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 <[email protected]>
Acked-by: Konrad Rzeszutek Wilk <[email protected]>
---
 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

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