diff options
| -rw-r--r-- | fs/kernfs/dir.c | 66 | ||||
| -rw-r--r-- | fs/kernfs/kernfs-internal.h | 3 | ||||
| -rw-r--r-- | include/linux/kernfs.h | 1 |
3 files changed, 37 insertions, 33 deletions
diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index 5cf137b..d0fd739 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -22,6 +22,12 @@ DEFINE_MUTEX(kernfs_mutex); #define rb_to_kn(X) rb_entry((X), struct kernfs_node, rb) +static bool kernfs_active(struct kernfs_node *kn) +{ + lockdep_assert_held(&kernfs_mutex); + return atomic_read(&kn->active) >= 0; +} + static bool kernfs_lockdep(struct kernfs_node *kn) { #ifdef CONFIG_DEBUG_LOCK_ALLOC @@ -183,25 +189,20 @@ void kernfs_put_active(struct kernfs_node *kn) } /** - * kernfs_deactivate - deactivate kernfs_node - * @kn: kernfs_node to deactivate + * kernfs_drain - drain kernfs_node + * @kn: kernfs_node to drain * - * Deny new active references, drain existing ones and nuke all - * existing mmaps. Mutiple removers may invoke this function - * concurrently on @kn and all will return after deactivation and - * draining are complete. + * Drain existing usages and nuke all existing mmaps of @kn. Mutiple + * removers may invoke this function concurrently on @kn and all will + * return after draining is complete. */ -static void kernfs_deactivate(struct kernfs_node *kn) +static void kernfs_drain(struct kernfs_node *kn) __releases(&kernfs_mutex) __acquires(&kernfs_mutex) { struct kernfs_root *root = kernfs_root(kn); lockdep_assert_held(&kernfs_mutex); - BUG_ON(!(kn->flags & KERNFS_REMOVED)); - - /* only the first invocation on @kn should deactivate it */ - if (atomic_read(&kn->active) >= 0) - atomic_add(KN_DEACTIVATED_BIAS, &kn->active); + WARN_ON_ONCE(kernfs_active(kn)); mutex_unlock(&kernfs_mutex); @@ -253,13 +254,15 @@ void kernfs_put(struct kernfs_node *kn) return; root = kernfs_root(kn); repeat: - /* Moving/renaming is always done while holding reference. + /* + * Moving/renaming is always done while holding reference. * kn->parent won't change beneath us. */ parent = kn->parent; - WARN(!(kn->flags & KERNFS_REMOVED), "kernfs: free using entry: %s/%s\n", - parent ? parent->name : "", kn->name); + 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)); if (kernfs_type(kn) == KERNFS_LINK) kernfs_put(kn->symlink.target_kn); @@ -301,8 +304,8 @@ static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags) kn = dentry->d_fsdata; mutex_lock(&kernfs_mutex); - /* The kernfs node has been deleted */ - if (kn->flags & KERNFS_REMOVED) + /* The kernfs node has been deactivated */ + if (!kernfs_active(kn)) goto out_bad; /* The kernfs node has been moved? */ @@ -371,12 +374,12 @@ static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root, kn->ino = ret; atomic_set(&kn->count, 1); - atomic_set(&kn->active, 0); + atomic_set(&kn->active, KN_DEACTIVATED_BIAS); RB_CLEAR_NODE(&kn->rb); kn->name = name; kn->mode = mode; - kn->flags = flags | KERNFS_REMOVED; + kn->flags = flags; return kn; @@ -432,7 +435,7 @@ int kernfs_add_one(struct kernfs_node *kn) goto out_unlock; ret = -ENOENT; - if (parent->flags & KERNFS_REMOVED) + if (!kernfs_active(parent)) goto out_unlock; kn->hash = kernfs_name_hash(kn->name, kn->ns); @@ -449,7 +452,7 @@ int kernfs_add_one(struct kernfs_node *kn) } /* Mark the entry added into directory tree */ - kn->flags &= ~KERNFS_REMOVED; + atomic_sub(KN_DEACTIVATED_BIAS, &kn->active); ret = 0; out_unlock: mutex_unlock(&kernfs_mutex); @@ -549,7 +552,7 @@ struct kernfs_root *kernfs_create_root(struct kernfs_dir_ops *kdops, void *priv) return ERR_PTR(-ENOMEM); } - kn->flags &= ~KERNFS_REMOVED; + atomic_sub(KN_DEACTIVATED_BIAS, &kn->active); kn->priv = priv; kn->dir.root = root; @@ -763,24 +766,25 @@ static void __kernfs_remove(struct kernfs_node *kn) pr_debug("kernfs %s: removing\n", kn->name); - /* disable lookup and node creation under @kn */ + /* prevent any new usage under @kn by deactivating all nodes */ pos = NULL; while ((pos = kernfs_next_descendant_post(pos, kn))) - pos->flags |= KERNFS_REMOVED; + if (kernfs_active(pos)) + atomic_add(KN_DEACTIVATED_BIAS, &pos->active); /* deactivate and unlink the subtree node-by-node */ do { pos = kernfs_leftmost_descendant(kn); /* - * kernfs_deactivate() drops kernfs_mutex temporarily and - * @pos's base ref could have been put by someone else by - * the time the function returns. Make sure it doesn't go - * away underneath us. + * kernfs_drain() drops kernfs_mutex temporarily and @pos's + * base ref could have been put by someone else by the time + * the function returns. Make sure it doesn't go away + * underneath us. */ kernfs_get(pos); - kernfs_deactivate(pos); + kernfs_drain(pos); /* * kernfs_unlink_sibling() succeeds once per node. Use it @@ -865,7 +869,7 @@ int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent, mutex_lock(&kernfs_mutex); error = -ENOENT; - if ((kn->flags | new_parent->flags) & KERNFS_REMOVED) + if (!kernfs_active(kn) || !kernfs_active(new_parent)) goto out; error = 0; @@ -925,7 +929,7 @@ static struct kernfs_node *kernfs_dir_pos(const void *ns, struct kernfs_node *parent, loff_t hash, struct kernfs_node *pos) { if (pos) { - int valid = !(pos->flags & KERNFS_REMOVED) && + int valid = kernfs_active(pos) && pos->parent == parent && hash == pos->hash; kernfs_put(pos); if (!valid) diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h index 46b58de..a91d7a1 100644 --- a/fs/kernfs/kernfs-internal.h +++ b/fs/kernfs/kernfs-internal.h @@ -26,7 +26,8 @@ struct kernfs_iattrs { struct simple_xattrs xattrs; }; -#define KN_DEACTIVATED_BIAS INT_MIN +/* +1 to avoid triggering overflow warning when negating it */ +#define KN_DEACTIVATED_BIAS (INT_MIN + 1) /* KERNFS_TYPE_MASK and types are defined in include/linux/kernfs.h */ diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h index dc4cd6c..917bc6c 100644 --- a/include/linux/kernfs.h +++ b/include/linux/kernfs.h @@ -38,7 +38,6 @@ enum kernfs_node_type { #define KERNFS_FLAG_MASK ~KERNFS_TYPE_MASK enum kernfs_node_flag { - KERNFS_REMOVED = 0x0010, KERNFS_NS = 0x0020, KERNFS_HAS_SEQ_SHOW = 0x0040, KERNFS_HAS_MMAP = 0x0080, |
