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Bug #17562

closed

backtrace check fails when scrubbing directory created by fsstress

Added by Zheng Yan over 7 years ago. Updated over 7 years ago.

Status:
Resolved
Priority:
Normal
Assignee:
Zheng Yan
Category:
-
Target version:
-
% Done:

0%

Source:
other
Tags:
Backport:
Regression:
No
Severity:
3 - minor
Reviewed:
Affected Versions:
ceph-qa-suite:
Component(FS):
Labels (FS):
Pull request ID:
Crash signature (v1):
Crash signature (v2):

Description

when scrubbing created by fsstress, there are lots of false backtrace errors. The bug is in inode_backtrace_t::compare. but the code is so confusing. I can't understand Greg's intention

One example of failure

[root@zhyan-desk1 mds]# ceph daemon mds.a scrub_path /fsstress/pf/d8/d62/d764/dc6d/d14b4/d20d6/d2831/d3a7f/d488/d511/d1df5/d1d00/d4821/d50b7/d1146/dc59/ repair
{
    "performed_validation": true,
    "passed_validation": false,
    "backtrace": {
        "checked": true,
        "passed": false,
        "read_ret_val": 0,
        "ondisk_value": "(269)1000000cd38:[<10000008937\/dc59 v1218>,<10000007705\/d54c v170>,<1000000723d\/d3cf v2426>,<100000051de\/d366 v2068>,<10000004b63\/db0 v4387>,<10000004b60\/d25 v3759>,<10000004a79\/d21 v4482>,<1000000002a\/d8 v2286>,<10000000000\/pf v16768>,<1\/fsstress v2348>]\/\/",
        "memoryvalue": "(269)1000000cd38:[<10000008937\/dc59 v19537>,<1000000af34\/d1146 v3524>,<10000039adc\/d50b7 v1321>,<10000019d91\/d4821 v288>,<1000000b3cc\/d1d00 v4928>,<100000086d2\/d1df5 v34596>,<100000081cd\/d511 v2529>,<10000005d8d\/d488 v28540>,<1000000947f\/d3a7f v28103>,<1000001cb01\/d2831 v19700>,<1000000a413\/d20d6 v28872>,<1000000ce1e\/d14b4 v13328>,<10000005552\/dc6d v23056>,<10000004dfd\/d764 v21852>,<10000004a79\/d62 v57237>,<1000000002a\/d8 v24004>,<10000000000\/pf v285463>,<1\/fsstress v42491>]\/\/",
        "error_str": "" 
    },
    "raw_stats": {
        "checked": true,
        "passed": true,
        "read_ret_val": 0,
        "ondisk_value.dirstat": "f(v0 m2016-10-13 17:01:16.208620 8=6+2)",
        "ondisk_value.rstat": "n(v0 rc2016-10-13 17:01:16.208620 b4457089 19=15+4)",
        "memory_value.dirrstat": "f(v0 m2016-10-13 17:01:16.208620 8=6+2)",
        "memory_value.rstat": "n(v7 rc2016-10-13 17:01:16.208620 b4457089 19=15+4)",
        "error_str": "" 
    },
    "return_code": 0
}


Breakpoint 1, inode_backtrace_t::compare (this=this@entry=0x55f3dd638c80, other=..., equivalent=equivalent@entry=0x7f08ee22690e, divergent=divergent@entry=0x7f08ee22690f)
    at /home/zhyan/Ceph/ceph-2/src/mds/inode_backtrace.cc:124
124      int min_size = MIN(ancestors.size(),other.ancestors.size());
(gdb) n
125      *divergent = false;
(gdb) 
126      if (min_size == 0)
(gdb) 
123    {
(gdb) 
129      if (ancestors[0].version > other.ancestors[0].version)
(gdb) 
130        comparator = 1;
(gdb) 
133      for (int i = 1; i < min_size; ++i) {
(gdb) 
134        if (*divergent) {
(gdb) 
141        if (ancestors[i].dirino != other.ancestors[i].dirino) {
(gdb) 
142          *equivalent = false;
(gdb) 
143          if (ancestors[i-1].version < other.ancestors[i-1].version) {
(gdb) 
147          } else if (ancestors[i-1].version > other.ancestors[i-1].version) {
(gdb) 
148            if (comparator < 0)
(gdb) 
150            return 1;
(gdb) 
168    }
(gdb) 
CInode::ValidationContinuation::_backtrace (this=0x55f3dd417ac0, rval=0) at /home/zhyan/Ceph/ceph-2/src/mds/CInode.cc:3843
3843          if (equivalent) {
(gdb) 
3846            if (divergent || memory_newer <= 0) {
(gdb) p equivalent
$1 = false
(gdb) p divergent
$2 = false
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