kernfs: remove kernfs_addrm_cxt

kernfs_addrm_cxt and the accompanying kernfs_addrm_start/finish() were
added because there were operations which should be performed outside
kernfs_mutex after adding and removing kernfs_nodes.  The necessary
operations were recorded in kernfs_addrm_cxt and performed by
kernfs_addrm_finish(); however, after the recent changes which
relocated deactivation and unmapping so that they're performed
directly during removal, the only operation kernfs_addrm_finish()
performs is kernfs_put(), which can be moved inside the removal path
too.

This patch moves the kernfs_put() of the base ref to __kernfs_remove()
and remove kernfs_addrm_cxt and kernfs_addrm_start/finish().

* kernfs_add_one() is updated to grab and release the parent's active
  ref and kernfs_mutex itself.  kernfs_get/put_active() and
  kernfs_addrm_start/finish() invocations around it are removed from
  all users.

* __kernfs_remove() puts an unlinked node directly instead of chaining
  it to kernfs_addrm_cxt.  Its callers are updated to grab and release
  kernfs_mutex instead of calling kernfs_addrm_start/finish() around
  it.

v2: Updated to fit the v2 restructuring of removal path.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index f878e4f2efe7681ad35de92a74c1a1a60c894cac..770d687ee9f3c42e3ee651817ef424bf62132bbd 100644 (file)
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -398,29 +398,8 @@ struct kernfs_node *kernfs_new_node(struct kernfs_root *root, const char *name,
        return NULL;
 }
 
-/**
- *     kernfs_addrm_start - prepare for kernfs_node add/remove
- *     @acxt: pointer to kernfs_addrm_cxt to be used
- *
- *     This function is called when the caller is about to add or remove
- *     kernfs_node.  This function acquires kernfs_mutex.  @acxt is used
- *     to keep and pass context to other addrm functions.
- *
- *     LOCKING:
- *     Kernel thread context (may sleep).  kernfs_mutex is locked on
- *     return.
- */
-void kernfs_addrm_start(struct kernfs_addrm_cxt *acxt)
-       __acquires(kernfs_mutex)
-{
-       memset(acxt, 0, sizeof(*acxt));
-
-       mutex_lock(&kernfs_mutex);
-}
-
 /**
  *     kernfs_add_one - add kernfs_node to parent without warning
- *     @acxt: addrm context to use
  *     @kn: kernfs_node to be added
  *     @parent: the parent kernfs_node to add @kn to
  *
@@ -428,34 +407,29 @@ void kernfs_addrm_start(struct kernfs_addrm_cxt *acxt)
  *     parent inode if @kn is a directory and link into the children list
  *     of the parent.
  *
- *     This function should be called between calls to
- *     kernfs_addrm_start() and kernfs_addrm_finish() and should be passed
- *     the same @acxt as passed to kernfs_addrm_start().
- *
- *     LOCKING:
- *     Determined by kernfs_addrm_start().
- *
  *     RETURNS:
  *     0 on success, -EEXIST if entry with the given name already
  *     exists.
  */
-int kernfs_add_one(struct kernfs_addrm_cxt *acxt, struct kernfs_node *kn,
-                 struct kernfs_node *parent)
+int kernfs_add_one(struct kernfs_node *kn, struct kernfs_node *parent)
 {
-       bool has_ns = kernfs_ns_enabled(parent);
        struct kernfs_iattrs *ps_iattr;
+       bool has_ns;
        int ret;
 
-       WARN_ON_ONCE(atomic_read(&parent->active) < 0);
+       if (!kernfs_get_active(parent))
+               return -ENOENT;
 
-       if (has_ns != (bool)kn->ns) {
-               WARN(1, KERN_WARNING "kernfs: ns %s in '%s' for '%s'\n",
-                    has_ns ? "required" : "invalid", parent->name, kn->name);
-               return -EINVAL;
-       }
+       mutex_lock(&kernfs_mutex);
+
+       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))
+               goto out_unlock;
 
        if (kernfs_type(parent) != KERNFS_DIR)
-               return -EINVAL;
+               goto out_unlock;
 
        kn->hash = kernfs_name_hash(kn->name, kn->ns);
        kn->parent = parent;
@@ -463,7 +437,7 @@ int kernfs_add_one(struct kernfs_addrm_cxt *acxt, struct kernfs_node *kn,
 
        ret = kernfs_link_sibling(kn);
        if (ret)
-               return ret;
+               goto out_unlock;
 
        /* Update timestamps on the parent */
        ps_iattr = parent->iattr;
@@ -474,34 +448,11 @@ int kernfs_add_one(struct kernfs_addrm_cxt *acxt, struct kernfs_node *kn,
 
        /* Mark the entry added into directory tree */
        atomic_sub(KN_DEACTIVATED_BIAS, &kn->active);
-       return 0;
-}
-
-/**
- *     kernfs_addrm_finish - finish up kernfs_node add/remove
- *     @acxt: addrm context to finish up
- *
- *     Finish up kernfs_node add/remove.  Resources acquired by
- *     kernfs_addrm_start() are released and removed kernfs_nodes are
- *     cleaned up.
- *
- *     LOCKING:
- *     kernfs_mutex is released.
- */
-void kernfs_addrm_finish(struct kernfs_addrm_cxt *acxt)
-       __releases(kernfs_mutex)
-{
-       /* release resources acquired by kernfs_addrm_start() */
+       ret = 0;
+out_unlock:
        mutex_unlock(&kernfs_mutex);
-
-       /* kill removed kernfs_nodes */
-       while (acxt->removed) {
-               struct kernfs_node *kn = acxt->removed;
-
-               acxt->removed = kn->u.removed_list;
-
-               kernfs_put(kn);
-       }
+       kernfs_put_active(parent);
+       return ret;
 }
 
 /**
@@ -633,7 +584,6 @@ struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent,
                                         const char *name, umode_t mode,
                                         void *priv, const void *ns)
 {
-       struct kernfs_addrm_cxt acxt;
        struct kernfs_node *kn;
        int rc;
 
@@ -648,14 +598,7 @@ struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent,
        kn->priv = priv;
 
        /* link in */
-       rc = -ENOENT;
-       if (kernfs_get_active(parent)) {
-               kernfs_addrm_start(&acxt);
-               rc = kernfs_add_one(&acxt, kn, parent);
-               kernfs_addrm_finish(&acxt);
-               kernfs_put_active(parent);
-       }
-
+       rc = kernfs_add_one(kn, parent);
        if (!rc)
                return kn;
 
@@ -841,8 +784,7 @@ static void __kernfs_deactivate(struct kernfs_node *kn)
        }
 }
 
-static void __kernfs_remove(struct kernfs_addrm_cxt *acxt,
-                           struct kernfs_node *kn)
+static void __kernfs_remove(struct kernfs_node *kn)
 {
        struct kernfs_node *pos;
 
@@ -890,8 +832,7 @@ static void __kernfs_remove(struct kernfs_addrm_cxt *acxt,
                                ps_iattr->ia_iattr.ia_mtime = CURRENT_TIME;
                        }
 
-                       pos->u.removed_list = acxt->removed;
-                       acxt->removed = pos;
+                       kernfs_put(pos);
                }
 
                kernfs_put(pos);
@@ -906,11 +847,9 @@ static void __kernfs_remove(struct kernfs_addrm_cxt *acxt,
  */
 void kernfs_remove(struct kernfs_node *kn)
 {
-       struct kernfs_addrm_cxt acxt;
-
-       kernfs_addrm_start(&acxt);
-       __kernfs_remove(&acxt, kn);
-       kernfs_addrm_finish(&acxt);
+       mutex_lock(&kernfs_mutex);
+       __kernfs_remove(kn);
+       mutex_unlock(&kernfs_mutex);
 }
 
 /**
@@ -925,7 +864,6 @@ void kernfs_remove(struct kernfs_node *kn)
 int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name,
                             const void *ns)
 {
-       struct kernfs_addrm_cxt acxt;
        struct kernfs_node *kn;
 
        if (!parent) {
@@ -934,13 +872,13 @@ int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name,
                return -ENOENT;
        }
 
-       kernfs_addrm_start(&acxt);
+       mutex_lock(&kernfs_mutex);
 
        kn = kernfs_find_ns(parent, name, ns);
        if (kn)
-               __kernfs_remove(&acxt, kn);
+               __kernfs_remove(kn);
 
-       kernfs_addrm_finish(&acxt);
+       mutex_unlock(&kernfs_mutex);
 
        if (kn)
                return 0;

diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
index 404ffd2f27bc0bbbcfa7e45f7d812c7fe99495e9..ffe1bebf91970e4d48180571898f815d8b7f80c2 100644 (file)
--- a/fs/kernfs/file.c
+++ b/fs/kernfs/file.c
@@ -817,7 +817,6 @@ struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent,
                                         bool name_is_static,
                                         struct lock_class_key *key)
 {
-       struct kernfs_addrm_cxt acxt;
        struct kernfs_node *kn;
        unsigned flags;
        int rc;
@@ -853,14 +852,7 @@ struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent,
        if (ops->mmap)
                kn->flags |= KERNFS_HAS_MMAP;
 
-       rc = -ENOENT;
-       if (kernfs_get_active(parent)) {
-               kernfs_addrm_start(&acxt);
-               rc = kernfs_add_one(&acxt, kn, parent);
-               kernfs_addrm_finish(&acxt);
-               kernfs_put_active(parent);
-       }
-
+       rc = kernfs_add_one(kn, parent);
        if (rc) {
                kernfs_put(kn);
                return ERR_PTR(rc);

diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index e9ec38c86074fb79dfe4552e8a17680400ed1f4a..4bc57848076cdaddc13baa77d922fbb0cc104cf3 100644 (file)
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -45,13 +45,6 @@ static inline struct kernfs_root *kernfs_root(struct kernfs_node *kn)
        return kn->dir.root;
 }
 
-/*
- * Context structure to be used while adding/removing nodes.
- */
-struct kernfs_addrm_cxt {
-       struct kernfs_node      *removed;
-};
-
 /*
  * mount.c
  */
@@ -101,10 +94,7 @@ extern const struct inode_operations kernfs_dir_iops;
 
 struct kernfs_node *kernfs_get_active(struct kernfs_node *kn);
 void kernfs_put_active(struct kernfs_node *kn);
-void kernfs_addrm_start(struct kernfs_addrm_cxt *acxt);
-int kernfs_add_one(struct kernfs_addrm_cxt *acxt, struct kernfs_node *kn,
-                  struct kernfs_node *parent);
-void kernfs_addrm_finish(struct kernfs_addrm_cxt *acxt);
+int kernfs_add_one(struct kernfs_node *kn, struct kernfs_node *parent);
 struct kernfs_node *kernfs_new_node(struct kernfs_root *root, const char *name,
                                    umode_t mode, unsigned flags);
 

diff --git a/fs/kernfs/symlink.c b/fs/kernfs/symlink.c
index b2c106ca343435a508038659ce7a3aac09ddc1b8..3a939c263ede810e3857369841dd7f145d2fb947 100644 (file)
--- a/fs/kernfs/symlink.c
+++ b/fs/kernfs/symlink.c
@@ -27,7 +27,6 @@ struct kernfs_node *kernfs_create_link(struct kernfs_node *parent,
                                       struct kernfs_node *target)
 {
        struct kernfs_node *kn;
-       struct kernfs_addrm_cxt acxt;
        int error;
 
        kn = kernfs_new_node(kernfs_root(parent), name, S_IFLNK|S_IRWXUGO,
@@ -40,14 +39,7 @@ struct kernfs_node *kernfs_create_link(struct kernfs_node *parent,
        kn->symlink.target_kn = target;
        kernfs_get(target);     /* ref owned by symlink */
 
-       error = -ENOENT;
-       if (kernfs_get_active(parent)) {
-               kernfs_addrm_start(&acxt);
-               error = kernfs_add_one(&acxt, kn, parent);
-               kernfs_addrm_finish(&acxt);
-               kernfs_put_active(parent);
-       }
-
+       error = kernfs_add_one(kn, parent);
        if (!error)
                return kn;
 

diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 61bd7ae6b8e0810a9b3f15620ba2df9e9f960f94..9b5a4bb88c6491909dfcbc1dde379cba954d2575 100644 (file)
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -89,10 +89,6 @@ struct kernfs_node {
 
        struct rb_node          rb;
 
-       union {
-               struct kernfs_node      *removed_list;
-       } u;
-
        const void              *ns;    /* namespace tag */
        unsigned int            hash;   /* ns + name hash */
        union {