linux/fs/fuse/iomode.c

// SPDX-License-Identifier: GPL-2.0
/*
 * FUSE inode io modes.
 *
 * Copyright (c) 2024 CTERA Networks.
 */

#include "fuse_i.h"

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/file.h>
#include <linux/fs.h>

/*
 * Return true if need to wait for new opens in caching mode.
 */
static inline bool fuse_is_io_cache_wait(struct fuse_inode *fi)
{ … }

/*
 * Called on cached file open() and on first mmap() of direct_io file.
 * Takes cached_io inode mode reference to be dropped on file release.
 *
 * Blocks new parallel dio writes and waits for the in-progress parallel dio
 * writes to complete.
 */
int fuse_file_cached_io_open(struct inode *inode, struct fuse_file *ff)
{ … }

static void fuse_file_cached_io_release(struct fuse_file *ff,
					struct fuse_inode *fi)
{ … }

/* Start strictly uncached io mode where cache access is not allowed */
int fuse_inode_uncached_io_start(struct fuse_inode *fi, struct fuse_backing *fb)
{ … }

/* Takes uncached_io inode mode reference to be dropped on file release */
static int fuse_file_uncached_io_open(struct inode *inode,
				      struct fuse_file *ff,
				      struct fuse_backing *fb)
{ … }

void fuse_inode_uncached_io_end(struct fuse_inode *fi)
{ … }

/* Drop uncached_io reference from passthrough open */
static void fuse_file_uncached_io_release(struct fuse_file *ff,
					  struct fuse_inode *fi)
{ … }

/*
 * Open flags that are allowed in combination with FOPEN_PASSTHROUGH.
 * A combination of FOPEN_PASSTHROUGH and FOPEN_DIRECT_IO means that read/write
 * operations go directly to the server, but mmap is done on the backing file.
 * FOPEN_PASSTHROUGH mode should not co-exist with any users of the fuse inode
 * page cache, so FOPEN_KEEP_CACHE is a strange and undesired combination.
 */
#define FOPEN_PASSTHROUGH_MASK …

static int fuse_file_passthrough_open(struct inode *inode, struct file *file)
{ … }

/* Request access to submit new io to inode via open file */
int fuse_file_io_open(struct file *file, struct inode *inode)
{ … }

/* No more pending io and no new io possible to inode via open/mmapped file */
void fuse_file_io_release(struct fuse_file *ff, struct inode *inode)
{ … }