diff options
Diffstat (limited to 'kernel/cgroup.c')
| -rw-r--r-- | kernel/cgroup.c | 1115 |
1 files changed, 362 insertions, 753 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index d8efca44de5f..cda614da40cf 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -40,9 +40,7 @@ #include <linux/proc_fs.h> #include <linux/rcupdate.h> #include <linux/sched.h> -#include <linux/backing-dev.h> #include <linux/slab.h> -#include <linux/magic.h> #include <linux/spinlock.h> #include <linux/string.h> #include <linux/sort.h> @@ -50,7 +48,6 @@ #include <linux/delayacct.h> #include <linux/cgroupstats.h> #include <linux/hashtable.h> -#include <linux/namei.h> #include <linux/pid_namespace.h> #include <linux/idr.h> #include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */ @@ -176,7 +173,6 @@ static void cgroup_destroy_css_killed(struct cgroup *cgrp); static int cgroup_destroy_locked(struct cgroup *cgrp); static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[], bool is_add); -static int cgroup_file_release(struct inode *inode, struct file *file); static void cgroup_pidlist_destroy_all(struct cgroup *cgrp); /** @@ -209,8 +205,22 @@ static inline bool cgroup_is_dead(const struct cgroup *cgrp) struct cgroup_subsys_state *seq_css(struct seq_file *seq) { - struct cgroup_open_file *of = seq->private; - return of->cfe->css; + struct kernfs_open_file *of = seq->private; + struct cgroup *cgrp = of->kn->parent->priv; + struct cftype *cft = seq_cft(seq); + + /* + * This is open and unprotected implementation of cgroup_css(). + * seq_css() is only called from a kernfs file operation which has + * an active reference on the file. Because all the subsystem + * files are drained before a css is disassociated with a cgroup, + * the matching css from the cgroup's subsys table is guaranteed to + * be and stay valid until the enclosing operation is complete. + */ + if (cft->ss) + return rcu_dereference_raw(cgrp->subsys[cft->ss->id]); + else + return &cgrp->dummy_css; } EXPORT_SYMBOL_GPL(seq_css); @@ -276,21 +286,6 @@ static int notify_on_release(const struct cgroup *cgrp) #define for_each_active_root(root) \ list_for_each_entry((root), &cgroup_roots, root_list) -static inline struct cgroup *__d_cgrp(struct dentry *dentry) -{ - return dentry->d_fsdata; -} - -static inline struct cfent *__d_cfe(struct dentry *dentry) -{ - return dentry->d_fsdata; -} - -static inline struct cftype *__d_cft(struct dentry *dentry) -{ - return __d_cfe(dentry)->type; -} - /** * cgroup_lock_live_group - take cgroup_mutex and check that cgrp is alive. * @cgrp: the cgroup to be checked for liveness @@ -692,6 +687,13 @@ static struct css_set *find_css_set(struct css_set *old_cset, return cset; } +static struct cgroupfs_root *cgroup_root_from_kf(struct kernfs_root *kf_root) +{ + struct cgroup *top_cgrp = kf_root->kn->priv; + + return top_cgrp->root; +} + static int cgroup_init_root_id(struct cgroupfs_root *root, int start, int end) { int id; @@ -730,30 +732,37 @@ static void cgroup_free_root(struct cgroupfs_root *root) static void cgroup_get_root(struct cgroupfs_root *root) { - atomic_inc(&root->sb->s_active); + /* + * The caller must ensure that @root is alive, which can be + * achieved by holding a ref on one of the member cgroups or + * following a registered reference to @root while holding + * cgroup_tree_mutex. + */ + WARN_ON_ONCE(atomic_read(&root->refcnt) <= 0); + atomic_inc(&root->refcnt); } static void cgroup_put_root(struct cgroupfs_root *root) { - deactivate_super(root->sb); -} - -static void cgroup_kill_sb(struct super_block *sb) -{ - struct cgroupfs_root *root = sb->s_fs_info; struct cgroup *cgrp = &root->top_cgroup; struct cgrp_cset_link *link, *tmp_link; int ret; - BUG_ON(!root); + /* + * @root's refcnt reaching zero and its deregistration should be + * atomic w.r.t. cgroup_tree_mutex. This ensures that + * cgroup_get_root() is safe to invoke if @root is registered. + */ + mutex_lock(&cgroup_tree_mutex); + if (!atomic_dec_and_test(&root->refcnt)) { + mutex_unlock(&cgroup_tree_mutex); + return; + } + mutex_lock(&cgroup_mutex); BUG_ON(root->number_of_cgroups != 1); BUG_ON(!list_empty(&cgrp->children)); - mutex_lock(&cgrp->dentry->d_inode->i_mutex); - mutex_lock(&cgroup_tree_mutex); - mutex_lock(&cgroup_mutex); - /* Rebind all subsystems back to the default hierarchy */ if (root->flags & CGRP_ROOT_SUBSYS_BOUND) { ret = rebind_subsystems(root, 0, root->subsys_mask); @@ -783,11 +792,8 @@ static void cgroup_kill_sb(struct super_block *sb) mutex_unlock(&cgroup_mutex); mutex_unlock(&cgroup_tree_mutex); - mutex_unlock(&cgrp->dentry->d_inode->i_mutex); - - simple_xattrs_free(&cgrp->xattrs); - kill_litter_super(sb); + kernfs_destroy_root(root->kf_root); cgroup_free_root(root); } @@ -878,42 +884,10 @@ static struct cgroup *task_cgroup_from_root(struct task_struct *task, * update of a tasks cgroup pointer by cgroup_attach_task() */ -/* - * A couple of forward declarations required, due to cyclic reference loop: - * cgroup_mkdir -> cgroup_create -> cgroup_populate_dir -> - * cgroup_add_file -> cgroup_create_file -> cgroup_dir_inode_operations - * -> cgroup_mkdir. - */ - -static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode); -static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry); static int cgroup_populate_dir(struct cgroup *cgrp, unsigned long subsys_mask); -static const struct inode_operations cgroup_dir_inode_operations; +static struct kernfs_syscall_ops cgroup_kf_syscall_ops; static const struct file_operations proc_cgroupstats_operations; -static struct backing_dev_info cgroup_backing_dev_info = { - .name = "cgroup", - .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, -}; - -static struct inode *cgroup_new_inode(umode_t mode, struct super_block *sb) -{ - struct inode *inode = new_inode(sb); - - if (inode) { - do { - /* ino 0 is reserved for dummy_root */ - inode->i_ino = get_next_ino(); - } while (!inode->i_ino); - inode->i_mode = mode; - inode->i_uid = current_fsuid(); - inode->i_gid = current_fsgid(); - inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; - inode->i_mapping->backing_dev_info = &cgroup_backing_dev_info; - } - return inode; -} - static struct cgroup_name *cgroup_alloc_name(const char *name_str) { struct cgroup_name *name; @@ -983,8 +957,6 @@ static void cgroup_free_fn(struct work_struct *work) cgroup_pidlist_destroy_all(cgrp); - simple_xattrs_free(&cgrp->xattrs); - kfree(rcu_dereference_raw(cgrp->name)); kfree(cgrp); } @@ -999,81 +971,38 @@ static void cgroup_free_rcu(struct rcu_head *head) static void cgroup_get(struct cgroup *cgrp) { - dget(cgrp->dentry); -} - -static void cgroup_diput(struct dentry *dentry, struct inode *inode) -{ - /* is dentry a directory ? if so, kfree() associated cgroup */ - if (S_ISDIR(inode->i_mode)) { - struct cgroup *cgrp = dentry->d_fsdata; - - BUG_ON(!(cgroup_is_dead(cgrp))); - - /* - * XXX: cgrp->id is only used to look up css's. As cgroup - * and css's lifetimes will be decoupled, it should be made - * per-subsystem and moved to css->id so that lookups are - * successful until the target css is released. - */ - mutex_lock(&cgroup_mutex); - idr_remove(&cgrp->root->cgroup_idr, cgrp->id); - mutex_unlock(&cgroup_mutex); - cgrp->id = -1; - - call_rcu(&cgrp->rcu_head, cgroup_free_rcu); - } else { - struct cfent *cfe = __d_cfe(dentry); - struct cgroup *cgrp = dentry->d_parent->d_fsdata; - - WARN_ONCE(!list_empty(&cfe->node) && - cgrp != &cgrp->root->top_cgroup, - "cfe still linked for %s\n", cfe->type->name); - simple_xattrs_free(&cfe->xattrs); - kfree(cfe); - } - iput(inode); + WARN_ON_ONCE(cgroup_is_dead(cgrp)); + WARN_ON_ONCE(atomic_read(&cgrp->refcnt) <= 0); + atomic_inc(&cgrp->refcnt); } static void cgroup_put(struct cgroup *cgrp) { - dput(cgrp->dentry); -} + if (!atomic_dec_and_test(&cgrp->refcnt)) + return; + if (WARN_ON_ONCE(!cgroup_is_dead(cgrp))) + return; -static void remove_dir(struct dentry *d) -{ - struct dentry *parent = dget(d->d_parent); + /* + * XXX: cgrp->id is only used to look up css's. As cgroup and + * css's lifetimes will be decoupled, it should be made + * per-subsystem and moved to css->id so that lookups are + * successful until the target css is released. + */ + mutex_lock(&cgroup_mutex); + idr_remove(&cgrp->root->cgroup_idr, cgrp->id); + mutex_unlock(&cgroup_mutex); + cgrp->id = -1; - d_delete(d); - simple_rmdir(parent->d_inode, d); - dput(parent); + call_rcu(&cgrp->rcu_head, cgroup_free_rcu); } static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft) { - struct cfent *cfe; + char name[CGROUP_FILE_NAME_MAX]; - lockdep_assert_held(&cgrp->dentry->d_inode->i_mutex); lockdep_assert_held(&cgroup_tree_mutex); - - /* - * If we're doing cleanup due to failure of cgroup_create(), - * the corresponding @cfe may not exist. - */ - list_for_each_entry(cfe, &cgrp->files, node) { - struct dentry *d = cfe->dentry; - - if (cft && cfe->type != cft) - continue; - - dget(d); - d_delete(d); - simple_unlink(cgrp->dentry->d_inode, d); - list_del_init(&cfe->node); - dput(d); - - break; - } + kernfs_remove_by_name(cgrp->kn, cgroup_file_name(cgrp, cft, name)); } /** @@ -1096,22 +1025,6 @@ static void cgroup_clear_dir(struct cgroup *cgrp, unsigned long subsys_mask) } } -/* - * NOTE : the dentry must have been dget()'ed - */ -static void cgroup_d_remove_dir(struct dentry *dentry) -{ - struct dentry *parent; - - parent = dentry->d_parent; - spin_lock(&parent->d_lock); - spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); - list_del_init(&dentry->d_u.d_child); - spin_unlock(&dentry->d_lock); - spin_unlock(&parent->d_lock); - remove_dir(dentry); -} - static int rebind_subsystems(struct cgroupfs_root *root, unsigned long added_mask, unsigned removed_mask) { @@ -1179,13 +1092,15 @@ static int rebind_subsystems(struct cgroupfs_root *root, * now matches the bound subsystems. */ root->flags |= CGRP_ROOT_SUBSYS_BOUND; + kernfs_activate(cgrp->kn); return 0; } -static int cgroup_show_options(struct seq_file *seq, struct dentry *dentry) +static int cgroup_show_options(struct seq_file *seq, + struct kernfs_root *kf_root) { - struct cgroupfs_root *root = dentry->d_sb->s_fs_info; + struct cgroupfs_root *root = cgroup_root_from_kf(kf_root); struct cgroup_subsys *ss; int ssid; @@ -1219,9 +1134,6 @@ struct cgroup_sb_opts { char *name; /* User explicitly requested empty subsystem */ bool none; - - struct cgroupfs_root *new_root; - }; /* @@ -1380,11 +1292,10 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) return 0; } -static int cgroup_remount(struct super_block *sb, int *flags, char *data) +static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data) { int ret = 0; - struct cgroupfs_root *root = sb->s_fs_info; - struct cgroup *cgrp = &root->top_cgroup; + struct cgroupfs_root *root = cgroup_root_from_kf(kf_root); struct cgroup_sb_opts opts; unsigned long added_mask, removed_mask; @@ -1393,7 +1304,6 @@ static int cgroup_remount(struct super_block *sb, int *flags, char *data) return -EINVAL; } - mutex_lock(&cgrp->dentry->d_inode->i_mutex); mutex_lock(&cgroup_tree_mutex); mutex_lock(&cgroup_mutex); @@ -1439,34 +1349,26 @@ static int cgroup_remount(struct super_block *sb, int *flags, char *data) kfree(opts.name); mutex_unlock(&cgroup_mutex); mutex_unlock(&cgroup_tree_mutex); - mutex_unlock(&cgrp->dentry->d_inode->i_mutex); return ret; } -static const struct super_operations cgroup_ops = { - .statfs = simple_statfs, - .drop_inode = generic_delete_inode, - .show_options = cgroup_show_options, - .remount_fs = cgroup_remount, -}; - static void init_cgroup_housekeeping(struct cgroup *cgrp) { + atomic_set(&cgrp->refcnt, 1); INIT_LIST_HEAD(&cgrp->sibling); INIT_LIST_HEAD(&cgrp->children); - INIT_LIST_HEAD(&cgrp->files); INIT_LIST_HEAD(&cgrp->cset_links); INIT_LIST_HEAD(&cgrp->release_list); INIT_LIST_HEAD(&cgrp->pidlists); mutex_init(&cgrp->pidlist_mutex); cgrp->dummy_css.cgroup = cgrp; - simple_xattrs_init(&cgrp->xattrs); } static void init_cgroup_root(struct cgroupfs_root *root) { struct cgroup *cgrp = &root->top_cgroup; + atomic_set(&root->refcnt, 1); INIT_LIST_HEAD(&root->root_list); root->number_of_cgroups = 1; cgrp->root = root; @@ -1475,32 +1377,12 @@ static void init_cgroup_root(struct cgroupfs_root *root) idr_init(&root->cgroup_idr); } -static int cgroup_test_super(struct super_block *sb, void *data) -{ - struct cgroup_sb_opts *opts = data; - struct cgroupfs_root *root = sb->s_fs_info; - - /* If we asked for a name then it must match */ - if (opts->name && strcmp(opts->name, root->name)) - return 0; - - /* - * If we asked for subsystems (or explicitly for no - * subsystems) then they must match - */ - if ((opts->subsys_mask || opts->none) - && (opts->subsys_mask != root->subsys_mask)) - return 0; - - return 1; -} - static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts) { struct cgroupfs_root *root; if (!opts->subsys_mask && !opts->none) - return NULL; + return ERR_PTR(-EINVAL); root = kzalloc(sizeof(*root), GFP_KERNEL); if (!root) @@ -1527,99 +1409,21 @@ static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts) return root; } -static int cgroup_set_super(struct super_block *sb, void *data) -{ - int ret; - struct cgroup_sb_opts *opts = data; - - /* If we don't have a new root, we can't set up a new sb */ - if (!opts->new_root) - return -EINVAL; - - BUG_ON(!opts->subsys_mask && !opts->none); - - ret = set_anon_super(sb, NULL); - if (ret) - return ret; - - sb->s_fs_info = opts->new_root; - opts->new_root->sb = sb; - - sb->s_blocksize = PAGE_CACHE_SIZE; - sb->s_blocksize_bits = PAGE_CACHE_SHIFT; - sb->s_magic = CGROUP_SUPER_MAGIC; - sb->s_op = &cgroup_ops; - - return 0; -} - -static int cgroup_get_rootdir(struct super_block *sb) -{ - static const struct dentry_operations cgroup_dops = { - .d_iput = cgroup_diput, - .d_delete = always_delete_dentry, - }; - - struct inode *inode = - cgroup_new_inode(S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR, sb); - - if (!inode) - return -ENOMEM; - - inode->i_fop = &simple_dir_operations; - inode->i_op = &cgroup_dir_inode_operations; - /* directories start off with i_nlink == 2 (for "." entry) */ - inc_nlink(inode); - sb->s_root = d_make_root(inode); - if (!sb->s_root) - return -ENOMEM; - /* for everything else we want ->d_op set */ - sb->s_d_op = &cgroup_dops; - return 0; -} - static int cgroup_setup_root(struct cgroupfs_root *root) { LIST_HEAD(tmp_links); - struct super_block *sb = root->sb; struct cgroup *root_cgrp = &root->top_cgroup; - struct cgroupfs_root *existing_root; struct css_set *cset; - struct inode *inode; - const struct cred *cred; int i, ret; lockdep_assert_held(&cgroup_tree_mutex); lockdep_assert_held(&cgroup_mutex); - BUG_ON(sb->s_root != NULL); - - mutex_unlock(&cgroup_mutex); - mutex_unlock(&cgroup_tree_mutex); - - ret = cgroup_get_rootdir(sb); - if (ret) { - mutex_lock(&cgroup_tree_mutex); - mutex_lock(&cgroup_mutex); - return ret; - } - inode = sb->s_root->d_inode; - - mutex_lock(&inode->i_mutex); - mutex_lock(&cgroup_tree_mutex); - mutex_lock(&cgroup_mutex); ret = idr_alloc(&root->cgroup_idr, root_cgrp, 0, 1, GFP_KERNEL); if (ret < 0) - goto out_unlock; + goto out; root_cgrp->id = ret; - /* check for name clashes with existing mounts */ - ret = -EBUSY; - if (strlen(root->name)) - for_each_active_root(existing_root) - if (!strcmp(existing_root->name, root->name)) - goto out_unlock; - /* * We're accessing css_set_count without locking css_set_lock here, * but that's OK - it can only be increased by someone holding @@ -1628,34 +1432,29 @@ static int cgroup_setup_root(struct cgroupfs_root *root) */ ret = allocate_cgrp_cset_links(css_set_count, &tmp_links); if (ret) - goto out_unlock; + goto out; /* ID 0 is reserved for dummy root, 1 for unified hierarchy */ ret = cgroup_init_root_id(root, 2, 0); if (ret) - goto out_unlock; - - sb->s_root->d_fsdata = root_cgrp; - root_cgrp->dentry = sb->s_root; + goto out; - /* - * We're inside get_sb() and will call lookup_one_len() to create - * the root files, which doesn't work if SELinux is in use. The - * following cred dancing somehow works around it. See 2ce9738ba - * ("cgroupfs: use init_cred when populating new cgroupfs mount") - * for more details. - */ - cred = override_creds(&init_cred); + root->kf_root = kernfs_create_root(&cgroup_kf_syscall_ops, + KERNFS_ROOT_CREATE_DEACTIVATED, + root_cgrp); + if (IS_ERR(root->kf_root)) { + ret = PTR_ERR(root->kf_root); + goto exit_root_id; + } + root_cgrp->kn = root->kf_root->kn; ret = cgroup_addrm_files(root_cgrp, cgroup_base_files, true); if (ret) - goto rm_base_files; + goto destroy_root; ret = rebind_subsystems(root, root->subsys_mask, 0); if (ret) - goto rm_base_files; - - revert_creds(cred); + goto destroy_root; /* * There must be no failure case after here, since rebinding takes @@ -1677,15 +1476,16 @@ static int cgroup_setup_root(struct cgroupfs_root *root) BUG_ON(!list_empty(&root_cgrp->children)); BUG_ON(root->number_of_cgroups != 1); + kernfs_activate(root_cgrp->kn); ret = 0; - goto out_unlock; + goto out; -rm_base_files: - cgroup_addrm_files(&root->top_cgroup, cgroup_base_files, false); - revert_creds(cred); +destroy_root: + kernfs_destroy_root(root->kf_root); + root->kf_root = NULL; +exit_root_id: cgroup_exit_root_id(root); -out_unlock: - mutex_unlock(&inode->i_mutex); +out: free_cgrp_cset_links(&tmp_links); return ret; } @@ -1694,10 +1494,9 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type, int flags, const char *unused_dev_name, void *data) { - struct super_block *sb = NULL; - struct cgroupfs_root *root = NULL; + struct cgroupfs_root *root; struct cgroup_sb_opts opts; - struct cgroupfs_root *new_root; + struct dentry *dentry; int ret; mutex_lock(&cgroup_tree_mutex); @@ -1708,41 +1507,32 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type, if (ret) goto out_unlock; - /* - * Allocate a new cgroup root. We may not need it if we're - * reusing an existing hierarchy. - */ - new_root = cgroup_root_from_opts(&opts); - if (IS_ERR(new_root)) { - ret = PTR_ERR(new_root); - goto out_unlock; - } - opts.new_root = new_root; + /* look for a matching existing root */ + for_each_active_root(root) { + bool name_match = false; - /* Locate an existing or new sb for this hierarchy */ - mutex_unlock(&cgroup_mutex); - mutex_unlock(&cgroup_tree_mutex); - sb = sget(fs_type, cgroup_test_super, cgroup_set_super, 0, &opts); - mutex_lock(&cgroup_tree_mutex); - mutex_lock(&cgroup_mutex); - if (IS_ERR(sb)) { - ret = PTR_ERR(sb); - cgroup_free_root(opts.new_root); - goto out_unlock; - } + /* + * If we asked for a name then it must match. Also, if + * name matches but sybsys_mask doesn't, we should fail. + * Remember whether name matched. + */ + if (opts.name) { + if (strcmp(opts.name, root->name)) + continue; + name_match = true; + } - root = sb->s_fs_info; - BUG_ON(!root); - if (root == opts.new_root) { - ret = cgroup_setup_root(root); - if (ret) - goto out_unlock; - } else { /* - * We re-used an existing hierarchy - the new root (if - * any) is not needed + * If we asked for subsystems (or explicitly for no + * subsystems) then they must match. */ - cgroup_free_root(opts.new_root); + if ((opts.subsys_mask || opts.none) && + (opts.subsys_mask != root->subsys_mask)) { + if (!name_match) + continue; + ret = -EBUSY; + goto out_unlock; + } if ((root->flags ^ opts.flags) & CGRP_ROOT_OPTION_MASK) { if ((root->flags | opts.flags) & CGRP_ROOT_SANE_BEHAVIOR) { @@ -1753,23 +1543,45 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type, pr_warning("cgroup: new mount options do not match the existing superblock, will be ignored\n"); } } + + cgroup_get_root(root); + goto out_unlock; } - ret = 0; + /* no such thing, create a new one */ + root = cgroup_root_from_opts(&opts); + if (IS_ERR(root)) { + ret = PTR_ERR(root); + goto out_unlock; + } + + ret = cgroup_setup_root(root); + if (ret) + cgroup_free_root(root); + out_unlock: mutex_unlock(&cgroup_mutex); mutex_unlock(&cgroup_tree_mutex); - if (ret && !IS_ERR_OR_NULL(sb)) - deactivate_locked_super(sb); - kfree(opts.release_agent); kfree(opts.name); - if (!ret) - return dget(sb->s_root); - else + if (ret) return ERR_PTR(ret); + + dentry = kernfs_mount(fs_type, flags, root->kf_root); + if (IS_ERR(dentry)) + cgroup_put_root(root); + return dentry; +} + +static void cgroup_kill_sb(struct super_block *sb) +{ + struct kernfs_root *kf_root = kernfs_root_from_sb(sb); + struct cgroupfs_root *root = cgroup_root_from_kf(kf_root); + + cgroup_put_root(root); + kernfs_kill_sb(sb); } static struct file_system_type cgroup_fs_type = { @@ -2301,29 +2113,23 @@ static int cgroup_sane_behavior_show(struct seq_file *seq, void *v) return 0; } -static ssize_t cgroup_file_write(struct file *file, const char __user *userbuf, - size_t nbytes, loff_t *ppos) +static ssize_t cgroup_file_write(struct kernfs_open_file *of, char *buf, + size_t nbytes, loff_t off) { - struct cfent *cfe = __d_cfe(file->f_dentry); - struct cftype *cft = __d_cft(file->f_dentry); - struct cgroup_subsys_state *css = cfe->css; - size_t max_bytes = max(cft->max_write_len, PAGE_SIZE); - char *buf; + struct cgroup *cgrp = of->kn->parent->priv; + struct cftype *cft = of->kn->priv; + struct cgroup_subsys_state *css; int ret; - if (nbytes > max_bytes) - return -E2BIG; - - buf = kmalloc(nbytes + 1, GFP_KERNEL); - if (!buf) - return -ENOMEM; - - if (copy_from_user(buf, userbuf, nbytes)) { - ret = -EFAULT; - goto out_free; - } - - buf[nbytes] = '\0'; + /* + * kernfs guarantees that a file isn't deleted with operations in + * flight, which means that the matching css is and stays alive and + * doesn't need to be pinned. The RCU locking is not necessary + * either. It's just for the convenience of using cgroup_css(). + */ + rcu_read_lock(); + css = cgroup_css(cgrp, cft->ss); + rcu_read_unlock(); if (cft->write_string) { ret = cft->write_string(css, cft, strstrip(buf)); @@ -2342,53 +2148,23 @@ static ssize_t cgroup_file_write(struct file *file, const char __user *userbuf, } else { ret = -EINVAL; } -out_free: - kfree(buf); + return ret ?: nbytes; } -/* - * seqfile ops/methods for returning structured data. Currently just - * supports string->u64 maps, but can be extended in future. - */ - static void *cgroup_seqfile_start(struct seq_file *seq, loff_t *ppos) { - struct cftype *cft = seq_cft(seq); - - if (cft->seq_start) { - return cft->seq_start(seq, ppos); - } else { - /* - * The same behavior and code as single_open(). Returns - * !NULL if pos is at the beginning; otherwise, NULL. - */ - return NULL + !*ppos; - } + return seq_cft(seq)->seq_start(seq, ppos); } static void *cgroup_seqfile_next(struct seq_file *seq, void *v, loff_t *ppos) { - struct cftype *cft = seq_cft(seq); - - if (cft->seq_next) { - return cft->seq_next(seq, v, ppos); - } else { - /* - * The same behavior and code as single_open(), always - * terminate after the initial read. - */ - ++*ppos; - return NULL; - } + return seq_cft(seq)->seq_next(seq, v, ppos); } static void cgroup_seqfile_stop(struct seq_file *seq, void *v) { - struct cftype *cft = seq_cft(seq); - - if (cft->seq_stop) - cft->seq_stop(seq, v); + seq_cft(seq)->seq_stop(seq, v); } static int cgroup_seqfile_show(struct seq_file *m, void *arg) @@ -2408,96 +2184,36 @@ static int cgroup_seqfile_show(struct seq_file *m, void *arg) return 0; } -static struct seq_operations cgroup_seq_operations = { - .start = cgroup_seqfile_start, - .next = cgroup_seqfile_next, - .stop = cgroup_seqfile_stop, - .show = cgroup_seqfile_show, +static struct kernfs_ops cgroup_kf_single_ops = { + .atomic_write_len = PAGE_SIZE, + .write = cgroup_file_write, + .seq_show = cgroup_seqfile_show, }; -static int cgroup_file_open(struct inode *inode, struct file *file) -{ - struct cfent *cfe = __d_cfe(file->f_dentry); - struct cftype *cft = __d_cft(file->f_dentry); - struct cgroup *cgrp = __d_cgrp(cfe->dentry->d_parent); - struct cgroup_subsys_state *css; - struct cgroup_open_file *of; - int err; - - err = generic_file_open(inode, file); - if (err) - return err; - - /* - * If the file belongs to a subsystem, pin the css. Will be - * unpinned either on open failure or release. This ensures that - * @css stays alive for all file operations. - */ - rcu_read_lock(); - css = cgroup_css(cgrp, cft->ss); - if (cft->ss && !css_tryget(css)) - css = NULL; - rcu_read_unlock(); - - if (!css) - return -ENODEV; - - /* - * @cfe->css is used by read/write/close to determine the - * associated css. @file->private_data would be a better place but - * that's already used by seqfile. Multiple accessors may use it - * simultaneously which is okay as the association never changes. - */ - WARN_ON_ONCE(cfe->css && cfe->css != css); - cfe->css = css; - - of = __seq_open_private(file, &cgroup_seq_operations, - sizeof(struct cgroup_open_file)); - if (of) { - of->cfe = cfe; - return 0; - } - - if (css->ss) - css_put(css); - return -ENOMEM; -} - -static int cgroup_file_release(struct inode *inode, struct file *file) -{ - struct cfent *cfe = __d_cfe(file->f_dentry); - struct cgroup_subsys_state *css = cfe->css; - - if (css->ss) - css_put(css); - return seq_release_private(inode, file); -} +static struct kernfs_ops cgroup_kf_ops = { + .atomic_write_len = PAGE_SIZE, + .write = cgroup_file_write, + .seq_start = cgroup_seqfile_start, + .seq_next = cgroup_seqfile_next, + .seq_stop = cgroup_seqfile_stop, + .seq_show = cgroup_seqfile_show, +}; /* * cgroup_rename - Only allow simple rename of directories in place. */ -static int cgroup_rename(struct inode *old_dir, struct dentry *old_dentry, - struct inode *new_dir, struct dentry *new_dentry) +static int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent, + const char *new_name_str) { - int ret; + struct cgroup *cgrp = kn->priv; struct cgroup_name *name, *old_name; - struct cgroup *cgrp; - - /* - * It's convinient to use parent dir's i_mutex to protected - * cgrp->name. - */ - lockdep_assert_held(&old_dir->i_mutex); + int ret; - if (!S_ISDIR(old_dentry->d_inode->i_mode)) + if (kernfs_type(kn) != KERNFS_DIR) return -ENOTDIR; - if (new_dentry->d_inode) - return -EEXIST; - if (old_dir != new_dir) + if (kn->parent != new_parent) return -EIO; - cgrp = __d_cgrp(old_dentry); - /* * This isn't a proper migration and its usefulness is very * limited. Disallow if sane_behavior. @@ -2505,186 +2221,43 @@ static int cgroup_rename(struct inode *old_dir, struct dentry *old_dentry, if (cgroup_sane_behavior(cgrp)) return -EPERM; - name = cgroup_alloc_name(new_dentry->d_name.name); + name = cgroup_alloc_name(new_name_str); if (!name) return -ENOMEM; - ret = simple_rename(old_dir, old_dentry, new_dir, new_dentry); - if (ret) { - kfree(name); - return ret; + mutex_lock(&cgroup_tree_mutex); + mutex_lock(&cgroup_mutex); + + ret = kernfs_rename(kn, new_parent, new_name_str); + if (!ret) { + old_name = rcu_dereference_protected(cgrp->name, true); + rcu_assign_pointer(cgrp->name, name); + } else { + old_name = name; } - old_name = rcu_dereference_protected(cgrp->name, true); - rcu_assign_pointer(cgrp->name, name); + mutex_unlock(&cgroup_mutex); + mutex_unlock(&cgroup_tree_mutex); kfree_rcu(old_name, rcu_head); - return 0; -} - -static struct simple_xattrs *__d_xattrs(struct dentry *dentry) -{ - if (S_ISDIR(dentry->d_inode->i_mode)) - return &__d_cgrp(dentry)->xattrs; - else - return &__d_cfe(dentry)->xattrs; -} - -static inline int xattr_enabled(struct dentry *dentry) -{ - struct cgroupfs_root *root = dentry->d_sb->s_fs_info; - return root->flags & CGRP_ROOT_XATTR; -} - -static bool is_valid_xattr(const char *name) -{ - if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) || - !strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) - return true; - return false; -} - -static int cgroup_setxattr(struct dentry *dentry, const char *name, - const void *val, size_t size, int flags) -{ - if (!xattr_enabled(dentry)) - return -EOPNOTSUPP; - if (!is_valid_xattr(name)) - return -EINVAL; - return simple_xattr_set(__d_xattrs(dentry), name, val, size, flags); -} - -static int cgroup_removexattr(struct dentry *dentry, const char *name) -{ - if (!xattr_enabled(dentry)) - return -EOPNOTSUPP; - if (!is_valid_xattr(name)) - return -EINVAL; - return simple_xattr_remove(__d_xattrs(dentry), name); -} - -static ssize_t cgroup_getxattr(struct dentry *dentry, const char *name, - void *buf, size_t size) -{ - if (!xattr_enabled(dentry)) - return -EOPNOTSUPP; - if (!is_valid_xattr(name)) - return -EINVAL; - return simple_xattr_get(__d_xattrs(dentry), name, buf, size); -} - -static ssize_t cgroup_listxattr(struct dentry *dentry, char *buf, size_t size) -{ - if (!xattr_enabled(dentry)) - return -EOPNOTSUPP; - return simple_xattr_list(__d_xattrs(dentry), buf, size); -} - -static const struct file_operations cgroup_file_operations = { - .read = seq_read, - .write = cgroup_file_write, - .llseek = generic_file_llseek, - .open = cgroup_file_open, - .release = cgroup_file_release, -}; - -static const struct inode_operations cgroup_file_inode_operations = { - .setxattr = cgroup_setxattr, - .getxattr = cgroup_getxattr, - .listxattr = cgroup_listxattr, - .removexattr = cgroup_removexattr, -}; - -static const struct inode_operations cgroup_dir_inode_operations = { - .lookup = simple_lookup, - .mkdir = cgroup_mkdir, - .rmdir = cgroup_rmdir, - .rename = cgroup_rename, - .setxattr = cgroup_setxattr, - .getxattr = cgroup_getxattr, - .listxattr = cgroup_listxattr, - .removexattr = cgroup_removexattr, -}; - -static int cgroup_create_file(struct dentry *dentry, umode_t mode, - struct super_block *sb) -{ - struct inode *inode; - - if (!dentry) - return -ENOENT; - if (dentry->d_inode) - return -EEXIST; - - inode = cgroup_new_inode(mode, sb); - if (!inode) - return -ENOMEM; - - if (S_ISDIR(mode)) { - inode->i_op = &cgroup_dir_inode_operations; - inode->i_fop = &simple_dir_operations; - - /* start off with i_nlink == 2 (for "." entry) */ - inc_nlink(inode); - inc_nlink(dentry->d_parent->d_inode); - - /* - * Control reaches here with cgroup_mutex held. - * @inode->i_mutex should nest outside cgroup_mutex but we - * want to populate it immediately without releasing - * cgroup_mutex. As @inode isn't visible to anyone else - * yet, trylock will always succeed without affecting - * lockdep checks. - */ - WARN_ON_ONCE(!mutex_trylock(&inode->i_mutex)); - } else if (S_ISREG(mode)) { - inode->i_size = 0; - inode->i_fop = &cgroup_file_operations; - inode->i_op = &cgroup_file_inode_operations; - } - d_instantiate(dentry, inode); - dget(dentry); /* Extra count - pin the dentry in core */ - return 0; + return ret; } static int cgroup_add_file(struct cgroup *cgrp, struct cftype *cft) { - struct dentry *dir = cgrp->dentry; - struct cgroup *parent = __d_cgrp(dir); - struct dentry *dentry; - struct cfent *cfe; - int error; - umode_t mode; char name[CGROUP_FILE_NAME_MAX]; + struct kernfs_node *kn; + struct lock_class_key *key = NULL; - BUG_ON(!mutex_is_locked(&dir->d_inode->i_mutex)); - - cfe = kzalloc(sizeof(*cfe), GFP_KERNEL); - if (!cfe) - return -ENOMEM; - - cgroup_file_name(cgrp, cft, name); - dentry = lookup_one_len(name, dir, strlen(name)); - if (IS_ERR(dentry)) { - error = PTR_ERR(dentry); - goto out; - } - - cfe->type = (void *)cft; - cfe->dentry = dentry; - dentry->d_fsdata = cfe; - simple_xattrs_init(&cfe->xattrs); - - mode = cgroup_file_mode(cft); - error = cgroup_create_file(dentry, mode | S_IFREG, cgrp->root->sb); - if (!error) { - list_add_tail(&cfe->node, &parent->files); - cfe = NULL; - } - dput(dentry); -out: - kfree(cfe); - return error; +#ifdef CONFIG_DEBUG_LOCK_ALLOC + key = &cft->lockdep_key; +#endif + kn = __kernfs_create_file(cgrp->kn, cgroup_file_name(cgrp, cft, name), + cgroup_file_mode(cft), 0, cft->kf_ops, cft, + NULL, false, key); + if (IS_ERR(kn)) + return PTR_ERR(kn); + return 0; } /** @@ -2704,7 +2277,6 @@ static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[], struct cftype *cft; int ret; - lockdep_assert_held(&cgrp->dentry->d_inode->i_mutex); lockdep_assert_held(&cgroup_tree_mutex); for (cft = cfts; cft->name[0] != '\0'; cft++) { @@ -2749,9 +2321,7 @@ static int cgroup_cfts_commit(struct cftype *cfts, bool is_add) LIST_HEAD(pending); struct cgroup_subsys *ss = cfts[0].ss; struct cgroup *root = &ss->root->top_cgroup; - struct super_block *sb = ss->root->sb; struct cgroup *prev = NULL; - struct inode *inode; struct cgroup_subsys_state *css; u64 update_before; int ret = 0; @@ -2759,12 +2329,13 @@ static int cgroup_cfts_commit(struct cftype *cfts, bool is_add) mutex_unlock(&cgroup_mutex); /* %NULL @cfts indicates abort and don't bother if @ss isn't attached */ - if (!cfts || ss->root == &cgroup_dummy_root || - !atomic_inc_not_zero(&sb->s_active)) { + if (!cfts || ss->root == &cgroup_dummy_root) { mutex_unlock(&cgroup_tree_mutex); return 0; } + cgroup_get_root(ss->root); + /* * All cgroups which are created after we drop cgroup_mutex will * have the updated set of files, so we only need to update the @@ -2779,18 +2350,16 @@ static int cgroup_cfts_commit(struct cftype *cfts, bool is_add) if (cgroup_is_dead(cgrp)) continue; - inode = cgrp->dentry->d_inode; cgroup_get(cgrp); if (prev) cgroup_put(prev); prev = cgrp; - mutex_unlock(&cgroup_tree_mutex); - mutex_lock(&inode->i_mutex); - mutex_lock(&cgroup_tree_mutex); - if (cgrp->serial_nr < update_before && !cgroup_is_dead(cgrp)) + if (cgrp->serial_nr < update_before && !cgroup_is_dead(cgrp)) { ret = cgroup_addrm_files(cgrp, cfts, is_add); - mutex_unlock(&inode->i_mutex); + if (is_add) + kernfs_activate(cgrp->kn); + } if (ret) break; } @@ -2804,16 +2373,45 @@ static void cgroup_exit_cftypes(struct cftype *cfts) { struct cftype *cft; - for (cft = cfts; cft->name[0] != '\0'; cft++) + for (cft = cfts; cft->name[0] != '\0'; cft++) { + /* free copy for custom atomic_write_len, see init_cftypes() */ + if (cft->max_write_len && cft->max_write_len != PAGE_SIZE) + kfree(cft->kf_ops); + cft->kf_ops = NULL; cft->ss = NULL; + } } -static void cgroup_init_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) +static int cgroup_init_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) { struct cftype *cft; - for (cft = cfts; cft->name[0] != '\0'; cft++) + for (cft = cfts; cft->name[0] != '\0'; cft++) { + struct kernfs_ops *kf_ops; + + if (cft->seq_start) + kf_ops = &cgroup_kf_ops; + else + kf_ops = &cgroup_kf_single_ops; + + /* + * Ugh... if @cft wants a custom max_write_len, we need to + * make a copy of kf_ops to set its atomic_write_len. + */ + if (cft->max_write_len && cft->max_write_len != PAGE_SIZE) { + kf_ops = kmemdup(kf_ops, sizeof(*kf_ops), GFP_KERNEL); + if (!kf_ops) { + cgroup_exit_cftypes(cfts); + return -ENOMEM; + } + kf_ops->atomic_write_len = cft->max_write_len; + } + + cft->kf_ops = kf_ops; cft->ss = ss; + } + + return 0; } /** @@ -2839,7 +2437,9 @@ int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) if (!set) return -ENOMEM; - cgroup_init_cftypes(ss, cfts); + ret = cgroup_init_cftypes(ss, cfts); + if (ret) + return ret; cgroup_cfts_prepare(); set->cfts = cfts; @@ -3706,21 +3306,27 @@ static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type, */ int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) { - int ret = -EINVAL; + struct kernfs_node *kn = kernfs_node_from_dentry(dentry); struct cgroup *cgrp; struct css_task_iter it; struct task_struct *tsk; + /* it should be kernfs_node belonging to cgroupfs and is a directory */ + if (dentry->d_sb->s_type != &cgroup_fs_type || !kn || + kernfs_type(kn) != KERNFS_DIR) + return -EINVAL; + /* - * Validate dentry by checking the superblock operations, - * and make sure it's a directory. + * We aren't being called from kernfs and there's no guarantee on + * @kn->priv's validity. For this and css_tryget_from_dir(), + * @kn->priv is RCU safe. Let's do the RCU dancing. */ - if (dentry->d_sb->s_op != &cgroup_ops || - !S_ISDIR(dentry->d_inode->i_mode)) - goto err; - - ret = 0; - cgrp = dentry->d_fsdata; + rcu_read_lock(); + cgrp = rcu_dereference(kn->priv); + if (!cgrp) { + rcu_read_unlock(); + return -ENOENT; + } css_task_iter_start(&cgrp->dummy_css, &it); while ((tsk = css_task_iter_next(&it))) { @@ -3745,8 +3351,8 @@ int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) } css_task_iter_end(&it); -err: - return ret; + rcu_read_unlock(); + return 0; } @@ -3764,7 +3370,7 @@ static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) * after a seek to the start). Use a binary-search to find the * next pid to display, if any */ - struct cgroup_open_file *of = s->private; + struct kernfs_open_file *of = s->private; struct cgroup *cgrp = seq_css(s)->cgroup; struct cgroup_pidlist *l; enum cgroup_filetype type = seq_cft(s)->private; @@ -3819,7 +3425,7 @@ static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) static void cgroup_pidlist_stop(struct seq_file *s, void *v) { - struct cgroup_open_file *of = s->private; + struct kernfs_open_file *of = s->private; struct cgroup_pidlist *l = of->priv; if (l) @@ -3830,7 +3436,7 @@ static void cgroup_pidlist_stop(struct seq_file *s, void *v) static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) { - struct cgroup_open_file *of = s->private; + struct kernfs_open_file *of = s->private; struct cgroup_pidlist *l = of->priv; pid_t *p = v; pid_t *end = l->list + l->length; @@ -3880,21 +3486,6 @@ static int cgroup_write_notify_on_release(struct cgroup_subsys_state *css, return 0; } -/* - * When dput() is called asynchronously, if umount has been done and - * then deactivate_super() in cgroup_free_fn() kills the superblock, - * there's a small window that vfs will see the root dentry with non-zero - * refcnt and trigger BUG(). - * - * That's why we hold a reference before dput() and drop it right after. - */ -static void cgroup_dput(struct cgroup *cgrp) -{ - cgroup_get_root(cgrp->root); - cgroup_put(cgrp); - cgroup_put_root(cgrp->root); -} - static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css, struct cftype *cft) { @@ -4029,7 +3620,7 @@ static void css_free_work_fn(struct work_struct *work) css_put(css->parent); css->ss->css_free(css); - cgroup_dput(cgrp); + cgroup_put(cgrp); } static void css_free_rcu_fn(struct rcu_head *rcu_head) @@ -4037,10 +3628,6 @@ static void css_free_rcu_fn(struct rcu_head *rcu_head) struct cgroup_subsys_state *css = container_of(rcu_head, struct cgroup_subsys_state, rcu_head); - /* - * css holds an extra ref to @cgrp->dentry which is put on the last - * css_put(). dput() requires process context which we don't have. - */ INIT_WORK(&css->destroy_work, css_free_work_fn); queue_work(cgroup_destroy_wq, &css->destroy_work); } @@ -4122,7 +3709,6 @@ static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss) struct cgroup_subsys_state *css; int err; - lockdep_assert_held(&cgrp->dentry->d_inode->i_mutex); lockdep_assert_held(&cgroup_mutex); css = ss->css_alloc(cgroup_css(parent, ss)); @@ -4163,30 +3749,28 @@ err_free: return err; } -/* +/** * cgroup_create - create a cgroup * @parent: cgroup that will be parent of the new cgroup - * @dentry: dentry of the new cgroup - * @mode: mode to set on new inode - * - * Must be called with the mutex on the parent inode held + * @name_str: name of the new cgroup + * @mode: mode to set on new cgroup */ -static long cgroup_create(struct cgroup *parent, struct dentry *dentry, - umode_t mode) +static long cgroup_create(struct cgroup *parent, const char *name_str, + umode_t mode) { struct cgroup *cgrp; struct cgroup_name *name; struct cgroupfs_root *root = parent->root; int ssid, err; struct cgroup_subsys *ss; - struct super_block *sb = root->sb; + struct kernfs_node *kn; /* allocate the cgroup and its ID, 0 is reserved for the root */ cgrp = kzalloc(sizeof(*cgrp), GFP_KERNEL); if (!cgrp) return -ENOMEM; - name = cgroup_alloc_name(dentry->d_name.name); + name = cgroup_alloc_name(name_str); if (!name) { err = -ENOMEM; goto err_free_cgrp; @@ -4217,18 +3801,8 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, goto err_unlock; } - /* Grab a reference on the superblock so the hierarchy doesn't - * get deleted on unmount if there are child cgroups. This - * can be done outside cgroup_mutex, since the sb can't - * disappear while someone has an open control file on the - * fs */ - cgroup_get_root(root); - init_cgroup_housekeeping(cgrp); - dentry->d_fsdata = cgrp; - cgrp->dentry = dentry; - cgrp->parent = parent; cgrp->dummy_css.parent = &parent->dummy_css; cgrp->root = parent->root; @@ -4239,15 +3813,13 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &parent->flags)) set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags); - /* - * Create directory. cgroup_create_file() returns with the new - * directory locked on success so that it can be populated without - * dropping cgroup_mutex. - */ - err = cgroup_create_file(dentry, S_IFDIR | mode, sb); - if (err < 0) + /* create the directory */ + kn = kernfs_create_dir(parent->kn, name->name, mode, cgrp); + if (IS_ERR(kn)) { + err = PTR_ERR(kn); goto err_free_id; - lockdep_assert_held(&dentry->d_inode->i_mutex); + } + cgrp->kn = kn; cgrp->serial_nr = cgroup_serial_nr_next++; @@ -4255,7 +3827,11 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, list_add_tail_rcu(&cgrp->sibling, &cgrp->parent->children); root->number_of_cgroups++; - /* hold a ref to the parent's dentry */ + /* + * Grab a reference on the root and parent so that they don't get + * deleted while there are child cgroups. + */ + cgroup_get_root(root); cgroup_get(parent); /* @@ -4277,16 +3853,15 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry, } } + kernfs_activate(kn); + mutex_unlock(&cgroup_mutex); mutex_unlock(&cgroup_tree_mutex); - mutex_unlock(&cgrp->dentry->d_inode->i_mutex); return 0; err_free_id: idr_remove(&root->cgroup_idr, cgrp->id); - /* Release the reference count that we took on the superblock */ - cgroup_put_root(root); err_unlock: mutex_unlock(&cgroup_mutex); err_unlock_tree: @@ -4300,16 +3875,15 @@ err_destroy: cgroup_destroy_locked(cgrp); mutex_unlock(&cgroup_mutex); mutex_unlock(&cgroup_tree_mutex); - mutex_unlock(&dentry->d_inode->i_mutex); return err; } -static int cgroup_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) +static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, + umode_t mode) { - struct cgroup *c_parent = dentry->d_parent->d_fsdata; + struct cgroup *parent = parent_kn->priv; - /* the vfs holds inode->i_mutex already */ - return cgroup_create(c_parent, dentry, mode | S_IFDIR); + return cgroup_create(parent, name, mode); } /* @@ -4373,6 +3947,10 @@ static void css_killed_ref_fn(struct percpu_ref *ref) */ static void kill_css(struct cgroup_subsys_state *css) { + /* + * This must happen before css is disassociated with its cgroup. + * See seq_css() for details. + */ cgroup_clear_dir(css->cgroup, 1 << css->ss->id); /* @@ -4421,13 +3999,12 @@ static void kill_css(struct cgroup_subsys_state *css) static int cgroup_destroy_locked(struct cgroup *cgrp) __releases(&cgroup_mutex) __acquires(&cgroup_mutex) { - struct dentry *d = cgrp->dentry; - struct cgroup_subsys_state *css; struct cgroup *child; + struct cgroup_subsys_state *css; + struct kernfs_node *kn; bool empty; int ssid; - lockdep_assert_held(&d->d_inode->i_mutex); lockdep_assert_held(&cgroup_tree_mutex); lockdep_assert_held(&cgroup_mutex); @@ -4492,15 +4069,24 @@ static int cgroup_destroy_locked(struct cgroup *cgrp) if (!cgrp->nr_css) cgroup_destroy_css_killed(cgrp); + /* remove @cgrp directory along with the base files */ + mutex_unlock(&cgroup_mutex); + /* - * Clear the base files and remove @cgrp directory. The removal - * puts the base ref but we aren't quite done with @cgrp yet, so - * hold onto it. + * There are two control paths which try to determine cgroup from + * dentry without going through kernfs - cgroupstats_build() and + * css_tryget_from_dir(). Those are supported by RCU protecting + * clearing of cgrp->kn->priv backpointer, which should happen + * after all files under it have been removed. */ - mutex_unlock(&cgroup_mutex); - cgroup_addrm_files(cgrp, cgroup_base_files, false); - dget(d); - cgroup_d_remove_dir(d); + kn = cgrp->kn; + kernfs_get(kn); + + kernfs_remove(cgrp->kn); + + RCU_INIT_POINTER(*(void __rcu __force **)&cgrp->kn->priv, NULL); + kernfs_put(kn); + mutex_lock(&cgroup_mutex); return 0; @@ -4531,19 +4117,46 @@ static void cgroup_destroy_css_killed(struct cgroup *cgrp) check_for_release(parent); } -static int cgroup_rmdir(struct inode *unused_dir, struct dentry *dentry) +static int cgroup_rmdir(struct kernfs_node *kn) { - int ret; + struct cgroup *cgrp = kn->priv; + int ret = 0; + + /* + * This is self-destruction but @kn can't be removed while this + * callback is in progress. Let's break active protection. Once + * the protection is broken, @cgrp can be destroyed at any point. + * Pin it so that it stays accessible. + */ + cgroup_get(cgrp); + kernfs_break_active_protection(kn); mutex_lock(&cgroup_tree_mutex); mutex_lock(&cgroup_mutex); - ret = cgroup_destroy_locked(dentry->d_fsdata); + + /* + * @cgrp might already have been destroyed while we're trying to + * grab the mutexes. + */ + if (!cgroup_is_dead(cgrp)) + ret = cgroup_destroy_locked(cgrp); + mutex_unlock(&cgroup_mutex); mutex_unlock(&cgroup_tree_mutex); + kernfs_unbreak_active_protection(kn); + cgroup_put(cgrp); return ret; } +static struct kernfs_syscall_ops cgroup_kf_syscall_ops = { + .remount_fs = cgroup_remount, + .show_options = cgroup_show_options, + .mkdir = cgroup_mkdir, + .rmdir = cgroup_rmdir, + .rename = cgroup_rename, +}; + static void __init cgroup_init_subsys(struct cgroup_subsys *ss) { struct cgroup_subsys_state *css; @@ -4635,11 +4248,7 @@ int __init cgroup_init(void) unsigned long key; int i, err; - err = bdi_init(&cgroup_backing_dev_info); - if (err) - return err; - - cgroup_init_cftypes(NULL, cgroup_base_files); + BUG_ON(cgroup_init_cftypes(NULL, cgroup_base_files)); for_each_subsys(ss, i) { if (!ss->early_init) @@ -4669,24 +4278,17 @@ int __init cgroup_init(void) mutex_unlock(&cgroup_mutex); cgroup_kobj = kobject_create_and_add("cgroup", fs_kobj); - if (!cgroup_kobj) { - err = -ENOMEM; - goto out; - } + if (!cgroup_kobj) + return -ENOMEM; err = register_filesystem(&cgroup_fs_type); if (err < 0) { kobject_put(cgroup_kobj); - goto out; + return err; } proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations); - -out: - if (err) - bdi_destroy(&cgroup_backing_dev_info); - - return err; + return 0; } static int __init cgroup_wq_init(void) @@ -5095,18 +4697,25 @@ __setup("cgroup_disable=", cgroup_disable); struct cgroup_subsys_state *css_tryget_from_dir(struct dentry *dentry, struct cgroup_subsys *ss) { + struct kernfs_node *kn = kernfs_node_from_dentry(dentry); + struct cgroup_subsys_state *css = NULL; struct cgroup *cgrp; - struct cgroup_subsys_state *css; /* is @dentry a cgroup dir? */ - if (!dentry->d_inode || - dentry->d_inode->i_op != &cgroup_dir_inode_operations) + if (dentry->d_sb->s_type != &cgroup_fs_type || !kn || + kernfs_type(kn) != KERNFS_DIR) return ERR_PTR(-EBADF); rcu_read_lock(); - cgrp = __d_cgrp(dentry); - css = cgroup_css(cgrp, ss); + /* + * This path doesn't originate from kernfs and @kn could already + * have been or be removed at any point. @kn->priv is RCU + * protected for this access. See destroy_locked() for details. + */ + cgrp = rcu_dereference(kn->priv); + if (cgrp) + css = cgroup_css(cgrp, ss); if (!css || !css_tryget(css)) css = ERR_PTR(-ENOENT); |
