ceph: use lookup request to revalidate dentry

If dentry has no lease, ceph_d_revalidate() previously return 0.
This causes VFS to invalidate the dentry and create a new dentry
for later lookup. Invalidating a dentry also detach any underneath
mount points. So mount point inside cephfs can disapear mystically
(even the mount point is not modified by other hosts).

The fix is using lookup request to revalidate dentry without lease.
This can partly solve the mount points disapear issue (as long as
the mount point is not modified by other hosts)

Signed-off-by: Yan, Zheng <zyan@redhat.com>

1 files changed, 34 insertions, 0 deletions

diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index c37820bcb66b..d6c13f9c9317 100644
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -1111,6 +1111,40 @@ static int ceph_d_revalidate(struct dentry *dentry, unsigned int flags)
 			valid = 1;
 	}
 
+	if (!valid) {
+		struct ceph_mds_client *mdsc =
+			ceph_sb_to_client(dir->i_sb)->mdsc;
+		struct ceph_mds_request *req;
+		int op, mask, err;
+
+		op = ceph_snap(dir) == CEPH_SNAPDIR ?
+			CEPH_MDS_OP_LOOKUPSNAP : CEPH_MDS_OP_LOOKUP;
+		req = ceph_mdsc_create_request(mdsc, op, USE_ANY_MDS);
+		if (!IS_ERR(req)) {
+			req->r_dentry = dget(dentry);
+			req->r_num_caps = 2;
+
+			mask = CEPH_STAT_CAP_INODE | CEPH_CAP_AUTH_SHARED;
+			if (ceph_security_xattr_wanted(dir))
+				mask |= CEPH_CAP_XATTR_SHARED;
+			req->r_args.getattr.mask = mask;
+
+			req->r_locked_dir = dir;
+			err = ceph_mdsc_do_request(mdsc, NULL, req);
+			if (err == 0 || err == -ENOENT) {
+				if (dentry == req->r_dentry) {
+					valid = !d_unhashed(dentry);
+				} else {
+					d_invalidate(req->r_dentry);
+					err = -EAGAIN;
+				}
+			}
+			ceph_mdsc_put_request(req);
+			dout("d_revalidate %p lookup result=%d\n",
+			     dentry, err);
+		}
+	}
+
 	dout("d_revalidate %p %s\n", dentry, valid ? "valid" : "invalid");
 	if (valid) {
 		ceph_dentry_lru_touch(dentry);