From 23bfc2a24ea3d993cc5cc90c9970654e7232502e Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Mon, 13 Oct 2014 15:52:14 -0700 Subject: autofs4: allow RCU-walk to walk through autofs4 This series teaches autofs about RCU-walk so that we don't drop straight into REF-walk when we hit an autofs directory, and so that we avoid spinlocks as much as possible when performing an RCU-walk. This is needed so that the benefits of the recent NFS support for RCU-walk are fully available when NFS filesystems are automounted. Patches have been carefully reviewed and tested both with test suites and in production - thanks a lot to Ian Kent for his support there. This patch (of 6): Any attempt to look up a pathname that passes though an autofs4 mount is currently forced out of RCU-walk into REF-walk. This can significantly hurt performance of many-thread work loads on many-core systems, especially if the automounted filesystem supports RCU-walk but doesn't get to benefit from it. So if autofs4_d_manage is called with rcu_walk set, only fail with -ECHILD if it is necessary to wait longer than a spinlock. Signed-off-by: NeilBrown Reviewed-by: Ian Kent Tested-by: Ian Kent Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/autofs4/autofs_i.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/autofs4/autofs_i.h') diff --git a/fs/autofs4/autofs_i.h b/fs/autofs4/autofs_i.h index 9e359fb20c0a..2f1032f12d91 100644 --- a/fs/autofs4/autofs_i.h +++ b/fs/autofs4/autofs_i.h @@ -148,7 +148,7 @@ void autofs4_free_ino(struct autofs_info *); /* Expiration */ int is_autofs4_dentry(struct dentry *); -int autofs4_expire_wait(struct dentry *dentry); +int autofs4_expire_wait(struct dentry *dentry, int rcu_walk); int autofs4_expire_run(struct super_block *, struct vfsmount *, struct autofs_sb_info *, struct autofs_packet_expire __user *); -- cgit v1.2.3-59-g8ed1b