Re: ecryptfs_write_metadata: Error writing metadata out to lower file; rc = [-13]

[Tyler Hicks <tyhicks@canonical.com>]

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On 2011-12-19 13:26:19, Martin Steigerwald wrote:
> Hi!
> 
> Today I tested again whether ecryptfs would be suitable to replace encfs on my 
> laptop. But I found several problems. The blocking one is:

Sorry, hopefully we can get them straightened out.

> 
> ms@merkaba:~/Training/TXS-svn/Linux_15_Performance_Tuning#2> LANG=C make
> […]
> sed: couldn't open temporary file ./sedhqlAcd: Permission denied
> […]
> 
> ms@merkaba:~/Training/TXS-svn/Linux_15_Performance_Tuning> LANG=C ls -l | tail 
> -6
> ls: cannot access sedhqlAcd: No such file or directory
> ls: cannot access sedChky0a: No such file or directory
> ls: cannot access sed1eW8Ek: No such file or directory
> ls: cannot access sedEjR2oA: No such file or directory
> ls: cannot access sedb4JEiI: No such file or directory
> ls: cannot access sedy0KQnt: No such file or directory
> -?????????  ? ?  ?            ?            ? sedChky0a
> -?????????  ? ?  ?            ?            ? sedEjR2oA
> ----------  1 ms teamix 1143445 Dec  5 10:01 sedNL1bTk
> -?????????  ? ?  ?            ?            ? sedb4JEiI
> -?????????  ? ?  ?            ?            ? sedhqlAcd
> -?????????  ? ?  ?            ?            ? sedy0KQnt
> 
> 
> Output in dmesg is:
> 
> ms@merkaba:~/Training/TXS-svn/Linux_15_Performance_Tuning> sudo tail -2 
> /var/log/syslog
> Dec 19 13:23:30 merkaba kernel: [50999.570071] ecryptfs_write_metadata: Error 
> writing metadata out to lower file; rc = [-13]
> Dec 19 13:23:30 merkaba kernel: [50999.570083] Error writing headers; rc = 
> [-13]
> 
> 
> Ecryptfs is configured as follows:
> 
> merkaba:~> cat .ecryptfsrc
> ecryptfs_unlink_sigs
> ecryptfs_sig=[…]
> ecryptfs_fnek_sig=[…]
> ecryptfs_xattr
> ecryptfs_key_bytes=32
> ecryptfs_cipher=aes
> ecryptfs_passthrough=n
> 
> I am using extended attributes to avoid the space waste of 8 KiB per file.

I must warn you that the ecryptfs_xattr_metadata option is rarely used
by anyone and gets little testing from me upstream. I understand the
desire to save some space, but you should also consider stability here.
I'm working to automate some of that testing soon, so there is hope that
things could get better in this area.

> 
> The underlying filesystem is:
> 
> merkaba:~> grep /home /proc/mounts
> /dev/mapper/merkaba-home /home ext4 
> rw,noatime,user_xattr,acl,barrier=1,stripe=128,data=ordered 0 0
> /home/.ms /home/ms ecryptfs 
> rw,relatime,ecryptfs_fnek_sig=[…],ecryptfs_sig=[…],ecryptfs_cipher=aes,ecryptfs_key_bytes=32,ecryptfs_xattr_metadata,ecryptfs_unlink_sigs 
> 0 0
> 
> Kernel is:
> 
> ms@merkaba:~> cat /proc/version
> Linux version 3.2.0-rc4-amd64 (Debian 3.2~rc4-1~experimental.1) 

Ok, I was able to reproduce this on roughly the same kernel version by
untar'ing the kernel source.

I'll have to do some more investigation into how we can handle this
error better. ext4 is returning an error when we're trying to create the
xattr upon file creation, so how we convey that to userspace through the
creat() return value and how we clean up after ourselves is probably the
issue here.

Tyler

> (ben@decadent.org.uk) (gcc version 4.6.2 (Debian 4.6.2-5) ) #1 SMP Sun Dec 4 
> 18:38:24 UTC 2011
> 
> 
> With encfs or from my local workstation via NFS there is no such issue.
> 
> Ciao,
> -- 
> Martin Steigerwald - teamix GmbH - http://www.teamix.de
> gpg: 19E3 8D42 896F D004 08AC A0CA 1E10 C593 0399 AE90
> --
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