On Tue, Nov 28, 2023 at 10:23:41PM -0800, Christoph Hellwig wrote: > On Tue, Nov 28, 2023 at 10:21:55PM -0800, Darrick J. Wong wrote: > > On Tue, Nov 28, 2023 at 10:05:49PM -0800, Christoph Hellwig wrote: > > > On Tue, Nov 28, 2023 at 03:30:09PM -0800, Darrick J. Wong wrote: > > > > LOL so I just tried a 64k rt volume with a 1M rextsize and mkfs crashed. > > > > I guess I'll go sort out what's going on there... > > > > > > I think we should just reject rt device size < rtextsize configs in > > > the kernel and all tools. > > > > "But that could break old weirdass customer filesystems." > > > > The design of rtgroups prohibits that, so we're ok going forward. > > Well, as you just said it hasn't mounted for a long time, and really > this is a corner case that just doesn't make any sense. I'd really > prefer to cleanly reject it, and if someone really complains with a good > reason we can revisit the decisions. But I strongly doubt it's ever > going to happen. Oh, even better, Dave and I noticed today that if you format a 17G realtime volume (> 2^32 rt extents) then mkfs fails because there's an integer overflow: https://git.kernel.org/pub/scm/fs/xfs/xfsprogs-dev.git/tree/mkfs/xfs_mkfs.c#n3739 Based on your observation that rt free space never exceeds the group length with rtgroups turned on, I'll tweak the sb_rextslog computation so that it's computed with (rgblocks / rextsize) instead of (rblocks / rextsize) which will fix that problem for future filesystems. --D
