[SSI] openssi/kernel/cluster/ssi/cfs cfsproc.c,1.34,1.35

Update of /cvsroot/ssic-linux/openssi/kernel/cluster/ssi/cfs
In directory fdv4jf1.ch3.sourceforge.com:/tmp/cvs-serv9776/kernel/cluster/ssi/cfs

Modified Files:
      Tag: OPENSSI-FC
	cfsproc.c 
Log Message:
CFS (#ifdef CFS_PAGES_CACHE):
- Use bitmap to represent set of cfs_pagevec's in cfs_pagevec_pool.
- Regression:
  - Stale page pointers in recycled cfs_pagevec slab when cfs_pagevec_pool is full.


Index: cfsproc.c
===================================================================
RCS file: /cvsroot/ssic-linux/openssi/kernel/cluster/ssi/cfs/cfsproc.c,v
retrieving revision 1.34
retrieving revision 1.35
diff -u -d -r1.34 -r1.35
--- cfsproc.c	27 Oct 2009 03:18:29 -0000	1.34
+++ cfsproc.c	18 Nov 2009 06:15:56 -0000	1.35
@@ -440,12 +440,15 @@
 #ifdef ICS_OOL_STRUCT_PAGES
 #ifdef CFS_PAGES_CACHE
 /* Manage the number of cfs_pagevec's in cache.
- * kmem_cache dtor is deprecated so we have to manage ourselves.
+ * kmem_cache destructor is deprecated so we have to manage ourselves.
  */
-static struct page **cfs_pagevec_pool[64];
-static DEFINE_SPINLOCK(cfs_pagevec_pool_lock);
+#define MAX_CFS_PAGEVECS (64)
+static __cacheline_aligned_in_smp DEFINE_SPINLOCK(cfs_pagevec_lock);
+static DECLARE_BITMAP(cfs_pagevec_bitmap, MAX_CFS_PAGEVECS);
+static struct page **cfs_pagevec_pool[MAX_CFS_PAGEVECS];
 
 static kmem_cache_t *cfs_pagevec_cachep;
+#define CFS_PAGEVEC_MAXLEN ((CFS_MAX_FILE_IO_SIZE + PAGE_SIZE - 1) >> PAGE_SHIFT)
 
 static void
 cfs_pagevec_ctor(void * foo, kmem_cache_t * cachep, unsigned long flags)
@@ -459,18 +462,19 @@
 void
 cfs_pagevec_init(void)
 {
-	size_t max_len = (CFS_MAX_FILE_IO_SIZE + PAGE_SIZE - 1) >> PAGE_SHIFT;
 	int i;
 
 	cfs_pagevec_cachep = kmem_cache_create("cfs_pagevec",
-				max_len * sizeof(struct page *), 0,
+				CFS_PAGEVEC_MAXLEN * sizeof(struct page *), 0,
 				SLAB_PANIC, cfs_pagevec_ctor, NULL);
 
 	dprintk("cfs_pagevec pool max entries: %u (%u pages)\n",
-		ARRAY_SIZE(cfs_pagevec_pool),
-		ARRAY_SIZE(cfs_pagevec_pool) * max_len);
-	for (i = 0; i < ARRAY_SIZE(cfs_pagevec_pool); i++)
+		MAX_CFS_PAGEVECS,
+		MAX_CFS_PAGEVECS * (unsigned)CFS_PAGEVEC_MAXLEN);
+
+	for (i = 0; i < MAX_CFS_PAGEVECS; i++)
 		cfs_pagevec_pool[i] = NULL;
+	bitmap_zero(cfs_pagevec_bitmap, MAX_CFS_PAGEVECS);
 }
 #endif /* CFS_PAGES_CACHE */
 
@@ -478,26 +482,19 @@
 cfs_pagevec_alloc(unsigned int len)
 {
 	struct page **pages = NULL;
-	int i, max_len;
+	int i;
 
 #ifdef CFS_PAGES_CACHE
-	rcu_read_lock();
-	for (i = 0; i < ARRAY_SIZE(cfs_pagevec_pool); i++) {
-		if (cfs_pagevec_pool[i]) {
-			spin_lock(&cfs_pagevec_pool_lock);
-			if (!cfs_pagevec_pool[i]) {
-				spin_unlock(&cfs_pagevec_pool_lock);
-				continue;
-			}
-			/* Re-use the pagevec */
-			pages = cfs_pagevec_pool[i];
-			cfs_pagevec_pool[i] = NULL;
-			spin_unlock(&cfs_pagevec_pool_lock);
-			break;
-		}
+	spin_lock(&cfs_pagevec_lock);
+
+	i = find_first_bit(cfs_pagevec_bitmap, MAX_CFS_PAGEVECS);
+	if (i < MAX_CFS_PAGEVECS) {
+		__clear_bit(i, cfs_pagevec_bitmap);
+		pages = cfs_pagevec_pool[i];
 	}
-	rcu_read_unlock();
-	if (!pages)
+	spin_unlock(&cfs_pagevec_lock);
+
+	if (i >= MAX_CFS_PAGEVECS)
 		pages = kmem_cache_alloc(cfs_pagevec_cachep, GFP_KERNEL|__GFP_NOFAIL);
 #else
 	unsigned int array_size;
@@ -506,8 +503,7 @@
 	pages = kmalloc_nofail(array_size);
 #endif /* !CFS_PAGES_CACHE */
 
-	max_len = (CFS_MAX_FILE_IO_SIZE + PAGE_SIZE - 1) >> PAGE_SHIFT;
-	BUG_ON(len > max_len);
+	BUG_ON(len > CFS_PAGEVEC_MAXLEN);
 
 	/* Dynamically allocate pages for the pagevec */
 	i = len - 1;
@@ -524,32 +520,24 @@
 cfs_pagevec_free(struct page ** pages)
 {
 #ifdef CFS_PAGES_CACHE
-	int i, max_len;
+	int i;
 
-	rcu_read_lock();
-	for (i = 0; i < ARRAY_SIZE(cfs_pagevec_pool); i++) {
-		if (!cfs_pagevec_pool[i]) {
-			spin_lock(&cfs_pagevec_pool_lock);
-			if (cfs_pagevec_pool[i]) {
-				spin_unlock(&cfs_pagevec_pool_lock);
-				continue;
-			}
-			/* Insert pagevec into pool for re-use */
-			cfs_pagevec_pool[i] = pages;
-			pages = NULL;
-			spin_unlock(&cfs_pagevec_pool_lock);
-			break;
-		}
+	spin_lock(&cfs_pagevec_lock);
+
+	i = find_first_zero_bit(cfs_pagevec_bitmap, MAX_CFS_PAGEVECS);
+	if (i < MAX_CFS_PAGEVECS) {
+		__set_bit(i, cfs_pagevec_bitmap);
+		cfs_pagevec_pool[i] = pages;
 	}
-	rcu_read_unlock();
-	if (pages) {
-		max_len = (CFS_MAX_FILE_IO_SIZE + PAGE_SIZE - 1) >> PAGE_SHIFT;
+	spin_unlock(&cfs_pagevec_lock);
 
+	if (i >= MAX_CFS_PAGEVECS) {
 		/* Do the kmem_cache destructor */
-		for (i = 0; i < max_len; i++) {
+		for (i = 0; i < CFS_PAGEVEC_MAXLEN; i++) {
 			if (!pages[i])
 				break;
 			__free_page(pages[i]);
+			pages[i] = NULL;
 		}
 
 		kmem_cache_free(cfs_pagevec_cachep, (void *)pages);


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