On Sun, Apr 05, 2015 at 03:30:47AM +0000, Russell Coker wrote: > On Sun, 5 Apr 2015 03:16:21 AM Duncan wrote: > > Hugo Mills posted on Sat, 04 Apr 2015 13:00:47 +0000 as excerpted: > > > On Sat, Apr 04, 2015 at 12:55:08PM +0000, Russell Coker wrote: > > >> As an aside are there options to mkfs.btrfs that would make a > > >> filesystem mountable by kernel 3.2.65? If so I'll file a Debian/Jessie > > >> bug report requesting that a specific mention be added to the man page. > > > > > > Yes, there are. It's probably -O^extref, but if you can show the > > > dmesg output from the 3.2 kernel on the failed mount (so that it shows > > > what the actual failure was), we should be able to give you a more > > > precise answer. > > [698190.987065] Btrfs loaded > [698190.999992] device fsid 118e2c64-6ce1-4f21-85e2-2d6aea8f0fa5 devid 1 > transid 426 /dev/sdf1 > [698191.000981] btrfs: disk space caching is enabled > [698191.000986] BTRFS: couldn't mount because of unsupported optional > features > (60).
That's these, I think: #define BTRFS_FEATURE_INCOMPAT_BIG_METADATA (1ULL << 5) #define BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF (1ULL << 6) so it's definitely -O^extref. I don't see where big_metadata comes from, though. That's not a -O option. Try with -O^extref and see where that gets you. (Also, don't mount the FS on a newer kernel -- it may be setting big metadata automatically, although it probably shouldn't do). Hugo. > [698191.018176] btrfs: open_ctree failed > > > So I was thinking about this, and the several other earlier options where > > support wasn't added until kernel X, and had an idea... > > > > How easy and useful might it be to add to mkfs.btrfs appropriate option- > > group aliases such that if one knew the oldest kernel one was likely to > > deal with, all one would need to do for the mkfs would be to set for > > example, -O3.2, or even simply --3.2 (or maybe even --32), and have > > mkfs.btrfs automatically set/unset the appropriate options so it would > > "just work" with that kernel and anything newer? > > That would be really useful. Also it would be good if the code structure > allowed adding extra aliases, so for Debian we could add an option -Owheezy. > -- Hugo Mills | Nostalgia isn't what it used to be. hugo@... carfax.org.uk | http://carfax.org.uk/ | PGP: E2AB1DE4 |
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