Udev 100: Inconsistency in 60-persistent-storage.rules?

Udev 100: Inconsistency in 60-persistent-storage.rules?

[Alexander E. Patrakov]

Hello,

the 60-persistent-storage.rules file contains the following rules:

# never access non-cdrom removable ide devices, the drivers are causing 
event loops on open()
KERNEL="hd*[!0-9]", ATTRS{removable}="1", 
DRIVERS="ide-cs|ide-floppy", GOTO="persistent_storage_end"
KERNEL="hd*[0-9]", ATTRS{removable}="1", GOTO="persistent_storage_end"

# <snip>

# by-label/by-uuid (filesystem properties)
KERNEL="*[!0-9]", ATTR{removable}="1", GOTO="persistent_storage_end"

# <snip>

LABEL="persistent_storage_end"

What's the reason for the ATTRS vs ATTR difference? Where exactly does 
the "removable" attribute live in sysfs?

-- 
Alexander E. Patrakov

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Re: Udev 100: Inconsistency in 60-persistent-storage.rules?

[Kay Sievers]

On Fri, 2006-09-22 at 16:56 +0600, Alexander E. Patrakov wrote:
> Hello,
> 
> the 60-persistent-storage.rules file contains the following rules:
> 
> # never access non-cdrom removable ide devices, the drivers are causing 
> event loops on open()
> KERNEL="hd*[!0-9]", ATTRS{removable}="1", 
> DRIVERS="ide-cs|ide-floppy", GOTO="persistent_storage_end"
> KERNEL="hd*[0-9]", ATTRS{removable}="1", GOTO="persistent_storage_end"
> 
> # <snip>
> 
> # by-label/by-uuid (filesystem properties)
> KERNEL="*[!0-9]", ATTR{removable}="1", GOTO="persistent_storage_end"
> 
> # <snip>
> 
> LABEL="persistent_storage_end"
> 
> What's the reason for the ATTRS vs ATTR difference? Where exactly does 
> the "removable" attribute live in sysfs?

The "removable" attribute is a disk, not a partition attribute.

ATTR matches only on the device we receive the event for, ATTRS searches
up the chain of parents for a match. ATTRS, like all other *S keys is
usually more expensive, cause we may need to walk up the parent devices
to see that nothing matches.

KERNEL="*[!0-9]", ATTR{removable}="1" matches only the disk device
here, where the attribute is expected.

KERNEL="hd*[0-9]", ATTRS{removable}="1" will find the "removable"
attribute of the disk, which is the parent of the partition we match on
with KERNEL.

KERNEL="hd*[!0-9]", ATTRS{removable}="1" could be ATTR I think, cause
it will not run for a partition anyway cause of the KERNEL match.

Kay


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