radix-tree: delete radix_tree_range_tag_if_tagged()

This is an exceptionally complicated function with just one caller
(tag_pages_for_writeback).  We devote a large portion of the runtime of
the test suite to testing this one function which has one caller.  By
introducing the new function radix_tree_iter_tag_set(), we can eliminate
all of the complexity while keeping the performance.  The caller can now
use a fairly standard radix_tree_for_each() loop, and it doesn't need to
worry about tricksy things like 'start' wrapping.

The test suite continues to spend a large amount of time investigating
this function, but now it's testing the underlying primitives such as
radix_tree_iter_resume() and the radix_tree_for_each_tagged() iterator
which are also used by other parts of the kernel.

Link: http://lkml.kernel.org/r/1480369871-5271-57-git-send-email-mawilcox@linuxonhyperv.com
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Tested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 8 deletions

diff --git a/tools/testing/radix-tree/main.c b/tools/testing/radix-tree/main.c
index a028dae8a043..170175ca4105 100644
--- a/tools/testing/radix-tree/main.c
+++ b/tools/testing/radix-tree/main.c
@@ -205,8 +205,7 @@ void copy_tag_check(void)
 	}
 
 //	printf("\ncopying tags...\n");
-	cur = start;
-	tagged = radix_tree_range_tag_if_tagged(&tree, &cur, end, ITEMS, 0, 1);
+	tagged = tag_tagged_items(&tree, NULL, start, end, ITEMS, 0, 1);
 
 //	printf("checking copied tags\n");
 	assert(tagged == count);
@@ -214,16 +213,13 @@ void copy_tag_check(void)
 
 	/* Copy tags in several rounds */
 //	printf("\ncopying tags...\n");
-	cur = start;
-	do {
-		tmp = rand() % (count/10+2);
-		tagged = radix_tree_range_tag_if_tagged(&tree, &cur, end, tmp, 0, 2);
-	} while (tmp == tagged);
+	tmp = rand() % (count / 10 + 2);
+	tagged = tag_tagged_items(&tree, NULL, start, end, tmp, 0, 2);
+	assert(tagged == count);
 
 //	printf("%lu %lu %lu\n", tagged, tmp, count);
 //	printf("checking copied tags\n");
 	check_copied_tags(&tree, start, end, idx, ITEMS, 0, 2);
-	assert(tagged < tmp);
 	verify_tag_consistency(&tree, 0);
 	verify_tag_consistency(&tree, 1);
 	verify_tag_consistency(&tree, 2);