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Commit d3383a8e authored by Yan, Zheng's avatar Yan, Zheng Committed by Ilya Dryomov
Browse files

ceph: avoid block operation when !TASK_RUNNING (ceph_mdsc_sync) 



check_cap_flush() calls mutex_lock(), which may block. So we can't
use it as condition check function for wait_event();

Signed-off-by: default avatarYan, Zheng <zyan@redhat.com>
parent 73e39e4d

fs/ceph/caps.c

+1 −1
Original line number Diff line number Diff line
@@ -1450,8 +1450,8 @@ static int __mark_caps_flushing(struct inode *inode, 
	spin_lock(&mdsc->cap_dirty_lock);

	list_del_init(&ci->i_dirty_item);



	ci->i_cap_flush_seq = ++mdsc->cap_flush_seq;

	if (list_empty(&ci->i_flushing_item)) {

		ci->i_cap_flush_seq = ++mdsc->cap_flush_seq;

		list_add_tail(&ci->i_flushing_item, &session->s_cap_flushing);

		mdsc->num_cap_flushing++;

		dout(" inode %p now flushing seq %lld\n", inode,

fs/ceph/mds_client.c

+34 −17
Original line number Diff line number Diff line
@@ -1464,19 +1464,33 @@ int ceph_add_cap_releases(struct ceph_mds_client *mdsc, 
	return err;

}



static int check_cap_flush(struct inode *inode, u64 want_flush_seq)

{

	struct ceph_inode_info *ci = ceph_inode(inode);

	int ret;

	spin_lock(&ci->i_ceph_lock);

	if (ci->i_flushing_caps)

		ret = ci->i_cap_flush_seq >= want_flush_seq;

	else

		ret = 1;

	spin_unlock(&ci->i_ceph_lock);

	return ret;

}



/*

 * flush all dirty inode data to disk.

 *

 * returns true if we've flushed through want_flush_seq

 */

static int check_cap_flush(struct ceph_mds_client *mdsc, u64 want_flush_seq)

static void wait_caps_flush(struct ceph_mds_client *mdsc, u64 want_flush_seq)

{

	int mds, ret = 1;

	int mds;



	dout("check_cap_flush want %lld\n", want_flush_seq);

	mutex_lock(&mdsc->mutex);

	for (mds = 0; ret && mds < mdsc->max_sessions; mds++) {

	for (mds = 0; mds < mdsc->max_sessions; mds++) {

		struct ceph_mds_session *session = mdsc->sessions[mds];

		struct inode *inode = NULL;



		if (!session)

			continue;
@@ -1489,29 +1503,29 @@ static int check_cap_flush(struct ceph_mds_client *mdsc, u64 want_flush_seq) 
				list_entry(session->s_cap_flushing.next,

					   struct ceph_inode_info,

					   i_flushing_item);

			struct inode *inode = &ci->vfs_inode;



			spin_lock(&ci->i_ceph_lock);

			if (ci->i_cap_flush_seq <= want_flush_seq) {

			if (!check_cap_flush(&ci->vfs_inode, want_flush_seq)) {

				dout("check_cap_flush still flushing %p "

				     "seq %lld <= %lld to mds%d\n", inode,

				     ci->i_cap_flush_seq, want_flush_seq,

				     session->s_mds);

				ret = 0;

				     "seq %lld <= %lld to mds%d\n",

				     &ci->vfs_inode, ci->i_cap_flush_seq,

				     want_flush_seq, session->s_mds);

				inode = igrab(&ci->vfs_inode);

			}

			spin_unlock(&ci->i_ceph_lock);

		}

		mutex_unlock(&session->s_mutex);

		ceph_put_mds_session(session);



		if (!ret)

			return ret;

		if (inode) {

			wait_event(mdsc->cap_flushing_wq,

				   check_cap_flush(inode, want_flush_seq));

			iput(inode);

		}



		mutex_lock(&mdsc->mutex);

	}



	mutex_unlock(&mdsc->mutex);

	dout("check_cap_flush ok, flushed thru %lld\n", want_flush_seq);

	return ret;

}



/*
@@ -3447,14 +3461,17 @@ void ceph_mdsc_sync(struct ceph_mds_client *mdsc) 
	dout("sync\n");

	mutex_lock(&mdsc->mutex);

	want_tid = mdsc->last_tid;

	want_flush = mdsc->cap_flush_seq;

	mutex_unlock(&mdsc->mutex);

	dout("sync want tid %lld flush_seq %lld\n", want_tid, want_flush);



	ceph_flush_dirty_caps(mdsc);

	spin_lock(&mdsc->cap_dirty_lock);

	want_flush = mdsc->cap_flush_seq;

	spin_unlock(&mdsc->cap_dirty_lock);



	dout("sync want tid %lld flush_seq %lld\n", want_tid, want_flush);



	wait_unsafe_requests(mdsc, want_tid);

	wait_event(mdsc->cap_flushing_wq, check_cap_flush(mdsc, want_flush));

	wait_caps_flush(mdsc, want_flush);

}



/*