On Monday 06 of September 2010, Dave Chinner wrote:
> On Sun, Sep 05, 2010 at 07:24:35PM +0200, Arkadiusz Miskiewicz wrote:
> > * 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;
> >
> > }
>
> I don't think that is safe - we can have concurrent access to the
> in-core superblock (mp->m_sb) without locking the superblock, so
> something that races with xfs_mod_sb() looking up project quota
> could die a horrible death here.
I was thinking about working on a copy, too, like this
+ xfs_sb_t sb_copy;
[...]
+ memcpy(&sb_copy, from, sizeof(sb_copy));
+ from_ptr = (xfs_caddr_t)&sb_copy;
+
+ if (!xfs_sb_version_hasseparatepquota(from) &&
+ (sb_copy.sb_qflags & XFS_PQUOTA_ACCT)) {
+ sb_copy.sb_gquotino = from->sb_pquotino;
+ sb_copy.sb_pquotino = 0;
+
+ }
>
> The only time that you should need to do this juggling is when the
> quota inode changes. That is, when the XFS_SB_GQUOTINO field is
> set. Otherwise the field won't be modified and so we don't need to
> convert the values. That only occurs when quotas are being
> initialised (xfs_qm_qino_alloc()) during mount, so in that case
> there can't be any concurrent operations occurring. Hence swizzling
> the inode fields only when the XFS_SB_GQUOTINO filed is set should
> be safe.
Unfortunately it turns out that I need to convert sb_qflags, too (see below)
and sb_qflags seem to be changes in few different places, so xfs_mod_sb()
looks a good place to do a conversion for this.
sb_qflags come into play. Old XFS_OQUOTA_CHKD and
XFS_PQUOTA_CHKD are no longer used by kernel but existing filesystems
can have these, so I'm going to translate old into new flags currently
in xfs_sb_from_disk() and vice versa in xfs_mod_sb().
@@ -575,6 +588,26 @@ xfs_sb_from_disk(
to->sb_logsunit = be32_to_cpu(from->sb_logsunit);
to->sb_features2 = be32_to_cpu(from->sb_features2);
to->sb_bad_features2 = be32_to_cpu(from->sb_bad_features2);
+ to->sb_pquotino = be64_to_cpu(from->sb_pquotino);
+
+ /*
+ * Convert old quota to separatepquota flags.
+ */
+ if (to->sb_qflags & XFS_OQUOTA_CHKD_NOTUSED) {
+ if (to->sb_qflags & XFS_GQUOTA_ACCT) {
+ to->sb_qflags &= ~XFS_OQUOTA_CHKD_NOTUSED;
+ to->sb_qflags |= XFS_GQUOTA_CHKD;
+ } else if (to->sb_qflags & XFS_PQUOTA_ACCT) {
+ to->sb_qflags &= ~XFS_PQUOTA_CHKD_NOTUSED;
+ to->sb_qflags |= XFS_PQUOTA_CHKD;
+ }
+ }
+
+ if (!xfs_sb_version_hasseparatepquota(to) &&
+ (to->sb_qflags & XFS_PQUOTA_ACCT)) {
+ to->sb_pquotino = to->sb_gquotino;
+ to->sb_gquotino = 0;
+ }
}
New flags are going to be like this:
#define XFS_UQUOTA_ENFD 0x0002 /* user quota limits enforced */
#define XFS_UQUOTA_CHKD 0x0004 /* quotacheck run on usr quotas */
#define XFS_PQUOTA_ACCT 0x0008 /* project quota accounting ON */
-#define XFS_OQUOTA_ENFD 0x0010 /* other (grp/prj) quota limits enforced */
-#define XFS_OQUOTA_CHKD 0x0020 /* quotacheck run on other (grp/prj) quotas */
+#define XFS_OQUOTA_ENFD_NOTUSED 0x0010 /* other (grp/prj) quota limits enforced (NO LONGER USED)*/
+#define XFS_OQUOTA_CHKD_NOTUSED 0x0020 /* quotacheck run on other (grp/prj) quotas (NO LONGER USED)*/
#define XFS_GQUOTA_ACCT 0x0040 /* group quota accounting ON */
+#define XFS_GQUOTA_ENFD 0x0080 /* group quota limits enforced */
+#define XFS_GQUOTA_CHKD 0x0100 /* group quota accoungint ON */
+#define XFS_PQUOTA_CHKD 0x0200 /* quotacheck run on project quotas */
+#define XFS_PQUOTA_ENFD 0x0400 /* project quota limits enforced */
> Cheers,
>
> Dave.
--
Arkadiusz Miśkiewicz PLD/Linux Team
arekm / maven.pl http://ftp.pld-linux.org/
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