From: Yan, Zheng zyan@redhat.com
[ Upstream commit 0aa971b6fd3f92afef6afe24ef78d9bb14471519 ]
1. try_get_cap_refs() fails to get caps and finds that mds_wanted does not include what it wants. It returns -ESTALE. 2. ceph_get_caps() calls ceph_renew_caps(). ceph_renew_caps() finds that inode has cap, so it calls ceph_check_caps(). 3. ceph_check_caps() finds that issued caps (without checking if it's stale) already includes caps wanted by open file, so it skips updating wanted caps.
Above events can cause an infinite loop inside ceph_get_caps().
Signed-off-by: "Yan, Zheng" zyan@redhat.com Reviewed-by: Jeff Layton jlayton@kernel.org Signed-off-by: Ilya Dryomov idryomov@gmail.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/ceph/caps.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c index 28ae0c1347004..d050acc1fd5d9 100644 --- a/fs/ceph/caps.c +++ b/fs/ceph/caps.c @@ -1973,8 +1973,12 @@ retry_locked: }
/* want more caps from mds? */ - if (want & ~(cap->mds_wanted | cap->issued)) - goto ack; + if (want & ~cap->mds_wanted) { + if (want & ~(cap->mds_wanted | cap->issued)) + goto ack; + if (!__cap_is_valid(cap)) + goto ack; + }
/* things we might delay */ if ((cap->issued & ~retain) == 0)