Debian bug report logs - #379
Repeatable mount(1) problem with removable disks
Package: mount; Reported by: Bill Mitchell <mitchell@mdd.comm.mot.com>; 269 days old.
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From pixar.com!bruce Fri Aug 4 21:30:44 1995
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Date: Fri, 4 Aug 95 21:30 PDT
From: bruce@pixar.com (Bruce Perens)
To: mitchell@mdd.comm.mot.com, debian-bugs@pixar.com
Subject: Re: Bug#379: Repeatable mount(1) problem with removable disks
Bill,
Can you report on whether or not this bug still exists in kernel-1.2.12 ?
I consider this a kernel problem.
Thanks
Bruce Perens
--
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Acknowledgement sent to bruce@pixar.com (Bruce Perens):
Extra info received and forwarded.
Full text available.
Information forwarded to debian-devel@pixar.com:
Bug#379; Package mount.
Full text available.
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From mdd.comm.mot.com!mitchell Sun Feb 5 10:35:28 1995
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Date: Sun, 5 Feb 1995 10:35:12 -0800 (PST)
From: Bill Mitchell <mitchell@mdd.comm.mot.com>
X-Sender: mitchell@bb29c
To: Ian Jackson <iwj10@cus.cam.ac.uk>
Cc: debian-bugs@pixar.com
Subject: Re: Bug#379: Repeatable mount(1) problem with removable disks
In-Reply-To: <m0rb6Fh-0002g8Z.ijackson@nyx.cs.du.edu>
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On Sun, 5 Feb 1995, Ian Jackson wrote:
> [...]
> There is an ioctl that causes the kernel to re-read the partition
> table; this is used by fdisk. [... but not used by mount ... (wtm)]
>
> [...] what
> if you insert a cartridge that has a /dev/sdc4 but whose sdc4 is the
> wrong size ?
Ouch! This sounds like I could have one cartridge with a single
150MB partition on /dev/sdc1 mounted, unmount it and mount /dev/scd1
from another cartridge which has two 75MB partitions, and trash
the second partition. No... perhaps not. Surely mounting the
new partition would involve reading in the superblock, or whatever
disk usage and sizing information the mounted filesystem contains.
On the other hand, what about the case where I had that 75MB
/dev/sdc1 partition mounted, unmounted it and mounted a 150MB
/dev/sdc1 partition from another cartridge? If the partition
table is not reread, mount will read in disk usage information
showing that the filesystem it's mounted is bigger than the
un-reread partition table shows the partition where it resides
to be. Messy.
> The right solution is surely to make sure that the kernel spots the
> cartridge change and invalidates the partition table information
> itself.
Yes, but is it "right" for mount not to be paranoid enough to re-read
the partition table before attempting a mount? If nothing else, having
mount reread the partition table before attempting a mount would provide
protection to folks using a later vintage mount program with an earlier
vintage kernel.
> Is there anything about this in the SCSI HOWTO ? If not you should
> probably report it as a bug to the SCSI mailing list.
I happen have a removable-cartridge disk which has a SCSI interface,
but it seems to me these same concerns would apply to a removeable
cartridge disk with an IDE <or whatever> interface as well.
Message sent:
From: iwj@cam-orl.co.uk (Ian Jackson)
To: Bill Mitchell <mitchell@mdd.comm.mot.com>
Subject: Bug#379: Info received (was Bug#379: Repeatable mount(1) problem with removable disks)
In-Reply-To: <Pine.SUN.3.90.950205101406.4161D-100000@bb29c>
References: <Pine.SUN.3.90.950205101406.4161D-100000@bb29c>
Thank you for the additional information you have supplied regarding
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accompany the original report.
If you wish to continue submit further information on your problem,
please do the same thing again: send it to debian-bugs@pixar.com, ensuring
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Please do not to reply to the address at the top of this message,
unless you wish to report a problem with the bug-tracking system.
Ian Jackson
(maintainer, debian-bugs)
Message sent to debian-devel@pixar.com:
Subject: Bug#379: Repeatable mount(1) problem with removable disks
Reply-To: Bill Mitchell <mitchell@mdd.comm.mot.com>, debian-bugs-done@pixar.com
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Date: Sun, 5 Feb 1995 10:35:12 -0800 (PST)
From: Bill Mitchell <mitchell@mdd.comm.mot.com>
X-Sender: mitchell@bb29c
To: Ian Jackson <iwj10@cus.cam.ac.uk>
Cc: debian-bugs@pixar.com
In-Reply-To: <m0rb6Fh-0002g8Z.ijackson@nyx.cs.du.edu>
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On Sun, 5 Feb 1995, Ian Jackson wrote:
> [...]
> There is an ioctl that causes the kernel to re-read the partition
> table; this is used by fdisk. [... but not used by mount ... (wtm)]
>
> [...] what
> if you insert a cartridge that has a /dev/sdc4 but whose sdc4 is the
> wrong size ?
Ouch! This sounds like I could have one cartridge with a single
150MB partition on /dev/sdc1 mounted, unmount it and mount /dev/scd1
from another cartridge which has two 75MB partitions, and trash
the second partition. No... perhaps not. Surely mounting the
new partition would involve reading in the superblock, or whatever
disk usage and sizing information the mounted filesystem contains.
On the other hand, what about the case where I had that 75MB
/dev/sdc1 partition mounted, unmounted it and mounted a 150MB
/dev/sdc1 partition from another cartridge? If the partition
table is not reread, mount will read in disk usage information
showing that the filesystem it's mounted is bigger than the
un-reread partition table shows the partition where it resides
to be. Messy.
> The right solution is surely to make sure that the kernel spots the
> cartridge change and invalidates the partition table information
> itself.
Yes, but is it "right" for mount not to be paranoid enough to re-read
the partition table before attempting a mount? If nothing else, having
mount reread the partition table before attempting a mount would provide
protection to folks using a later vintage mount program with an earlier
vintage kernel.
> Is there anything about this in the SCSI HOWTO ? If not you should
> probably report it as a bug to the SCSI mailing list.
I happen have a removable-cartridge disk which has a SCSI interface,
but it seems to me these same concerns would apply to a removeable
cartridge disk with an IDE <or whatever> interface as well.
Message received at debian-bugs:
From cus.cam.ac.uk!iwj10 Sun Feb 5 08:52:42 1995
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Date: Sun, 5 Feb 95 12:39 GMT
From: iwj10@cus.cam.ac.uk (Ian Jackson)
To: debian-bugs@pixar.com
Subject: Re: Bug#379: Repeatable mount(1) problem with removable disks
Bill Mitchell writes ("Bug#379: Repeatable mount(1) problem with removable disks"):
> [...]
> I report this as a mount(1) problem instead of a kernel problem
> because I've noticed that I can clear the problem by running
> fdisk /dev/sdc
> and then exiting fdisk. If I do this in between the unmount of a
> cartridge with one partition present and the mount of a cartridge
> with another partition present, the mount succeeds. Apparently
> fdisk(1) causes the partition information to be re-read from the
> disk.
There is an ioctl that causes the kernel to re-read the partition
table; this is used by fdisk.
> I'm suggesting that mount(1) should also re-read the partition
> information from the disk. It should either do this all the time,
> or it should do it after a mount failure, then retrythe mount request
> before considering the failure to be a hard one and reporting it.
No, I don't think it should. Certainly the latter won't work - what
if you insert a cartridge that has a /dev/sdc4 but whose sdc4 is the
wrong size ?
The right solution is surely to make sure that the kernel spots the
cartridge change and invalidates the partition table information
itself.
Is there anything about this in the SCSI HOWTO ? If not you should
probably report it as a bug to the SCSI mailing list.
Regards,
Ian.
Message sent:
From: iwj@cam-orl.co.uk (Ian Jackson)
To: iwj10@cus.cam.ac.uk (Ian Jackson)
Subject: Bug#379: Info received (was Bug#379: Repeatable mount(1) problem with removable disks)
In-Reply-To: <m0rb6Fh-0002g8Z.ijackson@nyx.cs.du.edu>
References: <m0rb6Fh-0002g8Z.ijackson@nyx.cs.du.edu>
Thank you for the additional information you have supplied regarding
your problem report. It has been forwarded to the developers to
accompany the original report.
If you wish to continue submit further information on your problem,
please do the same thing again: send it to debian-bugs@pixar.com, ensuring
that the Subject line starts with "Bug#379" or "Re: Bug#379" so that
we can identify it as relating to the same problem.
Please do not to reply to the address at the top of this message,
unless you wish to report a problem with the bug-tracking system.
Ian Jackson
(maintainer, debian-bugs)
Message sent to debian-devel@pixar.com:
Subject: Bug#379: Repeatable mount(1) problem with removable disks
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Date: Sun, 5 Feb 95 12:39 GMT
From: iwj10@cus.cam.ac.uk (Ian Jackson)
To: debian-bugs@pixar.com
Bill Mitchell writes ("Bug#379: Repeatable mount(1) problem with removable disks"):
> [...]
> I report this as a mount(1) problem instead of a kernel problem
> because I've noticed that I can clear the problem by running
> fdisk /dev/sdc
> and then exiting fdisk. If I do this in between the unmount of a
> cartridge with one partition present and the mount of a cartridge
> with another partition present, the mount succeeds. Apparently
> fdisk(1) causes the partition information to be re-read from the
> disk.
There is an ioctl that causes the kernel to re-read the partition
table; this is used by fdisk.
> I'm suggesting that mount(1) should also re-read the partition
> information from the disk. It should either do this all the time,
> or it should do it after a mount failure, then retrythe mount request
> before considering the failure to be a hard one and reporting it.
No, I don't think it should. Certainly the latter won't work - what
if you insert a cartridge that has a /dev/sdc4 but whose sdc4 is the
wrong size ?
The right solution is surely to make sure that the kernel spots the
cartridge change and invalidates the partition table information
itself.
Is there anything about this in the SCSI HOWTO ? If not you should
probably report it as a bug to the SCSI mailing list.
Regards,
Ian.
Message received at debian-bugs:
From mdd.comm.mot.com!mitchell Sat Feb 4 10:45:20 1995
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Date: Sat, 4 Feb 1995 10:45:13 -0800 (PST)
From: Bill Mitchell <mitchell@mdd.comm.mot.com>
X-Sender: mitchell@bb29c
To: debian-bugs@pixar.com
Subject: Repeatable mount(1) problem with removable disks
In-Reply-To: <Pine.SUN.3.90.950204100804.3156A-100000@bb29c>
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PACKAGE: mount
VARSION: 1.10
PACKAGE_REVISION: 4 (and later?)
One of the devices on my system is a removeable cartridge disk drive.
I have this on /dev/sdc.
The disk cartridges come preformatted for MSDOS, with partitions
1 thru 3 not present and with an MSDOS filesystem in partition 4.
I use them the way they come out of the box for MSDOS use.
I also use this disk for ext2 filesystems. I usually repartition
a disk cartridge so that partition 1 is present instead of partition 4,
and put an ext2 filesystem in partition 1.
So, to mount a disk cartridge, I usually say one of the following:
mount -t msdos /dev/sdc4 /mnt
mount -t ext2 /dev/sdc1 /mnt
This works fine for the initial mount of this disk, and works just
fine if I unmount and remount disks of the same type. However, if
I unmount an MSDOS disk and try to mount an ext2 disk, mount(1)
fails with the message:
mount: /dev/sdc1 is not a valid block device
and I get a similar failure message for /dev/sdc4 when trying to
mount an MSDOS disk after I've unmounted an ext2 disk.
Apparently the partition table info is kept cached somewhere in the
kernel, and mount requests use this cached info instead of re-reading
the partition table from the disk.
I report this as a mount(1) problem instead of a kernel problem
because I've noticed that I can clear the problem by running
fdisk /dev/sdc
and then exiting fdisk. If I do this in between the unmount of a
cartridge with one partition present and the mount of a cartridge
with another partition present, the mount succeeds. Apparently
fdisk(1) causes the partition information to be re-read from the
disk.
I'm suggesting that mount(1) should also re-read the partition
information from the disk. It should either do this all the time,
or it should do it after a mount failure, then retrythe mount request
before considering the failure to be a hard one and reporting it.
mitchell@mdd.comm.mot.com (Bill Mitchell)
Message sent:
From: iwj@cam-orl.co.uk (Ian Jackson)
To: Bill Mitchell <mitchell@mdd.comm.mot.com>
Subject: Bug#379: Acknowledgement (was: Repeatable mount(1) problem with removable disks)
In-Reply-To: <Pine.SUN.3.90.950204104141.3198E-100000@bb29c>
References: <Pine.SUN.3.90.950204104141.3198E-100000@bb29c>
Thank you for the problem report you have sent regarding Debian GNU/Linux.
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Please do not to reply to the address at the top of this message,
unless you wish to report a problem with the bug-tracking system.
Ian Jackson
(maintainer, debian-bugs)
Message sent to debian-devel@pixar.com:
Subject: Bug#379: Repeatable mount(1) problem with removable disks
Reply-To: Bill Mitchell <mitchell@mdd.comm.mot.com>, debian-bugs-done@pixar.com
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Date: Sat, 4 Feb 1995 10:45:13 -0800 (PST)
From: Bill Mitchell <mitchell@mdd.comm.mot.com>
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To: debian-bugs@pixar.com
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Mime-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
PACKAGE: mount
VARSION: 1.10
PACKAGE_REVISION: 4 (and later?)
One of the devices on my system is a removeable cartridge disk drive.
I have this on /dev/sdc.
The disk cartridges come preformatted for MSDOS, with partitions
1 thru 3 not present and with an MSDOS filesystem in partition 4.
I use them the way they come out of the box for MSDOS use.
I also use this disk for ext2 filesystems. I usually repartition
a disk cartridge so that partition 1 is present instead of partition 4,
and put an ext2 filesystem in partition 1.
So, to mount a disk cartridge, I usually say one of the following:
mount -t msdos /dev/sdc4 /mnt
mount -t ext2 /dev/sdc1 /mnt
This works fine for the initial mount of this disk, and works just
fine if I unmount and remount disks of the same type. However, if
I unmount an MSDOS disk and try to mount an ext2 disk, mount(1)
fails with the message:
mount: /dev/sdc1 is not a valid block device
and I get a similar failure message for /dev/sdc4 when trying to
mount an MSDOS disk after I've unmounted an ext2 disk.
Apparently the partition table info is kept cached somewhere in the
kernel, and mount requests use this cached info instead of re-reading
the partition table from the disk.
I report this as a mount(1) problem instead of a kernel problem
because I've noticed that I can clear the problem by running
fdisk /dev/sdc
and then exiting fdisk. If I do this in between the unmount of a
cartridge with one partition present and the mount of a cartridge
with another partition present, the mount succeeds. Apparently
fdisk(1) causes the partition information to be re-read from the
disk.
I'm suggesting that mount(1) should also re-read the partition
information from the disk. It should either do this all the time,
or it should do it after a mount failure, then retrythe mount request
before considering the failure to be a hard one and reporting it.
mitchell@mdd.comm.mot.com (Bill Mitchell)
Ian Jackson /
iwj10@thor.cam.ac.uk,
with the debian-bugs tracking mechanism