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Commit ff513ace authored by Ilya Dryomov's avatar Ilya Dryomov Committed by Sage Weil
Browse files

libceph: take map_sem for read in handle_reply() 



Handling redirect replies requires both map_sem and request_mutex.
Taking map_sem unconditionally near the top of handle_reply() avoids
possible race conditions that arise from releasing request_mutex to be
able to acquire map_sem in redirect reply case.  (Lock ordering is:
map_sem, request_mutex, crush_mutex.)

Signed-off-by: default avatarIlya Dryomov <ilya.dryomov@inktank.com>
Reviewed-by: default avatarSage Weil <sage@inktank.com>
parent 0bbfdfe8

net/ceph/osd_client.c

+11 −6
Original line number Diff line number Diff line
@@ -1687,6 +1687,7 @@ static void handle_reply(struct ceph_osd_client *osdc, struct ceph_msg *msg, 
	osdmap_epoch = ceph_decode_32(&p);



	/* lookup */

	down_read(&osdc->map_sem);

	mutex_lock(&osdc->request_mutex);

	req = __lookup_request(osdc, tid);

	if (req == NULL) {
@@ -1743,7 +1744,6 @@ static void handle_reply(struct ceph_osd_client *osdc, struct ceph_msg *msg, 
		dout("redirect pool %lld\n", redir.oloc.pool);



		__unregister_request(osdc, req);

		mutex_unlock(&osdc->request_mutex);



		req->r_target_oloc = redir.oloc; /* struct */
@@ -1755,10 +1755,10 @@ static void handle_reply(struct ceph_osd_client *osdc, struct ceph_msg *msg, 
		 * successfully.  In the future we might want to follow

		 * original request's nofail setting here.

		 */

		err = ceph_osdc_start_request(osdc, req, true);

		err = __ceph_osdc_start_request(osdc, req, true);

		BUG_ON(err);



		goto done;

		goto out_unlock;

	}



	already_completed = req->r_got_reply;
@@ -1776,8 +1776,7 @@ static void handle_reply(struct ceph_osd_client *osdc, struct ceph_msg *msg, 
		req->r_got_reply = 1;

	} else if ((flags & CEPH_OSD_FLAG_ONDISK) == 0) {

		dout("handle_reply tid %llu dup ack\n", tid);

		mutex_unlock(&osdc->request_mutex);

		goto done;

		goto out_unlock;

	}



	dout("handle_reply tid %llu flags %d\n", tid, flags);
@@ -1792,6 +1791,7 @@ static void handle_reply(struct ceph_osd_client *osdc, struct ceph_msg *msg, 
		__unregister_request(osdc, req);



	mutex_unlock(&osdc->request_mutex);

	up_read(&osdc->map_sem);



	if (!already_completed) {

		if (req->r_unsafe_callback &&
@@ -1809,10 +1809,14 @@ static void handle_reply(struct ceph_osd_client *osdc, struct ceph_msg *msg, 
		complete_request(req);

	}



done:

out:

	dout("req=%p req->r_linger=%d\n", req, req->r_linger);

	ceph_osdc_put_request(req);

	return;

out_unlock:

	mutex_unlock(&osdc->request_mutex);

	up_read(&osdc->map_sem);

	goto out;



bad_put:

	req->r_result = -EIO;
@@ -1825,6 +1829,7 @@ bad_put: 
	ceph_osdc_put_request(req);

bad_mutex:

	mutex_unlock(&osdc->request_mutex);

	up_read(&osdc->map_sem);

bad:

	pr_err("corrupt osd_op_reply got %d %d\n",

	       (int)msg->front.iov_len, le32_to_cpu(msg->hdr.front_len));