From 4051a9115ad24bb9a691774730ca9c1dd56de665 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Wed, 17 Sep 2025 22:19:10 -0400
Subject: new helper: simple_remove_by_name()

simple_recursive_removal(), but instead of victim dentry it takes
parent + name.

Used to be open-coded in fs/fuse/control.c, but there's no need to expose
the guts of that thing there and there are other potential users, so
let's lift it into libfs...

Acked-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 include/linux/fs.h | 2 ++
 1 file changed, 2 insertions(+)

(limited to 'include/linux')

diff --git a/include/linux/fs.h b/include/linux/fs.h
index c895146c1444..28bd4e8d3892 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3631,6 +3631,8 @@ extern int simple_rename(struct mnt_idmap *, struct inode *,
 			 unsigned int);
 extern void simple_recursive_removal(struct dentry *,
                               void (*callback)(struct dentry *));
+extern void simple_remove_by_name(struct dentry *, const char *,
+                              void (*callback)(struct dentry *));
 extern void locked_recursive_removal(struct dentry *,
                               void (*callback)(struct dentry *));
 extern int noop_fsync(struct file *, loff_t, loff_t, int);
-- 
cgit v1.2.3


From 1552ddc7fade1ae55af298580ef6c913b8db74bc Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Fri, 19 Sep 2025 17:46:01 -0400
Subject: new helper: simple_done_creating()

should be paired with simple_start_creating() - unlocks parent and
drops dentry reference.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 fs/libfs.c         | 8 ++++++++
 include/linux/fs.h | 1 +
 2 files changed, 9 insertions(+)

(limited to 'include/linux')

diff --git a/fs/libfs.c b/fs/libfs.c
index d029aff41f66..a033f35493d0 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -2326,3 +2326,11 @@ struct dentry *simple_start_creating(struct dentry *parent, const char *name)
 	return dentry;
 }
 EXPORT_SYMBOL(simple_start_creating);
+
+/* parent must have been held exclusive since simple_start_creating() */
+void simple_done_creating(struct dentry *child)
+{
+	inode_unlock(child->d_parent->d_inode);
+	dput(child);
+}
+EXPORT_SYMBOL(simple_done_creating);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 28bd4e8d3892..f5037c556f61 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3662,6 +3662,7 @@ extern int simple_fill_super(struct super_block *, unsigned long,
 extern int simple_pin_fs(struct file_system_type *, struct vfsmount **mount, int *count);
 extern void simple_release_fs(struct vfsmount **mount, int *count);
 struct dentry *simple_start_creating(struct dentry *, const char *);
+void simple_done_creating(struct dentry *);
 
 extern ssize_t simple_read_from_buffer(void __user *to, size_t count,
 			loff_t *ppos, const void *from, size_t available);
-- 
cgit v1.2.3


From 8a210cacf5dc2a6210ee42aeca5cd03b2400876f Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Mon, 3 Mar 2025 19:15:35 -0500
Subject: introduce a flag for explicitly marking persistently pinned dentries

Some filesystems use a kinda-sorta controlled dentry refcount leak to pin
dentries of created objects in dcache (and undo it when removing those).
Reference is grabbed and not released, but it's not actually _stored_
anywhere.  That works, but it's hard to follow and verify; among other
things, we have no way to tell _which_ of the increments is intended
to be an unpaired one.  Worse, on removal we need to decide whether
the reference had already been dropped, which can be non-trivial if
that removal is on umount and we need to figure out if this dentry is
pinned due to e.g. unlink() not done.  Usually that is handled by using
kill_litter_super() as ->kill_sb(), but there are open-coded special
cases of the same (consider e.g. /proc/self).

Things get simpler if we introduce a new dentry flag (DCACHE_PERSISTENT)
marking those "leaked" dentries.  Having it set claims responsibility
for +1 in refcount.

The end result this series is aiming for:

* get these unbalanced dget() and dput() replaced with new primitives that
  would, in addition to adjusting refcount, set and clear persistency flag.
* instead of having kill_litter_super() mess with removing the remaining
  "leaked" references (e.g. for all tmpfs files that hadn't been removed
  prior to umount), have the regular shrink_dcache_for_umount() strip
  DCACHE_PERSISTENT of all dentries, dropping the corresponding
  reference if it had been set.  After that kill_litter_super() becomes
  an equivalent of kill_anon_super().

Doing that in a single step is not feasible - it would affect too many places
in too many filesystems.  It has to be split into a series.

Here we
	* introduce the new flag
	* teach shrink_dcache_for_umount() to handle it (i.e. remove
and drop refcount on anything that survives to umount with that flag
still set)
	* teach kill_litter_super() that anything with that flag does
*not* need to be unpinned.

Next commits will add primitives for maintaing that flag and convert the
common helpers to those.  After that - a long series of per-filesystem
patches converting to those primitives.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 fs/dcache.c            | 27 ++++++++++++++++++++++-----
 include/linux/dcache.h |  1 +
 2 files changed, 23 insertions(+), 5 deletions(-)

(limited to 'include/linux')

diff --git a/fs/dcache.c b/fs/dcache.c
index 035cccbc9276..f2c9f4fef2a2 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1511,6 +1511,15 @@ out:
 	return ret;
 }
 
+static enum d_walk_ret select_collect_umount(void *_data, struct dentry *dentry)
+{
+	if (dentry->d_flags & DCACHE_PERSISTENT) {
+		dentry->d_flags &= ~DCACHE_PERSISTENT;
+		dentry->d_lockref.count--;
+	}
+	return select_collect(_data, dentry);
+}
+
 static enum d_walk_ret select_collect2(void *_data, struct dentry *dentry)
 {
 	struct select_data *data = _data;
@@ -1539,18 +1548,20 @@ out:
 }
 
 /**
- * shrink_dcache_parent - prune dcache
+ * shrink_dcache_tree - prune dcache
  * @parent: parent of entries to prune
+ * @for_umount: true if we want to unpin the persistent ones
  *
  * Prune the dcache to remove unused children of the parent dentry.
  */
-void shrink_dcache_parent(struct dentry *parent)
+static void shrink_dcache_tree(struct dentry *parent, bool for_umount)
 {
 	for (;;) {
 		struct select_data data = {.start = parent};
 
 		INIT_LIST_HEAD(&data.dispose);
-		d_walk(parent, &data, select_collect);
+		d_walk(parent, &data,
+			for_umount ? select_collect_umount : select_collect);
 
 		if (!list_empty(&data.dispose)) {
 			shrink_dentry_list(&data.dispose);
@@ -1575,6 +1586,11 @@ void shrink_dcache_parent(struct dentry *parent)
 			shrink_dentry_list(&data.dispose);
 	}
 }
+
+void shrink_dcache_parent(struct dentry *parent)
+{
+	shrink_dcache_tree(parent, false);
+}
 EXPORT_SYMBOL(shrink_dcache_parent);
 
 static enum d_walk_ret umount_check(void *_data, struct dentry *dentry)
@@ -1601,7 +1617,7 @@ static enum d_walk_ret umount_check(void *_data, struct dentry *dentry)
 
 static void do_one_tree(struct dentry *dentry)
 {
-	shrink_dcache_parent(dentry);
+	shrink_dcache_tree(dentry, true);
 	d_walk(dentry, dentry, umount_check);
 	d_drop(dentry);
 	dput(dentry);
@@ -3111,7 +3127,8 @@ static enum d_walk_ret d_genocide_kill(void *data, struct dentry *dentry)
 {
 	struct dentry *root = data;
 	if (dentry != root) {
-		if (d_unhashed(dentry) || !dentry->d_inode)
+		if (d_unhashed(dentry) || !dentry->d_inode ||
+		    dentry->d_flags & DCACHE_PERSISTENT)
 			return D_WALK_SKIP;
 
 		if (!(dentry->d_flags & DCACHE_GENOCIDE)) {
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index c83e02b94389..94b58655322a 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -225,6 +225,7 @@ enum dentry_flags {
 	DCACHE_PAR_LOOKUP		= BIT(24),	/* being looked up (with parent locked shared) */
 	DCACHE_DENTRY_CURSOR		= BIT(25),
 	DCACHE_NORCU			= BIT(26),	/* No RCU delay for freeing */
+	DCACHE_PERSISTENT		= BIT(27)
 };
 
 #define DCACHE_MANAGED_DENTRY \
-- 
cgit v1.2.3


From bacdf1d70bbe2027619c7bbbe48b379a806a9678 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Mon, 3 Mar 2025 19:38:04 -0500
Subject: primitives for maintaining persisitency

* d_make_persistent(dentry, inode) - bump refcount, mark persistent and
make hashed positive.  Return value is a borrowed reference to dentry;
it can be used until something removes persistency (at the very least,
until the parent gets unlocked, but some filesystems may have stronger
exclusion).

* d_make_discardable() - remove persistency mark and drop reference.

d_make_persistent() is similar to combination of d_instantiate(), dget()
and setting flag.  The only difference is that unlike d_instantiate()
it accepts hashed and unhashed negatives alike.  It is always called in
strong locking environment (parent held exclusive, or, in some cases,
dentry coming from d_alloc_name()); if we ever start using it with parent
held only shared and dentry coming from d_alloc_parallel(), we'll need
to copy the in-lookup logics from __d_add().

d_make_discardable() is eqiuvalent to combination of removing flag and
dput(); since flag removal requires ->d_lock, there's no point trying
to avoid taking that for refcount decrement as fast_dput() does.
The slow path of dput() has been taken into a helper and reused in
d_make_discardable() instead.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 fs/dcache.c            | 74 ++++++++++++++++++++++++++++++++++++++++----------
 include/linux/dcache.h |  2 ++
 2 files changed, 61 insertions(+), 15 deletions(-)

(limited to 'include/linux')

diff --git a/fs/dcache.c b/fs/dcache.c
index f2c9f4fef2a2..3cc6c3876177 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -869,6 +869,24 @@ locked:
 	return false;
 }
 
+static void finish_dput(struct dentry *dentry)
+	__releases(dentry->d_lock)
+	__releases(RCU)
+{
+	while (lock_for_kill(dentry)) {
+		rcu_read_unlock();
+		dentry = __dentry_kill(dentry);
+		if (!dentry)
+			return;
+		if (retain_dentry(dentry, true)) {
+			spin_unlock(&dentry->d_lock);
+			return;
+		}
+		rcu_read_lock();
+	}
+	rcu_read_unlock();
+	spin_unlock(&dentry->d_lock);
+}
 
 /* 
  * This is dput
@@ -906,22 +924,28 @@ void dput(struct dentry *dentry)
 		rcu_read_unlock();
 		return;
 	}
-	while (lock_for_kill(dentry)) {
-		rcu_read_unlock();
-		dentry = __dentry_kill(dentry);
-		if (!dentry)
-			return;
-		if (retain_dentry(dentry, true)) {
-			spin_unlock(&dentry->d_lock);
-			return;
-		}
-		rcu_read_lock();
-	}
-	rcu_read_unlock();
-	spin_unlock(&dentry->d_lock);
+	finish_dput(dentry);
 }
 EXPORT_SYMBOL(dput);
 
+void d_make_discardable(struct dentry *dentry)
+{
+	spin_lock(&dentry->d_lock);
+	/*
+	 * By the end of the series we'll add
+	 * WARN_ON(!(dentry->d_flags & DCACHE_PERSISTENT);
+	 * here, but while object removal is done by a few common helpers,
+	 * object creation tends to be open-coded (if nothing else, new inode
+	 * needs to be set up), so adding a warning from the very beginning
+	 * would make for much messier patch series.
+	 */
+	dentry->d_flags &= ~DCACHE_PERSISTENT;
+	dentry->d_lockref.count--;
+	rcu_read_lock();
+	finish_dput(dentry);
+}
+EXPORT_SYMBOL(d_make_discardable);
+
 static void to_shrink_list(struct dentry *dentry, struct list_head *list)
 __must_hold(&dentry->d_lock)
 {
@@ -1939,7 +1963,6 @@ static void __d_instantiate(struct dentry *dentry, struct inode *inode)
 	unsigned add_flags = d_flags_for_inode(inode);
 	WARN_ON(d_in_lookup(dentry));
 
-	spin_lock(&dentry->d_lock);
 	/*
 	 * The negative counter only tracks dentries on the LRU. Don't dec if
 	 * d_lru is on another list.
@@ -1952,7 +1975,6 @@ static void __d_instantiate(struct dentry *dentry, struct inode *inode)
 	__d_set_inode_and_type(dentry, inode, add_flags);
 	raw_write_seqcount_end(&dentry->d_seq);
 	fsnotify_update_flags(dentry);
-	spin_unlock(&dentry->d_lock);
 }
 
 /**
@@ -1976,7 +1998,9 @@ void d_instantiate(struct dentry *entry, struct inode * inode)
 	if (inode) {
 		security_d_instantiate(entry, inode);
 		spin_lock(&inode->i_lock);
+		spin_lock(&entry->d_lock);
 		__d_instantiate(entry, inode);
+		spin_unlock(&entry->d_lock);
 		spin_unlock(&inode->i_lock);
 	}
 }
@@ -1995,7 +2019,9 @@ void d_instantiate_new(struct dentry *entry, struct inode *inode)
 	lockdep_annotate_inode_mutex_key(inode);
 	security_d_instantiate(entry, inode);
 	spin_lock(&inode->i_lock);
+	spin_lock(&entry->d_lock);
 	__d_instantiate(entry, inode);
+	spin_unlock(&entry->d_lock);
 	WARN_ON(!(inode->i_state & I_NEW));
 	inode->i_state &= ~I_NEW & ~I_CREATING;
 	/*
@@ -2754,6 +2780,24 @@ void d_add(struct dentry *entry, struct inode *inode)
 }
 EXPORT_SYMBOL(d_add);
 
+struct dentry *d_make_persistent(struct dentry *dentry, struct inode *inode)
+{
+	WARN_ON(!hlist_unhashed(&dentry->d_u.d_alias));
+	WARN_ON(!inode);
+	security_d_instantiate(dentry, inode);
+	spin_lock(&inode->i_lock);
+	spin_lock(&dentry->d_lock);
+	__d_instantiate(dentry, inode);
+	dentry->d_flags |= DCACHE_PERSISTENT;
+	dget_dlock(dentry);
+	if (d_unhashed(dentry))
+		__d_rehash(dentry);
+	spin_unlock(&dentry->d_lock);
+	spin_unlock(&inode->i_lock);
+	return dentry;
+}
+EXPORT_SYMBOL(d_make_persistent);
+
 static void swap_names(struct dentry *dentry, struct dentry *target)
 {
 	if (unlikely(dname_external(target))) {
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 94b58655322a..6ec4066825e3 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -611,5 +611,7 @@ static inline struct dentry *d_next_sibling(const struct dentry *dentry)
 }
 
 void set_default_d_op(struct super_block *, const struct dentry_operations *);
+struct dentry *d_make_persistent(struct dentry *, struct inode *);
+void d_make_discardable(struct dentry *dentry);
 
 #endif	/* __LINUX_DCACHE_H */
-- 
cgit v1.2.3


From 23cbc7a795853bc7a8d0512b7c686ef879f6e909 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Mon, 26 Feb 2024 01:55:36 -0500
Subject: procfs: make /self and /thread_self dentries persistent

... and there's no need to remember those pointers anywhere - ->kill_sb()
no longer needs to bother since kill_anon_super() will take care of
them anyway and proc_pid_readdir() only wants the inumbers, which
we had in a couple of static variables all along.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 fs/proc/base.c          |  6 ++----
 fs/proc/internal.h      |  1 +
 fs/proc/root.c          | 14 ++++----------
 fs/proc/self.c          | 10 +++-------
 fs/proc/thread_self.c   | 11 +++--------
 include/linux/proc_fs.h |  2 --
 6 files changed, 13 insertions(+), 31 deletions(-)

(limited to 'include/linux')

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 6299878e3d97..869677a26332 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -3585,14 +3585,12 @@ int proc_pid_readdir(struct file *file, struct dir_context *ctx)
 		return 0;
 
 	if (pos == TGID_OFFSET - 2) {
-		struct inode *inode = d_inode(fs_info->proc_self);
-		if (!dir_emit(ctx, "self", 4, inode->i_ino, DT_LNK))
+		if (!dir_emit(ctx, "self", 4, self_inum, DT_LNK))
 			return 0;
 		ctx->pos = pos = pos + 1;
 	}
 	if (pos == TGID_OFFSET - 1) {
-		struct inode *inode = d_inode(fs_info->proc_thread_self);
-		if (!dir_emit(ctx, "thread-self", 11, inode->i_ino, DT_LNK))
+		if (!dir_emit(ctx, "thread-self", 11, thread_self_inum, DT_LNK))
 			return 0;
 		ctx->pos = pos = pos + 1;
 	}
diff --git a/fs/proc/internal.h b/fs/proc/internal.h
index d1598576506c..c1e8eb984da8 100644
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -373,6 +373,7 @@ static inline void proc_tty_init(void) {}
 extern struct proc_dir_entry proc_root;
 
 extern void proc_self_init(void);
+extern unsigned self_inum, thread_self_inum;
 
 /*
  * task_[no]mmu.c
diff --git a/fs/proc/root.c b/fs/proc/root.c
index 1e24e085c7d5..d8ca41d823e4 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -347,17 +347,11 @@ static void proc_kill_sb(struct super_block *sb)
 {
 	struct proc_fs_info *fs_info = proc_sb_info(sb);
 
-	if (!fs_info) {
-		kill_anon_super(sb);
-		return;
-	}
-
-	dput(fs_info->proc_self);
-	dput(fs_info->proc_thread_self);
-
 	kill_anon_super(sb);
-	put_pid_ns(fs_info->pid_ns);
-	kfree_rcu(fs_info, rcu);
+	if (fs_info) {
+		put_pid_ns(fs_info->pid_ns);
+		kfree_rcu(fs_info, rcu);
+	}
 }
 
 static struct file_system_type proc_fs_type = {
diff --git a/fs/proc/self.c b/fs/proc/self.c
index b46fbfd22681..62d2c0cfe35c 100644
--- a/fs/proc/self.c
+++ b/fs/proc/self.c
@@ -31,12 +31,11 @@ static const struct inode_operations proc_self_inode_operations = {
 	.get_link	= proc_self_get_link,
 };
 
-static unsigned self_inum __ro_after_init;
+unsigned self_inum __ro_after_init;
 
 int proc_setup_self(struct super_block *s)
 {
 	struct inode *root_inode = d_inode(s->s_root);
-	struct proc_fs_info *fs_info = proc_sb_info(s);
 	struct dentry *self;
 	int ret = -ENOMEM;
 
@@ -51,18 +50,15 @@ int proc_setup_self(struct super_block *s)
 			inode->i_uid = GLOBAL_ROOT_UID;
 			inode->i_gid = GLOBAL_ROOT_GID;
 			inode->i_op = &proc_self_inode_operations;
-			d_add(self, inode);
+			d_make_persistent(self, inode);
 			ret = 0;
-		} else {
-			dput(self);
 		}
+		dput(self);
 	}
 	inode_unlock(root_inode);
 
 	if (ret)
 		pr_err("proc_fill_super: can't allocate /proc/self\n");
-	else
-		fs_info->proc_self = self;
 
 	return ret;
 }
diff --git a/fs/proc/thread_self.c b/fs/proc/thread_self.c
index 0e5050d6ab64..d6113dbe58e0 100644
--- a/fs/proc/thread_self.c
+++ b/fs/proc/thread_self.c
@@ -31,12 +31,11 @@ static const struct inode_operations proc_thread_self_inode_operations = {
 	.get_link	= proc_thread_self_get_link,
 };
 
-static unsigned thread_self_inum __ro_after_init;
+unsigned thread_self_inum __ro_after_init;
 
 int proc_setup_thread_self(struct super_block *s)
 {
 	struct inode *root_inode = d_inode(s->s_root);
-	struct proc_fs_info *fs_info = proc_sb_info(s);
 	struct dentry *thread_self;
 	int ret = -ENOMEM;
 
@@ -51,19 +50,15 @@ int proc_setup_thread_self(struct super_block *s)
 			inode->i_uid = GLOBAL_ROOT_UID;
 			inode->i_gid = GLOBAL_ROOT_GID;
 			inode->i_op = &proc_thread_self_inode_operations;
-			d_add(thread_self, inode);
+			d_make_persistent(thread_self, inode);
 			ret = 0;
-		} else {
-			dput(thread_self);
 		}
+		dput(thread_self);
 	}
 	inode_unlock(root_inode);
 
 	if (ret)
 		pr_err("proc_fill_super: can't allocate /proc/thread-self\n");
-	else
-		fs_info->proc_thread_self = thread_self;
-
 	return ret;
 }
 
diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
index f139377f4b31..19d1c5e5f335 100644
--- a/include/linux/proc_fs.h
+++ b/include/linux/proc_fs.h
@@ -66,8 +66,6 @@ enum proc_pidonly {
 
 struct proc_fs_info {
 	struct pid_namespace *pid_ns;
-	struct dentry *proc_self;        /* For /proc/self */
-	struct dentry *proc_thread_self; /* For /proc/thread-self */
 	kgid_t pid_gid;
 	enum proc_hidepid hide_pid;
 	enum proc_pidonly pidonly;
-- 
cgit v1.2.3


From fc45aee66223253ec5547094d7552819914abdfb Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Mon, 10 Mar 2025 00:06:29 -0400
Subject: get rid of kill_litter_super()

Not used anymore.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 Documentation/filesystems/porting.rst |  7 +++++++
 fs/dcache.c                           | 21 ---------------------
 fs/internal.h                         |  1 -
 fs/super.c                            |  8 --------
 include/linux/dcache.h                |  1 -
 include/linux/fs.h                    |  1 -
 6 files changed, 7 insertions(+), 32 deletions(-)

(limited to 'include/linux')

diff --git a/Documentation/filesystems/porting.rst b/Documentation/filesystems/porting.rst
index 7233b04668fc..4921b3b0662a 100644
--- a/Documentation/filesystems/porting.rst
+++ b/Documentation/filesystems/porting.rst
@@ -1309,3 +1309,10 @@ a different length, use
 	vfs_parse_fs_qstr(fc, key, &QSTR_LEN(value, len))
 
 instead.
+
+---
+
+**mandatory**
+
+kill_litter_super() is gone; convert to DCACHE_PERSISTENT use (as all
+in-tree filesystems have done).
diff --git a/fs/dcache.c b/fs/dcache.c
index 3cc6c3876177..5ee2e78a91b3 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -3167,27 +3167,6 @@ bool is_subdir(struct dentry *new_dentry, struct dentry *old_dentry)
 }
 EXPORT_SYMBOL(is_subdir);
 
-static enum d_walk_ret d_genocide_kill(void *data, struct dentry *dentry)
-{
-	struct dentry *root = data;
-	if (dentry != root) {
-		if (d_unhashed(dentry) || !dentry->d_inode ||
-		    dentry->d_flags & DCACHE_PERSISTENT)
-			return D_WALK_SKIP;
-
-		if (!(dentry->d_flags & DCACHE_GENOCIDE)) {
-			dentry->d_flags |= DCACHE_GENOCIDE;
-			dentry->d_lockref.count--;
-		}
-	}
-	return D_WALK_CONTINUE;
-}
-
-void d_genocide(struct dentry *parent)
-{
-	d_walk(parent, parent, d_genocide_kill);
-}
-
 void d_mark_tmpfile(struct file *file, struct inode *inode)
 {
 	struct dentry *dentry = file->f_path.dentry;
diff --git a/fs/internal.h b/fs/internal.h
index 9b2b4d116880..144686af6c36 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -227,7 +227,6 @@ extern void shrink_dcache_for_umount(struct super_block *);
 extern struct dentry *__d_lookup(const struct dentry *, const struct qstr *);
 extern struct dentry *__d_lookup_rcu(const struct dentry *parent,
 				const struct qstr *name, unsigned *seq);
-extern void d_genocide(struct dentry *);
 
 /*
  * pipe.c
diff --git a/fs/super.c b/fs/super.c
index 5bab94fb7e03..ee001f684d2a 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -1284,14 +1284,6 @@ void kill_anon_super(struct super_block *sb)
 }
 EXPORT_SYMBOL(kill_anon_super);
 
-void kill_litter_super(struct super_block *sb)
-{
-	if (sb->s_root)
-		d_genocide(sb->s_root);
-	kill_anon_super(sb);
-}
-EXPORT_SYMBOL(kill_litter_super);
-
 int set_anon_super_fc(struct super_block *sb, struct fs_context *fc)
 {
 	return set_anon_super(sb, NULL);
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 6ec4066825e3..20a85144a00e 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -198,7 +198,6 @@ enum dentry_flags {
 	DCACHE_REFERENCED		= BIT(6),	/* Recently used, don't discard. */
 	DCACHE_DONTCACHE		= BIT(7),	/* Purge from memory on final dput() */
 	DCACHE_CANT_MOUNT		= BIT(8),
-	DCACHE_GENOCIDE			= BIT(9),
 	DCACHE_SHRINK_LIST		= BIT(10),
 	DCACHE_OP_WEAK_REVALIDATE	= BIT(11),
 	/*
diff --git a/include/linux/fs.h b/include/linux/fs.h
index f5037c556f61..95933ceaae51 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2728,7 +2728,6 @@ void retire_super(struct super_block *sb);
 void generic_shutdown_super(struct super_block *sb);
 void kill_block_super(struct super_block *sb);
 void kill_anon_super(struct super_block *sb);
-void kill_litter_super(struct super_block *sb);
 void deactivate_super(struct super_block *sb);
 void deactivate_locked_super(struct super_block *sb);
 int set_anon_super(struct super_block *s, void *data);
-- 
cgit v1.2.3


From ca459ca70f60ce05445845eca74c788b0d5ddb1b Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Sat, 25 Oct 2025 18:34:49 -0400
Subject: kill securityfs_recursive_remove()

it's an unused alias for securityfs_remove()

Acked-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 include/linux/security.h | 2 --
 1 file changed, 2 deletions(-)

(limited to 'include/linux')

diff --git a/include/linux/security.h b/include/linux/security.h
index 92ac3f27b973..9e710cfee744 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -2258,8 +2258,6 @@ static inline void securityfs_remove(struct dentry *dentry)
 
 #endif
 
-#define securityfs_recursive_remove securityfs_remove
-
 #ifdef CONFIG_BPF_SYSCALL
 union bpf_attr;
 struct bpf_map;
-- 
cgit v1.2.3


From eb028c33451af08bb34f45c6be6967ef1c98cbd1 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Mon, 27 Oct 2025 18:32:21 -0400
Subject: d_make_discardable(): warn if given a non-persistent dentry

At this point there are very few call chains that might lead to
d_make_discardable() on a dentry that hadn't been made persistent:
calls of simple_unlink() and simple_rmdir() in configfs and
apparmorfs.

Both filesystems do pin (part of) their contents in dcache, but
they are currently playing very unusual games with that.  Converting
them to more usual patterns might be possible, but it's definitely
going to be a long series of changes in both cases.

For now the easiest solution is to have both stop using simple_unlink()
and simple_rmdir() - that allows to make d_make_discardable() warn
when given a non-persistent dentry.

Rather than giving them full-blown private copies (with calls of
d_make_discardable() replaced with dput()), let's pull the parts of
simple_unlink() and simple_rmdir() that deal with timestamps and link
counts into separate helpers (__simple_unlink() and __simple_rmdir()
resp.) and have those used by configfs and apparmorfs.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 fs/configfs/dir.c              | 10 ++++++++--
 fs/configfs/inode.c            |  3 ++-
 fs/dcache.c                    |  9 +--------
 fs/libfs.c                     | 21 +++++++++++++++++----
 include/linux/fs.h             |  2 ++
 security/apparmor/apparmorfs.c | 13 +++++++++----
 6 files changed, 39 insertions(+), 19 deletions(-)

(limited to 'include/linux')

diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c
index 81f4f06bc87e..e8f2f44012e9 100644
--- a/fs/configfs/dir.c
+++ b/fs/configfs/dir.c
@@ -400,8 +400,14 @@ static void remove_dir(struct dentry * d)
 
 	configfs_remove_dirent(d);
 
-	if (d_really_is_positive(d))
-		simple_rmdir(d_inode(parent),d);
+	if (d_really_is_positive(d)) {
+		if (likely(simple_empty(d))) {
+			__simple_rmdir(d_inode(parent),d);
+			dput(d);
+		} else {
+			pr_warn("remove_dir (%pd): attributes remain", d);
+		}
+	}
 
 	pr_debug(" o %pd removing done (%d)\n", d, d_count(d));
 
diff --git a/fs/configfs/inode.c b/fs/configfs/inode.c
index 1d2e3a5738d1..bcda3372e141 100644
--- a/fs/configfs/inode.c
+++ b/fs/configfs/inode.c
@@ -211,7 +211,8 @@ void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
 			dget_dlock(dentry);
 			__d_drop(dentry);
 			spin_unlock(&dentry->d_lock);
-			simple_unlink(d_inode(parent), dentry);
+			__simple_unlink(d_inode(parent), dentry);
+			dput(dentry);
 		} else
 			spin_unlock(&dentry->d_lock);
 	}
diff --git a/fs/dcache.c b/fs/dcache.c
index 5ee2e78a91b3..824d620bb563 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -931,14 +931,7 @@ EXPORT_SYMBOL(dput);
 void d_make_discardable(struct dentry *dentry)
 {
 	spin_lock(&dentry->d_lock);
-	/*
-	 * By the end of the series we'll add
-	 * WARN_ON(!(dentry->d_flags & DCACHE_PERSISTENT);
-	 * here, but while object removal is done by a few common helpers,
-	 * object creation tends to be open-coded (if nothing else, new inode
-	 * needs to be set up), so adding a warning from the very beginning
-	 * would make for much messier patch series.
-	 */
+	WARN_ON(!(dentry->d_flags & DCACHE_PERSISTENT));
 	dentry->d_flags &= ~DCACHE_PERSISTENT;
 	dentry->d_lockref.count--;
 	rcu_read_lock();
diff --git a/fs/libfs.c b/fs/libfs.c
index 80f288a771e3..0aa630e7eb00 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -790,13 +790,27 @@ out:
 }
 EXPORT_SYMBOL(simple_empty);
 
-int simple_unlink(struct inode *dir, struct dentry *dentry)
+void __simple_unlink(struct inode *dir, struct dentry *dentry)
 {
 	struct inode *inode = d_inode(dentry);
 
 	inode_set_mtime_to_ts(dir,
 			      inode_set_ctime_to_ts(dir, inode_set_ctime_current(inode)));
 	drop_nlink(inode);
+}
+EXPORT_SYMBOL(__simple_unlink);
+
+void __simple_rmdir(struct inode *dir, struct dentry *dentry)
+{
+	drop_nlink(d_inode(dentry));
+	__simple_unlink(dir, dentry);
+	drop_nlink(dir);
+}
+EXPORT_SYMBOL(__simple_rmdir);
+
+int simple_unlink(struct inode *dir, struct dentry *dentry)
+{
+	__simple_unlink(dir, dentry);
 	d_make_discardable(dentry);
 	return 0;
 }
@@ -807,9 +821,8 @@ int simple_rmdir(struct inode *dir, struct dentry *dentry)
 	if (!simple_empty(dentry))
 		return -ENOTEMPTY;
 
-	drop_nlink(d_inode(dentry));
-	simple_unlink(dir, dentry);
-	drop_nlink(dir);
+	__simple_rmdir(dir, dentry);
+	d_make_discardable(dentry);
 	return 0;
 }
 EXPORT_SYMBOL(simple_rmdir);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 95933ceaae51..ef842adbd418 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3621,6 +3621,8 @@ extern int simple_open(struct inode *inode, struct file *file);
 extern int simple_link(struct dentry *, struct inode *, struct dentry *);
 extern int simple_unlink(struct inode *, struct dentry *);
 extern int simple_rmdir(struct inode *, struct dentry *);
+extern void __simple_unlink(struct inode *, struct dentry *);
+extern void __simple_rmdir(struct inode *, struct dentry *);
 void simple_rename_timestamp(struct inode *old_dir, struct dentry *old_dentry,
 			     struct inode *new_dir, struct dentry *new_dentry);
 extern int simple_rename_exchange(struct inode *old_dir, struct dentry *old_dentry,
diff --git a/security/apparmor/apparmorfs.c b/security/apparmor/apparmorfs.c
index 391a586d0557..9b9090d38ea2 100644
--- a/security/apparmor/apparmorfs.c
+++ b/security/apparmor/apparmorfs.c
@@ -358,10 +358,15 @@ static void aafs_remove(struct dentry *dentry)
 	dir = d_inode(dentry->d_parent);
 	inode_lock(dir);
 	if (simple_positive(dentry)) {
-		if (d_is_dir(dentry))
-			simple_rmdir(dir, dentry);
-		else
-			simple_unlink(dir, dentry);
+		if (d_is_dir(dentry)) {
+			if (!WARN_ON(!simple_empty(dentry))) {
+				__simple_rmdir(dir, dentry);
+				dput(dentry);
+			}
+		} else {
+			__simple_unlink(dir, dentry);
+			dput(dentry);
+		}
 		d_delete(dentry);
 		dput(dentry);
 	}
-- 
cgit v1.2.3