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

diff --git a/example/passthrough.c b/example/passthrough.c
index 5a0d6d70bac73fed43656f096304a1e778e93be5..30a8ad51ceca9be9e193711dcf79d542ff85e646 100644 (file)
--- a/example/passthrough.c
+++ b/example/passthrough.c
@@ -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;
 }

diff --git a/example/passthrough_fh.c b/example/passthrough_fh.c
index ec426a8b485171d667824b8d2bcf9fc3d59929fa..701d59e2a530fd9e757a6ff95d9a90ca912c5645 100644 (file)
--- a/example/passthrough_fh.c
+++ b/example/passthrough_fh.c
@@ -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;
 }

diff --git a/example/passthrough_hp.cc b/example/passthrough_hp.cc
index 9b17de07dbf0738681a8a0c9d93481f21ed964e2..7f83a7ba6a83cae4518244d7ad5d13a438a2b03c 100644 (file)
--- a/example/passthrough_hp.cc
+++ b/example/passthrough_hp.cc
@@ -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. */

diff --git a/example/passthrough_ll.c b/example/passthrough_ll.c
index b15725f49d097ed0c0d9be9174ae7e63dfa1cfbd..46cc8e0736a69ab5adbaeb5b8db400b4d3878020 100644 (file)
--- 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. */