On 09/15/15 17:50, Holger Hoffstätte wrote:
> This V2 does indeed seem to fix the issues I reported with snapshot
> deletion & concurrent sync. I've now created/filled/deleted countless
> snapshots while issuing sync(s) in parallel, and the problem that I
> saw fairly frequently with V1 no longer seems to occur here.
Well..I may have spoken too soon:
[20502.470227] ------------[ cut here ]------------
[20502.470247] WARNING: CPU: 0 PID: 27322 at fs/btrfs/transaction.c:66 btrfs_put_transaction+0xb7/0x100 [btrfs]()
[20502.470248] Modules linked in: btrfs nfsd auth_rpcgss oid_registry lockd grace sunrpc sch_fq_codel xor snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic x86_pkg_temp_thermal coretemp raid6_pq crc32_pclmul i915 crc32c_intel aesni_intel snd_hda_intel aes_x86_64 intel_gtt glue_helper lrw snd_hda_controller i2c_algo_bit gf128mul ablk_helper drm_kms_helper snd_hda_codec cryptd usbhid snd_hda_core drm snd_pcm i2c_i801 snd_timer snd r8169 i2c_core soundcore mii video [last unloaded: btrfs]
[20502.470279] CPU: 0 PID: 27322 Comm: btrfs-transacti Not tainted 4.1.7 #1
[20502.470280] Hardware name: System manufacturer System Product Name/P8Z68-V LX, BIOS 4105 07/01/2013
[20502.470281] ffffffffa0843635 ffff8800c096fd48 ffffffff8156eae1 0000000000000007
[20502.470282] 0000000000000000 ffff8800c096fd88 ffffffff8105098a 0000000000000296
[20502.470284] ffff8802865a1d40 ffff8802865a1d40 ffff88014b5b5678 0000000000000000
[20502.470285] Call Trace:
[20502.470289] [<ffffffff8156eae1>] dump_stack+0x45/0x57
[20502.470292] [<ffffffff8105098a>] warn_slowpath_common+0x8a/0xc0
[20502.470293] [<ffffffff81050a7a>] warn_slowpath_null+0x1a/0x20
[20502.470298] [<ffffffffa07c1027>] btrfs_put_transaction+0xb7/0x100 [btrfs]
[20502.470303] [<ffffffffa07c280d>] btrfs_commit_transaction+0xb3d/0xc10 [btrfs]
[20502.470308] [<ffffffffa07bd305>] transaction_kthread+0x245/0x260 [btrfs]
[20502.470313] [<ffffffffa07bd0c0>] ? btrfs_cleanup_transaction+0x540/0x540 [btrfs]
[20502.470315] [<ffffffff8106ddc9>] kthread+0xc9/0xe0
[20502.470317] [<ffffffff8106dd00>] ? kthread_worker_fn+0x170/0x170
[20502.470319] [<ffffffff81573f52>] ret_from_fork+0x42/0x70
[20502.470320] [<ffffffff8106dd00>] ? kthread_worker_fn+0x170/0x170
[20502.470321] ---[ end trace 0556ec192b60907f ]---
[20532.457806] ------------[ cut here ]------------
[20532.457828] WARNING: CPU: 0 PID: 27322 at fs/btrfs/transaction.c:66 btrfs_put_transaction+0xb7/0x100 [btrfs]()
[20532.457829] Modules linked in: btrfs nfsd auth_rpcgss oid_registry lockd grace sunrpc sch_fq_codel xor snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic x86_pkg_temp_thermal coretemp raid6_pq crc32_pclmul i915 crc32c_intel aesni_intel snd_hda_intel aes_x86_64 intel_gtt glue_helper lrw snd_hda_controller i2c_algo_bit gf128mul ablk_helper drm_kms_helper snd_hda_codec cryptd usbhid snd_hda_core drm snd_pcm i2c_i801 snd_timer snd r8169 i2c_core soundcore mii video [last unloaded: btrfs]
[20532.457872] CPU: 0 PID: 27322 Comm: btrfs-transacti Tainted: G W 4.1.7 #1
[20532.457873] Hardware name: System manufacturer System Product Name/P8Z68-V LX, BIOS 4105 07/01/2013
[20532.457873] ffffffffa0843635 ffff8800c096fd48 ffffffff8156eae1 0000000000000007
[20532.457875] 0000000000000000 ffff8800c096fd88 ffffffff8105098a 0000000000000296
[20532.457876] ffff8802865a1d40 ffff8802865a1d40 ffff8801123dc678 0000000000000000
[20532.457878] Call Trace:
[20532.457882] [<ffffffff8156eae1>] dump_stack+0x45/0x57
[20532.457884] [<ffffffff8105098a>] warn_slowpath_common+0x8a/0xc0
[20532.457885] [<ffffffff81050a7a>] warn_slowpath_null+0x1a/0x20
[20532.457890] [<ffffffffa07c1027>] btrfs_put_transaction+0xb7/0x100 [btrfs]
[20532.457895] [<ffffffffa07c280d>] btrfs_commit_transaction+0xb3d/0xc10 [btrfs]
[20532.457901] [<ffffffffa07bd305>] transaction_kthread+0x245/0x260 [btrfs]
[20532.457905] [<ffffffffa07bd0c0>] ? btrfs_cleanup_transaction+0x540/0x540 [btrfs]
[20532.457907] [<ffffffff8106ddc9>] kthread+0xc9/0xe0
[20532.457909] [<ffffffff8106dd00>] ? kthread_worker_fn+0x170/0x170
[20532.457911] [<ffffffff81573f52>] ret_from_fork+0x42/0x70
[20532.457912] [<ffffffff8106dd00>] ? kthread_worker_fn+0x170/0x170
[20532.457913] ---[ end trace 0556ec192b609080 ]---
As expected pid 27322 is the [btrfs-transacti] thread. It now seems to happen
(just did twice in a row) when I delete a snapshot but *don't* sync, but instead
just let it smurf along all by itself.
This warning is from:
..
void btrfs_put_transaction(struct btrfs_transaction *transaction)
{
WARN_ON(atomic_read(&transaction->use_count) == 0);
if (atomic_dec_and_test(&transaction->use_count)) {
BUG_ON(!list_empty(&transaction->list));
WARN_ON(!RB_EMPTY_ROOT(&transaction->delayed_refs.href_root));
if (transaction->delayed_refs.pending_csums)
..
Once this happens unmounting results in:
..blabla..
[21618.982176] BTRFS error (device sdc1): unable to find ref byte nr 628535836672 parent 0 root 1 owner 0 offset 0
[21618.982176] ------------[ cut here ]------------
[21618.982181] WARNING: CPU: 1 PID: 387 at fs/btrfs/extent-tree.c:6363 __btrfs_free_extent.isra.33+0x960/0xdf0 [btrfs]()
[21618.982181] BTRFS: Transaction aborted (error -2)
[21618.982182] Modules linked in: btrfs nfsd auth_rpcgss oid_registry lockd grace sunrpc sch_fq_codel xor snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic x86_pkg_temp_thermal coretemp raid6_pq crc32_pclmul i915 crc32c_intel aesni_intel snd_hda_intel aes_x86_64 intel_gtt glue_helper lrw snd_hda_controller i2c_algo_bit gf128mul ablk_helper drm_kms_helper snd_hda_codec cryptd usbhid snd_hda_core drm snd_pcm i2c_i801 snd_timer snd r8169 i2c_core soundcore mii video [last unloaded: btrfs]
[21618.982196] CPU: 1 PID: 387 Comm: umount Tainted: G W 4.1.7 #1
[21618.982196] Hardware name: System manufacturer System Product Name/P8Z68-V LX, BIOS 4105 07/01/2013
[21618.982197] ffffffffa0842df0 ffff88014336b948 ffffffff8156eae1 0000000000000007
[21618.982198] ffff88014336b998 ffff88014336b988 ffffffff8105098a ffffffffa0842d5a
[21618.982199] 00000000fffffffe 0000009257a7c000 0000000000000000 ffff8803c9350000
[21618.982201] Call Trace:
[21618.982202] [<ffffffff8156eae1>] dump_stack+0x45/0x57
[21618.982203] [<ffffffff8105098a>] warn_slowpath_common+0x8a/0xc0
[21618.982204] [<ffffffff81050a06>] warn_slowpath_fmt+0x46/0x50
[21618.982208] [<ffffffffa07a5330>] __btrfs_free_extent.isra.33+0x960/0xdf0 [btrfs]
[21618.982214] [<ffffffffa080ce1d>] ? btrfs_delayed_ref_lock+0x3d/0x270 [btrfs]
[21618.982219] [<ffffffffa07a9802>] __btrfs_run_delayed_refs+0x9c2/0x1110 [btrfs]
[21618.982224] [<ffffffffa07acdb3>] btrfs_run_delayed_refs.part.38+0x73/0x280 [btrfs]
[21618.982228] [<ffffffffa07b0dbe>] btrfs_start_dirty_block_groups+0x35e/0x410 [btrfs]
[21618.982234] [<ffffffffa07c1e95>] btrfs_commit_transaction+0x1c5/0xc10 [btrfs]
[21618.982239] [<ffffffffa07c2976>] ? start_transaction+0x96/0x510 [btrfs]
[21618.982244] [<ffffffffa07bba23>] btrfs_commit_super+0x93/0xa0 [btrfs]
[21618.982248] [<ffffffffa07bd5b4>] close_ctree+0x294/0x350 [btrfs]
[21618.982252] [<ffffffffa0790dd9>] btrfs_put_super+0x19/0x20 [btrfs]
[21618.982253] [<ffffffff8117535a>] generic_shutdown_super+0x6a/0xf0
[21618.982254] [<ffffffff81175646>] kill_anon_super+0x16/0x30
[21618.982258] [<ffffffffa07906e8>] btrfs_kill_super+0x18/0x110 [btrfs]
[21618.982259] [<ffffffff811759f9>] deactivate_locked_super+0x49/0x80
[21618.982260] [<ffffffff81175e6c>] deactivate_super+0x6c/0x80
[21618.982261] [<ffffffff81192a53>] cleanup_mnt+0x43/0xa0
[21618.982263] [<ffffffff81192b02>] __cleanup_mnt+0x12/0x20
[21618.982264] [<ffffffff8106c387>] task_work_run+0xa7/0xe0
[21618.982265] [<ffffffff81002b9d>] do_notify_resume+0x6d/0x70
[21618.982266] [<ffffffff81573d42>] int_signal+0x12/0x17
[21618.982267] ---[ end trace 0556ec192b609086 ]---
[21618.982269] BTRFS: error (device sdc1) in __btrfs_free_extent:6363: errno=-2 No such entry
[21618.982800] BTRFS info (device sdc1): forced readonly
[21618.982802] BTRFS: error (device sdc1) in btrfs_run_delayed_refs:2863: errno=-2 No such entry
[21618.983332] BTRFS error (device sdc1): commit super ret -2
[21618.983407] BTRFS error (device sdc1): cleaner transaction attach returned -30
Sorry..
-h
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