Re: [patch 15/19] xfs: simplify xfs_qm_detach_gdquots

Ben Myers
2011-12-15T16:42:50Z

On Tue, Dec 06, 2011 at 04:58:21PM -0500, Christoph Hellwig wrote:
> There is no reason to drop qi_dqlist_lock around calls to xfs_qm_dqrele
> because the free list lock now nests inside qi_dqlist_lock and the
> dquot lock.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Reviewed-by: Dave Chinner <dchinner@redhat.com>
>
> ---
> fs/xfs/xfs_qm.c | 22 +++++-----------------
> 1 file changed, 5 insertions(+), 17 deletions(-)
>
> Index: xfs/fs/xfs/xfs_qm.c
> ===================================================================
> --- xfs.orig/fs/xfs/xfs_qm.c 2011-10-27 22:40:07.538179215 +0200
> +++ xfs/fs/xfs/xfs_qm.c 2011-10-27 22:40:08.124671538 +0200
> @@ -449,7 +449,6 @@ xfs_qm_detach_gdquots(
> {
> struct xfs_quotainfo *q = mp->m_quotainfo;
> struct xfs_dquot *dqp, *gdqp;
> - int nrecl;
>
> again:
> ASSERT(mutex_is_locked(&q->qi_dqlist_lock));
> @@ -462,25 +461,14 @@ xfs_qm_detach_gdquots(
> mutex_lock(&q->qi_dqlist_lock);
> goto again;
> }
> - if ((gdqp = dqp->q_gdquot)) {
> - xfs_dqlock(gdqp);

Why don't we need to take the dqlock on gdqp here before dropping the
lock on dqp?

> +
> + gdqp = dqp->q_gdquot;
> + if (gdqp)
> dqp->q_gdquot = NULL;
> - }
> xfs_dqunlock(dqp);
>
> - if (gdqp) {
> - /*
> - * Can't hold the mplist lock across a dqput.
> - * XXXmust convert to marker based iterations here.
> - */
> - nrecl = q->qi_dqreclaims;
> - mutex_unlock(&q->qi_dqlist_lock);
> - xfs_qm_dqput(gdqp);
> -
> - mutex_lock(&q->qi_dqlist_lock);
> - if (nrecl != q->qi_dqreclaims)

Why is it ok to ignore di_dqreclaims now?

> - goto again;
> - }
> + if (gdqp)
> + xfs_qm_dqrele(gdqp);
> }
> }
>
>
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