From 710585d4922fd315f2cada8fbe550ae8ed23e994 Mon Sep 17 00:00:00 2001 From: Nicolas Dichtel Date: Wed, 10 Dec 2014 15:45:01 -0800 Subject: [PATCH] fs/proc: use a rb tree for the directory entries When a lot of netdevices are created, one of the bottleneck is the creation of proc entries. This serie aims to accelerate this part. The current implementation for the directories in /proc is using a single linked list. This is slow when handling directories with large numbers of entries (eg netdevice-related entries when lots of tunnels are opened). This patch replaces this linked list by a red-black tree. Here are some numbers: dummy30000.batch contains 30 000 times 'link add type dummy'. Before the patch: $ time ip -b dummy30000.batch real 2m31.950s user 0m0.440s sys 2m21.440s $ time rmmod dummy real 1m35.764s user 0m0.000s sys 1m24.088s After the patch: $ time ip -b dummy30000.batch real 2m0.874s user 0m0.448s sys 1m49.720s $ time rmmod dummy real 1m13.988s user 0m0.000s sys 1m1.008s The idea of improving this part was suggested by Thierry Herbelot. [akpm@linux-foundation.org: initialise proc_root.subdir at compile time] Signed-off-by: Nicolas Dichtel Acked-by: David S. Miller Cc: Thierry Herbelot . Acked-by: "Eric W. Biederman" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/proc/generic.c | 164 +++++++++++++++++++++++++++++---------------- fs/proc/internal.h | 11 +-- fs/proc/proc_net.c | 1 + fs/proc/root.c | 1 + 4 files changed, 113 insertions(+), 64 deletions(-) diff --git a/fs/proc/generic.c b/fs/proc/generic.c index 317b72641ebf..9f8fa1e5e8aa 100644 --- a/fs/proc/generic.c +++ b/fs/proc/generic.c @@ -31,9 +31,81 @@ static DEFINE_SPINLOCK(proc_subdir_lock); static int proc_match(unsigned int len, const char *name, struct proc_dir_entry *de) { - if (de->namelen != len) - return 0; - return !memcmp(name, de->name, len); + if (len < de->namelen) + return -1; + if (len > de->namelen) + return 1; + + return memcmp(name, de->name, len); +} + +static struct proc_dir_entry *pde_subdir_first(struct proc_dir_entry *dir) +{ + struct rb_node *node = rb_first(&dir->subdir); + + if (node == NULL) + return NULL; + + return rb_entry(node, struct proc_dir_entry, subdir_node); +} + +static struct proc_dir_entry *pde_subdir_next(struct proc_dir_entry *dir) +{ + struct rb_node *node = rb_next(&dir->subdir_node); + + if (node == NULL) + return NULL; + + return rb_entry(node, struct proc_dir_entry, subdir_node); +} + +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; + + while (node) { + struct proc_dir_entry *de = container_of(node, + struct proc_dir_entry, + subdir_node); + int result = proc_match(len, name, de); + + if (result < 0) + node = node->rb_left; + else if (result > 0) + node = node->rb_right; + else + return de; + } + return NULL; +} + +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; + + /* Figure out where to put new node */ + while (*new) { + struct proc_dir_entry *this = + container_of(*new, struct proc_dir_entry, subdir_node); + int result = proc_match(de->namelen, de->name, this); + + parent = *new; + if (result < 0) + new = &(*new)->rb_left; + else if (result > 0) + new = &(*new)->rb_right; + else + return false; + } + + /* Add new node and rebalance tree. */ + rb_link_node(&de->subdir_node, parent, new); + rb_insert_color(&de->subdir_node, root); + return true; } static int proc_notify_change(struct dentry *dentry, struct iattr *iattr) @@ -92,10 +164,7 @@ static int __xlate_proc_name(const char *name, struct proc_dir_entry **ret, break; len = next - cp; - for (de = de->subdir; de ; de = de->next) { - if (proc_match(len, cp, de)) - break; - } + de = pde_subdir_find(de, cp, len); if (!de) { WARN(1, "name '%s'\n", name); return -ENOENT; @@ -183,19 +252,16 @@ struct dentry *proc_lookup_de(struct proc_dir_entry *de, struct inode *dir, struct inode *inode; spin_lock(&proc_subdir_lock); - for (de = de->subdir; de ; de = de->next) { - if (de->namelen != dentry->d_name.len) - continue; - if (!memcmp(dentry->d_name.name, de->name, de->namelen)) { - pde_get(de); - spin_unlock(&proc_subdir_lock); - inode = proc_get_inode(dir->i_sb, de); - if (!inode) - return ERR_PTR(-ENOMEM); - d_set_d_op(dentry, &simple_dentry_operations); - d_add(dentry, inode); - return NULL; - } + de = pde_subdir_find(de, dentry->d_name.name, dentry->d_name.len); + if (de) { + pde_get(de); + spin_unlock(&proc_subdir_lock); + inode = proc_get_inode(dir->i_sb, de); + if (!inode) + return ERR_PTR(-ENOMEM); + d_set_d_op(dentry, &simple_dentry_operations); + d_add(dentry, inode); + return NULL; } spin_unlock(&proc_subdir_lock); return ERR_PTR(-ENOENT); @@ -225,7 +291,7 @@ int proc_readdir_de(struct proc_dir_entry *de, struct file *file, return 0; spin_lock(&proc_subdir_lock); - de = de->subdir; + de = pde_subdir_first(de); i = ctx->pos - 2; for (;;) { if (!de) { @@ -234,7 +300,7 @@ int proc_readdir_de(struct proc_dir_entry *de, struct file *file, } if (!i) break; - de = de->next; + de = pde_subdir_next(de); i--; } @@ -249,7 +315,7 @@ int proc_readdir_de(struct proc_dir_entry *de, struct file *file, } spin_lock(&proc_subdir_lock); ctx->pos++; - next = de->next; + next = pde_subdir_next(de); pde_put(de); de = next; } while (de); @@ -286,9 +352,8 @@ static const struct inode_operations proc_dir_inode_operations = { static int proc_register(struct proc_dir_entry * dir, struct proc_dir_entry * dp) { - struct proc_dir_entry *tmp; int ret; - + ret = proc_alloc_inum(&dp->low_ino); if (ret) return ret; @@ -308,17 +373,10 @@ static int proc_register(struct proc_dir_entry * dir, struct proc_dir_entry * dp } spin_lock(&proc_subdir_lock); - - for (tmp = dir->subdir; tmp; tmp = tmp->next) - if (strcmp(tmp->name, dp->name) == 0) { - WARN(1, "proc_dir_entry '%s/%s' already registered\n", - dir->name, dp->name); - break; - } - - dp->next = dir->subdir; dp->parent = dir; - dir->subdir = dp; + if (pde_subdir_insert(dir, dp) == false) + WARN(1, "proc_dir_entry '%s/%s' already registered\n", + dir->name, dp->name); spin_unlock(&proc_subdir_lock); return 0; @@ -354,6 +412,7 @@ 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; atomic_set(&ent->count, 1); spin_lock_init(&ent->pde_unload_lock); INIT_LIST_HEAD(&ent->pde_openers); @@ -485,7 +544,6 @@ void pde_put(struct proc_dir_entry *pde) */ void remove_proc_entry(const char *name, struct proc_dir_entry *parent) { - struct proc_dir_entry **p; struct proc_dir_entry *de = NULL; const char *fn = name; unsigned int len; @@ -497,14 +555,9 @@ void remove_proc_entry(const char *name, struct proc_dir_entry *parent) } len = strlen(fn); - for (p = &parent->subdir; *p; p=&(*p)->next ) { - if (proc_match(len, fn, *p)) { - de = *p; - *p = de->next; - de->next = NULL; - break; - } - } + de = pde_subdir_find(parent, fn, len); + if (de) + rb_erase(&de->subdir_node, &parent->subdir); spin_unlock(&proc_subdir_lock); if (!de) { WARN(1, "name '%s'\n", name); @@ -516,16 +569,15 @@ void remove_proc_entry(const char *name, struct proc_dir_entry *parent) if (S_ISDIR(de->mode)) parent->nlink--; de->nlink = 0; - WARN(de->subdir, "%s: removing non-empty directory " - "'%s/%s', leaking at least '%s'\n", __func__, - de->parent->name, de->name, de->subdir->name); + WARN(pde_subdir_first(de), + "%s: removing non-empty directory '%s/%s', leaking at least '%s'\n", + __func__, de->parent->name, de->name, pde_subdir_first(de)->name); pde_put(de); } EXPORT_SYMBOL(remove_proc_entry); int remove_proc_subtree(const char *name, struct proc_dir_entry *parent) { - struct proc_dir_entry **p; struct proc_dir_entry *root = NULL, *de, *next; const char *fn = name; unsigned int len; @@ -537,24 +589,18 @@ int remove_proc_subtree(const char *name, struct proc_dir_entry *parent) } len = strlen(fn); - for (p = &parent->subdir; *p; p=&(*p)->next ) { - if (proc_match(len, fn, *p)) { - root = *p; - *p = root->next; - root->next = NULL; - break; - } - } + root = pde_subdir_find(parent, fn, len); if (!root) { spin_unlock(&proc_subdir_lock); return -ENOENT; } + rb_erase(&root->subdir_node, &parent->subdir); + de = root; while (1) { - next = de->subdir; + next = pde_subdir_first(de); if (next) { - de->subdir = next->next; - next->next = NULL; + rb_erase(&next->subdir_node, &de->subdir); de = next; continue; } diff --git a/fs/proc/internal.h b/fs/proc/internal.h index aa7a0ee182e1..7fb1a4869fd0 100644 --- a/fs/proc/internal.h +++ b/fs/proc/internal.h @@ -24,10 +24,9 @@ struct mempolicy; * tree) of these proc_dir_entries, so that we can dynamically * add new files to /proc. * - * The "next" pointer creates a linked list of one /proc directory, - * while parent/subdir create the directory structure (every - * /proc file has a parent, but "subdir" is NULL for all - * non-directory entries). + * parent/subdir are used for the directory structure (every /proc file has a + * parent, but "subdir" is empty for all non-directory entries). + * subdir_node is used to build the rb tree "subdir" of the parent. */ struct proc_dir_entry { unsigned int low_ino; @@ -38,7 +37,9 @@ struct proc_dir_entry { loff_t size; const struct inode_operations *proc_iops; const struct file_operations *proc_fops; - struct proc_dir_entry *next, *parent, *subdir; + struct proc_dir_entry *parent; + struct rb_root subdir; + struct rb_node subdir_node; void *data; atomic_t count; /* use count */ atomic_t in_use; /* number of callers into module in progress; */ diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c index a63af3e0a612..1bde894bc624 100644 --- a/fs/proc/proc_net.c +++ b/fs/proc/proc_net.c @@ -192,6 +192,7 @@ static __net_init int proc_net_ns_init(struct net *net) if (!netd) goto out; + netd->subdir = RB_ROOT; netd->data = net; netd->nlink = 2; netd->namelen = 3; diff --git a/fs/proc/root.c b/fs/proc/root.c index 094e44d4a6be..e74ac9f1a2c0 100644 --- a/fs/proc/root.c +++ b/fs/proc/root.c @@ -251,6 +251,7 @@ struct proc_dir_entry proc_root = { .proc_iops = &proc_root_inode_operations, .proc_fops = &proc_root_operations, .parent = &proc_root, + .subdir = RB_ROOT, .name = "/proc", }; -- 2.20.1