ceph: don't clear I_NEW until inode metadata is fully populated

Currently, we could have an open-by-handle (or NFS server) call
into the filesystem and start working with an inode before it's
properly filled out.

Don't clear I_NEW until we have filled out the inode, and discard it
properly if that fails. Note that we occasionally take an extra
reference to the inode to ensure that we don't put the last reference in
discard_new_inode, but rather leave it for ceph_async_iput.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/ceph/inode.c

@@ -55,11 +55,9 @@ struct inode *ceph_get_inode(struct super_block *sb, struct ceph_vino vino)
 	inode = iget5_locked(sb, t, ceph_ino_compare, ceph_set_ino_cb, &vino);
 	if (!inode)
 		return ERR_PTR(-ENOMEM);
-	if (inode->i_state & I_NEW) {
+	if (inode->i_state & I_NEW)
 		dout("get_inode created new inode %p %llx.%llx ino %llx\n",
 		     inode, ceph_vinop(inode), (u64)inode->i_ino);
-		unlock_new_inode(inode);
-	}
 
 	dout("get_inode on %lu=%llx.%llx got %p\n", inode->i_ino, vino.ino,
 	     vino.snap, inode);
@@ -88,6 +86,10 @@ struct inode *ceph_get_snapdir(struct inode *parent)
 	inode->i_fop = &ceph_snapdir_fops;
 	ci->i_snap_caps = CEPH_CAP_PIN; /* so we can open */
 	ci->i_rbytes = 0;
+
+	if (inode->i_state & I_NEW)
+		unlock_new_inode(inode);
+
 	return inode;
 }
 
@@ -1304,7 +1306,6 @@ int ceph_fill_trace(struct super_block *sb, struct ceph_mds_request *req)
 			err = PTR_ERR(in);
 			goto done;
 		}
-		req->r_target_inode = in;
 
 		err = fill_inode(in, req->r_locked_page, &rinfo->targeti, NULL,
 				session,
@@ -1314,8 +1315,13 @@ int ceph_fill_trace(struct super_block *sb, struct ceph_mds_request *req)
 		if (err < 0) {
 			pr_err("fill_inode badness %p %llx.%llx\n",
 				in, ceph_vinop(in));
+			if (in->i_state & I_NEW)
+				discard_new_inode(in);
 			goto done;
 		}
+		req->r_target_inode = in;
+		if (in->i_state & I_NEW)
+			unlock_new_inode(in);
 	}
 
 	/*
@@ -1499,7 +1505,14 @@ static int readdir_prepopulate_inodes_only(struct ceph_mds_request *req,
 		if (rc < 0) {
 			pr_err("fill_inode badness on %p got %d\n", in, rc);
 			err = rc;
+			if (in->i_state & I_NEW) {
+				ihold(in);
+				discard_new_inode(in);
+			}
+		} else if (in->i_state & I_NEW) {
+			unlock_new_inode(in);
 		}
+
 		/* avoid calling iput_final() in mds dispatch threads */
 		ceph_async_iput(in);
 	}
@@ -1701,12 +1714,18 @@ int ceph_readdir_prepopulate(struct ceph_mds_request *req,
 			if (d_really_is_negative(dn)) {
 				/* avoid calling iput_final() in mds
 				 * dispatch threads */
+				if (in->i_state & I_NEW) {
+					ihold(in);
+					discard_new_inode(in);
+				}
 				ceph_async_iput(in);
 			}
 			d_drop(dn);
 			err = ret;
 			goto next_item;
 		}
+		if (in->i_state & I_NEW)
+			unlock_new_inode(in);
 
 		if (d_really_is_negative(dn)) {
 			if (ceph_security_xattr_deadlock(in)) {