block_invalidatepage — invalidate part of all of a buffer-backed page
void block_invalidatepage ( | struct page * | page, |
| unsigned long | offset); |
block_invalidatepage is called when all or part of the page has become
invalidatedby a truncate operation.
block_invalidatepage does not have to release all buffers, but it must
ensure that no dirty buffer is left outside offset and that no I/O
is underway against any of the blocks which are outside the truncation
point. Because the caller is about to free (and possibly reuse) those
blocks on-disk.