mm: add variant of pagevec_lookup_range_tag() taking number of pages

mm: add variant of pagevec_lookup_range_tag() taking number of pages

Currently pagevec_lookup_range_tag() takes number of pages to look up
but most users don't need this.  Create a new function
pagevec_lookup_range_nr_tag() that takes maximum number of pages to
lookup for Ceph which wants this functionality so that we can drop
nr_pages argument from pagevec_lookup_range_tag().

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Jan Kara <[email protected]>
Reviewed-by: Daniel Jordan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>