On Tue, Mar 6, 2018 at 6:25 PM, Chengguang Xu <cgxu519@xxxxxxx> wrote:
>> Sent: Tuesday, March 06, 2018 at 4:22 PM
>> From: "Yan, Zheng" <ukernel@xxxxxxxxx>
>> To: "Chengguang Xu" <cgxu519@xxxxxxxxxx>
>> Cc: "Yan, Zheng" <zyan@xxxxxxxxxx>, "Ceph Development" <ceph-devel@xxxxxxxxxxxxxxx>, "Ilya Dryomov" <idryomov@xxxxxxxxx>, cgxu519@xxxxxxx
>> Subject: Re: [PATCH] ceph: check return value of ceph_get_cap()
>>
>> On Tue, Mar 6, 2018 at 12:22 PM, Chengguang Xu <cgxu519@xxxxxxxxxx> wrote:
>> > Hi Yan,
>> >
>> > Any objection for this?
>> >
>>
>> Failing to record a cap from mds is serious problem. It may hang the
>> mds. I'd like to kill the whole mount in this case.
>
> How about calling panic() instead of working continuously?
>
null cap will trigger oops, that's enough.
>
>>
>> >> 在 2018年2月24日，下午6:34，Chengguang Xu <cgxu519@xxxxxxxxxx> 写道：
>> >>
>> >> ceph_get_cap() can return NULL, so should check return value carefully
>> >> in case of using NULL pointer unexpectedly.
>> >>
>> >> Signed-off-by: Chengguang Xu <cgxu519@xxxxxxxxxx>
>> >> ---
>> >> Only compile tested.
>> >>
>> >> fs/ceph/caps.c | 10 ++++++++++
>> >> 1 file changed, 10 insertions(+)
>> >>
>> >> diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
>> >> index 6582c45..9ef40ae 100644
>> >> --- a/fs/ceph/caps.c
>> >> +++ b/fs/ceph/caps.c
>> >> @@ -3510,6 +3510,10 @@ static void handle_cap_export(struct inode *inode, struct ceph_mds_caps *ex,
>> >> } else if (tsession) {
>> >> /* add placeholder for the export tagert */
>> >> int flag = (cap == ci->i_auth_cap) ? CEPH_CAP_FLAG_AUTH : 0;
>> >> +
>> >> + if (!new_cap)
>> >> + goto out_unlock;
>> >> +
>> >> tcap = new_cap;
>> >> ceph_add_cap(inode, tsession, t_cap_id, -1, issued, 0,
>> >> t_seq - 1, t_mseq, (u64)-1, flag, &new_cap);
>> >> @@ -3764,6 +3768,11 @@ void ceph_handle_caps(struct ceph_mds_session *session,
>> >>
>> >> if (op == CEPH_CAP_OP_IMPORT) {
>> >> cap = ceph_get_cap(mdsc, NULL);
>> >> + if (!cap) {
>> >> + pr_err("%s: can't get cap\n", __func__);
>> >> + goto bad_cap;
>> >> + }
>> >> +
>> >> cap->cap_ino = vino.ino;
>> >> cap->queue_release = 1;
>> >> cap->cap_id = le64_to_cpu(h->cap_id);
>> >> @@ -3864,6 +3873,7 @@ void ceph_handle_caps(struct ceph_mds_session *session,
>> >>
>> >> bad:
>> >> pr_err("ceph_handle_caps: corrupt message\n");
>> >> +bad_cap:
>> >> ceph_msg_dump(msg);
>> >> return;
>> >> }
>> >> --
>> >> 1.8.3.1
>> >>
>> >
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