udev: rename the persistent link for ATA devices

System Internals / systemd - Lidong Zhong [suse.com] - 21 May 2020 07:58 EDT

ATA devices should use the ATA ids like port number and (possibly) master/slave or multiplier id, not the generic SCSI ID. Currently only port number is included in the link. With this patch the link would be able to support more cases, which are a) when the device is behind a port multiplexer b) the distinction between master and slave (distinguished by target id).

I tried to verify scenario a) with this patch, but I failed to find a machine with PMP SATA devices attached. But the link below https://github.com/systemd/systemd/issues/3943 could show what's the difference. Here is my test for scenario b)

Current version: linux-ql21:~ # ll /sys/class/block/sd[ab] lrwxrwxrwx 1 root root 0 May 8 20:46 /sys/class/block/sda -> ../../devices/pci0000:00/0000:00:01.1/ata4/host3/target3:0:0/3:0:0:0/block/sda lrwxrwxrwx 1 root root 0 May 8 20:46 /sys/class/block/sdb -> ../../devices/pci0000:00/0000:00:01.1/ata4/host3/target3:0:1/3:0:1:0/block/sdb linux-ql21:~ # ll /dev/disk/by-path/pci-0000\:00\:01.1-ata-1 lrwxrwxrwx 1 root root 9 May 8 20:44 /dev/disk/by-path/pci-0000:00:01.1-ata-1 -> ../../sdb linux-ql21:~ # udevadm info /sys/class/block/sda |grep by-path S: disk/by-path/pci-0000:00:01.1-ata-1 E: DEVLINKS=/dev/disk/by-id/ata-VBOX_HARDDISK_VB3649e885-3e0cdd64 /dev/disk/by-id/scsi-0ATA_VBOX_HARDDISK_VB3649e885-3e0cdd64 /dev/disk/by-id/scsi-1ATA_VBOX_HARDDISK_VB3649e885-3e0cdd64 /dev/disk/by-path/pci-0000:00:01.1-ata-1 /dev/disk/by-id/scsi-SATA_VBOX_HARDDISK_VB3649e885-3e0cdd64 linux-ql21:~ # udevadm info /sys/class/block/sdb |grep by-path S: disk/by-path/pci-0000:00:01.1-ata-1 E: DEVLINKS=/dev/disk/by-id/ata-VBOX_HARDDISK_VBc53b2498-d84ae8de /dev/disk/by-id/scsi-SATA_VBOX_HARDDISK_VBc53b2498-d84ae8de /dev/disk/by-id/scsi-1ATA_VBOX_HARDDISK_VBc53b2498-d84ae8de /dev/disk/by-id/scsi-0ATA_VBOX_HARDDISK_VBc53b2498-d84ae8de /dev/disk/by-path/pci-0000:00:01.1-ata-1

After patch applied: linux-ql21:~ # ll /sys/class/block/sd[ab] lrwxrwxrwx 1 root root 0 May 8 21:07 /sys/class/block/sda -> ../../devices/pci0000:00/0000:00:01.1/ata4/host3/target3:0:0/3:0:0:0/block/sda lrwxrwxrwx 1 root root 0 May 8 21:07 /sys/class/block/sdb -> ../../devices/pci0000:00/0000:00:01.1/ata4/host3/target3:0:1/3:0:1:0/block/sdb linux-ql21:~ # ll /dev/disk/by-path/pci-0000\:00\:01.1-ata-* lrwxrwxrwx 1 root root 9 May 8 21:07 /dev/disk/by-path/pci-0000:00:01.1-ata-1.0 -> ../../sda lrwxrwxrwx 1 root root 9 May 8 21:07 /dev/disk/by-path/pci-0000:00:01.1-ata-1.1 -> ../../sdb linux-ql21:~ # udevadm info /sys/class/block/sda |grep by-path S: disk/by-path/pci-0000:00:01.1-ata-1.0 E: DEVLINKS=/dev/disk/by-id/scsi-1ATA_VBOX_HARDDISK_VB3649e885-3e0cdd64 /dev/disk/by-id/scsi-0ATA_VBOX_HARDDISK_VB3649e885-3e0cdd64 /dev/disk/by-id/ata-VBOX_HARDDISK_VB3649e885-3e0cdd64 /dev/disk/by-path/pci-0000:00:01.1-ata-1.0 /dev/disk/by-id/scsi-SATA_VBOX_HARDDISK_VB3649e885-3e0cdd64 linux-ql21:~ # udevadm info /sys/class/block/sdb |grep by-path S: disk/by-path/pci-0000:00:01.1-ata-1.1 E: DEVLINKS=/dev/disk/by-id/scsi-0ATA_VBOX_HARDDISK_VBc53b2498-d84ae8de /dev/disk/by-id/ata-VBOX_HARDDISK_VBc53b2498-d84ae8de /dev/disk/by-id/scsi-1ATA_VBOX_HARDDISK_VBc53b2498-d84ae8de /dev/disk/by-id/scsi-SATA_VBOX_HARDDISK_VBc53b2498-d84ae8de /dev/disk/by-path/pci-0000:00:01.1-ata-1.1

Changelog:
v5: add another parameter compat_link in handle_scsi()
v4: comment for ID_PATH_ATA_COMPAT get string length with pointer difference (suggested by Franck Bui)
v3: creating compatible link from env
variables type change
v2: remove udev rules modification for compatible link setup a test scenario of master/slave ATA devices
v1: initial patch

9b3278d907 udev: rename the persistent link for ATA devices
rules.d/60-persistent-storage.rules | 3 ++
src/udev/udev-builtin-path_id.c | 55 +++++++++++++++++++++++++++++++++----
2 files changed, 52 insertions(+), 6 deletions(-)

Upstream: github.com


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