Re: [PATCH] btrfs-progs: convert, warn if converting a fs which won't mount

[Nikolay Borisov <nborisov@suse.com>]

On 28.02.20 г. 10:03 ч., Anand Jain wrote:
> On aarch64 with pagesize 64k, btrfs-convert of ext4 is successful,
> but it won't mount because we don't yet support subpage blocksize/
> sectorsize.
> 
>  BTRFS error (device vda): sectorsize 4096 not supported yet, only support 65536
> 
> So in this case during convert provide a warning and a 10s delay to
> terminate the command.
> 
> For example:
> 
> WARNING: Blocksize 4096 is not equal to the pagesize 65536,
>          converted filesystem won't mount on this system.
>          The operation will start in 10 seconds. Use Ctrl-c to stop it.
> 10 9 8 7 6 5 4^C

What's the point of the delay? Just refuse to start the operation and quit.

> 
> Signed-off-by: Anand Jain <anand.jain@oracle.com>
> ---
>  convert/main.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/convert/main.c b/convert/main.c
> index a04ec7a36abf..f936ec37d30a 100644
> --- a/convert/main.c
> +++ b/convert/main.c
> @@ -1140,6 +1140,21 @@ static int do_convert(const char *devname, u32 convert_flags, u32 nodesize,
>  		error("block size is too small: %u < 4096", blocksize);
>  		goto fail;
>  	}
> +	if (blocksize != getpagesize()) {
> +		int delay = 10;
> +
> +		warning("Blocksize %u is not equal to the pagesize %u,\n\
> +         converted filesystem won't mount on this system.\n\
> +         The operation will start in %d seconds. Use Ctrl-C to stop it.",
> +			blocksize, getpagesize(), delay);
> +
> +		while (delay) {
> +			printf("%2d", delay--);
> +			fflush(stdout);
> +			sleep(1);
> +		}
> +	}
> +
>  	if (btrfs_check_nodesize(nodesize, blocksize, features))
>  		goto fail;
>  	fd = open(devname, O_RDWR);
>