diff options
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/kernfs/dir.c | 113 | ||||
| -rw-r--r-- | fs/kernfs/file.c | 4 | ||||
| -rw-r--r-- | fs/kernfs/kernfs-internal.h | 5 | ||||
| -rw-r--r-- | fs/kernfs/mount.c | 5 | ||||
| -rw-r--r-- | fs/kernfs/symlink.c | 7 | ||||
| -rw-r--r-- | fs/sysfs/dir.c | 2 |
6 files changed, 78 insertions, 58 deletions
diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index 1d370c497e8a..c5a578c46759 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -51,14 +51,6 @@ static bool kernfs_lockdep(struct kernfs_node *kn) #endif } -static int kernfs_name_locked(struct kernfs_node *kn, char *buf, size_t buflen) -{ - if (!kn) - return strscpy(buf, "(null)", buflen); - - return strscpy(buf, rcu_access_pointer(kn->__parent) ? kn->name : "/", buflen); -} - /* kernfs_node_depth - compute depth from @from to @to */ static size_t kernfs_depth(struct kernfs_node *from, struct kernfs_node *to) { @@ -168,11 +160,13 @@ static int kernfs_path_from_node_locked(struct kernfs_node *kn_to, /* Calculate how many bytes we need for the rest */ for (i = depth_to - 1; i >= 0; i--) { + const char *name; for (kn = kn_to, j = 0; j < i; j++) kn = rcu_dereference(kn->__parent); - len += scnprintf(buf + len, buflen - len, "/%s", kn->name); + name = rcu_dereference(kn->name); + len += scnprintf(buf + len, buflen - len, "/%s", name); } return len; @@ -196,13 +190,18 @@ static int kernfs_path_from_node_locked(struct kernfs_node *kn_to, */ int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen) { - unsigned long flags; - int ret; + struct kernfs_node *kn_parent; - read_lock_irqsave(&kernfs_rename_lock, flags); - ret = kernfs_name_locked(kn, buf, buflen); - read_unlock_irqrestore(&kernfs_rename_lock, flags); - return ret; + if (!kn) + return strscpy(buf, "(null)", buflen); + + guard(rcu)(); + /* + * KERNFS_ROOT_INVARIANT_PARENT is ignored here. The name is RCU freed and + * the parent is either existing or not. + */ + kn_parent = rcu_dereference(kn->__parent); + return strscpy(buf, kn_parent ? rcu_dereference(kn->name) : "/", buflen); } /** @@ -224,14 +223,17 @@ int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen) int kernfs_path_from_node(struct kernfs_node *to, struct kernfs_node *from, char *buf, size_t buflen) { - unsigned long flags; - int ret; + struct kernfs_root *root; guard(rcu)(); - read_lock_irqsave(&kernfs_rename_lock, flags); - ret = kernfs_path_from_node_locked(to, from, buf, buflen); - read_unlock_irqrestore(&kernfs_rename_lock, flags); - return ret; + if (to) { + root = kernfs_root(to); + if (!(root->flags & KERNFS_ROOT_INVARIANT_PARENT)) { + guard(read_lock_irqsave)(&kernfs_rename_lock); + return kernfs_path_from_node_locked(to, from, buf, buflen); + } + } + return kernfs_path_from_node_locked(to, from, buf, buflen); } EXPORT_SYMBOL_GPL(kernfs_path_from_node); @@ -338,13 +340,13 @@ static int kernfs_name_compare(unsigned int hash, const char *name, return -1; if (ns > kn->ns) return 1; - return strcmp(name, kn->name); + return strcmp(name, kernfs_rcu_name(kn)); } static int kernfs_sd_compare(const struct kernfs_node *left, const struct kernfs_node *right) { - return kernfs_name_compare(left->hash, left->name, left->ns, right); + return kernfs_name_compare(left->hash, kernfs_rcu_name(left), left->ns, right); } /** @@ -542,7 +544,8 @@ static void kernfs_free_rcu(struct rcu_head *rcu) { struct kernfs_node *kn = container_of(rcu, struct kernfs_node, rcu); - kfree_const(kn->name); + /* If the whole node goes away, then name can't be used outside */ + kfree_const(rcu_access_pointer(kn->name)); if (kn->iattr) { simple_xattrs_free(&kn->iattr->xattrs, NULL); @@ -575,7 +578,8 @@ void kernfs_put(struct kernfs_node *kn) WARN_ONCE(atomic_read(&kn->active) != KN_DEACTIVATED_BIAS, "kernfs_put: %s/%s: released with incorrect active_ref %d\n", - parent ? parent->name : "", kn->name, atomic_read(&kn->active)); + parent ? rcu_dereference(parent->name) : "", + rcu_dereference(kn->name), atomic_read(&kn->active)); if (kernfs_type(kn) == KERNFS_LINK) kernfs_put(kn->symlink.target_kn); @@ -652,7 +656,7 @@ static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root, atomic_set(&kn->active, KN_DEACTIVATED_BIAS); RB_CLEAR_NODE(&kn->rb); - kn->name = name; + rcu_assign_pointer(kn->name, name); kn->mode = mode; kn->flags = flags; @@ -790,7 +794,8 @@ int kernfs_add_one(struct kernfs_node *kn) ret = -EINVAL; has_ns = kernfs_ns_enabled(parent); if (WARN(has_ns != (bool)kn->ns, KERN_WARNING "kernfs: ns %s in '%s' for '%s'\n", - has_ns ? "required" : "invalid", parent->name, kn->name)) + has_ns ? "required" : "invalid", + kernfs_rcu_name(parent), kernfs_rcu_name(kn))) goto out_unlock; if (kernfs_type(parent) != KERNFS_DIR) @@ -800,7 +805,7 @@ int kernfs_add_one(struct kernfs_node *kn) if (parent->flags & (KERNFS_REMOVING | KERNFS_EMPTY_DIR)) goto out_unlock; - kn->hash = kernfs_name_hash(kn->name, kn->ns); + kn->hash = kernfs_name_hash(kernfs_rcu_name(kn), kn->ns); ret = kernfs_link_sibling(kn); if (ret) @@ -856,7 +861,7 @@ static struct kernfs_node *kernfs_find_ns(struct kernfs_node *parent, if (has_ns != (bool)ns) { WARN(1, KERN_WARNING "kernfs: ns %s in '%s' for '%s'\n", - has_ns ? "required" : "invalid", parent->name, name); + has_ns ? "required" : "invalid", kernfs_rcu_name(parent), name); return NULL; } @@ -1135,8 +1140,6 @@ static int kernfs_dop_revalidate(struct inode *dir, const struct qstr *name, /* Negative hashed dentry? */ if (d_really_is_negative(dentry)) { - struct kernfs_node *parent; - /* If the kernfs parent node has changed discard and * proceed to ->lookup. * @@ -1184,7 +1187,7 @@ static int kernfs_dop_revalidate(struct inode *dir, const struct qstr *name, goto out_bad; /* The kernfs node has been renamed */ - if (strcmp(dentry->d_name.name, kn->name) != 0) + if (strcmp(dentry->d_name.name, kernfs_rcu_name(kn)) != 0) goto out_bad; /* The kernfs node has been moved to a different namespace */ @@ -1478,7 +1481,7 @@ static void __kernfs_remove(struct kernfs_node *kn) if (kernfs_parent(kn) && RB_EMPTY_NODE(&kn->rb)) return; - pr_debug("kernfs %s: removing\n", kn->name); + pr_debug("kernfs %s: removing\n", kernfs_rcu_name(kn)); /* prevent new usage by marking all nodes removing and deactivating */ pos = NULL; @@ -1734,7 +1737,7 @@ int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent, { struct kernfs_node *old_parent; struct kernfs_root *root; - const char *old_name = NULL; + const char *old_name; int error; /* can't move or rename root */ @@ -1757,8 +1760,11 @@ int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent, } error = 0; + old_name = kernfs_rcu_name(kn); + if (!new_name) + new_name = old_name; if ((old_parent == new_parent) && (kn->ns == new_ns) && - (strcmp(kn->name, new_name) == 0)) + (strcmp(old_name, new_name) == 0)) goto out; /* nothing to rename */ error = -EEXIST; @@ -1766,7 +1772,7 @@ int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent, goto out; /* rename kernfs_node */ - if (strcmp(kn->name, new_name) != 0) { + if (strcmp(old_name, new_name) != 0) { error = -ENOMEM; new_name = kstrdup_const(new_name, GFP_KERNEL); if (!new_name) @@ -1779,27 +1785,32 @@ int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent, * Move to the appropriate place in the appropriate directories rbtree. */ kernfs_unlink_sibling(kn); - kernfs_get(new_parent); - /* rename_lock protects ->parent and ->name accessors */ - write_lock_irq(&kernfs_rename_lock); + /* rename_lock protects ->parent accessors */ + if (old_parent != new_parent) { + kernfs_get(new_parent); + write_lock_irq(&kernfs_rename_lock); - old_parent = kernfs_parent(kn); - rcu_assign_pointer(kn->__parent, new_parent); + rcu_assign_pointer(kn->__parent, new_parent); - kn->ns = new_ns; - if (new_name) { - old_name = kn->name; - kn->name = new_name; - } + kn->ns = new_ns; + if (new_name) + rcu_assign_pointer(kn->name, new_name); - write_unlock_irq(&kernfs_rename_lock); + write_unlock_irq(&kernfs_rename_lock); + kernfs_put(old_parent); + } else { + /* name assignment is RCU protected, parent is the same */ + kn->ns = new_ns; + if (new_name) + rcu_assign_pointer(kn->name, new_name); + } - kn->hash = kernfs_name_hash(kn->name, kn->ns); + kn->hash = kernfs_name_hash(new_name ?: old_name, kn->ns); kernfs_link_sibling(kn); - kernfs_put(old_parent); - kfree_const(old_name); + if (new_name && !is_kernel_rodata((unsigned long)old_name)) + kfree_rcu_mightsleep(old_name); error = 0; out: @@ -1884,7 +1895,7 @@ static int kernfs_fop_readdir(struct file *file, struct dir_context *ctx) for (pos = kernfs_dir_pos(ns, parent, ctx->pos, pos); pos; pos = kernfs_dir_next_pos(ns, parent, ctx->pos, pos)) { - const char *name = pos->name; + const char *name = kernfs_rcu_name(pos); unsigned int type = fs_umode_to_dtype(pos->mode); int len = strlen(name); ino_t ino = kernfs_ino(pos); diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c index c4ffa8dc89eb..66fe8fe41f06 100644 --- a/fs/kernfs/file.c +++ b/fs/kernfs/file.c @@ -915,6 +915,7 @@ repeat: list_for_each_entry(info, &kernfs_root(kn)->supers, node) { struct kernfs_node *parent; struct inode *p_inode = NULL; + const char *kn_name; struct inode *inode; struct qstr name; @@ -928,7 +929,8 @@ repeat: if (!inode) continue; - name = QSTR(kn->name); + kn_name = kernfs_rcu_name(kn); + name = QSTR(kn_name); parent = kernfs_get_parent(kn); if (parent) { p_inode = ilookup(info->sb, kernfs_ino(parent)); diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h index c43bee18b79f..40a2a9cd819d 100644 --- a/fs/kernfs/kernfs-internal.h +++ b/fs/kernfs/kernfs-internal.h @@ -107,6 +107,11 @@ static inline bool kernfs_root_is_locked(const struct kernfs_node *kn) return lockdep_is_held(&kernfs_root(kn)->kernfs_rwsem); } +static inline const char *kernfs_rcu_name(const struct kernfs_node *kn) +{ + return rcu_dereference_check(kn->name, kernfs_root_is_locked(kn)); +} + static inline struct kernfs_node *kernfs_parent(const struct kernfs_node *kn) { /* diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c index 2252b16e6ef0..d1f512b7bf86 100644 --- a/fs/kernfs/mount.c +++ b/fs/kernfs/mount.c @@ -231,6 +231,7 @@ struct dentry *kernfs_node_dentry(struct kernfs_node *kn, do { struct dentry *dtmp; struct kernfs_node *kntmp; + const char *name; if (kn == knparent) return dentry; @@ -239,8 +240,8 @@ struct dentry *kernfs_node_dentry(struct kernfs_node *kn, dput(dentry); return ERR_PTR(-EINVAL); } - dtmp = lookup_positive_unlocked(kntmp->name, dentry, - strlen(kntmp->name)); + name = rcu_dereference(kntmp->name); + dtmp = lookup_positive_unlocked(name, dentry, strlen(name)); dput(dentry); if (IS_ERR(dtmp)) return dtmp; diff --git a/fs/kernfs/symlink.c b/fs/kernfs/symlink.c index 05c62ca93c53..0bd8a2143723 100644 --- a/fs/kernfs/symlink.c +++ b/fs/kernfs/symlink.c @@ -81,7 +81,7 @@ static int kernfs_get_target_path(struct kernfs_node *parent, /* determine end of target string for reverse fillup */ kn = target; while (kernfs_parent(kn) && kn != base) { - len += strlen(kn->name) + 1; + len += strlen(kernfs_rcu_name(kn)) + 1; kn = kernfs_parent(kn); } @@ -95,10 +95,11 @@ static int kernfs_get_target_path(struct kernfs_node *parent, /* reverse fillup of target string from target to base */ kn = target; while (kernfs_parent(kn) && kn != base) { - int slen = strlen(kn->name); + const char *name = kernfs_rcu_name(kn); + int slen = strlen(name); len -= slen; - memcpy(s + len, kn->name, slen); + memcpy(s + len, name, slen); if (len) s[--len] = '/'; diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c index 4df2afa551dc..94e12efd92f2 100644 --- a/fs/sysfs/dir.c +++ b/fs/sysfs/dir.c @@ -123,7 +123,7 @@ int sysfs_move_dir_ns(struct kobject *kobj, struct kobject *new_parent_kobj, new_parent = new_parent_kobj && new_parent_kobj->sd ? new_parent_kobj->sd : sysfs_root_kn; - return kernfs_rename_ns(kn, new_parent, kn->name, new_ns); + return kernfs_rename_ns(kn, new_parent, NULL, new_ns); } /** |