This series consolidates DIO writes into a single code path via
fuse_cache_write_iter/generic_file_direct_write. Before
it was only used for O_DIRECT and when writeback cache was not enabled.
For server/daemon dio enforcement (FOPEN_DIRECT_IO) another code
path was used before, but I _think_ that is not needed and
just IOCB_DIRECT needs to be set/enforced.
When writeback-cache was enabled another code path was used, with
a fallback to write-through - for direct IO that should not be
needed either.
So far O_DIRECT through fuse_cache_write_iter also took an exclusive
lock, this should not be needed either, at least when server side
sets FOPEN_PARALLEL_DIRECT_WRITES.
Regarding xfstests, without FOPEN_DIRECT_IO there are no differences
between patched and unpatched. With FOPEN_DIRECT_IO the series
fixes generic/647, which was failing unpatched ("pwrite is broken").
v4:
checkpatch cleanup
Addresses review comments
- Fix shared lock in fuse_cache_write_iter, file_remove_privs()
needs the exclusive lock. In order to know if the exclusive
lock is needed the new exported vfs function file_remove_privs()
is introduced.
- Also fixed for the shared lock is the fallback to buffered writes,
which also needs the exclusive lock.
- Fixed is the accidental turn around of false/true in
fuse_dio_wr_exclusive_lock().
- Added documentation in fuse_write_flags() that the IOCB_DIRECT flag
cannot be trusted.
New optional patches
- "fuse: Use the existing inode fuse_cache_write_iter"
- "[RFC] fuse: No privilege removal when FOPEN_DIRECT_IO is set"
v3:
Addresses review comments
- Rename fuse_direct_write_extending_i_size to io_past_eof
- Change to single line conditions in fuse_dio_wr_exclusive_lock
(also fixes accidental parenthesis).
- Add another patch to rename fuse_direct_io to fuse_send_dio
- Add detailed information into the commit message of the patch
that consolidates IO paths (5/6, previously 4/5) and also
update the subject.
v2:
The entire v1 approach to route DIO writes through fuse_direct_write_iter
was turned around and fuse_direct_write_iter is removed instead and all
DIO writes are now routed through fuse_cache_write_iter
Cc: Hao Xu <howeyxu@xxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Cc: Miklos Szeredi <miklos@xxxxxxxxxx>
Cc: Dharmendra Singh <dsingh@xxxxxxx>
Cc: linux-fsdevel@xxxxxxxxxxxxxxx
Bernd Schubert (10):
fuse: direct IO can use the write-through code path
fuse: Create helper function if DIO write needs exclusive lock
fuse: prepare support for shared lock for DIO writes
fs: Add and export file_needs_remove_privs
fuse: enable shared lock for O_DIRECT / handle privilege drop
fuse: Rename fuse_direct_io
fuse: Remove fuse_direct_write_iter code path / use IOCB_DIRECT
fuse: Remove page flush/invaliation in fuse_direct_io
fuse: Use the existing inode fuse_cache_write_iter
[RFC] fuse: No privilege removal when FOPEN_DIRECT_IO is set
fs/fuse/cuse.c | 5 +-
fs/fuse/dax.c | 2 +-
fs/fuse/file.c | 189 +++++++++++++++++++++++----------------------
fs/fuse/fuse_i.h | 8 +-
fs/inode.c | 8 ++
include/linux/fs.h | 1 +
6 files changed, 113 insertions(+), 100 deletions(-)
--
2.39.2
