// 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,	};	struct kiocb iocb;	ssize_t ret; 	pr_debug("%s: backing_file=0x%p, pos=%lld, len=%zu, flags=0x%x\n", __func__,		 backing_file, *ppos, len, flags); 	init_sync_kiocb(&iocb, in);	iocb.ki_pos = *ppos;	ret = backing_file_splice_read(backing_file, &iocb, pipe, len, flags, &ctx);	*ppos = iocb.ki_pos; 	return ret;} ssize_t fuse_passthrough_splice_write(struct pipe_inode_info *pipe,				      struct file *out, loff_t *ppos,				      size_t len, unsigned int flags){	struct fuse_file *ff = out->private_data;	struct file *backing_file = fuse_file_passthrough(ff);	struct inode *inode = file_inode(out);	ssize_t ret;	struct backing_file_ctx ctx = {		.cred = ff->cred,		.end_write = fuse_passthrough_end_write,	};	struct kiocb iocb; 	pr_debug("%s: backing_file=0x%p, pos=%lld, len=%zu, flags=0x%x\n", __func__,		 backing_file, *ppos, len, flags); 	inode_lock(inode);	init_sync_kiocb(&iocb, out);	iocb.ki_pos = *ppos;	ret = backing_file_splice_write(pipe, backing_file, &iocb, len, flags, &ctx);	*ppos = iocb.ki_pos;	inode_unlock(inode); 	return ret;} ssize_t fuse_passthrough_mmap(struct file *file, struct vm_area_struct *vma){	struct fuse_file *ff = file->private_data;	struct file *backing_file = fuse_file_passthrough(ff);	struct backing_file_ctx ctx = {		.cred = ff->cred,		.accessed = fuse_file_accessed,	}; 	pr_debug("%s: backing_file=0x%p, start=%lu, end=%lu\n", __func__,		 backing_file, vma->vm_start, vma->vm_end); 	return backing_file_mmap(backing_file, vma, &ctx);} /* * Setup passthrough to a backing file. * * Returns an fb object with elevated refcount to be stored in fuse inode. */struct fuse_backing *fuse_passthrough_open(struct file *file, int backing_id){	struct fuse_file *ff = file->private_data;	struct fuse_conn *fc = ff->fm->fc;	struct fuse_backing *fb = NULL;	struct file *backing_file;	int err; 	err = -EINVAL;	if (backing_id <= 0)		goto out; 	err = -ENOENT;	fb = fuse_backing_lookup(fc, backing_id);	if (!fb)		goto out; 	/* Allocate backing file per fuse file to store fuse path */	backing_file = backing_file_open(file, file->f_flags,					 &fb->file->f_path, fb->cred);	err = PTR_ERR(backing_file);	if (IS_ERR(backing_file)) {		fuse_backing_put(fb);		goto out;	} 	err = 0;	ff->passthrough = backing_file;	ff->cred = get_cred(fb->cred);out:	pr_debug("%s: backing_id=%d, fb=0x%p, backing_file=0x%p, err=%i\n", __func__,		 backing_id, fb, ff->passthrough, err); 	return err ? ERR_PTR(err) : fb;} void fuse_passthrough_release(struct fuse_file *ff, struct fuse_backing *fb){	pr_debug("%s: fb=0x%p, backing_file=0x%p\n", __func__,		 fb, ff->passthrough); 	fput(ff->passthrough);	ff->passthrough = NULL;	put_cred(ff->cred);	ff->cred = NULL;}