81816f7507..000000000000
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@@ -189,6 -189,20 +189,13 @@@ void wakeup_flusher_threads_bdi(struct
  void inode_wait_for_writeback(struct inode *inode);
  void inode_io_list_del(struct inode *inode);

 -/* writeback.h requires fs.h; it, too, is not included from here. */
 -static inline void wait_on_inode(struct inode *inode)
 -{
 -      wait_var_event(inode_state_wait_address(inode, __I_NEW),
 -                     !(READ_ONCE(inode->i_state) & I_NEW));
 -}
 -
+ static inline xa_mark_t wbc_to_tag(struct writeback_control *wbc)
+ {
+       if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
+               return PAGECACHE_TAG_TOWRITE;
+       return PAGECACHE_TAG_DIRTY;
+ }
+
  #ifdef CONFIG_CGROUP_WRITEBACK

  #include <linux/cgroup.h>

Merge conflicts with other trees
================================

The following changes since commit 3a8660878839faadb4f1a6dd72c3179c1df56787:

  Linux 6.18-rc1 (2025-10-12 13:42:36 -0700)

are available in the Git repository at:

  git@xxxxxxxxxxxxxxxxxxx:pub/scm/linux/kernel/git/vfs/vfs tags/vfs-6.19-rc1.writeback

for you to fetch changes up to 4952f35f0545f3b53dab8d5fd727c4827c2a2778:

  fs: Make wbc_to_tag() inline and use it in fs. (2025-10-29 23:33:48 +0100)

Please consider pulling these changes from the signed vfs-6.19-rc1.writeback tag.

Thanks!
Christian

----------------------------------------------------------------
vfs-6.19-rc1.writeback

----------------------------------------------------------------
Christian Brauner (2):
      Merge patch series "filemap_* writeback interface cleanups v2"
      Merge patch series "allow file systems to increase the minimum writeback chunk size v2"

Christoph Hellwig (13):
      mm: don't opencode filemap_fdatawrite_range in filemap_invalidate_inode
      9p: don't opencode filemap_fdatawrite_range in v9fs_mmap_vm_close
      ocfs2: don't opencode filemap_fdatawrite_range in ocfs2_journal_submit_inode_data_buffers
      btrfs: use the local tmp_inode variable in start_delalloc_inodes
      btrfs: push struct writeback_control into start_delalloc_inodes
      mm,btrfs: add a filemap_flush_nr helper
      mm: remove __filemap_fdatawrite
      mm: remove filemap_fdatawrite_wbc
      mm: remove __filemap_fdatawrite_range
      mm: rename filemap_fdatawrite_range_kick to filemap_flush_range
      writeback: cleanup writeback_chunk_size
      writeback: allow the file system to override MIN_WRITEBACK_PAGES
      xfs: set s_min_writeback_pages for zoned file systems

Julian Sun (3):
      writeback: Wake up waiting tasks when finishing the writeback of a chunk.
      writeback: Add logging for slow writeback (exceeds sysctl_hung_task_timeout_secs)
      fs: Make wbc_to_tag() inline and use it in fs.

 fs/9p/vfs_file.c                 |  17 ++----
 fs/btrfs/extent_io.c             |   5 +-
 fs/btrfs/inode.c                 |  46 +++++------------
 fs/ceph/addr.c                   |   6 +--
 fs/ext4/inode.c                  |   5 +-
 fs/f2fs/data.c                   |   5 +-
 fs/fs-writeback.c                |  55 ++++++++++++--------
 fs/gfs2/aops.c                   |   5 +-
 fs/ocfs2/journal.c               |  11 +---
 fs/super.c                       |   1 +
 fs/sync.c                        |  10 ++--
 fs/xfs/xfs_zone_alloc.c          |  28 +++++++++-
 include/linux/backing-dev-defs.h |   2 +
 include/linux/fs.h               |   7 +--
 include/linux/pagemap.h          |   5 +-
 include/linux/writeback.h        |  12 +++++
 mm/fadvise.c                     |   3 +-
 mm/filemap.c                     | 109 ++++++++++++++++-----------------------
 mm/page-writeback.c              |   6 ---
 19 files changed, 154 insertions(+), 184 deletions(-)