Also, I am having trouble reproducing the problem. Any chance that you can help make a testcase?
I made a 5G disk, made a PV, VG and LV, and then made a btrfs filesystem. But I could never get the udev trigger to actually occur to rename the device links. Any ideas? $ uname -rv 5.15.0-127-generic #137-Ubuntu SMP Fri Nov 8 15:21:01 UTC 2024 $ lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS vda 252:0 0 10G 0 disk ├─vda1 252:1 0 9.9G 0 part / ├─vda14 252:14 0 4M 0 part └─vda15 252:15 0 106M 0 part /boot/efi vdb 252:16 0 372K 0 disk vdc 252:32 0 5G 0 disk $ sudo pvcreate /dev/vdc Physical volume "/dev/vdc" successfully created. $ sudo vgcreate vdc /dev/vdc /dev/vdc: already exists in filesystem Run `vgcreate --help' for more information. $ sudo vgcreate VG0 /dev/vdc Volume group "VG0" successfully created $ sudo lvcreate -L5G^Cn data0 vg0 $ sudo lvcreate -n LV0 -l 100%FREE VG0 Logical volume "LV0" created. $ sudo mkfs.btrfs /dev/VG0/LV0 btrfs-progs v5.16.2 See http://btrfs.wiki.kernel.org for more information. Performing full device TRIM /dev/VG0/LV0 (5.00GiB) ... NOTE: several default settings have changed in version 5.15, please make sure this does not affect your deployments: - DUP for metadata (-m dup) - enabled no-holes (-O no-holes) - enabled free-space-tree (-R free-space-tree) Label: (null) UUID: ff124bfe-c58d-4112-8b37-6466e1ddedc9 Node size: 16384 Sector size: 4096 Filesystem size: 5.00GiB Block group profiles: Data: single 8.00MiB Metadata: DUP 256.00MiB System: DUP 8.00MiB SSD detected: no Zoned device: no Incompat features: extref, skinny-metadata, no-holes Runtime features: free-space-tree Checksum: crc32c Number of devices: 1 Devices: ID SIZE PATH 1 5.00GiB /dev/VG0/LV0 $ sudo mount /dev/VG0/LV0 /m^C $ sudo mkdir /mnt/a $ sudo mkdir /mnt/b $ sudo mkdir /mnt/c $ sudo mount /dev/VG0/LV0 /mnt/a $ sudo mount /dev/VG0/LV0 /mnt/b $ sudo mount /dev/VG0/LV0 /mnt/c $ lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS loop0 7:0 0 63.7M 1 loop /snap/core20/2434 loop1 7:1 0 89.4M 1 loop /snap/lxd/31333 loop2 7:2 0 44.3M 1 loop /snap/snapd/23258 vda 252:0 0 10G 0 disk ├─vda1 252:1 0 9.9G 0 part / ├─vda14 252:14 0 4M 0 part └─vda15 252:15 0 106M 0 part /boot/efi vdb 252:16 0 372K 0 disk vdc 252:32 0 5G 0 disk └─VG0-LV0 253:0 0 5G 0 lvm /mnt/c /mnt/b /mnt/a $ grep /mnt /proc/mounts /dev/mapper/VG0-LV0 /mnt/a btrfs rw,relatime,space_cache=v2,subvolid=5,subvol=/ 0 0 /dev/mapper/VG0-LV0 /mnt/b btrfs rw,relatime,space_cache=v2,subvolid=5,subvol=/ 0 0 /dev/mapper/VG0-LV0 /mnt/c btrfs rw,relatime,space_cache=v2,subvolid=5,subvol=/ 0 0 $ sudo apt install linux-image-5.15.0-136-generic linux- modules-5.15.0-136-generic linux-modules-extra-5.15.0-136-generic linux- headers-5.15.0-136-generic $ uname -rv 5.15.0-136-generic #147-Ubuntu SMP Sat Mar 15 15:53:30 UTC 2025 $ ls /mnt a b c $ sudo mount /dev/VG0/LV0 /mnt/a $ sudo mount /dev/VG0/LV0 /mnt/b $ sudo mount /dev/VG0/LV0 /mnt/c $ lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS loop0 7:0 0 63.7M 1 loop /snap/core20/2434 loop1 7:1 0 89.4M 1 loop /snap/lxd/31333 loop2 7:2 0 44.3M 1 loop /snap/snapd/23258 vda 252:0 0 10G 0 disk ├─vda1 252:1 0 9.9G 0 part / ├─vda14 252:14 0 4M 0 part └─vda15 252:15 0 106M 0 part /boot/efi vdb 252:16 0 372K 0 disk vdc 252:32 0 5G 0 disk └─VG0-LV0 253:0 0 5G 0 lvm /mnt/c /mnt/b /mnt/a $ grep /mnt /proc/mounts /dev/mapper/VG0-LV0 /mnt/a btrfs rw,relatime,space_cache=v2,subvolid=5,subvol=/ 0 0 /dev/mapper/VG0-LV0 /mnt/b btrfs rw,relatime,space_cache=v2,subvolid=5,subvol=/ 0 0 /dev/mapper/VG0-LV0 /mnt/c btrfs rw,relatime,space_cache=v2,subvolid=5,subvol=/ 0 0 $ sudo touch /dev/mapper/VG0-LV0 $ grep /mnt /proc/mounts /dev/mapper/VG0-LV0 /mnt/a btrfs rw,relatime,space_cache=v2,subvolid=5,subvol=/ 0 0 /dev/mapper/VG0-LV0 /mnt/b btrfs rw,relatime,space_cache=v2,subvolid=5,subvol=/ 0 0 /dev/mapper/VG0-LV0 /mnt/c btrfs rw,relatime,space_cache=v2,subvolid=5,subvol=/ 0 0 $ sudo umount /mnt/a $ sudo umount /mnt/b $ sudo umount /mnt/c $ sudo mount /dev/dm-0 /mnt/a $ sudo mount /dev/dm-0 /mnt/b $ sudo mount /dev/dm-0 /mnt/c $ lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS loop0 7:0 0 63.7M 1 loop /snap/core20/2434 loop1 7:1 0 89.4M 1 loop /snap/lxd/31333 loop2 7:2 0 44.3M 1 loop /snap/snapd/23258 vda 252:0 0 10G 0 disk ├─vda1 252:1 0 9.9G 0 part / ├─vda14 252:14 0 4M 0 part └─vda15 252:15 0 106M 0 part /boot/efi vdb 252:16 0 372K 0 disk vdc 252:32 0 5G 0 disk └─VG0-LV0 253:0 0 5G 0 lvm /mnt/c /mnt/b /mnt/a $ grep /mnt /proc/mounts /dev/mapper/VG0-LV0 /mnt/a btrfs rw,relatime,space_cache=v2,subvolid=5,subvol=/ 0 0 /dev/mapper/VG0-LV0 /mnt/b btrfs rw,relatime,space_cache=v2,subvolid=5,subvol=/ 0 0 /dev/mapper/VG0-LV0 /mnt/c btrfs rw,relatime,space_cache=v2,subvolid=5,subvol=/ 0 0 $ sudo udevadm control --reload-rules $ sudo udevadm trigger $ grep /mnt /proc/mounts /dev/mapper/VG0-LV0 /mnt/a btrfs rw,relatime,space_cache=v2,subvolid=5,subvol=/ 0 0 /dev/mapper/VG0-LV0 /mnt/b btrfs rw,relatime,space_cache=v2,subvolid=5,subvol=/ 0 0 /dev/mapper/VG0-LV0 /mnt/c btrfs rw,relatime,space_cache=v2,subvolid=5,subvol=/ 0 0 $ sudo -s root@test-disk:/home/ubuntu# echo change > /sys/block/dm-0/uevent root@test-disk:/home/ubuntu# exit $ grep /mnt /proc/mounts /dev/mapper/VG0-LV0 /mnt/a btrfs rw,relatime,space_cache=v2,subvolid=5,subvol=/ 0 0 /dev/mapper/VG0-LV0 /mnt/b btrfs rw,relatime,space_cache=v2,subvolid=5,subvol=/ 0 0 /dev/mapper/VG0-LV0 /mnt/c btrfs rw,relatime,space_cache=v2,subvolid=5,subvol=/ 0 0 -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/2107516 Title: Ubuntu 22.04 kernel 5.15.0.136 changes /proc/mounts for btfs volumes Status in linux package in Ubuntu: New Status in linux source package in Jammy: New Bug description: We mount btrfs volumes, and we are seeing a change in behavior from the 5.15.0-126 kernel to 5.15.0.136 In the old behavior (existing for as long as we have had the product), mounting a btrfs lvm results in: $: grep /DataStore0 /proc/mounts /dev/mapper/VG0-LV0 /DataStore0 btrfs rw,seclabel,relatime,space_cache=v2,subvolid=5,subvol=/ 0 0 however same mount with the new kernel results in a different output: $: grep /DataStore0 /proc/mounts /dev/VG0/LV0 /DataStore0 btrfs rw,seclabel,relatime,space_cache=v2,subvolid=5,subvol=/ 0 0 (notice the /dev/VG0/LV0 vs. /dev/mapper/VG0-LV0) for the same mount. Our application code uses /dev/mapper checking extensively and we would like to avoid a rewrite if possible. Online searches bring me to this bug: https://bugs.gentoo.org/947126 which seems very similar We have this change as part of the new kernel: $:git log --oneline --grep "btrfs: avoid unnecessary device path update for the same device" Ubuntu-5.15.0-126.136..Ubuntu-5.15.0-136.147 fc83c00ca63b btrfs: avoid unnecessary device path update for the same device https://lore.kernel.org/linux- btrfs/30aefd8b4e8c1f0c5051630b106a1ff3570d28ed.1735537399.git....@suse.com/T/#u seems like a fix , I don't see this accepted yet though. If we could either revert this change or provide guidance how we should be reading this file that would be great. Thank you. 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