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/*
* 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).
*
* nfs regular file handling functions
*/
#include <asm/segment.h>
#include <asm/system.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/fcntl.h>
#include <linux/stat.h>
#include <linux/mm.h>
#include <linux/nfs_fs.h>
#include <linux/malloc.h>
static int nfs_file_read(struct inode *, struct file *, char *, int);
static int nfs_file_write(struct inode *, struct file *, char *, int);
static int nfs_fsync(struct inode *, struct file *);
static struct file_operations nfs_file_operations = {
NULL, /* lseek - default */
nfs_file_read, /* read */
nfs_file_write, /* write */
NULL, /* readdir - bad */
NULL, /* select - default */
NULL, /* ioctl - default */
nfs_mmap, /* mmap */
NULL, /* no special open is needed */
NULL, /* release */
nfs_fsync, /* fsync */
};
struct inode_operations nfs_file_inode_operations = {
&nfs_file_operations, /* default file operations */
NULL, /* create */
NULL, /* lookup */
NULL, /* link */
NULL, /* unlink */
NULL, /* symlink */
NULL, /* mkdir */
NULL, /* rmdir */
NULL, /* mknod */
NULL, /* rename */
NULL, /* readlink */
NULL, /* follow_link */
NULL, /* bmap */
NULL /* truncate */
};
/* Once data is inserted, it can only be deleted, if (in_use==0). */
struct read_cache {
int in_use; /* currently in use? */
unsigned long inode_num; /* inode number */
off_t file_pos; /* file position */
int len; /* size of data */
unsigned long time; /* time, this entry was inserted */
char * buf; /* data */
int buf_size; /* size of buffer */
};
#define READ_CACHE_SIZE 5
#define EXPIRE_CACHE (HZ * 3) /* keep no longer than 3 seconds */
unsigned long num_requests = 0;
unsigned long num_cache_hits = 0;
static int tail = 0; /* next cache slot to replace */
static struct read_cache cache[READ_CACHE_SIZE] = {
{ 0, 0, -1, 0, 0, NULL, 0 },
{ 0, 0, -1, 0, 0, NULL, 0 },
{ 0, 0, -1, 0, 0, NULL, 0 },
{ 0, 0, -1, 0, 0, NULL, 0 },
{ 0, 0, -1, 0, 0, NULL, 0 } };
static int nfs_fsync(struct inode *inode, struct file *file)
{
return 0;
}
static int nfs_file_read(struct inode *inode, struct file *file, char *buf,
int count)
{
int result, hunk, i, n, fs;
struct nfs_fattr fattr;
char *data;
off_t pos;
if (!inode) {
printk("nfs_file_read: inode = NULL\n");
return -EINVAL;
}
if (!S_ISREG(inode->i_mode)) {
printk("nfs_file_read: read from non-file, mode %07o\n",
inode->i_mode);
return -EINVAL;
}
pos = file->f_pos;
if (pos + count > inode->i_size)
count = inode->i_size - pos;
if (count <= 0)
return 0;
++num_requests;
cli();
for (i = 0; i < READ_CACHE_SIZE; i++)
if ((cache[i].inode_num == inode->i_ino)
&& (cache[i].file_pos <= pos)
&& (cache[i].file_pos + cache[i].len >= pos + count)
&& (abs(jiffies - cache[i].time) <= EXPIRE_CACHE))
break;
if (i < READ_CACHE_SIZE) {
++cache[i].in_use;
sti();
++num_cache_hits;
memcpy_tofs(buf, cache[i].buf + pos - cache[i].file_pos, count);
--cache[i].in_use;
file->f_pos += count;
return count;
}
sti();
n = NFS_SERVER(inode)->rsize;
for (i = 0; i < count - n; i += n) {
result = nfs_proc_read(NFS_SERVER(inode), NFS_FH(inode),
pos, n, buf, &fattr, 1);
if (result < 0)
return result;
pos += result;
buf += result;
if (result < n) {
file->f_pos = pos;
nfs_refresh_inode(inode, &fattr);
return i + result;
}
}
fs = 0;
if (!(data = (char *)kmalloc(n, GFP_KERNEL))) {
data = buf;
fs = 1;
}
result = nfs_proc_read(NFS_SERVER(inode), NFS_FH(inode),
pos, n, data, &fattr, fs);
if (result < 0) {
if (!fs)
kfree_s(data, n);
return result;
}
hunk = count - i;
if (result < hunk)
hunk = result;
if (fs) {
file->f_pos = pos + hunk;
nfs_refresh_inode(inode, &fattr);
return i + hunk;
}
memcpy_tofs(buf, data, hunk);
file->f_pos = pos + hunk;
nfs_refresh_inode(inode, &fattr);
cli();
if (cache[tail].in_use == 0) {
if (cache[tail].buf)
kfree_s(cache[tail].buf, cache[tail].buf_size);
cache[tail].buf = data;
cache[tail].buf_size = n;
cache[tail].inode_num = inode->i_ino;
cache[tail].file_pos = pos;
cache[tail].len = result;
cache[tail].time = jiffies;
if (++tail >= READ_CACHE_SIZE)
tail = 0;
} else
kfree_s(data, n);
sti();
return i + hunk;
}
static int nfs_file_write(struct inode *inode, struct file *file, char *buf,
int count)
{
int result, hunk, i, n, pos;
struct nfs_fattr fattr;
if (!inode) {
printk("nfs_file_write: inode = NULL\n");
return -EINVAL;
}
if (!S_ISREG(inode->i_mode)) {
printk("nfs_file_write: write to non-file, mode %07o\n",
inode->i_mode);
return -EINVAL;
}
if (count <= 0)
return 0;
cli();
/* If hit, cache is dirty and must be expired. */
for (i = 0; i < READ_CACHE_SIZE; i++)
if(cache[i].inode_num == inode->i_ino)
cache[i].time -= EXPIRE_CACHE;
sti();
pos = file->f_pos;
if (file->f_flags & O_APPEND)
pos = inode->i_size;
n = NFS_SERVER(inode)->wsize;
for (i = 0; i < count; i += n) {
hunk = count - i;
if (hunk >= n)
hunk = n;
result = nfs_proc_write(NFS_SERVER(inode), NFS_FH(inode),
pos, hunk, buf, &fattr);
if (result < 0)
return result;
pos += hunk;
buf += hunk;
if (hunk < n) {
i += hunk;
break;
}
}
file->f_pos = pos;
nfs_refresh_inode(inode, &fattr);
return i;
}
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