Re: [PATCH v2 08/10] btrfs-progs: undelete-subvol: add undelete-subvol subcommand

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

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On 2018年03月27日 15:06, Lu Fengqi wrote:
> Add the undelete-subvol subcommand for btrfs rescue. This subcommand is
> used to recover deleted subvolume left intact on the device.
> 
> Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
> ---
> v2: add -s option to specify subvol_id.
> 
>  cmds-rescue.c | 70 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 70 insertions(+)
> 
> diff --git a/cmds-rescue.c b/cmds-rescue.c
> index c40088ad374e..c5132126e922 100644
> --- a/cmds-rescue.c
> +++ b/cmds-rescue.c
> @@ -25,6 +25,7 @@
>  #include "disk-io.h"
>  #include "commands.h"
>  #include "utils.h"
> +#include "undelete-subvol.h"
>  #include "help.h"
>  
>  static const char * const rescue_cmd_group_usage[] = {
> @@ -248,6 +249,73 @@ out:
>  	return !!ret;
>  }
>  
> +static const char * const cmd_rescue_undelete_subvol_usage[] = {
> +	"btrfs rescue undelete-subvol [-s <subvolid>] <device>",
> +	"Undelete deleted subvolume",
> +	"All deleted subvolume that still left intact on the device will be",
> +	"recovered. If -s <subvolid> option is given, then just recover the",
> +	"subvolume which specified by <subvolid>.",
> +	"",
> +	"-s <subvolid>	specify the subvolume which will be recovered.",
> +	NULL
> +};
> +
> +static int cmd_rescue_undelete_subvol(int argc, char **argv)
> +{
> +	struct btrfs_fs_info *fs_info;
> +	char *devname;
> +	u64 subvol_id = 0;
> +	int ret;
> +
> +	while (1) {
> +		int c = getopt(argc, argv, "s:");
> +
> +		if (c < 0)
> +			break;
> +		switch (c) {
> +		case 's':
> +			subvol_id = arg_strtou64(optarg);
> +			if (!is_fstree(subvol_id)) {
> +				error("%llu is not a valid subvolume id",
> +						subvol_id);
> +				ret = -EINVAL;
> +				goto out;
> +			}
> +			break;
> +		default:
> +			usage(cmd_rescue_undelete_subvol_usage);
> +		}
> +	}
> +
> +	if (check_argc_exact(argc - optind, 1))
> +		usage(cmd_rescue_undelete_subvol_usage);
> +
> +	devname = argv[optind];
> +	ret = check_mounted(devname);
> +	if (ret < 0) {
> +		error("could not check mount status: %s", strerror(-ret));
> +		goto out;
> +	} else if (ret) {
> +		error("%s is currently mounted", devname);
> +		ret = -EBUSY;
> +		goto out;
> +	}
> +
> +	fs_info = open_ctree_fs_info(devname, 0, 0, 0, OPEN_CTREE_WRITES |
> +				     OPEN_CTREE_PARTIAL);

I'm not sure if using OPEN_CTREE_PARTIAL here is a good idea.

As the undelete-subvol looks like a tool to revert stupid user mistake,
and we expect a healthy fs to be provided.
And for corrupted fs, we may make the case worse.

Thanks,
Qu

> +	if (!fs_info) {
> +		error("could not open btrfs");
> +		ret = -EIO;
> +		goto out;
> +	}
> +
> +	ret = btrfs_undelete_intact_subvols(fs_info->tree_root, subvol_id);
> +
> +	close_ctree(fs_info->tree_root);
> +out:
> +	return ret;
> +}
> +
>  static const char rescue_cmd_group_info[] =
>  "toolbox for specific rescue operations";
>  
> @@ -260,6 +328,8 @@ const struct cmd_group rescue_cmd_group = {
>  		{ "zero-log", cmd_rescue_zero_log, cmd_rescue_zero_log_usage, NULL, 0},
>  		{ "fix-device-size", cmd_rescue_fix_device_size,
>  			cmd_rescue_fix_device_size_usage, NULL, 0},
> +		{ "undelete-subvol", cmd_rescue_undelete_subvol,
> +			cmd_rescue_undelete_subvol_usage, NULL, 0},
>  		NULL_CMD_STRUCT
>  	}
>  };
> 


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