From: Jinshan Xiong <jinshan.xiong@intel.com>
Date: Thu, 10 Apr 2014 15:40:49 +0000 (-0400)
Subject: LU-4873 llite: avoid a deadlock in page write
X-Git-Tag: 2.5.58~23
X-Git-Url: https://git.whamcloud.com/?a=commitdiff_plain;h=50eeb38a8c1ca26c5837149aa442288af8d4fc45;p=fs%2Flustre-release.git

LU-4873 llite: avoid a deadlock in page write

For a partial page write, it will have to issue a READ RPC firstly
to get a full uptodate page. If another page is already locked by
this thread it can easily cause deadlock.

Signed-off-by: Jinshan Xiong <jinshan.xiong@intel.com>
Change-Id: I3bf01b51c8842666dfb923b9df073acbcc533950
Reviewed-on: http://review.whamcloud.com/9928
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Bobi Jam <bobijam@gmail.com>
Reviewed-by: Niu Yawei <yawei.niu@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
---

diff --git a/lustre/llite/rw26.c b/lustre/llite/rw26.c
index 77151de..64a06f9 100644
--- a/lustre/llite/rw26.c
+++ b/lustre/llite/rw26.c
@@ -554,8 +554,9 @@ static int ll_write_begin(struct file *file, struct address_space *mapping,
 	env = lcc->lcc_env;
 	io  = lcc->lcc_io;
 
-	/* To avoid deadlock, try to lock page first. */
-	vmpage = grab_cache_page_nowait(mapping, index);
+	if (likely(to == PAGE_SIZE)) /* LU-4873 */
+		/* To avoid deadlock, try to lock page first. */
+		vmpage = grab_cache_page_nowait(mapping, index);
 	if (unlikely(vmpage == NULL ||
 		     PageDirty(vmpage) || PageWriteback(vmpage))) {
 		struct ccc_io *cio = ccc_env_io(env);