1 files changed, 108 insertions, 810 deletions

diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 4fa80e63eea2..2ce7ee3b4ec1 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -43,18 +43,6 @@
 #include "xfs_sysfs.h"
 
 
-#ifdef HAVE_PERCPU_SB
-STATIC void     xfs_icsb_balance_counter(xfs_mount_t *, xfs_sb_field_t,
-                                                int);
-STATIC void     xfs_icsb_balance_counter_locked(xfs_mount_t *, xfs_sb_field_t,
-                                                int);
-STATIC void     xfs_icsb_disable_counter(xfs_mount_t *, xfs_sb_field_t);
-#else
-
-#define xfs_icsb_balance_counter(mp, a, b)              do { } while (0)
-#define xfs_icsb_balance_counter_locked(mp, a, b)       do { } while (0)
-#endif
-
 static DEFINE_MUTEX(xfs_uuid_table_mutex);
 static int xfs_uuid_table_size;
 static uuid_t *xfs_uuid_table;
@@ -347,8 +335,7 @@ reread:
                 goto reread;
         }
 
-        /* Initialize per-cpu counters */
-        xfs_icsb_reinit_counters(mp);
+        xfs_reinit_percpu_counters(mp);
 
         /* no need to be quiet anymore, so reset the buf ops */
         bp->b_ops = &xfs_sb_buf_ops;
@@ -1087,8 +1074,6 @@ xfs_log_sbcount(xfs_mount_t *mp)
         if (!xfs_fs_writable(mp, SB_FREEZE_COMPLETE))
                 return 0;
 
-        xfs_icsb_sync_counters(mp, 0);
-
         /*
          * we don't need to do this if we are updating the superblock
          * counters on every modification.
@@ -1099,253 +1084,136 @@ xfs_log_sbcount(xfs_mount_t *mp)
         return xfs_sync_sb(mp, true);
 }
 
-/*
- * xfs_mod_incore_sb_unlocked() is a utility routine commonly used to apply
- * a delta to a specified field in the in-core superblock.  Simply
- * switch on the field indicated and apply the delta to that field.
- * Fields are not allowed to dip below zero, so if the delta would
- * do this do not apply it and return EINVAL.
- *
- * The m_sb_lock must be held when this routine is called.
- */
-STATIC int
-xfs_mod_incore_sb_unlocked(
-        xfs_mount_t     *mp,
-        xfs_sb_field_t  field,
-        int64_t         delta,
-        int             rsvd)
+int
+xfs_mod_icount(
+        struct xfs_mount        *mp,
+        int64_t                 delta)
 {
-        int             scounter;       /* short counter for 32 bit fields */
-        long long       lcounter;       /* long counter for 64 bit fields */
-        long long       res_used, rem;
-
-        /*
-         * With the in-core superblock spin lock held, switch
-         * on the indicated field.  Apply the delta to the
-         * proper field.  If the fields value would dip below
-         * 0, then do not apply the delta and return EINVAL.
-         */
-        switch (field) {
-        case XFS_SBS_ICOUNT:
-                lcounter = (long long)mp->m_sb.sb_icount;
-                lcounter += delta;
-                if (lcounter < 0) {
-                        ASSERT(0);
-                        return -EINVAL;
-                }
-                mp->m_sb.sb_icount = lcounter;
-                return 0;
-        case XFS_SBS_IFREE:
-                lcounter = (long long)mp->m_sb.sb_ifree;
-                lcounter += delta;
-                if (lcounter < 0) {
-                        ASSERT(0);
-                        return -EINVAL;
-                }
-                mp->m_sb.sb_ifree = lcounter;
-                return 0;
-        case XFS_SBS_FDBLOCKS:
-                lcounter = (long long)
-                        mp->m_sb.sb_fdblocks - XFS_ALLOC_SET_ASIDE(mp);
-                res_used = (long long)(mp->m_resblks - mp->m_resblks_avail);
-
-                if (delta > 0) {                /* Putting blocks back */
-                        if (res_used > delta) {
-                                mp->m_resblks_avail += delta;
-                        } else {
-                                rem = delta - res_used;
-                                mp->m_resblks_avail = mp->m_resblks;
-                                lcounter += rem;
-                        }
-                } else {                                /* Taking blocks away */
-                        lcounter += delta;
-                        if (lcounter >= 0) {
-                                mp->m_sb.sb_fdblocks = lcounter +
-                                                        XFS_ALLOC_SET_ASIDE(mp);
-                                return 0;
-                        }
-
-                        /*
-                         * We are out of blocks, use any available reserved
-                         * blocks if were allowed to.
-                         */
-                        if (!rsvd)
-                                return -ENOSPC;
-
-                        lcounter = (long long)mp->m_resblks_avail + delta;
-                        if (lcounter >= 0) {
-                                mp->m_resblks_avail = lcounter;
-                                return 0;
-                        }
-                        printk_once(KERN_WARNING
-                                "Filesystem \"%s\": reserve blocks depleted! "
-                                "Consider increasing reserve pool size.",
-                                mp->m_fsname);
-                        return -ENOSPC;
-                }
-
-                mp->m_sb.sb_fdblocks = lcounter + XFS_ALLOC_SET_ASIDE(mp);
-                return 0;
-        case XFS_SBS_FREXTENTS:
-                lcounter = (long long)mp->m_sb.sb_frextents;
-                lcounter += delta;
-                if (lcounter < 0) {
-                        return -ENOSPC;
-                }
-                mp->m_sb.sb_frextents = lcounter;
-                return 0;
-        case XFS_SBS_DBLOCKS:
-                lcounter = (long long)mp->m_sb.sb_dblocks;
-                lcounter += delta;
-                if (lcounter < 0) {
-                        ASSERT(0);
-                        return -EINVAL;
-                }
-                mp->m_sb.sb_dblocks = lcounter;
-                return 0;
-        case XFS_SBS_AGCOUNT:
-                scounter = mp->m_sb.sb_agcount;
-                scounter += delta;
-                if (scounter < 0) {
-                        ASSERT(0);
-                        return -EINVAL;
-                }
-                mp->m_sb.sb_agcount = scounter;
-                return 0;
-        case XFS_SBS_IMAX_PCT:
-                scounter = mp->m_sb.sb_imax_pct;
-                scounter += delta;
-                if (scounter < 0) {
-                        ASSERT(0);
-                        return -EINVAL;
-                }
-                mp->m_sb.sb_imax_pct = scounter;
-                return 0;
-        case XFS_SBS_REXTSIZE:
-                scounter = mp->m_sb.sb_rextsize;
-                scounter += delta;
-                if (scounter < 0) {
-                        ASSERT(0);
-                        return -EINVAL;
-                }
-                mp->m_sb.sb_rextsize = scounter;
-                return 0;
-        case XFS_SBS_RBMBLOCKS:
-                scounter = mp->m_sb.sb_rbmblocks;
-                scounter += delta;
-                if (scounter < 0) {
-                        ASSERT(0);
-                        return -EINVAL;
-                }
-                mp->m_sb.sb_rbmblocks = scounter;
-                return 0;
-        case XFS_SBS_RBLOCKS:
-                lcounter = (long long)mp->m_sb.sb_rblocks;
-                lcounter += delta;
-                if (lcounter < 0) {
-                        ASSERT(0);
-                        return -EINVAL;
-                }
-                mp->m_sb.sb_rblocks = lcounter;
-                return 0;
-        case XFS_SBS_REXTENTS:
-                lcounter = (long long)mp->m_sb.sb_rextents;
-                lcounter += delta;
-                if (lcounter < 0) {
-                        ASSERT(0);
-                        return -EINVAL;
-                }
-                mp->m_sb.sb_rextents = lcounter;
-                return 0;
-        case XFS_SBS_REXTSLOG:
-                scounter = mp->m_sb.sb_rextslog;
-                scounter += delta;
-                if (scounter < 0) {
-                        ASSERT(0);
-                        return -EINVAL;
-                }
-                mp->m_sb.sb_rextslog = scounter;
-                return 0;
-        default:
+        /* deltas are +/-64, hence the large batch size of 128. */
+        __percpu_counter_add(&mp->m_icount, delta, 128);
+        if (percpu_counter_compare(&mp->m_icount, 0) < 0) {
                 ASSERT(0);
+                percpu_counter_add(&mp->m_icount, -delta);
                 return -EINVAL;
         }
+        return 0;
 }
 
-/*
- * xfs_mod_incore_sb() is used to change a field in the in-core
- * superblock structure by the specified delta.  This modification
- * is protected by the m_sb_lock.  Just use the xfs_mod_incore_sb_unlocked()
- * routine to do the work.
- */
 int
-xfs_mod_incore_sb(
+xfs_mod_ifree(
         struct xfs_mount        *mp,
-        xfs_sb_field_t          field,
-        int64_t                 delta,
-        int                     rsvd)
+        int64_t                 delta)
 {
-        int                     status;
-
-#ifdef HAVE_PERCPU_SB
-        ASSERT(field < XFS_SBS_ICOUNT || field > XFS_SBS_FDBLOCKS);
-#endif
-        spin_lock(&mp->m_sb_lock);
-        status = xfs_mod_incore_sb_unlocked(mp, field, delta, rsvd);
-        spin_unlock(&mp->m_sb_lock);
-
-        return status;
+        percpu_counter_add(&mp->m_ifree, delta);
+        if (percpu_counter_compare(&mp->m_ifree, 0) < 0) {
+                ASSERT(0);
+                percpu_counter_add(&mp->m_ifree, -delta);
+                return -EINVAL;
+        }
+        return 0;
 }
 
-/*
- * Change more than one field in the in-core superblock structure at a time.
- *
- * The fields and changes to those fields are specified in the array of
- * xfs_mod_sb structures passed in.  Either all of the specified deltas
- * will be applied or none of them will.  If any modified field dips below 0,
- * then all modifications will be backed out and EINVAL will be returned.
- *
- * Note that this function may not be used for the superblock values that
- * are tracked with the in-memory per-cpu counters - a direct call to
- * xfs_icsb_modify_counters is required for these.
- */
 int
-xfs_mod_incore_sb_batch(
+xfs_mod_fdblocks(
         struct xfs_mount        *mp,
-        xfs_mod_sb_t            *msb,
-        uint                    nmsb,
-        int                     rsvd)
+        int64_t                 delta,
+        bool                    rsvd)
 {
-        xfs_mod_sb_t            *msbp;
-        int                     error = 0;
+        int64_t                 lcounter;
+        long long               res_used;
+        s32                     batch;
+
+        if (delta > 0) {
+                /*
+                 * If the reserve pool is depleted, put blocks back into it
+                 * first. Most of the time the pool is full.
+                 */
+                if (likely(mp->m_resblks == mp->m_resblks_avail)) {
+                        percpu_counter_add(&mp->m_fdblocks, delta);
+                        return 0;
+                }
+
+                spin_lock(&mp->m_sb_lock);
+                res_used = (long long)(mp->m_resblks - mp->m_resblks_avail);
+
+                if (res_used > delta) {
+                        mp->m_resblks_avail += delta;
+                } else {
+                        delta -= res_used;
+                        mp->m_resblks_avail = mp->m_resblks;
+                        percpu_counter_add(&mp->m_fdblocks, delta);
+                }
+                spin_unlock(&mp->m_sb_lock);
+                return 0;
+        }
 
         /*
-         * Loop through the array of mod structures and apply each individually.
-         * If any fail, then back out all those which have already been applied.
-         * Do all of this within the scope of the m_sb_lock so that all of the
-         * changes will be atomic.
+         * Taking blocks away, need to be more accurate the closer we
+         * are to zero.
+         *
+         * batch size is set to a maximum of 1024 blocks - if we are
+         * allocating of freeing extents larger than this then we aren't
+         * going to be hammering the counter lock so a lock per update
+         * is not a problem.
+         *
+         * If the counter has a value of less than 2 * max batch size,
+         * then make everything serialise as we are real close to
+         * ENOSPC.
+         */
+#define __BATCH 1024
+        if (percpu_counter_compare(&mp->m_fdblocks, 2 * __BATCH) < 0)
+                batch = 1;
+        else
+                batch = __BATCH;
+#undef __BATCH
+
+        __percpu_counter_add(&mp->m_fdblocks, delta, batch);
+        if (percpu_counter_compare(&mp->m_fdblocks,
+                                   XFS_ALLOC_SET_ASIDE(mp)) >= 0) {
+                /* we had space! */
+                return 0;
+        }
+
+        /*
+         * lock up the sb for dipping into reserves before releasing the space
+         * that took us to ENOSPC.
          */
         spin_lock(&mp->m_sb_lock);
-        for (msbp = msb; msbp < (msb + nmsb); msbp++) {
-                ASSERT(msbp->msb_field < XFS_SBS_ICOUNT ||
-                       msbp->msb_field > XFS_SBS_FDBLOCKS);
+        percpu_counter_add(&mp->m_fdblocks, -delta);
+        if (!rsvd)
+                goto fdblocks_enospc;
 
-                error = xfs_mod_incore_sb_unlocked(mp, msbp->msb_field,
-                                                   msbp->msb_delta, rsvd);
-                if (error)
-                        goto unwind;
+        lcounter = (long long)mp->m_resblks_avail + delta;
+        if (lcounter >= 0) {
+                mp->m_resblks_avail = lcounter;
+                spin_unlock(&mp->m_sb_lock);
+                return 0;
         }
+        printk_once(KERN_WARNING
+                "Filesystem \"%s\": reserve blocks depleted! "
+                "Consider increasing reserve pool size.",
+                mp->m_fsname);
+fdblocks_enospc:
         spin_unlock(&mp->m_sb_lock);
-        return 0;
+        return -ENOSPC;
+}
 
-unwind:
-        while (--msbp >= msb) {
-                error = xfs_mod_incore_sb_unlocked(mp, msbp->msb_field,
-                                                   -msbp->msb_delta, rsvd);
-                ASSERT(error == 0);
-        }
+int
+xfs_mod_frextents(
+        struct xfs_mount        *mp,
+        int64_t                 delta)
+{
+        int64_t                 lcounter;
+        int                     ret = 0;
+
+        spin_lock(&mp->m_sb_lock);
+        lcounter = mp->m_sb.sb_frextents + delta;
+        if (lcounter < 0)
+                ret = -ENOSPC;
+        else
+                mp->m_sb.sb_frextents = lcounter;
         spin_unlock(&mp->m_sb_lock);
-        return error;
+        return ret;
 }
 
 /*
@@ -1407,573 +1275,3 @@ xfs_dev_is_read_only(
         }
         return 0;
 }
-
-#ifdef HAVE_PERCPU_SB
-/*
- * Per-cpu incore superblock counters
- *
- * Simple concept, difficult implementation
- *
- * Basically, replace the incore superblock counters with a distributed per cpu
- * counter for contended fields (e.g.  free block count).
- *
- * Difficulties arise in that the incore sb is used for ENOSPC checking, and
- * hence needs to be accurately read when we are running low on space. Hence
- * there is a method to enable and disable the per-cpu counters based on how
- * much "stuff" is available in them.
- *
- * Basically, a counter is enabled if there is enough free resource to justify
- * running a per-cpu fast-path. If the per-cpu counter runs out (i.e. a local
- * ENOSPC), then we disable the counters to synchronise all callers and
- * re-distribute the available resources.
- *
- * If, once we redistributed the available resources, we still get a failure,
- * we disable the per-cpu counter and go through the slow path.
- *
- * The slow path is the current xfs_mod_incore_sb() function.  This means that
- * when we disable a per-cpu counter, we need to drain its resources back to
- * the global superblock. We do this after disabling the counter to prevent
- * more threads from queueing up on the counter.
- *
- * Essentially, this means that we still need a lock in the fast path to enable
- * synchronisation between the global counters and the per-cpu counters. This
- * is not a problem because the lock will be local to a CPU almost all the time
- * and have little contention except when we get to ENOSPC conditions.
- *
- * Basically, this lock becomes a barrier that enables us to lock out the fast
- * path while we do things like enabling and disabling counters and
- * synchronising the counters.
- *
- * Locking rules:
- *
- *      1. m_sb_lock before picking up per-cpu locks
- *      2. per-cpu locks always picked up via for_each_online_cpu() order
- *      3. accurate counter sync requires m_sb_lock + per cpu locks
- *      4. modifying per-cpu counters requires holding per-cpu lock
- *      5. modifying global counters requires holding m_sb_lock
- *      6. enabling or disabling a counter requires holding the m_sb_lock 
- *         and _none_ of the per-cpu locks.
- *
- * Disabled counters are only ever re-enabled by a balance operation
- * that results in more free resources per CPU than a given threshold.
- * To ensure counters don't remain disabled, they are rebalanced when
- * the global resource goes above a higher threshold (i.e. some hysteresis
- * is present to prevent thrashing).
- */
-
-#ifdef CONFIG_HOTPLUG_CPU
-/*
- * hot-plug CPU notifier support.
- *
- * We need a notifier per filesystem as we need to be able to identify
- * the filesystem to balance the counters out. This is achieved by
- * having a notifier block embedded in the xfs_mount_t and doing pointer
- * magic to get the mount pointer from the notifier block address.
- */
-STATIC int
-xfs_icsb_cpu_notify(
-        struct notifier_block *nfb,
-        unsigned long action,
-        void *hcpu)
-{
-        xfs_icsb_cnts_t *cntp;
-        xfs_mount_t     *mp;
-
-        mp = (xfs_mount_t *)container_of(nfb, xfs_mount_t, m_icsb_notifier);
-        cntp = (xfs_icsb_cnts_t *)
-                        per_cpu_ptr(mp->m_sb_cnts, (unsigned long)hcpu);
-        switch (action) {
-        case CPU_UP_PREPARE:
-        case CPU_UP_PREPARE_FROZEN:
-                /* Easy Case - initialize the area and locks, and
-                 * then rebalance when online does everything else for us. */
-                memset(cntp, 0, sizeof(xfs_icsb_cnts_t));
-                break;
-        case CPU_ONLINE:
-        case CPU_ONLINE_FROZEN:
-                xfs_icsb_lock(mp);
-                xfs_icsb_balance_counter(mp, XFS_SBS_ICOUNT, 0);
-                xfs_icsb_balance_counter(mp, XFS_SBS_IFREE, 0);
-                xfs_icsb_balance_counter(mp, XFS_SBS_FDBLOCKS, 0);
-                xfs_icsb_unlock(mp);
-                break;
-        case CPU_DEAD:
-        case CPU_DEAD_FROZEN:
-                /* Disable all the counters, then fold the dead cpu's
-                 * count into the total on the global superblock and
-                 * re-enable the counters. */
-                xfs_icsb_lock(mp);
-                spin_lock(&mp->m_sb_lock);
-                xfs_icsb_disable_counter(mp, XFS_SBS_ICOUNT);
-                xfs_icsb_disable_counter(mp, XFS_SBS_IFREE);
-                xfs_icsb_disable_counter(mp, XFS_SBS_FDBLOCKS);
-
-                mp->m_sb.sb_icount += cntp->icsb_icount;
-                mp->m_sb.sb_ifree += cntp->icsb_ifree;
-                mp->m_sb.sb_fdblocks += cntp->icsb_fdblocks;
-
-                memset(cntp, 0, sizeof(xfs_icsb_cnts_t));
-
-                xfs_icsb_balance_counter_locked(mp, XFS_SBS_ICOUNT, 0);
-                xfs_icsb_balance_counter_locked(mp, XFS_SBS_IFREE, 0);
-                xfs_icsb_balance_counter_locked(mp, XFS_SBS_FDBLOCKS, 0);
-                spin_unlock(&mp->m_sb_lock);
-                xfs_icsb_unlock(mp);
-                break;
-        }
-
-        return NOTIFY_OK;
-}
-#endif /* CONFIG_HOTPLUG_CPU */
-
-int
-xfs_icsb_init_counters(
-        xfs_mount_t     *mp)
-{
-        xfs_icsb_cnts_t *cntp;
-        int             i;
-
-        mp->m_sb_cnts = alloc_percpu(xfs_icsb_cnts_t);
-        if (mp->m_sb_cnts == NULL)
-                return -ENOMEM;
-
-        for_each_online_cpu(i) {
-                cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i);
-                memset(cntp, 0, sizeof(xfs_icsb_cnts_t));
-        }
-
-        mutex_init(&mp->m_icsb_mutex);
-
-        /*
-         * start with all counters disabled so that the
-         * initial balance kicks us off correctly
-         */
-        mp->m_icsb_counters = -1;
-
-#ifdef CONFIG_HOTPLUG_CPU
-        mp->m_icsb_notifier.notifier_call = xfs_icsb_cpu_notify;
-        mp->m_icsb_notifier.priority = 0;
-        register_hotcpu_notifier(&mp->m_icsb_notifier);
-#endif /* CONFIG_HOTPLUG_CPU */
-
-        return 0;
-}
-
-void
-xfs_icsb_reinit_counters(
-        xfs_mount_t     *mp)
-{
-        xfs_icsb_lock(mp);
-        /*
-         * start with all counters disabled so that the
-         * initial balance kicks us off correctly
-         */
-        mp->m_icsb_counters = -1;
-        xfs_icsb_balance_counter(mp, XFS_SBS_ICOUNT, 0);
-        xfs_icsb_balance_counter(mp, XFS_SBS_IFREE, 0);
-        xfs_icsb_balance_counter(mp, XFS_SBS_FDBLOCKS, 0);
-        xfs_icsb_unlock(mp);
-}
-
-void
-xfs_icsb_destroy_counters(
-        xfs_mount_t     *mp)
-{
-        if (mp->m_sb_cnts) {
-                unregister_hotcpu_notifier(&mp->m_icsb_notifier);
-                free_percpu(mp->m_sb_cnts);
-        }
-        mutex_destroy(&mp->m_icsb_mutex);
-}
-
-STATIC void
-xfs_icsb_lock_cntr(
-        xfs_icsb_cnts_t *icsbp)
-{
-        while (test_and_set_bit(XFS_ICSB_FLAG_LOCK, &icsbp->icsb_flags)) {
-                ndelay(1000);
-        }
-}
-
-STATIC void
-xfs_icsb_unlock_cntr(
-        xfs_icsb_cnts_t *icsbp)
-{
-        clear_bit(XFS_ICSB_FLAG_LOCK, &icsbp->icsb_flags);
-}
-
-
-STATIC void
-xfs_icsb_lock_all_counters(
-        xfs_mount_t     *mp)
-{
-        xfs_icsb_cnts_t *cntp;
-        int             i;
-
-        for_each_online_cpu(i) {
-                cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i);
-                xfs_icsb_lock_cntr(cntp);
-        }
-}
-
-STATIC void
-xfs_icsb_unlock_all_counters(
-        xfs_mount_t     *mp)
-{
-        xfs_icsb_cnts_t *cntp;
-        int             i;
-
-        for_each_online_cpu(i) {
-                cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i);
-                xfs_icsb_unlock_cntr(cntp);
-        }
-}
-
-STATIC void
-xfs_icsb_count(
-        xfs_mount_t     *mp,
-        xfs_icsb_cnts_t *cnt,
-        int             flags)
-{
-        xfs_icsb_cnts_t *cntp;
-        int             i;
-
-        memset(cnt, 0, sizeof(xfs_icsb_cnts_t));
-
-        if (!(flags & XFS_ICSB_LAZY_COUNT))
-                xfs_icsb_lock_all_counters(mp);
-
-        for_each_online_cpu(i) {
-                cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i);
-                cnt->icsb_icount += cntp->icsb_icount;
-                cnt->icsb_ifree += cntp->icsb_ifree;
-                cnt->icsb_fdblocks += cntp->icsb_fdblocks;
-        }
-
-        if (!(flags & XFS_ICSB_LAZY_COUNT))
-                xfs_icsb_unlock_all_counters(mp);
-}
-
-STATIC int
-xfs_icsb_counter_disabled(
-        xfs_mount_t     *mp,
-        xfs_sb_field_t  field)
-{
-        ASSERT((field >= XFS_SBS_ICOUNT) && (field <= XFS_SBS_FDBLOCKS));
-        return test_bit(field, &mp->m_icsb_counters);
-}
-
-STATIC void
-xfs_icsb_disable_counter(
-        xfs_mount_t     *mp,
-        xfs_sb_field_t  field)
-{
-        xfs_icsb_cnts_t cnt;
-
-        ASSERT((field >= XFS_SBS_ICOUNT) && (field <= XFS_SBS_FDBLOCKS));
-
-        /*
-         * If we are already disabled, then there is nothing to do
-         * here. We check before locking all the counters to avoid
-         * the expensive lock operation when being called in the
-         * slow path and the counter is already disabled. This is
-         * safe because the only time we set or clear this state is under
-         * the m_icsb_mutex.
-         */
-        if (xfs_icsb_counter_disabled(mp, field))
-                return;
-
-        xfs_icsb_lock_all_counters(mp);
-        if (!test_and_set_bit(field, &mp->m_icsb_counters)) {
-                /* drain back to superblock */
-
-                xfs_icsb_count(mp, &cnt, XFS_ICSB_LAZY_COUNT);
-                switch(field) {
-                case XFS_SBS_ICOUNT:
-                        mp->m_sb.sb_icount = cnt.icsb_icount;
-                        break;
-                case XFS_SBS_IFREE:
-                        mp->m_sb.sb_ifree = cnt.icsb_ifree;
-                        break;
-                case XFS_SBS_FDBLOCKS:
-                        mp->m_sb.sb_fdblocks = cnt.icsb_fdblocks;
-                        break;
-                default:
-                        BUG();
-                }
-        }
-
-        xfs_icsb_unlock_all_counters(mp);
-}
-
-STATIC void
-xfs_icsb_enable_counter(
-        xfs_mount_t     *mp,
-        xfs_sb_field_t  field,
-        uint64_t        count,
-        uint64_t        resid)
-{
-        xfs_icsb_cnts_t *cntp;
-        int             i;
-
-        ASSERT((field >= XFS_SBS_ICOUNT) && (field <= XFS_SBS_FDBLOCKS));
-
-        xfs_icsb_lock_all_counters(mp);
-        for_each_online_cpu(i) {
-                cntp = per_cpu_ptr(mp->m_sb_cnts, i);
-                switch (field) {
-                case XFS_SBS_ICOUNT:
-                        cntp->icsb_icount = count + resid;
-                        break;
-                case XFS_SBS_IFREE:
-                        cntp->icsb_ifree = count + resid;
-                        break;
-                case XFS_SBS_FDBLOCKS:
-                        cntp->icsb_fdblocks = count + resid;
-                        break;
-                default:
-                        BUG();
-                        break;
-                }
-                resid = 0;
-        }
-        clear_bit(field, &mp->m_icsb_counters);
-        xfs_icsb_unlock_all_counters(mp);
-}
-
-void
-xfs_icsb_sync_counters_locked(
-        xfs_mount_t     *mp,
-        int             flags)
-{
-        xfs_icsb_cnts_t cnt;
-
-        xfs_icsb_count(mp, &cnt, flags);
-
-        if (!xfs_icsb_counter_disabled(mp, XFS_SBS_ICOUNT))
-                mp->m_sb.sb_icount = cnt.icsb_icount;
-        if (!xfs_icsb_counter_disabled(mp, XFS_SBS_IFREE))
-                mp->m_sb.sb_ifree = cnt.icsb_ifree;
-        if (!xfs_icsb_counter_disabled(mp, XFS_SBS_FDBLOCKS))
-                mp->m_sb.sb_fdblocks = cnt.icsb_fdblocks;
-}
-
-/*
- * Accurate update of per-cpu counters to incore superblock
- */
-void
-xfs_icsb_sync_counters(
-        xfs_mount_t     *mp,
-        int             flags)
-{
-        spin_lock(&mp->m_sb_lock);
-        xfs_icsb_sync_counters_locked(mp, flags);
-        spin_unlock(&mp->m_sb_lock);
-}
-
-/*
- * Balance and enable/disable counters as necessary.
- *
- * Thresholds for re-enabling counters are somewhat magic.  inode counts are
- * chosen to be the same number as single on disk allocation chunk per CPU, and
- * free blocks is something far enough zero that we aren't going thrash when we
- * get near ENOSPC. We also need to supply a minimum we require per cpu to
- * prevent looping endlessly when xfs_alloc_space asks for more than will
- * be distributed to a single CPU but each CPU has enough blocks to be
- * reenabled.
- *
- * Note that we can be called when counters are already disabled.
- * xfs_icsb_disable_counter() optimises the counter locking in this case to
- * prevent locking every per-cpu counter needlessly.
- */
-
-#define XFS_ICSB_INO_CNTR_REENABLE      (uint64_t)64
-#define XFS_ICSB_FDBLK_CNTR_REENABLE(mp) \
-                (uint64_t)(512 + XFS_ALLOC_SET_ASIDE(mp))
-STATIC void
-xfs_icsb_balance_counter_locked(
-        xfs_mount_t     *mp,
-        xfs_sb_field_t  field,
-        int             min_per_cpu)
-{
-        uint64_t        count, resid;
-        int             weight = num_online_cpus();
-        uint64_t        min = (uint64_t)min_per_cpu;
-
-        /* disable counter and sync counter */
-        xfs_icsb_disable_counter(mp, field);
-
-        /* update counters  - first CPU gets residual*/
-        switch (field) {
-        case XFS_SBS_ICOUNT:
-                count = mp->m_sb.sb_icount;
-                resid = do_div(count, weight);
-                if (count < max(min, XFS_ICSB_INO_CNTR_REENABLE))
-                        return;
-                break;
-        case XFS_SBS_IFREE:
-                count = mp->m_sb.sb_ifree;
-                resid = do_div(count, weight);
-                if (count < max(min, XFS_ICSB_INO_CNTR_REENABLE))
-                        return;
-                break;
-        case XFS_SBS_FDBLOCKS:
-                count = mp->m_sb.sb_fdblocks;
-                resid = do_div(count, weight);
-                if (count < max(min, XFS_ICSB_FDBLK_CNTR_REENABLE(mp)))
-                        return;
-                break;
-        default:
-                BUG();
-                count = resid = 0;      /* quiet, gcc */
-                break;
-        }
-
-        xfs_icsb_enable_counter(mp, field, count, resid);
-}
-
-STATIC void
-xfs_icsb_balance_counter(
-        xfs_mount_t     *mp,
-        xfs_sb_field_t  fields,
-        int             min_per_cpu)
-{
-        spin_lock(&mp->m_sb_lock);
-        xfs_icsb_balance_counter_locked(mp, fields, min_per_cpu);
-        spin_unlock(&mp->m_sb_lock);
-}
-
-int
-xfs_icsb_modify_counters(
-        xfs_mount_t     *mp,
-        xfs_sb_field_t  field,
-        int64_t         delta,
-        int             rsvd)
-{
-        xfs_icsb_cnts_t *icsbp;
-        long long       lcounter;       /* long counter for 64 bit fields */
-        int             ret = 0;
-
-        might_sleep();
-again:
-        preempt_disable();
-        icsbp = this_cpu_ptr(mp->m_sb_cnts);
-
-        /*
-         * if the counter is disabled, go to slow path
-         */
-        if (unlikely(xfs_icsb_counter_disabled(mp, field)))
-                goto slow_path;
-        xfs_icsb_lock_cntr(icsbp);
-        if (unlikely(xfs_icsb_counter_disabled(mp, field))) {
-                xfs_icsb_unlock_cntr(icsbp);
-                goto slow_path;
-        }
-
-        switch (field) {
-        case XFS_SBS_ICOUNT:
-                lcounter = icsbp->icsb_icount;
-                lcounter += delta;
-                if (unlikely(lcounter < 0))
-                        goto balance_counter;
-                icsbp->icsb_icount = lcounter;
-                break;
-
-        case XFS_SBS_IFREE:
-                lcounter = icsbp->icsb_ifree;
-                lcounter += delta;
-                if (unlikely(lcounter < 0))
-                        goto balance_counter;
-                icsbp->icsb_ifree = lcounter;
-                break;
-
-        case XFS_SBS_FDBLOCKS:
-                BUG_ON((mp->m_resblks - mp->m_resblks_avail) != 0);
-
-                lcounter = icsbp->icsb_fdblocks - XFS_ALLOC_SET_ASIDE(mp);
-                lcounter += delta;
-                if (unlikely(lcounter < 0))
-                        goto balance_counter;
-                icsbp->icsb_fdblocks = lcounter + XFS_ALLOC_SET_ASIDE(mp);
-                break;
-        default:
-                BUG();
-                break;
-        }
-        xfs_icsb_unlock_cntr(icsbp);
-        preempt_enable();
-        return 0;
-
-slow_path:
-        preempt_enable();
-
-        /*
-         * serialise with a mutex so we don't burn lots of cpu on
-         * the superblock lock. We still need to hold the superblock
-         * lock, however, when we modify the global structures.
-         */
-        xfs_icsb_lock(mp);
-
-        /*
-         * Now running atomically.
-         *
-         * If the counter is enabled, someone has beaten us to rebalancing.
-         * Drop the lock and try again in the fast path....
-         */
-        if (!(xfs_icsb_counter_disabled(mp, field))) {
-                xfs_icsb_unlock(mp);
-                goto again;
-        }
-
-        /*
-         * The counter is currently disabled. Because we are
-         * running atomically here, we know a rebalance cannot
-         * be in progress. Hence we can go straight to operating
-         * on the global superblock. We do not call xfs_mod_incore_sb()
-         * here even though we need to get the m_sb_lock. Doing so
-         * will cause us to re-enter this function and deadlock.
-         * Hence we get the m_sb_lock ourselves and then call
-         * xfs_mod_incore_sb_unlocked() as the unlocked path operates
-         * directly on the global counters.
-         */
-        spin_lock(&mp->m_sb_lock);
-        ret = xfs_mod_incore_sb_unlocked(mp, field, delta, rsvd);
-        spin_unlock(&mp->m_sb_lock);
-
-        /*
-         * Now that we've modified the global superblock, we
-         * may be able to re-enable the distributed counters
-         * (e.g. lots of space just got freed). After that
-         * we are done.
-         */
-        if (ret != -ENOSPC)
-                xfs_icsb_balance_counter(mp, field, 0);
-        xfs_icsb_unlock(mp);
-        return ret;
-
-balance_counter:
-        xfs_icsb_unlock_cntr(icsbp);
-        preempt_enable();
-
-        /*
-         * We may have multiple threads here if multiple per-cpu
-         * counters run dry at the same time. This will mean we can
-         * do more balances than strictly necessary but it is not
-         * the common slowpath case.
-         */
-        xfs_icsb_lock(mp);
-
-        /*
-         * running atomically.
-         *
-         * This will leave the counter in the correct state for future
-         * accesses. After the rebalance, we simply try again and our retry
-         * will either succeed through the fast path or slow path without
-         * another balance operation being required.
-         */
-        xfs_icsb_balance_counter(mp, field, delta);
-        xfs_icsb_unlock(mp);
-        goto again;
-}
-
-#endif