[PATCH v3 00/12] fuse: support large folios

[Joanne Koong <joannelkoong@gmail.com>]

This patchset adds support for folios larger than one page size in FUSE.

This patchset is rebased on top of the (unmerged) patchset that removes temp
folios in writeback [1]. This patchset was tested by running it through fstests
on passthrough_hp.

Please note that writes are still effectively one page size. Larger writes can
be enabled by setting the order on the fgp flag passed in to __filemap_get_folio()
but benchmarks show this significantly degrades performance. More investigation
needs to be done into this. As such, buffered writes will be optimized in a
future patchset.

Benchmarks show roughly a ~45% improvement in read throughput.

Benchmark setup:

-- Set up server --
 ./libfuse/build/example/passthrough_hp --bypass-rw=1 ~/libfuse
~/mounts/fuse/ --nopassthrough
(using libfuse patched with https://github.com/libfuse/libfuse/pull/807)

-- Run fio --
 fio --name=read --ioengine=sync --rw=read --bs=1M --size=1G
--numjobs=2 --ramp_time=30 --group_reporting=1
--directory=mounts/fuse/

Machine 1:
    No large folios:     ~4400 MiB/s
    Large folios:        ~7100 MiB/s

Machine 2:
    No large folios:     ~3700 MiB/s
    Large folios:        ~6400 MiB/s


[1] https://lore.kernel.org/linux-fsdevel/20241122232359.429647-1-joannelkoong@gmail.com/

Changelog:
v2: https://lore.kernel.org/linux-fsdevel/20241125220537.3663725-1-joannelkoong@gmail.com/
v2 -> v3:
* Fix direct io parsing to check each extracted page instead of assuming all
  pages in a large folio will be used (Matthew)

v1: https://lore.kernel.org/linux-fsdevel/20241109001258.2216604-1-joannelkoong@gmail.com/
v1 -> v2:
* Change naming from "non-writeback write" to "writethrough write"
* Fix deadlock for writethrough writes by calling fault_in_iov_iter_readable()
* first
  before __filemap_get_folio() (Josef)
* For readahead, retain original folio_size() for descs.length (Josef)
* Use folio_zero_range() api in fuse_copy_folio() (Josef)
* Add Josef's reviewed-bys

Joanne Koong (12):
  fuse: support copying large folios
  fuse: support large folios for retrieves
  fuse: refactor fuse_fill_write_pages()
  fuse: support large folios for writethrough writes
  fuse: support large folios for folio reads
  fuse: support large folios for symlinks
  fuse: support large folios for stores
  fuse: support large folios for queued writes
  fuse: support large folios for readahead
  fuse: optimize direct io large folios processing
  fuse: support large folios for writeback
  fuse: enable large folios

 fs/fuse/dev.c  | 128 ++++++++++++++++++++++---------------------
 fs/fuse/dir.c  |   8 +--
 fs/fuse/file.c | 144 +++++++++++++++++++++++++++++++++----------------
 3 files changed, 166 insertions(+), 114 deletions(-)

-- 
2.43.5