Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932697AbcLIJrK (ORCPT ); Fri, 9 Dec 2016 04:47:10 -0500 Received: from smtp2.provo.novell.com ([137.65.250.81]:45284 "EHLO smtp2.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752228AbcLIJrH (ORCPT ); Fri, 9 Dec 2016 04:47:07 -0500 Subject: Re: [PATCH] ocfs2: fix crash caused by stale lvb with fsdlm plugin To: ocfs2-devel@oss.oracle.com References: <1481275475-6429-1-git-send-email-zren@suse.com> Cc: akpm@linux-foundation.org, jlbec@evilplan.org, teigland@redhat.com, ghe@suse.com, junxiao.bi@oracle.com, jiangqi903@gmail.com, linux-kernel@vger.kernel.org From: Eric Ren Message-ID: Date: Fri, 9 Dec 2016 17:45:39 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: <1481275475-6429-1-git-send-email-zren@suse.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 9033 Lines: 179 Sorry, this email is not delivered to Mark successfully because of one weird character trailing his email address somehow. So, resend later... Thanks, Eric On 12/09/2016 05:24 PM, Eric Ren wrote: > The crash happens rather often when we reset some cluster > nodes while nodes contend fiercely to do truncate and append. > > The crash backtrace is below: > " > [ 245.197849] dlm: C21CBDA5E0774F4BA5A9D4F317717495: dlm_recover_grant 1 locks on 971 resources > [ 245.197859] dlm: C21CBDA5E0774F4BA5A9D4F317717495: dlm_recover 9 generation 5 done: 4 ms > [ 245.198379] ocfs2: Begin replay journal (node 318952601, slot 2) on device (253,18) > [ 247.272338] ocfs2: End replay journal (node 318952601, slot 2) on device (253,18) > [ 247.547084] ocfs2: Beginning quota recovery on device (253,18) for slot 2 > [ 247.683263] ocfs2: Finishing quota recovery on device (253,18) for slot 2 > [ 247.833022] (truncate,30154,1):ocfs2_truncate_file:470 ERROR: bug expression: le64_to_cpu(fe->i_size) != i_size_read(inode) > [ 247.833029] (truncate,30154,1):ocfs2_truncate_file:470 ERROR: Inode 290321, inode i_size = 732 != di i_size = 937, i_flags = 0x1 > [ 247.833074] ------------[ cut here ]------------ > [ 247.833077] kernel BUG at /usr/src/linux/fs/ocfs2/file.c:470! > [ 247.833079] invalid opcode: 0000 [#1] SMP > [ 247.833081] Modules linked in: ocfs2_stack_user(OEN) ocfs2(OEN) ocfs2_nodemanager ocfs2_stackglue(OEN) quota_tree dlm(OEN) configfs fuse sd_mod iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi af_packet iscsi_ibft iscsi_boot_sysfs softdog xfs libcrc32c ppdev parport_pc pcspkr parport joydev virtio_balloon virtio_net i2c_piix4 acpi_cpufreq button processor ext4 crc16 jbd2 mbcache ata_generic cirrus virtio_blk ata_piix drm_kms_helper ahci syscopyarea libahci sysfillrect sysimgblt fb_sys_fops ttm floppy libata drm virtio_pci virtio_ring uhci_hcd virtio ehci_hcd usbcore serio_raw usb_common sg dm_multipath dm_mod scsi_dh_rdac scsi_dh_emc scsi_dh_alua scsi_mod autofs4 > [ 247.833107] Supported: No, Unsupported modules are loaded > [ 247.833110] CPU: 1 PID: 30154 Comm: truncate Tainted: G OE N 4.4.21-69-default #1 > [ 247.833111] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.8.1-0-g4adadbd-20151112_172657-sheep25 04/01/2014 > [ 247.833112] task: ffff88004ff6d240 ti: ffff880074e68000 task.ti: ffff880074e68000 > [ 247.833113] RIP: 0010:[] [] ocfs2_truncate_file+0x640/0x6c0 [ocfs2] > [ 247.833151] RSP: 0018:ffff880074e6bd50 EFLAGS: 00010282 > [ 247.833152] RAX: 0000000000000074 RBX: 000000000000029e RCX: 0000000000000000 > [ 247.833153] RDX: 0000000000000001 RSI: 0000000000000246 RDI: 0000000000000246 > [ 247.833154] RBP: ffff880074e6bda8 R08: 000000003675dc7a R09: ffffffff82013414 > [ 247.833155] R10: 0000000000034c50 R11: 0000000000000000 R12: ffff88003aab3448 > [ 247.833156] R13: 00000000000002dc R14: 0000000000046e11 R15: 0000000000000020 > [ 247.833157] FS: 00007f839f965700(0000) GS:ffff88007fc80000(0000) knlGS:0000000000000000 > [ 247.833158] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b > [ 247.833159] CR2: 00007f839f97e000 CR3: 0000000036723000 CR4: 00000000000006e0 > [ 247.833164] Stack: > [ 247.833165] 00000000000003a9 0000000000000001 ffff880060554000 ffff88004fcaf000 > [ 247.833167] ffff88003aa7b090 1000000000000000 ffff88003aab3448 ffff880074e6beb0 > [ 247.833169] 0000000000000001 0000000000002068 0000000000000020 0000000000000000 > [ 247.833171] Call Trace: > [ 247.833208] [] ocfs2_setattr+0x698/0xa90 [ocfs2] > [ 247.833225] [] notify_change+0x1ae/0x380 > [ 247.833242] [] do_truncate+0x5e/0x90 > [ 247.833246] [] do_sys_ftruncate.constprop.11+0x108/0x160 > [ 247.833257] [] entry_SYSCALL_64_fastpath+0x12/0x6d > [ 247.834724] DWARF2 unwinder stuck at entry_SYSCALL_64_fastpath+0x12/0x6d > [ 247.834725] > [ 247.834726] Leftover inexact backtrace: > > [ 247.834728] Code: 24 28 ba d6 01 00 00 48 c7 c6 30 43 62 a0 8b 41 2c 89 44 24 08 48 8b 41 20 48 c7 c1 78 a3 62 a0 48 89 04 24 31 c0 e8 a0 97 f9 ff <0f> 0b 3d 00 fe ff ff 0f 84 ab fd ff ff 83 f8 fc 0f 84 a2 fd ff > [ 247.834748] RIP [] ocfs2_truncate_file+0x640/0x6c0 [ocfs2] > [ 247.834774] RSP > " > > It's because ocfs2_inode_lock() get us stale LVB in which the i_size is not > equal to the disk i_size. We mistakenly trust the LVB because the underlaying > fsdlm dlm_lock() doesn't set lkb_sbflags with DLM_SBF_VALNOTVALID properly for > us. But, why? > > The current code tries to downconvert lock without DLM_LKF_VALBLK > flag to tell o2cb don't update RSB's LVB if it's a PR->NULL conversion, > even if the lock resource type needs LVB. This is not the right way for fsdlm. > > The fsdlm plugin behaves different on DLM_LKF_VALBLK, it depends on > DLM_LKF_VALBLK to decide if we care about the LVB in the LKB. If DLM_LKF_VALBLK > is not set, fsdlm will skip recovering RSB's LVB from this lkb and set the right > DLM_SBF_VALNOTVALID appropriately when node failure happens. > > The following diagram briefly illustrates how this crash happens: > > RSB1 is inode metadata lock resource with LOCK_TYPE_USES_LVB; > > The 1st round: > > Node1 Node2 > RSB1: PR > RSB1(master): NULL->EX > ocfs2_downconvert_lock(PR->NULL, set_lvb==0) > ocfs2_dlm_lock(no DLM_LKF_VALBLK) > > - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - > > dlm_lock(no DLM_LKF_VALBLK) > convert_lock(overwrite lkb->lkb_exflags > with no DLM_LKF_VALBLK) > > RSB1: NULL RSB1: EX > reset Node2 > dlm_recover_rsbs() > recover_lvb() > > /* The LVB is not trustable if the node with EX fails and > * no lock >= PR is left. We should set RSB_VALNOTVALID for RSB1. > */ > > if(!(kb_exflags & DLM_LKF_VALBLK)) /* This means we miss the chance to > return; * to invalid the LVB here. > */ > > The 2nd round: > > Node 1 Node2 > RSB1(become master from recovery) > > ocfs2_setattr() > ocfs2_inode_lock(NULL->EX) > /* dlm_lock() return the stale lvb without setting DLM_SBF_VALNOTVALID */ > ocfs2_meta_lvb_is_trustable() return 1 /* so we don't refresh inode from disk */ > ocfs2_truncate_file() > mlog_bug_on_msg(disk isize != i_size_read(inode)) /* crash! */ > > The fix is quite straightforward. We keep to set DLM_LKF_VALBLK flag for dlm_lock() > if the lock resource type needs LVB and the fsdlm plugin is uesed. > > Signed-off-by: Eric Ren > --- > fs/ocfs2/dlmglue.c | 10 ++++++++++ > fs/ocfs2/stackglue.c | 6 ++++++ > fs/ocfs2/stackglue.h | 3 +++ > 3 files changed, 19 insertions(+) > > diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c > index 83d576f..77d1632 100644 > --- a/fs/ocfs2/dlmglue.c > +++ b/fs/ocfs2/dlmglue.c > @@ -3303,6 +3303,16 @@ static int ocfs2_downconvert_lock(struct ocfs2_super *osb, > mlog(ML_BASTS, "lockres %s, level %d => %d\n", lockres->l_name, > lockres->l_level, new_level); > > + /* > + * On DLM_LKF_VALBLK, fsdlm behaves differently with o2cb. It always > + * expects DLM_LKF_VALBLK being set if the LKB has LVB, so that > + * we can recover correctly from node failure. Otherwise, we may get > + * invalid LVB in LKB, but without DLM_SBF_VALNOTVALID being set. > + */ > + if (!ocfs2_is_o2cb_active() && > + lockres->l_ops->flags & LOCK_TYPE_USES_LVB) > + lvb = 1; > + > if (lvb) > dlm_flags |= DLM_LKF_VALBLK; > > diff --git a/fs/ocfs2/stackglue.c b/fs/ocfs2/stackglue.c > index 52c07346b..8203590 100644 > --- a/fs/ocfs2/stackglue.c > +++ b/fs/ocfs2/stackglue.c > @@ -48,6 +48,12 @@ static char ocfs2_hb_ctl_path[OCFS2_MAX_HB_CTL_PATH] = "/sbin/ocfs2_hb_ctl"; > */ > static struct ocfs2_stack_plugin *active_stack; > > +inline int ocfs2_is_o2cb_active(void) > +{ > + return !strcmp(active_stack->sp_name, OCFS2_STACK_PLUGIN_O2CB); > +} > +EXPORT_SYMBOL_GPL(ocfs2_is_o2cb_active); > + > static struct ocfs2_stack_plugin *ocfs2_stack_lookup(const char *name) > { > struct ocfs2_stack_plugin *p; > diff --git a/fs/ocfs2/stackglue.h b/fs/ocfs2/stackglue.h > index f2dce10..e3036e1 100644 > --- a/fs/ocfs2/stackglue.h > +++ b/fs/ocfs2/stackglue.h > @@ -298,6 +298,9 @@ void ocfs2_stack_glue_set_max_proto_version(struct ocfs2_protocol_version *max_p > int ocfs2_stack_glue_register(struct ocfs2_stack_plugin *plugin); > void ocfs2_stack_glue_unregister(struct ocfs2_stack_plugin *plugin); > > +/* In ocfs2_downconvert_lock(), we need to know which stack we are using */ > +int ocfs2_is_o2cb_active(void); > + > extern struct kset *ocfs2_kset; > > #endif /* STACKGLUE_H */