proc: use slower rb_first()

In a typical for /proc "open+read+close" usecase, dentry is looked up
successfully on open only to be killed in dput() on close.  In fact
dentries which aren't /proc/*/...  and /proc/sys/* were almost NEVER
CACHED.  Simple printk in proc_lookup_de() shows that.

Now that ->delete hook intelligently picks which dentries should live in
dcache and which should not, rbtree caching is not necessary as dcache
does it job, at last!

As a side effect, struct proc_dir_entry shrinks by one pointer which can
go into inline name.

Link: http://lkml.kernel.org/r/20180314231032.GA15854@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Acked-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Al Viro <viro@zeniv.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, 3 deletions

diff --git a/fs/proc/internal.h b/fs/proc/internal.h
index b7024f174778..0f1692e63cb6 100644
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -51,15 +51,15 @@ struct proc_dir_entry {
         kgid_t gid;
         loff_t size;
         struct proc_dir_entry *parent;
-        struct rb_root_cached subdir;
+        struct rb_root subdir;
         struct rb_node subdir_node;
         char *name;
         umode_t mode;
         u8 namelen;
 #ifdef CONFIG_64BIT
-#define SIZEOF_PDE_INLINE_NAME  (192-147)
+#define SIZEOF_PDE_INLINE_NAME  (192-139)
 #else
-#define SIZEOF_PDE_INLINE_NAME  (128-91)
+#define SIZEOF_PDE_INLINE_NAME  (128-87)
 #endif
         char inline_name[SIZEOF_PDE_INLINE_NAME];
 } __randomize_layout;