fuse: Add support for passthrough read/write

index ebb5e37..5cc5385 100644
@@ -7,6 +7,7 @@
 */
 
 #include "fuse_i.h"
+#include "fuse_passthrough.h"
 
 #include <linux/init.h>
 #include <linux/module.h>

@@ -569,6 +570,8 @@ ssize_t fuse_simple_request(struct fuse_conn *fc, struct fuse_args *args)
 	if (!ret && args->out.argvar) {
 		BUG_ON(args->out.numargs != 1);
 		ret = req->out.args[0].size;
+		if (req->passthrough_filp != NULL)
+			args->out.passthrough_filp = req->passthrough_filp;
 	}
 	fuse_put_request(fc, req);
 

@@ -1934,6 +1937,7 @@ static ssize_t fuse_dev_do_write(struct fuse_dev *fud,
 	err = copy_out_args(cs, &req->out, nbytes);
 	fuse_copy_finish(cs);
 
+	fuse_setup_passthrough(fc, req);
 	spin_lock(&fpq->lock);
 	clear_bit(FR_LOCKED, &req->flags);
 	if (!fpq->connected)

index 712601f..ef34298 100644
@@ -428,6 +428,7 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry,
 	args.out.args[0].value = &outentry;
 	args.out.args[1].size = sizeof(outopen);
 	args.out.args[1].value = &outopen;
+	args.out.passthrough_filp = NULL;
 	err = fuse_simple_request(fc, &args);
 	if (err)
 		goto out_free_ff;

@@ -439,6 +440,8 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry,
 	ff->fh = outopen.fh;
 	ff->nodeid = outentry.nodeid;
 	ff->open_flags = outopen.open_flags;
+	if (args.out.passthrough_filp != NULL)
+		ff->passthrough_filp = args.out.passthrough_filp;
 	inode = fuse_iget(dir->i_sb, outentry.nodeid, outentry.generation,
 			  &outentry.attr, entry_attr_timeout(&outentry), 0);
 	if (!inode) {

index 570ca40..14b0c69 100644
@@ -7,6 +7,7 @@
 */
 
 #include "fuse_i.h"
+#include "fuse_passthrough.h"
 
 #include <linux/pagemap.h>
 #include <linux/slab.h>

@@ -21,8 +22,10 @@
 static const struct file_operations fuse_direct_io_file_operations;
 
 static int fuse_send_open(struct fuse_conn *fc, u64 nodeid, struct file *file,
-			  int opcode, struct fuse_open_out *outargp)
+			  int opcode, struct fuse_open_out *outargp,
+			  struct file **passthrough_filpp)
 {
+	int ret_val;
 	struct fuse_open_in inarg;
 	FUSE_ARGS(args);
 

@@ -38,8 +41,14 @@ static int fuse_send_open(struct fuse_conn *fc, u64 nodeid, struct file *file,
 	args.out.numargs = 1;
 	args.out.args[0].size = sizeof(*outargp);
 	args.out.args[0].value = outargp;
+	args.out.passthrough_filp = NULL;
 
-	return fuse_simple_request(fc, &args);
+	ret_val = fuse_simple_request(fc, &args);
+
+	if (args.out.passthrough_filp != NULL)
+		*passthrough_filpp = args.out.passthrough_filp;
+
+	return ret_val;
 }
 
 struct fuse_file *fuse_file_alloc(struct fuse_conn *fc)

@@ -50,6 +59,7 @@ struct fuse_file *fuse_file_alloc(struct fuse_conn *fc)
 	if (unlikely(!ff))
 		return NULL;
 
+	ff->passthrough_filp = NULL;
 	ff->fc = fc;
 	ff->reserved_req = fuse_request_alloc(0);
 	if (unlikely(!ff->reserved_req)) {

@@ -117,6 +127,7 @@ int fuse_do_open(struct fuse_conn *fc, u64 nodeid, struct file *file,
 		 bool isdir)
 {
 	struct fuse_file *ff;
+	struct file *passthrough_filp = NULL;
 	int opcode = isdir ? FUSE_OPENDIR : FUSE_OPEN;
 
 	ff = fuse_file_alloc(fc);

@@ -129,10 +140,12 @@ int fuse_do_open(struct fuse_conn *fc, u64 nodeid, struct file *file,
 		struct fuse_open_out outarg;
 		int err;
 
-		err = fuse_send_open(fc, nodeid, file, opcode, &outarg);
+		err = fuse_send_open(fc, nodeid, file, opcode, &outarg,
+				     &(passthrough_filp));
 		if (!err) {
 			ff->fh = outarg.fh;
 			ff->open_flags = outarg.open_flags;
+			ff->passthrough_filp = passthrough_filp;
 
 		} else if (err != -ENOSYS || isdir) {
 			fuse_file_free(ff);

@@ -252,6 +265,8 @@ void fuse_release_common(struct file *file, int opcode)
 	if (unlikely(!ff))
 		return;
 
+	fuse_passthrough_release(ff);
+
 	req = ff->reserved_req;
 	fuse_prepare_release(ff, file->f_flags, opcode);
 

@@ -896,8 +911,10 @@ out:
 
 static ssize_t fuse_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
 {
+	ssize_t ret_val;
 	struct inode *inode = iocb->ki_filp->f_mapping->host;
 	struct fuse_conn *fc = get_fuse_conn(inode);
+	struct fuse_file *ff = iocb->ki_filp->private_data;
 
 	/*
 	 * In auto invalidate mode, always update attributes on read.

@@ -912,7 +929,12 @@ static ssize_t fuse_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
 			return err;
 	}
 
-	return generic_file_read_iter(iocb, to);
+	if (ff && ff->passthrough_filp)
+		ret_val = fuse_passthrough_read_iter(iocb, to);
+	else
+		ret_val = generic_file_read_iter(iocb, to);
+
+	return ret_val;
 }
 
 static void fuse_write_fill(struct fuse_req *req, struct fuse_file *ff,

@@ -1144,6 +1166,7 @@ static ssize_t fuse_perform_write(struct file *file,
 static ssize_t fuse_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 {
 	struct file *file = iocb->ki_filp;
+	struct fuse_file *ff = file->private_data;
 	struct address_space *mapping = file->f_mapping;
 	ssize_t written = 0;
 	ssize_t written_buffered = 0;

@@ -1177,8 +1200,14 @@ static ssize_t fuse_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	if (err)
 		goto out;
 
+	if (ff && ff->passthrough_filp) {
+		written = fuse_passthrough_write_iter(iocb, from);
+		goto out;
+	}
+
 	if (iocb->ki_flags & IOCB_DIRECT) {
 		loff_t pos = iocb->ki_pos;
+
 		written = generic_file_direct_write(iocb, from, pos);
 		if (written < 0 || !iov_iter_count(from))
 			goto out;

index 4051131..2f4d986 100644
@@ -157,6 +157,9 @@ struct fuse_file {
 
 	/** Has flock been performed on this file? */
 	bool flock:1;
+
+	/* the read write file */
+	struct file *passthrough_filp;
 };
 
 /** One input argument of a request */

@@ -236,6 +239,7 @@ struct fuse_args {
 		unsigned argvar:1;
 		unsigned numargs;
 		struct fuse_arg args[2];
+		struct file *passthrough_filp;
 	} out;
 };
 

@@ -374,6 +378,9 @@ struct fuse_req {
 
 	/** Request is stolen from fuse_file->reserved_req */
 	struct file *stolen_file;
+
+	/** fuse passthrough file  */
+	struct file *passthrough_filp;
 };
 
 struct fuse_iqueue {

@@ -531,6 +538,9 @@ struct fuse_conn {
 	/** write-back cache policy (default is write-through) */
 	unsigned writeback_cache:1;
 
+	/** passthrough IO. */
+	unsigned passthrough:1;
+
 	/*
 	 * The following bitfields are only for optimization purposes
 	 * and hence races in setting them will not cause malfunction

new file mode 100644
index 0000000..62f12c1
@@ -0,0 +1,31 @@
+/*
+ * Copyright (c) 2015-2016, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#ifndef _FS_FUSE_PASSTHROUGH_H
+#define _FS_FUSE_PASSTHROUGH_H
+
+#include "fuse_i.h"
+
+#include <linux/fuse.h>
+#include <linux/file.h>
+
+void fuse_setup_passthrough(struct fuse_conn *fc, struct fuse_req *req);
+
+ssize_t fuse_passthrough_read_iter(struct kiocb *iocb, struct iov_iter *to);
+
+ssize_t fuse_passthrough_write_iter(struct kiocb *iocb, struct iov_iter *from);
+
+void fuse_passthrough_release(struct fuse_file *ff);
+
+#endif /* _FS_FUSE_PASSTHROUGH_H */

index 2913db2..33ec874 100644
@@ -860,6 +860,7 @@ static void process_init_reply(struct fuse_conn *fc, struct fuse_req *req)
 		fc->conn_error = 1;
 	else {
 		unsigned long ra_pages;
+		struct super_block *sb = fc->sb;
 
 		process_init_limits(fc, arg);
 

@@ -898,6 +899,13 @@ static void process_init_reply(struct fuse_conn *fc, struct fuse_req *req)
 				fc->async_dio = 1;
 			if (arg->flags & FUSE_WRITEBACK_CACHE)
 				fc->writeback_cache = 1;
+			if (arg->flags & FUSE_PASSTHROUGH) {
+				fc->passthrough = 1;
+				/* Prevent further stacking */
+				sb->s_stack_depth = FILESYSTEM_MAX_STACK_DEPTH;
+				pr_info("FUSE: Pass through is enabled [%s : %d]!\n",
+					current->comm, current->pid);
+			}
 			if (arg->time_gran && arg->time_gran <= 1000000000)
 				fc->sb->s_time_gran = arg->time_gran;
 		} else {

126 lines not on this page · raw message

index c9aca04..a08933a 100644
@@ -250,6 +250,7 @@ struct fuse_file_lock {
 #define FUSE_ASYNC_DIO		(1 << 15)
 #define FUSE_WRITEBACK_CACHE	(1 << 16)
 #define FUSE_NO_OPEN_SUPPORT	(1 << 17)
+#define FUSE_PASSTHROUGH	(1 << 18)
 
 /**
  * CUSE INIT request/reply flags

@@ -480,7 +481,7 @@ struct fuse_create_in {
 struct fuse_open_out {
 	uint64_t	fh;
 	uint32_t	open_flags;
-	uint32_t	padding;
+	int32_t         passthrough_fd;
 };
 
 struct fuse_release_in {