From: Alexey Dobriyan <adobriyan@xxxxxxxxx> Subject: 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@xxxxxxxxx> Acked-by: Davidlohr Bueso <dbueso@xxxxxxx> Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/proc/generic.c | 26 ++++++++++++-------------- fs/proc/internal.h | 6 +++--- fs/proc/proc_net.c | 2 +- fs/proc/root.c | 2 +- 4 files changed, 17 insertions(+), 19 deletions(-) diff -puN fs/proc/generic.c~proc-use-slower-rb_first fs/proc/generic.c --- a/fs/proc/generic.c~proc-use-slower-rb_first +++ a/fs/proc/generic.c @@ -52,8 +52,8 @@ static int proc_match(const char *name, 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 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 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 pro 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_cre 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, 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 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; } diff -puN fs/proc/internal.h~proc-use-slower-rb_first fs/proc/internal.h --- a/fs/proc/internal.h~proc-use-slower-rb_first +++ a/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; diff -puN fs/proc/proc_net.c~proc-use-slower-rb_first fs/proc/proc_net.c --- a/fs/proc/proc_net.c~proc-use-slower-rb_first +++ a/fs/proc/proc_net.c @@ -196,7 +196,7 @@ static __net_init int proc_net_ns_init(s if (!netd) goto out; - netd->subdir = RB_ROOT_CACHED; + netd->subdir = RB_ROOT; netd->data = net; netd->nlink = 2; netd->namelen = 3; diff -puN fs/proc/root.c~proc-use-slower-rb_first fs/proc/root.c --- a/fs/proc/root.c~proc-use-slower-rb_first +++ a/fs/proc/root.c @@ -203,7 +203,7 @@ struct proc_dir_entry proc_root = { .proc_iops = &proc_root_inode_operations, .proc_fops = &proc_root_operations, .parent = &proc_root, - .subdir = RB_ROOT_CACHED, + .subdir = RB_ROOT, .name = proc_root.inline_name, .inline_name = "/proc", }; _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
