extension of IncrementalRemove to store location (path-id) of removed device

If the disk is taken out from its port this port information is
lost. Only udev rule can provide us with this information, and then we
have to store it somehow. This patch adds writing 'cookie' file in
/dev/.mdadm/failed-slots directory in form of file named with value of
f<path-id> containing the metadata type and uuid of the array (or
container) that the device was a member of.  The uuid is in exactly
the same format as in the mapfile.

FAILED_SLOTS_DIR constant has been added to hold the location of
cookie files.

Signed-off-by: Przemyslaw Czarnowski <przemyslaw.hawrylewicz.czarnowski@intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>

1 files changed, 67 insertions, 0 deletions

diff --git a/policy.c b/policy.c
index 0bc3c452..28751fb9 100644
--- a/policy.c
+++ b/policy.c
@@ -644,3 +644,70 @@ void domain_free(struct domainlist *dl)
 		free(head);
 	}
 }
+
+/*
+ * same-path policy.
+ * Some policy decisions are guided by knowledge of which
+ * array previously owned the device at a given physical location (path).
+ * When removing a device from an array we might record the array against
+ * the path, and when finding a new device, we might look for which
+ * array previously used that path.
+ *
+ * The 'array' is described by a map_ent, and the path by a the disk in an
+ * mdinfo, or a string.
+ */
+
+void policy_save_path(char *id_path, struct map_ent *array)
+{
+	char path[PATH_MAX];
+	FILE *f = NULL;
+
+	if (mkdir(FAILED_SLOTS_DIR, S_IRWXU) < 0 && errno != EEXIST) {
+		fprintf(stderr, Name ": can't create file to save path "
+			"to old disk: %s\n", strerror(errno));
+		return;
+	}
+
+	snprintf(path, PATH_MAX, FAILED_SLOTS_DIR "/%s", id_path);
+	f = fopen(path, "w");
+	if (!f) {
+		fprintf(stderr, Name ": can't create file to"
+			" save path to old disk: %s\n",
+			strerror(errno));
+		return;
+	}
+
+	if (fprintf(f, "%s %08x:%08x:%08x:%08x\n",
+		    array->metadata,
+		    array->uuid[0], array->uuid[1],
+		    array->uuid[2], array->uuid[3]) <= 0)
+		fprintf(stderr, Name ": Failed to write to "
+			"<id_path> cookie\n");
+
+	fclose(f);
+}
+
+int policy_check_path(struct mdinfo *disk, struct map_ent *array)
+{
+	char path[PATH_MAX];
+	FILE *f = NULL;
+	char *id_path = disk_path(disk);
+	int rv;
+
+	if (!id_path)
+		return 0;
+
+	snprintf(path, PATH_MAX, FAILED_SLOTS_DIR "/%s", id_path);
+	f = fopen(path, "r");
+	if (!f)
+		return 0;
+
+	rv = fscanf(f, " %s %x:%x:%x:%x\n",
+		    array->metadata,
+		    array->uuid,
+		    array->uuid+1,
+		    array->uuid+2,
+		    array->uuid+3);
+	fclose(f);
+	return rv == 5;
+}