btrfs-progs: handle error in the btrfs_prepare_device

this patch will handle the strerror reporting of the error instead of
printing errno,  and also replaced the BUG_ON with the error handling

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>

cmds-device.c

@@ -111,13 +111,11 @@ static int cmd_add_dev(int argc, char **argv)
 
 		res = btrfs_prepare_device(devfd, argv[i], 1, &dev_block_count,
 					   0, &mixed, discard);
-		if (res) {
-			fprintf(stderr, "ERROR: Unable to init '%s'\n", argv[i]);
-			close(devfd);
-			ret++;
-			continue;
-		}
 		close(devfd);
+		if (res) {
+			ret++;
+			goto error_out;
+		}
 
 		strncpy_null(ioctl_args.name, argv[i]);
 		res = ioctl(fdmnt, BTRFS_IOC_ADD_DEV, &ioctl_args);
@@ -130,6 +128,7 @@ static int cmd_add_dev(int argc, char **argv)
 
 	}
 
+error_out:
 	close_file_or_dir(fdmnt, dirstream);
 	return !!ret;
 }

cmds-replace.c

@@ -276,12 +276,11 @@ static int cmd_start_replace(int argc, char **argv)
 	}
 	strncpy((char *)start_args.start.tgtdev_name, dstdev,
 		BTRFS_DEVICE_PATH_NAME_MAX);
-	if (btrfs_prepare_device(fddstdev, dstdev, 1, &dstdev_block_count, 0,
-				 &mixed, 0)) {
-		fprintf(stderr, "Error: Failed to prepare device '%s'\n",
-			dstdev);
+	ret = btrfs_prepare_device(fddstdev, dstdev, 1, &dstdev_block_count, 0,
+				 &mixed, 0);
+	if (ret)
 		goto leave_with_error;
-	}
+
 	close(fddstdev);
 	fddstdev = -1;
 

mkfs.c

@@ -1445,6 +1445,10 @@ int main(int ac, char **av)
 		first_file = file;
 		ret = btrfs_prepare_device(fd, file, zero_end, &dev_block_count,
 					   block_count, &mixed, discard);
+		if (ret) {
+			close(fd);
+			exit(1);
+		}
 		if (block_count && block_count > dev_block_count) {
 			fprintf(stderr, "%s is smaller than requested size\n", file);
 			exit(1);
@@ -1552,8 +1556,11 @@ int main(int ac, char **av)
 		}
 		ret = btrfs_prepare_device(fd, file, zero_end, &dev_block_count,
 					   block_count, &mixed, discard);
+		if (ret) {
+			close(fd);
+			exit(1);
+		}
 		mixed = old_mixed;
-		BUG_ON(ret);
 
 		ret = btrfs_add_to_fsid(trans, root, fd, file, dev_block_count,
 					sectorsize, sectorsize, sectorsize);

utils.c

@@ -581,13 +581,13 @@ int btrfs_prepare_device(int fd, char *file, int zero_end, u64 *block_count_ret,
 	ret = fstat(fd, &st);
 	if (ret < 0) {
 		fprintf(stderr, "unable to stat %s\n", file);
-		exit(1);
+		return 1;
 	}
 
 	block_count = btrfs_device_size(fd, &st);
 	if (block_count == 0) {
 		fprintf(stderr, "unable to find %s size\n", file);
-		exit(1);
+		return 1;
 	}
 	if (max_block_count)
 		block_count = min(block_count, max_block_count);
@@ -612,26 +612,35 @@ int btrfs_prepare_device(int fd, char *file, int zero_end, u64 *block_count_ret,
 	}
 
 	ret = zero_dev_start(fd);
-	if (ret) {
-		fprintf(stderr, "failed to zero device start %d\n", ret);
-		exit(1);
-	}
+	if (ret)
+		goto zero_dev_error;
 
 	for (i = 0 ; i < BTRFS_SUPER_MIRROR_MAX; i++) {
 		bytenr = btrfs_sb_offset(i);
 		if (bytenr >= block_count)
 			break;
-		zero_blocks(fd, bytenr, BTRFS_SUPER_INFO_SIZE);
+		ret = zero_blocks(fd, bytenr, BTRFS_SUPER_INFO_SIZE);
+		if (ret)
+			goto zero_dev_error;
 	}
 
 	if (zero_end) {
 		ret = zero_dev_end(fd, block_count);
-		if (ret) {
-			fprintf(stderr, "failed to zero device end %d\n", ret);
-			exit(1);
-		}
+		if (ret)
+			goto zero_dev_error;
 	}
 	*block_count_ret = block_count;
+
+zero_dev_error:
+	if (ret < 0) {
+		fprintf(stderr, "ERROR: failed to zero device '%s' - %s\n",
+			file, strerror(-ret));
+		return 1;
+	} else if (ret > 0) {
+		fprintf(stderr, "ERROR: failed to zero device '%s' - %d\n",
+			file, ret);
+		return 1;
+	}
 	return 0;
 }