Check if source device has been mounted

The filesystem we are restoring into needs to be empty
and never mounted. Here we check the all of the quorum blocks
timestamps to see whether the device we are restoring into has
been mounted before. Adds a test in the test script that attempts
to restore a previously mounted device.

Signed-off-by: Hunter Shaffer <hunter.shaffer@versity.com>
Signed-off-by: Auke Kok <auke.kok@versity.com>

tests/src/parallel_restore.c

@@ -601,7 +601,7 @@ static int do_restore(struct opts *opts)
 	ret = scoutfs_parallel_restore_create_writer(&wri);
 	error_exit(ret, "create writer %d", ret);
 
-	ret = scoutfs_parallel_restore_import_super(wri, super);
+	ret = scoutfs_parallel_restore_import_super(wri, super, dev_fd);
 	error_exit(ret, "import super %d", ret);
 
 	slices = calloc(1 + opts->nr_writers, sizeof(struct scoutfs_parallel_restore_slice));

tests/src/restore_copy.c

@@ -672,7 +672,7 @@ static int do_restore(struct opts *opts)
 	ret = scoutfs_parallel_restore_create_writer(&wri);
 	error_exit(ret, "create writer %d", ret);
 
-	ret = scoutfs_parallel_restore_import_super(wri, super);
+	ret = scoutfs_parallel_restore_import_super(wri, super, dev_fd);
 	error_exit(ret, "import super %d", ret);
 
 	slices = calloc(2, sizeof(struct scoutfs_parallel_restore_slice));

utils/src/parallel_restore.c

@@ -1816,13 +1816,58 @@ out:
 	return count > 0 ? 0 : err;
 }
 
+/*
+ * Here we take in a dev's fd an read its quorum blocks to see if the dev has
+ * been mounted before
+ */
+static spr_err_t scoutfs_check_if_previous_mount(int fd)
+{
+	struct scoutfs_quorum_block *blk = NULL;
+	struct scoutfs_quorum_block_event *ev;
+	u64 blkno;
+	int i, j;
+	spr_err_t err;
+
+	for (i = 0; i <  SCOUTFS_QUORUM_MAX_SLOTS; i++) {
+		blkno = SCOUTFS_QUORUM_BLKNO + i;
+		err = read_block(fd, blkno, SCOUTFS_BLOCK_SM_SHIFT, (void **)&blk);
+		if (!blk)
+			return EINVAL;
+
+		dprintf("quorum block read; quorum bklno: %llu, err_val: %d\n", blkno, err);
+		if (err) {
+			free(blk);
+			return err;
+		}
+
+		for (j = 0; j < SCOUTFS_QUORUM_EVENT_NR; j++) {
+			ev = &blk->events[j];
+			if (ev->ts.sec || ev->ts.nsec) {
+				free(blk);
+				return EINVAL;
+			}
+		}
+
+		free(blk);
+	}
+
+	return err;
+}
+
 spr_err_t scoutfs_parallel_restore_import_super(struct scoutfs_parallel_restore_writer *wri,
-						struct scoutfs_super_block *super)
+						struct scoutfs_super_block *super, int fd)
 {
 	spr_err_t err;
 	u64 start;
 	u64 len;
 
+	/*
+	 * check the device we are restoring into to make sure
+	 * that it has has never been mounted
+	 */
+	if (scoutfs_check_if_previous_mount(fd))
+		return EINVAL;
+
 	if (le64_to_cpu(super->fmt_vers) < 2)
 		return EINVAL;
 

utils/src/parallel_restore.h

@@ -97,7 +97,7 @@ spr_err_t scoutfs_parallel_restore_write_buf(struct scoutfs_parallel_restore_wri
 					     size_t *count_ret);
 
 spr_err_t scoutfs_parallel_restore_import_super(struct scoutfs_parallel_restore_writer *wri,
-						struct scoutfs_super_block *super);
+						struct scoutfs_super_block *super, int fd);
 spr_err_t scoutfs_parallel_restore_export_super(struct scoutfs_parallel_restore_writer *wri,
 						struct scoutfs_super_block *super);