Re: ext4+quota+nfs issue

From: Pavol Cvengros
Date: Wed Sep 09 2009 - 13:20:13 EST


On 9/9/2009 4:46 PM, Jan Kara wrote:
On Wed 09-09-09 11:42:03, Jiri Kosina wrote:
[ adding relevant CCs ]
Thanks.

On Wed, 9 Sep 2009, Pavol Cvengros wrote:
recently we have build and started to use raid storage with formatted
capacity of 4.5T (ext4 formatted, default params).
FS has quota turned on and is exported via NFS to nodes.
If we turn qouta on on this FS and are trying to use it over NFS we get the
following:

------------[ cut here ]------------
WARNING: at fs/quota/dquot.c:964 dquot_claim_space+0x181/0x190()
Hardware name: S3210SH
Modules linked in: nfs fscache nfsd lockd auth_rpcgss exportfs sunrpc
coretemp hwmon ipmi_si ipmi_msghandler ehci_hcd sr_mod cdrom uhci_hcd floppy
usbcore i2c_i801 i2c_core processor 3w_9xxx button thermal
Pid: 268, comm: pdflush Tainted: G W 2.6.30-gentoo-r3_host #1
Call Trace:
[<ffffffff803151e1>] ? dquot_claim_space+0x181/0x190
[<ffffffff80245c59>] ? warn_slowpath_common+0x89/0x100
[<ffffffff803151e1>] ? dquot_claim_space+0x181/0x190
[<ffffffff80367e83>] ? ext4_mb_mark_diskspace_used+0x423/0x440
[<ffffffff8036c05f>] ? ext4_mb_new_blocks+0x2cf/0x460
[<ffffffff80360a17>] ? ext4_ext_find_extent+0x307/0x330
[<ffffffff80362508>] ? ext4_ext_get_blocks+0x578/0xfc0
[<ffffffff8028e828>] ? __pagevec_free+0x48/0x70
[<ffffffff803a1c65>] ? blk_rq_bio_prep+0x35/0x130
[<ffffffff8034d310>] ? ext4_get_blocks_wrap+0x210/0x380
[<ffffffff8034d8d8>] ? mpage_da_map_blocks+0xe8/0x750
[<ffffffff80292cee>] ? pagevec_lookup_tag+0x2e/0x50
[<ffffffff8029084c>] ? write_cache_pages+0x11c/0x400
[<ffffffff8034e500>] ? __mpage_da_writepage+0x0/0x190
[<ffffffff8034e269>] ? ext4_da_writepages+0x329/0x4b0
[<ffffffff80290bd2>] ? do_writepages+0x32/0x70
[<ffffffff802e4140>] ? __writeback_single_inode+0xb0/0x490
[<ffffffff8023c753>] ? dequeue_entity+0x23/0x1c0
[<ffffffff802e4b16>] ? generic_sync_sb_inodes+0x316/0x4f0
[<ffffffff802e4f4e>] ? writeback_inodes+0x5e/0x110
[<ffffffff80290e56>] ? wb_kupdate+0xc6/0x160
[<ffffffff80292110>] ? pdflush+0x120/0x230
[<ffffffff80290d90>] ? wb_kupdate+0x0/0x160
[<ffffffff80291ff0>] ? pdflush+0x0/0x230
[<ffffffff80261154>] ? kthread+0x64/0xc0
[<ffffffff8020d13a>] ? child_rip+0xa/0x20
[<ffffffff802610f0>] ? kthread+0x0/0xc0
[<ffffffff8020d130>] ? child_rip+0x0/0x20
---[ end trace cb54e6523e9ab60d ]---

fstab entry:
/dev/sdb1 /mnt/storage ext4
noatime,nodiratime,usrjquota=aquota.user,grpjquota=aquota.group,jqfmt=vfsv0

qith quotaoff on tihs FS, warnings stop.

Question is if it's safe to use quotas with this problem (warning) or not.
Can't afford data damage.
The warning definitely doesn't directly indicate a danger of data loss.
But there *is* some bug causing that ext4 asks for more quota space than
it has reserved.
From your report it seems it is easily reproducible, right? Do you have
an easy way to trigger this warning - by some test script or so?

Honza
really easy to reproduce, our storage is on live production so I can't experiment with kernel but it's enough to do quotaon and system will get "spammed" with these warning on every file access..

P.

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