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authorDavid Chinner <dgc@sgi.com>2006-03-14 13:29:16 +1100
committerNathan Scott <nathans@sgi.com>2006-03-14 13:29:16 +1100
commit01e1b69cfcdcfdd5b405165eaba29428f8b18a7c (patch)
tree3ca7e8d0047ff03ca532f39b0fc4cd50381e8ecc /fs/xfs/xfs_mount.c
parent87cbc49cd4b773a972bce56c5dd09c4717f3285b (diff)
[XFS] using a spinlock per cpu for superblock counter exclusion results in
a preēmpt counter overflow at 256p and above. Change the exclusion mechanism to use atomic bit operations and busy wait loops to emulate the spin lock exclusion mechanism but without the preempt count issues. SGI-PV: 950027 SGI-Modid: xfs-linux-melb:xfs-kern:25338a Signed-off-by: David Chinner <dgc@sgi.com> Signed-off-by: Nathan Scott <nathans@sgi.com>
Diffstat (limited to 'fs/xfs/xfs_mount.c')
-rw-r--r--fs/xfs/xfs_mount.c37
1 files changed, 24 insertions, 13 deletions
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index a64110b9023b..d62aee027368 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -1746,10 +1746,7 @@ xfs_icsb_cpu_notify(
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;
+ memset(cntp, 0, sizeof(xfs_icsb_cnts_t));
break;
case CPU_ONLINE:
xfs_icsb_balance_counter(mp, XFS_SBS_ICOUNT, 0);
@@ -1769,9 +1766,7 @@ xfs_icsb_cpu_notify(
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;
+ memset(cntp, 0, sizeof(xfs_icsb_cnts_t));
xfs_icsb_balance_counter(mp, XFS_SBS_ICOUNT, XFS_ICSB_SB_LOCKED);
xfs_icsb_balance_counter(mp, XFS_SBS_IFREE, XFS_ICSB_SB_LOCKED);
@@ -1800,7 +1795,7 @@ xfs_icsb_init_counters(
for_each_online_cpu(i) {
cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i);
- spin_lock_init(&cntp->icsb_lock);
+ memset(cntp, 0, sizeof(xfs_icsb_cnts_t));
}
/*
* start with all counters disabled so that the
@@ -1820,6 +1815,22 @@ xfs_icsb_destroy_counters(
}
}
+STATIC inline 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 inline void
+xfs_icsb_unlock_cntr(
+ xfs_icsb_cnts_t *icsbp)
+{
+ clear_bit(XFS_ICSB_FLAG_LOCK, &icsbp->icsb_flags);
+}
+
STATIC inline void
xfs_icsb_lock_all_counters(
@@ -1830,7 +1841,7 @@ xfs_icsb_lock_all_counters(
for_each_online_cpu(i) {
cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i);
- spin_lock(&cntp->icsb_lock);
+ xfs_icsb_lock_cntr(cntp);
}
}
@@ -1843,7 +1854,7 @@ xfs_icsb_unlock_all_counters(
for_each_online_cpu(i) {
cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i);
- spin_unlock(&cntp->icsb_lock);
+ xfs_icsb_unlock_cntr(cntp);
}
}
@@ -2070,7 +2081,7 @@ xfs_icsb_modify_counters_int(
again:
cpu = get_cpu();
icsbp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, cpu),
- spin_lock(&icsbp->icsb_lock);
+ xfs_icsb_lock_cntr(icsbp);
if (unlikely(xfs_icsb_counter_disabled(mp, field)))
goto slow_path;
@@ -2104,7 +2115,7 @@ again:
BUG();
break;
}
- spin_unlock(&icsbp->icsb_lock);
+ xfs_icsb_unlock_cntr(icsbp);
put_cpu();
if (locked)
XFS_SB_UNLOCK(mp, s);
@@ -2120,7 +2131,7 @@ again:
* manner.
*/
slow_path:
- spin_unlock(&icsbp->icsb_lock);
+ xfs_icsb_unlock_cntr(icsbp);
put_cpu();
/* need to hold superblock incase we need