From: John McCutchan <ttb@tentacle.dhs.org>
Bypass an inotify-related fastpath spinlock and several function calls on
systems which have no inotify watches registered.
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
fs/inotify.c | 7 +++++++
1 files changed, 7 insertions(+)
diff -puN fs/inotify.c~inotify-speedup fs/inotify.c
--- devel/fs/inotify.c~inotify-speedup 2005-07-26 00:38:13.000000000 -0700
+++ devel-akpm/fs/inotify.c 2005-07-26 00:38:13.000000000 -0700
@@ -37,6 +37,7 @@
#include <asm/ioctls.h>
static atomic_t inotify_cookie;
+static atomic_t inotify_watches;
static kmem_cache_t *watch_cachep;
static kmem_cache_t *event_cachep;
@@ -420,6 +421,7 @@ static struct inotify_watch *create_watc
get_inotify_watch(watch);
atomic_inc(&dev->user->inotify_watches);
+ atomic_inc(&inotify_watches);
return watch;
}
@@ -452,6 +454,7 @@ static void remove_watch_no_event(struct
list_del(&watch->d_list);
atomic_dec(&dev->user->inotify_watches);
+ atomic_dec(&inotify_watches);
idr_remove(&dev->idr, watch->wd);
put_inotify_watch(watch);
}
@@ -530,6 +533,9 @@ void inotify_dentry_parent_queue_event(s
struct dentry *parent;
struct inode *inode;
+ if (!atomic_read (&inotify_watches))
+ return;
+
spin_lock(&dentry->d_lock);
parent = dentry->d_parent;
inode = parent->d_inode;
@@ -1039,6 +1045,7 @@ static int __init inotify_setup(void)
inotify_max_user_watches = 8192;
atomic_set(&inotify_cookie, 0);
+ atomic_set(&inotify_watches, 0);
watch_cachep = kmem_cache_create("inotify_watch_cache",
sizeof(struct inotify_watch),
_