Revert "ceph: don't truncate dirty pages in invalidate work thread"

This reverts commit c9af9fb6.

We need to block and truncate all pages in order to reliably invalidate
them.  Otherwise, we could:

 - have some uptodate pages in the cache
 - queue an invalidate
 - write(2) locks some pages
 - invalidate_work skips them
 - write(2) only overwrites part of the page
 - page now dirty and uptodate
 -> partial leakage of invalidated data

It's not entirely clear why we started skipping locked pages in the first
place.  I just ran this through fsx and didn't see any problems.
Signed-off-by: Sage Weil <sage@newdream.net>

fs/ceph/inode.c

@@ -9,7 +9,6 @@
 #include <linux/namei.h>
 #include <linux/writeback.h>
 #include <linux/vmalloc.h>
-#include <linux/pagevec.h>
 
 #include "super.h"
 #include "mds_client.h"
@@ -1363,49 +1362,6 @@ void ceph_queue_invalidate(struct inode *inode)
 	}
 }
 
-/*
- * invalidate any pages that are not dirty or under writeback.  this
- * includes pages that are clean and mapped.
- */
-static void ceph_invalidate_nondirty_pages(struct address_space *mapping)
-{
-	struct pagevec pvec;
-	pgoff_t next = 0;
-	int i;
-
-	pagevec_init(&pvec, 0);
-	while (pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
-		for (i = 0; i < pagevec_count(&pvec); i++) {
-			struct page *page = pvec.pages[i];
-			pgoff_t index;
-			int skip_page =
-				(PageDirty(page) || PageWriteback(page));
-
-			if (!skip_page)
-				skip_page = !trylock_page(page);
-
-			/*
-			 * We really shouldn't be looking at the ->index of an
-			 * unlocked page.  But we're not allowed to lock these
-			 * pages.  So we rely upon nobody altering the ->index
-			 * of this (pinned-by-us) page.
-			 */
-			index = page->index;
-			if (index > next)
-				next = index;
-			next++;
-
-			if (skip_page)
-				continue;
-
-			generic_error_remove_page(mapping, page);
-			unlock_page(page);
-		}
-		pagevec_release(&pvec);
-		cond_resched();
-	}
-}
-
 /*
  * Invalidate inode pages in a worker thread.  (This can't be done
  * in the message handler context.)
@@ -1429,7 +1385,7 @@ static void ceph_invalidate_work(struct work_struct *work)
 	orig_gen = ci->i_rdcache_gen;
 	spin_unlock(&inode->i_lock);
 
-	ceph_invalidate_nondirty_pages(inode->i_mapping);
+	truncate_inode_pages(&inode->i_data, 0);
 
 	spin_lock(&inode->i_lock);
 	if (orig_gen == ci->i_rdcache_gen &&