buffer: handle large folios in __block_write_begin_int()

When __block_write_begin_int() was converted to support folios, we did not
expect large folios to be passed to it.  With the current work to support
large block size storage devices, this will no longer be true so change
the checks on 'from' and 'to' to be related to the size of the folio
instead of PAGE_SIZE.  Also remove an assumption that the block size is
smaller than PAGE_SIZE.

Link: https://lkml.kernel.org/r/20231109210608.2252323-7-willy@infradead.org


Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reported-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Pankaj Raghav <p.raghav@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>