Re: Wrong symlink handling on rule changes

[Matthias Schwarzott <zzam@gentoo.org>]

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On Donnerstag, 20. September 2007, Kay Sievers wrote:
> On 9/20/07, Matthias Schwarzott <zzam@gentoo.org> wrote:
> > Playing around with rules I stepped over a strange thing.
> >
> > I played with device-mapper rules, but the bug is about general symlink
> > handling.
> >
> > 1. My rules did set this:
> > NAME="dm-0", SYMLINK="mapper/main-slash"
> > That results in /dev/dm-0 being a device-node and /dev/mapper/main-slash
> > is a symlink to it.
> >
> > 2. Swapping NAME and SYMLINK
> > NAME="mapper/main-slash", SYMLINK="dm-0"
> > and running udevtrigger changes dm-0 to be a symlink to correct target.
> > BUT: It changes mapper/main-slash to be a symlink to itself.
> >
> > Calling udevtrigger a second time will correct symlink.
>
> Might be fixed by this:
> http://git.kernel.org/?p=linux/hotplug/udev.git;a=commitdiff;h=25c208d659cf
>0f8bc887a1f7c62e9d2e0c546aec
>
> I general, it's a bad idea to mess around with device nodes created by
> other tools. Libdevmapper needs proper udev/kernel event integration
> to allow this without doing unpredictable things.
>
I know, but this was just an example. See my other example using sda and a 
symlink on it.

Even updating to latest git (that does contain patch above) does not help in 
this case.

Part of udevtest output (instead of udevtrigger call after rule change):

# grep try1 /tmp/udevtest-sda.txt
udev_rules_get_name: rule applied, 'sda' becomes 'try1'
udev_node_add: creating device node '/dev/try1', major=8, minor=0, mode=0640, 
uid=0, gid=6
update_link: 'sda' with target 'try1' has the highest priority 0, create it
update_link: 'disk/by-id/scsi-SATA_SAMSUNG_XXX' with target 'try1' has the 
highest priority 0, create it
update_link: 'disk/by-id/ata-SAMSUNG_XXX' with target 'try1' has the highest 
priority 0, create it
update_link: 'disk/by-path/pci-0000:00:0f.0-scsi-0:0:0:0' with target 'try1' 
has the highest priority 0, create it
udev_node_update_symlinks: update old symlink 'try1' no longer belonging 
to '/block/sda'
udev_db_get_devices_by_name: found index directory '/dev/.udev/names/try1'
update_link: found 1 devices with name 'try1'
update_link: found '/block/sda' for 'try1'
update_link: 'try1' with target 'try1' has the highest priority 0, create it
update_link: 'sda' with target 'try1' has the highest priority 0, create it



See the line that tells that try1 symlink has highest priority so create it.

Matthias

-- 
Matthias Schwarzott (zzam)

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This program is for debugging only, it does not run any program,
specified by a RUN key. It may show incorrect results, because
some values may be different, or not available at a simulation run.

main: looking at device '/block/sda' from subsystem 'block'
udev_rules_get_name: add symlink 'sda'
udev_rules_get_name: rule applied, 'sda' becomes 'try1'
match_rule: set ENV 'DEVTYPE=disk'
run_program: 'usb_id --export /block/sda'
run_program: '/lib/udev/usb_id' returned with status 1
run_program: 'scsi_id --export --whitelisted --fallback-to-sysfs -s /block/sda -d /dev/.tmp-8-0'
run_program: '/lib/udev/scsi_id' (stdout) 'ID_VENDOR=ATA'
run_program: '/lib/udev/scsi_id' (stdout) 'ID_MODEL=SAMSUNG_XXX'
run_program: '/lib/udev/scsi_id' (stdout) 'ID_REVISION=ZZ10'
run_program: '/lib/udev/scsi_id' (stdout) 'ID_SERIAL=XXX'
run_program: '/lib/udev/scsi_id' (stdout) 'ID_SERIAL_SHORT=XXX'
run_program: '/lib/udev/scsi_id' (stdout) 'ID_TYPE=disk'
run_program: '/lib/udev/scsi_id' (stdout) 'ID_BUS=scsi'
run_program: '/lib/udev/scsi_id' returned with status 0
udev_rules_get_name: add symlink 'disk/by-id/scsi-SATA_SAMSUNG_XXX'
run_program: 'ata_id /dev/.tmp-8-0'
run_program: '/lib/udev/ata_id' returned with status 0
match_rule: set ENV 'ID_ATA_COMPAT=SAMSUNG_XXX'
udev_rules_get_name: add symlink 'disk/by-id/ata-SAMSUNG_XXX'
run_program: 'path_id /block/sda'
run_program: '/lib/udev/path_id' (stdout) 'ID_PATH=pci-0000:00:0f.0-scsi-0:0:0:0'
run_program: '/lib/udev/path_id' returned with status 0
udev_rules_get_name: add symlink 'disk/by-path/pci-0000:00:0f.0-scsi-0:0:0:0'
run_program: 'edd_id --export /dev/.tmp-8-0'
run_program: '/lib/udev/edd_id' (stderr) 'no kernel EDD support'
run_program: '/lib/udev/edd_id' returned with status 2
udev_device_event: device '/block/sda' already in database, cleanup
udev_node_add: creating device node '/dev/try1', major=8, minor=0, mode=0640, uid=0, gid=6
udev_node_update_symlinks: update symlink 'sda' of '/block/sda'
udev_db_get_devices_by_name: found index directory '/dev/.udev/names/sda'
update_link: found 1 devices with name 'sda'
update_link: found '/block/sda' for 'sda'
update_link: compare (our own) priority of '/block/sda' 0 >= 0
update_link: 'sda' with target 'try1' has the highest priority 0, create it
udev_node_update_symlinks: update symlink 'disk/by-id/scsi-SATA_SAMSUNG_XXX' of '/block/sda'
udev_db_get_devices_by_name: found index directory '/dev/.udev/names/disk\x2fby-id\x2fscsi-SATA_SAMSUNG_XXX'
update_link: found 1 devices with name 'disk/by-id/scsi-SATA_SAMSUNG_XXX'
update_link: found '/block/sda' for 'disk/by-id/scsi-SATA_SAMSUNG_XXX'
update_link: compare (our own) priority of '/block/sda' 0 >= 0
update_link: 'disk/by-id/scsi-SATA_SAMSUNG_XXX' with target 'try1' has the highest priority 0, create it
udev_node_update_symlinks: update symlink 'disk/by-id/ata-SAMSUNG_XXX' of '/block/sda'
udev_db_get_devices_by_name: found index directory '/dev/.udev/names/disk\x2fby-id\x2fata-SAMSUNG_XXX'
update_link: found 1 devices with name 'disk/by-id/ata-SAMSUNG_XXX'
update_link: found '/block/sda' for 'disk/by-id/ata-SAMSUNG_XXX'
update_link: compare (our own) priority of '/block/sda' 0 >= 0
update_link: 'disk/by-id/ata-SAMSUNG_XXX' with target 'try1' has the highest priority 0, create it
udev_node_update_symlinks: update symlink 'disk/by-path/pci-0000:00:0f.0-scsi-0:0:0:0' of '/block/sda'
udev_db_get_devices_by_name: found index directory '/dev/.udev/names/disk\x2fby-path\x2fpci-0000:00:0f.0-scsi-0:0:0:0'
update_link: found 1 devices with name 'disk/by-path/pci-0000:00:0f.0-scsi-0:0:0:0'
update_link: found '/block/sda' for 'disk/by-path/pci-0000:00:0f.0-scsi-0:0:0:0'
update_link: compare (our own) priority of '/block/sda' 0 >= 0
update_link: 'disk/by-path/pci-0000:00:0f.0-scsi-0:0:0:0' with target 'try1' has the highest priority 0, create it
udev_node_update_symlinks: update old symlink 'try1' no longer belonging to '/block/sda'
udev_db_get_devices_by_name: found index directory '/dev/.udev/names/try1'
update_link: found 1 devices with name 'try1'
update_link: found '/block/sda' for 'try1'
update_link: compare (our own) priority of '/block/sda' 0 >= 0
update_link: 'try1' with target 'try1' has the highest priority 0, create it
udev_db_get_devices_by_name: found index directory '/dev/.udev/names/sda'
update_link: found 1 devices with name 'sda'
update_link: found '/block/sda' for 'sda'
update_link: compare (our own) priority of '/block/sda' 0 >= 0
update_link: 'sda' with target 'try1' has the highest priority 0, create it
main: run: 'socket:/org/freedesktop/hal/udev_event'
main: run: 'socket:/org/kernel/udev/monitor'

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