page which is affected

block_invalidatepage - invalidate part of all of a buffer-backed page

: the index of the truncation point

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 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.

write_one_page - write out a single page and optionally wait on I/O

: if true, wait on writeout

The page must be locked by the caller and will be unlocked upon return.

write_one_page() returns a negative error code if I/O failed.