/*
* linux/fs/block_dev.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*/
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/locks.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <asm/segment.h>
#include <asm/system.h>
extern int *blk_size[];
extern int *blksize_size[];
#define MAX_BUF_PER_PAGE (PAGE_SIZE / 512)
#define NBUF 64
int block_write(struct inode * inode, struct file * filp,
const char * buf, int count)
{
int blocksize, blocksize_bits, i, buffercount,write_error;
int block, blocks;
loff_t offset;
int chars;
int written = 0;
struct buffer_head * bhlist[NBUF];
unsigned int size;
kdev_t dev;
struct buffer_head * bh, *bufferlist[NBUF];
register char * p;
write_error = buffercount = 0;
dev = inode->i_rdev;
if ( is_read_only( inode->i_rdev ))
return -EPERM;
blocksize = BLOCK_SIZE;
if (blksize_size[MAJOR(dev)] && blksize_size[MAJOR(dev)][MINOR(dev)])
blocksize = blksize_size[MAJOR(dev)][MINOR(dev)];
i = blocksize;
blocksize_bits = 0;
while(i != 1) {
blocksize_bits++;
i >>= 1;
}
block = filp->f_pos >> blocksize_bits;
offset = filp->f_pos & (blocksize-1);
if (blk_size[MAJOR(dev)])
size = ((loff_t) blk_size[MAJOR(dev)][MINOR(dev)] << BLOCK_SIZE_BITS) >> blocksize_bits;
else
size = INT_MAX;
while (count>0) {
if (block >= size)
return written ? written : -ENOSPC;
chars = blocksize - offset;
if (chars > count)
chars=count;
#if 0
/* get the buffer head */
{
struct buffer_head * (*fn)(kdev_t, int, int) = getblk;
if (chars != blocksize)
fn = bread;
bh = fn(dev, block, blocksize);
}
#else
bh = getblk(dev, block, blocksize);
if (chars != blocksize && !buffer_uptodate(bh)) {
if(!filp->f_reada ||
!read_ahead[MAJOR(dev)]) {
/* We do this to force the read of a single buffer */
brelse(bh);
bh = bread(dev,block,blocksize);
} else {
/* Read-ahead before write */
blocks = read_ahead[MAJOR(dev)] / (blocksize >> 9) / 2;
if (block + blocks > size) blocks = size - block;
if (blocks > NBUF) blocks=NBUF;
bhlist[0] = bh;
for(i=1; i<blocks; i++){
bhlist[i] = getblk (dev, block+i, blocksize);
if(!bhlist[i]){
while(i >= 0) brelse(bhlist[i--]);
return written ? written : -EIO;
};
};
ll_rw_block(READ, blocks, bhlist);
for(i=1; i<blocks; i++) brelse(bhlist[i]);
wait_on_buffer(bh);
};
};
#endif
block++;
if (!bh)
return written ? written : -EIO;
p = offset + bh->b_data;
offset = 0;
filp->f_pos += chars;
written += chars;
count -= chars;
memcpy_fromfs(p,buf,chars);
p += chars;
buf += chars;
mark_buffer_uptodate(bh, 1);
mark_buffer_dirty(bh, 0);
if (filp->f_flags & O_SYNC)
bufferlist[buffercount++] = bh;
else
brelse(bh);
if (buffercount == NBUF){
ll_rw_block(WRITE, buffercount, bufferlist);
for(i=0; i<buffercount; i++){
wait_on_buffer(bufferlist[i]);
if (!buffer_uptodate(bufferlist[i]))
write_error=1;
brelse(bufferlist[i]);
}
buffercount=0;
}
if(write_error)
break;
}
if ( buffercount ){
ll_rw_block(WRITE, buffercount, bufferlist);
for(i=0; i<buffercount; i++){
wait_on_buffer(bufferlist[i]);
if (!buffer_uptodate(bufferlist[i]))
write_error=1;
brelse(bufferlist[i]);
}
}
filp->f_reada = 1;
if(write_error)
return -EIO;
return written;
}
int block_read(struct inode * inode, struct file * filp,
char * buf, int count)
{
unsigned int block;
loff_t offset;
int blocksize;
int blocksize_bits, i;
unsigned int blocks, rblocks, left;
int bhrequest, uptodate;
struct buffer_head ** bhb, ** bhe;
struct buffer_head * buflist[NBUF];
struct buffer_head * bhreq[NBUF];
unsigned int chars;
loff_t size;
kdev_t dev;
int read;
dev = inode->i_rdev;
blocksize = BLOCK_SIZE;
if (blksize_size[MAJOR(dev)] && blksize_size[MAJOR(dev)][MINOR(dev)])
blocksize = blksize_size[MAJOR(dev)][MINOR(dev)];
i = blocksize;
blocksize_bits = 0;
while (i != 1) {
blocksize_bits++;
i >>= 1;
}
offset = filp->f_pos;
if (blk_size[MAJOR(dev)])
size = (loff_t) blk_size[MAJOR(dev)][MINOR(dev)] << BLOCK_SIZE_BITS;
else
size = INT_MAX;
if (offset > size)
left = 0;
/* size - offset might not fit into left, so check explicitly. */
else if (size - offset > INT_MAX)
left = INT_MAX;
else
left = size - offset;
if (left > count)
left = count;
if (left <= 0)
return 0;
read = 0;
block = offset >> blocksize_bits;
offset &= blocksize-1;
size >>= blocksize_bits;
rblocks = blocks = (left + offset + blocksize - 1) >> blocksize_bits;
bhb = bhe = buflist;
if (filp->f_reada) {
if (blocks < read_ahead[MAJOR(dev)] / (blocksize >> 9))
blocks = read_ahead[MAJOR(dev)] / (blocksize >> 9);
if (rblocks > blocks)
blocks = rblocks;
}
if (block + blocks > size)
blocks = size - block;
/* We do this in a two stage process. We first try to request
as many blocks as we can, then we wait for the first one to
complete, and then we try to wrap up as many as are actually
done. This routine is rather generic, in that it can be used
in a filesystem by substituting the appropriate function in
for getblk.
This routine is optimized to make maximum use of the various
buffers and caches. */
do {
bhrequest = 0;
uptodate = 1;
while (blocks) {
--blocks;
*bhb = getblk(dev, block++, blocksize);
if (*bhb && !buffer_uptodate(*bhb)) {
uptodate = 0;
bhreq[bhrequest++] = *bhb;
}
if (++bhb == &buflist[NBUF])
bhb = buflist;
/* If the block we have on hand is uptodate, go ahead
and complete processing. */
if (uptodate)
break;
if (bhb == bhe)
break;
}
/* Now request them all */
if (bhrequest) {
ll_rw_block(READ, bhrequest, bhreq);
}
do { /* Finish off all I/O that has actually completed */
if (*bhe) {
wait_on_buffer(*bhe);
if (!buffer_uptodate(*bhe)) { /* read error? */
brelse(*bhe);
if (++bhe == &buflist[NBUF])
bhe = buflist;
left = 0;
break;
}
}
if (left < blocksize - offset)
chars = left;
else
chars = blocksize - offset;
filp->f_pos += chars;
left -= chars;
read += chars;
if (*bhe) {
memcpy_tofs(buf,offset+(*bhe)->b_data,chars);
brelse(*bhe);
buf += chars;
} else {
while (chars-- > 0)
put_user(0,buf++);
}
offset = 0;
if (++bhe == &buflist[NBUF])
bhe = buflist;
} while (left > 0 && bhe != bhb && (!*bhe || !buffer_locked(*bhe)));
} while (left > 0);
/* Release the read-ahead blocks */
while (bhe != bhb) {
brelse(*bhe);
if (++bhe == &buflist[NBUF])
bhe = buflist;
};
if (!read)
return -EIO;
filp->f_reada = 1;
return read;
}
int block_fsync(struct inode *inode, struct file *filp)
{
return fsync_dev (inode->i_rdev);
}
