xfs: remove duplicate code from dquot reclaim

The dquot shaker and the free-list reclaim code use exactly the same
algorithm but the code is duplicated and slightly different in each
case. Make the shaker code use the single dquot reclaim code to
remove the code duplication.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

fs/xfs/linux-2.6/xfs_trace.h

@@ -653,8 +653,6 @@ DEFINE_EVENT(xfs_dquot_class, name, \
 	TP_PROTO(struct xfs_dquot *dqp), \
 	TP_ARGS(dqp))
 DEFINE_DQUOT_EVENT(xfs_dqadjust);
-DEFINE_DQUOT_EVENT(xfs_dqshake_dirty);
-DEFINE_DQUOT_EVENT(xfs_dqshake_unlink);
 DEFINE_DQUOT_EVENT(xfs_dqreclaim_want);
 DEFINE_DQUOT_EVENT(xfs_dqreclaim_dirty);
 DEFINE_DQUOT_EVENT(xfs_dqreclaim_unlink);

fs/xfs/quota/xfs_qm.c

@@ -1926,194 +1926,6 @@ xfs_qm_init_quotainos(
 }
 
 
-/*
- * Traverse the freelist of dquots and attempt to reclaim a maximum of
- * 'howmany' dquots. This operation races with dqlookup(), and attempts to
- * favor the lookup function ...
- * XXXsup merge this with qm_reclaim_one().
- */
-STATIC int
-xfs_qm_shake_freelist(
-	int howmany)
-{
-	int		nreclaimed;
-	xfs_dqhash_t	*hash;
-	xfs_dquot_t	*dqp, *nextdqp;
-	int		restarts;
-	int		nflushes;
-
-	if (howmany <= 0)
-		return 0;
-
-	nreclaimed = 0;
-	restarts = 0;
-	nflushes = 0;
-
-#ifdef QUOTADEBUG
-	cmn_err(CE_DEBUG, "Shake free 0x%x", howmany);
-#endif
-	/* lock order is : hashchainlock, freelistlock, mplistlock */
- tryagain:
-	xfs_qm_freelist_lock(xfs_Gqm);
-
-	for (dqp = xfs_Gqm->qm_dqfreelist.qh_next;
-	     ((dqp != (xfs_dquot_t *) &xfs_Gqm->qm_dqfreelist) &&
-	      nreclaimed < howmany); ) {
-		struct xfs_mount *mp = dqp->q_mount;
-		xfs_dqlock(dqp);
-
-		/*
-		 * We are racing with dqlookup here. Naturally we don't
-		 * want to reclaim a dquot that lookup wants.
-		 */
-		if (dqp->dq_flags & XFS_DQ_WANT) {
-			xfs_dqunlock(dqp);
-			xfs_qm_freelist_unlock(xfs_Gqm);
-			if (++restarts >= XFS_QM_RECLAIM_MAX_RESTARTS)
-				return nreclaimed;
-			XQM_STATS_INC(xqmstats.xs_qm_dqwants);
-			goto tryagain;
-		}
-
-		/*
-		 * If the dquot is inactive, we are assured that it is
-		 * not on the mplist or the hashlist, and that makes our
-		 * life easier.
-		 */
-		if (dqp->dq_flags & XFS_DQ_INACTIVE) {
-			ASSERT(mp == NULL);
-			ASSERT(! XFS_DQ_IS_DIRTY(dqp));
-			ASSERT(dqp->HL_PREVP == NULL);
-			ASSERT(list_empty(&dqp->q_mplist));
-			XQM_STATS_INC(xqmstats.xs_qm_dqinact_reclaims);
-			nextdqp = dqp->dq_flnext;
-			goto off_freelist;
-		}
-
-		ASSERT(!list_empty(&dqp->q_mplist));
-		/*
-		 * Try to grab the flush lock. If this dquot is in the process of
-		 * getting flushed to disk, we don't want to reclaim it.
-		 */
-		if (!xfs_dqflock_nowait(dqp)) {
-			xfs_dqunlock(dqp);
-			dqp = dqp->dq_flnext;
-			continue;
-		}
-
-		/*
-		 * We have the flush lock so we know that this is not in the
-		 * process of being flushed. So, if this is dirty, flush it
-		 * DELWRI so that we don't get a freelist infested with
-		 * dirty dquots.
-		 */
-		if (XFS_DQ_IS_DIRTY(dqp)) {
-			int	error;
-
-			trace_xfs_dqshake_dirty(dqp);
-
-			/*
-			 * We flush it delayed write, so don't bother
-			 * releasing the mplock.
-			 */
-			error = xfs_qm_dqflush(dqp, 0);
-			if (error) {
-				xfs_fs_cmn_err(CE_WARN, mp,
-			"xfs_qm_dqflush_all: dquot %p flush failed", dqp);
-			}
-			xfs_dqunlock(dqp); /* dqflush unlocks dqflock */
-			dqp = dqp->dq_flnext;
-			continue;
-		}
-		/*
-		 * We're trying to get the hashlock out of order. This races
-		 * with dqlookup; so, we giveup and goto the next dquot if
-		 * we couldn't get the hashlock. This way, we won't starve
-		 * a dqlookup process that holds the hashlock that is
-		 * waiting for the freelist lock.
-		 */
-		if (!mutex_trylock(&dqp->q_hash->qh_lock)) {
-			xfs_dqfunlock(dqp);
-			xfs_dqunlock(dqp);
-			dqp = dqp->dq_flnext;
-			continue;
-		}
-		/*
-		 * This races with dquot allocation code as well as dqflush_all
-		 * and reclaim code. So, if we failed to grab the mplist lock,
-		 * giveup everything and start over.
-		 */
-		hash = dqp->q_hash;
-		ASSERT(hash);
-		if (!mutex_trylock(&mp->m_quotainfo->qi_dqlist_lock)) {
-			/* XXX put a sentinel so that we can come back here */
-			xfs_dqfunlock(dqp);
-			xfs_dqunlock(dqp);
-			mutex_unlock(&hash->qh_lock);
-			xfs_qm_freelist_unlock(xfs_Gqm);
-			if (++restarts >= XFS_QM_RECLAIM_MAX_RESTARTS)
-				return nreclaimed;
-			goto tryagain;
-		}
-
-		trace_xfs_dqshake_unlink(dqp);
-
-#ifdef QUOTADEBUG
-		cmn_err(CE_DEBUG, "Shake 0x%p, ID 0x%x\n",
-			dqp, be32_to_cpu(dqp->q_core.d_id));
-#endif
-		ASSERT(dqp->q_nrefs == 0);
-		nextdqp = dqp->dq_flnext;
-		XQM_HASHLIST_REMOVE(hash, dqp);
-		list_del_init(&dqp->q_mplist);
-		mp->m_quotainfo->qi_dquots--;
-		mp->m_quotainfo->qi_dqreclaims++;
-		xfs_dqfunlock(dqp);
-		mutex_unlock(&mp->m_quotainfo->qi_dqlist_lock);
-		mutex_unlock(&hash->qh_lock);
-
- off_freelist:
-		XQM_FREELIST_REMOVE(dqp);
-		xfs_dqunlock(dqp);
-		nreclaimed++;
-		XQM_STATS_INC(xqmstats.xs_qm_dqshake_reclaims);
-		xfs_qm_dqdestroy(dqp);
-		dqp = nextdqp;
-	}
-	xfs_qm_freelist_unlock(xfs_Gqm);
-	return nreclaimed;
-}
-
-
-/*
- * The kmem_shake interface is invoked when memory is running low.
- */
-/* ARGSUSED */
-STATIC int
-xfs_qm_shake(int nr_to_scan, gfp_t gfp_mask)
-{
-	int	ndqused, nfree, n;
-
-	if (!kmem_shake_allow(gfp_mask))
-		return 0;
-	if (!xfs_Gqm)
-		return 0;
-
-	nfree = xfs_Gqm->qm_dqfreelist.qh_nelems; /* free dquots */
-	/* incore dquots in all f/s's */
-	ndqused = atomic_read(&xfs_Gqm->qm_totaldquots) - nfree;
-
-	ASSERT(ndqused >= 0);
-
-	if (nfree <= ndqused && nfree < ndquot)
-		return 0;
-
-	ndqused *= xfs_Gqm->qm_dqfree_ratio;	/* target # of free dquots */
-	n = nfree - ndqused - ndquot;		/* # over target */
-
-	return xfs_qm_shake_freelist(MAX(nfree, n));
-}
-
 
 /*
  * Just pop the least recently used dquot off the freelist and
@@ -2125,14 +1937,12 @@ xfs_qm_dqreclaim_one(void)
 	xfs_dquot_t	*dqpout;
 	xfs_dquot_t	*dqp;
 	int		restarts;
-	int		nflushes;
 
 	restarts = 0;
 	dqpout = NULL;
-	nflushes = 0;
 
 	/* lockorder: hashchainlock, freelistlock, mplistlock, dqlock, dqflock */
- startagain:
+startagain:
 	xfs_qm_freelist_lock(xfs_Gqm);
 
 	FOREACH_DQUOT_IN_FREELIST(dqp, &(xfs_Gqm->qm_dqfreelist)) {
@@ -2211,16 +2021,33 @@ xfs_qm_dqreclaim_one(void)
 			continue;
 		}
 
-		if (!mutex_trylock(&mp->m_quotainfo->qi_dqlist_lock)) {
+		/*
-			xfs_dqfunlock(dqp);
+		 * We're trying to get the hashlock out of order. This races
-			xfs_dqunlock(dqp);
+		 * with dqlookup; so, we giveup and goto the next dquot if
-			continue;
+		 * we couldn't get the hashlock. This way, we won't starve
+		 * a dqlookup process that holds the hashlock that is
+		 * waiting for the freelist lock.
+		 */
+		if (!mutex_trylock(&dqp->q_hash->qh_lock)) {
+			restarts++;
+			goto dqfunlock;
 		}
 
-		if (!mutex_trylock(&dqp->q_hash->qh_lock))
+		/*
-			goto mplistunlock;
+		 * This races with dquot allocation code as well as dqflush_all
-
+		 * and reclaim code. So, if we failed to grab the mplist lock,
-		trace_xfs_dqreclaim_unlink(dqp);
+		 * giveup everything and start over.
+		 */
+		if (!mutex_trylock(&mp->m_quotainfo->qi_dqlist_lock)) {
+			restarts++;
+			mutex_unlock(&dqp->q_hash->qh_lock);
+			xfs_dqfunlock(dqp);
+			xfs_dqunlock(dqp);
+			xfs_qm_freelist_unlock(xfs_Gqm);
+			if (restarts++ >= XFS_QM_RECLAIM_MAX_RESTARTS)
+				return NULL;
+			goto startagain;
+		}
 
 		ASSERT(dqp->q_nrefs == 0);
 		list_del_init(&dqp->q_mplist);
@@ -2229,19 +2056,74 @@ xfs_qm_dqreclaim_one(void)
 		XQM_HASHLIST_REMOVE(dqp->q_hash, dqp);
 		XQM_FREELIST_REMOVE(dqp);
 		dqpout = dqp;
-		mutex_unlock(&dqp->q_hash->qh_lock);
- mplistunlock:
 		mutex_unlock(&mp->m_quotainfo->qi_dqlist_lock);
+		mutex_unlock(&dqp->q_hash->qh_lock);
+dqfunlock:
 		xfs_dqfunlock(dqp);
 		xfs_dqunlock(dqp);
 		if (dqpout)
 			break;
+		if (restarts >= XFS_QM_RECLAIM_MAX_RESTARTS)
+			return NULL;
 	}
-
 	xfs_qm_freelist_unlock(xfs_Gqm);
 	return dqpout;
 }
 
+/*
+ * Traverse the freelist of dquots and attempt to reclaim a maximum of
+ * 'howmany' dquots. This operation races with dqlookup(), and attempts to
+ * favor the lookup function ...
+ */
+STATIC int
+xfs_qm_shake_freelist(
+	int	howmany)
+{
+	int		nreclaimed = 0;
+	xfs_dquot_t	*dqp;
+
+	if (howmany <= 0)
+		return 0;
+
+	while (nreclaimed < howmany) {
+		dqp = xfs_qm_dqreclaim_one();
+		if (!dqp)
+			return nreclaimed;
+		xfs_qm_dqdestroy(dqp);
+		nreclaimed++;
+	}
+	return nreclaimed;
+}
+
+/*
+ * The kmem_shake interface is invoked when memory is running low.
+ */
+/* ARGSUSED */
+STATIC int
+xfs_qm_shake(int nr_to_scan, gfp_t gfp_mask)
+{
+	int	ndqused, nfree, n;
+
+	if (!kmem_shake_allow(gfp_mask))
+		return 0;
+	if (!xfs_Gqm)
+		return 0;
+
+	nfree = xfs_Gqm->qm_dqfreelist.qh_nelems; /* free dquots */
+	/* incore dquots in all f/s's */
+	ndqused = atomic_read(&xfs_Gqm->qm_totaldquots) - nfree;
+
+	ASSERT(ndqused >= 0);
+
+	if (nfree <= ndqused && nfree < ndquot)
+		return 0;
+
+	ndqused *= xfs_Gqm->qm_dqfree_ratio;	/* target # of free dquots */
+	n = nfree - ndqused - ndquot;		/* # over target */
+
+	return xfs_qm_shake_freelist(MAX(nfree, n));
+}
+
 
 /*------------------------------------------------------------------*/