libfuse: add "time_gran" option

This allows the filesystem to specify the time granularity it
supports when the kernel is responsible for updating times
("writeback_cache" option).

4 files changed, 33 insertions, 3 deletions

diff --git a/ChangeLog b/ChangeLog
index fd3acd5..167ca7e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -8,6 +8,10 @@
 	result in EINVAL when mounting the filesystem.  This also needs a
 	fix in the kernel.
 
+	* libfuse: add "time_gran" option.  This allows the filesystem to
+	specify the time granularity it supports when the kernel is
+	responsible for updating times ("writeback_cache" option).
+
 2014-03-26  Miklos Szeredi <miklos@szeredi.hu>
 
 	* Initilaize stat buffer passed to ->getattr() and ->fgetattr() to
diff --git a/include/fuse_common.h b/include/fuse_common.h
index 22d9591..aec4349 100644
--- a/include/fuse_common.h
+++ b/include/fuse_common.h
@@ -190,9 +190,17 @@ struct fuse_conn_info {
 	unsigned congestion_threshold;
 
 	/**
+	 * Time granularity if kernel is responsible for setting times (in nsec)
+	 *
+	 * Should be power of 10.  A zero (default) value is equivalent to
+	 * 1000000000 (1sec).
+	 */
+	unsigned time_gran;
+
+	/**
 	 * For future use.
 	 */
-	unsigned reserved[23];
+	unsigned reserved[22];
 };
 
 struct fuse_session;
diff --git a/include/fuse_kernel.h b/include/fuse_kernel.h
index 7974721..d1b4e2c 100644
--- a/include/fuse_kernel.h
+++ b/include/fuse_kernel.h
@@ -96,6 +96,8 @@
  *
  * 7.23
  *  - add FUSE_WRITEBACK_CACHE
+ *  - add time_gran to fuse_init_out
+ *  - add reserved space to fuse_init_out
  */
 
 #ifndef _LINUX_FUSE_H
@@ -131,7 +133,7 @@
 #define FUSE_KERNEL_VERSION 7
 
 /** Minor version number of this interface */
-#define FUSE_KERNEL_MINOR_VERSION 22
+#define FUSE_KERNEL_MINOR_VERSION 23
 
 /** The node ID of the root inode */
 #define FUSE_ROOT_ID 1
@@ -559,6 +561,9 @@ struct fuse_init_in {
 	uint32_t	flags;
 };
 
+#define FUSE_COMPAT_INIT_OUT_SIZE 8
+#define FUSE_COMPAT_22_INIT_OUT_SIZE 24
+
 struct fuse_init_out {
 	uint32_t	major;
 	uint32_t	minor;
@@ -567,6 +572,8 @@ struct fuse_init_out {
 	uint16_t	max_background;
 	uint16_t	congestion_threshold;
 	uint32_t	max_write;
+	uint32_t	time_gran;
+	uint32_t	unused[9];
 };
 
 #define CUSE_INIT_INFO_MAX 4096
diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c
index 4284535..dc27cb5 100755
--- a/lib/fuse_lowlevel.c
+++ b/lib/fuse_lowlevel.c
@@ -1844,6 +1844,7 @@ static void do_init(fuse_req_t req, fuse_ino_t nodeid, const void *inarg)
 	struct fuse_init_out outarg;
 	struct fuse_ll *f = req->f;
 	size_t bufsize = f->bufsize;
+	size_t outargsize = sizeof(outarg);
 
 	(void) nodeid;
 	if (f->debug) {
@@ -2017,6 +2018,8 @@ static void do_init(fuse_req_t req, fuse_ino_t nodeid, const void *inarg)
 		outarg.max_background = f->conn.max_background;
 		outarg.congestion_threshold = f->conn.congestion_threshold;
 	}
+	if (f->conn.proto_minor >= 23)
+		outarg.time_gran = f->conn.time_gran;
 
 	if (f->debug) {
 		fprintf(stderr, "   INIT: %u.%u\n", outarg.major, outarg.minor);
@@ -2028,9 +2031,15 @@ static void do_init(fuse_req_t req, fuse_ino_t nodeid, const void *inarg)
 			outarg.max_background);
 		fprintf(stderr, "   congestion_threshold=%i\n",
 		        outarg.congestion_threshold);
+		fprintf(stderr, "   time_gran=%u\n",
+			outarg.time_gran);
 	}
+	if (arg->minor < 5)
+		outargsize = FUSE_COMPAT_INIT_OUT_SIZE;
+	else if (arg->minor < 23)
+		outargsize = FUSE_COMPAT_22_INIT_OUT_SIZE;
 
-	send_reply_ok(req, &outarg, arg->minor < 5 ? 8 : sizeof(outarg));
+	send_reply_ok(req, &outarg, outargsize);
 }
 
 static void do_destroy(fuse_req_t req, fuse_ino_t nodeid, const void *inarg)
@@ -2625,6 +2634,7 @@ static const struct fuse_opt fuse_ll_opts[] = {
 	{ "no_async_dio", offsetof(struct fuse_ll, no_async_dio), 1},
 	{ "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 },
 	FUSE_OPT_KEY("max_read=", FUSE_OPT_KEY_DISCARD),
 	FUSE_OPT_KEY("-h", KEY_HELP),
 	FUSE_OPT_KEY("--help", KEY_HELP),
@@ -2660,6 +2670,7 @@ static void fuse_ll_help(void)
 "    -o readdirplus=S         control readdirplus use (yes|no|auto)\n"
 "    -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"
 );
 }