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Commit e8234a68 authored by David Chinner's avatar David Chinner Committed by Nathan Scott
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[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: default avatarDavid Chinner <dgc@sgi.com>
Signed-off-by: default avatarNathan Scott <nathans@sgi.com>
parent 2d0f864b

fs/xfs/linux-2.6/xfs_linux.h

+2 −0
Original line number Diff line number Diff line
@@ -73,6 +73,8 @@ 
#include <linux/list.h>

#include <linux/proc_fs.h>

#include <linux/sort.h>

#include <linux/cpu.h>

#include <linux/notifier.h>



#include <asm/page.h>

#include <asm/div64.h>

fs/xfs/xfs_mount.c

+72 −2
Original line number Diff line number Diff line
@@ -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);
@@ -1746,9 +1814,11 @@ 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);

	}

}





STATIC inline void

fs/xfs/xfs_mount.h

+1 −0
Original line number Diff line number Diff line
@@ -401,6 +401,7 @@ typedef struct xfs_mount { 
#ifdef HAVE_PERCPU_SB

	xfs_icsb_cnts_t		*m_sb_cnts;	/* per-cpu superblock counters */

	unsigned long		m_icsb_counters; /* disabled per-cpu counters */

	struct notifier_block	m_icsb_notifier; /* hotplug cpu notifier */

#endif

} xfs_mount_t;