Sir Al
Guru
Joined: 08 Jul 2003
Posts: 326
Location: Vancouver, Canada
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 Posted: Wed Jul 30, 2003 8:35 am Post subject: Supermount is BAD (until you convince me otherwise) |
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I've been using supermount fine with no problems ever since I've been using. I had used, removed and inserted many media mounted as supermount, in mandrake and gentoo, I had never any problems. But today I had an incident with it that stopped me from using it -- ever again (unless someone can advise me on how to fix this problem).
I inserted a CD that had one video file on it. I browsed with konqueror to the location of that video file within the cd. I played the video file with the mplayer netscape-plugin off the cd, then after a few seconds aborted mplayer (using Esc). I waited a few seconds. All that was using the CD at that moment was konqueror displaying the location of the video file. I pressed the eject button on the cd.
It ejected the cd after it waited for a few short seconds. This is a sign that no write operations were being done to the CD, and basically you should be able to eject the cd anytime you wish without causing much harm (except for causing the applications to abort). Anyway, I took out the cd and injected the now empty tray. As I was about to put the CD back into its place, I heard my system's start up noise. My PC had rebooted!!! This was a complete unexpectancy, and I had lost all and all settings I had made in some file and some other stuff I was working, browsing and checking out.
This somewhat saddened me, but I wanted to find out what was causing this problem. I tried checking the log files and of course metalog had its buffering enabled, so it wasn't much help. I didn't really care what happened one hour ago, I wanted the information right before it rebooted on its own! So, I disable metalog's buffering system and force it to write in sync. I decided to recreate this error. This time I had 'tail -f /var/log/everything/current' running to show me what's going on. I took out the same cd, popped it in the same way, browsed the same way as before, watched the movie, exited mplayer and ejected the cd. The log was interesting to watch and somewhat humerous. Here is an excerpt:
| Code: | Jul 29 17:36:52 [kernel] sr0: mmc-3 profile: 0h
Jul 29 17:36:52 [kernel] cdrom: open failed.
Jul 29 17:36:52 [kernel] sr0: mmc-3 profile: 0h
Jul 29 17:36:52 [kernel] cdrom: open failed.
Jul 29 17:36:55 [kernel] cdrom: open failed.
Jul 29 17:36:55 [kernel] cdrom: open failed.
Jul 29 17:36:56 [kernel] sr0: mmc-3 profile: 0h
Jul 29 17:36:56 [kernel] cdrom: open failed.
Jul 29 17:36:56 [kernel] sr0: mmc-3 profile: 0h
Jul 29 17:36:56 [kernel] cdrom: open failed.
Jul 29 17:37:38 [kernel] Linux version 2.4.20-gentoo-r5 (root@Al) (gcc version 3.2.3 20030422 (Gentoo Linux 1.4 3.2.3-r1, propolice)) #7 Sat Jul 26 02:51:37 PDT 2003
Jul 29 17:37:38 [kernel] BIOS-provided physical RAM map: |
As you can see, this already includes the foreshadowing =) What's really funny is the 0h in the log, it seems like as if it's "You gotta use a profile!", response: "Oh.".
After ejecting: Hmm, nothing really happened... I waited for what it seemed like an eternity, yet in reality must have been mere seconds. I watched my CD-ROM drive load the tray back on its own (strange). Sweat began to accumulate on my forehead, my hands trembling to see the outcome of this test. My mind was set on this experience and the chances and results, clues it could provide. Will it be useful? I dwelled among these questions as my pc rebooted. Problem solved, supermount out and normal mount in... I considered automount, but frowned at its setup after reading the documentation. I looked at submount, and it seemed very promising, but it wasn't included in the gentoo kernel and is really still very experimental.
The ironic thing about this is that this happened just a few hours after I spent some time reading up on supermount including its feeble manual. I was quite impressed with it, actually. I liked the features and it seemed as if it was perfect for my needs. I spent some time trying to get it to work with both ext2 and dos floppies, but it doesn't look like you can have a umask option in any mount command when you want the file system to be auto-detect and still want to use ext2. I don't my fiddeling around with the floppy drive settings could have changed anything, all I did was try supermount with floppies, no probs there. However, if supermount puts my system stability into risk, there is no other choice but to eliminate it.
Here is my old fstab containing only supermount entries:
| Code: | none /mnt/cdrom supermount dev=/dev/sr0,fs=auto,ro,--,iocharset=utf8,umask=0 0 0
none /mnt/cdrom2 supermount dev=/dev/hdd,fs=auto,ro,--,iocharset=utf8,umask=0 0 0
none /mnt/floppy supermount dev=/dev/fd0,fs=auto,--,iocharset=utf8,sync,umask=0 0 0 |
Here is my new   fstab containing zero, null, ziltch words even relating to supermount (again, this only contains entries which were previously supermounted):
| Code: | /dev/sr0 /mnt/cdrom auto user,ro,iocharset=utf8,umask=0,noauto 0 0
/dev/hdd /mnt/cdrom2 auto user,ro,iocharset=utf8,umask=0,noauto 0 0
/dev/fd0 /mnt/floppy auto user,dev,noauto,suid,exec,iocharset=utf8 0 0 |
Now all reference of supermount is off my system, and my kernel does not have it in its config anymore, what a relief
Don't get me wrong. I think supermount is an awesome way to 'mount' when it works. But I don't think it's for me. When a system reboots by the soul use of supermount, I consider supermount not to be a viable option for me. I have tried the same procedure using the normal mount, and it worked without a glitch. On top of that it seems to mount my drives quicker and browse directories quicker. The only annoyance is the requirement to mount/unmount, even more annoying if you have multiple users (not really an issue for me). I must say that I haven't been using supermount for extremely long in gentoo, but in mandrake I've never had this problem and I've used it for over a year there. It possibly could be some kind of gentoo problem... but then again, not many other gentoo people experience this, right? Or do most of them just use the normal mount command like me now?
Sadly, I must say goodbye to the supermount world. Two reboots is enough for me to quit. Even on my Windows XP machine I have not seen it reboot of error so often.
Are there any ideas on why/how such a thing could occur? I've come across such posts from mandrake users, but I never bothered to read them because supermount did the job for me and worked without any errors that I could see. That is, until it attacked and devoured me. Anyone could be next, so watch out and use anti-supermount protection! 
No seriously, watch out for supermount, it could at any time cause dataloss, even when you're using only Read-Only media with it!
P.S. I don't think it's related, but I've stopped seeing those "Mutex error" messages randomly appearing in the console ever since supermount has been eliminated.
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