/*
* linux/fs/fat/file.c
*
* Written 1992,1993 by Werner Almesberger
*
* regular file handling primitives for fat-based filesystems
*/
#include <linux/sched.h>
#include <linux/locks.h>
#include <linux/fs.h>
#include <linux/msdos_fs.h>
#include <linux/errno.h>
#include <linux/fcntl.h>
#include <linux/stat.h>
#include <linux/string.h>
#include <linux/pagemap.h>
#include <asm/segment.h>
#include <asm/system.h>
#include "msbuffer.h"
#define MIN(a,b) (((a) < (b)) ? (a) : (b))
#define MAX(a,b) (((a) > (b)) ? (a) : (b))
#define PRINTK(x)
#define Printk(x) printk x
static struct file_operations fat_file_operations = {
NULL, /* lseek - default */
fat_file_read, /* read */
fat_file_write, /* write */
NULL, /* readdir - bad */
NULL, /* select - default */
NULL, /* ioctl - default */
generic_file_mmap, /* mmap */
NULL, /* no special open is needed */
NULL, /* release */
file_fsync /* fsync */
};
struct inode_operations fat_file_inode_operations = {
&fat_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 */
generic_readpage, /* readpage */
NULL, /* writepage */
fat_bmap, /* bmap */
fat_truncate, /* truncate */
NULL, /* permission */
NULL /* smap */
};
/* #Specification: msdos / special devices / mmap
Mmapping does work because a special mmap is provide in that case.
Note that it is much less efficient than the generic_file_mmap normally
used since it allocate extra buffer. generic_file_mmap is used for
normal device (512 bytes hardware sectors).
*/
static struct file_operations fat_file_operations_1024 = {
NULL, /* lseek - default */
fat_file_read, /* read */
fat_file_write, /* write */
NULL, /* readdir - bad */
NULL, /* select - default */
NULL, /* ioctl - default */
fat_mmap, /* mmap */
NULL, /* no special open is needed */
NULL, /* release */
file_fsync /* fsync */
};
/* #Specification: msdos / special devices / swap file
Swap file can't work on special devices with a large sector
size (1024 bytes hard sector). Those devices have a weird
MsDOS filesystem layout. Generally a single hardware sector
may contain 2 unrelated logical sector. This mean that there is
no easy way to do a mapping between disk sector of a file and virtual
memory. So swap file is difficult (not available right now)
on those devices. Off course, Ext2 does not have this problem.
*/
struct inode_operations fat_file_inode_operations_1024 = {
&fat_file_operations_1024, /* 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, /* readpage */
NULL, /* writepage */
NULL, /* bmap */
fat_truncate, /* truncate */
NULL, /* permission */
NULL /* smap */
};
#define MSDOS_PREFETCH 32
struct fat_pre {
int file_sector;/* Next sector to read in the prefetch table */
/* This is relative to the file, not the disk */
struct buffer_head *bhlist[MSDOS_PREFETCH]; /* All buffers needed */
int nblist; /* Number of buffers in bhlist */
int nolist; /* index in bhlist */
};
/*
Order the prefetch of more sectors.
*/
static void fat_prefetch (
struct inode *inode,
struct fat_pre *pre,
int nb) /* How many must we prefetch at once */
{
struct super_block *sb = inode->i_sb;
struct buffer_head *bhreq[MSDOS_PREFETCH]; /* Buffers not */
/* already read */
int nbreq = 0; /* Number of buffers in bhreq */
int i;
for (i=0; i<nb; i++){
int sector = fat_smap(inode,pre->file_sector);
if (sector != 0){
struct buffer_head *bh;
PRINTK (("fsector2 %d -> %d\n",pre->file_sector-1,sector));
pre->file_sector++;
bh = fat_getblk(sb, sector);
if (bh == NULL) break;
pre->bhlist[pre->nblist++] = bh;
if (!fat_is_uptodate(sb,bh))
bhreq[nbreq++] = bh;
}else{
break;
}
}
if (nbreq > 0) fat_ll_rw_block (sb,READ,nbreq,bhreq);
for (i=pre->nblist; i<MSDOS_PREFETCH; i++) pre->bhlist[i] = NULL;
}
/*
Read a file into user space
*/
int fat_file_read(
struct inode *inode,
struct file *filp,
char *buf,
int count)
{
struct super_block *sb = inode->i_sb;
char *start = buf;
char *end = buf + count;
int i;
int left_in_file;
struct fat_pre pre;
if (!inode) {
printk("fat_file_read: inode = NULL\n");
return -EINVAL;
}
/* S_ISLNK allows for UMSDOS. Should never happen for normal MSDOS */
if (!S_ISREG(inode->i_mode) && !S_ISLNK(inode->i_mode)) {
printk("fat_file_read: mode = %07o\n",inode->i_mode);
return -EINVAL;
}
if (filp->f_pos >= inode->i_size || count <= 0) return 0;
/*
Tell the buffer cache which block we expect to read in advance
Since we are limited with the stack, we preread only MSDOS_PREFETCH
because we have to keep the result into the local
arrays pre.bhlist and bhreq.
Each time we process one block in bhlist, we replace
it by a new prefetch block if needed.
*/
PRINTK (("#### ino %ld pos %ld size %ld count %d\n",inode->i_ino,filp->f_pos,inode->i_size,count));
{
/*
We must prefetch complete block, so we must
take in account the offset in the first block.
*/
int count_max = (filp->f_pos & (SECTOR_SIZE-1)) + count;
int to_reada; /* How many block to read all at once */
pre.file_sector = filp->f_pos >> SECTOR_BITS;
to_reada = count_max / SECTOR_SIZE;
if (count_max & (SECTOR_SIZE-1)) to_reada++;
if (filp->f_reada || !MSDOS_I(inode)->i_binary){
/* Doing a read ahead on ascii file make sure we always */
/* pre read enough, since we don't know how many blocks */
/* we really need */
int ahead = read_ahead[MAJOR(inode->i_dev)];
PRINTK (("to_reada %d ahead %d\n",to_reada,ahead));
if (ahead == 0) ahead = 8;
to_reada += ahead;
}
if (to_reada > MSDOS_PREFETCH) to_reada = MSDOS_PREFETCH;
pre.nblist = 0;
fat_prefetch (inode,&pre,to_reada);
}
pre.nolist = 0;
PRINTK (("count %d ahead %d nblist %d\n",count,read_ahead[MAJOR(inode->i_dev)],pre.nblist));
while ((left_in_file = inode->i_size - filp->f_pos) > 0
&& buf < end){
struct buffer_head *bh = pre.bhlist[pre.nolist];
char *data;
int size,offset;
if (bh == NULL) break;
pre.bhlist[pre.nolist] = NULL;
pre.nolist++;
if (pre.nolist == MSDOS_PREFETCH/2){
memcpy (pre.bhlist,pre.bhlist+MSDOS_PREFETCH/2
,(MSDOS_PREFETCH/2)*sizeof(pre.bhlist[0]));
pre.nblist -= MSDOS_PREFETCH/2;
fat_prefetch (inode,&pre,MSDOS_PREFETCH/2);
pre.nolist = 0;
}
PRINTK (("file_read pos %ld nblist %d %d %d\n",filp->f_pos,pre.nblist,pre.fetched,count));
wait_on_buffer(bh);
if (!fat_is_uptodate(sb,bh)){
/* read error ? */
fat_brelse (sb, bh);
break;
}
offset = filp->f_pos & (SECTOR_SIZE-1);
data = bh->b_data + offset;
size = MIN(SECTOR_SIZE-offset,left_in_file);
if (MSDOS_I(inode)->i_binary) {
size = MIN(size,end-buf);
memcpy_tofs(buf,data,size);
buf += size;
filp->f_pos += size;
}else{
for (; size && buf < end; size--) {
char ch = *data++;
filp->f_pos++;
if (ch == 26){
filp->f_pos = inode->i_size;
break;
}else if (ch != '\r'){
put_user(ch,buf++);
}
}
}
fat_brelse(sb, bh);
}
PRINTK (("--- %d -> %d\n",count,(int)(buf-start)));
for (i=0; i<pre.nblist; i++)
fat_brelse (sb, pre.bhlist[i]);
if (start == buf)
return -EIO;
if (!IS_RDONLY(inode))
inode->i_atime = CURRENT_TIME;
filp->f_reada = 1; /* Will be reset if a lseek is done */
return buf-start;
}
/*
Write to a file either from user space
*/
int fat_file_write(
struct inode *inode,
struct file *filp,
const char *buf,
int count)
{
struct super_block *sb = inode->i_sb;
int sector,offset,size,left,written;
int error,carry;
const char *start;
char *to,ch;
struct buffer_head *bh;
int binary_mode = MSDOS_I(inode)->i_binary;
if (!inode) {
printk("fat_file_write: inode = NULL\n");
return -EINVAL;
}
/* S_ISLNK allows for UMSDOS. Should never happen for normal MSDOS */
if (!S_ISREG(inode->i_mode) && !S_ISLNK(inode->i_mode)) {
printk("fat_file_write: mode = %07o\n",inode->i_mode);
return -EINVAL;
}
/* system files may be immutable */
if (IS_IMMUTABLE(inode))
return -EPERM;
/*
* ok, append may not work when many processes are writing at the same time
* but so what. That way leads to madness anyway.
*/
if (filp->f_flags & O_APPEND)
filp->f_pos = inode->i_size;
if (count <= 0)
return 0;
error = carry = 0;
for (start = buf; count || carry; count -= size) {
while (!(sector = fat_smap(inode,filp->f_pos >> SECTOR_BITS)))
if ((error = fat_add_cluster(inode)) < 0) break;
if (error) {
fat_truncate(inode);
break;
}
offset = filp->f_pos & (SECTOR_SIZE-1);
size = MIN(SECTOR_SIZE-offset,MAX(carry,count));
if (binary_mode
&& offset == 0
&& (size == SECTOR_SIZE
|| filp->f_pos + size >= inode->i_size)){
/* No need to read the block first since we will */
/* completely overwrite it */
/* or at least write past the end of file */
if (!(bh = fat_getblk(sb,sector))){
error = -EIO;
break;
}
} else if (!(bh = fat_bread(sb,sector))) {
error = -EIO;
break;
}
if (binary_mode) {
memcpy_fromfs(bh->b_data+offset,buf,written = size);
buf += size;
} else {
written = left = SECTOR_SIZE-offset;
to = (char *) bh->b_data+(filp->f_pos & (SECTOR_SIZE-1));
if (carry) {
*to++ = '\n';
left--;
carry = 0;
}
for (size = 0; size < count && left; size++) {
if ((ch = get_user(buf++)) == '\n') {
*to++ = '\r';
left--;
}
if (!left) carry = 1;
else {
*to++ = ch;
left--;
}
}
written -= left;
}
update_vm_cache(inode, filp->f_pos, bh->b_data + (filp->f_pos & (SECTOR_SIZE-1)), written);
filp->f_pos += written;
if (filp->f_pos > inode->i_size) {
inode->i_size = filp->f_pos;
inode->i_dirt = 1;
}
fat_set_uptodate(sb, bh, 1);
fat_mark_buffer_dirty(sb, bh, 0);
fat_brelse(sb, bh);
}
if (start == buf)
return error;
inode->i_mtime = inode->i_ctime = CURRENT_TIME;
MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
inode->i_dirt = 1;
return buf-start;
}
void fat_truncate(struct inode *inode)
{
int cluster;
/* Why no return value? Surely the disk could fail... */
if (IS_IMMUTABLE(inode))
return /* -EPERM */;
cluster = SECTOR_SIZE*MSDOS_SB(inode->i_sb)->cluster_size;
(void) fat_free(inode,(inode->i_size+(cluster-1))/cluster);
MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
inode->i_dirt = 1;
}
