why isn't quota dependant on ext2?

why isn't quota dependant on ext2?

[Gerhard Mack]

Anyone know why the quota menu option isn't dependant on ext2 since that's
all it works with?

	Gerhard


--
Gerhard Mack

gmack@innerfire.net

<>< As a computer I find your faith in technology amusing.

Re: why isn't quota dependant on ext2?

[Andrew Morton]

Gerhard Mack <gmack@innerfire.net> wrote:
>
> Anyone know why the quota menu option isn't dependant on ext2 since that's
> all it works with?
> 

ext3, ufs and udf also use the core quota code.

Re: why isn't quota dependant on ext2?

[Gerhard Mack]

On Tue, 21 Jan 2003, Andrew Morton wrote:

> Gerhard Mack <gmack@innerfire.net> wrote:
> >
> > Anyone know why the quota menu option isn't dependant on ext2 since that's
> > all it works with?
> >
>
> ext3, ufs and udf also use the core quota code.

The documentation says it only works with ext2 where would I find working
utilities to get it working on ext3 ?

	Gerhard


--
Gerhard Mack

gmack@innerfire.net

<>< As a computer I find your faith in technology amusing.

Re: why isn't quota dependant on ext2?

[Andrew Morton]

Gerhard Mack <gmack@innerfire.net> wrote:
>
> On Tue, 21 Jan 2003, Andrew Morton wrote:
> 
> > Gerhard Mack <gmack@innerfire.net> wrote:
> > >
> > > Anyone know why the quota menu option isn't dependant on ext2 since that's
> > > all it works with?
> > >
> >
> > ext3, ufs and udf also use the core quota code.
> 
> The documentation says it only works with ext2 where would I find working
> utilities to get it working on ext3 ?
> 

ext3 uses the same tools as ext2 - checkquota, quotaon, etc.

http://quota-tools.sourceforge.net/ (site seems to be broken)

Re: why isn't quota dependant on ext2?

[Pete Zaitcev]

>> > ext3, ufs and udf also use the core quota code.
>> 
>> The documentation says it only works with ext2 where would I find working
>> utilities to get it working on ext3 ?
> 
> ext3 uses the same tools as ext2 - checkquota, quotaon, etc.
> 
> http://quota-tools.sourceforge.net/ (site seems to be broken)

The bad news is that quota on ext3 is virtually guaranteed
to deadlock, so you can do it, but you do not want to do it.
The original memo describes a deadlock in RH 2.4.18-5, which
I assure you, was NOT fixed in Marcelo 2.4.20. A good anti-deadlock
work was done, granted, but this particular one wasn't fixed.

-- Pete

---------------------------------------------------------
Date: Mon, 21 Oct 2002 20:20:19 -0400
From: Pete Zaitcev <zaitcev@redhat.com>
Subject: Deadlock in jbd

A customer [@ Chicagolinux] had his box hanging
with 2.4.18-5, as described in Issue 4561, Bug 71379.
SysRq-T trace looks like this:

kjournald     D DD99A000     0   197      1           956   196 (L-TLB)
Call Trace: [<c0118ecb>] sleep_on [kernel] 0x4b
[<e084076e>] journal_commit_transaction [jbd] 0x15e
[<c01f0f6d>] ip_rcv [kernel] 0x39d
[<e0843806>] kjournald [jbd] 0x136
[<e08436b0>] commit_timeout [jbd] 0x0
[<c0107286>] kernel_thread [kernel] 0x26
[<e08436d0>] kjournald [jbd] 0x0

popper        D CEED5C00     0  4819   1104          4820  4807 (NOTLB)
Call Trace: [<c0107849>] __down [kernel] 0x69
[<c01079f8>] __down_failed [kernel] 0x8
[<c0160134>] .text.lock.dquot [kernel] 0x2d
[<c015e0bf>] dqget [kernel] 0x15f
[<e083edb8>] do_get_write_access [jbd] 0x568
[<c015eec6>] dquot_initialize [kernel] 0xa6
[<e084fe69>] ext3_new_inode [ext3] 0x8d9
[<e0847d10>] .rodata.str1.1 [jbd] 0x30
[<e08450f7>] __jbd_kmalloc [jbd] 0x27
[<e083e284>] start_this_handle [jbd] 0x124
[<e083e37d>] journal_start_Rsmp_89deb980 [jbd] 0xbd
[<e0854ad1>] ext3_create [ext3] 0x81
[<c014d600>] vfs_create [kernel] 0x130
[<c014d38a>] lookup_hash [kernel] 0x4a
[<c014d7ac>] open_namei [kernel] 0x13c
[<c0124c09>] timer_bh [kernel] 0x39
[<c0140f96>] filp_open [kernel] 0x36
[<c01412e4>] sys_open [kernel] 0x34
[<c0108c6b>] system_call [kernel] 0x33

kswapd        D DC0094A0  4128     7      1             8     6 (L-TLB)
Call Trace: [<c0118ecb>] sleep_on [kernel] 0x4b <--- locked by pid 197
[<e083e225>] start_this_handle [jbd] 0xc5
[<e083e37d>] journal_start_Rsmp_89deb980 [jbd] 0xbd
[<e085397e>] ext3_dirty_inode [ext3] 0x6e
[<c0139af8>] __alloc_pages [kernel] 0xa8        <--- spurious (on stack)
[<c0156f2e>] __mark_inode_dirty [kernel] 0x2e
[<c013225d>] generic_file_write [kernel] 0x34d
[<e084ed02>] ext3_file_write [ext3] 0x22
[<c015d37b>] write_dquot [kernel] 0xbb
[<c015de6c>] dqput [kernel] 0x8c
[<c015efdb>] dquot_drop [kernel] 0x3b
[<c0157b3e>] clear_inode [kernel] 0xce
[<c0156ded>] destroy_inode [kernel] 0x2d
[<c0157c2c>] dispose_list [kernel] 0x5c
[<c0157f73>] prune_icache [kernel] 0x143
[<c0157fb0>] shrink_icache_memory [kernel] 0x20
[<c0138856>] do_try_to_free_pages [kernel] 0x26
[<c0138b41>] kswapd [kernel] 0x101
[<c0105000>] stext [kernel] 0x0
[<c0107286>] kernel_thread [kernel] 0x26
[<c0138a40>] kswapd [kernel] 0x0

I reconstruct the sequence in the following way. The kswapd does its
trick and does the dquot_drop on some inode, taking a quota semaphore,
and manages to sleep somewhere a little (not exactly sure where,
perhaps writing a page out or something...). Next, popper goes
about ext3_create, does journal_start (we can even see a leftover
part of that sequence on its stack, no need to guess!), and
locks trying to grab the quote semaphore. Essentially, it sleeps
with ->t_updates incremented, and this is where the trouble starts.
kjournald is awaken, locks the current transaction with T_LOCKED and
waits for updates to drop (held by popper). To top things off,
the kswapd awakens or otherwise comes around and does journal_start,
which promptly blocks, because current t_state is T_LOCKED.

Now we have three processes, all locked together to form a deadlock,
which is kinda cute.
---------------------------------------------------------

Re: why isn't quota dependant on ext2?

[Andrew Morton]

Pete Zaitcev <zaitcev@redhat.com> wrote:
>
> >> > ext3, ufs and udf also use the core quota code.
> >> 
> >> The documentation says it only works with ext2 where would I find working
> >> utilities to get it working on ext3 ?
> > 
> > ext3 uses the same tools as ext2 - checkquota, quotaon, etc.
> > 
> > http://quota-tools.sourceforge.net/ (site seems to be broken)
> 
> The bad news is that quota on ext3 is virtually guaranteed
> to deadlock, so you can do it, but you do not want to do it.

Darnit, I had all that working 18 months ago ;)

> The original memo describes a deadlock in RH 2.4.18-5, which
> I assure you, was NOT fixed in Marcelo 2.4.20.

Yes, that's a common ext3 problem.  A journal_start()/journal_stop() pair is
the same, for locking purposes, as down()/up().  So they need to be ranked
consistently.

Let me crunch on that a bit...

Re: why isn't quota dependant on ext2?

[Gerhard Mack]

On Wed, 22 Jan 2003, Andrew Morton wrote:
> > >> > ext3, ufs and udf also use the core quota code.
> > >>
> > >> The documentation says it only works with ext2 where would I find working
> > >> utilities to get it working on ext3 ?
> > >
> > > ext3 uses the same tools as ext2 - checkquota, quotaon, etc.
> > >
> > > http://quota-tools.sourceforge.net/ (site seems to be broken)
> >
> > The bad news is that quota on ext3 is virtually guaranteed
> > to deadlock, so you can do it, but you do not want to do it.
>
> Darnit, I had all that working 18 months ago ;)
>
> > The original memo describes a deadlock in RH 2.4.18-5, which
> > I assure you, was NOT fixed in Marcelo 2.4.20.
>
> Yes, that's a common ext3 problem.  A journal_start()/journal_stop() pair is
> the same, for locking purposes, as down()/up().  So they need to be ranked
> consistently.
>
> Let me crunch on that a bit...
>

Thanks for the warning .. I was just about to restart my attempt at
sparc+ext3+quota.

	Gerhard

PS the help item for quota states that it only functions with ext2.


--
Gerhard Mack

gmack@innerfire.net

<>< As a computer I find your faith in technology amusing.

Re: why isn't quota dependant on ext2?

[Oleg Drokin]

Hello!

On Tue, Jan 21, 2003 at 08:47:53PM -0500, Gerhard Mack wrote:

> Anyone know why the quota menu option isn't dependant on ext2 since that's
> all it works with?

reiserfs works with this quota code too. Chris Mason working on porting the
patch from 2.4 to 2.5.

Bye,
    Oleg

Re: why isn't quota dependant on ext2?

[Jakob Oestergaard]

On Wed, Jan 22, 2003 at 04:05:55PM -0500, Pete Zaitcev wrote:
> >> > ext3, ufs and udf also use the core quota code.
> >> 
> >> The documentation says it only works with ext2 where would I find working
> >> utilities to get it working on ext3 ?
> > 
> > ext3 uses the same tools as ext2 - checkquota, quotaon, etc.
> > 
> > http://quota-tools.sourceforge.net/ (site seems to be broken)
> 
> The bad news is that quota on ext3 is virtually guaranteed
> to deadlock, so you can do it, but you do not want to do it.
> The original memo describes a deadlock in RH 2.4.18-5, which
> I assure you, was NOT fixed in Marcelo 2.4.20. A good anti-deadlock
> work was done, granted, but this particular one wasn't fixed.

Hmm... that doesn't match my experiences here...

[phoenix:joe] $ uname -r
2.4.20-rc3

[phoenix:joe] $ mount | grep exported
/dev/md7 on /exported type ext3 (rw,usrquota)

[phoenix:joe] $ df -h | grep expor
/dev/md7              147G   98G   41G  70% /exported

[phoenix:joe] $ df -ih | grep expor
/dev/md7                 19M    844k     17M    5% /exported

This is a fairly heavily loaded NFS server (load > 10 is not uncommon).

I have seen no lockups so far. Should I be worried ?

It uses the old quota format - could that be why it's ok ?

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