path: root/fs/nfs/file.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 *  linux/fs/nfs/file.c
 *
 *  Copyright (C) 1992  Rick Sladkey
 *
 *  Changes Copyright (C) 1994 by Florian La Roche
 *   - Do not copy data too often around in the kernel.
 *   - In nfs_file_read the return value of kmalloc wasn't checked.
 *   - Put in a better version of read look-ahead buffering. Original idea
 *     and implementation by Wai S Kok elekokws@ee.nus.sg.
 *
 *  Expire cache on write to a file by Wai S Kok (Oct 1994).
 *
 *  Total rewrite of read side for new NFS buffer cache.. Linus.
 *
 *  nfs regular file handling functions
 */

#include <linux/module.h>
#include <linux/time.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/fcntl.h>
#include <linux/stat.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_mount.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/gfp.h>
#include <linux/rmap.h>
#include <linux/swap.h>
#include <linux/compaction.h>

#include <linux/uaccess.h>
#include <linux/filelock.h>

#include "delegation.h"
#include "internal.h"
#include "iostat.h"
#include "fscache.h"
#include "pnfs.h"

#include "nfstrace.h"

#define NFSDBG_FACILITY		NFSDBG_FILE

static const struct vm_operations_struct nfs_file_vm_ops;

int nfs_check_flags(int flags)
{
	if ((flags & (O_APPEND | O_DIRECT)) == (O_APPEND | O_DIRECT))
		return -EINVAL;

	return 0;
}
EXPORT_SYMBOL_GPL(nfs_check_flags);

/*
 * Open file
 */
static int
nfs_file_open(struct inode *inode, struct file *filp)
{
	int res;

	dprintk("NFS: open file(%pD2)\n", filp);

	nfs_inc_stats(inode, NFSIOS_VFSOPEN);
	res = nfs_check_flags(filp->f_flags);
	if (res)
		return res;

	res = nfs_open(inode, filp);
	if (res == 0)
		filp->f_mode |= FMODE_CAN_ODIRECT;
	return res;
}

int
nfs_file_release(struct inode *inode, struct file *filp)
{
	dprintk("NFS: release(%pD2)\n", filp);

	nfs_inc_stats(inode, NFSIOS_VFSRELEASE);
	nfs_file_clear_open_context(filp);
	nfs_fscache_release_file(inode, filp);
	return 0;
}
EXPORT_SYMBOL_GPL(nfs_file_release);

/**
 * nfs_revalidate_file_size - Revalidate the file size
 * @inode: pointer to inode struct
 * @filp: pointer to struct file
 *
 * Revalidates the file length. This is basically a wrapper around
 * nfs_revalidate_inode() that takes into account the fact that we may
 * have cached writes (in which case we don't care about the server's
 * idea of what the file length is), or O_DIRECT (in which case we
 * shouldn't trust the cache).
 */
static int nfs_revalidate_file_size(struct inode *inode, struct file *filp)
{
	struct nfs_server *server = NFS_SERVER(inode);

	if (filp->f_flags & O_DIRECT)
		goto force_reval;
	if (nfs_check_cache_invalid(inode, NFS_INO_INVALID_SIZE))
		goto force_reval;
	return 0;
force_reval:
	return __nfs_revalidate_inode(server, inode);
}

loff_t nfs_file_llseek(struct file *filp, loff_t offset, int whence)
{
	dprintk("NFS: llseek file(%pD2, %lld, %d)\n",
			filp, offset, whence);

	/*
	 * whence == SEEK_END || SEEK_DATA || SEEK_HOLE => we must revalidate
	 * the cached file length
	 */
	if (whence != SEEK_SET && whence != SEEK_CUR) {
		struct inode *inode = filp->f_mapping->host;

		int retval = nfs_revalidate_file_size(inode, filp);
		if (retval < 0)
			return (loff_t)retval;
	}

	return generic_file_llseek(filp, offset, whence);
}
EXPORT_SYMBOL_GPL(nfs_file_llseek);

/*
 * Flush all dirty pages, and check for write errors.
 */
static int
nfs_file_flush(struct file *file, fl_owner_t id)
{
	struct inode	*inode = file_inode(file);
	errseq_t since;

	dprintk("NFS: flush(%pD2)\n", file);

	nfs_inc_stats(inode, NFSIOS_VFSFLUSH);
	if ((file->f_mode & FMODE_WRITE) == 0)
		return 0;

	/* Flush writes to the server and return any errors */
	since = filemap_sample_wb_err(file->f_mapping);
	nfs_wb_all(inode);
	return filemap_check_wb_err(file->f_mapping, since);
}

ssize_t
nfs_file_read(struct kiocb *iocb, struct iov_iter *to)
{
	struct inode *inode = file_inode(iocb->ki_filp);
	ssize_t result;

	trace_nfs_file_read(iocb, to);

	if (iocb->ki_flags & IOCB_DIRECT)
		return nfs_file_direct_read(iocb, to, false);

	dprintk("NFS: read(%pD2, %zu@%lu)\n",
		iocb->ki_filp,
		iov_iter_count(to), (unsigned long) iocb->ki_pos);

	result = nfs_start_io_read(inode);
	if (result)
		return result;

	result = nfs_revalidate_mapping(inode, iocb->ki_filp->f_mapping);
	if (!result) {
		result = generic_file_read_iter(iocb, to);
		if (result >