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xfs: simplify xfs_qm_dqattach_grouphint 

No need to play games with the qlock now that the freelist lock nests inside
it.  Also clean up various outdated comments.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
This commit is contained in:
Christoph Hellwig 2011-12-06 21:58:20 +00:00 committed by Ben Myers
parent bf72de3194
commit ab680bb739
1 changed files with 16 additions and 48 deletions
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64
fs/xfs/xfs_qm.c
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@ -650,11 +650,7 @@ xfs_qm_dqattach_one(
/*
* Given a udquot and gdquot, attach a ptr to the group dquot in the
* udquot as a hint for future lookups. The idea sounds simple, but the
* execution isn't, because the udquot might have a group dquot attached
* already and getting rid of that gets us into lock ordering constraints.
* The process is complicated more by the fact that the dquots may or may not
* be locked on entry.
* udquot as a hint for future lookups.
*/
STATIC void
xfs_qm_dqattach_grouphint(
@ -665,45 +661,21 @@ xfs_qm_dqattach_grouphint(
xfs_dqlock(udq);
if ((tmp = udq->q_gdquot)) {
if (tmp == gdq) {
xfs_dqunlock(udq);
return;
}
tmp = udq->q_gdquot;
if (tmp) {
if (tmp == gdq)
goto done;
udq->q_gdquot = NULL;
/*
* We can't keep any dqlocks when calling dqrele,
* because the freelist lock comes before dqlocks.
*/
xfs_dqunlock(udq);
/*
* we took a hard reference once upon a time in dqget,
* so give it back when the udquot no longer points at it
* dqput() does the unlocking of the dquot.
*/
xfs_qm_dqrele(tmp);
xfs_dqlock(udq);
xfs_dqlock(gdq);
} else {
ASSERT(XFS_DQ_IS_LOCKED(udq));
xfs_dqlock(gdq);
}
ASSERT(XFS_DQ_IS_LOCKED(udq));
ASSERT(XFS_DQ_IS_LOCKED(gdq));
/*
* Somebody could have attached a gdquot here,
* when we dropped the uqlock. If so, just do nothing.
*/
if (udq->q_gdquot == NULL) {
XFS_DQHOLD(gdq);
udq->q_gdquot = gdq;
}
xfs_dqlock(gdq);
XFS_DQHOLD(gdq);
xfs_dqunlock(gdq);
udq->q_gdquot = gdq;
done:
xfs_dqunlock(udq);
}
@ -770,17 +742,13 @@ xfs_qm_dqattach_locked(
ASSERT(ip->i_gdquot);
/*
* We may or may not have the i_udquot locked at this point,
* but this check is OK since we don't depend on the i_gdquot to
* be accurate 100% all the time. It is just a hint, and this
* will succeed in general.
* We do not have i_udquot locked at this point, but this check
* is OK since we don't depend on the i_gdquot to be accurate
* 100% all the time. It is just a hint, and this will
* succeed in general.
*/
if (ip->i_udquot->q_gdquot == ip->i_gdquot)
goto done;
/*
* Attach i_gdquot to the gdquot hint inside the i_udquot.
*/
xfs_qm_dqattach_grouphint(ip->i_udquot, ip->i_gdquot);
if (ip->i_udquot->q_gdquot != ip->i_gdquot)
xfs_qm_dqattach_grouphint(ip->i_udquot, ip->i_gdquot);
}
done: