[linux-lvm] issue about return value in _lvchange_activate_single
heming.zhao at suse.com
heming.zhao at suse.com
Tue Nov 17 03:52:28 UTC 2020
Hello List, David & Zdenek,
I met a boring problem when executing lvchange cmd.
In lvm tools/errors.h, there are defines return values:
```
#define ECMD_PROCESSED 1
#define ENO_SUCH_CMD 2
#define EINVALID_CMD_LINE 3
#define EINIT_FAILED 4
#define ECMD_FAILED 5
```
In lvm functions, it treats "return 0" as error case.
if _lvchange_activate() return ECMD_FAILED, the caller _lvchange_activate_single() think as normal:
```
if (!_lvchange_activate(cmd, lv)) <== ECMD_FAILED is 5, won't enter if case.
return_ECMD_FAILED;
return ECMD_PROCESSED;
```
So in special condition, lvchange cmd will return successfully but cmd executing failed.
the code should be changed to:
```
diff --git a/tools/lvchange.c b/tools/lvchange.c
index f9a0b54e3..ae626a05b 100644
--- a/tools/lvchange.c
+++ b/tools/lvchange.c
@@ -1437,6 +1437,7 @@ static int _lvchange_activate_single(struct cmd_context *cmd,
{
struct logical_volume *origin;
char snaps_msg[128];
+ int rv;
/* FIXME: untangle the proper logic for cow / sparse / virtual origin */
@@ -1465,8 +1466,10 @@ static int _lvchange_activate_single(struct cmd_context *cmd,
}
}
- if (!_lvchange_activate(cmd, lv))
+ rv = _lvchange_activate(cmd, lv);
+ if (!rv || rv>1) {
return_ECMD_FAILED;
+ }
return ECMD_PROCESSED;
}
```
maybe the same problem exist in other places of lvm2 source code.
how to trigger:
there is two nodes env, node1 & node2. they share 1 iSCSI lun disk.
node1 & node2 use systemid to control the shared disk.
1. node1 already use uname to set up systemid.
```
[tb-clustermd1 ~]# pvs --foreign
PV VG Fmt Attr PSize PFree
/dev/sda vg1 lvm2 a-- 292.00m 260.00m
[tb-clustermd1 ~]# vgs --foreign -o+systemid
VG #PV #LV #SN Attr VSize VFree System ID
vg1 1 1 0 wz--n- 292.00m 260.00m tb-clustermd1
[tb-clustermd1 ~]# lvs --foreign -o+Host
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert Host
lv1 vg1 -wi-a----- 32.00m tb-clustermd1
[tb-clustermd1 ~]# dmsetup ls
vg1-lv1 (254:0)
[tb-clustermd1 ~]#
```
2. node2 change the systemid to itself
```
[tb-clustermd2 ~]# vgchange -y --config "local/extra_system_ids='tb-clustermd1'" --systemid tb-clustermd2 vg1
Volume group "vg1" successfully changed
[tb-clustermd2 ~]# lvchange -ay vg1/lv1
[tb-clustermd2 ~]# dmsetup ls
vg1-lv1 (254:0)
[tb-clustermd2 ~]#
```
3. this time both sides have dm device.
```
[tb-clustermd1 ~]# dmsetup ls
vg1-lv1 (254:0)
[tb-clustermd2 ~]# dmsetup ls
vg1-lv1 (254:0)
```
4. node1 executes lvchange cmds. please note the return value is 0
```
[tb-clustermd1 ~]# lvchange -ay vg1/lv1 ; echo $?
WARNING: Found LVs active in VG vg1 with foreign system ID tb-clustermd2. Possible data corruption.
Cannot activate LVs in a foreign VG.
0
[tb-clustermd1 ~]# dmsetup ls
vg1-lv1 (254:0)
[tb-clustermd1 ~]# lvchange -an vg1/lv1 ; echo $?
WARNING: Found LVs active in VG vg1 with foreign system ID tb-clustermd2. Possible data corruption.
0
[tb-clustermd1 ~]# dmsetup ls
No devices found
[tb-clustermd1 ~]#
```
Thanks.
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