Idézet:

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ssize_t
block_read(struct file *filp, char *buf, size_t count, loff_t *ppos) {
struct inode *inode = filp->f_dentry->d_inode;
kdev_t dev = inode->i_rdev;
ssize_t blocksize = blksize_size[MAJOR(dev)][MINOR(dev)];
loff_t offset = *ppos;
ssize_t read = 0;
size_t left, block, blocks;
struct buffer_head *bhreq[NBUF];
struct buffer_head *buflist[NBUF];
struct buffer_head **bh;

left = count; /* bytes to read */
block = offset / blocksize; /* first block */
offset &= (blocksize-1); /* starting offset in block */
blocks = (left + offset + blocksize - 1) / blocksize;

bh = buflist;
do {
while (blocks) {
--blocks;
*bh = getblk(dev, block++, blocksize);
if (*bh && !buffer_uptodate(*bh))
bhreq[bhrequest++] = *bh;
}
if (bhrequest)
ll_rw_block(READ, bhrequest, bhreq);
/* wait for I/O to complete,
copy result to user space,
increment read and *ppos, decrement left */
} while (left > 0);
return read;
}

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