async: make the final inode deletion an asynchronous event

this makes "rm -rf" on a (names cached) kernel tree go from
11.6 to 8.6 seconds on an ext3 filesystem

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>

3 files changed, 28 insertions, 7 deletions

diff --git a/fs/inode.c b/fs/inode.c
index 7a6e8c2ff7b1..0013ac1af8e7 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -22,6 +22,7 @@
 #include <linux/bootmem.h>
 #include <linux/inotify.h>
 #include <linux/mount.h>
+#include <linux/async.h>
 
 /*
  * This is needed for the following functions:
@@ -1138,16 +1139,11 @@ EXPORT_SYMBOL(remove_inode_hash);
  * I_FREEING is set so that no-one will take a new reference to the inode while
  * it is being deleted.
  */
-void generic_delete_inode(struct inode *inode)
+static void generic_delete_inode_async(void *data, async_cookie_t cookie)
 {
+        struct inode *inode = data;
         const struct super_operations *op = inode->i_sb->s_op;
 
-        list_del_init(&inode->i_list);
-        list_del_init(&inode->i_sb_list);
-        inode->i_state |= I_FREEING;
-        inodes_stat.nr_inodes--;
-        spin_unlock(&inode_lock);
-
         security_inode_delete(inode);
 
         if (op->delete_inode) {
@@ -1171,6 +1167,16 @@ void generic_delete_inode(struct inode *inode)
         destroy_inode(inode);
 }
 
+void generic_delete_inode(struct inode *inode)
+{
+        list_del_init(&inode->i_list);
+        list_del_init(&inode->i_sb_list);
+        inode->i_state |= I_FREEING;
+        inodes_stat.nr_inodes--;
+        spin_unlock(&inode_lock);
+        async_schedule_special(generic_delete_inode_async, inode, &inode->i_sb->s_async_list);
+}
+
 EXPORT_SYMBOL(generic_delete_inode);
 
 static void generic_forget_inode(struct inode *inode)
diff --git a/fs/super.c b/fs/super.c
index ddba069d7a99..cb20744ec789 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -38,6 +38,7 @@
 #include <linux/kobject.h>
 #include <linux/mutex.h>
 #include <linux/file.h>
+#include <linux/async.h>
 #include <asm/uaccess.h>
 #include "internal.h"
 
@@ -71,6 +72,7 @@ static struct super_block *alloc_super(struct file_system_type *type)
                 INIT_HLIST_HEAD(&s->s_anon);
                 INIT_LIST_HEAD(&s->s_inodes);
                 INIT_LIST_HEAD(&s->s_dentry_lru);
+                INIT_LIST_HEAD(&s->s_async_list);
                 init_rwsem(&s->s_umount);
                 mutex_init(&s->s_lock);
                 lockdep_set_class(&s->s_umount, &type->s_umount_key);
@@ -289,11 +291,18 @@ void generic_shutdown_super(struct super_block *sb)
 {
         const struct super_operations *sop = sb->s_op;
 
+
         if (sb->s_root) {
                 shrink_dcache_for_umount(sb);
                 fsync_super(sb);
                 lock_super(sb);
                 sb->s_flags &= ~MS_ACTIVE;
+
+                /*
+                 * wait for asynchronous fs operations to finish before going further
+                 */
+                async_synchronize_full_special(&sb->s_async_list);
+
                 /* bad name - it should be evict_inodes() */
                 invalidate_inodes(sb);
                 lock_kernel();
@@ -449,6 +458,7 @@ void sync_filesystems(int wait)
                 if (sb->s_flags & MS_RDONLY)
                         continue;
                 sb->s_need_sync_fs = 1;
+                async_synchronize_full_special(&sb->s_async_list);
         }
 
 restart:
diff --git a/include/linux/fs.h b/include/linux/fs.h
index d7eba77f666e..e38a64d71eff 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1184,6 +1184,11 @@ struct super_block {
          * generic_show_options()
          */
         char *s_options;
+
+        /*
+         * storage for asynchronous operations
+         */
+        struct list_head s_async_list;
 };
 
 extern struct timespec current_fs_time(struct super_block *sb);