[PATCH v7 00/15] f2fs: support & optimize large folios for writable files

[Nanzhe Zhao]

From: Nanzhe Zhao <zhaonanzhe@xxxxxxxxxx>

This series supports large folios for most readable/writable files
in buffered I/O paths, including normal files, block-layer encrypted
files, and atomic files except for inline-data files, compressed files,
and quota files.

It also extends f2fs_folio_state to coexist with f2fs page-private
flags and to handle large folio write path and partial truncate of
large folios correctly.  A valid large folio always carries a
f2fs_folio_state at its folio->private in the current implementation.

Benchmark details can be found in the RFC v2 cover letter:
https://lore.kernel.org/r/20260622160830.324455-1-zhaonanzhe@xxxxxxxxxx

Changes in v7:
- 01/15: realloc the f2fs_folio_state in f2fs_get_lock_data_folio() if
  it was released while the folio was unlocked.
- 04/15: on an atomic buffered write repeat if folio was unlocked, check the 
COW block before reserving it again, so inc_atomic_write_cnt() is not called twice.
- 08/15: clear PAGE_PRIVATE_GCING if large folio has no dirty sub pages
 when f2fs_trylock_op() fails before any write is submitted in f2fs_do_write_data_page().

No other functional changes.

Changes in v6:
- Rebased onto the f2fs dev branch (fd106ada4dee).
- v5 12/16 ("f2fs: wait for folio writeback before ffs_detach_free")
  is dropped, because the lkp warning reported by [1] was caused by a
  write_pages_pending leak on the GC truncate path.

- Improve large-folio support in the f2fs_do_write_data_page() path used
  by GC:
  - 05/15: use __folio_start_writeback(folio, folio_test_dirty(folio))
    in both the IPU and OPU paths, so a single-subpage GC write does not
    clear PAGECACHE_TAG_TOWRITE while other subpages are still dirty [3].
  - 05/15: add f2fs_ffs_put_write_pending() as the common writeback
    completion helper; do_write_block() only ends writeback for order-0
    folios.
  - 08/15: move the write_pages_pending increment from move_data_page()
    into f2fs_do_write_data_page(), take it only after
    __folio_start_writeback(), and drop it on every error path.
    move_data_page() no longer adjusts write_pages_pending or clears
    gcing on error [1].

- 02/15: compute bio_offset/bio_len against the folio actually added to
  the bio [5].

- 05/15, 06/15: fix the order-0 dirty accounting leak in the cp_error
  path [2].

- 10/15: allocate ffs before f2fs_truncate_read_extent() [4].

- 11/15: move the existing truncated-page handling into
  f2fs_clear_truncated_page_state() and reuse it for the subpage-aware
  large-folio writeback path, including the -ENOENT/NULL_ADDR case [2].

Link to v5: [6]

Many thanks to Chao, Daeho and Jaegeuk for the reviews, and to the
kernel test robot for the report.

[1] https://lore.kernel.org/oe-lkp/202610081027.b13dcf10-lkp@xxxxxxxxx
[2] https://lore.kernel.org/r/6be679d1-d8ab-41b3-9975-1f1bcd552579@xxxxxxxxxx
[3] https://lore.kernel.org/r/fc101bc7-6ece-4a30-9e19-9b32376489a8@xxxxxxxxxx
[4] https://lore.kernel.org/r/36220ef3-5b00-4aa1-ad11-60b10857a886@xxxxxxxxxx
[5] https://lore.kernel.org/r/atA8dsZ35E6wTMD6@xxxxxxxxxx
[6] https://lore.kernel.org/r/20261014064445.2835813-1-zhaonanzhe@xxxxxxxxxx/







Nanzhe Zhao (15):
  f2fs: extend folio state for large folio write path
  f2fs: carry subpage offset and count in write IO
  f2fs: support regular file buffered writes on large folios
  f2fs: support atomic file large folios buffered write
  f2fs: support large folio writeback
  f2fs: account large folio dirty data at block granularity
  f2fs: prepare mmap write faults for large folios
  f2fs: make GC migration large-folio aware
  f2fs: optimize small block size large folio read
  f2fs: support partial uptodate large folio read
  f2fs: handle partial truncate of large folio dirty subpages
  f2fs: fix zeroing paths for large folios
  f2fs: handle block cloning within the same large folio
  f2fs: allow large folio support to writeable files
  f2fs: make compressed files compatible with large folio

 Documentation/filesystems/f2fs.rst |   10 +
 fs/f2fs/checkpoint.c               |   40 +-
 fs/f2fs/compress.c                 |    7 +-
 fs/f2fs/data.c                     | 1521 +++++++++++++++++++++++++---
 fs/f2fs/dir.c                      |    2 +-
 fs/f2fs/f2fs.h                     |  170 +++-
 fs/f2fs/file.c                     |  226 +++--
 fs/f2fs/gc.c                       |   32 +-
 fs/f2fs/inline.c                   |    9 +-
 fs/f2fs/inode.c                    |    4 +-
 fs/f2fs/namei.c                    |    1 +
 fs/f2fs/node.c                     |    2 +-
 fs/f2fs/segment.c                  |   13 +-
 13 files changed, 1774 insertions(+), 263 deletions(-)

-- 
2.43.0