inode: don't memset the inode address space twice

Noticed when looking at why cycling 600k inodes/s through the inode
cache was taking a total of 8% cpu in memset() during inode
initialisation.  There is no need to zero the inode.i_data structure
twice.

This increases single threaded bulkstat throughput from ~200,000
inodes/s to ~220,000 inodes/s, so we save a substantial amount of
CPU time per inode init by doing this.

Signed-Off-By: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

diff --git a/fs/inode.c b/fs/inode.c
index 6295f1415761f9106e78e8fb5f959f206ecb6792..b153aeaa61ea5fd37c6b9fa7261e5c56967c2de1 100644 (file)
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -346,9 +346,8 @@ void inc_nlink(struct inode *inode)
 }
 EXPORT_SYMBOL(inc_nlink);
 
-void address_space_init_once(struct address_space *mapping)
+static void __address_space_init_once(struct address_space *mapping)
 {
-       memset(mapping, 0, sizeof(*mapping));
        INIT_RADIX_TREE(&mapping->page_tree, GFP_ATOMIC | __GFP_ACCOUNT);
        spin_lock_init(&mapping->tree_lock);
        init_rwsem(&mapping->i_mmap_rwsem);
@@ -356,6 +355,12 @@ void address_space_init_once(struct address_space *mapping)
        spin_lock_init(&mapping->private_lock);
        mapping->i_mmap = RB_ROOT_CACHED;
 }
+
+void address_space_init_once(struct address_space *mapping)
+{
+       memset(mapping, 0, sizeof(*mapping));
+       __address_space_init_once(mapping);
+}
 EXPORT_SYMBOL(address_space_init_once);
 
 /*
@@ -371,7 +376,7 @@ void inode_init_once(struct inode *inode)
        INIT_LIST_HEAD(&inode->i_io_list);
        INIT_LIST_HEAD(&inode->i_wb_list);
        INIT_LIST_HEAD(&inode->i_lru);
-       address_space_init_once(&inode->i_data);
+       __address_space_init_once(&inode->i_data);
        i_size_ordered_init(inode);
 }
 EXPORT_SYMBOL(inode_init_once);