Re: [RFC] Subvolume Quota on-disk structures and configuration

[Phillip Susi <psusi@cfl.rr.com>]

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On 07/10/2011 04:21 AM, Arne Jansen wrote:
> Now that I've got a working prototype of subvolume quota, I'd like
> to get some feedback on the on-disk structure and the commands I
> intend to use.

I think I've noticed a bug so far, and have one comment on the qgroup show command.  The command seems to show the current usage of the qgroup, but I can't see how to view the limits ( if any ).  It seems like the show command should show both.

The bug I seem to have noticed is that rm fails with EQUOTA.  I set a 1g limit on a new subvol, and ran dd if=/dev/zero of=/mnt/foo, which created a file approx 1g in size before erroring out with EQUOTA.  After that, I did an echo bar /mnt/bar, and to my surprise, this did not fail with EQUOTA.  Now when I try to rm /mnt/bar or /mnt/foo, THAT fails with EQUOTA.  I also got this in dmesg:

[  992.078275] WARNING: at fs/btrfs/inode.c:6670 btrfs_destroy_inode+0x31d/0x360 [btrfs]()
[  992.078276] Hardware name: System Product Name
[  992.078277] Modules linked in: nls_utf8 isofs bnep rfcomm kvm_intel kvm parport_pc ppdev dm_crypt binfmt_misc nls_iso8859_1 nls_cp437 vfat fat snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_seq_midi snd_rawmidi snd_seq_midi_event joydev snd_seq psmouse eeepc_wmi asus_wmi snd_timer snd_seq_device btusb bluetooth serio_raw snd sparse_keymap soundcore mei(C) snd_page_alloc w83627ehf hwmon_vid coretemp lp parport raid10 raid456 async_pq async_xor async_memcpy async_raid6_recov raid6_pq async_tx raid1 raid0 multipath linear dm_raid45 xor dm_mirror dm_region_hash dm_log btrfs zlib_deflate libcrc32c hid_microsoft usbhid hid mxm_wmi wmi radeon ahci libahci ttm drm_kms_helper e1000e xhci_hcd drm i2c_algo_bit zram(C)
[  992.078305] Pid: 2342, comm: rm Tainted: G         C   3.2.0-rc2+ #7
[  992.078306] Call Trace:
[  992.078311]  [<ffffffff81062acf>] warn_slowpath_common+0x7f/0xc0
[  992.078313]  [<ffffffff81062b2a>] warn_slowpath_null+0x1a/0x20
[  992.078320]  [<ffffffffa020de9d>] btrfs_destroy_inode+0x31d/0x360 [btrfs]
[  992.078324]  [<ffffffff811895cc>] destroy_inode+0x3c/0x70
[  992.078326]  [<ffffffff8118972a>] evict+0x12a/0x1c0
[  992.078328]  [<ffffffff811898c9>] iput+0x109/0x220
[  992.078331]  [<ffffffff8117e7b3>] do_unlinkat+0x153/0x1d0
[  992.078333]  [<ffffffff811740ea>] ? sys_newfstatat+0x2a/0x40
[  992.078334]  [<ffffffff8117f352>] sys_unlinkat+0x22/0x40
[  992.078337]  [<ffffffff8160d0c2>] system_call_fastpath+0x16/0x1b
[  992.078338] ---[ end trace 770bc93001697fbc ]---

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