[PATCH AUTOSEL 5.3 13/71] ceph: fetch cap_gen under spinlock in ceph_add_cap

Sasha Levin
2019-10-01T17:03:55Z

From: Jeff Layton <jlayton@kernel.org>

[ Upstream commit 606d102327a45a49d293557527802ee7fbfd7af1 ]

It's protected by the s_gen_ttl_lock, so we should fetch under it
and ensure that we're using the same generation in both places.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/ceph/caps.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index ce0f5658720ab..8fd5301128106 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -645,6 +645,7 @@ void ceph_add_cap(struct inode *inode,
struct ceph_cap *cap;
int mds = session->s_mds;
int actual_wanted;
+ u32 gen;

dout("add_cap %p mds%d cap %llx %s seq %d\n", inode,
session->s_mds, cap_id, ceph_cap_string(issued), seq);
@@ -656,6 +657,10 @@ void ceph_add_cap(struct inode *inode,
if (fmode >= 0)
wanted |= ceph_caps_for_mode(fmode);

+ spin_lock(&session->s_gen_ttl_lock);
+ gen = session->s_cap_gen;
+ spin_unlock(&session->s_gen_ttl_lock);
+
cap = __get_cap_for_mds(ci, mds);
if (!cap) {
cap = *new_cap;
@@ -681,7 +686,7 @@ void ceph_add_cap(struct inode *inode,
list_move_tail(&cap->session_caps, &session->s_caps);
spin_unlock(&session->s_cap_lock);

- if (cap->cap_gen < session->s_cap_gen)
+ if (cap->cap_gen < gen)
cap->issued = cap->implemented = CEPH_CAP_PIN;

/*
@@ -775,7 +780,7 @@ void ceph_add_cap(struct inode *inode,
cap->seq = seq;
cap->issue_seq = seq;
cap->mseq = mseq;
- cap->cap_gen = session->s_cap_gen;
+ cap->cap_gen = gen;

if (fmode >= 0)
__ceph_get_fmode(ci, fmode);
--
2.20.1