Re: Of removable devices

[david parsons]

In article <[e-mail]>,
Francis GALIEGUE  <[e-mail]> wrote:
>David Balazic <[e-mail]> writes:
>
>> > 
>> > And who gets the notice if no one is there? or no one is logged in? 
>> 
>[skipped sarcasm]
>> 
>> The one that ejected the medium , obviously.
>>  echo "Put that back in , son !" > /dev/console
>> 
>> satisfied ?
>> 
>
>No. The sole role of the kernel in case of broken hardware
>(hence, floppies) is to ensure data integrity, not to tell the user
>"please insert floppy #adead007". Easing removable media manipulation
>would sure be a great plus (for users), but not to the expense of
>unneeded and unnecessary tell-user-what-to-do stuff.

    Only if it's done incorrectly.  If there's glue to put a notifier
    in, then all the kernel has to do when it attempts to write out data
    to a device that's not there anymore is tickle the notifier, then
    defer the writes 'til the next time sync rolls around.  No notifier
    == data is written to the afterlife with the traditional vomiting of
    error messages to syslog, the console, or whereever.

>And even if user space notification and report were implemented and
>functional, a user in a hurry is a user in a hurry and would be far
>away from the culprit machine

    That would be a badly implemented userland.  I couldn't imagine
    mounting anything async with a notifier, for then the machine that's
    not running update won't notice that the floppy's gone for several
    weeks.

    A sick notifier could be a simple shellscript, called by mount:

	#! /bin/sh

	DEV=$1
	MAJOR=$2
	MINOR=$3
	mknod /dev/$DEV.tickle $MAJOR $MINOR

	trap 0 1 2 3 9 15 "rm -f /dev/$DEV.tickle"

	while read tickle; do
	    dialog --msgbox --wait 5 "Please put $DEV back"
	    sync $DEV
	done < /dev/$DEV.notify
	exit 0

    with fstab being something like

	/dev/ide0/drive0	/zip	removable,notifier,user,noauto 0 0

                  ____
    david parsons \bi/ A more sophisticated tickler is left as an exercise
                   \/                                       for the reader.