[linux-lvm] e2fsadm and fstab

[linux-lvm] e2fsadm and fstab

[Jan Niehusmann]

Is the following behaviour wanted?

If a filesystem is listed in /etc/fstab, but currently not mounted, e2fsadm
checks for the availability of ext2online, and if it doesn't find it, it 
aborts with an error message. The check is in e2fsadm.c, lines 275ff.

IMHO it doesn't matter if a fs is mentioned in fstab. If it's not mounted,
we can resize it without ext2online.

Jan

Re: [linux-lvm] e2fsadm and fstab

[Andreas Dilger]

Jan writes:
> Is the following behaviour wanted?
> 
> If a filesystem is listed in /etc/fstab, but currently not mounted, e2fsadm
> checks for the availability of ext2online, and if it doesn't find it, it 
> aborts with an error message. The check is in e2fsadm.c, lines 275ff.

This sounds like a bug I added then fixed in my local version of e2fsadm.
It is not in the original e2fsadm.  I will post a patch and upload a new
SRPM.

Basically, I check /etc/fstab to do mountpoint -> device renaming for
unmounted filesystems, and /proc/mounts and /etc/mtab for mounted
filesystems.  It's no great loss if you simply remove /etc/fstab from
the list in e2fsadm of places to check for devices/filesystems for now.
It just means you need to give the LV name always instead of optionally
giving the mountpoint.

Cheers, Andreas
-- 
Andreas Dilger  \ "If a man ate a pound of pasta and a pound of antipasto,
                 \  would they cancel out, leaving him still hungry?"
http://www-mddsp.enel.ucalgary.ca/People/adilger/               -- Dogbert

Re: [linux-lvm] e2fsadm and fstab

[Jan Niehusmann]

On Fri, Sep 22, 2000 at 05:51:37PM -0600, Andreas Dilger wrote:
> This sounds like a bug I added then fixed in my local version of e2fsadm.
> It is not in the original e2fsadm.  I will post a patch and upload a new
> SRPM.

You're right, I'm using the patches from your SRPM.

> Basically, I check /etc/fstab to do mountpoint -> device renaming for
> unmounted filesystems, and /proc/mounts and /etc/mtab for mounted
> filesystems.

BTW, 2.4 allows more than one filesystem mounted on the same mountpoint. Is
this case handled correctly?

Jan

Re: [linux-lvm] e2fsadm and fstab

[Andreas Dilger]

Jan writes:
> > Basically, I check /etc/fstab to do mountpoint -> device renaming for
> > unmounted filesystems, and /proc/mounts and /etc/mtab for mounted
> > filesystems.
> 
> BTW, 2.4 allows more than one filesystem mounted on the same mountpoint. Is
> this case handled correctly?

Yes, it shouldn't be a problem, because there is only 1 device, so you can
have multiple mountpoint->device mappings, but it is the device (LV) that
has the LVM resizing done on it, and I assume there us still only 1
superblock between all of the mountpoints, so the fs resizing should be OK.

Cheers, Andreas
-- 
Andreas Dilger  \ "If a man ate a pound of pasta and a pound of antipasto,
                 \  would they cancel out, leaving him still hungry?"
http://www-mddsp.enel.ucalgary.ca/People/adilger/               -- Dogbert

Re: [linux-lvm] e2fsadm and fstab

[Christoph Hellwig]

On Sat, Sep 23, 2000 at 02:16:28AM +0200, Jan Niehusmann wrote:
> BTW, 2.4 allows more than one filesystem mounted on the same mountpoint. Is
> this case handled correctly?

It doesn't really support multiple filesystems on one mountpoint. Yes,
you can mount something multoiple times on the same point, but you will
only be able to use the last mounted one. Al Viro is still working on
union mounts.
To prevent the user from doing baad things when resizing I will add support
for detecting multiple filesystem on the same mountpoint to my lvmadm tool.

	Christoph

P.S. to Andreas: those filesystems do not share the superblock.
-- 
Always remember that you are unique.  Just like everyone else.

Re: [linux-lvm] e2fsadm and fstab

[Jan Niehusmann]

On Sat, Sep 23, 2000 at 08:31:20AM +0200, Christoph Hellwig wrote:
> It doesn't really support multiple filesystems on one mountpoint. Yes,
> you can mount something multoiple times on the same point, but you will
> only be able to use the last mounted one. Al Viro is still working on
> union mounts.

Yes I know. 
	mount /dev/a /mnt/
	mount /dev/b /mnt/

now ls /mnt/ shows the contents of device b.

/proc/mounts shows both mounts. If I use e2fsadm on /mnt/, which one
of the filesystems should be resized? 

Probably it should say someting like '/mnt/ is ambiguous' and do 
nothing. Currently, it picks the first one, which is actually invisible
in the filesystem. This is not the expected behaviour, I think.

Jan

Re: [linux-lvm] e2fsadm and fstab

[Andreas Dilger]

Jan,
> On Fri, Sep 22, 2000 at 05:51:37PM -0600, Andreas Dilger wrote:
> > This sounds like a bug I added then fixed in my local version of e2fsadm.
> > It is not in the original e2fsadm.  I will post a patch and upload a new
> > SRPM.

I had a look at this, and the correct fix is rather easy.  Where we are
checking all of the mount files, you need to move 

          if (strcmp(*mntfile, MNTTAB)) {

up abount 12 lines, so that it looks like this:

          if (strcmp(*mntfile, MNTTAB)) {
	     if ( lvm_find_command (cmd_online) == NULL) {
	        lvm_path_error ( cmd_online, "online resize");

This way, it will not assume a filesystem is mounted, if it is only
found in MNTTAB (/etc/fstab), but we can still do mountpoint -> device
mapping.  As you pointed out, it is possible with 2.4 to have multiple
device -> mountpoint mappings, but I can't see any sane reason to do
so yet, so it won't be fixed until we know how they will be used.

Cheers, Andreas
-- 
Andreas Dilger  \ "If a man ate a pound of pasta and a pound of antipasto,
                 \  would they cancel out, leaving him still hungry?"
http://www-mddsp.enel.ucalgary.ca/People/adilger/               -- Dogbert