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[PATCH 5/8] xfs: per-filesystem dquot LRU lists

To: xfs@xxxxxxxxxxx
Subject: [PATCH 5/8] xfs: per-filesystem dquot LRU lists
From: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Date: Sun, 19 Feb 2012 21:28:20 -0500
References: <20120220022815.018921977@xxxxxxxxxxxxxxxxxxxxxx>
User-agent: quilt/0.48-1
Replace the global dquot lru lists with a per-filesystem one.

Note that the shrinker isn't wire up to the per-superblock VFS shrinker
infrastructure as would have problems summing up and splitting the counts
for inodes and dquots.  I don't think this is a major problem as the quota
cache isn't as interwinded with the inode cache as the dentry cache is,
because an inode that is dropped from the cache will generally release
a dquot reference, but most of the time it won't be the last one.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>

---
 fs/xfs/xfs_dquot.c |   85 +++++++++++++++++++++++++++--------------------------
 fs/xfs/xfs_dquot.h |    2 -
 fs/xfs/xfs_qm.c    |   59 +++++++++++++++---------------------
 fs/xfs/xfs_qm.h    |    7 ++--
 4 files changed, 74 insertions(+), 79 deletions(-)

Index: xfs/fs/xfs/xfs_dquot.c
===================================================================
--- xfs.orig/fs/xfs/xfs_dquot.c 2012-02-17 19:11:41.000000000 -0800
+++ xfs/fs/xfs/xfs_dquot.c      2012-02-17 19:17:23.773327994 -0800
@@ -47,7 +47,7 @@
  *     qi->qi_dqlist_lock
  *       dquot->q_qlock (xfs_dqlock() and friends)
  *         dquot->q_flush (xfs_dqflock() and friends)
- *         xfs_Gqm->qm_dqfrlist_lock
+ *         qi->qi_lru_lock
  *
  * If two dquots need to be locked the order is user before group/project,
  * otherwise by the lowest id first, see xfs_dqlock2.
@@ -69,7 +69,7 @@ void
 xfs_qm_dqdestroy(
        xfs_dquot_t     *dqp)
 {
-       ASSERT(list_empty(&dqp->q_freelist));
+       ASSERT(list_empty(&dqp->q_lru));
 
        mutex_destroy(&dqp->q_qlock);
        kmem_zone_free(xfs_Gqm->qm_dqzone, dqp);
@@ -497,7 +497,7 @@ xfs_qm_dqread(
        dqp->dq_flags = type;
        dqp->q_core.d_id = cpu_to_be32(id);
        dqp->q_mount = mp;
-       INIT_LIST_HEAD(&dqp->q_freelist);
+       INIT_LIST_HEAD(&dqp->q_lru);
        mutex_init(&dqp->q_qlock);
        init_waitqueue_head(&dqp->q_pinwait);
 
@@ -844,38 +844,22 @@ restart:
 }
 
 
-/*
- * Release a reference to the dquot (decrement ref-count)
- * and unlock it. If there is a group quota attached to this
- * dquot, carefully release that too without tripping over
- * deadlocks'n'stuff.
- */
-void
-xfs_qm_dqput(
+STATIC void
+xfs_qm_dqput_final(
        struct xfs_dquot        *dqp)
 {
+       struct xfs_quotainfo    *qi = dqp->q_mount->m_quotainfo;
        struct xfs_dquot        *gdqp;
 
-       ASSERT(dqp->q_nrefs > 0);
-       ASSERT(XFS_DQ_IS_LOCKED(dqp));
-
-       trace_xfs_dqput(dqp);
-
-recurse:
-       if (--dqp->q_nrefs > 0) {
-               xfs_dqunlock(dqp);
-               return;
-       }
-
        trace_xfs_dqput_free(dqp);
 
-       mutex_lock(&xfs_Gqm->qm_dqfrlist_lock);
-       if (list_empty(&dqp->q_freelist)) {
-               list_add_tail(&dqp->q_freelist, &xfs_Gqm->qm_dqfrlist);
-               xfs_Gqm->qm_dqfrlist_cnt++;
+       mutex_lock(&qi->qi_lru_lock);
+       if (list_empty(&dqp->q_lru)) {
+               list_add_tail(&dqp->q_lru, &qi->qi_lru_list);
+               qi->qi_lru_count++;
                XFS_STATS_INC(xs_qm_dquot_unused);
        }
-       mutex_unlock(&xfs_Gqm->qm_dqfrlist_lock);
+       mutex_unlock(&qi->qi_lru_lock);
 
        /*
         * If we just added a udquot to the freelist, then we want to release
@@ -892,10 +876,29 @@ recurse:
        /*
         * If we had a group quota hint, release it now.
         */
-       if (gdqp) {
-               dqp = gdqp;
-               goto recurse;
-       }
+       if (gdqp)
+               xfs_qm_dqput(gdqp);
+}
+
+/*
+ * Release a reference to the dquot (decrement ref-count) and unlock it.
+ *
+ * If there is a group quota attached to this dquot, carefully release that
+ * too without tripping over deadlocks'n'stuff.
+ */
+void
+xfs_qm_dqput(
+       struct xfs_dquot        *dqp)
+{
+       ASSERT(dqp->q_nrefs > 0);
+       ASSERT(XFS_DQ_IS_LOCKED(dqp));
+
+       trace_xfs_dqput(dqp);
+
+       if (--dqp->q_nrefs > 0)
+               xfs_dqunlock(dqp);
+       else
+               xfs_qm_dqput_final(dqp);
 }
 
 /*
@@ -1126,6 +1129,7 @@ xfs_qm_dqpurge(
 {
        struct xfs_mount        *mp = dqp->q_mount;
        struct xfs_dqhash       *qh = dqp->q_hash;
+       struct xfs_quotainfo    *qi = mp->m_quotainfo;
 
        xfs_dqlock(dqp);
 
@@ -1176,22 +1180,21 @@ xfs_qm_dqpurge(
        qh->qh_version++;
        mutex_unlock(&qh->qh_lock);
 
-       mutex_lock(&mp->m_quotainfo->qi_dqlist_lock);
+       mutex_lock(&qi->qi_dqlist_lock);
        list_del_init(&dqp->q_mplist);
-       mp->m_quotainfo->qi_dqreclaims++;
-       mp->m_quotainfo->qi_dquots--;
-       mutex_unlock(&mp->m_quotainfo->qi_dqlist_lock);
+       qi->qi_dqreclaims++;
+       qi->qi_dquots--;
+       mutex_unlock(&qi->qi_dqlist_lock);
 
        /*
         * We move dquots to the freelist as soon as their reference count
         * hits zero, so it really should be on the freelist here.
         */
-       mutex_lock(&xfs_Gqm->qm_dqfrlist_lock);
-       ASSERT(!list_empty(&dqp->q_freelist));
-       list_del_init(&dqp->q_freelist);
-       xfs_Gqm->qm_dqfrlist_cnt--;
-       XFS_STATS_DEC(xs_qm_dquot_unused);
-       mutex_unlock(&xfs_Gqm->qm_dqfrlist_lock);
+       mutex_lock(&qi->qi_lru_lock);
+       ASSERT(!list_empty(&dqp->q_lru));
+       list_del_init(&dqp->q_lru);
+       qi->qi_lru_count--;
+       mutex_unlock(&qi->qi_lru_lock);
 
        xfs_qm_dqdestroy(dqp);
 }
Index: xfs/fs/xfs/xfs_dquot.h
===================================================================
--- xfs.orig/fs/xfs/xfs_dquot.h 2012-02-17 18:45:50.000000000 -0800
+++ xfs/fs/xfs/xfs_dquot.h      2012-02-17 19:13:51.929995233 -0800
@@ -47,7 +47,7 @@ struct xfs_trans;
  */
 typedef struct xfs_dquot {
        uint             dq_flags;      /* various flags (XFS_DQ_*) */
-       struct list_head q_freelist;    /* global free list of dquots */
+       struct list_head q_lru;         /* global free list of dquots */
        struct list_head q_mplist;      /* mount's list of dquots */
        struct list_head q_hashlist;    /* gloabl hash list of dquots */
        xfs_dqhash_t    *q_hash;        /* the hashchain header */
Index: xfs/fs/xfs/xfs_qm.c
===================================================================
--- xfs.orig/fs/xfs/xfs_qm.c    2012-02-17 19:11:57.693328883 -0800
+++ xfs/fs/xfs/xfs_qm.c 2012-02-17 19:18:07.813328143 -0800
@@ -61,11 +61,6 @@ STATIC int   xfs_qm_init_quotainos(xfs_mou
 STATIC int     xfs_qm_init_quotainfo(xfs_mount_t *);
 STATIC int     xfs_qm_shake(struct shrinker *, struct shrink_control *);
 
-static struct shrinker xfs_qm_shaker = {
-       .shrink = xfs_qm_shake,
-       .seeks = DEFAULT_SEEKS,
-};
-
 /*
  * Initialize the XQM structure.
  * Note that there is not one quota manager per file system.
@@ -106,13 +101,6 @@ xfs_Gqm_init(void)
        }
 
        /*
-        * Freelist of all dquots of all file systems
-        */
-       INIT_LIST_HEAD(&xqm->qm_dqfrlist);
-       xqm->qm_dqfrlist_cnt = 0;
-       mutex_init(&xqm->qm_dqfrlist_lock);
-
-       /*
         * dquot zone. we register our own low-memory callback.
         */
        if (!qm_dqzone) {
@@ -122,8 +110,6 @@ xfs_Gqm_init(void)
        } else
                xqm->qm_dqzone = qm_dqzone;
 
-       register_shrinker(&xfs_qm_shaker);
-
        /*
         * The t_dqinfo portion of transactions.
         */
@@ -155,12 +141,6 @@ xfs_qm_destroy(
        ASSERT(xqm != NULL);
        ASSERT(xqm->qm_nrefs == 0);
 
-       unregister_shrinker(&xfs_qm_shaker);
-
-       mutex_lock(&xqm->qm_dqfrlist_lock);
-       ASSERT(list_empty(&xqm->qm_dqfrlist));
-       mutex_unlock(&xqm->qm_dqfrlist_lock);
-
        hsize = xqm->qm_dqhashmask + 1;
        for (i = 0; i < hsize; i++) {
                xfs_qm_list_destroy(&(xqm->qm_usr_dqhtable[i]));
@@ -826,6 +806,10 @@ xfs_qm_init_quotainfo(
        mutex_init(&qinf->qi_dqlist_lock);
        lockdep_set_class(&qinf->qi_dqlist_lock, &xfs_quota_mplist_class);
 
+       INIT_LIST_HEAD(&qinf->qi_lru_list);
+       qinf->qi_lru_count = 0;
+       mutex_init(&qinf->qi_lru_lock);
+
        qinf->qi_dqreclaims = 0;
 
        /* mutex used to serialize quotaoffs */
@@ -893,6 +877,9 @@ xfs_qm_init_quotainfo(
                qinf->qi_rtbwarnlimit = XFS_QM_RTBWARNLIMIT;
        }
 
+       qinf->qi_shrinker.shrink = xfs_qm_shake;
+       qinf->qi_shrinker.seeks = DEFAULT_SEEKS;
+       register_shrinker(&qinf->qi_shrinker);
        return 0;
 }
 
@@ -912,6 +899,8 @@ xfs_qm_destroy_quotainfo(
        ASSERT(qi != NULL);
        ASSERT(xfs_Gqm != NULL);
 
+       unregister_shrinker(&qi->qi_shrinker);
+
        /*
         * Release the reference that XQM kept, so that we know
         * when the XQM structure should be freed. We cannot assume
@@ -1623,6 +1612,7 @@ xfs_qm_dqreclaim_one(
        struct list_head        *dispose_list)
 {
        struct xfs_mount        *mp = dqp->q_mount;
+       struct xfs_quotainfo    *qi = mp->m_quotainfo;
        int                     error;
 
        if (!xfs_dqlock_nowait(dqp))
@@ -1638,8 +1628,8 @@ xfs_qm_dqreclaim_one(
                trace_xfs_dqreclaim_want(dqp);
                XFS_STATS_INC(xs_qm_dqwants);
 
-               list_del_init(&dqp->q_freelist);
-               xfs_Gqm->qm_dqfrlist_cnt--;
+               list_del_init(&dqp->q_lru);
+               qi->qi_lru_count--;
                XFS_STATS_DEC(xs_qm_dquot_unused);
                return;
        }
@@ -1688,8 +1678,8 @@ xfs_qm_dqreclaim_one(
        xfs_dqunlock(dqp);
 
        ASSERT(dqp->q_nrefs == 0);
-       list_move_tail(&dqp->q_freelist, dispose_list);
-       xfs_Gqm->qm_dqfrlist_cnt--;
+       list_move_tail(&dqp->q_lru, dispose_list);
+       qi->qi_lru_count--;
        XFS_STATS_DEC(xs_qm_dquot_unused);
 
        trace_xfs_dqreclaim_done(dqp);
@@ -1702,7 +1692,7 @@ out_busy:
        /*
         * Move the dquot to the tail of the list so that we don't spin on it.
         */
-       list_move_tail(&dqp->q_freelist, &xfs_Gqm->qm_dqfrlist);
+       list_move_tail(&dqp->q_lru, &qi->qi_lru_list);
 
        trace_xfs_dqreclaim_busy(dqp);
        XFS_STATS_INC(xs_qm_dqreclaim_misses);
@@ -1713,6 +1703,8 @@ xfs_qm_shake(
        struct shrinker         *shrink,
        struct shrink_control   *sc)
 {
+       struct xfs_quotainfo    *qi =
+               container_of(shrink, struct xfs_quotainfo, qi_shrinker);
        int                     nr_to_scan = sc->nr_to_scan;
        LIST_HEAD               (dispose_list);
        struct xfs_dquot        *dqp;
@@ -1722,24 +1714,23 @@ xfs_qm_shake(
        if (!nr_to_scan)
                goto out;
 
-       mutex_lock(&xfs_Gqm->qm_dqfrlist_lock);
-       while (!list_empty(&xfs_Gqm->qm_dqfrlist)) {
+       mutex_lock(&qi->qi_lru_lock);
+       while (!list_empty(&qi->qi_lru_list)) {
                if (nr_to_scan-- <= 0)
                        break;
-               dqp = list_first_entry(&xfs_Gqm->qm_dqfrlist, struct xfs_dquot,
-                                      q_freelist);
+               dqp = list_first_entry(&qi->qi_lru_list, struct xfs_dquot,
+                                      q_lru);
                xfs_qm_dqreclaim_one(dqp, &dispose_list);
        }
-       mutex_unlock(&xfs_Gqm->qm_dqfrlist_lock);
+       mutex_unlock(&qi->qi_lru_lock);
 
        while (!list_empty(&dispose_list)) {
-               dqp = list_first_entry(&dispose_list, struct xfs_dquot,
-                                      q_freelist);
-               list_del_init(&dqp->q_freelist);
+               dqp = list_first_entry(&dispose_list, struct xfs_dquot, q_lru);
+               list_del_init(&dqp->q_lru);
                xfs_qm_dqfree_one(dqp);
        }
 out:
-       return (xfs_Gqm->qm_dqfrlist_cnt / 100) * sysctl_vfs_cache_pressure;
+       return (qi->qi_lru_count / 100) * sysctl_vfs_cache_pressure;
 }
 
 /*
Index: xfs/fs/xfs/xfs_qm.h
===================================================================
--- xfs.orig/fs/xfs/xfs_qm.h    2012-02-17 19:10:49.000000000 -0800
+++ xfs/fs/xfs/xfs_qm.h 2012-02-17 19:14:06.713328536 -0800
@@ -56,9 +56,6 @@ typedef struct xfs_qm {
        xfs_dqlist_t    *qm_usr_dqhtable;/* udquot hash table */
        xfs_dqlist_t    *qm_grp_dqhtable;/* gdquot hash table */
        uint             qm_dqhashmask;  /* # buckets in dq hashtab - 1 */
-       struct list_head qm_dqfrlist;    /* freelist of dquots */
-       struct mutex     qm_dqfrlist_lock;
-       int              qm_dqfrlist_cnt;
        uint             qm_nrefs;       /* file systems with quota on */
        kmem_zone_t     *qm_dqzone;      /* dquot mem-alloc zone */
        kmem_zone_t     *qm_dqtrxzone;   /* t_dqinfo of transactions */
@@ -71,6 +68,9 @@ typedef struct xfs_qm {
 typedef struct xfs_quotainfo {
        xfs_inode_t     *qi_uquotaip;    /* user quota inode */
        xfs_inode_t     *qi_gquotaip;    /* group quota inode */
+       struct list_head qi_lru_list;
+       struct mutex     qi_lru_lock;
+       int              qi_lru_count;
        struct list_head qi_dqlist;      /* all dquots in filesys */
        struct mutex     qi_dqlist_lock;
        int              qi_dquots;
@@ -91,6 +91,7 @@ typedef struct xfs_quotainfo {
        xfs_qcnt_t       qi_isoftlimit;  /* default inode count soft limit */
        xfs_qcnt_t       qi_rtbhardlimit;/* default realtime blk hard limit */
        xfs_qcnt_t       qi_rtbsoftlimit;/* default realtime blk soft limit */
+       struct shrinker  qi_shrinker;
 } xfs_quotainfo_t;
 
 

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