generic_file_write code segment in 2.2.18

[Asang K Dani <asang@yahoo.com>]

hi everyone,
   I was trying to understand following piece of code in
'generic_file_read' (mm/filemap.c) for 2.2.18 kernel. The code
segment
is as follows:

----------------------------------------------------------------
		dest = (char *) page_address(page) + offset;
		if (dest != buf) { /* See comment in
                                      update_vm_cache_cond. */
			bytes -= copy_from_user(dest, buf, bytes);
			flush_dcache_page(page_address(page));
		}
		status = -EFAULT;
		if (bytes)
			status = inode->i_op->updatepage(file, page,                      
                      offset, bytes, sync);

 unlock:
		/* Mark it unlocked again and drop the page.. */
		clear_bit(PG_locked, &page->flags);
		wake_up(&page->wait);
		page_cache_release(page);

		if (status < 0)
			break;

		written += status;
		count -= status;
		pos += status;
		buf += status;
----------------------------------------------------------------
copy_from_user returns the number of bytes copied from userspace
to 'dest'. In case it succeeds, 'bytes' will be set to 0 after the
call. However, 'status' is set to -EFAULT. So wouldn't it break
out of the while loop (prematurely)?

Please post/CC your comments to me if this is not of general interest
to the list and is too silly to be answered there.

regards,
Asang Dani

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