Gfilui

Here is what I am trying to accomplish with a udev rule. Maybe I need more than one.

I have a micro-sd card I insert into a usb adapter. This card has multiple partitions. I want to have a /dev/sdcard that points to the root of the card when it is inserted. I also want the group of the device to be set to a specific group.

So my card might have /dev/sdd, /dev/sdd1, /dev/sdd2

I want /dev/sdcard to point to /dev/sdd

Here is the rule I am currently using.

ATTRSremovable=="1",SUBSYSTEMS=="block",SYMLINK+="sdcard",GROUP="rawdisk"

I currently see the group of /dev/sdd correctly changed to rawdisk.

$ ls -la /dev/sdd
brw-rw---- 1 root rawdisk 8, 48 Apr 19 14:51 /dev/sdd

However, /dev/sdcard points to /dev/sdd2 instead of /dev/sdd

$ ls -la /dev/sdcard
lrwxrwxrwx 1 root root 4 Apr 19 14:51 /dev/sdcard -> sdd2

And removing the card does not remove /dev/sdcard

$ udevadm info --name=/dev/sdd --attribute-walk

Udevadm info starts with the device specified by the devpath and then
walks up the chain of parent devices. It prints for every device
found, all possible attributes in the udev rules key format.
A rule to match, can be composed by the attributes of the device
and the attributes from one single parent device.

 looking at device '/devices/pci0000:00/0000:00:0b.0/usb1/1-1/1-1:1.1/host4/target4:0:0/4:0:0:2/block/sdd':
 KERNEL=="sdd"
 SUBSYSTEM=="block"
 DRIVER==""
 ATTRro=="0"
 ATTRsize=="0"
 ATTRstat==" 3815 2182 44808 49392 16 0 128 2028 0 28516 51416"
 ATTRrange=="16"
 ATTRdiscard_alignment=="0"
 ATTRevents=="media_change"
 ATTRext_range=="256"
 ATTRevents_poll_msecs=="2000"
 ATTRalignment_offset=="0"
 ATTRinflight==" 0 0"
 ATTRremovable=="1"
 ATTRcapability=="51"
 ATTRevents_async==""

 looking at parent device '/devices/pci0000:00/0000:00:0b.0/usb1/1-1/1-1:1.1/host4/target4:0:0/4:0:0:2':
 KERNELS=="4:0:0:2"
 SUBSYSTEMS=="scsi"
 DRIVERS=="sd"
 ATTRSrev=="1.00"
 ATTRStype=="0"
 ATTRSscsi_level=="0"
 ATTRSmodel=="SD/MMC "
 ATTRSstate=="running"
 ATTRSqueue_type=="none"
 ATTRSiodone_cnt=="0x2ad5"
 ATTRSiorequest_cnt=="0x2ad5"
 ATTRSdevice_busy=="0"
 ATTRSevt_capacity_change_reported=="0"
 ATTRStimeout=="30"
 ATTRSevt_media_change=="0"
 ATTRSmax_sectors=="240"
 ATTRSioerr_cnt=="0xf6"
 ATTRSqueue_depth=="1"
 ATTRSvendor=="Generic-"
 ATTRSevt_soft_threshold_reached=="0"
 ATTRSdevice_blocked=="0"
 ATTRSevt_mode_parameter_change_reported=="0"
 ATTRSevt_lun_change_reported=="0"
 ATTRSevt_inquiry_change_reported=="0"
 ATTRSdh_state=="detached"
 ATTRSiocounterbits=="32"
 ATTRSinquiry==""
 ATTRSeh_timeout=="10"

 looking at parent device '/devices/pci0000:00/0000:00:0b.0/usb1/1-1/1-1:1.1/host4/target4:0:0':
 KERNELS=="target4:0:0"
 SUBSYSTEMS=="scsi"
 DRIVERS==""

 looking at parent device '/devices/pci0000:00/0000:00:0b.0/usb1/1-1/1-1:1.1/host4':
 KERNELS=="host4"
 SUBSYSTEMS=="scsi"
 DRIVERS==""

 looking at parent device '/devices/pci0000:00/0000:00:0b.0/usb1/1-1/1-1:1.1':
 KERNELS=="1-1:1.1"
 SUBSYSTEMS=="usb"
 DRIVERS=="usb-storage"
 ATTRSbInterfaceClass=="08"
 ATTRSbInterfaceSubClass=="06"
 ATTRSbInterfaceProtocol=="50"
 ATTRSbNumEndpoints=="02"
 ATTRSauthorized=="1"
 ATTRSsupports_autosuspend=="1"
 ATTRSbAlternateSetting==" 0"
 ATTRSbInterfaceNumber=="01"
 ATTRSinterface=="Bulk-In, Bulk-Out, Interface"

 looking at parent device '/devices/pci0000:00/0000:00:0b.0/usb1/1-1':
 KERNELS=="1-1"
 SUBSYSTEMS=="usb"
 DRIVERS=="usb"
 ATTRSbDeviceSubClass=="00"
 ATTRSbDeviceProtocol=="00"
 ATTRSdevpath=="1"
 ATTRSidVendor=="0bda"
 ATTRSspeed=="480"
 ATTRSbNumInterfaces==" 2"
 ATTRSbConfigurationValue=="1"
 ATTRSbMaxPacketSize0=="64"
 ATTRSbusnum=="1"
 ATTRSdevnum=="3"
 ATTRSconfiguration=="CARD READER"
 ATTRSbMaxPower=="500mA"
 ATTRSauthorized=="1"
 ATTRSbmAttributes=="80"
 ATTRSbNumConfigurations=="1"
 ATTRSmaxchild=="0"
 ATTRSbcdDevice=="6123"
 ATTRSavoid_reset_quirk=="0"
 ATTRSquirks=="0x0"
 ATTRSserial=="20070818000000000"
 ATTRSversion==" 2.00"
 ATTRSurbnum=="126995"
 ATTRSltm_capable=="no"
 ATTRSmanufacturer=="Generic"
 ATTRSremovable=="unknown"
 ATTRSidProduct=="0161"
 ATTRSbDeviceClass=="00"
 ATTRSproduct=="USB2.0-CRW"

 looking at parent device '/devices/pci0000:00/0000:00:0b.0/usb1':
 KERNELS=="usb1"
 SUBSYSTEMS=="usb"
 DRIVERS=="usb"
 ATTRSbDeviceSubClass=="00"
 ATTRSbDeviceProtocol=="00"
 ATTRSdevpath=="0"
 ATTRSidVendor=="1d6b"
 ATTRSspeed=="480"
 ATTRSbNumInterfaces==" 1"
 ATTRSbConfigurationValue=="1"
 ATTRSbMaxPacketSize0=="64"
 ATTRSauthorized_default=="1"
 ATTRSbusnum=="1"
 ATTRSdevnum=="1"
 ATTRSconfiguration==""
 ATTRSbMaxPower=="0mA"
 ATTRSauthorized=="1"
 ATTRSbmAttributes=="e0"
 ATTRSbNumConfigurations=="1"
 ATTRSmaxchild=="12"
 ATTRSinterface_authorized_default=="1"
 ATTRSbcdDevice=="0404"
 ATTRSavoid_reset_quirk=="0"
 ATTRSquirks=="0x0"
 ATTRSserial=="0000:00:0b.0"
 ATTRSversion==" 2.00"
 ATTRSurbnum=="101"
 ATTRSltm_capable=="no"
 ATTRSmanufacturer=="Linux 4.4.0-116-generic ehci_hcd"
 ATTRSremovable=="unknown"
 ATTRSidProduct=="0002"
 ATTRSbDeviceClass=="09"
 ATTRSproduct=="EHCI Host Controller"

 looking at parent device '/devices/pci0000:00/0000:00:0b.0':
 KERNELS=="0000:00:0b.0"
 SUBSYSTEMS=="pci"
 DRIVERS=="ehci-pci"
 ATTRSirq=="19"
 ATTRSsubsystem_vendor=="0x0000"
 ATTRSbroken_parity_status=="0"
 ATTRSclass=="0x0c0320"
 ATTRScompanion==""
 ATTRSdriver_override=="(null)"
 ATTRSconsistent_dma_mask_bits=="32"
 ATTRSdma_mask_bits=="32"
 ATTRSlocal_cpus=="f"
 ATTRSdevice=="0x265c"
 ATTRSuframe_periodic_max=="100"
 ATTRSenable=="1"
 ATTRSmsi_bus=="1"
 ATTRSlocal_cpulist=="0-3"
 ATTRSvendor=="0x8086"
 ATTRSsubsystem_device=="0x0000"
 ATTRSnuma_node=="-1"
 ATTRSd3cold_allowed=="0"

 looking at parent device '/devices/pci0000:00':
 KERNELS=="pci0000:00"
 SUBSYSTEMS==""
 DRIVERS==""

The rule is too generic and matched all the nodes /dev/sdd, /dev/sdd1, /dev/sdd2. It matches the block device and its partitions nodes.

So udev:

1. creates a symlink /dev/sdcard → /dev/sdd


2. and quickly replaces it with /dev/sdcard → /dev/sdd1


3. then again with /dev/sdcard → /dev/sdd2

See with this rule:

ATTRremovable=="1",SUBSYSTEM=="block",DRIVERS=="sd",SYMLINK+="sdcard",GROUP="rawdisk"

Note, I replaced SUBSYSTEMS,ATTRS with SUBSYSTEM,ATTR.