Re: [PATCH 1/4] Btrfs-progs: fsck: only allow partial opening under repair mode

[David Sterba <dsterba@suse.cz>]

On Wed, May 28, 2014 at 07:20:38PM +0800, Wang Shilong wrote:
> --- a/cmds-check.c
> +++ b/cmds-check.c
> @@ -6810,8 +6810,7 @@ int cmd_check(int argc, char **argv)
>  	int option_index = 0;
>  	int init_csum_tree = 0;
>  	int qgroup_report = 0;
> -	enum btrfs_open_ctree_flags ctree_flags =
> -		OPEN_CTREE_PARTIAL | OPEN_CTREE_EXCLUSIVE;
> +	enum btrfs_open_ctree_flags ctree_flags = OPEN_CTREE_EXCLUSIVE;
>  
>  	while(1) {
>  		int c;
> @@ -6877,6 +6876,10 @@ int cmd_check(int argc, char **argv)
>  		goto err_out;
>  	}
>  
> +	/* only allow partial opening under repair mode */
> +	if (repair)
> +		ctree_flags |= OPEN_CTREE_PARTIAL;

I'm curious why. The usual way is to run fsck, look at errors and call
with --repair eventually, expecting the repair mode do fix what's
fixable.

Now this would not return the same set of errors in the non-repair mode?

This of course depends on the damage of the filesystem, but I think we
should try to let it continue as far as possible and then stop. This
probably means extra checks of the data structures before use, but this
a good pattern for fsck anyway.

> +
>  	info = open_ctree_fs_info(argv[optind], bytenr, 0, ctree_flags);
>  	if (!info) {
>  		fprintf(stderr, "Couldn't open file system\n");