[PATCH] sysctl: reimplement the sysctl proc support

With this change the sysctl inodes can be cached and nothing needs to be done
when removing a sysctl table.

For a cost of 2K code we will save about 4K of static tables (when we remove
de from ctl_table) and 70K in proc_dir_entries that we will not allocate, or
about half that on a 32bit arch.

The speed feels about the same, even though we can now cache the sysctl
dentries :(

We get the core advantage that we don't need to have a 1 to 1 mapping between
ctl table entries and proc files.  Making it possible to have /proc/sys vary
depending on the namespace you are in.  The currently merged namespaces don't
have an issue here but the network namespace under /proc/sys/net needs to have
different directories depending on which network adapters are visible.  By
simply being a cache different directories being visible depending on who you
are is trivial to implement.

[akpm@osdl.org: fix uninitialised var]
[akpm@osdl.org: fix ARM build]
[bunk@stusta.de: make things static]
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 7 deletions

diff --git a/fs/proc/root.c b/fs/proc/root.c
index 6ae222b509ce..5834a744c2a9 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -23,10 +23,6 @@
 
 struct proc_dir_entry *proc_net, *proc_net_stat, *proc_bus, *proc_root_fs, *proc_root_driver;
 
-#ifdef CONFIG_SYSCTL
-struct proc_dir_entry *proc_sys_root;
-#endif
-
 static int proc_get_sb(struct file_system_type *fs_type,
         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
 {
@@ -71,9 +67,6 @@ void __init proc_root_init(void)
 #ifdef CONFIG_SYSVIPC
         proc_mkdir("sysvipc", NULL);
 #endif
-#ifdef CONFIG_SYSCTL
-        proc_sys_root = proc_mkdir("sys", NULL);
-#endif
         proc_root_fs = proc_mkdir("fs", NULL);
         proc_root_driver = proc_mkdir("driver", NULL);
         proc_mkdir("fs/nfsd", NULL); /* somewhere for the nfsd filesystem to be mounted */
@@ -86,6 +79,9 @@ void __init proc_root_init(void)
         proc_device_tree_init();
 #endif
         proc_bus = proc_mkdir("bus", NULL);
+#ifdef CONFIG_SYSCTL
+        proc_sys_init();
+#endif
 }
 
 static int proc_root_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat