On 2018/8/24 下午3:54, Misono Tomohiro wrote:
> On 2018/08/24 16:20, Qu Wenruo wrote:
>>
>>
>> On 2018/8/24 下午3:14, Misono Tomohiro wrote:
>>> Hi,
>>>
>>> On 2018/08/21 14:40, Qu Wenruo wrote:
>>>> Commit c6887cd11149 ("Btrfs: don't do nocow check unless we have to")
>>>> makes nocow check less frequent to improve performance.
>>>>
>>>> However for quota enabled case, such optimization could lead to extra
>>>> unnecessary data reservation, which results failure for test case like
>>>> btrfs/153 in fstests.
>>>>
>>>> Fix it by reverting to old behavior for quota enabled case.
>>>>
>>>> Fixes: c6887cd11149 ("Btrfs: don't do nocow check unless we have to")
>>>> Signed-off-by: Qu Wenruo <w...@suse.com>
>>>> ---
>>>> changelog
>>>> v2:
>>>> Fix regression for quota+cow case. (Previously it will skip data
>>>> reservation if quota is enabled, causing regression for limit case.
>>>> Pointed out by Misono)
>>>> ---
>>>> fs/btrfs/file.c | 18 +++++++++++++++++-
>>>> 1 file changed, 17 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
>>>> index 2be00e873e92..183e5fb96f42 100644
>>>> --- a/fs/btrfs/file.c
>>>> +++ b/fs/btrfs/file.c
>>>> @@ -1584,6 +1584,7 @@ static noinline ssize_t btrfs_buffered_write(struct
>>>> kiocb *iocb,
>>>> int ret = 0;
>>>> bool only_release_metadata = false;
>>>> bool force_page_uptodate = false;
>>>> + bool quota_enabled = test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags);
>>>>
>>>> nrptrs = min(DIV_ROUND_UP(iov_iter_count(i), PAGE_SIZE),
>>>> PAGE_SIZE / (sizeof(struct page *)));
>>>> @@ -1624,13 +1625,28 @@ static noinline ssize_t
>>>> btrfs_buffered_write(struct kiocb *iocb,
>>>> fs_info->sectorsize);
>>>>
>>>> extent_changeset_release(data_reserved);
>>>> +
>>>> + /*
>>>> + * If we have quota enabled, we must do the heavy lift nocow
>>>> + * check here to avoid reserving data space, or we can hit
>>>> + * limitation for NOCOW files.
>>>> + */
>>>> + if (quota_enabled) {
>>>> + if ((BTRFS_I(inode)->flags & (BTRFS_INODE_NODATACOW |
>>>> + BTRFS_INODE_PREALLOC)) &&
>>>> + check_can_nocow(BTRFS_I(inode), pos,
>>>> + &write_bytes) > 0)
>>>> + goto reserve_meta_only;
>>>> + }
>>>> ret = btrfs_check_data_free_space(inode, &data_reserved, pos,
>>>> write_bytes);
>>>> if (ret < 0) {
>>>> if ((BTRFS_I(inode)->flags & (BTRFS_INODE_NODATACOW |
>>>> BTRFS_INODE_PREALLOC)) &&
>>>> check_can_nocow(BTRFS_I(inode), pos,
>>>> - &write_bytes) > 0) {
>>>> + &write_bytes) > 0 &&
>>>
>>>> + !quota_enabled) {
>>>
>>> (When we check this condition, quota_enabled must be false or otherwise
>>> we have already goto reserve_meta_only. So it seems redundant.)
>>
>> It's possible that we have quota enabled, and then
>> btrfs_check_data_free_space() failed with -EDQUOT.
>>
>> In that case, we need above !quota_enabled check to avoid unnecessary
>> check and just go error branch.
>
> So should quota_enabled be checked before check_can_nocow()?
Oh, yes, it should be put before nocow check.
>
>>
>>>
>>>> +reserve_meta_only:
>>>> /*
>>>> * For nodata cow case, no need to reserve
>>>> * data space.
>>>>
>>>
>>> I applied this patch on today's misc-next and it seems mostly ok, but
>>> btrfs/022 sometimes gives following warning:
>>
>> This looks like related to the regression caused by commit
>> c4c129db5da8f070147f175 ("btrfs: drop unused
>> parameter qgroup_reserved").
>>
>> Would you please try reverting that patch?
>
> I think above commit is fixed by commit eb27db470 ("btrfs: fix
> qgroup_free wrong num_bytes in btrfs_subvolume_reserve_metadata") which
> is already in misc-next too.
>
> I reverted above two patch (and one more related patch 6b0cb14901
> ("btrfs: drop useless member qgroup_reserved of btrfs_pending_snapshot")),
> but get the same result.
So something really goes wrong.
I assume it's some error handler which double freed, but a quick glance
nor my initial test run doesn't show something obvious.
BTW, what's the possibility of such problem in your test environment?
Thanks,
Qu
>
> Thanks,
> Misono
>
>>
>> Thanks,
>> Qu
>>
>>
>>>
>>> [80244.152130] WARNING: CPU: 5 PID: 14575 at fs/btrfs/extent-tree.c:9742
>>> btrfs_free_block_groups+0x2d7/0x440 [btrfs]
>>> [80244.152132] Modules linked in: btrfs(O) xor zstd_decompress
>>> zstd_compress xxhash raid6_pq xt_CHECKSUM ipt_MASQUERADE tun bridge stp llc
>>> xt_conntrack ip_set nfnetlink iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4
>>> nf_nat_ipv4 nf_nat nf_conntrack iptable_mangle iptable_raw iptable_security
>>> sunrpc intel_powerclamp kvm_intel kvm gpio_ich iTCO_wdt ipmi_ssif
>>> iTCO_vendor_support ipmi_si st irqbypass ipmi_devintf crct10dif_pclmul
>>> crc32_pclmul ipmi_msghandler ghash_clmulni_intel pcspkr acpi_power_meter
>>> i2c_i801 pcc_cpufreq i7core_edac lpc_ich acpi_cpufreq xfs libcrc32c mgag200
>>> drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ttm drm igb
>>> sr_mod hwmon uas ptp crc32c_intel cdrom usb_storage pps_core ata_generic
>>> megaraid_sas dca pata_acpi i2c_algo_bit ipv6 [last unloaded: xor]
>>> [80244.152185] CPU: 5 PID: 14575 Comm: umount Tainted: G W IO
>>> 4.18.0-rc8+ #98
>>> [80244.152187] Hardware name: FUJITSU-SV PRIMERGY
>>> RX300 S6 /D2619, BIOS 6.00 Rev. 1.09.2619.N1
>>> 12/13/2010
>>> [80244.152205] RIP: 0010:btrfs_free_block_groups+0x2d7/0x440 [btrfs]
>>> [80244.152206] Code: 85 20 cb 00 00 48 39 c6 0f 84 b9 00 00 00 49 bf 00 01
>>> 00 00 00 00 ad de 48 8b 9d 20 cb 00 00 48 83 7b a0 00 0f 84 0d 01 00 00
>>> <0f> 0b 48 8d 73 88 31 c9 31 d2 48 89 ef e8 27 7a ff ff 48 89 df e8
>>> [80244.152235] RSP: 0018:ffff8ea10393fdb0 EFLAGS: 00010286
>>> [80244.152237] RAX: ffff8c1025819e78 RBX: ffff8c1025819e78 RCX:
>>> 0000000000000000
>>> [80244.152238] RDX: 0000000000000001 RSI: ffff8c115329cb20 RDI:
>>> ffff8c1025818e00
>>> [80244.152239] RBP: ffff8c1153290000 R08: 0000000000000000 R09:
>>> 0000000000000000
>>> [80244.152240] R10: ffff8c1025818e98 R11: 0000000000000002 R12:
>>> ffff8c11532900a0
>>> [80244.152241] R13: 0000000000000000 R14: dead000000000200 R15:
>>> dead000000000100
>>> [80244.152243] FS: 00007ff0cc3d8fc0(0000) GS:ffff8c1137d40000(0000)
>>> knlGS:0000000000000000
>>> [80244.152244] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>> [80244.152245] CR2: 00007ffe75e53c88 CR3: 0000000235d16001 CR4:
>>> 00000000000206e0
>>> [80244.152246] Call Trace:
>>> [80244.152270] close_ctree+0x146/0x320 [btrfs]
>>> [80244.152276] ? kthread_stop+0x42/0xf0
>>> [80244.152280] generic_shutdown_super+0x6c/0x110
>>> [80244.152283] kill_anon_super+0xe/0x20
>>> [80244.152298] btrfs_kill_super+0x13/0x100 [btrfs]
>>> [80244.152301] deactivate_locked_super+0x3f/0x70
>>> [80244.152303] cleanup_mnt+0x3b/0x70
>>> [80244.152305] task_work_run+0x84/0xa0
>>> [80244.152308] do_syscall_64+0x143/0x4cd
>>> [80244.152311] ? do_page_fault+0x31/0x130
>>> [80244.152314] entry_SYSCALL_64_after_hwframe+0x44/0xa9
>>> [80244.152316] RIP: 0033:0x7ff0cb43c1a7
>>> [80244.152317] Code: ad 2b 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00
>>> 00 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05
>>> <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d c9 ac 2b 00 f7 d8 64 89 01 48
>>> [80244.152346] RSP: 002b:00007ffe75e554b8 EFLAGS: 00000246 ORIG_RAX:
>>> 00000000000000a6
>>> [80244.152348] RAX: 0000000000000000 RBX: 0000563ccced82d0 RCX:
>>> 00007ff0cb43c1a7
>>> [80244.152349] RDX: 0000000000000001 RSI: 0000000000000000 RDI:
>>> 0000563ccced84b0
>>> [80244.152350] RBP: 0000563ccced84b0 R08: 0000000000000005 R09:
>>> 0000563ccced84d0
>>> [80244.152351] R10: 00007ff0cb4ba320 R11: 0000000000000246 R12:
>>> 00007ff0cc1d0184
>>> [80244.152352] R13: 0000000000000000 R14: 0000000000000000 R15:
>>> 0000000000000000
>>> [80244.152354] ---[ end trace b5975ec96174c60c ]---
>>> [80244.152358] BTRFS info (device sdh2): space_info 1 has 1022132224 free,
>>> is not full
>>> [80244.152360] BTRFS info (device sdh2): space_info total=1082130432,
>>> used=60039168, pinned=0, reserved=0, may_use=18446744073709510656,
>>> readonly=0
>>>
>>> Obviously, may_use value is underflowed.
>>>
>>> Thanks,
>>> Misono
>>>
>>>
>>
>
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