xfs: remove the per-filesystem list of dquots

Instead of keeping a separate per-filesystem list of dquots we can walk
the radix tree for the two places where we need to iterate all quota
structures.

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

1 files changed, 219 insertions, 196 deletions

diff --git a/fs/xfs/xfs_qm.c b/fs/xfs/xfs_qm.c
index bb884e701cd9..2f92d3b0d8a8 100644
--- a/fs/xfs/xfs_qm.c
+++ b/fs/xfs/xfs_qm.c
@@ -169,6 +169,187 @@ xfs_qm_rele_quotafs_ref(
 }
 
 /*
+ * We use the batch lookup interface to iterate over the dquots as it
+ * currently is the only interface into the radix tree code that allows
+ * fuzzy lookups instead of exact matches.  Holding the lock over multiple
+ * operations is fine as all callers are used either during mount/umount
+ * or quotaoff.
+ */
+#define XFS_DQ_LOOKUP_BATCH     32
+
+STATIC int
+xfs_qm_dquot_walk(
+        struct xfs_mount        *mp,
+        int                     type,
+        int                     (*execute)(struct xfs_dquot *dqp))
+{
+        struct xfs_quotainfo    *qi = mp->m_quotainfo;
+        struct radix_tree_root  *tree = XFS_DQUOT_TREE(qi, type);
+        uint32_t                next_index;
+        int                     last_error = 0;
+        int                     skipped;
+        int                     nr_found;
+
+restart:
+        skipped = 0;
+        next_index = 0;
+        nr_found = 0;
+
+        while (1) {
+                struct xfs_dquot *batch[XFS_DQ_LOOKUP_BATCH];
+                int             error = 0;
+                int             i;
+
+                mutex_lock(&qi->qi_tree_lock);
+                nr_found = radix_tree_gang_lookup(tree, (void **)batch,
+                                        next_index, XFS_DQ_LOOKUP_BATCH);
+                if (!nr_found) {
+                        mutex_unlock(&qi->qi_tree_lock);
+                        break;
+                }
+
+                for (i = 0; i < nr_found; i++) {
+                        struct xfs_dquot *dqp = batch[i];
+
+                        next_index = be32_to_cpu(dqp->q_core.d_id) + 1;
+
+                        error = execute(batch[i]);
+                        if (error == EAGAIN) {
+                                skipped++;
+                                continue;
+                        }
+                        if (error && last_error != EFSCORRUPTED)
+                                last_error = error;
+                }
+
+                mutex_unlock(&qi->qi_tree_lock);
+
+                /* bail out if the filesystem is corrupted.  */
+                if (last_error == EFSCORRUPTED) {
+                        skipped = 0;
+                        break;
+                }
+        }
+
+        if (skipped) {
+                delay(1);
+                goto restart;
+        }
+
+        return last_error;
+}
+
+
+/*
+ * Purge a dquot from all tracking data structures and free it.
+ */
+STATIC int
+xfs_qm_dqpurge(
+        struct xfs_dquot        *dqp)
+{
+        struct xfs_mount        *mp = dqp->q_mount;
+        struct xfs_quotainfo    *qi = mp->m_quotainfo;
+        struct xfs_dquot        *gdqp = NULL;
+
+        xfs_dqlock(dqp);
+        if ((dqp->dq_flags & XFS_DQ_FREEING) || dqp->q_nrefs != 0) {
+                xfs_dqunlock(dqp);
+                return EAGAIN;
+        }
+
+        /*
+         * If this quota has a group hint attached, prepare for releasing it
+         * now.
+         */
+        gdqp = dqp->q_gdquot;
+        if (gdqp) {
+                xfs_dqlock(gdqp);
+                dqp->q_gdquot = NULL;
+        }
+
+        dqp->dq_flags |= XFS_DQ_FREEING;
+
+        /*
+         * If we're turning off quotas, we have to make sure that, for
+         * example, we don't delete quota disk blocks while dquots are
+         * in the process of getting written to those disk blocks.
+         * This dquot might well be on AIL, and we can't leave it there
+         * if we're turning off quotas. Basically, we need this flush
+         * lock, and are willing to block on it.
+         */
+        if (!xfs_dqflock_nowait(dqp)) {
+                /*
+                 * Block on the flush lock after nudging dquot buffer,
+                 * if it is incore.
+                 */
+                xfs_dqflock_pushbuf_wait(dqp);
+        }
+
+        /*
+         * If we are turning this type of quotas off, we don't care
+         * about the dirty metadata sitting in this dquot. OTOH, if
+         * we're unmounting, we do care, so we flush it and wait.
+         */
+        if (XFS_DQ_IS_DIRTY(dqp)) {
+                int     error;
+
+                /*
+                 * We don't care about getting disk errors here. We need
+                 * to purge this dquot anyway, so we go ahead regardless.
+                 */
+                error = xfs_qm_dqflush(dqp, SYNC_WAIT);
+                if (error)
+                        xfs_warn(mp, "%s: dquot %p flush failed",
+                                __func__, dqp);
+                xfs_dqflock(dqp);
+        }
+
+        ASSERT(atomic_read(&dqp->q_pincount) == 0);
+        ASSERT(XFS_FORCED_SHUTDOWN(mp) ||
+               !(dqp->q_logitem.qli_item.li_flags & XFS_LI_IN_AIL));
+
+        xfs_dqfunlock(dqp);
+        xfs_dqunlock(dqp);
+
+        radix_tree_delete(XFS_DQUOT_TREE(qi, dqp->q_core.d_flags),
+                          be32_to_cpu(dqp->q_core.d_id));
+        qi->qi_dquots--;
+
+        /*
+         * 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(&qi->qi_lru_lock);
+        ASSERT(!list_empty(&dqp->q_lru));
+        list_del_init(&dqp->q_lru);
+        qi->qi_lru_count--;
+        XFS_STATS_DEC(xs_qm_dquot_unused);
+        mutex_unlock(&qi->qi_lru_lock);
+
+        xfs_qm_dqdestroy(dqp);
+
+        if (gdqp)
+                xfs_qm_dqput(gdqp);
+        return 0;
+}
+
+/*
+ * Purge the dquot cache.
+ */
+void
+xfs_qm_dqpurge_all(
+        struct xfs_mount        *mp,
+        uint                    flags)
+{
+        if (flags & XFS_QMOPT_UQUOTA)
+                xfs_qm_dquot_walk(mp, XFS_DQ_USER, xfs_qm_dqpurge);
+        if (flags & XFS_QMOPT_GQUOTA)
+                xfs_qm_dquot_walk(mp, XFS_DQ_GROUP, xfs_qm_dqpurge);
+        if (flags & XFS_QMOPT_PQUOTA)
+                xfs_qm_dquot_walk(mp, XFS_DQ_PROJ, xfs_qm_dqpurge);
+}
+
+/*
  * Just destroy the quotainfo structure.
  */
 void
@@ -306,175 +487,6 @@ xfs_qm_unmount_quotas(
         }
 }
 
-/*
- * Flush all dquots of the given file system to disk. The dquots are
- * _not_ purged from memory here, just their data written to disk.
- */
-STATIC int
-xfs_qm_dqflush_all(
-        struct xfs_mount        *mp)
-{
-        struct xfs_quotainfo    *q = mp->m_quotainfo;
-        int                     recl;
-        struct xfs_dquot        *dqp;
-        int                     error;
-
-        if (!q)
-                return 0;
-again:
-        mutex_lock(&q->qi_dqlist_lock);
-        list_for_each_entry(dqp, &q->qi_dqlist, q_mplist) {
-                xfs_dqlock(dqp);
-                if ((dqp->dq_flags & XFS_DQ_FREEING) ||
-                    !XFS_DQ_IS_DIRTY(dqp)) {
-                        xfs_dqunlock(dqp);
-                        continue;
-                }
-
-                /* XXX a sentinel would be better */
-                recl = q->qi_dqreclaims;
-                if (!xfs_dqflock_nowait(dqp)) {
-                        /*
-                         * If we can't grab the flush lock then check
-                         * to see if the dquot has been flushed delayed
-                         * write.  If so, grab its buffer and send it
-                         * out immediately.  We'll be able to acquire
-                         * the flush lock when the I/O completes.
-                         */
-                        xfs_dqflock_pushbuf_wait(dqp);
-                }
-                /*
-                 * Let go of the mplist lock. We don't want to hold it
-                 * across a disk write.
-                 */
-                mutex_unlock(&q->qi_dqlist_lock);
-                error = xfs_qm_dqflush(dqp, 0);
-                xfs_dqunlock(dqp);
-                if (error)
-                        return error;
-
-                mutex_lock(&q->qi_dqlist_lock);
-                if (recl != q->qi_dqreclaims) {
-                        mutex_unlock(&q->qi_dqlist_lock);
-                        /* XXX restart limit */
-                        goto again;
-                }
-        }
-
-        mutex_unlock(&q->qi_dqlist_lock);
-        /* return ! busy */
-        return 0;
-}
-
-/*
- * Release the group dquot pointers the user dquots may be
- * carrying around as a hint. mplist is locked on entry and exit.
- */
-STATIC void
-xfs_qm_detach_gdquots(
-        struct xfs_mount        *mp)
-{
-        struct xfs_quotainfo    *q = mp->m_quotainfo;
-        struct xfs_dquot        *dqp, *gdqp;
-
- again:
-        ASSERT(mutex_is_locked(&q->qi_dqlist_lock));
-        list_for_each_entry(dqp, &q->qi_dqlist, q_mplist) {
-                xfs_dqlock(dqp);
-                if (dqp->dq_flags & XFS_DQ_FREEING) {
-                        xfs_dqunlock(dqp);
-                        mutex_unlock(&q->qi_dqlist_lock);
-                        delay(1);
-                        mutex_lock(&q->qi_dqlist_lock);
-                        goto again;
-                }
-
-                gdqp = dqp->q_gdquot;
-                if (gdqp)
-                        dqp->q_gdquot = NULL;
-                xfs_dqunlock(dqp);
-
-                if (gdqp)
-                        xfs_qm_dqrele(gdqp);
-        }
-}
-
-/*
- * Go through all the incore dquots of this file system and take them
- * off the mplist and hashlist, if the dquot type matches the dqtype
- * parameter. This is used when turning off quota accounting for
- * users and/or groups, as well as when the filesystem is unmounting.
- */
-STATIC int
-xfs_qm_dqpurge_int(
-        struct xfs_mount        *mp,
-        uint                    flags)
-{
-        struct xfs_quotainfo    *q = mp->m_quotainfo;
-        struct xfs_dquot        *dqp, *n;
-        uint                    dqtype;
-        int                     nmisses = 0;
-        LIST_HEAD               (dispose_list);
-
-        if (!q)
-                return 0;
-
-        dqtype = (flags & XFS_QMOPT_UQUOTA) ? XFS_DQ_USER : 0;
-        dqtype |= (flags & XFS_QMOPT_PQUOTA) ? XFS_DQ_PROJ : 0;
-        dqtype |= (flags & XFS_QMOPT_GQUOTA) ? XFS_DQ_GROUP : 0;
-
-        mutex_lock(&q->qi_dqlist_lock);
-
-        /*
-         * In the first pass through all incore dquots of this filesystem,
-         * we release the group dquot pointers the user dquots may be
-         * carrying around as a hint. We need to do this irrespective of
-         * what's being turned off.
-         */
-        xfs_qm_detach_gdquots(mp);
-
-        /*
-         * Try to get rid of all of the unwanted dquots.
-         */
-        list_for_each_entry_safe(dqp, n, &q->qi_dqlist, q_mplist) {
-                xfs_dqlock(dqp);
-                if ((dqp->dq_flags & dqtype) != 0 &&
-                    !(dqp->dq_flags & XFS_DQ_FREEING)) {
-                        if (dqp->q_nrefs == 0) {
-                                dqp->dq_flags |= XFS_DQ_FREEING;
-                                list_move_tail(&dqp->q_mplist, &dispose_list);
-                        } else
-                                nmisses++;
-                }
-                xfs_dqunlock(dqp);
-        }
-        mutex_unlock(&q->qi_dqlist_lock);
-
-        list_for_each_entry_safe(dqp, n, &dispose_list, q_mplist)
-                xfs_qm_dqpurge(dqp);
-
-        return nmisses;
-}
-
-int
-xfs_qm_dqpurge_all(
-        xfs_mount_t     *mp,
-        uint            flags)
-{
-        int             ndquots;
-
-        /*
-         * Purge the dquot cache.
-         * None of the dquots should really be busy at this point.
-         */
-        if (mp->m_quotainfo) {
-                while ((ndquots = xfs_qm_dqpurge_int(mp, flags))) {
-                        delay(ndquots * 10);
-                }
-        }
-        return 0;
-}
-
 STATIC int
 xfs_qm_dqattach_one(
         xfs_inode_t     *ip,
@@ -749,15 +761,10 @@ xfs_qm_init_quotainfo(
         INIT_RADIX_TREE(&qinf->qi_gquota_tree, GFP_NOFS);
         mutex_init(&qinf->qi_tree_lock);
 
-        INIT_LIST_HEAD(&qinf->qi_dqlist);
-        mutex_init(&qinf->qi_dqlist_lock);
-
         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 */
         mutex_init(&qinf->qi_quotaofflock);
 
@@ -854,9 +861,6 @@ xfs_qm_destroy_quotainfo(
          */
         xfs_qm_rele_quotafs_ref(mp);
 
-        ASSERT(list_empty(&qi->qi_dqlist));
-        mutex_destroy(&qi->qi_dqlist_lock);
-
         if (qi->qi_uquotaip) {
                 IRELE(qi->qi_uquotaip);
                 qi->qi_uquotaip = NULL; /* paranoia */
@@ -1307,6 +1311,28 @@ error0:
         return error;
 }
 
+STATIC int
+xfs_qm_flush_one(
+        struct xfs_dquot        *dqp)
+{
+        int                     error = 0;
+
+        xfs_dqlock(dqp);
+        if (dqp->dq_flags & XFS_DQ_FREEING)
+                goto out_unlock;
+        if (!XFS_DQ_IS_DIRTY(dqp))
+                goto out_unlock;
+
+        if (!xfs_dqflock_nowait(dqp))
+                xfs_dqflock_pushbuf_wait(dqp);
+
+        error = xfs_qm_dqflush(dqp, 0);
+
+out_unlock:
+        xfs_dqunlock(dqp);
+        return error;
+}
+
 /*
  * Walk thru all the filesystem inodes and construct a consistent view
  * of the disk quota world. If the quotacheck fails, disable quotas.
@@ -1315,7 +1341,7 @@ int
 xfs_qm_quotacheck(
         xfs_mount_t     *mp)
 {
-        int             done, count, error;
+        int             done, count, error, error2;
         xfs_ino_t       lastino;
         size_t          structsz;
         xfs_inode_t     *uip, *gip;
@@ -1329,12 +1355,6 @@ xfs_qm_quotacheck(
         ASSERT(mp->m_quotainfo->qi_uquotaip || mp->m_quotainfo->qi_gquotaip);
         ASSERT(XFS_IS_QUOTA_RUNNING(mp));
 
-        /*
-         * There should be no cached dquots. The (simplistic) quotacheck
-         * algorithm doesn't like that.
-         */
-        ASSERT(list_empty(&mp->m_quotainfo->qi_dqlist));
-
         xfs_notice(mp, "Quotacheck needed: Please wait.");
 
         /*
@@ -1373,12 +1393,21 @@ xfs_qm_quotacheck(
         } while (!done);
 
         /*
-         * We've made all the changes that we need to make incore.
-         * Flush them down to disk buffers if everything was updated
-         * successfully.
+         * We've made all the changes that we need to make incore.  Flush them
+         * down to disk buffers if everything was updated successfully.
          */
-        if (!error)
-                error = xfs_qm_dqflush_all(mp);
+        if (XFS_IS_UQUOTA_ON(mp))
+                error = xfs_qm_dquot_walk(mp, XFS_DQ_USER, xfs_qm_flush_one);
+        if (XFS_IS_GQUOTA_ON(mp)) {
+                error2 = xfs_qm_dquot_walk(mp, XFS_DQ_GROUP, xfs_qm_flush_one);
+                if (!error)
+                        error = error2;
+        }
+        if (XFS_IS_PQUOTA_ON(mp)) {
+                error2 = xfs_qm_dquot_walk(mp, XFS_DQ_PROJ, xfs_qm_flush_one);
+                if (!error)
+                        error = error2;
+        }
 
         /*
          * We can get this error if we couldn't do a dquot allocation inside
@@ -1517,13 +1546,9 @@ xfs_qm_dqfree_one(
         mutex_lock(&qi->qi_tree_lock);
         radix_tree_delete(XFS_DQUOT_TREE(qi, dqp->q_core.d_flags),
                           be32_to_cpu(dqp->q_core.d_id));
-        mutex_unlock(&qi->qi_tree_lock);
 
-        mutex_lock(&qi->qi_dqlist_lock);
-        list_del_init(&dqp->q_mplist);
         qi->qi_dquots--;
-        qi->qi_dqreclaims++;
-        mutex_unlock(&qi->qi_dqlist_lock);
+        mutex_unlock(&qi->qi_tree_lock);
 
         xfs_qm_dqdestroy(dqp);
 }
@@ -1556,8 +1581,6 @@ xfs_qm_dqreclaim_one(
                 return;
         }
 
-        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.