fs/fuse/passthrough.c

Source file repositories/reference/linux-study-clean/fs/fuse/passthrough.c

File Facts

System
Linux kernel
Corpus path
fs/fuse/passthrough.c
Extension
.c
Size
4916 bytes
Lines
198
Domain
Core OS
Bucket
VFS And Filesystem Core
Inferred role
Core OS: implementation source
Status
source implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0
/*
 * FUSE passthrough to backing file.
 *
 * Copyright (c) 2023 CTERA Networks.
 */

#include "fuse_i.h"

#include <linux/file.h>
#include <linux/backing-file.h>
#include <linux/splice.h>

static void fuse_file_accessed(struct file *file)
{
	struct inode *inode = file_inode(file);

	fuse_invalidate_atime(inode);
}

static void fuse_passthrough_end_write(struct kiocb *iocb, ssize_t ret)
{
	struct inode *inode = file_inode(iocb->ki_filp);

	fuse_write_update_attr(inode, iocb->ki_pos, ret);
}

ssize_t fuse_passthrough_read_iter(struct kiocb *iocb, struct iov_iter *iter)
{
	struct file *file = iocb->ki_filp;
	struct fuse_file *ff = file->private_data;
	struct file *backing_file = fuse_file_passthrough(ff);
	size_t count = iov_iter_count(iter);
	ssize_t ret;
	struct backing_file_ctx ctx = {
		.cred = ff->cred,
		.accessed = fuse_file_accessed,
	};


	pr_debug("%s: backing_file=0x%p, pos=%lld, len=%zu\n", __func__,
		 backing_file, iocb->ki_pos, count);

	if (!count)
		return 0;

	ret = backing_file_read_iter(backing_file, iter, iocb, iocb->ki_flags,
				     &ctx);

	return ret;
}

ssize_t fuse_passthrough_write_iter(struct kiocb *iocb,
				    struct iov_iter *iter)
{
	struct file *file = iocb->ki_filp;
	struct inode *inode = file_inode(file);
	struct fuse_file *ff = file->private_data;
	struct file *backing_file = fuse_file_passthrough(ff);
	size_t count = iov_iter_count(iter);
	ssize_t ret;
	struct backing_file_ctx ctx = {
		.cred = ff->cred,
		.end_write = fuse_passthrough_end_write,
	};

	pr_debug("%s: backing_file=0x%p, pos=%lld, len=%zu\n", __func__,
		 backing_file, iocb->ki_pos, count);

	if (!count)
		return 0;

	inode_lock(inode);
	ret = backing_file_write_iter(backing_file, iter, iocb, iocb->ki_flags,
				      &ctx);
	inode_unlock(inode);

	return ret;
}

ssize_t fuse_passthrough_splice_read(struct file *in, loff_t *ppos,
				     struct pipe_inode_info *pipe,
				     size_t len, unsigned int flags)
{
	struct fuse_file *ff = in->private_data;
	struct file *backing_file = fuse_file_passthrough(ff);
	struct backing_file_ctx ctx = {
		.cred = ff->cred,
		.accessed = fuse_file_accessed,
	};

Annotation

Implementation Notes