For older releases such as bionic we have one event: UDEV [1304.304437] change /devices/virtual/block/bcache0 (block) .ID_FS_TYPE_NEW= ACTION=change CACHED_LABEL= CACHED_UUID=0192e0a7-9d8e-4771-9bb1-d730a2f66a9d DEVLINKS=/dev/bcache/by-uuid/0192e0a7-9d8e-4771-9bb1-d730a2f66a9d DEVNAME=/dev/bcache0 DEVPATH=/devices/virtual/block/bcache0 DEVTYPE=disk DRIVER=bcache ID_FS_TYPE= MAJOR=251 MINOR=0 SEQNUM=4384 SUBSYSTEM=block TAGS=:systemd: USEC_INITIALIZED=1304237024
that creates the expected symlink. --------- For focal, instead we get two events: UDEV [2763.370729] change /devices/virtual/block/bcache0 (block) ACTION=change DEVPATH=/devices/virtual/block/bcache0 SUBSYSTEM=block DRIVER=bcache CACHED_UUID=1522715e-a390-40db-8d47-06fb728014e5 CACHED_LABEL= DEVNAME=/dev/bcache0 DEVTYPE=disk SEQNUM=5523 USEC_INITIALIZED=2763323504 .ID_FS_TYPE_NEW= ID_FS_TYPE= MAJOR=251 MINOR=0 DEVLINKS=/dev/bcache/by-uuid/1522715e-a390-40db-8d47-06fb728014e5 TAGS=:systemd: KERNEL[2784.362374] change /devices/virtual/block/bcache0 (block) ACTION=change DEVPATH=/devices/virtual/block/bcache0 SUBSYSTEM=block SYNTH_UUID=0 DEVNAME=/dev/bcache0 DEVTYPE=disk SEQNUM=5524 MAJOR=251 MINOR=0 UDEV [2784.433618] change /devices/virtual/block/bcache0 (block) ACTION=change DEVPATH=/devices/virtual/block/bcache0 SUBSYSTEM=block SYNTH_UUID=0 DEVNAME=/dev/bcache0 DEVTYPE=disk SEQNUM=5524 USEC_INITIALIZED=2763323504 ID_FS_UUID=30b28bee-6a1e-423d-9d53-32c78ba5454a ID_FS_UUID_ENC=30b28bee-6a1e-423d-9d53-32c78ba5454a ID_FS_VERSION=1.0 ID_FS_TYPE=ext4 ID_FS_USAGE=filesystem .ID_FS_TYPE_NEW=ext4 MAJOR=251 MINOR=0 DEVLINKS=/dev/disk/by-uuid/30b28bee-6a1e-423d-9d53-32c78ba5454a TAGS=:systemd: This performs: pr 21 14:15:22 ubuntu-focal systemd-udevd[1870]: bcache0: Processing device (SEQNUM=5523, ACTION=change) Apr 21 14:15:22 ubuntu-focal systemd-udevd[1870]: bcache0: Removing watch Apr 21 14:15:22 ubuntu-focal systemd-udevd[1870]: value '[dmi/id]sys_vendor' is 'QEMU' Apr 21 14:15:22 ubuntu-focal systemd-udevd[1870]: value '[dmi/id]sys_vendor' is 'QEMU' Apr 21 14:15:22 ubuntu-focal systemd-udevd[1870]: bcache0: /usr/lib/udev/rules.d/60-persistent-storage.rules:109 Importing properties from results of builtin command 'blkid' Apr 21 14:15:22 ubuntu-focal systemd-udevd[1870]: bcache0: Probe /dev/bcache0 with raid and offset=0 Apr 21 14:15:22 ubuntu-focal systemd-udevd[1870]: bcache0: /usr/lib/udev/rules.d/69-bcache.rules:16 Importing properties from results of 'probe-bcache -o udev /dev/bcache0' Apr 21 14:15:22 ubuntu-focal systemd-udevd[1870]: bcache0: Starting 'probe-bcache -o udev /dev/bcache0' Apr 21 14:15:22 ubuntu-focal systemd-udevd[1870]: Successfully forked off '(spawn)' as PID 1912. Apr 21 14:15:22 ubuntu-focal systemd-udevd[1870]: bcache0: Process 'probe-bcache -o udev /dev/bcache0' succeeded. Apr 21 14:15:22 ubuntu-focal systemd-udevd[1870]: bcache0: /usr/lib/udev/rules.d/69-bcache.rules:27 LINK 'bcache/by-uuid/1522715e-a390-40db-8d47-06fb728014e5' Apr 21 14:15:22 ubuntu-focal systemd-udevd[1870]: bcache0: Handling device node '/dev/bcache0', devnum=b251:0 Apr 21 14:15:22 ubuntu-focal systemd-udevd[1870]: bcache0: Preserve already existing symlink '/dev/block/251:0' to '../bcache0' Apr 21 14:15:22 ubuntu-focal systemd-udevd[1870]: bcache0: Creating symlink '/dev/bcache/by-uuid/1522715e-a390-40db-8d47-06fb728014e5' to '../../bcache0' Apr 21 14:15:22 ubuntu-focal systemd-udevd[1870]: bcache0: sd-device: Created db file '/run/udev/data/b251:0' for '/devices/virtual/block/bcache0' Apr 21 14:15:22 ubuntu-focal systemd-udevd[1870]: bcache0: Adding watch on '/dev/bcache0' Apr 21 14:15:22 ubuntu-focal systemd-udevd[1870]: bcache0: sd-device: Created db file '/run/udev/data/b251:0' for '/devices/virtual/block/bcache0' Apr 21 14:15:22 ubuntu-focal systemd-udevd[1870]: bcache0: Device (SEQNUM=5523, ACTION=change) processed Apr 21 14:15:22 ubuntu-focal systemd-udevd[1870]: bcache0: sd-device-monitor: Passed 388 byte to netlink monitor followed by the extra action: Apr 21 14:15:43 ubuntu-focal systemd-udevd[1916]: bcache0: Processing device (SEQNUM=5524, ACTION=change) Apr 21 14:15:43 ubuntu-focal systemd-udevd[1916]: bcache0: Removing watch Apr 21 14:15:43 ubuntu-focal systemd-udevd[1916]: value '[dmi/id]sys_vendor' is 'QEMU' Apr 21 14:15:43 ubuntu-focal systemd-udevd[1916]: value '[dmi/id]sys_vendor' is 'QEMU' Apr 21 14:15:43 ubuntu-focal systemd-udevd[1916]: bcache0: /usr/lib/udev/rules.d/60-persistent-storage.rules:109 Importing properties from results of builtin command 'blkid' Apr 21 14:15:43 ubuntu-focal systemd-udevd[1916]: bcache0: Probe /dev/bcache0 with raid and offset=0 Apr 21 14:15:43 ubuntu-focal systemd-udevd[1916]: bcache0: /usr/lib/udev/rules.d/60-persistent-storage.rules:112 LINK 'disk/by-uuid/30b28bee-6a1e-423d-9d53-32c78ba5454a' Apr 21 14:15:43 ubuntu-focal systemd-udevd[1916]: bcache0: Updating old name, '/dev/bcache/by-uuid/1522715e-a390-40db-8d47-06fb728014e5' no longer belonging to '/devices/virtual/block/bcache0' Apr 21 14:15:43 ubuntu-focal systemd-udevd[1916]: bcache0: No reference left, removing '/dev/bcache/by-uuid/1522715e-a390-40db-8d47-06fb728014e5' Apr 21 14:15:43 ubuntu-focal systemd-udevd[1916]: bcache0: Handling device node '/dev/bcache0', devnum=b251:0 Apr 21 14:15:43 ubuntu-focal systemd-udevd[1916]: bcache0: Preserve already existing symlink '/dev/block/251:0' to '../bcache0' Apr 21 14:15:43 ubuntu-focal systemd-udevd[1916]: bcache0: Creating symlink '/dev/disk/by-uuid/30b28bee-6a1e-423d-9d53-32c78ba5454a' to '../../bcache0' Apr 21 14:15:43 ubuntu-focal systemd-udevd[1916]: bcache0: sd-device: Created db file '/run/udev/data/b251:0' for '/devices/virtual/block/bcache0' Apr 21 14:15:43 ubuntu-focal systemd-udevd[1916]: bcache0: Adding watch on '/dev/bcache0' Apr 21 14:15:43 ubuntu-focal systemd-udevd[1916]: bcache0: sd-device: Created db file '/run/udev/data/b251:0' for '/devices/virtual/block/bcache0' Apr 21 14:15:43 ubuntu-focal systemd-udevd[1916]: bcache0: Device (SEQNUM=5524, ACTION=change) processed Apr 21 14:15:43 ubuntu-focal systemd-udevd[1916]: bcache0: sd-device-monitor: Passed 471 byte to netlink monitor So it appears the symlink is being added to /dev/bcache/by- uuid/1522715e-a390-40db-8d47-06fb728014e5 and then the next udev action removes this symlink and adds dev/disk/by-uuid/30b28bee-6a1e-423d- 9d53-32c78ba5454a instead. -- 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/1729145 Title: /dev/bcache/by-uuid links not created after reboot Status in linux package in Ubuntu: Fix Released Status in linux source package in Xenial: Fix Released Status in linux source package in Zesty: Won't Fix Status in linux source package in Artful: Fix Released Status in linux source package in Bionic: Fix Released Bug description: 1. $ lsb_release -rd Description: Ubuntu 17.10 Release: 17.10 2. $ apt-cache policy linux-image-`uname -r` linux-image-4.13.0-16-generic: Installed: 4.13.0-16.19 Candidate: 4.13.0-16.19 Version table: *** 4.13.0-16.19 500 500 http://nova.clouds.archive.ubuntu.com/ubuntu artful/main amd64 Packages 100 /var/lib/dpkg/status 3. After creating some bcache devices and rebooting /dev/bcache/by-uuid/<UUID> -> ../../bcacheN symlinks point to the current bcache device which is caching the dev.uuid found after creating a backing device. 4. /dev/bcache/by-uuid does not exist and there are not symlinks underneath It appears that since the initramfs loads the bcache module which probes and finds all of the cache devices and backing devices then once the rootfs is mounted and udev gets to run, the bcache kernel module does not emit the CACHED_UUID value into the environment if the underlying devices are already registered. In dmesg, one can see that prior to mounting the rootfs, we see bcache register events: [ 5.333973] bcache: register_bdev() registered backing device vdb2 [ 5.354138] bcache: register_bdev() registered backing device vdb4 [ 5.365665] bcache: register_bdev() registered backing device vdb3 [ 5.397720] bcache: bch_journal_replay() journal replay done, 0 keys in 1 entries, seq 1 [ 5.428683] bcache: register_cache() registered cache device vdb1 then rootfs ismounted and systemd starts systemd-udev [ 9.350889] systemd[1]: Listening on udev Kernel Socket. And then the coldplug replay of kernel events triggers /lib/udev/rules.d/69-bcache.rules which invokes /lib/udev/bcache-register which writes the device name (/dev/vdb1 or /dev/bcache0) into /sys/fs/bcache/register and results is the bcache kernel driver attempting to register the block device. However, there is already a bcache device associated already and registration fails [ 11.173141] bcache: register_bcache() error opening /dev/vdb2: device already registered [ 11.184617] bcache: register_bcache() error opening /dev/vdb3: device already registered [ 11.199130] bcache: register_bcache() error opening /dev/vdb1: device already registered [ 11.271694] bcache: register_bcache() error opening /dev/vdb4: device already registered The problem then is that only a kernel call to bch_cached_dev_run() which happens like this: bcache_register() register_bdev() bch_cached_dev_run() kobject_uevent_env(&disk_to_dev(d->disk)->kobj, KOBJ_CHANGE, env); where env includes: "DRIVER=bcache", kasprintf(GFP_KERNEL, "CACHED_UUID=%pU", dc->sb.uuid), NULL, NULL, }; Since that event is not emitted for any previously registered device, then the symlink will not be created. ProblemType: Bug DistroRelease: Ubuntu 17.10 Package: linux-image-4.13.0-16-generic 4.13.0-16.19 ProcVersionSignature: User Name 4.13.0-16.19-generic 4.13.4 Uname: Linux 4.13.0-16-generic x86_64 AlsaDevices: total 0 crw-rw---- 1 root audio 116, 1 Oct 31 22:09 seq crw-rw---- 1 root audio 116, 33 Oct 31 22:09 timer AplayDevices: Error: [Errno 2] No such file or directory: 'aplay': 'aplay' ApportVersion: 2.20.7-0ubuntu3.1 Architecture: amd64 ArecordDevices: Error: [Errno 2] No such file or directory: 'arecord': 'arecord' AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1: CRDA: N/A Date: Wed Nov 1 01:39:01 2017 Ec2AMI: ami-0000030b Ec2AMIManifest: FIXME Ec2AvailabilityZone: nova Ec2InstanceType: m1.small Ec2Kernel: unavailable Ec2Ramdisk: unavailable IwConfig: Error: [Errno 2] No such file or directory: 'iwconfig': 'iwconfig' Lsusb: Bus 001 Device 002: ID 0627:0001 Adomax Technology Co., Ltd Bus 001 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub MachineType: OpenStack Foundation OpenStack Nova PciMultimedia: ProcEnviron: TERM=xterm PATH=(custom, no user) XDG_RUNTIME_DIR=<set> LANG=C.UTF-8 SHELL=/bin/bash ProcFB: ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.13.0-16-generic root=LABEL=cloudimg-rootfs ro console=tty1 console=ttyS0 RelatedPackageVersions: linux-restricted-modules-4.13.0-16-generic N/A linux-backports-modules-4.13.0-16-generic N/A linux-firmware N/A RfKill: Error: [Errno 2] No such file or directory: 'rfkill': 'rfkill' SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 04/01/2014 dmi.bios.vendor: SeaBIOS dmi.bios.version: 1.10.1-1ubuntu1~cloud0 dmi.chassis.type: 1 dmi.chassis.vendor: QEMU dmi.chassis.version: pc-i440fx-zesty dmi.modalias: dmi:bvnSeaBIOS:bvr1.10.1-1ubuntu1~cloud0:bd04/01/2014:svnOpenStackFoundation:pnOpenStackNova:pvr15.0.7:cvnQEMU:ct1:cvrpc-i440fx-zesty: dmi.product.family: Virtual Machine dmi.product.name: OpenStack Nova dmi.product.version: 15.0.7 dmi.sys.vendor: OpenStack Foundation Related bugs: * bug 1728742: [userspace] curtin dname for bcache uses unstable devname instead of UUID Edit To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1729145/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
