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authorMatthew Wilcox <mawilcox@microsoft.com>2016-12-14 15:08:55 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2016-12-14 16:04:10 -0800
commit268f42de718128cd0301293177e79c08c38e39a6 (patch)
tree6668c85388c327f64ce9b51e77d70e245ec52b57 /mm
parentradix-tree: delete radix_tree_locate_item() (diff)
downloadwireguard-linux-268f42de718128cd0301293177e79c08c38e39a6.tar.xz
wireguard-linux-268f42de718128cd0301293177e79c08c38e39a6.zip
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>
Diffstat (limited to 'mm')
-rw-r--r--mm/page-writeback.c28
1 files changed, 18 insertions, 10 deletions
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);