From 4cd9973f9ff69e37dd0ba2bd6e6423f8179c329a Mon Sep 17 00:00:00 2001
From: Junxiao Bi <junxiao.bi@oracle.com>
Date: Thu, 25 Jun 2020 20:29:30 -0700
Subject: [PATCH 1/3] ocfs2: avoid inode removal while nfsd is accessing it
Git-commit: 4cd9973f9ff69e37dd0ba2bd6e6423f8179c329a
Patch-mainline: v5.8-rc3
References: bsc#1172963

Patch series "ocfs2: fix nfsd over ocfs2 issues", v2.

This is a series of patches to fix issues on nfsd over ocfs2.  patch 1
is to avoid inode removed while nfsd access it patch 2 & 3 is to fix a
panic issue.

This patch (of 3):

When nfsd is getting file dentry using handle or parent dentry of some
dentry, one cluster lock is used to avoid inode removed from other node,
but it still could be removed from local node, so use a rw lock to avoid
this.

Link: http://lkml.kernel.org/r/20200616183829.87211-1-junxiao.bi@oracle.com
Link: http://lkml.kernel.org/r/20200616183829.87211-2-junxiao.bi@oracle.com
Signed-off-by: Junxiao Bi <junxiao.bi@oracle.com>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Jun Piao <piaojun@huawei.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Gang He <ghe@suse.com>
---
 fs/ocfs2/dlmglue.c | 17 ++++++++++++++++-
 fs/ocfs2/ocfs2.h   |  1 +
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
index 6505611f2fbb..586b083e723e 100644
--- a/fs/ocfs2/dlmglue.c
+++ b/fs/ocfs2/dlmglue.c
@@ -701,6 +701,12 @@ static void ocfs2_nfs_sync_lock_res_init(struct ocfs2_lock_res *res,
 				   &ocfs2_nfs_sync_lops, osb);
 }
 
+static void ocfs2_nfs_sync_lock_init(struct ocfs2_super *osb)
+{
+	ocfs2_nfs_sync_lock_res_init(&osb->osb_nfs_sync_lockres, osb);
+	init_rwsem(&osb->nfs_sync_rwlock);
+}
+
 void ocfs2_trim_fs_lock_res_init(struct ocfs2_super *osb)
 {
 	struct ocfs2_lock_res *lockres = &osb->osb_trim_fs_lockres;
@@ -2785,6 +2791,11 @@ int ocfs2_nfs_sync_lock(struct ocfs2_super *osb, int ex)
 	if (ocfs2_is_hard_readonly(osb))
 		return -EROFS;
 
+	if (ex)
+		down_write(&osb->nfs_sync_rwlock);
+	else
+		down_read(&osb->nfs_sync_rwlock);
+
 	if (ocfs2_mount_local(osb))
 		return 0;
 
@@ -2803,6 +2814,10 @@ void ocfs2_nfs_sync_unlock(struct ocfs2_super *osb, int ex)
 	if (!ocfs2_mount_local(osb))
 		ocfs2_cluster_unlock(osb, lockres,
 				     ex ? LKM_EXMODE : LKM_PRMODE);
+	if (ex)
+		up_write(&osb->nfs_sync_rwlock);
+	else
+		up_read(&osb->nfs_sync_rwlock);
 }
 
 int ocfs2_trim_fs_lock(struct ocfs2_super *osb,
@@ -3300,7 +3315,7 @@ int ocfs2_dlm_init(struct ocfs2_super *osb)
 local:
 	ocfs2_super_lock_res_init(&osb->osb_super_lockres, osb);
 	ocfs2_rename_lock_res_init(&osb->osb_rename_lockres, osb);
-	ocfs2_nfs_sync_lock_res_init(&osb->osb_nfs_sync_lockres, osb);
+	ocfs2_nfs_sync_lock_init(osb);
 	ocfs2_orphan_scan_lock_res_init(&osb->osb_orphan_scan.os_lockres, osb);
 
 	osb->cconn = conn;
diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
index 1e9e24e83a6c..de5e8e8998fe 100644
--- a/fs/ocfs2/ocfs2.h
+++ b/fs/ocfs2/ocfs2.h
@@ -410,6 +410,7 @@ struct ocfs2_super
 	struct ocfs2_lock_res osb_super_lockres;
 	struct ocfs2_lock_res osb_rename_lockres;
 	struct ocfs2_lock_res osb_nfs_sync_lockres;
+	struct rw_semaphore nfs_sync_rwlock;
 	struct ocfs2_lock_res osb_trim_fs_lockres;
 	struct mutex obs_trim_fs_mutex;
 	struct ocfs2_dlm_debug *osb_dlm_debug;
-- 
2.21.0