From e8234a6871aa0de1ed0aeeecb5230ecf3ab414e2 Mon Sep 17 00:00:00 2001 From: David Chinner Date: Tue, 14 Mar 2006 13:23:52 +1100 Subject: [XFS] Add support for hotplug CPUs to the per-CPU superblock counters by registering a notifier callback that listens to CPU up/down events to modify the counters appropriately. SGI-PV: 949726 SGI-Modid: xfs-linux-melb:xfs-kern:25214a Signed-off-by: David Chinner Signed-off-by: Nathan Scott --- fs/xfs/xfs_mount.c | 74 ++++++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 72 insertions(+), 2 deletions(-) (limited to 'fs/xfs/xfs_mount.c') diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c index 9b43b7b..a64110b 100644 --- a/fs/xfs/xfs_mount.c +++ b/fs/xfs/xfs_mount.c @@ -60,6 +60,7 @@ STATIC int xfs_icsb_modify_counters(xfs_mount_t *, xfs_sb_field_t, int, int); STATIC int xfs_icsb_modify_counters_locked(xfs_mount_t *, xfs_sb_field_t, int, int); +STATIC int xfs_icsb_disable_counter(xfs_mount_t *, xfs_sb_field_t); #else @@ -1716,9 +1717,72 @@ xfs_mount_log_sbunit( * 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). + */ + +/* + * hot-plug CPU notifier support. * - * Note: hotplug CPUs not yet supported + * We cannot use the hotcpu_register() function because it does + * not allow notifier instances. We need a notifier per filesystem + * as we need to be able to identify the filesystem to balance + * the counters out. This is acheived 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; + int s; + + 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: + /* Easy Case - initialize the area and locks, and + * then rebalance when online does everything else for us. */ + spin_lock_init(&cntp->icsb_lock); + cntp->icsb_icount = 0; + cntp->icsb_ifree = 0; + cntp->icsb_fdblocks = 0; + break; + case CPU_ONLINE: + 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); + break; + case CPU_DEAD: + /* Disable all the counters, then fold the dead cpu's + * count into the total on the global superblock and + * re-enable the counters. */ + s = XFS_SB_LOCK(mp); + 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; + + cntp->icsb_icount = 0; + cntp->icsb_ifree = 0; + cntp->icsb_fdblocks = 0; + + xfs_icsb_balance_counter(mp, XFS_SBS_ICOUNT, XFS_ICSB_SB_LOCKED); + xfs_icsb_balance_counter(mp, XFS_SBS_IFREE, XFS_ICSB_SB_LOCKED); + xfs_icsb_balance_counter(mp, XFS_SBS_FDBLOCKS, XFS_ICSB_SB_LOCKED); + XFS_SB_UNLOCK(mp, s); + break; + } + + return NOTIFY_OK; +} + int xfs_icsb_init_counters( xfs_mount_t *mp) @@ -1730,6 +1794,10 @@ xfs_icsb_init_counters( if (mp->m_sb_cnts == NULL) return -ENOMEM; + mp->m_icsb_notifier.notifier_call = xfs_icsb_cpu_notify; + mp->m_icsb_notifier.priority = 0; + register_cpu_notifier(&mp->m_icsb_notifier); + for_each_online_cpu(i) { cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i); spin_lock_init(&cntp->icsb_lock); @@ -1746,8 +1814,10 @@ STATIC void xfs_icsb_destroy_counters( xfs_mount_t *mp) { - if (mp->m_sb_cnts) + if (mp->m_sb_cnts) { + unregister_cpu_notifier(&mp->m_icsb_notifier); free_percpu(mp->m_sb_cnts); + } } -- cgit v1.1