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Commit 14fb9c9e authored by Jeff Layton's avatar Jeff Layton Committed by Ilya Dryomov
Browse files

ceph: allow dentry_lease_is_valid to work under RCU walk 



Under rcuwalk, we need to take extra care when dereferencing d_parent.
We want to do that once and pass a pointer to dentry_lease_is_valid.

Also, we must ensure that that function can handle the case where we're
racing with d_release. Check whether "di" is NULL under the d_lock, and
just return 0 if so.

Finally, we still need to kick off a renewal job if the lease is getting
close to expiration. If that's the case, then just drop out of rcuwalk
mode since that could block.

Signed-off-by: default avatarJeff Layton <jlayton@redhat.com>
Reviewed-by: default avatarYan, Zheng <zyan@redhat.com>
parent 5b484a51

fs/ceph/dir.c

+26 −15
Original line number Diff line number Diff line
@@ -1133,7 +1133,8 @@ void ceph_invalidate_dentry_lease(struct dentry *dentry) 
 * Check if dentry lease is valid.  If not, delete the lease.  Try to

 * renew if the least is more than half up.

 */

static int dentry_lease_is_valid(struct dentry *dentry)

static int dentry_lease_is_valid(struct dentry *dentry, unsigned int flags,

				 struct inode *dir)

{

	struct ceph_dentry_info *di;

	struct ceph_mds_session *s;
@@ -1141,12 +1142,11 @@ static int dentry_lease_is_valid(struct dentry *dentry) 
	u32 gen;

	unsigned long ttl;

	struct ceph_mds_session *session = NULL;

	struct inode *dir = NULL;

	u32 seq = 0;



	spin_lock(&dentry->d_lock);

	di = ceph_dentry(dentry);

	if (di->lease_session) {

	if (di && di->lease_session) {

		s = di->lease_session;

		spin_lock(&s->s_gen_ttl_lock);

		gen = s->s_cap_gen;
@@ -1159,8 +1159,14 @@ static int dentry_lease_is_valid(struct dentry *dentry) 
			valid = 1;

			if (di->lease_renew_after &&

			    time_after(jiffies, di->lease_renew_after)) {

				/* we should renew */

				dir = d_inode(dentry->d_parent);

				/*

				 * We should renew. If we're in RCU walk mode

				 * though, we can't do that so just return

				 * -ECHILD.

				 */

				if (flags & LOOKUP_RCU) {

					valid = -ECHILD;

				} else {

					session = ceph_get_mds_session(s);

					seq = di->lease_seq;

					di->lease_renew_after = 0;
@@ -1168,6 +1174,7 @@ static int dentry_lease_is_valid(struct dentry *dentry) 
				}

			}

		}

	}

	spin_unlock(&dentry->d_lock);



	if (session) {
@@ -1224,13 +1231,17 @@ static int ceph_d_revalidate(struct dentry *dentry, unsigned int flags) 
	} else if (d_really_is_positive(dentry) &&

		   ceph_snap(d_inode(dentry)) == CEPH_SNAPDIR) {

		valid = 1;

	} else if (dentry_lease_is_valid(dentry) ||

		   dir_lease_is_valid(dir, dentry)) {

	} else {

		valid = dentry_lease_is_valid(dentry, flags, dir);

		if (valid == -ECHILD)

			return valid;

		if (valid || dir_lease_is_valid(dir, dentry)) {

			if (d_really_is_positive(dentry))

				valid = ceph_is_any_caps(d_inode(dentry));

			else

				valid = 1;

		}

	}



	if (!valid) {

		struct ceph_mds_client *mdsc =