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| author | yangyun <yangyun50@huawei.com> | 2024-02-23 14:16:05 +0800 |
|---|---|---|
| committer | yangyun <yangyun50@huawei.com> | 2024-02-26 09:32:29 +0800 |
| commit | c45863318889fa6344534537c7ef91a37b3fba32 (patch) | |
| tree | 4d829004b7be50dee6bdb43381efa5a063f8ba14 /example/passthrough_ll.c | |
| parent | fce970c313bf25ba9ae5b6a335e3293736df3d48 (diff) | |
| download | libfuse-c45863318889fa6344534537c7ef91a37b3fba32.tar.gz | |
Enable direct IO for passthrough examples when open has flag O_DIRECT
Shared locks (parallel_direct_writes) cannot be enabled for O_DIRECT, as
O_DIRECT may be set past file open time with fcntl(fd, F_SETFD, ...).
Kernel side fuse has precautions for shared lock direct-IO (direct_io in
libfuse), as it needs an exclusive inode lock when direct and page cache
IO happend at the same time.
In order to enjoy the parallel_direct_writes feature (i.e., get a shared
lock, not exclusive lock) for writes to the same file), direct_io is needed.
The feature direct_io is corresponding to FOPEN_DIRECT_IO in fuse kernel.
FOPEN_DIRECT_IO and O_DIRECT are not entirely the same as described above.
So enable direct_io (i.e., FOPEN_DIRECT_IO in fuse kernel) to enjoy parallel
direct_writes.
Some patches related to FOPEN_DIRECT_IO and O_DIRECT are below:
https://lore.kernel.org/all/753d6823-e984-4730-a126-d66b65ea772c@ddn.com
Diffstat (limited to 'example/passthrough_ll.c')
| -rw-r--r-- | example/passthrough_ll.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/example/passthrough_ll.c b/example/passthrough_ll.c index b15725f..46cc8e0 100644 --- a/example/passthrough_ll.c +++ b/example/passthrough_ll.c @@ -837,6 +837,12 @@ static void lo_open(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi) else if (lo->cache == CACHE_ALWAYS) fi->keep_cache = 1; + /* Enable direct_io when open has flags O_DIRECT to enjoy the feature + parallel_direct_writes (i.e., to get a shared lock, not exclusive lock, + for writes to the same file in the kernel). */ + if (fi->flags & O_DIRECT) + fi->direct_io = 1; + /* parallel_direct_writes feature depends on direct_io features. To make parallel_direct_writes valid, need set fi->direct_io in current function. */ |