Commit b4556396 authored by Sage Weil's avatar Sage Weil
Browse files

ceph: fix race between aborted requests and fill_trace 



When we abort requests we need to prevent fill_trace et al from doing
anything that relies on locks held by the VFS caller.  This fixes a race
between the reply handler and the abort code, ensuring that continue
holding the dir mutex until the reply handler completes.

Signed-off-by: default avatarSage Weil <sage@newdream.net>
parent e1518c7c

fs/ceph/mds_client.c

+11 −0
Original line number Diff line number Diff line
@@ -1181,6 +1181,7 @@ ceph_mdsc_create_request(struct ceph_mds_client *mdsc, int op, int mode) 
	if (!req)

		return ERR_PTR(-ENOMEM);



	mutex_init(&req->r_fill_mutex);

	req->r_started = jiffies;

	req->r_resend_mds = -1;

	INIT_LIST_HEAD(&req->r_unsafe_dir_item);
@@ -1715,8 +1716,16 @@ int ceph_mdsc_do_request(struct ceph_mds_client *mdsc, 
		err = le32_to_cpu(req->r_reply_info.head->result);

	} else if (err < 0) {

		dout("aborted request %lld with %d\n", req->r_tid, err);



		/*

		 * ensure we aren't running concurrently with

		 * ceph_fill_trace or ceph_readdir_prepopulate, which

		 * rely on locks (dir mutex) held by our caller.

		 */

		mutex_lock(&req->r_fill_mutex);

		req->r_err = err;

		req->r_aborted = true;

		mutex_unlock(&req->r_fill_mutex);



		if (req->r_locked_dir &&

		    (req->r_op & CEPH_MDS_OP_WRITE)) {
@@ -1861,12 +1870,14 @@ static void handle_reply(struct ceph_mds_session *session, struct ceph_msg *msg) 
	}



	/* insert trace into our cache */

	mutex_lock(&req->r_fill_mutex);

	err = ceph_fill_trace(mdsc->client->sb, req, req->r_session);

	if (err == 0) {

		if (result == 0 && rinfo->dir_nr)

			ceph_readdir_prepopulate(req, req->r_session);

		ceph_unreserve_caps(&req->r_caps_reservation);

	}

	mutex_unlock(&req->r_fill_mutex);



	up_read(&mdsc->snap_rwsem);

out_err:

fs/ceph/mds_client.h

+2 −0
Original line number Diff line number Diff line
@@ -165,6 +165,8 @@ struct ceph_mds_request { 
	struct inode *r_locked_dir; /* dir (if any) i_mutex locked by vfs */

	struct inode *r_target_inode;       /* resulting inode */



	struct mutex r_fill_mutex;



	union ceph_mds_request_args r_args;

	int r_fmode;        /* file mode, if expecting cap */

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