Re: [PATCH 3.18 15/19] move d_rcu from overlapping d_child to overlapping d_alias

[Josh Boyer]

On Mon, Dec 15, 2014 at 04:44:35PM -0500, Josh Boyer wrote:
>On Mon, Dec 15, 2014 at 4:34 PM, Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote:
>> On Mon, Dec 15, 2014 at 04:21:12PM -0500, Josh Boyer wrote:
>>> On Mon, Dec 15, 2014 at 11:38 AM, Josh Boyer <jwboyer@xxxxxxxxxxxxxxxxx> wrote:
>>> > On Mon, Dec 15, 2014 at 11:34 AM, Greg Kroah-Hartman
>>> > <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
>>> >> On Mon, Dec 15, 2014 at 10:46:50AM -0500, Josh Boyer wrote:
>>> >>> On Sun, Dec 14, 2014 at 12:21:26PM -0800, Greg Kroah-Hartman wrote:
>>> >>> >3.18-stable review patch.  If anyone has any objections, please let me know.
>>> >>> >
>>> >>> >------------------
>>> >>> >
>>> >>> >From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
>>> >>> >
>>> >>> >commit 946e51f2bf37f1656916eb75bd0742ba33983c28 upstream.
>>> >>> >
>>> >>> >Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
>>> >>> >Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
>>> >>>
>>> >>> I noticed you don't have this (and the child commit) queued for 3.17.y.
>>> >>
>>> >> That is because:
>>> >>
>>> >>> The backport wasn't exactly straight-forward because of the d_external
>>> >>> stuff, but I took a swing at it.  After that, the other commit was a
>>> >>> quick cherry-pick.
>>> >>
>>> >> It wasn't a "simple" backport, and I didn't have the time.  I'm also
>>> >> going to drop 3.17 real-soon-now.
>>> >
>>> > Right, figured.  Fedora isn't going to rebase the stable releases to
>>> > 3.18 until 3.18.2-ish, and this fixes an issue so I thought I'd give
>>> > it a try.
>>> >
>>> >>> Al, does the below look correct for a backport on top of 3.17.6?  It
>>> >>> builds, but I haven't tested it yet.
>>> >>
>>> >> Testing would be great to do :)
>>> >
>>> > Working on it.  Just wanted to send it out early in case Al spotted
>>> > something obviously wrong and wanted to yell at me for it.
>>>
>>> Finally got around to booting it.  Something is definitely wrong.  Sigh.
>>
>> Start with moving WARN_ON() into dentry_free() (as it's done in mainline and
>> for the same reason)...
>
>Gah, yes.  I'd just gotten to that hunk and realized it looked really
>really wrong.  I'll give that a shot.

OK, that seems to be much better.  It boots in a guest and things seem
to be operating fine in a light touch test.  I'll keep testing it today.
Revised patch below.

josh

From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Sun, 26 Oct 2014 19:19:16 -0400
Subject: [PATCH] move d_rcu from overlapping d_child to overlapping d_alias

commit 946e51f2bf37f1656916eb75bd0742ba33983c28 upstream

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Backported-by: Josh Boyer <jwboyer@xxxxxxxxxxxxxxxxx>
Signed-off-by: Josh Boyer <jwboyer@xxxxxxxxxxxxxxxxx>
---
 arch/powerpc/platforms/cell/spufs/inode.c       |  2 +-
 drivers/staging/lustre/lustre/llite/dcache.c    |  2 +-
 drivers/staging/lustre/lustre/llite/llite_lib.c |  2 +-
 drivers/staging/lustre/lustre/llite/namei.c     |  8 ++--
 fs/affs/amigaffs.c                              |  2 +-
 fs/autofs4/expire.c                             | 12 +++---
 fs/autofs4/root.c                               |  2 +-
 fs/ceph/dir.c                                   |  8 ++--
 fs/ceph/inode.c                                 |  2 +-
 fs/cifs/inode.c                                 |  2 +-
 fs/coda/cache.c                                 |  2 +-
 fs/dcache.c                                     | 52 ++++++++++++-------------
 fs/debugfs/inode.c                              |  2 +-
 fs/exportfs/expfs.c                             |  2 +-
 fs/libfs.c                                      | 12 +++---
 fs/ncpfs/dir.c                                  |  2 +-
 fs/ncpfs/ncplib_kernel.h                        |  4 +-
 fs/nfs/getroot.c                                |  2 +-
 fs/notify/fsnotify.c                            |  4 +-
 fs/ocfs2/dcache.c                               |  2 +-
 include/linux/dcache.h                          |  8 ++--
 kernel/trace/trace.c                            |  4 +-
 kernel/trace/trace_events.c                     |  2 +-
 security/selinux/selinuxfs.c                    |  6 +--
 24 files changed, 73 insertions(+), 73 deletions(-)

diff --git a/arch/powerpc/platforms/cell/spufs/inode.c b/arch/powerpc/platforms/cell/spufs/inode.c
index 87ba7cf99cd7..65d633f20d37 100644
--- a/arch/powerpc/platforms/cell/spufs/inode.c
+++ b/arch/powerpc/platforms/cell/spufs/inode.c
@@ -164,7 +164,7 @@ static void spufs_prune_dir(struct dentry *dir)
 	struct dentry *dentry, *tmp;
 
 	mutex_lock(&dir->d_inode->i_mutex);
-	list_for_each_entry_safe(dentry, tmp, &dir->d_subdirs, d_u.d_child) {
+	list_for_each_entry_safe(dentry, tmp, &dir->d_subdirs, d_child) {
 		spin_lock(&dentry->d_lock);
 		if (!(d_unhashed(dentry)) && dentry->d_inode) {
 			dget_dlock(dentry);
diff --git a/drivers/staging/lustre/lustre/llite/dcache.c b/drivers/staging/lustre/lustre/llite/dcache.c
index 49ae207ad425..e2add5fde0fe 100644
--- a/drivers/staging/lustre/lustre/llite/dcache.c
+++ b/drivers/staging/lustre/lustre/llite/dcache.c
@@ -258,7 +258,7 @@ void ll_invalidate_aliases(struct inode *inode)
 	       inode->i_ino, inode->i_generation, inode);
 
 	ll_lock_dcache(inode);
-	ll_d_hlist_for_each_entry(dentry, p, &inode->i_dentry, d_alias) {
+	ll_d_hlist_for_each_entry(dentry, p, &inode->i_dentry, d_u.d_alias) {
 		CDEBUG(D_DENTRY, "dentry in drop %.*s (%p) parent %p "
 		       "inode %p flags %d\n", dentry->d_name.len,
 		       dentry->d_name.name, dentry, dentry->d_parent,
diff --git a/drivers/staging/lustre/lustre/llite/llite_lib.c b/drivers/staging/lustre/lustre/llite/llite_lib.c
index 0c59e26c0805..36e62524a37b 100644
--- a/drivers/staging/lustre/lustre/llite/llite_lib.c
+++ b/drivers/staging/lustre/lustre/llite/llite_lib.c
@@ -704,7 +704,7 @@ void lustre_dump_dentry(struct dentry *dentry, int recur)
 		return;
 
 	list_for_each(tmp, &dentry->d_subdirs) {
-		struct dentry *d = list_entry(tmp, struct dentry, d_u.d_child);
+		struct dentry *d = list_entry(tmp, struct dentry, d_child);
 		lustre_dump_dentry(d, recur - 1);
 	}
 }
diff --git a/drivers/staging/lustre/lustre/llite/namei.c b/drivers/staging/lustre/lustre/llite/namei.c
index 0dc7173bbd41..9de0d51e33a2 100644
--- a/drivers/staging/lustre/lustre/llite/namei.c
+++ b/drivers/staging/lustre/lustre/llite/namei.c
@@ -167,14 +167,14 @@ static void ll_invalidate_negative_children(struct inode *dir)
 	struct ll_d_hlist_node *p;
 
 	ll_lock_dcache(dir);
-	ll_d_hlist_for_each_entry(dentry, p, &dir->i_dentry, d_alias) {
+	ll_d_hlist_for_each_entry(dentry, p, &dir->i_dentry, d_u.d_alias) {
 		spin_lock(&dentry->d_lock);
 		if (!list_empty(&dentry->d_subdirs)) {
 			struct dentry *child;
 
 			list_for_each_entry_safe(child, tmp_subdir,
 						 &dentry->d_subdirs,
-						 d_u.d_child) {
+						 d_child) {
 				if (child->d_inode == NULL)
 					d_lustre_invalidate(child, 1);
 			}
@@ -362,7 +362,7 @@ static struct dentry *ll_find_alias(struct inode *inode, struct dentry *dentry)
 	discon_alias = invalid_alias = NULL;
 
 	ll_lock_dcache(inode);
-	ll_d_hlist_for_each_entry(alias, p, &inode->i_dentry, d_alias) {
+	ll_d_hlist_for_each_entry(alias, p, &inode->i_dentry, d_u.d_alias) {
 		LASSERT(alias != dentry);
 
 		spin_lock(&alias->d_lock);
@@ -943,7 +943,7 @@ static void ll_get_child_fid(struct inode * dir, struct qstr *name,
 {
 	struct dentry *parent, *child;
 
-	parent = ll_d_hlist_entry(dir->i_dentry, struct dentry, d_alias);
+	parent = ll_d_hlist_entry(dir->i_dentry, struct dentry, d_u.d_alias);
 	child = d_lookup(parent, name);
 	if (child) {
 		if (child->d_inode)
diff --git a/fs/affs/amigaffs.c b/fs/affs/amigaffs.c
index 406b29836b19..a674c114fd8e 100644
--- a/fs/affs/amigaffs.c
+++ b/fs/affs/amigaffs.c
@@ -127,7 +127,7 @@ affs_fix_dcache(struct inode *inode, u32 entry_ino)
 {
 	struct dentry *dentry;
 	spin_lock(&inode->i_lock);
-	hlist_for_each_entry(dentry, &inode->i_dentry, d_alias) {
+	hlist_for_each_entry(dentry, &inode->i_dentry, d_u.d_alias) {
 		if (entry_ino == (u32)(long)dentry->d_fsdata) {
 			dentry->d_fsdata = (void *)inode->i_ino;
 			break;
diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c
index a7be57e39be7..11c6cddff1b9 100644
--- a/fs/autofs4/expire.c
+++ b/fs/autofs4/expire.c
@@ -91,7 +91,7 @@ static struct dentry *get_next_positive_subdir(struct dentry *prev,
 	spin_lock(&root->d_lock);
 
 	if (prev)
-		next = prev->d_u.d_child.next;
+		next = prev->d_child.next;
 	else {
 		prev = dget_dlock(root);
 		next = prev->d_subdirs.next;
@@ -105,13 +105,13 @@ cont:
 		return NULL;
 	}
 
-	q = list_entry(next, struct dentry, d_u.d_child);
+	q = list_entry(next, struct dentry, d_child);
 
 	spin_lock_nested(&q->d_lock, DENTRY_D_LOCK_NESTED);
 	/* Already gone or negative dentry (under construction) - try next */
 	if (!d_count(q) || !simple_positive(q)) {
 		spin_unlock(&q->d_lock);
-		next = q->d_u.d_child.next;
+		next = q->d_child.next;
 		goto cont;
 	}
 	dget_dlock(q);
@@ -161,13 +161,13 @@ again:
 				goto relock;
 			}
 			spin_unlock(&p->d_lock);
-			next = p->d_u.d_child.next;
+			next = p->d_child.next;
 			p = parent;
 			if (next != &parent->d_subdirs)
 				break;
 		}
 	}
-	ret = list_entry(next, struct dentry, d_u.d_child);
+	ret = list_entry(next, struct dentry, d_child);
 
 	spin_lock_nested(&ret->d_lock, DENTRY_D_LOCK_NESTED);
 	/* Negative dentry - try next */
@@ -460,7 +460,7 @@ found:
 	spin_lock(&sbi->lookup_lock);
 	spin_lock(&expired->d_parent->d_lock);
 	spin_lock_nested(&expired->d_lock, DENTRY_D_LOCK_NESTED);
-	list_move(&expired->d_parent->d_subdirs, &expired->d_u.d_child);
+	list_move(&expired->d_parent->d_subdirs, &expired->d_child);
 	spin_unlock(&expired->d_lock);
 	spin_unlock(&expired->d_parent->d_lock);
 	spin_unlock(&sbi->lookup_lock);
diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c
index cdb25ebccc4c..38a9e0fa5177 100644
--- a/fs/autofs4/root.c
+++ b/fs/autofs4/root.c
@@ -659,7 +659,7 @@ static void autofs_clear_leaf_automount_flags(struct dentry *dentry)
 	/* only consider parents below dentrys in the root */
 	if (IS_ROOT(parent->d_parent))
 		return;
-	d_child = &dentry->d_u.d_child;
+	d_child = &dentry->d_child;
 	/* Set parent managed if it's becoming empty */
 	if (d_child->next == &parent->d_subdirs &&
 	    d_child->prev == &parent->d_subdirs)
diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index c29d6ae68874..51ea03313df9 100644
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -111,7 +111,7 @@ static int fpos_cmp(loff_t l, loff_t r)
 /*
  * When possible, we try to satisfy a readdir by peeking at the
  * dcache.  We make this work by carefully ordering dentries on
- * d_u.d_child when we initially get results back from the MDS, and
+ * d_child when we initially get results back from the MDS, and
  * falling back to a "normal" sync readdir if any dentries in the dir
  * are dropped.
  *
@@ -147,11 +147,11 @@ static int __dcache_readdir(struct file *file,  struct dir_context *ctx,
 		p = parent->d_subdirs.prev;
 		dout(" initial p %p/%p\n", p->prev, p->next);
 	} else {
-		p = last->d_u.d_child.prev;
+		p = last->d_child.prev;
 	}
 
 more:
-	dentry = list_entry(p, struct dentry, d_u.d_child);
+	dentry = list_entry(p, struct dentry, d_child);
 	di = ceph_dentry(dentry);
 	while (1) {
 		dout(" p %p/%p %s d_subdirs %p/%p\n", p->prev, p->next,
@@ -174,7 +174,7 @@ more:
 		     !dentry->d_inode ? " null" : "");
 		spin_unlock(&dentry->d_lock);
 		p = p->prev;
-		dentry = list_entry(p, struct dentry, d_u.d_child);
+		dentry = list_entry(p, struct dentry, d_child);
 		di = ceph_dentry(dentry);
 	}
 
diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index 04c89c266cec..c3e103ff18bd 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -1399,7 +1399,7 @@ retry_lookup:
 			/* reorder parent's d_subdirs */
 			spin_lock(&parent->d_lock);
 			spin_lock_nested(&dn->d_lock, DENTRY_D_LOCK_NESTED);
-			list_move(&dn->d_u.d_child, &parent->d_subdirs);
+			list_move(&dn->d_child, &parent->d_subdirs);
 			spin_unlock(&dn->d_lock);
 			spin_unlock(&parent->d_lock);
 		}
diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
index 7899a40465b3..6d1dd0942937 100644
--- a/fs/cifs/inode.c
+++ b/fs/cifs/inode.c
@@ -887,7 +887,7 @@ inode_has_hashed_dentries(struct inode *inode)
 	struct dentry *dentry;
 
 	spin_lock(&inode->i_lock);
-	hlist_for_each_entry(dentry, &inode->i_dentry, d_alias) {
+	hlist_for_each_entry(dentry, &inode->i_dentry, d_u.d_alias) {
 		if (!d_unhashed(dentry) || IS_ROOT(dentry)) {
 			spin_unlock(&inode->i_lock);
 			return true;
diff --git a/fs/coda/cache.c b/fs/coda/cache.c
index 278f8fdeb9ef..46ee6f238985 100644
--- a/fs/coda/cache.c
+++ b/fs/coda/cache.c
@@ -92,7 +92,7 @@ static void coda_flag_children(struct dentry *parent, int flag)
 	struct dentry *de;
 
 	spin_lock(&parent->d_lock);
-	list_for_each_entry(de, &parent->d_subdirs, d_u.d_child) {
+	list_for_each_entry(de, &parent->d_subdirs, d_child) {
 		/* don't know what to do with negative dentries */
 		if (de->d_inode ) 
 			coda_flag_inode(de->d_inode, flag);
diff --git a/fs/dcache.c b/fs/dcache.c
index 34b40be8af11..8d7c2b34cb3f 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -44,7 +44,7 @@
 /*
  * Usage:
  * dcache->d_inode->i_lock protects:
- *   - i_dentry, d_alias, d_inode of aliases
+ *   - i_dentry, d_u.d_alias, d_inode of aliases
  * dcache_hash_bucket lock protects:
  *   - the dcache hash table
  * s_anon bl list spinlock protects:
@@ -59,7 +59,7 @@
  *   - d_unhashed()
  *   - d_parent and d_subdirs
  *   - childrens' d_child and d_parent
- *   - d_alias, d_inode
+ *   - d_u.d_alias, d_inode
  *
  * Ordering:
  * dentry->d_inode->i_lock
@@ -239,7 +239,6 @@ static void __d_free(struct rcu_head *head)
 {
 	struct dentry *dentry = container_of(head, struct dentry, d_u.d_rcu);
 
-	WARN_ON(!hlist_unhashed(&dentry->d_alias));
 	if (dname_external(dentry))
 		kfree(dentry->d_name.name);
 	kmem_cache_free(dentry_cache, dentry); 
@@ -247,6 +246,7 @@ static void __d_free(struct rcu_head *head)
 
 static void dentry_free(struct dentry *dentry)
 {
+	WARN_ON(!hlist_unhashed(&dentry->d_u.d_alias));
 	/* if dentry was never visible to RCU, immediate free is OK */
 	if (!(dentry->d_flags & DCACHE_RCUACCESS))
 		__d_free(&dentry->d_u.d_rcu);
@@ -280,7 +280,7 @@ static void dentry_iput(struct dentry * dentry)
 	struct inode *inode = dentry->d_inode;
 	if (inode) {
 		dentry->d_inode = NULL;
-		hlist_del_init(&dentry->d_alias);
+		hlist_del_init(&dentry->d_u.d_alias);
 		spin_unlock(&dentry->d_lock);
 		spin_unlock(&inode->i_lock);
 		if (!inode->i_nlink)
@@ -305,7 +305,7 @@ static void dentry_unlink_inode(struct dentry * dentry)
 	struct inode *inode = dentry->d_inode;
 	__d_clear_type(dentry);
 	dentry->d_inode = NULL;
-	hlist_del_init(&dentry->d_alias);
+	hlist_del_init(&dentry->d_u.d_alias);
 	dentry_rcuwalk_barrier(dentry);
 	spin_unlock(&dentry->d_lock);
 	spin_unlock(&inode->i_lock);
@@ -465,7 +465,7 @@ static void __dentry_kill(struct dentry *dentry)
 	}
 	/* if it was on the hash then remove it */
 	__d_drop(dentry);
-	list_del(&dentry->d_u.d_child);
+	list_del(&dentry->d_child);
 	/*
 	 * Inform d_walk() that we are no longer attached to the
 	 * dentry tree
@@ -746,7 +746,7 @@ static struct dentry *__d_find_alias(struct inode *inode)
 
 again:
 	discon_alias = NULL;
-	hlist_for_each_entry(alias, &inode->i_dentry, d_alias) {
+	hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) {
 		spin_lock(&alias->d_lock);
  		if (S_ISDIR(inode->i_mode) || !d_unhashed(alias)) {
 			if (IS_ROOT(alias) &&
@@ -796,7 +796,7 @@ void d_prune_aliases(struct inode *inode)
 	struct dentry *dentry;
 restart:
 	spin_lock(&inode->i_lock);
-	hlist_for_each_entry(dentry, &inode->i_dentry, d_alias) {
+	hlist_for_each_entry(dentry, &inode->i_dentry, d_u.d_alias) {
 		spin_lock(&dentry->d_lock);
 		if (!dentry->d_lockref.count) {
 			/*
@@ -1081,7 +1081,7 @@ repeat:
 resume:
 	while (next != &this_parent->d_subdirs) {
 		struct list_head *tmp = next;
-		struct dentry *dentry = list_entry(tmp, struct dentry, d_u.d_child);
+		struct dentry *dentry = list_entry(tmp, struct dentry, d_child);
 		next = tmp->next;
 
 		spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
@@ -1133,7 +1133,7 @@ resume:
 			goto rename_retry;
 		}
 		rcu_read_unlock();
-		next = child->d_u.d_child.next;
+		next = child->d_child.next;
 		goto resume;
 	}
 	if (need_seqretry(&rename_lock, seq)) {
@@ -1468,8 +1468,8 @@ struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name)
 	INIT_HLIST_BL_NODE(&dentry->d_hash);
 	INIT_LIST_HEAD(&dentry->d_lru);
 	INIT_LIST_HEAD(&dentry->d_subdirs);
-	INIT_HLIST_NODE(&dentry->d_alias);
-	INIT_LIST_HEAD(&dentry->d_u.d_child);
+	INIT_HLIST_NODE(&dentry->d_u.d_alias);
+	INIT_LIST_HEAD(&dentry->d_child);
 	d_set_d_op(dentry, dentry->d_sb->s_d_op);
 
 	this_cpu_inc(nr_dentry);
@@ -1499,7 +1499,7 @@ struct dentry *d_alloc(struct dentry * parent, const struct qstr *name)
 	 */
 	__dget_dlock(parent);
 	dentry->d_parent = parent;
-	list_add(&dentry->d_u.d_child, &parent->d_subdirs);
+	list_add(&dentry->d_child, &parent->d_subdirs);
 	spin_unlock(&parent->d_lock);
 
 	return dentry;
@@ -1592,7 +1592,7 @@ static void __d_instantiate(struct dentry *dentry, struct inode *inode)
 	spin_lock(&dentry->d_lock);
 	__d_set_type(dentry, add_flags);
 	if (inode)
-		hlist_add_head(&dentry->d_alias, &inode->i_dentry);
+		hlist_add_head(&dentry->d_u.d_alias, &inode->i_dentry);
 	dentry->d_inode = inode;
 	dentry_rcuwalk_barrier(dentry);
 	spin_unlock(&dentry->d_lock);
@@ -1616,7 +1616,7 @@ static void __d_instantiate(struct dentry *dentry, struct inode *inode)
  
 void d_instantiate(struct dentry *entry, struct inode * inode)
 {
-	BUG_ON(!hlist_unhashed(&entry->d_alias));
+	BUG_ON(!hlist_unhashed(&entry->d_u.d_alias));
 	if (inode)
 		spin_lock(&inode->i_lock);
 	__d_instantiate(entry, inode);
@@ -1655,7 +1655,7 @@ static struct dentry *__d_instantiate_unique(struct dentry *entry,
 		return NULL;
 	}
 
-	hlist_for_each_entry(alias, &inode->i_dentry, d_alias) {
+	hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) {
 		/*
 		 * Don't need alias->d_lock here, because aliases with
 		 * d_parent == entry->d_parent are not subject to name or
@@ -1681,7 +1681,7 @@ struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode)
 {
 	struct dentry *result;
 
-	BUG_ON(!hlist_unhashed(&entry->d_alias));
+	BUG_ON(!hlist_unhashed(&entry->d_u.d_alias));
 
 	if (inode)
 		spin_lock(&inode->i_lock);
@@ -1712,7 +1712,7 @@ EXPORT_SYMBOL(d_instantiate_unique);
  */
 int d_instantiate_no_diralias(struct dentry *entry, struct inode *inode)
 {
-	BUG_ON(!hlist_unhashed(&entry->d_alias));
+	BUG_ON(!hlist_unhashed(&entry->d_u.d_alias));
 
 	spin_lock(&inode->i_lock);
 	if (S_ISDIR(inode->i_mode) && !hlist_empty(&inode->i_dentry)) {
@@ -1751,7 +1751,7 @@ static struct dentry * __d_find_any_alias(struct inode *inode)
 
 	if (hlist_empty(&inode->i_dentry))
 		return NULL;
-	alias = hlist_entry(inode->i_dentry.first, struct dentry, d_alias);
+	alias = hlist_entry(inode->i_dentry.first, struct dentry, d_u.d_alias);
 	__dget(alias);
 	return alias;
 }
@@ -1813,7 +1813,7 @@ static struct dentry *__d_obtain_alias(struct inode *inode, int disconnected)
 	spin_lock(&tmp->d_lock);
 	tmp->d_inode = inode;
 	tmp->d_flags |= add_flags;
-	hlist_add_head(&tmp->d_alias, &inode->i_dentry);
+	hlist_add_head(&tmp->d_u.d_alias, &inode->i_dentry);
 	hlist_bl_lock(&tmp->d_sb->s_anon);
 	hlist_bl_add_head(&tmp->d_hash, &tmp->d_sb->s_anon);
 	hlist_bl_unlock(&tmp->d_sb->s_anon);
@@ -2248,7 +2248,7 @@ int d_validate(struct dentry *dentry, struct dentry *dparent)
 	struct dentry *child;
 
 	spin_lock(&dparent->d_lock);
-	list_for_each_entry(child, &dparent->d_subdirs, d_u.d_child) {
+	list_for_each_entry(child, &dparent->d_subdirs, d_child) {
 		if (dentry == child) {
 			spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
 			__dget_dlock(dentry);
@@ -2525,13 +2525,13 @@ static void __d_move(struct dentry *dentry, struct dentry *target,
 		/* splicing a tree */
 		dentry->d_parent = target->d_parent;
 		target->d_parent = target;
-		list_del_init(&target->d_u.d_child);
-		list_move(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs);
+		list_del_init(&target->d_child);
+		list_move(&dentry->d_child, &dentry->d_parent->d_subdirs);
 	} else {
 		/* swapping two dentries */
 		swap(dentry->d_parent, target->d_parent);
-		list_move(&target->d_u.d_child, &target->d_parent->d_subdirs);
-		list_move(&dentry->d_u.d_child, &dentry->d_parent->d_subdirs);
+		list_move(&target->d_child, &target->d_parent->d_subdirs);
+		list_move(&dentry->d_child, &dentry->d_parent->d_subdirs);
 		if (exchange)
 			fsnotify_d_move(target);
 		fsnotify_d_move(dentry);
@@ -3322,7 +3322,7 @@ void d_tmpfile(struct dentry *dentry, struct inode *inode)
 {
 	inode_dec_link_count(inode);
 	BUG_ON(dentry->d_name.name != dentry->d_iname ||
-		!hlist_unhashed(&dentry->d_alias) ||
+		!hlist_unhashed(&dentry->d_u.d_alias) ||
 		!d_unlinked(dentry));
 	spin_lock(&dentry->d_parent->d_lock);
 	spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index 1e3b99d3db0d..05f2960ed7c3 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -553,7 +553,7 @@ void debugfs_remove_recursive(struct dentry *dentry)
 	 * use the d_u.d_child as the rcu head and corrupt this list.
 	 */
 	spin_lock(&parent->d_lock);
-	list_for_each_entry(child, &parent->d_subdirs, d_u.d_child) {
+	list_for_each_entry(child, &parent->d_subdirs, d_child) {
 		if (!debugfs_positive(child))
 			continue;
 
diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c
index b01fbfb51f43..a3aa6baad1a1 100644
--- a/fs/exportfs/expfs.c
+++ b/fs/exportfs/expfs.c
@@ -50,7 +50,7 @@ find_acceptable_alias(struct dentry *result,
 
 	inode = result->d_inode;
 	spin_lock(&inode->i_lock);
-	hlist_for_each_entry(dentry, &inode->i_dentry, d_alias) {
+	hlist_for_each_entry(dentry, &inode->i_dentry, d_u.d_alias) {
 		dget(dentry);
 		spin_unlock(&inode->i_lock);
 		if (toput)
diff --git a/fs/libfs.c b/fs/libfs.c
index 88e3e00e2eca..e801b983b46b 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -114,18 +114,18 @@ loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence)
 
 			spin_lock(&dentry->d_lock);
 			/* d_lock not required for cursor */
-			list_del(&cursor->d_u.d_child);
+			list_del(&cursor->d_child);
 			p = dentry->d_subdirs.next;
 			while (n && p != &dentry->d_subdirs) {
 				struct dentry *next;
-				next = list_entry(p, struct dentry, d_u.d_child);
+				next = list_entry(p, struct dentry, d_child);
 				spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED);
 				if (simple_positive(next))
 					n--;
 				spin_unlock(&next->d_lock);
 				p = p->next;
 			}
-			list_add_tail(&cursor->d_u.d_child, p);
+			list_add_tail(&cursor->d_child, p);
 			spin_unlock(&dentry->d_lock);
 		}
 	}
@@ -150,7 +150,7 @@ int dcache_readdir(struct file *file, struct dir_context *ctx)
 {
 	struct dentry *dentry = file->f_path.dentry;
 	struct dentry *cursor = file->private_data;
-	struct list_head *p, *q = &cursor->d_u.d_child;
+	struct list_head *p, *q = &cursor->d_child;
 
 	if (!dir_emit_dots(file, ctx))
 		return 0;
@@ -159,7 +159,7 @@ int dcache_readdir(struct file *file, struct dir_context *ctx)
 		list_move(q, &dentry->d_subdirs);
 
 	for (p = q->next; p != &dentry->d_subdirs; p = p->next) {
-		struct dentry *next = list_entry(p, struct dentry, d_u.d_child);
+		struct dentry *next = list_entry(p, struct dentry, d_child);
 		spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED);
 		if (!simple_positive(next)) {
 			spin_unlock(&next->d_lock);
@@ -287,7 +287,7 @@ int simple_empty(struct dentry *dentry)
 	int ret = 0;
 
 	spin_lock(&dentry->d_lock);
-	list_for_each_entry(child, &dentry->d_subdirs, d_u.d_child) {
+	list_for_each_entry(child, &dentry->d_subdirs, d_child) {
 		spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
 		if (simple_positive(child)) {
 			spin_unlock(&child->d_lock);
diff --git a/fs/ncpfs/dir.c b/fs/ncpfs/dir.c
index 08b8ea8c353e..3a8ed0fb07be 100644
--- a/fs/ncpfs/dir.c
+++ b/fs/ncpfs/dir.c
@@ -406,7 +406,7 @@ ncp_dget_fpos(struct dentry *dentry, struct dentry *parent, unsigned long fpos)
 	spin_lock(&parent->d_lock);
 	next = parent->d_subdirs.next;
 	while (next != &parent->d_subdirs) {
-		dent = list_entry(next, struct dentry, d_u.d_child);
+		dent = list_entry(next, struct dentry, d_child);
 		if ((unsigned long)dent->d_fsdata == fpos) {
 			if (dent->d_inode)
 				dget(dent);
diff --git a/fs/ncpfs/ncplib_kernel.h b/fs/ncpfs/ncplib_kernel.h
index 32c06587351a..6d5e7c56c79d 100644
--- a/fs/ncpfs/ncplib_kernel.h
+++ b/fs/ncpfs/ncplib_kernel.h
@@ -194,7 +194,7 @@ ncp_renew_dentries(struct dentry *parent)
 	spin_lock(&parent->d_lock);
 	next = parent->d_subdirs.next;
 	while (next != &parent->d_subdirs) {
-		dentry = list_entry(next, struct dentry, d_u.d_child);
+		dentry = list_entry(next, struct dentry, d_child);
 
 		if (dentry->d_fsdata == NULL)
 			ncp_age_dentry(server, dentry);
@@ -216,7 +216,7 @@ ncp_invalidate_dircache_entries(struct dentry *parent)
 	spin_lock(&parent->d_lock);
 	next = parent->d_subdirs.next;
 	while (next != &parent->d_subdirs) {
-		dentry = list_entry(next, struct dentry, d_u.d_child);
+		dentry = list_entry(next, struct dentry, d_child);
 		dentry->d_fsdata = NULL;
 		ncp_age_dentry(server, dentry);
 		next = next->next;
diff --git a/fs/nfs/getroot.c b/fs/nfs/getroot.c
index 880618a8b048..ebc6a0add5ae 100644
--- a/fs/nfs/getroot.c
+++ b/fs/nfs/getroot.c
@@ -58,7 +58,7 @@ static int nfs_superblock_set_dummy_root(struct super_block *sb, struct inode *i
 		 */
 		spin_lock(&sb->s_root->d_inode->i_lock);
 		spin_lock(&sb->s_root->d_lock);
-		hlist_del_init(&sb->s_root->d_alias);
+		hlist_del_init(&sb->s_root->d_u.d_alias);
 		spin_unlock(&sb->s_root->d_lock);
 		spin_unlock(&sb->s_root->d_inode->i_lock);
 	}
diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
index 9d3e9c50066a..700129940c6e 100644
--- a/fs/notify/fsnotify.c
+++ b/fs/notify/fsnotify.c
@@ -63,14 +63,14 @@ void __fsnotify_update_child_dentry_flags(struct inode *inode)
 	spin_lock(&inode->i_lock);
 	/* run all of the dentries associated with this inode.  Since this is a
 	 * directory, there damn well better only be one item on this list */
-	hlist_for_each_entry(alias, &inode->i_dentry, d_alias) {
+	hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) {
 		struct dentry *child;
 
 		/* run all of the children of the original inode and fix their
 		 * d_flags to indicate parental interest (their parent is the
 		 * original inode) */
 		spin_lock(&alias->d_lock);
-		list_for_each_entry(child, &alias->d_subdirs, d_u.d_child) {
+		list_for_each_entry(child, &alias->d_subdirs, d_child) {
 			if (!child->d_inode)
 				continue;
 
diff --git a/fs/ocfs2/dcache.c b/fs/ocfs2/dcache.c
index e2e05a106beb..92edcfc23c1c 100644
--- a/fs/ocfs2/dcache.c
+++ b/fs/ocfs2/dcache.c
@@ -172,7 +172,7 @@ struct dentry *ocfs2_find_local_alias(struct inode *inode,
 	struct dentry *dentry;
 
 	spin_lock(&inode->i_lock);
-	hlist_for_each_entry(dentry, &inode->i_dentry, d_alias) {
+	hlist_for_each_entry(dentry, &inode->i_dentry, d_u.d_alias) {
 		spin_lock(&dentry->d_lock);
 		if (ocfs2_match_dentry(dentry, parent_blkno, skip_unhashed)) {
 			trace_ocfs2_find_local_alias(dentry->d_name.len,
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 75a227cc7ce2..82b5d1c2b856 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -125,15 +125,15 @@ struct dentry {
 	void *d_fsdata;			/* fs-specific data */
 
 	struct list_head d_lru;		/* LRU list */
+	struct list_head d_child;	/* child of parent list */
+	struct list_head d_subdirs;	/* our children */
 	/*
-	 * d_child and d_rcu can share memory
+	 * d_alias and d_rcu can share memory
 	 */
 	union {
-		struct list_head d_child;	/* child of parent list */
+		struct hlist_node d_alias;	/* inode alias list */
 	 	struct rcu_head d_rcu;
 	} d_u;
-	struct list_head d_subdirs;	/* our children */
-	struct hlist_node d_alias;	/* inode alias list */
 };
 
 /*
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 15209335888d..09acba6e908a 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -6411,7 +6411,7 @@ static int instance_mkdir (struct inode *inode, struct dentry *dentry, umode_t m
 	int ret;
 
 	/* Paranoid: Make sure the parent is the "instances" directory */
-	parent = hlist_entry(inode->i_dentry.first, struct dentry, d_alias);
+	parent = hlist_entry(inode->i_dentry.first, struct dentry, d_u.d_alias);
 	if (WARN_ON_ONCE(parent != trace_instance_dir))
 		return -ENOENT;
 
@@ -6438,7 +6438,7 @@ static int instance_rmdir(struct inode *inode, struct dentry *dentry)
 	int ret;
 
 	/* Paranoid: Make sure the parent is the "instances" directory */
-	parent = hlist_entry(inode->i_dentry.first, struct dentry, d_alias);
+	parent = hlist_entry(inode->i_dentry.first, struct dentry, d_u.d_alias);
 	if (WARN_ON_ONCE(parent != trace_instance_dir))
 		return -ENOENT;
 
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index ef06ce7e9cf8..85f9d33b4ad8 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -461,7 +461,7 @@ static void remove_event_file_dir(struct ftrace_event_file *file)
 
 	if (dir) {
 		spin_lock(&dir->d_lock);	/* probably unneeded */
-		list_for_each_entry(child, &dir->d_subdirs, d_u.d_child) {
+		list_for_each_entry(child, &dir->d_subdirs, d_child) {
 			if (child->d_inode)	/* probably unneeded */
 				child->d_inode->i_private = NULL;
 		}
diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c
index c71737f6d1cc..33db1ad4fd10 100644
--- a/security/selinux/selinuxfs.c
+++ b/security/selinux/selinuxfs.c
@@ -1200,7 +1200,7 @@ static void sel_remove_entries(struct dentry *de)
 	spin_lock(&de->d_lock);
 	node = de->d_subdirs.next;
 	while (node != &de->d_subdirs) {
-		struct dentry *d = list_entry(node, struct dentry, d_u.d_child);
+		struct dentry *d = list_entry(node, struct dentry, d_child);
 
 		spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED);
 		list_del_init(node);
@@ -1674,12 +1674,12 @@ static void sel_remove_classes(void)
 
 	list_for_each(class_node, &class_dir->d_subdirs) {
 		struct dentry *class_subdir = list_entry(class_node,
-					struct dentry, d_u.d_child);
+					struct dentry, d_child);
 		struct list_head *class_subdir_node;
 
 		list_for_each(class_subdir_node, &class_subdir->d_subdirs) {
 			struct dentry *d = list_entry(class_subdir_node,
-						struct dentry, d_u.d_child);
+						struct dentry, d_child);
 
 			if (d->d_inode)
 				if (d->d_inode->i_mode & S_IFDIR)
-- 
2.1.0

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