On Sunday 05 of September 2010, Christoph Hellwig wrote:
> Thanks for doing this work Arek, I think it will be useful for some
> users and defintively is cleaners than what we have now.
>
> > I started doing that by splitting every group+project handling code into
> > separate group and project one. Added superblock field for project quota.
> > New feature flag (SEPARATEPQUOTA).
>
> Ok.
>
> > If old filesystem (for SEPARATEQUOTA) is mounted then I'll simply load
> > sb_gquotino into mp->m_sb.sb_pquotino which I think is enough to handle
> > old fs (since new kernel operates on separate structures for project
> > quota).
>
> Do you mean an old filesystem without the SEPARATEQUOTA bit set here?
Yes. When trying to load existing project quota inode in
xfs_qm_init_quotainos() I'm doing:
+ if (!xfs_sb_version_hasseparatepquota(&mp->m_sb)) {
+ ASSERT(!XFS_IS_GQUOTA_ON(mp));
+ mp->m_sb.sb_pquotino = mp->m_sb.sb_gquotino;
+ mp->m_sb.sb_gquotino = 0;
+ }
While xfs_mod_sb() now does:
/*
* Filesystem has no separatepquota turned on,
* so we need to store project quota in group
* quota inode on disk.
*/
if (!xfs_sb_version_hasseparatepquota(&mp->m_sb)) {
mp->m_sb.sb_gquotino = mp->m_sb.sb_pquotino;
mp->m_sb.sb_pquotino = 0;
}
xfs_sb_to_disk(XFS_BUF_TO_SBP(bp), &mp->m_sb, fields);
[...]
/*
* Restore original in-memory project quota inode state.
*/
if (!xfs_sb_version_hasseparatepquota(&mp->m_sb)) {
mp->m_sb.sb_pquotino = mp->m_sb.sb_gquotino;
mp->m_sb.sb_gquotino = 0;
}
so in-memory sb_pquotaino is always used for project quota (regardless of
SEPARATEPQUOTA feature) while on-disk is depending on SEPARATEPQUOTA feature
bit. SB modify part is untested yet.
> > Converting old fs to separate quota isn't currently solved. User could
> > need two choices - use old group quota still as group or old group as
> > new project quota. Not sure how to handle these yet.
>
> We know what sb_gquotino is used for currently from sb_qflags. If it's
> used for group quota we can simply set the SEPARATEQUOTA bit and we're
> done. To convert a filesystem using project quotas to SEPARATEQUOTA
> sb_gquotino needs to be cleared and instead the new sb_pquotino field
> needs to point to the project quota inode.
Ok, I'll add new "upgrade <feature>" command to xfs_db (and call it from
xfs_admin, too) where for now the only feature will be "separatepquota" one.
--
Arkadiusz Miśkiewicz PLD/Linux Team
arekm / maven.pl http://ftp.pld-linux.org/
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