From: Trond Myklebust <trond.myklebust@primarydata.com>
Date: Thu, 1 Oct 2015 22:38:27 +0000 (-0400)
Subject: NFS: Fix a write performance regression
X-Git-Tag: submit/tizen/20160607.132125~1643^2~6
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=8fa4592a14ebb3c22a21d846d1e4f65dab7d1a7c;p=sdk%2Femulator%2Femulator-kernel.git

NFS: Fix a write performance regression

If all other conditions in nfs_can_extend_write() are met, and there
are no locks, then we should be able to assume close-to-open semantics
and the ability to extend our write to cover the whole page.

With this patch, the xfstests generic/074 test completes in 242s instead
of >1400s on my test rig.

Fixes: bd61e0a9c852 ("locks: convert posix locks to file_lock_context")
Cc: Jeff Layton <jlayton@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
---

diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index cfa4776..75ab762 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -1223,7 +1223,7 @@ static int nfs_can_extend_write(struct file *file, struct page *page, struct ino
 		return 1;
 	if (!flctx || (list_empty_careful(&flctx->flc_flock) &&
 		       list_empty_careful(&flctx->flc_posix)))
-		return 0;
+		return 1;
 
 	/* Check to see if there are whole file write locks */
 	ret = 0;