linux-2.6.33/file_read_actor()

参照元†

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説明†

パス: linux-2.6.33/mm/filemap.c

FIXME: これは何？
- 説明

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引数†

read_descriptor_t *desc
- linux-2.6.33/read_descriptor_t
struct page *page
- linux-2.6.33/page
unsigned long offset
unsigned long size

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返り値†

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参考†

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実装†

int file_read_actor(read_descriptor_t *desc, struct page *page,
			unsigned long offset, unsigned long size)
{
	char *kaddr;
	unsigned long left, count = desc->count;

	if (size > count)
		size = count;

	/*
	 * Faults on the destination of a read are common, so do it before
	 * taking the kmap.
	 */
	if (!fault_in_pages_writeable(desc->arg.buf, size)) {

- linux-2.6.33/fault_in_pages_writeable()

		kaddr = kmap_atomic(page, KM_USER0);
		left = __copy_to_user_inatomic(desc->arg.buf,
						kaddr + offset, size);
		kunmap_atomic(kaddr, KM_USER0);

		if (left == 0)
			goto success;
	}

	/* Do it the slow way */
	kaddr = kmap(page);
	left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
	kunmap(page);

	if (left) {
		size -= left;
		desc->error = -EFAULT;
	}
success:
	desc->count = count - size;
	desc->written += size;
	desc->arg.buf += size;
	return size;
}

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