On Fri, Jul 04, 2014 at 09:59:13AM +0800, Gui Hecheng wrote: > > > --- a/btrfstune.c > > > +++ b/btrfstune.c > > > @@ -103,6 +104,7 @@ static void print_usage(void) > > > fprintf(stderr, "\t-S value\tpositive value will enable seeding, zero > > > to disable, negative is not allowed\n"); > > > fprintf(stderr, "\t-r \t\tenable extended inode refs\n"); > > > fprintf(stderr, "\t-x \t\tenable skinny metadata extent refs\n"); > > > + fprintf(stderr, "\t-y \t\tsay yes to clear the seeding flag, make sure > > > that you are aware of the danger\n"); > > > > The help text could say someting like > > > > "--force\tallow dangerous changes\n" > > > > btrfstune only allows setting the bit for extref and skinny-metadata, > > unsetting would be dangerous as well. > On my part, I don't find any scenarioes for these two, could you please > remind me more?
For example the extended refs add a new key type representing the hardlinks that do not fit into the leaf. Dropping the bit from incompat bits will hide that. Mounting the filesystem on kernels < 3.7 will not work as expected then. The extref key is not necessarily used even if the bit is set, only if the hardlinks do not fit, so dropping the bit will not automatically cause a disaster. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
