linux-kernel - [PATCH AUTOSEL 5.12 24/37] ceph: don't clobber i_snap_caps on non-I

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Date:   Wed, 12 May 2021 14:00:51 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Jeff Layton <jlayton@...nel.org>,
        Al Viro <viro@...iv.linux.org.uk>,
        Ilya Dryomov <idryomov@...il.com>,
        Sasha Levin <sashal@...nel.org>, ceph-devel@...r.kernel.org
Subject: [PATCH AUTOSEL 5.12 24/37] ceph: don't clobber i_snap_caps on non-I_NEW inode

From: Jeff Layton <jlayton@...nel.org>

[ Upstream commit d3c51ae1b8cce5bdaf91a1ce32b33cf5626075dc ]

We want the snapdir to mirror the non-snapped directory's attributes for
most things, but i_snap_caps represents the caps granted on the snapshot
directory by the MDS itself. A misbehaving MDS could issue different
caps for the snapdir and we lose them here.

Only reset i_snap_caps when the inode is I_NEW. Also, move the setting
of i_op and i_fop inside the if block since they should never change
anyway.

Reported-by: Al Viro <viro@...iv.linux.org.uk>
Signed-off-by: Jeff Layton <jlayton@...nel.org>
Signed-off-by: Ilya Dryomov <idryomov@...il.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/ceph/inode.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index 4418d4be2907..2fd1c48ac5d7 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -87,14 +87,15 @@ struct inode *ceph_get_snapdir(struct inode *parent)
 	inode->i_mtime = parent->i_mtime;
 	inode->i_ctime = parent->i_ctime;
 	inode->i_atime = parent->i_atime;
-	inode->i_op = &ceph_snapdir_iops;
-	inode->i_fop = &ceph_snapdir_fops;
-	ci->i_snap_caps = CEPH_CAP_PIN; /* so we can open */
 	ci->i_rbytes = 0;
 	ci->i_btime = ceph_inode(parent)->i_btime;
 
-	if (inode->i_state & I_NEW)
+	if (inode->i_state & I_NEW) {
+		inode->i_op = &ceph_snapdir_iops;
+		inode->i_fop = &ceph_snapdir_fops;
+		ci->i_snap_caps = CEPH_CAP_PIN; /* so we can open */
 		unlock_new_inode(inode);
+	}
 
 	return inode;
 }
-- 
2.30.2