From 268f42de718128cd0301293177e79c08c38e39a6 Mon Sep 17 00:00:00 2001 From: Matthew Wilcox Date: Wed, 14 Dec 2016 15:08:55 -0800 Subject: 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 Tested-by: Kirill A. Shutemov Cc: Konstantin Khlebnikov Cc: Ross Zwisler Cc: Matthew Wilcox Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page-writeback.c | 28 ++++++++++++++++++---------- 1 file changed, 18 insertions(+), 10 deletions(-) (limited to 'mm/page-writeback.c') diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 52e2f8e3b472..290e8b7d3181 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -2106,18 +2106,26 @@ void tag_pages_for_writeback(struct address_space *mapping, pgoff_t start, pgoff_t end) { #define WRITEBACK_TAG_BATCH 4096 - unsigned long tagged; - - do { - spin_lock_irq(&mapping->tree_lock); - tagged = radix_tree_range_tag_if_tagged(&mapping->page_tree, - &start, end, WRITEBACK_TAG_BATCH, - PAGECACHE_TAG_DIRTY, PAGECACHE_TAG_TOWRITE); + unsigned long tagged = 0; + struct radix_tree_iter iter; + void **slot; + + spin_lock_irq(&mapping->tree_lock); + radix_tree_for_each_tagged(slot, &mapping->page_tree, &iter, start, + PAGECACHE_TAG_DIRTY) { + if (iter.index > end) + break; + radix_tree_iter_tag_set(&mapping->page_tree, &iter, + PAGECACHE_TAG_TOWRITE); + tagged++; + if ((tagged % WRITEBACK_TAG_BATCH) != 0) + continue; + slot = radix_tree_iter_resume(slot, &iter); spin_unlock_irq(&mapping->tree_lock); - WARN_ON_ONCE(tagged > WRITEBACK_TAG_BATCH); cond_resched(); - /* We check 'start' to handle wrapping when end == ~0UL */ - } while (tagged >= WRITEBACK_TAG_BATCH && start); + spin_lock_irq(&mapping->tree_lock); + } + spin_unlock_irq(&mapping->tree_lock); } EXPORT_SYMBOL(tag_pages_for_writeback); -- cgit v1.2.3