From: Trond Myklebust <Trond.Myklebust@netapp.com>
Date: Wed, 8 Aug 2012 20:03:13 +0000 (-0400)
Subject: NFSv4.1: Remove a bogus BUG_ON() in nfs4_layoutreturn_done
X-Git-Tag: firefly_0821_release~7541^2~761
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=4ad55ffb366e07fdaefc2372e77b98569c9b4619;p=firefly-linux-kernel-4.4.55.git

NFSv4.1: Remove a bogus BUG_ON() in nfs4_layoutreturn_done

commit 47fbf7976e0b7d9dcdd799e2a1baba19064d9631 upstream.

Ever since commit 0a57cdac3f (NFSv4.1 send layoutreturn to fence
disconnected data server) we've been sending layoutreturn calls
while there is potentially still outstanding I/O to the data
servers. The reason we do this is to avoid races between replayed
writes to the MDS and the original writes to the DS.

When this happens, the BUG_ON() in nfs4_layoutreturn_done can
be triggered because it assumes that we would never call
layoutreturn without knowing that all I/O to the DS is
finished. The fix is to remove the BUG_ON() now that the
assumptions behind the test are obsolete.

Reported-by: Boaz Harrosh <bharrosh@panasas.com>
Reported-by: Tigran Mkrtchyan <tigran.mkrtchyan@desy.de>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index b7a7e5fe4019..3da1166de197 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -5766,12 +5766,8 @@ static void nfs4_layoutreturn_done(struct rpc_task *task, void *calldata)
 		return;
 	}
 	spin_lock(&lo->plh_inode->i_lock);
-	if (task->tk_status == 0) {
-		if (lrp->res.lrs_present) {
-			pnfs_set_layout_stateid(lo, &lrp->res.stateid, true);
-		} else
-			BUG_ON(!list_empty(&lo->plh_segs));
-	}
+	if (task->tk_status == 0 && lrp->res.lrs_present)
+		pnfs_set_layout_stateid(lo, &lrp->res.stateid, true);
 	lo->plh_block_lgets--;
 	spin_unlock(&lo->plh_inode->i_lock);
 	dprintk("<-- %s\n", __func__);