#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 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;
}
/*
}
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
projects / firefly-linux-kernel-4.4.55.git / blobdiff