From: Trond Myklebust <trond.myklebust@primarydata.com>
Date: Fri, 18 Nov 2016 20:21:30 +0000 (-0500)
Subject: pNFS: Fix race in pnfs_wait_on_layoutreturn
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=4c4d4bec6c904fc050847f977b13052be5745ae1;p=linux-beck.git

pNFS: Fix race in pnfs_wait_on_layoutreturn

commit ee284e35d8c71bf5d4d807eaff6f67a17134b359 upstream.

We must put the task to sleep while holding the inode->i_lock in order
to ensure atomicity with the test for NFS_LAYOUT_RETURN.

Fixes: 500d701f336b ("NFS41: make close wait for layoutreturn")
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index 31b107e196fd..415d7e69bc5e 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -1257,13 +1257,11 @@ bool pnfs_wait_on_layoutreturn(struct inode *ino, struct rpc_task *task)
 	 * i_lock */
         spin_lock(&ino->i_lock);
         lo = nfsi->layout;
-        if (lo && test_bit(NFS_LAYOUT_RETURN, &lo->plh_flags))
+        if (lo && test_bit(NFS_LAYOUT_RETURN, &lo->plh_flags)) {
+                rpc_sleep_on(&NFS_SERVER(ino)->roc_rpcwaitq, task, NULL);
                 sleep = true;
+	}
         spin_unlock(&ino->i_lock);
-
-        if (sleep)
-                rpc_sleep_on(&NFS_SERVER(ino)->roc_rpcwaitq, task, NULL);
-
         return sleep;
 }