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 > > I'm happy to hear it is still disabled in Ubuntu, where many more > users would be affected. IIRC OpenSUSE LEAP and SLED 15 reenabled it > (it was previously disabled there), so maybe it needs specific kernel > versions or patches to not trigger RC bugs, and/or very specific > btrfs-progs versions, and/or very specific e2fslibs, and/or specific > combinations? While I very much look forward to the day when > btrfs-convert can be relied on in Debian, I don't think we're there > yet. Please take this as an opportunity to test that your backups are > restorable, mkfs.btrfs, and then restore from backup. P.S. I have no > idea if Ubuntu has additional btrfs support. > > Cheers, > Nicholas >
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