[PATCH 3/4] mm/truncate: bail out early from invalidate_inode_pages2_range() if mapping is empty

[Andrey Ryabinin]

If mapping is empty (both ->nrpages and ->nrexceptional is zero) we can avoid
pointless lookups in empty radix tree and bail out immediately after cleancache
invalidation.

Signed-off-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
---
 mm/truncate.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/truncate.c b/mm/truncate.c
index 6263aff..8f12b0e 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -624,6 +624,9 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
 	int did_range_unmap = 0;
 
 	cleancache_invalidate_inode(mapping);
+	if (mapping->nrpages == 0 && mapping->nrexceptional == 0)
+		return 0;
+
 	pagevec_init(&pvec, 0);
 	index = start;
 	while (index <= end && pagevec_lookup_entries(&pvec, mapping, index,
-- 
2.10.2