Resend. Replace the buffer lru spinlock protection with
local_irq_disable and a cross-CPU call to invalidate them.
buffer.c | 75 ++++++++++++++++++++++++++++++++++++++++-----------------------
1 files changed, 48 insertions(+), 27 deletions(-)
--- 2.5.31/fs/buffer.c~buffer-lru-lock Sat Aug 10 23:27:26 2002
+++ 2.5.31-akpm/fs/buffer.c Sat Aug 10 23:27:26 2002
@@ -1277,15 +1277,32 @@ __bread_slow(struct block_device *bdev,
*
* This is a transparent caching front-end to sb_bread(), sb_getblk() and
* sb_find_get_block().
+ *
+ * The LRUs themselves only need locking against invalidate_bh_lrus. We use
+ * a local interrupt disable for that.
*/
-#define BH_LRU_SIZE 7
+#define BH_LRU_SIZE 8
static struct bh_lru {
- spinlock_t lock;
struct buffer_head *bhs[BH_LRU_SIZE];
} ____cacheline_aligned_in_smp bh_lrus[NR_CPUS];
+#ifdef CONFIG_SMP
+#define bh_lru_lock() local_irq_disable()
+#define bh_lru_unlock() local_irq_enable()
+#else
+#define bh_lru_lock() preempt_disable()
+#define bh_lru_unlock() preempt_enable()
+#endif
+
+static inline void check_irqs_on(void)
+{
+#ifdef irqs_disabled
+ BUG_ON(irqs_disabled());
+#endif
+}
+
/*
* The LRU management algorithm is dopey-but-simple. Sorry.
*/
@@ -1297,8 +1314,9 @@ static void bh_lru_install(struct buffer
if (bh == NULL)
return;
- lru = &bh_lrus[get_cpu()];
- spin_lock(&lru->lock);
+ check_irqs_on();
+ bh_lru_lock();
+ lru = &bh_lrus[smp_processor_id()];
if (lru->bhs[0] != bh) {
struct buffer_head *bhs[BH_LRU_SIZE];
int in;
@@ -1324,8 +1342,7 @@ static void bh_lru_install(struct buffer
bhs[out++] = NULL;
memcpy(lru->bhs, bhs, sizeof(bhs));
}
- spin_unlock(&lru->lock);
- put_cpu();
+ bh_lru_unlock();
if (evictee) {
touch_buffer(evictee);
@@ -1340,8 +1357,9 @@ lookup_bh(struct block_device *bdev, sec
struct bh_lru *lru;
int i;
- lru = &bh_lrus[get_cpu()];
- spin_lock(&lru->lock);
+ check_irqs_on();
+ bh_lru_lock();
+ lru = &bh_lrus[smp_processor_id()];
for (i = 0; i < BH_LRU_SIZE; i++) {
struct buffer_head *bh = lru->bhs[i];
@@ -1359,8 +1377,7 @@ lookup_bh(struct block_device *bdev, sec
break;
}
}
- spin_unlock(&lru->lock);
- put_cpu();
+ bh_lru_unlock();
return ret;
}
@@ -1407,26 +1424,33 @@ __bread(struct block_device *bdev, secto
EXPORT_SYMBOL(__bread);
/*
- * This is called rarely - at unmount.
+ * invalidate_bh_lrus() is called rarely - at unmount. Because it is only for
+ * unmount it only needs to ensure that all buffers from the target device are
+ * invalidated on return and it doesn't need to worry about new buffers from
+ * that device being added - the unmount code has to prevent that.
*/
-static void invalidate_bh_lrus(void)
+static void invalidate_bh_lru(void *arg)
{
- int cpu_idx;
+ const int cpu = get_cpu();
+ int i;
- for (cpu_idx = 0; cpu_idx < NR_CPUS; cpu_idx++)
- spin_lock(&bh_lrus[cpu_idx].lock);
- for (cpu_idx = 0; cpu_idx < NR_CPUS; cpu_idx++) {
- int i;
-
- for (i = 0; i < BH_LRU_SIZE; i++) {
- brelse(bh_lrus[cpu_idx].bhs[i]);
- bh_lrus[cpu_idx].bhs[i] = NULL;
- }
+ for (i = 0; i < BH_LRU_SIZE; i++) {
+ brelse(bh_lrus[cpu].bhs[i]);
+ bh_lrus[cpu].bhs[i] = NULL;
}
- for (cpu_idx = 0; cpu_idx < NR_CPUS; cpu_idx++)
- spin_unlock(&bh_lrus[cpu_idx].lock);
+ put_cpu();
+}
+
+static void invalidate_bh_lrus(void)
+{
+ preempt_disable();
+ invalidate_bh_lru(NULL);
+ smp_call_function(invalidate_bh_lru, NULL, 1, 1);
+ preempt_enable();
}
+
+
void set_bh_page(struct buffer_head *bh,
struct page *page, unsigned long offset)
{
@@ -2554,9 +2578,6 @@ void __init buffer_init(void)
{
int i;
- for (i = 0; i < NR_CPUS; i++)
- spin_lock_init(&bh_lrus[i].lock);
-
bh_cachep = kmem_cache_create("buffer_head",
sizeof(struct buffer_head), 0,
SLAB_HWCACHE_ALIGN, init_buffer_head, NULL);
.
-
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This archive was generated by hypermail 2b29 : Thu Aug 15 2002 - 22:00:23 EST