Re: removable media revalidation - udev vs. devfs or static /dev

Gene Heskett
2004-01-08T04:16:25Z

On Wednesday 07 January 2004 21:03, Linus Torvalds wrote:
>On Wed, 7 Jan 2004, Olaf Hering wrote:
>> > Then, user space can just access "/dev/sda1" or whatever, and
>> > the act of accessing it will force the re-scan.
>>
>> How would that work? I mean, what will a tool that cares about a
>> block event do? It will run a fdisk/parted -l /udev/sda to figure
>> out what partitions are there (just to skip an extended partition
>> sda5, as example) and finds no media. That tool will never run
>> again on sda, unless a new block add event comes in. So some sort
>> of polling is required for that class of devices.
>
>What is your problem?
>
>I'll use a very common and simple case that I do myself: use any USB
> media reader to read a camera card. It will be a FAT filesystem on
> the first partition, so your fstab might look like this:
>
> /dev/sda1 /mnt/smartmedia vfat
> noauto,user,ro 0 0
>
>and then you just do "mount /mnt/smartmedia", and you're done.
>
>This works. I do it all the time. You just stick in your card, and
> mount it, and off it foes. No "fdisk" or "parted" _anywhere_.

I do too, except the card is still in my camera when I do it. But, I
do have to ask, why the ro? I regularly do housekeeping in the
camera once I've downloaded the images I want. The only problem I've
had is related to deleting the first images all in a row. Apparently
fat thinks an empty sector is the end of the directory. So one must
delete on LIFO basis.

> Linus
>-
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--
Cheers, Gene
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Copyright 2003 by Maurice Eugene Heskett, all rights reserved.