On Wed, Nov 12, 2014 at 06:48:47PM +0000, Kline, Matthew wrote: > Yesterday I converted my ext4 root and home partitions on my home machine > to btrfs using btrfs-convert. After confirming that everything went well, > I followed the wiki instructions to nuke the 'ext2_saved" subvolume, > then defraggad and rebalanced. Everything went according to plan on my root > partition, but my home partition claimed to have run out of space > when rebalancing. > > I did some digging and tried the following to resolve the problem, > but to no avail. So far I have: > > - Made sure I deleted the subvolume (a common cause of this problem). > `sudo btrfs subvolume list -a /home` exits with no output. > > - Made sure I defragged the newly converted btrfs partition before attempting > to rebalance it. > > - Made sure that I actually have space on the partition. > It is only about 60% full - see sdb1 below: > > ~ % sudo btrfs fi show > Label: none uuid: 3a154348-9bd4-4c3f-aaf8-e9446d3797db > Total devices 1 FS bytes used 9.49GiB > devid 1 size 87.47GiB used 11.03GiB path /dev/sda3 > > Label: none uuid: cc90ee50-bbda-46d6-a7e6-fe1c8578d75b > Total devices 1 FS bytes used 124.98GiB > devid 1 size 200.00GiB used 127.03GiB path /dev/sdb1 > > - Made sure I have metadata space (as suggested on the problem FAQ): > > ~ % sudo btrfs fi df /home > Data, single: total=126.00GiB, used=124.58GiB > System, single: total=32.00MiB, used=20.00KiB > Metadata, single: total=1.00GiB, used=404.27MiB > GlobalReserve, single: total=136.00MiB, used=0.00B > > - Ran partial rebalances using the `-dusage` flag > (as suggested on the problem FAQ), > which successfully balanced a handful of blocks. > > - Checked the system log - nothing interesting comes up. > btrfs happily chugs along with "found xxx extents" and > "relocating block group xxxxx flags 1" messages before unceremoniously > ending with "7 enospc errors during balance". > > In spite of all of this, a full rebalance still fails when it's about 95% > done. > I'm at a complete loss as to what could be causing it - I know that it's not > completely necessary (especially with a single drive), > and `btrfs scrub` finds no errors with the file system, > but the wiki gives the impression that it's a good idea after you convert from > ext.
I'm fairly sure it's a bug. We've had several reports of something like this, particularly with respect to converted filesystems. I know that failed balances with apparently plenty of space are reasonably high up on josef's list of things to investigate. I would recommend at minimum putting this report on bugzilla.kernel.org as well. The other thing you could do, which may help with debugging, is to take a copy of the metadata: $ btrfs-image -c9 -t4 /dev/sdb1 /path/to/image.img and hang on to it just in case josef (or whoever else looks at it) needs another sample to debug with. > Is there something I'm missing? I don't think so. This is probably a bug -- I'd guess in the FS (because we've seen something similar on non-converted FSes), but maybe set up more easily by the conversion process. Hugo. > Other obligatory info: I'm on Arch Linux using btrfs 3.17.1. uname -a is > > Linux kline-arch 3.17.2-1-ARCH #1 SMP PREEMPT Thu Oct 30 20:49:39 CET 2014 > x86_64 GNU/Linux -- === Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk === PGP key: 65E74AC0 from wwwkeys.eu.pgp.net or http://www.carfax.org.uk --- Strive for apathy! ---
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