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From:   Sasha Levin <Alexander.Levin@microsoft.com>
To:     "stable@vger.kernel.org" <stable@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
CC:     NeilBrown <neilb@suse.com>,
        Trond Myklebust <trond.myklebust@primarydata.com>,
        Sasha Levin <Alexander.Levin@microsoft.com>
Subject: [PATCH AUTOSEL for 4.9 212/293] NFSv4: always set NFS_LOCK_LOST when
 a lock is lost.
Thread-Topic: [PATCH AUTOSEL for 4.9 212/293] NFSv4: always set NFS_LOCK_LOST
 when a lock is lost.
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Date:   Mon, 9 Apr 2018 00:25:39 +0000
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From: NeilBrown <neilb@suse.com>

[ Upstream commit dce2630c7da73b0634686bca557cc8945cc450c8 ]

There are 2 comments in the NFSv4 code which suggest that
SIGLOST should possibly be sent to a process.  In these
cases a lock has been lost.
The current practice is to set NFS_LOCK_LOST so that
read/write returns EIO when a lock is lost.
So change these comments to code when sets NFS_LOCK_LOST.

One case is when lock recovery after apparent server restart
fails with NFS4ERR_DENIED, NFS4ERR_RECLAIM_BAD, or
NFS4ERRO_RECLAIM_CONFLICT.  The other case is when a lock
attempt as part of lease recovery fails with NFS4ERR_DENIED.

In an ideal world, these should not happen.  However I have
a packet trace showing an NFSv4.1 session getting
NFS4ERR_BADSESSION after an extended network parition.  The
NFSv4.1 client treats this like server reboot until/unless
it get NFS4ERR_NO_GRACE, in which case it switches over to
"nograce" recovery mode.  In this network trace, the client
attempts to recover a lock and the server (incorrectly)
reports NFS4ERR_DENIED rather than NFS4ERR_NO_GRACE.  This
leads to the ineffective comment and the client then
continues to write using the OPEN stateid.

Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
 fs/nfs/nfs4proc.c  | 12 ++++++++----
 fs/nfs/nfs4state.c |  5 ++++-
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 4638654e26f3..883662d25714 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -1934,7 +1934,7 @@ static int nfs4_open_reclaim(struct nfs4_state_owner =
*sp, struct nfs4_state *sta
 	return ret;
 }
=20
-static int nfs4_handle_delegation_recall_error(struct nfs_server *server, =
struct nfs4_state *state, const nfs4_stateid *stateid, int err)
+static int nfs4_handle_delegation_recall_error(struct nfs_server *server, =
struct nfs4_state *state, const nfs4_stateid *stateid, struct file_lock *fl=
, int err)
 {
 	switch (err) {
 		default:
@@ -1981,7 +1981,11 @@ static int nfs4_handle_delegation_recall_error(struc=
t nfs_server *server, struct
 			return -EAGAIN;
 		case -ENOMEM:
 		case -NFS4ERR_DENIED:
-			/* kill_proc(fl->fl_pid, SIGLOST, 1); */
+			if (fl) {
+				struct nfs4_lock_state *lsp =3D fl->fl_u.nfs4_fl.owner;
+				if (lsp)
+					set_bit(NFS_LOCK_LOST, &lsp->ls_flags);
+			}
 			return 0;
 	}
 	return err;
@@ -2017,7 +2021,7 @@ int nfs4_open_delegation_recall(struct nfs_open_conte=
xt *ctx,
 		err =3D nfs4_open_recover_helper(opendata, FMODE_READ);
 	}
 	nfs4_opendata_put(opendata);
-	return nfs4_handle_delegation_recall_error(server, state, stateid, err);
+	return nfs4_handle_delegation_recall_error(server, state, stateid, NULL, =
err);
 }
=20
 static void nfs4_open_confirm_prepare(struct rpc_task *task, void *calldat=
a)
@@ -6493,7 +6497,7 @@ int nfs4_lock_delegation_recall(struct file_lock *fl,=
 struct nfs4_state *state,
 	if (err !=3D 0)
 		return err;
 	err =3D _nfs4_do_setlk(state, F_SETLK, fl, NFS_LOCK_NEW);
-	return nfs4_handle_delegation_recall_error(server, state, stateid, err);
+	return nfs4_handle_delegation_recall_error(server, state, stateid, fl, er=
r);
 }
=20
 struct nfs_release_lockowner_data {
diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index 71deeae6eefd..cfd1222ef303 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -1429,6 +1429,7 @@ static int nfs4_reclaim_locks(struct nfs4_state *stat=
e, const struct nfs4_state_
 	struct inode *inode =3D state->inode;
 	struct nfs_inode *nfsi =3D NFS_I(inode);
 	struct file_lock *fl;
+	struct nfs4_lock_state *lsp;
 	int status =3D 0;
 	struct file_lock_context *flctx =3D inode->i_flctx;
 	struct list_head *list;
@@ -1469,7 +1470,9 @@ restart:
 		case -NFS4ERR_DENIED:
 		case -NFS4ERR_RECLAIM_BAD:
 		case -NFS4ERR_RECLAIM_CONFLICT:
-			/* kill_proc(fl->fl_pid, SIGLOST, 1); */
+			lsp =3D fl->fl_u.nfs4_fl.owner;
+			if (lsp)
+				set_bit(NFS_LOCK_LOST, &lsp->ls_flags);
 			status =3D 0;
 		}
 		spin_lock(&flctx->flc_lock);
--=20
2.15.1