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Enable direct IO for passthrough examples when open has flag O_DIRECT

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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
This commit is contained in:
yangyun 2024-02-23 14:16:05 +08:00
parent fce970c313
commit c458633188
4 changed files with 28 additions and 0 deletions
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8
example/passthrough.c
View File

@ -303,6 +303,14 @@ static int xmp_open(const char *path, struct fuse_file_info *fi)
if (res == -1)
return -errno;
/* 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). */
if (fi->flags & O_DIRECT) {
fi->direct_io = 1;
fi->parallel_direct_writes = 1;
}
fi->fh = res;
return 0;
}

8
example/passthrough_fh.c
View File

@ -384,6 +384,14 @@ static int xmp_open(const char *path, struct fuse_file_info *fi)
if (fd == -1)
return -errno;
/* 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). */
if (fi->flags & O_DIRECT) {
fi->direct_io = 1;
fi->parallel_direct_writes = 1;
}
fi->fh = fd;
return 0;
}

6
example/passthrough_hp.cc
View File

@ -905,6 +905,12 @@ static void sfs_open(fuse_req_t req, fuse_ino_t ino, fuse_file_info *fi) {
if (fs.direct_io)
fi->direct_io = 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). */
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. */

6
example/passthrough_ll.c
View File

@ -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. */