fs: scale files_lock

[net-next-2.6.git] / fs / super.c

diff --git a/fs/super.c b/fs/super.c
index bd9eea4bb2bbe768beab53f07c61e98c8505f404..8819e3a7ff203fb521b537672d16d5e2d4cea80d 100644 (file)
--- a/fs/super.c
+++ b/fs/super.c
@@ -54,7 +54,22 @@ static struct super_block *alloc_super(struct file_system_type *type)
                        s = NULL;
                        goto out;
                }
+#ifdef CONFIG_SMP
+               s->s_files = alloc_percpu(struct list_head);
+               if (!s->s_files) {
+                       security_sb_free(s);
+                       kfree(s);
+                       s = NULL;
+                       goto out;
+               } else {
+                       int i;
+
+                       for_each_possible_cpu(i)
+                               INIT_LIST_HEAD(per_cpu_ptr(s->s_files, i));
+               }
+#else
                INIT_LIST_HEAD(&s->s_files);
+#endif
                INIT_LIST_HEAD(&s->s_instances);
                INIT_HLIST_HEAD(&s->s_anon);
                INIT_LIST_HEAD(&s->s_inodes);
@@ -108,6 +123,9 @@ out:
  */
 static inline void destroy_super(struct super_block *s)
 {
+#ifdef CONFIG_SMP
+       free_percpu(s->s_files);
+#endif
        security_sb_free(s);
        kfree(s->s_subtype);
        kfree(s->s_options);
@@ -363,10 +381,10 @@ EXPORT_SYMBOL(drop_super);
  */
 void sync_supers(void)
 {
-       struct super_block *sb, *n;
+       struct super_block *sb, *p = NULL;
 
        spin_lock(&sb_lock);
-       list_for_each_entry_safe(sb, n, &super_blocks, s_list) {
+       list_for_each_entry(sb, &super_blocks, s_list) {
                if (list_empty(&sb->s_instances))
                        continue;
                if (sb->s_op->write_super && sb->s_dirt) {
@@ -379,11 +397,13 @@ void sync_supers(void)
                        up_read(&sb->s_umount);
 
                        spin_lock(&sb_lock);
-                       /* lock was dropped, must reset next */
-                       list_safe_reset_next(sb, n, s_list);
-                       __put_super(sb);
+                       if (p)
+                               __put_super(p);
+                       p = sb;
                }
        }
+       if (p)
+               __put_super(p);
        spin_unlock(&sb_lock);
 }
 
@@ -397,10 +417,10 @@ void sync_supers(void)
  */
 void iterate_supers(void (*f)(struct super_block *, void *), void *arg)
 {
-       struct super_block *sb, *n;
+       struct super_block *sb, *p = NULL;
 
        spin_lock(&sb_lock);
-       list_for_each_entry_safe(sb, n, &super_blocks, s_list) {
+       list_for_each_entry(sb, &super_blocks, s_list) {
                if (list_empty(&sb->s_instances))
                        continue;
                sb->s_count++;
@@ -412,10 +432,12 @@ void iterate_supers(void (*f)(struct super_block *, void *), void *arg)
                up_read(&sb->s_umount);
 
                spin_lock(&sb_lock);
-               /* lock was dropped, must reset next */
-               list_safe_reset_next(sb, n, s_list);
-               __put_super(sb);
+               if (p)
+                       __put_super(p);
+               p = sb;
        }
+       if (p)
+               __put_super(p);
        spin_unlock(&sb_lock);
 }
 
@@ -577,10 +599,10 @@ int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
 
 static void do_emergency_remount(struct work_struct *work)
 {
-       struct super_block *sb, *n;
+       struct super_block *sb, *p = NULL;
 
        spin_lock(&sb_lock);
-       list_for_each_entry_safe(sb, n, &super_blocks, s_list) {
+       list_for_each_entry(sb, &super_blocks, s_list) {
                if (list_empty(&sb->s_instances))
                        continue;
                sb->s_count++;
@@ -594,10 +616,12 @@ static void do_emergency_remount(struct work_struct *work)
                }
                up_write(&sb->s_umount);
                spin_lock(&sb_lock);
-               /* lock was dropped, must reset next */
-               list_safe_reset_next(sb, n, s_list);
-               __put_super(sb);
+               if (p)
+                       __put_super(p);
+               p = sb;
        }
+       if (p)
+               __put_super(p);
        spin_unlock(&sb_lock);
        kfree(work);
        printk("Emergency Remount complete\n");