libfuse: add readdirplus support in fuse_lowlevel_ops

This patch implements readdirplus support in FUSE usersapce. It adds
a new fuse lowlevel operations fuse_lowleve_ops::readdir_plus,
corespoding mount options and helper functions to maintain buffer.

[From: Eric Wong <normalperson@yhbt.net>]

This makes our terminology consistent with NFS and
our kernel module, as well as reducing user/developer
confusion in the command-line.

Note: I'm keeping "fuse_add_direntry_plus" since that is
less standardized in its use than "readdirplus" for now.

Signed-off-by: Feng Shuo <steve.shuo.feng@gmail.com>

3 files changed, 49 insertions, 1 deletions

diff --git a/lib/fuse_i.h b/lib/fuse_i.h
index 225ff7d..02e7af1 100644
--- a/lib/fuse_i.h
+++ b/lib/fuse_i.h
@@ -73,6 +73,7 @@ struct fuse_ll {
 	int no_splice_read;
 	int auto_inval_data;
 	int no_auto_inval_data;
+	int no_readdirplus;
 	struct fuse_lowlevel_ops op;
 	int got_init;
 	struct cuse_data *cuse_data;
diff --git a/lib/fuse_lowlevel.c b/lib/fuse_lowlevel.c
index 568cf47..feaa076 100644
--- a/lib/fuse_lowlevel.c
+++ b/lib/fuse_lowlevel.c
@@ -339,6 +339,25 @@ static void fill_entry(struct fuse_entry_out *arg,
 	convert_stat(&e->attr, &arg->attr);
 }
 
+size_t fuse_add_direntry_plus(fuse_req_t req, char *buf, size_t bufsize,
+			      const char *name,
+			      const struct fuse_entry_param *e, off_t off)
+{
+	struct fuse_entry_out *argp;
+	size_t entsize;
+
+	(void) req;
+	entsize = FUSE_DIRENT_ALIGN(FUSE_NAME_OFFSET_DIRENTPLUS +
+				    fuse_dirent_size(strlen(name)));
+	if (entsize <= bufsize && buf){
+		argp = (struct fuse_entry_out *)buf;
+		memset(argp, 0, sizeof(*argp));
+		fill_entry(argp, e);
+		fuse_add_dirent(buf + sizeof(*argp), name, &(e->attr), off);
+	}
+	return entsize;
+}
+
 static void fill_open(struct fuse_open_out *arg,
 		      const struct fuse_file_info *f)
 {
@@ -1406,6 +1425,21 @@ static void do_readdir(fuse_req_t req, fuse_ino_t nodeid, const void *inarg)
 		fuse_reply_err(req, ENOSYS);
 }
 
+static void do_readdirplus(fuse_req_t req, fuse_ino_t nodeid, const void *inarg)
+{
+	struct fuse_read_in *arg = (struct fuse_read_in *) inarg;
+	struct fuse_file_info fi;
+
+	memset(&fi, 0, sizeof(fi));
+	fi.fh = arg->fh;
+	fi.fh_old = fi.fh;
+
+	if (req->f->op.readdirplus)
+		req->f->op.readdirplus(req, nodeid, arg->size, arg->offset, &fi);
+	else
+		fuse_reply_err(req, ENOSYS);
+}
+
 static void do_releasedir(fuse_req_t req, fuse_ino_t nodeid, const void *inarg)
 {
 	struct fuse_release_in *arg = (struct fuse_release_in *) inarg;
@@ -1806,6 +1840,8 @@ static void do_init(fuse_req_t req, fuse_ino_t nodeid, const void *inarg)
 			f->conn.capable |= FUSE_CAP_FLOCK_LOCKS;
 		if (arg->flags & FUSE_AUTO_INVAL_DATA)
 			f->conn.capable |= FUSE_CAP_AUTO_INVAL_DATA;
+		if (arg->flags & FUSE_DO_READDIRPLUS)
+			f->conn.capable |= FUSE_CAP_READDIRPLUS;
 	} else {
 		f->conn.async_read = 0;
 		f->conn.max_readahead = 0;
@@ -1838,6 +1874,8 @@ static void do_init(fuse_req_t req, fuse_ino_t nodeid, const void *inarg)
 		f->conn.want |= FUSE_CAP_BIG_WRITES;
 	if (f->auto_inval_data)
 		f->conn.want |= FUSE_CAP_AUTO_INVAL_DATA;
+	if (f->op.readdirplus && !f->no_readdirplus)
+		f->conn.want |= FUSE_CAP_READDIRPLUS;
 
 	if (bufsize < FUSE_MIN_READ_BUFFER) {
 		fprintf(stderr, "fuse: warning: buffer size too small: %zu\n",
@@ -1861,6 +1899,8 @@ static void do_init(fuse_req_t req, fuse_ino_t nodeid, const void *inarg)
 		f->conn.want &= ~FUSE_CAP_SPLICE_MOVE;
 	if (f->no_auto_inval_data)
 		f->conn.want &= ~FUSE_CAP_AUTO_INVAL_DATA;
+	if (f->no_readdirplus)
+		f->conn.want &= ~FUSE_CAP_READDIRPLUS;
 
 	if (f->conn.async_read || (f->conn.want & FUSE_CAP_ASYNC_READ))
 		outarg.flags |= FUSE_ASYNC_READ;
@@ -1878,6 +1918,8 @@ static void do_init(fuse_req_t req, fuse_ino_t nodeid, const void *inarg)
 		outarg.flags |= FUSE_FLOCK_LOCKS;
 	if (f->conn.want & FUSE_CAP_AUTO_INVAL_DATA)
 		outarg.flags |= FUSE_AUTO_INVAL_DATA;
+	if (f->conn.want & FUSE_CAP_READDIRPLUS)
+		outarg.flags |= FUSE_DO_READDIRPLUS;
 	outarg.max_readahead = f->conn.max_readahead;
 	outarg.max_write = f->conn.max_write;
 	if (f->conn.proto_minor >= 13) {
@@ -2294,6 +2336,7 @@ static struct {
 	[FUSE_DESTROY]	   = { do_destroy,     "DESTROY"     },
 	[FUSE_NOTIFY_REPLY] = { (void *) 1,    "NOTIFY_REPLY" },
 	[FUSE_BATCH_FORGET] = { do_batch_forget, "BATCH_FORGET" },
+	[FUSE_READDIRPLUS] = { do_readdirplus,	"READDIRPLUS"},
 	[CUSE_INIT]	   = { cuse_lowlevel_init, "CUSE_INIT"   },
 };
 
@@ -2402,7 +2445,8 @@ static void fuse_ll_process_buf(void *data, const struct fuse_buf *buf,
 		 in->opcode != FUSE_WRITE && in->opcode != FUSE_FSYNC &&
 		 in->opcode != FUSE_RELEASE && in->opcode != FUSE_READDIR &&
 		 in->opcode != FUSE_FSYNCDIR && in->opcode != FUSE_RELEASEDIR &&
-		 in->opcode != FUSE_NOTIFY_REPLY)
+		 in->opcode != FUSE_NOTIFY_REPLY &&
+		 in->opcode != FUSE_READDIRPLUS)
 		goto reply_err;
 
 	err = ENOSYS;
@@ -2501,6 +2545,7 @@ static const struct fuse_opt fuse_ll_opts[] = {
 	{ "no_splice_read", offsetof(struct fuse_ll, no_splice_read), 1},
 	{ "auto_inval_data", offsetof(struct fuse_ll, auto_inval_data), 1},
 	{ "no_auto_inval_data", offsetof(struct fuse_ll, no_auto_inval_data), 1},
+	{ "no_readdirplus", offsetof(struct fuse_ll, no_readdirplus), 1},
 	FUSE_OPT_KEY("max_read=", FUSE_OPT_KEY_DISCARD),
 	FUSE_OPT_KEY("-h", KEY_HELP),
 	FUSE_OPT_KEY("--help", KEY_HELP),
@@ -2533,6 +2578,7 @@ static void fuse_ll_help(void)
 "    -o [no_]splice_move    move data while splicing to the fuse device\n"
 "    -o [no_]splice_read    use splice to read from the fuse device\n"
 "    -o [no_]auto_inval_data  use automatic kernel cache invalidation logic\n"
+"    -o [no_]readdirplus   use readdirplus if possible.\n"
 );
 }
 
diff --git a/lib/fuse_versionscript b/lib/fuse_versionscript
index ea2a1c8..ad5a940 100644
--- a/lib/fuse_versionscript
+++ b/lib/fuse_versionscript
@@ -51,6 +51,7 @@ FUSE_3.0 {
 		fuse_reply_statfs;
 		fuse_set_signal_handlers;
 		fuse_add_direntry;
+		fuse_add_direntry_plus;
 		fuse_chan_new;
 		fuse_chan_recv;
 		fuse_daemonize;