mm/truncate: add parameter explanation for invalidate_mapping_pagevec

To fix a kernel-doc markups issue:

  mm/truncate.c:646: warning: Function parameter or member 'mapping' not described in 'invalidate_mapping_pagevec'
  mm/truncate.c:646: warning: Function parameter or member 'start' not described in 'invalidate_mapping_pagevec'
  mm/truncate.c:646: warning: Function parameter or member 'end' not described in 'invalidate_mapping_pagevec'
  mm/truncate.c:646: warning: Function parameter or member 'nr_pagevec' not described in 'invalidate_mapping_pagevec'

Link: https://lkml.kernel.org/r/1605605088-30668-1-git-send-email-alex.shi@linux.alibaba.comSigned-off-by: NAlex Shi <alex.shi@linux.alibaba.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/truncate.c

@@ -637,9 +637,15 @@ unsigned long invalidate_mapping_pages(struct address_space *mapping,
 EXPORT_SYMBOL(invalidate_mapping_pages);
 
 /**
- * This helper is similar with the above one, except that it accounts for pages
- * that are likely on a pagevec and count them in @nr_pagevec, which will used by
- * the caller.
+ * invalidate_mapping_pagevec - Invalidate all the unlocked pages of one inode
+ * @mapping: the address_space which holds the pages to invalidate
+ * @start: the offset 'from' which to invalidate
+ * @end: the offset 'to' which to invalidate (inclusive)
+ * @nr_pagevec: invalidate failed page number for caller
+ *
+ * This helper is similar with invalidate_mapping_pages, except that it accounts
+ * for pages that failed to invalidate on a pagevec and count them in
+ * @nr_pagevec, which will used by the caller.
  */
 void invalidate_mapping_pagevec(struct address_space *mapping,
 		pgoff_t start, pgoff_t end, unsigned long *nr_pagevec)