We can use ilog2() in fs/namespace.c to compute hash_bits and hash_mask at
compile time, not runtime.
Signed-off-by: Eric Dumazet <[email protected]>
diff --git a/fs/namespace.c b/fs/namespace.c
index 0608388..835f14a 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -25,6 +25,7 @@
#include <linux/security.h>
#include <linux/mount.h>
#include <linux/ramfs.h>
+#include <linux/log2.h>
#include <asm/uaccess.h>
#include <asm/unistd.h>
#include "pnode.h"
@@ -36,7 +37,8 @@ __cacheline_aligned_in_smp DEFINE_SPINLOCK(vfsmount_lock);
static int event;
static struct list_head *mount_hashtable __read_mostly;
-static int hash_mask __read_mostly, hash_bits __read_mostly;
+#define hash_bits ilog2(PAGE_SIZE / sizeof(struct list_head))
+#define hash_mask ((1UL << hash_bits) - 1)
static struct kmem_cache *mnt_cache __read_mostly;
static struct rw_semaphore namespace_sem;
@@ -1828,24 +1830,7 @@ void __init mnt_init(void)
if (!mount_hashtable)
panic("Failed to allocate mount hash table\n");
- /*
- * Find the power-of-two list-heads that can fit into the allocation..
- * We don't guarantee that "sizeof(struct list_head)" is necessarily
- * a power-of-two.
- */
- nr_hash = PAGE_SIZE / sizeof(struct list_head);
- hash_bits = 0;
- do {
- hash_bits++;
- } while ((nr_hash >> hash_bits) != 0);
- hash_bits--;
-
- /*
- * Re-calculate the actual number of entries and the mask
- * from the number of bits we can fit.
- */
nr_hash = 1UL << hash_bits;
- hash_mask = nr_hash - 1;
printk("Mount-cache hash table entries: %d\n", nr_hash);
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