Bug 1832157
| Summary: | fdisk fails to re-read partition table | ||||||
|---|---|---|---|---|---|---|---|
| Product: | [Fedora] Fedora | Reporter: | Dan Horák <dan> | ||||
| Component: | device-mapper-multipath | Assignee: | LVM and device-mapper development team <lvm-team> | ||||
| Status: | CLOSED NOTABUG | QA Contact: | Fedora Extras Quality Assurance <extras-qa> | ||||
| Severity: | unspecified | Docs Contact: | |||||
| Priority: | unspecified | ||||||
| Version: | rawhide | CC: | agk, bmarzins, cfeist, hannsj_uhl, heinzm, jonathan, kzak, lvm-team, mcsontos, msnitzer, prajnoha, prockai | ||||
| Target Milestone: | --- | ||||||
| Target Release: | --- | ||||||
| Hardware: | s390x | ||||||
| OS: | Unspecified | ||||||
| Whiteboard: | |||||||
| Fixed In Version: | Doc Type: | If docs needed, set a value | |||||
| Doc Text: | Story Points: | --- | |||||
| Clone Of: | Environment: | ||||||
| Last Closed: | 2020-05-07 07:15:09 UTC | Type: | Bug | ||||
| Regression: | --- | Mount Type: | --- | ||||
| Documentation: | --- | CRM: | |||||
| Verified Versions: | Category: | --- | |||||
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |||||
| Cloudforms Team: | --- | Target Upstream Version: | |||||
| Embargoed: | |||||||
| Bug Depends On: | |||||||
| Bug Blocks: | 467765 | ||||||
| Attachments: |
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Strange.
libfdisk uses BLKRRPART to detect if the device is used, it ends with error:
ioctl(3, BLKRRPART) = -1 EINVAL (Invalid argument)
then after partition table modification it uses BLKPG_{ADD,RESIZE,DEL}_PARTITION ioctls to inform the system about changes. These ioctls fail too:
ioctl(3, BLKPG, {op=BLKPG_ADD_PARTITION, flags=0, datalen=152, data={start=1048576, length=104857600, pno=1, devname="", volname=""}}) = -1 EINVAL (Invalid argument)
The most strange is that after all these failed syscalls the partition has been added to the system
# lsblk /dev/mapper/mpathb
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
mpathb 253:1 0 20G 0 mpath
└─mpathb1 253:8 0 100M 0 part
(tried with 100MiB partition after reboot).
And now the craziest thing -- if I use "sfdisk --no-tell-kernel --no-reread" to avoid these ioctls than the partition node is still created.
# echo ',200MiB,L' | sfdisk --append --no-tell-kernel --no-reread /dev/mapper/mpathb
...
Disklabel type: gpt
Disk identifier: 8A4F4EE2-C34F-E543-88DC-09ACC9C1A39C
Old situation:
Device Start End Sectors Size Type
/dev/mapper/mpathb1 2048 411647 409600 200M Linux filesystem
/dev/mapper/mpathb2 411648 821247 409600 200M Linux filesystem
New situation:
Device Start End Sectors Size Type
/dev/mapper/mpathb1 2048 411647 409600 200M Linux filesystem
/dev/mapper/mpathb2 411648 821247 409600 200M Linux filesystem
/dev/mapper/mpathb-part3 821248 1230847 409600 200M Linux filesystem
The partition table has been altered.
kernel's point of view:
# lsblk /dev/mapper/mpathb
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
mpathb 253:1 0 20G 0 mpath
├─mpathb1 253:8 0 200M 0 part
├─mpathb2 253:9 0 200M 0 part
└─mpathb3 253:10 0 200M 0 part
Note, this is not standard behavior on other devices. It seems like mpath (or HW behind it) automatically creates partition nodes. There is nothing in dmesg(1)/journal output.
Reassigning to multipath guys. There are no true partitions for device-mapper devices. They are instead linear-type device-mapper devices that are created by kpartx with a special UUID that marks them as "partitions" of another device-mapper device. These are automatically created for multipath devices. When a multipath device is first created or whenever it gets a uevent that wasn't triggered by device-mapper itself. there is a udev rule (/lib/udev/rules.d/66-kpartx.rules) that will run kpartx to update the partition devices associated with the multipath device. If you use parted instead of fdisk, it understands device-mapper devices, and will automatically create the partition devices itself, instead of throwing an error. fdisk could do the same thing. But as long a uevent gets sent, kpartx should reload the partitions. So, what's the bug here? Are you wanting the multipath device to not have its partitions updated? OK, thanks for the information. It would be nice to have somewhere any log message, but it's nothing important. Closing. |
Created attachment 1685599 [details] strace log Adding new partition on a multipathed zFCP disk with fdisk fails. I believe I saw same issue after cleaning partitions with wipefs. [root@rock-kvmlp-fedora ~]# strace -o /tmp/fdisk.log fdisk /dev/mapper/mpathb Welcome to fdisk (util-linux 2.35.1). Changes will remain in memory only, until you decide to write them. Be careful before using the write command. Device does not contain a recognized partition table. Created a new DOS disklabel with disk identifier 0xe3106171. Command (m for help): n Partition type p primary (0 primary, 0 extended, 4 free) e extended (container for logical partitions) Select (default p): p Partition number (1-4, default 1): First sector (2048-41943039, default 2048): Last sector, +/-sectors or +/-size{K,M,G,T,P} (2048-41943039, default 41943039): Created a new partition 1 of type 'Linux' and of size 20 GiB. Command (m for help): w The partition table has been altered. Failed to add partition 1 to system: Invalid argument The kernel still uses the old partitions. The new table will be used at the next reboot. Syncing disks. [root@rock-kvmlp-fedora ~]# lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda 8:0 0 100G 0 disk └─mpatha 253:0 0 100G 0 mpath ├─mpatha1 253:3 0 1G 0 part /boot └─mpatha2 253:4 0 99G 0 part ├─fedora_rock--kvmlp--fedora-root 253:5 0 61.2G 0 lvm / ├─fedora_rock--kvmlp--fedora-swap 253:6 0 8G 0 lvm [SWAP] └─fedora_rock--kvmlp--fedora-home 253:7 0 29.9G 0 lvm /home sdb 8:16 0 20G 0 disk └─mpathb 253:1 0 20G 0 mpath └─mpathb1 253:8 0 20G 0 part sdc 8:32 0 20G 0 disk └─mpathc 253:2 0 20G 0 mpath sdd 8:48 0 100G 0 disk └─mpatha 253:0 0 100G 0 mpath ├─mpatha1 253:3 0 1G 0 part /boot └─mpatha2 253:4 0 99G 0 part ├─fedora_rock--kvmlp--fedora-root 253:5 0 61.2G 0 lvm / ├─fedora_rock--kvmlp--fedora-swap 253:6 0 8G 0 lvm [SWAP] └─fedora_rock--kvmlp--fedora-home 253:7 0 29.9G 0 lvm /home sde 8:64 0 20G 0 disk └─mpathb 253:1 0 20G 0 mpath └─mpathb1 253:8 0 20G 0 part sdf 8:80 0 20G 0 disk └─mpathc 253:2 0 20G 0 mpath Version-Release number of selected component (if applicable): util-linux-2.35.1-7.fc32.s390x