file.c

/*
 *  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/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/aio.h>
#include <linux/gfp.h>
#include <linux/swap.h>

#include <asm/uaccess.h>

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

#define NFSDBG_FACILITY		NFSDBG_FILE

static const struct vm_operations_struct nfs_file_vm_ops;

const struct inode_operations nfs_file_inode_operations = {
	.permission	= nfs_permission,
	.getattr	= nfs_getattr,
	.setattr	= nfs_setattr,
};

#ifdef CONFIG_NFS_V3
const struct inode_operations nfs3_file_inode_operations = {
	.permission	= nfs_permission,
	.getattr	= nfs_getattr,
	.setattr	= nfs_setattr,
	.listxattr	= nfs3_listxattr,
	.getxattr	= nfs3_getxattr,
	.setxattr	= nfs3_setxattr,
	.removexattr	= nfs3_removexattr,
};
#endif  /* CONFIG_NFS_v3 */

/* Hack for future NFS swap support */
#ifndef IS_SWAPFILE
# define IS_SWAPFILE(inode)	(0)
#endif

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

	return 0;
}

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

	dprintk("NFS: open file(%s/%s)\n",
			filp->f_path.dentry->d_parent->d_name.name,
			filp->f_path.dentry->d_name.name);

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

	res = nfs_open(inode, filp);
	return res;
}

static int
nfs_file_release(struct inode *inode, struct file *filp)
{
	dprintk("NFS: release(%s/%s)\n",
			filp->f_path.dentry->d_parent->d_name.name,
			filp->f_path.dentry->d_name.name);

	nfs_inc_stats(inode, NFSIOS_VFSRELEASE);
	return nfs_release(inode, filp);
}

/**
 * nfs_revalidate_size - Revalidate the file size
 * @inode - pointer to inode struct
 * @file - 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);
	struct nfs_inode *nfsi = NFS_I(inode);

	if (nfs_have_delegated_attributes(inode))
		goto out_noreval;

	if (filp->f_flags & O_DIRECT)
		goto force_reval;
	if (nfsi->cache_validity & NFS_INO_REVAL_PAGECACHE)
		goto force_reval;
	if (nfs_attribute_timeout(inode))
		goto force_reval;
out_noreval:
	return 0;
force_reval:
	return __nfs_revalidate_inode(server, inode);
}

static loff_t nfs_file_llseek(struct file *filp, loff_t offset, int origin)
{
	dprintk("NFS: llseek file(%s/%s, %lld, %d)\n",
			filp->f_path.dentry->d_parent->d_name.name,
			filp->f_path.dentry->d_name.name,
			offset, origin);

	/*
	 * origin == SEEK_END || SEEK_DATA || SEEK_HOLE => we must revalidate
	 * the cached file length
	 */
	if (origin != SEEK_SET && origin != 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, origin);
}

/*
 * Flush all dirty pages, and check for write errors.
 */
static int
nfs_file_flush(struct file *file, fl_owner_t id)
{
	struct dentry	*dentry = file->f_path.dentry;
	struct inode	*inode = dentry->d_inode;

	dprintk("NFS: flush(%s/%s)\n",
			dentry->d_parent->d_name.name,
			dentry->d_name.name);

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

	/*
	 * If we're holding a write delegation, then just start the i/o
	 * but don't wait for completion (or send a commit).
	 */
	if (nfs_have_delegation(inode, FMODE_WRITE))
		return filemap_fdatawrite(file->f_mapping);

	/* Flush writes to the server and return any errors */
	return vfs_fsync(file, 0);
}

static ssize_t
nfs_file_read(struct kiocb *iocb, const struct iovec *iov,
		unsigned long nr_segs, loff_t pos)
{
	struct dentry * dentry = iocb->ki_filp->f_path.dentry;
	struct inode * inode = dentry->d_inode;
	ssize_t result;

	if (iocb->ki_filp->f_flags & O_DIRECT)
		return nfs_file_direct_read(iocb, iov, nr_segs, pos);

	dprintk("NFS: read(%s/%s, %lu@%lu)\n",
		dentry->d_parent->d_name.name, dentry->d_name.name,