... such that we can avoid the tree walks to get the node with the smallest key. Semantically the same, as the previously used rb_first(), but O(1). The main overhead is the extra footprint for the cached rb_node pointer, which should not matter for procfs.
Acked-by: Peter Zijlstra (Intel) <[email protected]> Signed-off-by: Davidlohr Bueso <[email protected]> --- fs/proc/generic.c | 26 ++++++++++++++------------ fs/proc/internal.h | 2 +- fs/proc/proc_net.c | 2 +- fs/proc/root.c | 2 +- 4 files changed, 17 insertions(+), 15 deletions(-) diff --git a/fs/proc/generic.c b/fs/proc/generic.c index e3cda0b5968f..ab6496356dc2 100644 --- a/fs/proc/generic.c +++ b/fs/proc/generic.c @@ -40,8 +40,8 @@ static int proc_match(unsigned int len, const char *name, struct proc_dir_entry static struct proc_dir_entry *pde_subdir_first(struct proc_dir_entry *dir) { - return rb_entry_safe(rb_first(&dir->subdir), struct proc_dir_entry, - subdir_node); + return rb_entry_safe(rb_first_cached(&dir->subdir), + struct proc_dir_entry, subdir_node); } static struct proc_dir_entry *pde_subdir_next(struct proc_dir_entry *dir) @@ -54,7 +54,7 @@ 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_node; + struct rb_node *node = dir->subdir.rb_root.rb_node; while (node) { struct proc_dir_entry *de = rb_entry(node, @@ -75,8 +75,9 @@ 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 *root = &dir->subdir; - struct rb_node **new = &root->rb_node, *parent = NULL; + struct rb_root_cached *root = &dir->subdir; + struct rb_node **new = &root->rb_root.rb_node, *parent = NULL; + bool leftmost = true; /* Figure out where to put new node */ while (*new) { @@ -88,15 +89,16 @@ 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; - else + leftmost = false; + } else return false; } /* Add new node and rebalance tree. */ rb_link_node(&de->subdir_node, parent, new); - rb_insert_color(&de->subdir_node, root); + rb_insert_color_cached(&de->subdir_node, root, leftmost); return true; } @@ -369,7 +371,7 @@ 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; + ent->subdir = RB_ROOT_CACHED; atomic_set(&ent->count, 1); spin_lock_init(&ent->pde_unload_lock); INIT_LIST_HEAD(&ent->pde_openers); @@ -545,7 +547,7 @@ void remove_proc_entry(const char *name, struct proc_dir_entry *parent) de = pde_subdir_find(parent, fn, len); if (de) - rb_erase(&de->subdir_node, &parent->subdir); + rb_erase_cached(&de->subdir_node, &parent->subdir); write_unlock(&proc_subdir_lock); if (!de) { WARN(1, "name '%s'\n", name); @@ -582,13 +584,13 @@ int remove_proc_subtree(const char *name, struct proc_dir_entry *parent) write_unlock(&proc_subdir_lock); return -ENOENT; } - rb_erase(&root->subdir_node, &parent->subdir); + rb_erase_cached(&root->subdir_node, &parent->subdir); de = root; while (1) { next = pde_subdir_first(de); if (next) { - rb_erase(&next->subdir_node, &de->subdir); + rb_erase_cached(&next->subdir_node, &de->subdir); de = next; continue; } diff --git a/fs/proc/internal.h b/fs/proc/internal.h index aa2b89071630..8382d08385a9 100644 --- a/fs/proc/internal.h +++ b/fs/proc/internal.h @@ -40,7 +40,7 @@ struct proc_dir_entry { const struct inode_operations *proc_iops; const struct file_operations *proc_fops; struct proc_dir_entry *parent; - struct rb_root subdir; + struct rb_root_cached subdir; struct rb_node subdir_node; void *data; atomic_t count; /* use count */ diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c index d72fc40241d9..a2bf369c923d 100644 --- a/fs/proc/proc_net.c +++ b/fs/proc/proc_net.c @@ -196,7 +196,7 @@ static __net_init int proc_net_ns_init(struct net *net) if (!netd) goto out; - netd->subdir = RB_ROOT; + netd->subdir = RB_ROOT_CACHED; netd->data = net; netd->nlink = 2; netd->namelen = 3; diff --git a/fs/proc/root.c b/fs/proc/root.c index deecb397daa3..926fb27f4ca2 100644 --- a/fs/proc/root.c +++ b/fs/proc/root.c @@ -210,7 +210,7 @@ struct proc_dir_entry proc_root = { .proc_iops = &proc_root_inode_operations, .proc_fops = &proc_root_operations, .parent = &proc_root, - .subdir = RB_ROOT, + .subdir = RB_ROOT_CACHED, .name = "/proc", }; -- 2.12.0
