87 lines
1.8 KiB
C
87 lines
1.8 KiB
C
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#include <errno.h>
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#include <linux/fs.h>
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#include <linux/kernel.h>
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#include <asm/segment.h>
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#define NR_BLK_DEV ((sizeof (rd_blk))/(sizeof (rd_blk[0])))
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int block_write(int dev, long * pos, char * buf, int count)
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{
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int block = *pos / BLOCK_SIZE;
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int offset = *pos % BLOCK_SIZE;
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int chars;
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int written = 0;
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struct buffer_head * bh;
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register char * p;
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while (count>0) {
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bh = bread(dev,block);
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if (!bh)
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return written?written:-EIO;
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chars = (count<BLOCK_SIZE) ? count : BLOCK_SIZE;
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p = offset + bh->b_data;
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offset = 0;
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block++;
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*pos += chars;
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written += chars;
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count -= chars;
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while (chars-->0)
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*(p++) = get_fs_byte(buf++);
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bh->b_dirt = 1;
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brelse(bh);
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}
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return written;
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}
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int block_read(int dev, unsigned long * pos, char * buf, int count)
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{
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int block = *pos / BLOCK_SIZE;
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int offset = *pos % BLOCK_SIZE;
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int chars;
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int read = 0;
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struct buffer_head * bh;
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register char * p;
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while (count>0) {
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bh = bread(dev,block);
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if (!bh)
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return read?read:-EIO;
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chars = (count<BLOCK_SIZE) ? count : BLOCK_SIZE;
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p = offset + bh->b_data;
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offset = 0;
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block++;
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*pos += chars;
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read += chars;
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count -= chars;
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while (chars-->0)
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put_fs_byte(*(p++),buf++);
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bh->b_dirt = 1;
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brelse(bh);
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}
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return read;
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}
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extern void rw_hd(int rw, struct buffer_head * bh);
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typedef void (*blk_fn)(int rw, struct buffer_head * bh);
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static blk_fn rd_blk[]={
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NULL, /* nodev */
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NULL, /* dev mem */
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NULL, /* dev fd */
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rw_hd, /* dev hd */
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NULL, /* dev ttyx */
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NULL, /* dev tty */
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NULL}; /* dev lp */
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void ll_rw_block(int rw, struct buffer_head * bh)
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{
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blk_fn blk_addr;
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unsigned int major;
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if ((major=MAJOR(bh->b_dev)) >= NR_BLK_DEV || !(blk_addr=rd_blk[major]))
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panic("Trying to read nonexistent block-device");
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blk_addr(rw, bh);
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}
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