Re: [PATCH 1/2] btrfs-progs: fi show: Print missing device for a mounted file system

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

On 2021/9/2 下午6:06, Nikolay Borisov wrote:
> Currently when a device is missing for a mounted filesystem the output
> that is produced is unhelpful:
>
> Label: none  uuid: 139ef309-021f-4b98-a3a8-ce230a83b1e2
> 	Total devices 2 FS bytes used 128.00KiB
> 	devid    1 size 5.00GiB used 1.26GiB path /dev/loop0
> 	*** Some devices missing
>
> While the context which prints this is perfectly capable of showing
> which device exactly is missing, like so:
>
> Label: none  uuid: 4a85a40b-9b79-4bde-8e52-c65a550a176b
> 	Total devices 2 FS bytes used 128.00KiB
> 	devid    1 size 5.00GiB used 1.26GiB path /dev/loop0
> 	devid    2 size 0 used 0 path /dev/loop1 ***MISSING***
>
> This is a lot more usable output as it presents the user with the id
> of the missing device and its path.

The idea is pretty awesome.

Just one question, if one device is missing, how could we know its path?
Thus does the device path output make any sense?

Thanks,
Qu
>
> Signed-off-by: Nikolay Borisov <nborisov@suse.com>
> ---
>   cmds/filesystem.c | 7 +++----
>   1 file changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/cmds/filesystem.c b/cmds/filesystem.c
> index db8433ba3542..ff13de6ac990 100644
> --- a/cmds/filesystem.c
> +++ b/cmds/filesystem.c
> @@ -295,7 +295,6 @@ static int print_one_fs(struct btrfs_ioctl_fs_info_args *fs_info,
>   {
>   	int i;
>   	int fd;
> -	int missing = 0;
>   	char uuidbuf[BTRFS_UUID_UNPARSED_SIZE];
>   	struct btrfs_ioctl_dev_info_args *tmp_dev_info;
>   	int ret;
> @@ -325,8 +324,10 @@ static int print_one_fs(struct btrfs_ioctl_fs_info_args *fs_info,
>   		/* Add check for missing devices even mounted */
>   		fd = open((char *)tmp_dev_info->path, O_RDONLY);
>   		if (fd < 0) {
> -			missing = 1;
> +			printf("\tdevid %4llu size 0 used 0 path %s ***MISSING***\n",
> +					tmp_dev_info->devid,tmp_dev_info->path);
>   			continue;
> +
>   		}
>   		close(fd);
>   		canonical_path = path_canonicalize((char *)tmp_dev_info->path);
> @@ -339,8 +340,6 @@ static int print_one_fs(struct btrfs_ioctl_fs_info_args *fs_info,
>   		free(canonical_path);
>   	}
>
> -	if (missing)
> -		printf("\t*** Some devices missing\n");
>   	printf("\n");
>   	return 0;
>   }
>