#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;
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;
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.
}
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_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);
-
- memset(cntp, 0, sizeof(xfs_icsb_cnts_t));
-
- 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 error;
- int i;
-
- error = percpu_counter_init(&mp->m_icount, 0, GFP_KERNEL);
- if (error)
- return error;
-
- error = percpu_counter_init(&mp->m_ifree, 0, GFP_KERNEL);
- if (error)
- goto free_icount;
-
- error = percpu_counter_init(&mp->m_fdblocks, 0, GFP_KERNEL);
- if (error)
- goto free_ifree;
-
- mp->m_sb_cnts = alloc_percpu(xfs_icsb_cnts_t);
- if (!mp->m_sb_cnts) {
- error = -ENOMEM;
- goto free_fdblocks;
- }
-
- 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;
-
-free_fdblocks:
- percpu_counter_destroy(&mp->m_fdblocks);
-free_ifree:
- percpu_counter_destroy(&mp->m_ifree);
-free_icount:
- percpu_counter_destroy(&mp->m_icount);
- return error;
-}
-
-void
-xfs_icsb_reinit_counters(
- xfs_mount_t *mp)
-{
- percpu_counter_set(&mp->m_icount, mp->m_sb.sb_icount);
- percpu_counter_set(&mp->m_ifree, mp->m_sb.sb_ifree);
- percpu_counter_set(&mp->m_fdblocks, mp->m_sb.sb_fdblocks);
-
- 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_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);
- }
-
- percpu_counter_destroy(&mp->m_icount);
- percpu_counter_destroy(&mp->m_ifree);
- percpu_counter_destroy(&mp->m_fdblocks);
-
- 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)
-{
- memset(cnt, 0, sizeof(xfs_icsb_cnts_t));
-
- if (!(flags & XFS_ICSB_LAZY_COUNT))
- xfs_icsb_lock_all_counters(mp);
-
-
- 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)
-{
- 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;
-
- /*
- * 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) {
- 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)
-{
- int i;
-
- xfs_icsb_lock_all_counters(mp);
- for_each_online_cpu(i) {
- switch (field) {
- 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);
-}
-
-/*
- * 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;
-
- /* disable counter and sync counter */
- xfs_icsb_disable_counter(mp, field);
-
- /* update counters - first CPU gets residual*/
- switch (field) {
- 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;
- 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) {
- default:
- BUG();
- goto balance_counter; /* be still, gcc */
- }
- 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
projects / deliverable / linux.git / blobdiff