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

From: Gene Heskett (gene.heskett_at_verizon.net)
Date: 01/08/04

  • Next message: Carlos Azevedo: "Kernel hang with MSI KT3-UltraARU and kernel > 2.4.19-rc3" 
    To: Linus Torvalds <torvalds@osdl.org>, Olaf Hering <olh@suse.de>
Date:	Wed, 7 Jan 2004 23:16:18 -0500

    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
AMD K6-III@500mhz 320M
Athlon1600XP@1400mhz  512M
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Copyright 2003 by Maurice Eugene Heskett, all rights reserved.
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