ceph: Check for created flag in response from mds

The mds now sends back a created inode if the create request
performed the create.  If the file already existed, no inode is
returned in the reply.  This allows ceph to set the created flag
in atomic_open so that permissions are properly checked in the case
that the file wasn't created by the create call to the mds.

To ensure compability with previous kernels, a feature for sending
back the inode in the create reply was added, so that the mds will
only send back the inode if the client indicates it supports the
feature.
Signed-off-by: Sam Lang <sam.lang@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>

fs/ceph/file.c

@@ -266,6 +266,9 @@ int ceph_atomic_open(struct inode *dir, struct dentry *dentry,
 		err = finish_no_open(file, dn);
 	} else {
 		dout("atomic_open finish_open on dn %p\n", dn);
+		if (req->r_op == CEPH_MDS_OP_CREATE && req->r_reply_info.has_create_ino) {
+			*opened |= FILE_CREATED;
+		}
 		err = finish_open(file, dentry, ceph_open, opened);
 	}
 

fs/ceph/mds_client.c

@@ -232,6 +232,30 @@ static int parse_reply_info_filelock(void **p, void *end,
 	return -EIO;
 }
 
+/*
+ * parse create results
+ */
+static int parse_reply_info_create(void **p, void *end,
+				  struct ceph_mds_reply_info_parsed *info,
+				  int features)
+{
+	if (features & CEPH_FEATURE_REPLY_CREATE_INODE) {
+		if (*p == end) {
+			info->has_create_ino = false;
+		} else {
+			info->has_create_ino = true;
+			info->ino = ceph_decode_64(p);
+		}
+	}
+
+	if (unlikely(*p != end))
+		goto bad;
+	return 0;
+
+bad:
+	return -EIO;
+}
+
 /*
  * parse extra results
  */
@@ -241,8 +265,12 @@ static int parse_reply_info_extra(void **p, void *end,
 {
 	if (info->head->op == CEPH_MDS_OP_GETFILELOCK)
 		return parse_reply_info_filelock(p, end, info, features);
-	else
+	else if (info->head->op == CEPH_MDS_OP_READDIR)
 		return parse_reply_info_dir(p, end, info, features);
+	else if (info->head->op == CEPH_MDS_OP_CREATE)
+		return parse_reply_info_create(p, end, info, features);
+	else
+		return -EIO;
 }
 
 /*
@@ -2170,7 +2198,8 @@ static void handle_reply(struct ceph_mds_session *session, struct ceph_msg *msg)
 	mutex_lock(&req->r_fill_mutex);
 	err = ceph_fill_trace(mdsc->fsc->sb, req, req->r_session);
 	if (err == 0) {
-		if (result == 0 && req->r_op != CEPH_MDS_OP_GETFILELOCK &&
+		if (result == 0 && (req->r_op == CEPH_MDS_OP_READDIR ||
+				    req->r_op == CEPH_MDS_OP_LSSNAP) &&
 		    rinfo->dir_nr)
 			ceph_readdir_prepopulate(req, req->r_session);
 		ceph_unreserve_caps(mdsc, &req->r_caps_reservation);

fs/ceph/mds_client.h

@@ -74,6 +74,12 @@ struct ceph_mds_reply_info_parsed {
 			struct ceph_mds_reply_info_in *dir_in;
 			u8                            dir_complete, dir_end;
 		};
+
+		/* for create results */
+		struct {
+			bool has_create_ino;
+			u64 ino;
+		};
 	};
 
 	/* encoded blob describing snapshot contexts for certain

include/linux/ceph/ceph_features.h

@@ -14,13 +14,16 @@
 #define CEPH_FEATURE_DIRLAYOUTHASH  (1<<7)
 /* bits 8-17 defined by user-space; not supported yet here */
 #define CEPH_FEATURE_CRUSH_TUNABLES (1<<18)
+/* bits 19-25 defined by user-space; not supported yet here */
+#define CEPH_FEATURE_REPLY_CREATE_INODE (1<<27)
 
 /*
  * Features supported.
  */
 #define CEPH_FEATURES_SUPPORTED_DEFAULT  \
 	(CEPH_FEATURE_NOSRCADDR |	 \
-	 CEPH_FEATURE_CRUSH_TUNABLES)
+	 CEPH_FEATURE_CRUSH_TUNABLES |   \
+	 CEPH_FEATURE_REPLY_CREATE_INODE)
 
 #define CEPH_FEATURES_REQUIRED_DEFAULT   \
 	(CEPH_FEATURE_NOSRCADDR)