From: "Yan, Zheng" <zyan@redhat.com>
Date: Thu, 23 May 2019 11:01:37 +0800
Subject: ceph: hold i_ceph_lock when removing caps for freeing inode
Git-commit: d6e47819721ae2d9d090058ad5570a66f3c42e39
Patch-mainline: v5.3-rc1
References: bsc#1148133

ceph_d_revalidate(, LOOKUP_RCU) may call __ceph_caps_issued_mask()
on a freeing inode.

Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Acked-by: Luis Henriques <lhenriques@suse.com>
[luis: modified ceph_queue_caps_release() instead of __ceph_remove_caps,
 as in stable 4.14]
---
 fs/ceph/caps.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -1239,20 +1239,23 @@ static int send_cap_msg(struct cap_msg_a
 }
 
 /*
- * Queue cap releases when an inode is dropped from our cache.  Since
- * inode is about to be destroyed, there is no need for i_ceph_lock.
+ * Queue cap releases when an inode is dropped from our cache.
  */
 void ceph_queue_caps_release(struct inode *inode)
 {
 	struct ceph_inode_info *ci = ceph_inode(inode);
 	struct rb_node *p;
 
+	/* lock i_ceph_lock, because ceph_d_revalidate(..., LOOKUP_RCU)
+	 * may call __ceph_caps_issued_mask() on a freeing inode. */
+	spin_lock(&ci->i_ceph_lock);
 	p = rb_first(&ci->i_caps);
 	while (p) {
 		struct ceph_cap *cap = rb_entry(p, struct ceph_cap, ci_node);
 		p = rb_next(p);
 		__ceph_remove_cap(cap, true);
 	}
+	spin_unlock(&ci->i_ceph_lock);
 }
 
 /*