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>
diff --git a/fs/proc/generic.c b/fs/proc/generic.c
index fc0333f..04c4804 100644
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -52,8 +52,8 @@ static int proc_match(const char *name, struct proc_dir_entry *de, unsigned int
static struct proc_dir_entry *pde_subdir_first(struct proc_dir_entry *dir)
{
- return rb_entry_safe(rb_first_cached(&dir->subdir),
- struct proc_dir_entry, subdir_node);
+ return rb_entry_safe(rb_first(&dir->subdir), struct proc_dir_entry,
+ subdir_node);
}
static struct proc_dir_entry *pde_subdir_next(struct proc_dir_entry *dir)
@@ -66,7 +66,7 @@ static struct proc_dir_entry *pde_subdir_find(struct proc_dir_entry *dir,
const char *name,
unsigned int len)
{
- struct rb_node *node = dir->subdir.rb_root.rb_node;
+ struct rb_node *node = dir->subdir.rb_node;
while (node) {
struct proc_dir_entry *de = rb_entry(node,
@@ -87,9 +87,8 @@ static struct proc_dir_entry *pde_subdir_find(struct proc_dir_entry *dir,
static bool pde_subdir_insert(struct proc_dir_entry *dir,
struct proc_dir_entry *de)
{
- struct rb_root_cached *root = &dir->subdir;
- struct rb_node **new = &root->rb_root.rb_node, *parent = NULL;
- bool leftmost = true;
+ struct rb_root *root = &dir->subdir;
+ struct rb_node **new = &root->rb_node, *parent = NULL;
/* Figure out where to put new node */
while (*new) {
@@ -101,16 +100,15 @@ static bool pde_subdir_insert(struct proc_dir_entry *dir,
parent = *new;
if (result < 0)
new = &(*new)->rb_left;
- else if (result > 0) {
+ else if (result > 0)
new = &(*new)->rb_right;
- leftmost = false;
- } else
+ else
return false;
}
/* Add new node and rebalance tree. */
rb_link_node(&de->subdir_node, parent, new);
- rb_insert_color_cached(&de->subdir_node, root, leftmost);
+ rb_insert_color(&de->subdir_node, root);
return true;
}
@@ -401,7 +399,7 @@ static struct proc_dir_entry *__proc_create(struct proc_dir_entry **parent,
ent->namelen = qstr.len;
ent->mode = mode;
ent->nlink = nlink;
- ent->subdir = RB_ROOT_CACHED;
+ ent->subdir = RB_ROOT;
refcount_set(&ent->refcnt, 1);
spin_lock_init(&ent->pde_unload_lock);
INIT_LIST_HEAD(&ent->pde_openers);
@@ -577,7 +575,7 @@ void remove_proc_entry(const char *name, struct proc_dir_entry *parent)
de = pde_subdir_find(parent, fn, len);
if (de)
- rb_erase_cached(&de->subdir_node, &parent->subdir);
+ rb_erase(&de->subdir_node, &parent->subdir);
write_unlock(&proc_subdir_lock);
if (!de) {
WARN(1, "name '%s'\n", name);
@@ -614,13 +612,13 @@ int remove_proc_subtree(const char *name, struct proc_dir_entry *parent)
write_unlock(&proc_subdir_lock);
return -ENOENT;
}
- rb_erase_cached(&root->subdir_node, &parent->subdir);
+ rb_erase(&root->subdir_node, &parent->subdir);
de = root;
while (1) {
next = pde_subdir_first(de);
if (next) {
- rb_erase_cached(&next->subdir_node, &de->subdir);
+ rb_erase(&next->subdir_node, &de->subdir);
de = next;
continue;
}