libfuse: add "clone_fd" optionclone_fd

This creates a separate device file descriptor for each processing thread,
which might improve performance.

5 files changed, 63 insertions, 2 deletions

diff --git a/ChangeLog b/ChangeLog
index 8a65763..4450ca5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -4,6 +4,10 @@
 	fuse_chan_get(), fuse_chan_put().  Removed function:
 	fuse_chan_destroy().
 
+	* libfuse: add "clone_fd" option.  This creates a separate device
+	file descriptor for each processing thread, which might improve
+	performance.
+
 2015-04-23  Miklos Szeredi <miklos@szeredi.hu>
 
 	* libfuse: add FUSE_CAP_NO_OPEN_SUPPORT flag to ->init()
diff --git a/include/fuse_kernel.h b/include/fuse_kernel.h
index 25084a0..c9aca04 100644
--- a/include/fuse_kernel.h
+++ b/include/fuse_kernel.h
@@ -755,4 +755,7 @@ struct fuse_notify_retrieve_in {
 	uint64_t	dummy4;
 };
 
+/* Device ioctls: */
+#define FUSE_DEV_IOC_CLONE	_IOR(229, 0, uint32_t)
+
 #endif /* _LINUX_FUSE_H */
diff --git a/lib/fuse_i.h b/lib/fuse_i.h
index 16adc69..62af9f2 100644
--- a/lib/fuse_i.h
+++ b/lib/fuse_i.h
@@ -80,6 +80,7 @@ struct fuse_ll {
 	int no_async_dio;
 	int writeback_cache;
 	int no_writeback_cache;
+	int clone_fd;
 	struct fuse_lowlevel_ops op;
 	int got_init;
 	struct cuse_data *cuse_data;
diff --git a/lib/fuse_loop_mt.c b/lib/fuse_loop_mt.c
index 8f4dceb..6d7f051 100755
--- a/lib/fuse_loop_mt.c
+++ b/lib/fuse_loop_mt.c
@@ -20,6 +20,7 @@
 #include <semaphore.h>
 #include <errno.h>
 #include <sys/time.h>
+#include <sys/ioctl.h>
 
 /* Environment var controlling the thread stack size */
 #define ENVNAME_THREAD_STACK "FUSE_THREAD_STACK"
@@ -30,6 +31,7 @@ struct fuse_worker {
 	pthread_t thread_id;
 	size_t bufsize;
 	struct fuse_buf fbuf;
+	struct fuse_chan *ch;
 	struct fuse_mt *mt;
 };
 
@@ -74,7 +76,7 @@ static void *fuse_do_work(void *data)
 		int res;
 
 		pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);
-		res = fuse_session_receive_buf(mt->se, &w->fbuf, mt->prevch);
+		res = fuse_session_receive_buf(mt->se, &w->fbuf, w->ch);
 		pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, NULL);
 		if (res == -EINTR)
 			continue;
@@ -110,7 +112,7 @@ static void *fuse_do_work(void *data)
 			fuse_loop_start_thread(mt);
 		pthread_mutex_unlock(&mt->lock);
 
-		fuse_session_process_buf(mt->se, &w->fbuf, mt->prevch);
+		fuse_session_process_buf(mt->se, &w->fbuf, w->ch);
 
 		pthread_mutex_lock(&mt->lock);
 		if (!isforget)
@@ -127,6 +129,7 @@ static void *fuse_do_work(void *data)
 
 			pthread_detach(w->thread_id);
 			free(w->fbuf.mem);
+			fuse_chan_put(w->ch);
 			free(w);
 			return NULL;
 		}
@@ -171,9 +174,46 @@ int fuse_start_thread(pthread_t *thread_id, void *(*func)(void *), void *arg)
 	return 0;
 }
 
+static struct fuse_chan *fuse_clone_chan(struct fuse_mt *mt)
+{
+	int res;
+	int clonefd;
+	uint32_t masterfd;
+	struct fuse_chan *newch;
+	const char *devname = "/dev/fuse";
+
+#ifndef O_CLOEXEC
+#define O_CLOEXEC 0
+#endif
+	clonefd = open(devname, O_RDWR | O_CLOEXEC);
+	if (clonefd == -1) {
+		fprintf(stderr, "fuse: failed to open %s: %s\n", devname,
+			strerror(errno));
+		return NULL;
+	}
+	fcntl(clonefd, F_SETFD, FD_CLOEXEC);
+
+	masterfd = fuse_chan_fd(mt->prevch);
+	res = ioctl(clonefd, FUSE_DEV_IOC_CLONE, &masterfd);
+	if (res == -1) {
+		fprintf(stderr, "fuse: failed to clone device fd: %s\n",
+			strerror(errno));
+		close(clonefd);
+		mt->se->f->clone_fd = 0;
+
+		return fuse_chan_get(mt->prevch);
+	}
+	newch = fuse_chan_new(clonefd);
+	if (newch == NULL)
+		close(clonefd);
+
+	return newch;
+}
+
 static int fuse_loop_start_thread(struct fuse_mt *mt)
 {
 	int res;
+
 	struct fuse_worker *w = malloc(sizeof(struct fuse_worker));
 	if (!w) {
 		fprintf(stderr, "fuse: failed to allocate worker structure\n");
@@ -183,8 +223,18 @@ static int fuse_loop_start_thread(struct fuse_mt *mt)
 	w->fbuf.mem = NULL;
 	w->mt = mt;
 
+
+	if (mt->se->f->clone_fd) {
+		w->ch = fuse_clone_chan(mt);
+		if (!w->ch)
+			return -1;
+	} else {
+		w->ch = fuse_chan_get(mt->prevch);
+	}
+
 	res = fuse_start_thread(&w->thread_id, fuse_do_work, w);
 	if (res == -1) {
+		fuse_chan_put(w->ch);
 		free(w);
 		return -1;
 	}
@@ -202,6 +252,7 @@ static void fuse_join_worker(struct fuse_mt *mt, struct fuse_worker *w)
 	list_del_worker(w);
 	pthread_mutex_unlock(&mt->lock);
 	free(w->fbuf.mem);
+	fuse_chan_put(w->ch);
 	free(w);
 }
 
diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c
index 8433e0a..05103c0 100755
--- a/lib/fuse_lowlevel.c
+++ b/lib/fuse_lowlevel.c
@@ -2657,6 +2657,7 @@ static const struct fuse_opt fuse_ll_opts[] = {
 	{ "writeback_cache", offsetof(struct fuse_ll, writeback_cache), 1},
 	{ "no_writeback_cache", offsetof(struct fuse_ll, no_writeback_cache), 1},
 	{ "time_gran=%u", offsetof(struct fuse_ll, conn.time_gran), 0 },
+	{ "clone_fd", offsetof(struct fuse_ll, clone_fd), 1 },
 	FUSE_OPT_KEY("max_read=", FUSE_OPT_KEY_DISCARD),
 	FUSE_OPT_KEY("-h", KEY_HELP),
 	FUSE_OPT_KEY("--help", KEY_HELP),
@@ -2693,6 +2694,7 @@ static void fuse_ll_help(void)
 "    -o [no_]async_dio        asynchronous direct I/O\n"
 "    -o [no_]writeback_cache  asynchronous, buffered writes\n"
 "    -o time_gran=N           time granularity in nsec\n"
+"    -o clone_fd              clone fuse device file descriptors\n"
 );
 }