1 files changed, 957 insertions, 340 deletions

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 85a668680f82..aee966c44aac 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -9,18 +9,346 @@
 #include <linux/module.h>
 #include <linux/kobject.h>
 #include <linux/namei.h>
+#include <linux/idr.h>
+#include <linux/completion.h>
 #include <asm/semaphore.h>
 #include "sysfs.h"
 
-DECLARE_RWSEM(sysfs_rename_sem);
+DEFINE_MUTEX(sysfs_mutex);
+spinlock_t sysfs_assoc_lock = SPIN_LOCK_UNLOCKED;
+
+static spinlock_t sysfs_ino_lock = SPIN_LOCK_UNLOCKED;
+static DEFINE_IDA(sysfs_ino_ida);
+
+/**
+ *      sysfs_link_sibling - link sysfs_dirent into sibling list
+ *      @sd: sysfs_dirent of interest
+ *
+ *      Link @sd into its sibling list which starts from
+ *      sd->s_parent->s_children.
+ *
+ *      Locking:
+ *      mutex_lock(sysfs_mutex)
+ */
+void sysfs_link_sibling(struct sysfs_dirent *sd)
+{
+        struct sysfs_dirent *parent_sd = sd->s_parent;
+
+        BUG_ON(sd->s_sibling);
+        sd->s_sibling = parent_sd->s_children;
+        parent_sd->s_children = sd;
+}
+
+/**
+ *      sysfs_unlink_sibling - unlink sysfs_dirent from sibling list
+ *      @sd: sysfs_dirent of interest
+ *
+ *      Unlink @sd from its sibling list which starts from
+ *      sd->s_parent->s_children.
+ *
+ *      Locking:
+ *      mutex_lock(sysfs_mutex)
+ */
+void sysfs_unlink_sibling(struct sysfs_dirent *sd)
+{
+        struct sysfs_dirent **pos;
+
+        for (pos = &sd->s_parent->s_children; *pos; pos = &(*pos)->s_sibling) {
+                if (*pos == sd) {
+                        *pos = sd->s_sibling;
+                        sd->s_sibling = NULL;
+                        break;
+                }
+        }
+}
+
+/**
+ *      sysfs_get_dentry - get dentry for the given sysfs_dirent
+ *      @sd: sysfs_dirent of interest
+ *
+ *      Get dentry for @sd.  Dentry is looked up if currently not
+ *      present.  This function climbs sysfs_dirent tree till it
+ *      reaches a sysfs_dirent with valid dentry attached and descends
+ *      down from there looking up dentry for each step.
+ *
+ *      LOCKING:
+ *      Kernel thread context (may sleep)
+ *
+ *      RETURNS:
+ *      Pointer to found dentry on success, ERR_PTR() value on error.
+ */
+struct dentry *sysfs_get_dentry(struct sysfs_dirent *sd)
+{
+        struct sysfs_dirent *cur;
+        struct dentry *parent_dentry, *dentry;
+        int i, depth;
+
+        /* Find the first parent which has valid s_dentry and get the
+         * dentry.
+         */
+        mutex_lock(&sysfs_mutex);
+ restart0:
+        spin_lock(&sysfs_assoc_lock);
+ restart1:
+        spin_lock(&dcache_lock);
+
+        dentry = NULL;
+        depth = 0;
+        cur = sd;
+        while (!cur->s_dentry || !cur->s_dentry->d_inode) {
+                if (cur->s_flags & SYSFS_FLAG_REMOVED) {
+                        dentry = ERR_PTR(-ENOENT);
+                        depth = 0;
+                        break;
+                }
+                cur = cur->s_parent;
+                depth++;
+        }
+        if (!IS_ERR(dentry))
+                dentry = dget_locked(cur->s_dentry);
+
+        spin_unlock(&dcache_lock);
+        spin_unlock(&sysfs_assoc_lock);
+
+        /* from the found dentry, look up depth times */
+        while (depth--) {
+                /* find and get depth'th ancestor */
+                for (cur = sd, i = 0; cur && i < depth; i++)
+                        cur = cur->s_parent;
+
+                /* This can happen if tree structure was modified due
+                 * to move/rename.  Restart.
+                 */
+                if (i != depth) {
+                        dput(dentry);
+                        goto restart0;
+                }
+
+                sysfs_get(cur);
+
+                mutex_unlock(&sysfs_mutex);
+
+                /* look it up */
+                parent_dentry = dentry;
+                dentry = lookup_one_len_kern(cur->s_name, parent_dentry,
+                                             strlen(cur->s_name));
+                dput(parent_dentry);
+
+                if (IS_ERR(dentry)) {
+                        sysfs_put(cur);
+                        return dentry;
+                }
+
+                mutex_lock(&sysfs_mutex);
+                spin_lock(&sysfs_assoc_lock);
+
+                /* This, again, can happen if tree structure has
+                 * changed and we looked up the wrong thing.  Restart.
+                 */
+                if (cur->s_dentry != dentry) {
+                        dput(dentry);
+                        sysfs_put(cur);
+                        goto restart1;
+                }
+
+                spin_unlock(&sysfs_assoc_lock);
+
+                sysfs_put(cur);
+        }
+
+        mutex_unlock(&sysfs_mutex);
+        return dentry;
+}
+
+/**
+ *      sysfs_get_active - get an active reference to sysfs_dirent
+ *      @sd: sysfs_dirent to get an active reference to
+ *
+ *      Get an active reference of @sd.  This function is noop if @sd
+ *      is NULL.
+ *
+ *      RETURNS:
+ *      Pointer to @sd on success, NULL on failure.
+ */
+struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd)
+{
+        if (unlikely(!sd))
+                return NULL;
+
+        while (1) {
+                int v, t;
+
+                v = atomic_read(&sd->s_active);
+                if (unlikely(v < 0))
+                        return NULL;
+
+                t = atomic_cmpxchg(&sd->s_active, v, v + 1);
+                if (likely(t == v))
+                        return sd;
+                if (t < 0)
+                        return NULL;
+
+                cpu_relax();
+        }
+}
+
+/**
+ *      sysfs_put_active - put an active reference to sysfs_dirent
+ *      @sd: sysfs_dirent to put an active reference to
+ *
+ *      Put an active reference to @sd.  This function is noop if @sd
+ *      is NULL.
+ */
+void sysfs_put_active(struct sysfs_dirent *sd)
+{
+        struct completion *cmpl;
+        int v;
+
+        if (unlikely(!sd))
+                return;
+
+        v = atomic_dec_return(&sd->s_active);
+        if (likely(v != SD_DEACTIVATED_BIAS))
+                return;
+
+        /* atomic_dec_return() is a mb(), we'll always see the updated
+         * sd->s_sibling.
+         */
+        cmpl = (void *)sd->s_sibling;
+        complete(cmpl);
+}
+
+/**
+ *      sysfs_get_active_two - get active references to sysfs_dirent and parent
+ *      @sd: sysfs_dirent of interest
+ *
+ *      Get active reference to @sd and its parent.  Parent's active
+ *      reference is grabbed first.  This function is noop if @sd is
+ *      NULL.
+ *
+ *      RETURNS:
+ *      Pointer to @sd on success, NULL on failure.
+ */
+struct sysfs_dirent *sysfs_get_active_two(struct sysfs_dirent *sd)
+{
+        if (sd) {
+                if (sd->s_parent && unlikely(!sysfs_get_active(sd->s_parent)))
+                        return NULL;
+                if (unlikely(!sysfs_get_active(sd))) {
+                        sysfs_put_active(sd->s_parent);
+                        return NULL;
+                }
+        }
+        return sd;
+}
+
+/**
+ *      sysfs_put_active_two - put active references to sysfs_dirent and parent
+ *      @sd: sysfs_dirent of interest
+ *
+ *      Put active references to @sd and its parent.  This function is
+ *      noop if @sd is NULL.
+ */
+void sysfs_put_active_two(struct sysfs_dirent *sd)
+{
+        if (sd) {
+                sysfs_put_active(sd);
+                sysfs_put_active(sd->s_parent);
+        }
+}
+
+/**
+ *      sysfs_deactivate - deactivate sysfs_dirent
+ *      @sd: sysfs_dirent to deactivate
+ *
+ *      Deny new active references and drain existing ones.
+ */
+static void sysfs_deactivate(struct sysfs_dirent *sd)
+{
+        DECLARE_COMPLETION_ONSTACK(wait);
+        int v;
+
+        BUG_ON(sd->s_sibling || !(sd->s_flags & SYSFS_FLAG_REMOVED));
+        sd->s_sibling = (void *)&wait;
+
+        /* atomic_add_return() is a mb(), put_active() will always see
+         * the updated sd->s_sibling.
+         */
+        v = atomic_add_return(SD_DEACTIVATED_BIAS, &sd->s_active);
+
+        if (v != SD_DEACTIVATED_BIAS)
+                wait_for_completion(&wait);
+
+        sd->s_sibling = NULL;
+}
+
+static int sysfs_alloc_ino(ino_t *pino)
+{
+        int ino, rc;
+
+ retry:
+        spin_lock(&sysfs_ino_lock);
+        rc = ida_get_new_above(&sysfs_ino_ida, 2, &ino);
+        spin_unlock(&sysfs_ino_lock);
+
+        if (rc == -EAGAIN) {
+                if (ida_pre_get(&sysfs_ino_ida, GFP_KERNEL))
+                        goto retry;
+                rc = -ENOMEM;
+        }
+
+        *pino = ino;
+        return rc;
+}
+
+static void sysfs_free_ino(ino_t ino)
+{
+        spin_lock(&sysfs_ino_lock);
+        ida_remove(&sysfs_ino_ida, ino);
+        spin_unlock(&sysfs_ino_lock);
+}
+
+void release_sysfs_dirent(struct sysfs_dirent * sd)
+{
+        struct sysfs_dirent *parent_sd;
+
+ repeat:
+        /* Moving/renaming is always done while holding reference.
+         * sd->s_parent won't change beneath us.
+         */
+        parent_sd = sd->s_parent;
+
+        if (sysfs_type(sd) == SYSFS_KOBJ_LINK)
+                sysfs_put(sd->s_elem.symlink.target_sd);
+        if (sysfs_type(sd) & SYSFS_COPY_NAME)
+                kfree(sd->s_name);
+        kfree(sd->s_iattr);
+        sysfs_free_ino(sd->s_ino);
+        kmem_cache_free(sysfs_dir_cachep, sd);
+
+        sd = parent_sd;
+        if (sd && atomic_dec_and_test(&sd->s_count))
+                goto repeat;
+}
 
 static void sysfs_d_iput(struct dentry * dentry, struct inode * inode)
 {
         struct sysfs_dirent * sd = dentry->d_fsdata;
 
         if (sd) {
-                BUG_ON(sd->s_dentry != dentry);
-                sd->s_dentry = NULL;
+                /* sd->s_dentry is protected with sysfs_assoc_lock.
+                 * This allows sysfs_drop_dentry() to dereference it.
+                 */
+                spin_lock(&sysfs_assoc_lock);
+
+                /* The dentry might have been deleted or another
+                 * lookup could have happened updating sd->s_dentry to
+                 * point the new dentry.  Ignore if it isn't pointing
+                 * to this dentry.
+                 */
+                if (sd->s_dentry == dentry)
+                        sd->s_dentry = NULL;
+                spin_unlock(&sysfs_assoc_lock);
                 sysfs_put(sd);
         }
         iput(inode);
@@ -30,245 +358,402 @@ static struct dentry_operations sysfs_dentry_ops = {
         .d_iput         = sysfs_d_iput,
 };
 
-/*
- * Allocates a new sysfs_dirent and links it to the parent sysfs_dirent
- */
-static struct sysfs_dirent * __sysfs_new_dirent(void * element)
+struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type)
 {
-        struct sysfs_dirent * sd;
+        char *dup_name = NULL;
+        struct sysfs_dirent *sd = NULL;
+
+        if (type & SYSFS_COPY_NAME) {
+                name = dup_name = kstrdup(name, GFP_KERNEL);
+                if (!name)
+                        goto err_out;
+        }
 
         sd = kmem_cache_zalloc(sysfs_dir_cachep, GFP_KERNEL);
         if (!sd)
-                return NULL;
+                goto err_out;
+
+        if (sysfs_alloc_ino(&sd->s_ino))
+                goto err_out;
 
         atomic_set(&sd->s_count, 1);
+        atomic_set(&sd->s_active, 0);
         atomic_set(&sd->s_event, 1);
-        INIT_LIST_HEAD(&sd->s_children);
-        INIT_LIST_HEAD(&sd->s_sibling);
-        sd->s_element = element;
+
+        sd->s_name = name;
+        sd->s_mode = mode;
+        sd->s_flags = type;
 
         return sd;
+
+ err_out:
+        kfree(dup_name);
+        kmem_cache_free(sysfs_dir_cachep, sd);
+        return NULL;
 }
 
-static void __sysfs_list_dirent(struct sysfs_dirent *parent_sd,
-                              struct sysfs_dirent *sd)
+/**
+ *      sysfs_attach_dentry - associate sysfs_dirent with dentry
+ *      @sd: target sysfs_dirent
+ *      @dentry: dentry to associate
+ *
+ *      Associate @sd with @dentry.  This is protected by
+ *      sysfs_assoc_lock to avoid race with sysfs_d_iput().
+ *
+ *      LOCKING:
+ *      mutex_lock(sysfs_mutex)
+ */
+static void sysfs_attach_dentry(struct sysfs_dirent *sd, struct dentry *dentry)
 {
-        if (sd)
-                list_add(&sd->s_sibling, &parent_sd->s_children);
+        dentry->d_op = &sysfs_dentry_ops;
+        dentry->d_fsdata = sysfs_get(sd);
+
+        /* protect sd->s_dentry against sysfs_d_iput */
+        spin_lock(&sysfs_assoc_lock);
+        sd->s_dentry = dentry;
+        spin_unlock(&sysfs_assoc_lock);
+
+        d_rehash(dentry);
 }
 
-static struct sysfs_dirent * sysfs_new_dirent(struct sysfs_dirent *parent_sd,
-                                                void * element)
+static int sysfs_ilookup_test(struct inode *inode, void *arg)
 {
-        struct sysfs_dirent *sd;
-        sd = __sysfs_new_dirent(element);
-        __sysfs_list_dirent(parent_sd, sd);
-        return sd;
+        struct sysfs_dirent *sd = arg;
+        return inode->i_ino == sd->s_ino;
 }
 
-/*
+/**
+ *      sysfs_addrm_start - prepare for sysfs_dirent add/remove
+ *      @acxt: pointer to sysfs_addrm_cxt to be used
+ *      @parent_sd: parent sysfs_dirent
  *
- * Return -EEXIST if there is already a sysfs element with the same name for
- * the same parent.
+ *      This function is called when the caller is about to add or
+ *      remove sysfs_dirent under @parent_sd.  This function acquires
+ *      sysfs_mutex, grabs inode for @parent_sd if available and lock
+ *      i_mutex of it.  @acxt is used to keep and pass context to
+ *      other addrm functions.
  *
- * called with parent inode's i_mutex held
+ *      LOCKING:
+ *      Kernel thread context (may sleep).  sysfs_mutex is locked on
+ *      return.  i_mutex of parent inode is locked on return if
+ *      available.
  */
-int sysfs_dirent_exist(struct sysfs_dirent *parent_sd,
-                          const unsigned char *new)
+void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt,
+                       struct sysfs_dirent *parent_sd)
 {
-        struct sysfs_dirent * sd;
+        struct inode *inode;
 
-        list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
-                if (sd->s_element) {
-                        const unsigned char *existing = sysfs_get_name(sd);
-                        if (strcmp(existing, new))
-                                continue;
-                        else
-                                return -EEXIST;
-                }
-        }
+        memset(acxt, 0, sizeof(*acxt));
+        acxt->parent_sd = parent_sd;
 
-        return 0;
+        /* Lookup parent inode.  inode initialization and I_NEW
+         * clearing are protected by sysfs_mutex.  By grabbing it and
+         * looking up with _nowait variant, inode state can be
+         * determined reliably.
+         */
+        mutex_lock(&sysfs_mutex);
+
+        inode = ilookup5_nowait(sysfs_sb, parent_sd->s_ino, sysfs_ilookup_test,
+                                parent_sd);
+
+        if (inode && !(inode->i_state & I_NEW)) {
+                /* parent inode available */
+                acxt->parent_inode = inode;
+
+                /* sysfs_mutex is below i_mutex in lock hierarchy.
+                 * First, trylock i_mutex.  If fails, unlock
+                 * sysfs_mutex and lock them in order.
+                 */
+                if (!mutex_trylock(&inode->i_mutex)) {
+                        mutex_unlock(&sysfs_mutex);
+                        mutex_lock(&inode->i_mutex);
+                        mutex_lock(&sysfs_mutex);
+                }
+        } else
+                iput(inode);
 }
 
+/**
+ *      sysfs_add_one - add sysfs_dirent to parent
+ *      @acxt: addrm context to use
+ *      @sd: sysfs_dirent to be added
+ *
+ *      Get @acxt->parent_sd and set sd->s_parent to it and increment
+ *      nlink of parent inode if @sd is a directory.  @sd is NOT
+ *      linked into the children list of the parent.  The caller
+ *      should invoke sysfs_link_sibling() after this function
+ *      completes if @sd needs to be on the children list.
+ *
+ *      This function should be called between calls to
+ *      sysfs_addrm_start() and sysfs_addrm_finish() and should be
+ *      passed the same @acxt as passed to sysfs_addrm_start().
+ *
+ *      LOCKING:
+ *      Determined by sysfs_addrm_start().
+ */
+void sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
+{
+        sd->s_parent = sysfs_get(acxt->parent_sd);
+
+        if (sysfs_type(sd) == SYSFS_DIR && acxt->parent_inode)
+                inc_nlink(acxt->parent_inode);
+
+        acxt->cnt++;
+}
 
-static struct sysfs_dirent *
-__sysfs_make_dirent(struct dentry *dentry, void *element, mode_t mode, int type)
+/**
+ *      sysfs_remove_one - remove sysfs_dirent from parent
+ *      @acxt: addrm context to use
+ *      @sd: sysfs_dirent to be added
+ *
+ *      Mark @sd removed and drop nlink of parent inode if @sd is a
+ *      directory.  @sd is NOT unlinked from the children list of the
+ *      parent.  The caller is repsonsible for removing @sd from the
+ *      children list before calling this function.
+ *
+ *      This function should be called between calls to
+ *      sysfs_addrm_start() and sysfs_addrm_finish() and should be
+ *      passed the same @acxt as passed to sysfs_addrm_start().
+ *
+ *      LOCKING:
+ *      Determined by sysfs_addrm_start().
+ */
+void sysfs_remove_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
 {
-        struct sysfs_dirent * sd;
+        BUG_ON(sd->s_sibling || (sd->s_flags & SYSFS_FLAG_REMOVED));
 
-        sd = __sysfs_new_dirent(element);
-        if (!sd)
-                goto out;
+        sd->s_flags |= SYSFS_FLAG_REMOVED;
+        sd->s_sibling = acxt->removed;
+        acxt->removed = sd;
 
-        sd->s_mode = mode;
-        sd->s_type = type;
-        sd->s_dentry = dentry;
-        if (dentry) {
-                dentry->d_fsdata = sysfs_get(sd);
-                dentry->d_op = &sysfs_dentry_ops;
-        }
+        if (sysfs_type(sd) == SYSFS_DIR && acxt->parent_inode)
+                drop_nlink(acxt->parent_inode);
 
-out:
-        return sd;
+        acxt->cnt++;
 }
 
-int sysfs_make_dirent(struct sysfs_dirent * parent_sd, struct dentry * dentry,
-                        void * element, umode_t mode, int type)
+/**
+ *      sysfs_drop_dentry - drop dentry for the specified sysfs_dirent
+ *      @sd: target sysfs_dirent
+ *
+ *      Drop dentry for @sd.  @sd must have been unlinked from its
+ *      parent on entry to this function such that it can't be looked
+ *      up anymore.
+ *
+ *      @sd->s_dentry which is protected with sysfs_assoc_lock points
+ *      to the currently associated dentry but we're not holding a
+ *      reference to it and racing with dput().  Grab dcache_lock and
+ *      verify dentry before dropping it.  If @sd->s_dentry is NULL or
+ *      dput() beats us, no need to bother.
+ */
+static void sysfs_drop_dentry(struct sysfs_dirent *sd)
 {
-        struct sysfs_dirent *sd;
+        struct dentry *dentry = NULL;
+        struct inode *inode;
+
+        /* We're not holding a reference to ->s_dentry dentry but the
+         * field will stay valid as long as sysfs_assoc_lock is held.
+         */
+        spin_lock(&sysfs_assoc_lock);
+        spin_lock(&dcache_lock);
+
+        /* drop dentry if it's there and dput() didn't kill it yet */
+        if (sd->s_dentry && sd->s_dentry->d_inode) {
+                dentry = dget_locked(sd->s_dentry);
+                spin_lock(&dentry->d_lock);
+                __d_drop(dentry);
+                spin_unlock(&dentry->d_lock);
+        }
 
-        sd = __sysfs_make_dirent(dentry, element, mode, type);
-        __sysfs_list_dirent(parent_sd, sd);
+        spin_unlock(&dcache_lock);
+        spin_unlock(&sysfs_assoc_lock);
 
-        return sd ? 0 : -ENOMEM;
+        /* dentries for shadowed inodes are pinned, unpin */
+        if (dentry && sysfs_is_shadowed_inode(dentry->d_inode))
+                dput(dentry);
+        dput(dentry);
+
+        /* adjust nlink and update timestamp */
+        inode = ilookup(sysfs_sb, sd->s_ino);
+        if (inode) {
+                mutex_lock(&inode->i_mutex);
+
+                inode->i_ctime = CURRENT_TIME;
+                drop_nlink(inode);
+                if (sysfs_type(sd) == SYSFS_DIR)
+                        drop_nlink(inode);
+
+                mutex_unlock(&inode->i_mutex);
+                iput(inode);
+        }
 }
 
-static int init_dir(struct inode * inode)
+/**
+ *      sysfs_addrm_finish - finish up sysfs_dirent add/remove
+ *      @acxt: addrm context to finish up
+ *
+ *      Finish up sysfs_dirent add/remove.  Resources acquired by
+ *      sysfs_addrm_start() are released and removed sysfs_dirents are
+ *      cleaned up.  Timestamps on the parent inode are updated.
+ *
+ *      LOCKING:
+ *      All mutexes acquired by sysfs_addrm_start() are released.
+ *
+ *      RETURNS:
+ *      Number of added/removed sysfs_dirents since sysfs_addrm_start().
+ */
+int sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt)
 {
-        inode->i_op = &sysfs_dir_inode_operations;
-        inode->i_fop = &sysfs_dir_operations;
+        /* release resources acquired by sysfs_addrm_start() */
+        mutex_unlock(&sysfs_mutex);
+        if (acxt->parent_inode) {
+                struct inode *inode = acxt->parent_inode;
 
-        /* directory inodes start off with i_nlink == 2 (for "." entry) */
-        inc_nlink(inode);
-        return 0;
+                /* if added/removed, update timestamps on the parent */
+                if (acxt->cnt)
+                        inode->i_ctime = inode->i_mtime = CURRENT_TIME;
+
+                mutex_unlock(&inode->i_mutex);
+                iput(inode);
+        }
+
+        /* kill removed sysfs_dirents */
+        while (acxt->removed) {
+                struct sysfs_dirent *sd = acxt->removed;
+
+                acxt->removed = sd->s_sibling;
+                sd->s_sibling = NULL;
+
+                sysfs_drop_dentry(sd);
+                sysfs_deactivate(sd);
+                sysfs_put(sd);
+        }
+
+        return acxt->cnt;
 }
 
-static int init_file(struct inode * inode)
+/**
+ *      sysfs_find_dirent - find sysfs_dirent with the given name
+ *      @parent_sd: sysfs_dirent to search under
+ *      @name: name to look for
+ *
+ *      Look for sysfs_dirent with name @name under @parent_sd.
+ *
+ *      LOCKING:
+ *      mutex_lock(sysfs_mutex)
+ *
+ *      RETURNS:
+ *      Pointer to sysfs_dirent if found, NULL if not.
+ */
+struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd,
+                                       const unsigned char *name)
 {
-        inode->i_size = PAGE_SIZE;
-        inode->i_fop = &sysfs_file_operations;
-        return 0;
+        struct sysfs_dirent *sd;
+
+        for (sd = parent_sd->s_children; sd; sd = sd->s_sibling)
+                if (sysfs_type(sd) && !strcmp(sd->s_name, name))
+                        return sd;
+        return NULL;
 }
 
-static int init_symlink(struct inode * inode)
+/**
+ *      sysfs_get_dirent - find and get sysfs_dirent with the given name
+ *      @parent_sd: sysfs_dirent to search under
+ *      @name: name to look for
+ *
+ *      Look for sysfs_dirent with name @name under @parent_sd and get
+ *      it if found.
+ *
+ *      LOCKING:
+ *      Kernel thread context (may sleep).  Grabs sysfs_mutex.
+ *
+ *      RETURNS:
+ *      Pointer to sysfs_dirent if found, NULL if not.
+ */
+struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd,
+                                      const unsigned char *name)
 {
-        inode->i_op = &sysfs_symlink_inode_operations;
-        return 0;
+        struct sysfs_dirent *sd;
+
+        mutex_lock(&sysfs_mutex);
+        sd = sysfs_find_dirent(parent_sd, name);
+        sysfs_get(sd);
+        mutex_unlock(&sysfs_mutex);
+
+        return sd;
 }
 
-static int create_dir(struct kobject * k, struct dentry * p,
-                      const char * n, struct dentry ** d)
+static int create_dir(struct kobject *kobj, struct sysfs_dirent *parent_sd,
+                      const char *name, struct sysfs_dirent **p_sd)
 {
-        int error;
         umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
+        struct sysfs_addrm_cxt acxt;
+        struct sysfs_dirent *sd;
 
-        mutex_lock(&p->d_inode->i_mutex);
-        *d = lookup_one_len(n, p, strlen(n));
-        if (!IS_ERR(*d)) {
-                if (sysfs_dirent_exist(p->d_fsdata, n))
-                        error = -EEXIST;
-                else
-                        error = sysfs_make_dirent(p->d_fsdata, *d, k, mode,
-                                                                SYSFS_DIR);
-                if (!error) {
-                        error = sysfs_create(*d, mode, init_dir);
-                        if (!error) {
-                                inc_nlink(p->d_inode);
-                                (*d)->d_op = &sysfs_dentry_ops;
-                                d_rehash(*d);
-                        }
-                }
-                if (error && (error != -EEXIST)) {
-                        struct sysfs_dirent *sd = (*d)->d_fsdata;
-                        if (sd) {
-                                list_del_init(&sd->s_sibling);
-                                sysfs_put(sd);
-                        }
-                        d_drop(*d);
-                }
-                dput(*d);
-        } else
-                error = PTR_ERR(*d);
-        mutex_unlock(&p->d_inode->i_mutex);
-        return error;
-}
+        /* allocate */
+        sd = sysfs_new_dirent(name, mode, SYSFS_DIR);
+        if (!sd)
+                return -ENOMEM;
+        sd->s_elem.dir.kobj = kobj;
 
+        /* link in */
+        sysfs_addrm_start(&acxt, parent_sd);
+        if (!sysfs_find_dirent(parent_sd, name)) {
+                sysfs_add_one(&acxt, sd);
+                sysfs_link_sibling(sd);
+        }
+        if (sysfs_addrm_finish(&acxt)) {
+                *p_sd = sd;
+                return 0;
+        }
 
-int sysfs_create_subdir(struct kobject * k, const char * n, struct dentry ** d)
+        sysfs_put(sd);
+        return -EEXIST;
+}
+
+int sysfs_create_subdir(struct kobject *kobj, const char *name,
+                        struct sysfs_dirent **p_sd)
 {
-        return create_dir(k,k->dentry,n,d);
+        return create_dir(kobj, kobj->sd, name, p_sd);
 }
 
 /**
  *      sysfs_create_dir - create a directory for an object.
  *      @kobj:          object we're creating directory for. 
- *      @shadow_parent: parent parent object.
+ *      @shadow_parent: parent object.
  */
-
-int sysfs_create_dir(struct kobject * kobj, struct dentry *shadow_parent)
+int sysfs_create_dir(struct kobject *kobj,
+                     struct sysfs_dirent *shadow_parent_sd)
 {
-        struct dentry * dentry = NULL;
-        struct dentry * parent;
+        struct sysfs_dirent *parent_sd, *sd;
         int error = 0;
 
         BUG_ON(!kobj);
 
-        if (shadow_parent)
-                parent = shadow_parent;
+        if (shadow_parent_sd)
+                parent_sd = shadow_parent_sd;
         else if (kobj->parent)
-                parent = kobj->parent->dentry;
+                parent_sd = kobj->parent->sd;
         else if (sysfs_mount && sysfs_mount->mnt_sb)
-                parent = sysfs_mount->mnt_sb->s_root;
+                parent_sd = sysfs_mount->mnt_sb->s_root->d_fsdata;
         else
                 return -EFAULT;
 
-        error = create_dir(kobj,parent,kobject_name(kobj),&dentry);
+        error = create_dir(kobj, parent_sd, kobject_name(kobj), &sd);
         if (!error)
-                kobj->dentry = dentry;
+                kobj->sd = sd;
         return error;
 }
 
-/* attaches attribute's sysfs_dirent to the dentry corresponding to the
- * attribute file
- */
-static int sysfs_attach_attr(struct sysfs_dirent * sd, struct dentry * dentry)
+static int sysfs_count_nlink(struct sysfs_dirent *sd)
 {
-        struct attribute * attr = NULL;
-        struct bin_attribute * bin_attr = NULL;
-        int (* init) (struct inode *) = NULL;
-        int error = 0;
+        struct sysfs_dirent *child;
+        int nr = 0;
 
-        if (sd->s_type & SYSFS_KOBJ_BIN_ATTR) {
-                bin_attr = sd->s_element;
-                attr = &bin_attr->attr;
-        } else {
-                attr = sd->s_element;
-                init = init_file;
-        }
-
-        dentry->d_fsdata = sysfs_get(sd);
-        sd->s_dentry = dentry;
-        error = sysfs_create(dentry, (attr->mode & S_IALLUGO) | S_IFREG, init);
-        if (error) {
-                sysfs_put(sd);
-                return error;
-        }
-
-        if (bin_attr) {
-                dentry->d_inode->i_size = bin_attr->size;
-                dentry->d_inode->i_fop = &bin_fops;
-        }
-        dentry->d_op = &sysfs_dentry_ops;
-        d_rehash(dentry);
-
-        return 0;
-}
-
-static int sysfs_attach_link(struct sysfs_dirent * sd, struct dentry * dentry)
-{
-        int err = 0;
-
-        dentry->d_fsdata = sysfs_get(sd);
-        sd->s_dentry = dentry;
-        err = sysfs_create(dentry, S_IFLNK|S_IRWXUGO, init_symlink);
-        if (!err) {
-                dentry->d_op = &sysfs_dentry_ops;
-                d_rehash(dentry);
-        } else
-                sysfs_put(sd);
-
-        return err;
+        for (child = sd->s_children; child; child = child->s_sibling)
+                if (sysfs_type(child) == SYSFS_DIR)
+                        nr++;
+        return nr + 2;
 }
 
 static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry,
@@ -276,24 +761,60 @@ static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry,
 {
         struct sysfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
         struct sysfs_dirent * sd;
-        int err = 0;
+        struct bin_attribute *bin_attr;
+        struct inode *inode;
+        int found = 0;
 
-        list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
-                if (sd->s_type & SYSFS_NOT_PINNED) {
-                        const unsigned char * name = sysfs_get_name(sd);
+        for (sd = parent_sd->s_children; sd; sd = sd->s_sibling) {
+                if (sysfs_type(sd) &&
+                    !strcmp(sd->s_name, dentry->d_name.name)) {
+                        found = 1;
+                        break;
+                }
+        }
+
+        /* no such entry */
+        if (!found)
+                return NULL;
 
-                        if (strcmp(name, dentry->d_name.name))
-                                continue;
+        /* attach dentry and inode */
+        inode = sysfs_get_inode(sd);
+        if (!inode)
+                return ERR_PTR(-ENOMEM);
 
-                        if (sd->s_type & SYSFS_KOBJ_LINK)
-                                err = sysfs_attach_link(sd, dentry);
-                        else
-                                err = sysfs_attach_attr(sd, dentry);
+        mutex_lock(&sysfs_mutex);
+
+        if (inode->i_state & I_NEW) {
+                /* initialize inode according to type */
+                switch (sysfs_type(sd)) {
+                case SYSFS_DIR:
+                        inode->i_op = &sysfs_dir_inode_operations;
+                        inode->i_fop = &sysfs_dir_operations;
+                        inode->i_nlink = sysfs_count_nlink(sd);
                         break;
+                case SYSFS_KOBJ_ATTR:
+                        inode->i_size = PAGE_SIZE;
+                        inode->i_fop = &sysfs_file_operations;
+                        break;
+                case SYSFS_KOBJ_BIN_ATTR:
+                        bin_attr = sd->s_elem.bin_attr.bin_attr;
+                        inode->i_size = bin_attr->size;
+                        inode->i_fop = &bin_fops;
+                        break;
+                case SYSFS_KOBJ_LINK:
+                        inode->i_op = &sysfs_symlink_inode_operations;
+                        break;
+                default:
+                        BUG();
                 }
         }
 
-        return ERR_PTR(err);
+        sysfs_instantiate(dentry, inode);
+        sysfs_attach_dentry(sd, dentry);
+
+        mutex_unlock(&sysfs_mutex);
+
+        return NULL;
 }
 
 const struct inode_operations sysfs_dir_inode_operations = {
@@ -301,58 +822,46 @@ const struct inode_operations sysfs_dir_inode_operations = {
         .setattr        = sysfs_setattr,
 };
 
-static void remove_dir(struct dentry * d)
+static void remove_dir(struct sysfs_dirent *sd)
 {
-        struct dentry * parent = dget(d->d_parent);
-        struct sysfs_dirent * sd;
-
-        mutex_lock(&parent->d_inode->i_mutex);
-        d_delete(d);
-        sd = d->d_fsdata;
-        list_del_init(&sd->s_sibling);
-        sysfs_put(sd);
-        if (d->d_inode)
-                simple_rmdir(parent->d_inode,d);
+        struct sysfs_addrm_cxt acxt;
 
-        pr_debug(" o %s removing done (%d)\n",d->d_name.name,
-                 atomic_read(&d->d_count));
-
-        mutex_unlock(&parent->d_inode->i_mutex);
-        dput(parent);
+        sysfs_addrm_start(&acxt, sd->s_parent);
+        sysfs_unlink_sibling(sd);
+        sysfs_remove_one(&acxt, sd);
+        sysfs_addrm_finish(&acxt);
 }
 
-void sysfs_remove_subdir(struct dentry * d)
+void sysfs_remove_subdir(struct sysfs_dirent *sd)
 {
-        remove_dir(d);
+        remove_dir(sd);
 }
 
 
-static void __sysfs_remove_dir(struct dentry *dentry)
+static void __sysfs_remove_dir(struct sysfs_dirent *dir_sd)
 {
-        struct sysfs_dirent * parent_sd;
-        struct sysfs_dirent * sd, * tmp;
+        struct sysfs_addrm_cxt acxt;
+        struct sysfs_dirent **pos;
 
-        dget(dentry);
-        if (!dentry)
+        if (!dir_sd)
                 return;
 
-        pr_debug("sysfs %s: removing dir\n",dentry->d_name.name);
-        mutex_lock(&dentry->d_inode->i_mutex);
-        parent_sd = dentry->d_fsdata;
-        list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
-                if (!sd->s_element || !(sd->s_type & SYSFS_NOT_PINNED))
-                        continue;
-                list_del_init(&sd->s_sibling);
-                sysfs_drop_dentry(sd, dentry);
-                sysfs_put(sd);
+        pr_debug("sysfs %s: removing dir\n", dir_sd->s_name);
+        sysfs_addrm_start(&acxt, dir_sd);
+        pos = &dir_sd->s_children;
+        while (*pos) {
+                struct sysfs_dirent *sd = *pos;
+
+                if (sysfs_type(sd) && sysfs_type(sd) != SYSFS_DIR) {
+                        *pos = sd->s_sibling;
+                        sd->s_sibling = NULL;
+                        sysfs_remove_one(&acxt, sd);
+                } else
+                        pos = &(*pos)->s_sibling;
         }
-        mutex_unlock(&dentry->d_inode->i_mutex);
+        sysfs_addrm_finish(&acxt);
 
-        remove_dir(dentry);
-        /**
-         * Drop reference from dget() on entrance.
-         */
-        dput(dentry);
+        remove_dir(dir_sd);
 }
 
 /**
@@ -366,102 +875,166 @@ static void __sysfs_remove_dir(struct dentry *dentry)
 
 void sysfs_remove_dir(struct kobject * kobj)
 {
-        __sysfs_remove_dir(kobj->dentry);
-        kobj->dentry = NULL;
+        struct sysfs_dirent *sd = kobj->sd;
+
+        spin_lock(&sysfs_assoc_lock);
+        kobj->sd = NULL;
+        spin_unlock(&sysfs_assoc_lock);
+
+        __sysfs_remove_dir(sd);
 }
 
-int sysfs_rename_dir(struct kobject * kobj, struct dentry *new_parent,
+int sysfs_rename_dir(struct kobject *kobj, struct sysfs_dirent *new_parent_sd,
                      const char *new_name)
 {
-        int error = 0;
-        struct dentry * new_dentry;
+        struct sysfs_dirent *sd = kobj->sd;
+        struct dentry *new_parent = NULL;
+        struct dentry *old_dentry = NULL, *new_dentry = NULL;
+        const char *dup_name = NULL;
+        int error;
 
-        if (!new_parent)
-                return -EFAULT;
+        /* get dentries */
+        old_dentry = sysfs_get_dentry(sd);
+        if (IS_ERR(old_dentry)) {
+                error = PTR_ERR(old_dentry);
+                goto out_dput;
+        }
+
+        new_parent = sysfs_get_dentry(new_parent_sd);
+        if (IS_ERR(new_parent)) {
+                error = PTR_ERR(new_parent);
+                goto out_dput;
+        }
 
-        down_write(&sysfs_rename_sem);
+        /* lock new_parent and get dentry for new name */
         mutex_lock(&new_parent->d_inode->i_mutex);
 
         new_dentry = lookup_one_len(new_name, new_parent, strlen(new_name));
-        if (!IS_ERR(new_dentry)) {
-                /* By allowing two different directories with the
-                 * same d_parent we allow this routine to move
-                 * between different shadows of the same directory
-                 */
-                if (kobj->dentry->d_parent->d_inode != new_parent->d_inode)
-                        return -EINVAL;
-                else if (new_dentry->d_parent->d_inode != new_parent->d_inode)
-                        error = -EINVAL;
-                else if (new_dentry == kobj->dentry)
-                        error = -EINVAL;
-                else if (!new_dentry->d_inode) {
-                        error = kobject_set_name(kobj, "%s", new_name);
-                        if (!error) {
-                                struct sysfs_dirent *sd, *parent_sd;
-
-                                d_add(new_dentry, NULL);
-                                d_move(kobj->dentry, new_dentry);
-
-                                sd = kobj->dentry->d_fsdata;
-                                parent_sd = new_parent->d_fsdata;
-
-                                list_del_init(&sd->s_sibling);
-                                list_add(&sd->s_sibling, &parent_sd->s_children);
-                        }
-                        else
-                                d_drop(new_dentry);
-                } else
-                        error = -EEXIST;
-                dput(new_dentry);
+        if (IS_ERR(new_dentry)) {
+                error = PTR_ERR(new_dentry);
+                goto out_unlock;
         }
-        mutex_unlock(&new_parent->d_inode->i_mutex);
-        up_write(&sysfs_rename_sem);
 
+        /* By allowing two different directories with the same
+         * d_parent we allow this routine to move between different
+         * shadows of the same directory
+         */
+        error = -EINVAL;
+        if (old_dentry->d_parent->d_inode != new_parent->d_inode ||
+            new_dentry->d_parent->d_inode != new_parent->d_inode ||
+            old_dentry == new_dentry)
+                goto out_unlock;
+
+        error = -EEXIST;
+        if (new_dentry->d_inode)
+                goto out_unlock;
+
+        /* rename kobject and sysfs_dirent */
+        error = -ENOMEM;
+        new_name = dup_name = kstrdup(new_name, GFP_KERNEL);
+        if (!new_name)
+                goto out_drop;
+
+        error = kobject_set_name(kobj, "%s", new_name);
+        if (error)
+                goto out_drop;
+
+        dup_name = sd->s_name;
+        sd->s_name = new_name;
+
+        /* move under the new parent */
+        d_add(new_dentry, NULL);
+        d_move(sd->s_dentry, new_dentry);
+
+        mutex_lock(&sysfs_mutex);
+
+        sysfs_unlink_sibling(sd);
+        sysfs_get(new_parent_sd);
+        sysfs_put(sd->s_parent);
+        sd->s_parent = new_parent_sd;
+        sysfs_link_sibling(sd);
+
+        mutex_unlock(&sysfs_mutex);
+
+        error = 0;
+        goto out_unlock;
+
+ out_drop:
+        d_drop(new_dentry);
+ out_unlock:
+        mutex_unlock(&new_parent->d_inode->i_mutex);
+ out_dput:
+        kfree(dup_name);
+        dput(new_parent);
+        dput(old_dentry);
+        dput(new_dentry);
         return error;
 }
 
-int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent)
+int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent_kobj)
 {
-        struct dentry *old_parent_dentry, *new_parent_dentry, *new_dentry;
-        struct sysfs_dirent *new_parent_sd, *sd;
+        struct sysfs_dirent *sd = kobj->sd;
+        struct sysfs_dirent *new_parent_sd;
+        struct dentry *old_parent, *new_parent = NULL;
+        struct dentry *old_dentry = NULL, *new_dentry = NULL;
         int error;
 
-        old_parent_dentry = kobj->parent ?
-                kobj->parent->dentry : sysfs_mount->mnt_sb->s_root;
-        new_parent_dentry = new_parent ?
-                new_parent->dentry : sysfs_mount->mnt_sb->s_root;
+        BUG_ON(!sd->s_parent);
+        new_parent_sd = new_parent_kobj->sd ? new_parent_kobj->sd : &sysfs_root;
+
+        /* get dentries */
+        old_dentry = sysfs_get_dentry(sd);
+        if (IS_ERR(old_dentry)) {
+                error = PTR_ERR(old_dentry);
+                goto out_dput;
+        }
+        old_parent = sd->s_parent->s_dentry;
+
+        new_parent = sysfs_get_dentry(new_parent_sd);
+        if (IS_ERR(new_parent)) {
+                error = PTR_ERR(new_parent);
+                goto out_dput;
+        }
 
-        if (old_parent_dentry->d_inode == new_parent_dentry->d_inode)
-                return 0;       /* nothing to move */
+        if (old_parent->d_inode == new_parent->d_inode) {
+                error = 0;
+                goto out_dput;  /* nothing to move */
+        }
 again:
-        mutex_lock(&old_parent_dentry->d_inode->i_mutex);
-        if (!mutex_trylock(&new_parent_dentry->d_inode->i_mutex)) {
-                mutex_unlock(&old_parent_dentry->d_inode->i_mutex);
+        mutex_lock(&old_parent->d_inode->i_mutex);
+        if (!mutex_trylock(&new_parent->d_inode->i_mutex)) {
+                mutex_unlock(&old_parent->d_inode->i_mutex);
                 goto again;
         }
 
-        new_parent_sd = new_parent_dentry->d_fsdata;
-        sd = kobj->dentry->d_fsdata;
-
-        new_dentry = lookup_one_len(kobj->name, new_parent_dentry,
-                                    strlen(kobj->name));
+        new_dentry = lookup_one_len(kobj->name, new_parent, strlen(kobj->name));
         if (IS_ERR(new_dentry)) {
                 error = PTR_ERR(new_dentry);
-                goto out;
+                goto out_unlock;
         } else
                 error = 0;
         d_add(new_dentry, NULL);
-        d_move(kobj->dentry, new_dentry);
+        d_move(sd->s_dentry, new_dentry);
         dput(new_dentry);
 
         /* Remove from old parent's list and insert into new parent's list. */
-        list_del_init(&sd->s_sibling);
-        list_add(&sd->s_sibling, &new_parent_sd->s_children);
+        mutex_lock(&sysfs_mutex);
 
-out:
-        mutex_unlock(&new_parent_dentry->d_inode->i_mutex);
-        mutex_unlock(&old_parent_dentry->d_inode->i_mutex);
+        sysfs_unlink_sibling(sd);
+        sysfs_get(new_parent_sd);
+        sysfs_put(sd->s_parent);
+        sd->s_parent = new_parent_sd;
+        sysfs_link_sibling(sd);
 
+        mutex_unlock(&sysfs_mutex);
+
+ out_unlock:
+        mutex_unlock(&new_parent->d_inode->i_mutex);
+        mutex_unlock(&old_parent->d_inode->i_mutex);
+ out_dput:
+        dput(new_parent);
+        dput(old_dentry);
+        dput(new_dentry);
         return error;
 }
 
@@ -469,23 +1042,27 @@ static int sysfs_dir_open(struct inode *inode, struct file *file)
 {
         struct dentry * dentry = file->f_path.dentry;
         struct sysfs_dirent * parent_sd = dentry->d_fsdata;
+        struct sysfs_dirent * sd;
 
-        mutex_lock(&dentry->d_inode->i_mutex);
-        file->private_data = sysfs_new_dirent(parent_sd, NULL);
-        mutex_unlock(&dentry->d_inode->i_mutex);
-
-        return file->private_data ? 0 : -ENOMEM;
+        sd = sysfs_new_dirent("_DIR_", 0, 0);
+        if (sd) {
+                mutex_lock(&sysfs_mutex);
+                sd->s_parent = sysfs_get(parent_sd);
+                sysfs_link_sibling(sd);
+                mutex_unlock(&sysfs_mutex);
+        }
 
+        file->private_data = sd;
+        return sd ? 0 : -ENOMEM;
 }
 
 static int sysfs_dir_close(struct inode *inode, struct file *file)
 {
-        struct dentry * dentry = file->f_path.dentry;
         struct sysfs_dirent * cursor = file->private_data;
 
-        mutex_lock(&dentry->d_inode->i_mutex);
-        list_del_init(&cursor->s_sibling);
-        mutex_unlock(&dentry->d_inode->i_mutex);
+        mutex_lock(&sysfs_mutex);
+        sysfs_unlink_sibling(cursor);
+        mutex_unlock(&sysfs_mutex);
 
         release_sysfs_dirent(cursor);
 
@@ -503,54 +1080,65 @@ static int sysfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
         struct dentry *dentry = filp->f_path.dentry;
         struct sysfs_dirent * parent_sd = dentry->d_fsdata;
         struct sysfs_dirent *cursor = filp->private_data;
-        struct list_head *p, *q = &cursor->s_sibling;
+        struct sysfs_dirent **pos;
         ino_t ino;
         int i = filp->f_pos;
 
         switch (i) {
                 case 0:
-                        ino = dentry->d_inode->i_ino;
+                        ino = parent_sd->s_ino;
                         if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
                                 break;
                         filp->f_pos++;
                         i++;
                         /* fallthrough */
                 case 1:
-                        ino = parent_ino(dentry);
+                        if (parent_sd->s_parent)
+                                ino = parent_sd->s_parent->s_ino;
+                        else
+                                ino = parent_sd->s_ino;
                         if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
                                 break;
                         filp->f_pos++;
                         i++;
                         /* fallthrough */
                 default:
+                        mutex_lock(&sysfs_mutex);
+
+                        pos = &parent_sd->s_children;
+                        while (*pos != cursor)
+                                pos = &(*pos)->s_sibling;
+
+                        /* unlink cursor */
+                        *pos = cursor->s_sibling;
+
                         if (filp->f_pos == 2)
-                                list_move(q, &parent_sd->s_children);
+                                pos = &parent_sd->s_children;
 
-                        for (p=q->next; p!= &parent_sd->s_children; p=p->next) {
-                                struct sysfs_dirent *next;
+                        for ( ; *pos; pos = &(*pos)->s_sibling) {
+                                struct sysfs_dirent *next = *pos;
                                 const char * name;
                                 int len;
 
-                                next = list_entry(p, struct sysfs_dirent,
-                                                   s_sibling);
-                                if (!next->s_element)
+                                if (!sysfs_type(next))
                                         continue;
 
-                                name = sysfs_get_name(next);
+                                name = next->s_name;
                                 len = strlen(name);
-                                if (next->s_dentry)
-                                        ino = next->s_dentry->d_inode->i_ino;
-                                else
-                                        ino = iunique(sysfs_sb, 2);
+                                ino = next->s_ino;
 
                                 if (filldir(dirent, name, len, filp->f_pos, ino,
                                                  dt_type(next)) < 0)
-                                        return 0;
+                                        break;
 
-                                list_move(q, p);
-                                p = q;
                                 filp->f_pos++;
                         }
+
+                        /* put cursor back in */
+                        cursor->s_sibling = *pos;
+                        *pos = cursor;
+
+                        mutex_unlock(&sysfs_mutex);
         }
         return 0;
 }
@@ -559,7 +1147,6 @@ static loff_t sysfs_dir_lseek(struct file * file, loff_t offset, int origin)
 {
         struct dentry * dentry = file->f_path.dentry;
 
-        mutex_lock(&dentry->d_inode->i_mutex);
         switch (origin) {
                 case 1:
                         offset += file->f_pos;
@@ -567,31 +1154,35 @@ static loff_t sysfs_dir_lseek(struct file * file, loff_t offset, int origin)
                         if (offset >= 0)
                                 break;
                 default:
-                        mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
                         return -EINVAL;
         }
         if (offset != file->f_pos) {
+                mutex_lock(&sysfs_mutex);
+
                 file->f_pos = offset;
                 if (file->f_pos >= 2) {
                         struct sysfs_dirent *sd = dentry->d_fsdata;
                         struct sysfs_dirent *cursor = file->private_data;
-                        struct list_head *p;
+                        struct sysfs_dirent **pos;
                         loff_t n = file->f_pos - 2;
 
-                        list_del(&cursor->s_sibling);
-                        p = sd->s_children.next;
-                        while (n && p != &sd->s_children) {
-                                struct sysfs_dirent *next;
-                                next = list_entry(p, struct sysfs_dirent,
-                                                   s_sibling);
-                                if (next->s_element)
+                        sysfs_unlink_sibling(cursor);
+
+                        pos = &sd->s_children;
+                        while (n && *pos) {
+                                struct sysfs_dirent *next = *pos;
+                                if (sysfs_type(next))
                                         n--;
-                                p = p->next;
+                                pos = &(*pos)->s_sibling;
                         }
-                        list_add_tail(&cursor->s_sibling, p);
+
+                        cursor->s_sibling = *pos;
+                        *pos = cursor;
                 }
+
+                mutex_unlock(&sysfs_mutex);
         }
-        mutex_unlock(&dentry->d_inode->i_mutex);
+
         return offset;
 }
 
@@ -604,12 +1195,20 @@ static loff_t sysfs_dir_lseek(struct file * file, loff_t offset, int origin)
 int sysfs_make_shadowed_dir(struct kobject *kobj,
         void * (*follow_link)(struct dentry *, struct nameidata *))
 {
+        struct dentry *dentry;
         struct inode *inode;
         struct inode_operations *i_op;
 
-        inode = kobj->dentry->d_inode;
-        if (inode->i_op != &sysfs_dir_inode_operations)
+        /* get dentry for @kobj->sd, dentry of a shadowed dir is pinned */
+        dentry = sysfs_get_dentry(kobj->sd);
+        if (IS_ERR(dentry))
+                return PTR_ERR(dentry);
+
+        inode = dentry->d_inode;
+        if (inode->i_op != &sysfs_dir_inode_operations) {
+                dput(dentry);
                 return -EINVAL;
+        }
 
         i_op = kmalloc(sizeof(*i_op), GFP_KERNEL);
         if (!i_op)
@@ -634,54 +1233,72 @@ int sysfs_make_shadowed_dir(struct kobject *kobj,
  *      directory.
  */
 
-struct dentry *sysfs_create_shadow_dir(struct kobject *kobj)
+struct sysfs_dirent *sysfs_create_shadow_dir(struct kobject *kobj)
 {
-        struct sysfs_dirent *sd;
-        struct dentry *parent, *dir, *shadow;
+        struct sysfs_dirent *parent_sd = kobj->sd->s_parent;
+        struct dentry *dir, *parent, *shadow;
         struct inode *inode;
+        struct sysfs_dirent *sd;
+        struct sysfs_addrm_cxt acxt;
 
-        dir = kobj->dentry;
-        inode = dir->d_inode;
+        dir = sysfs_get_dentry(kobj->sd);
+        if (IS_ERR(dir)) {
+                sd = (void *)dir;
+                goto out;
+        }
         parent = dir->d_parent;
-        shadow = ERR_PTR(-EINVAL);
+
+        inode = dir->d_inode;
+        sd = ERR_PTR(-EINVAL);
         if (!sysfs_is_shadowed_inode(inode))
-                goto out;
+                goto out_dput;
 
         shadow = d_alloc(parent, &dir->d_name);
         if (!shadow)
                 goto nomem;
 
-        sd = __sysfs_make_dirent(shadow, kobj, inode->i_mode, SYSFS_DIR);
+        sd = sysfs_new_dirent("_SHADOW_", inode->i_mode, SYSFS_DIR);
         if (!sd)
                 goto nomem;
+        sd->s_elem.dir.kobj = kobj;
 
+        sysfs_addrm_start(&acxt, parent_sd);
+
+        /* add but don't link into children list */
+        sysfs_add_one(&acxt, sd);
+
+        /* attach and instantiate dentry */
+        sysfs_attach_dentry(sd, shadow);
         d_instantiate(shadow, igrab(inode));
-        inc_nlink(inode);
-        inc_nlink(parent->d_inode);
-        shadow->d_op = &sysfs_dentry_ops;
+        inc_nlink(inode);       /* tj: synchronization? */
+
+        sysfs_addrm_finish(&acxt);
 
         dget(shadow);           /* Extra count - pin the dentry in core */
 
-out:
-        return shadow;
-nomem:
+        goto out_dput;
+
+ nomem:
         dput(shadow);
-        shadow = ERR_PTR(-ENOMEM);
-        goto out;
+        sd = ERR_PTR(-ENOMEM);
+ out_dput:
+        dput(dir);
+ out:
+        return sd;
 }
 
 /**
  *      sysfs_remove_shadow_dir - remove an object's directory.
- *      @shadow: dentry of shadow directory
+ *      @shadow_sd: sysfs_dirent of shadow directory
  *
  *      The only thing special about this is that we remove any files in
  *      the directory before we remove the directory, and we've inlined
  *      what used to be sysfs_rmdir() below, instead of calling separately.
  */
 
-void sysfs_remove_shadow_dir(struct dentry *shadow)
+void sysfs_remove_shadow_dir(struct sysfs_dirent *shadow_sd)
 {
-        __sysfs_remove_dir(shadow);
+        __sysfs_remove_dir(shadow_sd);
 }
 
 const struct file_operations sysfs_dir_operations = {