Hi Qu, On Sun, Jul 29, 2018 at 07:44:05AM +0800, Qu Wenruo wrote: > > > On 2018年07月29日 05:34, Nicholas D Steeves wrote: > > Resending because I forgot to CC list. > > > > Hi jkexcel, > > > > On 28 July 2018 at 16:50, jkexcel <jkexcel@xxxxxxxxxxx> wrote: > >> > >> I'm an end user trying to use btrfs-convert but when I installed > >> btrfs-tools and its dependency btrfs-progs on kubuntu 18.04, the > >> installation was successful, and it shows that v4.15.1-1build1 was > >> installed. > >> > >> However, when using the command # brtfs-convert /dev/sda4 (with the > >> drive unmounted) the resulting error appears "command not found" > >> I also tried command "btrfs convert" in case this was folded into the > >> main tool, but this also failed. > >> > >> 1. Is btrfs-convert still available? > >> > >> 2. Where can I find it? > >> > >> 3. Has btrfs-convert been replaced? what is it's new name? > >> > >> 4. Is it safe to use a downgraded version of btrfs-tools ie: 4.14 or > >> older? > > > > You can blame me for that. In Debian several users had reported > > release-critical issues in btrfs-convert, so I submitted a patch to > > disable it for the forseable future, eg: > > > > https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=864798 > > https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=854489 > > Both report looks pretty old (4.7~4.9). > > In fact, just in v4.10 we had a big rework for convert. > It should work much better after that. > > Furthermore, we have newer (but smaller) fixes to remove a lot of > BUG_ON(), and do graceful exit for ENOSPC case since then. > > And the design of btrfs-convert (at least for the latest btrfs-convert) > is to ensure until everything goes well, we won't touch any bytes of the > ext* fs (in fact we open the ext* fs in RO mode). > So it at least won't corrupt the ext* fs. > > > > > Also, please consider the official status "As of 4.0 kernels this feature > > is not often used or well tested anymore, and there have been some reports > > that the conversion doesn't work reliably. Feel free to try it out, but > > make sure you have backups" ( > > https://btrfs.wiki.kernel.org/index.php/Conversion_from_Ext3 ). > > The wiki page looks needs to be updated. > > Both btrfs-convert and base btrfs-progs are improving, especially after > v4.10 btrfs-convert goes through a big rework and works well so far, and > even added support for reiserfs under the same framwork. > > So IMHO it's at least worth trying. > > Thanks, > Qu Thank you for sharing the cut-off where success became more likely :-) Debian 9 could have had 4.9.1 at the newest, so it wouldn't have had btrfs-convert. So it sounds like btrfs-convert could have been enabled for the experimental suite (which is almost only used by Debian developers and not users) for 4.10. Looking at the changelog it seems we might have had to disable it again before 4.14.1 or 4.16. I'm happy we're having this conversation now, because the time to give it another try is probably sometime in the next month :-) See my long email to David for the caveats. Cheers, Nicholas
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