[PATCH v2 3/4] mm/truncate: bail out early from invalidate_inode_pages2_range() if mapping is empty

From: Andrey Ryabinin <aryabinin@virtuozzo.com>
To: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	Ross Zwisler <ross.zwisler@linux.intel.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Jan Kara <jack@suse.cz>, Jens Axboe <axboe@kernel.dk>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Alexey Kuznetsov <kuznet@virtuozzo.com>,
	Christoph Hellwig <hch@lst.de>,
	Nikolay Borisov <n.borisov.lkml@gmail.com>,
	<linux-kernel@vger.kernel.org>, <linux-fsdevel@vger.kernel.org>,
	<linux-mm@kvack.org>
Subject: [PATCH v2 3/4] mm/truncate: bail out early from invalidate_inode_pages2_range() if mapping is empty
Date: Mon, 24 Apr 2017 19:41:34 +0300	[thread overview]
Message-ID: <20170424164135.22350-4-aryabinin@virtuozzo.com> (raw)
In-Reply-To: <20170424164135.22350-1-aryabinin@virtuozzo.com>

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@virtuozzo.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
 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
