From acfde6e8abee6b23e53b08606f861d9124288030 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Sat, 4 Nov 2023 00:10:18 -0400
Subject: struct dentry: get rid of randomize_layout idiocy

This is beyond ridiculous.  There is a reason why that thing is
cacheline-aligned...

Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 include/linux/dcache.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'include')

diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 3da2f0545d5d..1d9f7f132055 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -111,7 +111,7 @@ struct dentry {
 		struct hlist_bl_node d_in_lookup_hash;	/* only for in-lookup ones */
 	 	struct rcu_head d_rcu;
 	} d_u;
-} __randomize_layout;
+};
 
 /*
  * dentry->d_lock spinlock nesting subclasses:
-- 
cgit v1.2.3


From 641c3ef5cb68a1426d42e6d3aba16db9bdfbe94f Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Fri, 10 Nov 2023 12:46:30 -0500
Subject: DCACHE_... ->d_flags bits: switch to BIT()

For bits 20..22 (inode type cached in ->d_flags) turn the definitions into
expressions like (5 << 20); everything else turns into straight use of
BIT()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 include/linux/dcache.h | 76 +++++++++++++++++++++++++-------------------------
 1 file changed, 38 insertions(+), 38 deletions(-)

(limited to 'include')

diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 1d9f7f132055..d9c314cc93b8 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -151,13 +151,13 @@ struct dentry_operations {
  */
 
 /* d_flags entries */
-#define DCACHE_OP_HASH			0x00000001
-#define DCACHE_OP_COMPARE		0x00000002
-#define DCACHE_OP_REVALIDATE		0x00000004
-#define DCACHE_OP_DELETE		0x00000008
-#define DCACHE_OP_PRUNE			0x00000010
+#define DCACHE_OP_HASH			BIT(0)
+#define DCACHE_OP_COMPARE		BIT(1)
+#define DCACHE_OP_REVALIDATE		BIT(2)
+#define DCACHE_OP_DELETE		BIT(3)
+#define DCACHE_OP_PRUNE			BIT(4)
 
-#define	DCACHE_DISCONNECTED		0x00000020
+#define	DCACHE_DISCONNECTED		BIT(5)
      /* This dentry is possibly not currently connected to the dcache tree, in
       * which case its parent will either be itself, or will have this flag as
       * well.  nfsd will not use a dentry with this bit set, but will first
@@ -168,50 +168,50 @@ struct dentry_operations {
       * dentry into place and return that dentry rather than the passed one,
       * typically using d_splice_alias. */
 
-#define DCACHE_REFERENCED		0x00000040 /* Recently used, don't discard. */
+#define DCACHE_REFERENCED		BIT(6) /* Recently used, don't discard. */
 
-#define DCACHE_DONTCACHE		0x00000080 /* Purge from memory on final dput() */
+#define DCACHE_DONTCACHE		BIT(7) /* Purge from memory on final dput() */
 
-#define DCACHE_CANT_MOUNT		0x00000100
-#define DCACHE_GENOCIDE			0x00000200
-#define DCACHE_SHRINK_LIST		0x00000400
+#define DCACHE_CANT_MOUNT		BIT(8)
+#define DCACHE_GENOCIDE			BIT(9)
+#define DCACHE_SHRINK_LIST		BIT(10)
 
-#define DCACHE_OP_WEAK_REVALIDATE	0x00000800
+#define DCACHE_OP_WEAK_REVALIDATE	BIT(11)
 
-#define DCACHE_NFSFS_RENAMED		0x00001000
+#define DCACHE_NFSFS_RENAMED		BIT(12)
      /* this dentry has been "silly renamed" and has to be deleted on the last
       * dput() */
-#define DCACHE_COOKIE			0x00002000 /* For use by dcookie subsystem */
-#define DCACHE_FSNOTIFY_PARENT_WATCHED	0x00004000
+#define DCACHE_COOKIE			BIT(13) /* For use by dcookie subsystem */
+#define DCACHE_FSNOTIFY_PARENT_WATCHED	BIT(14)
      /* Parent inode is watched by some fsnotify listener */
 
-#define DCACHE_DENTRY_KILLED		0x00008000
+#define DCACHE_DENTRY_KILLED		BIT(15)
 
-#define DCACHE_MOUNTED			0x00010000 /* is a mountpoint */
-#define DCACHE_NEED_AUTOMOUNT		0x00020000 /* handle automount on this dir */
-#define DCACHE_MANAGE_TRANSIT		0x00040000 /* manage transit from this dirent */
+#define DCACHE_MOUNTED			BIT(16) /* is a mountpoint */
+#define DCACHE_NEED_AUTOMOUNT		BIT(17) /* handle automount on this dir */
+#define DCACHE_MANAGE_TRANSIT		BIT(18) /* manage transit from this dirent */
 #define DCACHE_MANAGED_DENTRY \
 	(DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT)
 
-#define DCACHE_LRU_LIST			0x00080000
-
-#define DCACHE_ENTRY_TYPE		0x00700000
-#define DCACHE_MISS_TYPE		0x00000000 /* Negative dentry (maybe fallthru to nowhere) */
-#define DCACHE_WHITEOUT_TYPE		0x00100000 /* Whiteout dentry (stop pathwalk) */
-#define DCACHE_DIRECTORY_TYPE		0x00200000 /* Normal directory */
-#define DCACHE_AUTODIR_TYPE		0x00300000 /* Lookupless directory (presumed automount) */
-#define DCACHE_REGULAR_TYPE		0x00400000 /* Regular file type (or fallthru to such) */
-#define DCACHE_SPECIAL_TYPE		0x00500000 /* Other file type (or fallthru to such) */
-#define DCACHE_SYMLINK_TYPE		0x00600000 /* Symlink (or fallthru to such) */
-
-#define DCACHE_MAY_FREE			0x00800000
-#define DCACHE_FALLTHRU			0x01000000 /* Fall through to lower layer */
-#define DCACHE_NOKEY_NAME		0x02000000 /* Encrypted name encoded without key */
-#define DCACHE_OP_REAL			0x04000000
-
-#define DCACHE_PAR_LOOKUP		0x10000000 /* being looked up (with parent locked shared) */
-#define DCACHE_DENTRY_CURSOR		0x20000000
-#define DCACHE_NORCU			0x40000000 /* No RCU delay for freeing */
+#define DCACHE_LRU_LIST			BIT(19)
+
+#define DCACHE_ENTRY_TYPE		(7 << 20) /* bits 20..22 are for storing type: */
+#define DCACHE_MISS_TYPE		(0 << 20) /* Negative dentry (maybe fallthru to nowhere) */
+#define DCACHE_WHITEOUT_TYPE		(1 << 20) /* Whiteout dentry (stop pathwalk) */
+#define DCACHE_DIRECTORY_TYPE		(2 << 20) /* Normal directory */
+#define DCACHE_AUTODIR_TYPE		(3 << 20) /* Lookupless directory (presumed automount) */
+#define DCACHE_REGULAR_TYPE		(4 << 20) /* Regular file type (or fallthru to such) */
+#define DCACHE_SPECIAL_TYPE		(5 << 20) /* Other file type (or fallthru to such) */
+#define DCACHE_SYMLINK_TYPE		(6 << 20) /* Symlink (or fallthru to such) */
+
+#define DCACHE_MAY_FREE			BIT(23)
+#define DCACHE_FALLTHRU			BIT(24) /* Fall through to lower layer */
+#define DCACHE_NOKEY_NAME		BIT(25) /* Encrypted name encoded without key */
+#define DCACHE_OP_REAL			BIT(26)
+
+#define DCACHE_PAR_LOOKUP		BIT(28) /* being looked up (with parent locked shared) */
+#define DCACHE_DENTRY_CURSOR		BIT(29)
+#define DCACHE_NORCU			BIT(30) /* No RCU delay for freeing */
 
 extern seqlock_t rename_lock;
 
-- 
cgit v1.2.3


From 0bec65a80f1b1ebcda05286e539a204713b70353 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Fri, 10 Nov 2023 12:50:29 -0500
Subject: DCACHE_COOKIE: RIP

the last user gone in 2021...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 include/linux/dcache.h | 1 -
 1 file changed, 1 deletion(-)

(limited to 'include')

diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index d9c314cc93b8..92c0b2a1ae2e 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -181,7 +181,6 @@ struct dentry_operations {
 #define DCACHE_NFSFS_RENAMED		BIT(12)
      /* this dentry has been "silly renamed" and has to be deleted on the last
       * dput() */
-#define DCACHE_COOKIE			BIT(13) /* For use by dcookie subsystem */
 #define DCACHE_FSNOTIFY_PARENT_WATCHED	BIT(14)
      /* Parent inode is watched by some fsnotify listener */
 
-- 
cgit v1.2.3


From 8219cb58feddcf28909072015f4e17e29f68c41a Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Fri, 10 Nov 2023 14:32:05 -0500
Subject: kill d_{is,set}_fallthru()

Introduced in 2015 and never had any in-tree users...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 fs/dcache.c            | 20 ++------------------
 include/linux/dcache.h | 17 ++++-------------
 2 files changed, 6 insertions(+), 31 deletions(-)

(limited to 'include')

diff --git a/fs/dcache.c b/fs/dcache.c
index b8f1b54a1492..9f5b2b5c1e6d 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -344,7 +344,7 @@ static inline void __d_set_inode_and_type(struct dentry *dentry,
 
 	dentry->d_inode = inode;
 	flags = READ_ONCE(dentry->d_flags);
-	flags &= ~(DCACHE_ENTRY_TYPE | DCACHE_FALLTHRU);
+	flags &= ~DCACHE_ENTRY_TYPE;
 	flags |= type_flags;
 	smp_store_release(&dentry->d_flags, flags);
 }
@@ -353,7 +353,7 @@ static inline void __d_clear_type_and_inode(struct dentry *dentry)
 {
 	unsigned flags = READ_ONCE(dentry->d_flags);
 
-	flags &= ~(DCACHE_ENTRY_TYPE | DCACHE_FALLTHRU);
+	flags &= ~DCACHE_ENTRY_TYPE;
 	WRITE_ONCE(dentry->d_flags, flags);
 	dentry->d_inode = NULL;
 	if (dentry->d_flags & DCACHE_LRU_LIST)
@@ -1936,22 +1936,6 @@ void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op)
 }
 EXPORT_SYMBOL(d_set_d_op);
 
-
-/*
- * d_set_fallthru - Mark a dentry as falling through to a lower layer
- * @dentry - The dentry to mark
- *
- * Mark a dentry as falling through to the lower layer (as set with
- * d_pin_lower()).  This flag may be recorded on the medium.
- */
-void d_set_fallthru(struct dentry *dentry)
-{
-	spin_lock(&dentry->d_lock);
-	dentry->d_flags |= DCACHE_FALLTHRU;
-	spin_unlock(&dentry->d_lock);
-}
-EXPORT_SYMBOL(d_set_fallthru);
-
 static unsigned d_flags_for_inode(struct inode *inode)
 {
 	unsigned add_flags = DCACHE_REGULAR_TYPE;
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 92c0b2a1ae2e..8cd937bb2292 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -195,16 +195,15 @@ struct dentry_operations {
 #define DCACHE_LRU_LIST			BIT(19)
 
 #define DCACHE_ENTRY_TYPE		(7 << 20) /* bits 20..22 are for storing type: */
-#define DCACHE_MISS_TYPE		(0 << 20) /* Negative dentry (maybe fallthru to nowhere) */
+#define DCACHE_MISS_TYPE		(0 << 20) /* Negative dentry */
 #define DCACHE_WHITEOUT_TYPE		(1 << 20) /* Whiteout dentry (stop pathwalk) */
 #define DCACHE_DIRECTORY_TYPE		(2 << 20) /* Normal directory */
 #define DCACHE_AUTODIR_TYPE		(3 << 20) /* Lookupless directory (presumed automount) */
-#define DCACHE_REGULAR_TYPE		(4 << 20) /* Regular file type (or fallthru to such) */
-#define DCACHE_SPECIAL_TYPE		(5 << 20) /* Other file type (or fallthru to such) */
-#define DCACHE_SYMLINK_TYPE		(6 << 20) /* Symlink (or fallthru to such) */
+#define DCACHE_REGULAR_TYPE		(4 << 20) /* Regular file type */
+#define DCACHE_SPECIAL_TYPE		(5 << 20) /* Other file type */
+#define DCACHE_SYMLINK_TYPE		(6 << 20) /* Symlink */
 
 #define DCACHE_MAY_FREE			BIT(23)
-#define DCACHE_FALLTHRU			BIT(24) /* Fall through to lower layer */
 #define DCACHE_NOKEY_NAME		BIT(25) /* Encrypted name encoded without key */
 #define DCACHE_OP_REAL			BIT(26)
 
@@ -489,14 +488,6 @@ static inline int simple_positive(const struct dentry *dentry)
 	return d_really_is_positive(dentry) && !d_unhashed(dentry);
 }
 
-extern void d_set_fallthru(struct dentry *dentry);
-
-static inline bool d_is_fallthru(const struct dentry *dentry)
-{
-	return dentry->d_flags & DCACHE_FALLTHRU;
-}
-
-
 extern int sysctl_vfs_cache_pressure;
 
 static inline unsigned long vfs_pressure_ratio(unsigned long val)
-- 
cgit v1.2.3


From 0d486510f86eb8162022ed61e6dc424a10909a10 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Fri, 10 Nov 2023 15:22:40 -0500
Subject: dentry.h: trim externs

d_instantiate_unique() had been gone for 7 years; __d_lookup...()
and shrink_dcache_for_umount() are fs/internal.h fodder.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 fs/internal.h          | 4 ++++
 include/linux/dcache.h | 5 -----
 2 files changed, 4 insertions(+), 5 deletions(-)

(limited to 'include')

diff --git a/fs/internal.h b/fs/internal.h
index 58e43341aebf..9e9fc629f935 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -215,6 +215,10 @@ extern struct dentry * d_alloc_pseudo(struct super_block *, const struct qstr *)
 extern char *simple_dname(struct dentry *, char *, int);
 extern void dput_to_list(struct dentry *, struct list_head *);
 extern void shrink_dentry_list(struct list_head *);
+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);
 
 /*
  * pipe.c
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 8cd937bb2292..9706bf1dc5de 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -218,7 +218,6 @@ extern seqlock_t rename_lock;
  */
 extern void d_instantiate(struct dentry *, struct inode *);
 extern void d_instantiate_new(struct dentry *, struct inode *);
-extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *);
 extern struct dentry * d_instantiate_anon(struct dentry *, struct inode *);
 extern void __d_drop(struct dentry *dentry);
 extern void d_drop(struct dentry *dentry);
@@ -240,7 +239,6 @@ extern struct dentry * d_obtain_alias(struct inode *);
 extern struct dentry * d_obtain_root(struct inode *);
 extern void shrink_dcache_sb(struct super_block *);
 extern void shrink_dcache_parent(struct dentry *);
-extern void shrink_dcache_for_umount(struct super_block *);
 extern void d_invalidate(struct dentry *);
 
 /* only used at mount-time */
@@ -275,9 +273,6 @@ extern struct dentry *d_ancestor(struct dentry *, struct dentry *);
 /* appendix may either be NULL or be used for transname suffixes */
 extern struct dentry *d_lookup(const struct dentry *, const struct qstr *);
 extern struct dentry *d_hash_and_lookup(struct dentry *, struct qstr *);
-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);
 
 static inline unsigned d_count(const struct dentry *dentry)
 {
-- 
cgit v1.2.3


From 2fcd38f4de7256e2b5cb23ad22a6e3ebfea7dd18 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Fri, 10 Nov 2023 15:24:45 -0500
Subject: [software coproarchaeology] dentry.h: kill a mysterious comment

there's a strange comment in front of d_lookup() declaration:

/* appendix may either be NULL or be used for transname suffixes */

Looks like nobody had been curious enough to track its history;
it predates git, it predates bitkeeper and if you look through
the pre-BK trees, you finally arrive at this in 2.1.44-for-davem:
  /* appendix may either be NULL or be used for transname suffixes */
 -extern struct dentry * d_lookup(struct inode * dir, struct qstr * name,
 -                               struct qstr * appendix);
 +extern struct dentry * d_lookup(struct dentry * dir, struct qstr * name);
In other words, it refers to the third argument d_lookup() used to have
back then.  It had been introduced in 2.1.43-pre, on June 12 1997,
along with d_lookup(), only to be removed by July 4 1997, presumably
when the Cthulhu-awful thing it used to be used for (look for
CONFIG_TRANS_NAMES in 2.1.43-pre, and keep a heavy-duty barfbag
ready) had been, er, noticed and recognized for what it had been.

Despite the appendectomy, the comment remained.  Some things really
need to be put out of their misery...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 include/linux/dcache.h | 1 -
 1 file changed, 1 deletion(-)

(limited to 'include')

diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 9706bf1dc5de..a5e5e274eee0 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -270,7 +270,6 @@ extern void d_move(struct dentry *, struct dentry *);
 extern void d_exchange(struct dentry *, struct dentry *);
 extern struct dentry *d_ancestor(struct dentry *, struct dentry *);
 
-/* appendix may either be NULL or be used for transname suffixes */
 extern struct dentry *d_lookup(const struct dentry *, const struct qstr *);
 extern struct dentry *d_hash_and_lookup(struct dentry *, struct qstr *);
 
-- 
cgit v1.2.3


From 698f1e2b71736977b04f951e2e2ef1c9a80696ff Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Fri, 10 Nov 2023 16:19:59 -0500
Subject: kill d_backing_dentry()

no users left

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 include/linux/dcache.h | 15 ---------------
 1 file changed, 15 deletions(-)

(limited to 'include')

diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index a5e5e274eee0..fa0414cff85c 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -530,21 +530,6 @@ static inline struct inode *d_backing_inode(const struct dentry *upper)
 	return inode;
 }
 
-/**
- * d_backing_dentry - Get upper or lower dentry we should be using
- * @upper: The upper layer
- *
- * This is the helper that should be used to get the dentry of the inode that
- * will be used if this dentry were opened as a file.  It may be the upper
- * dentry or it may be a lower dentry pinned by the upper.
- *
- * Normal filesystems should not use this to access their own dentries.
- */
-static inline struct dentry *d_backing_dentry(struct dentry *upper)
-{
-	return upper;
-}
-
 /**
  * d_real - Return the real dentry
  * @dentry: the dentry to query
-- 
cgit v1.2.3


From da549bdd15c295c24b2ee7ffe7ad0f3877fa8a87 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Tue, 7 Nov 2023 02:00:39 -0500
Subject: dentry: switch the lists of children to hlist

Saves a pointer per struct dentry and actually makes the things less
clumsy.  Cleaned the d_walk() and dcache_readdir() a bit by use
of hlist_for_... iterators.

A couple of new helpers - d_first_child() and d_next_sibling(),
to make the expressions less awful.

Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 Documentation/filesystems/porting.rst     |  9 ++++
 arch/powerpc/platforms/cell/spufs/inode.c |  5 +-
 fs/afs/dynroot.c                          |  5 +-
 fs/autofs/expire.c                        |  7 +--
 fs/ceph/dir.c                             |  2 +-
 fs/ceph/mds_client.c                      |  2 +-
 fs/coda/cache.c                           |  2 +-
 fs/dcache.c                               | 76 +++++++++++++++----------------
 fs/libfs.c                                | 45 +++++++++---------
 fs/notify/fsnotify.c                      |  2 +-
 fs/tracefs/inode.c                        | 34 ++++++--------
 include/linux/dcache.h                    | 20 ++++++--
 12 files changed, 108 insertions(+), 101 deletions(-)

(limited to 'include')

diff --git a/Documentation/filesystems/porting.rst b/Documentation/filesystems/porting.rst
index 878e72b2f8b7..331405f4b29f 100644
--- a/Documentation/filesystems/porting.rst
+++ b/Documentation/filesystems/porting.rst
@@ -1061,3 +1061,12 @@ export_operations ->encode_fh() no longer has a default implementation to
 encode FILEID_INO32_GEN* file handles.
 Filesystems that used the default implementation may use the generic helper
 generic_encode_ino32_fh() explicitly.
+
+---
+
+**mandatory**
+
+The list of children anchored in parent dentry got turned into hlist now.
+Field names got changed (->d_children/->d_sib instead of ->d_subdirs/->d_child
+for anchor/entries resp.), so any affected places will be immediately caught
+by compiler.
diff --git a/arch/powerpc/platforms/cell/spufs/inode.c b/arch/powerpc/platforms/cell/spufs/inode.c
index 10c1320adfd0..030de2b8c145 100644
--- a/arch/powerpc/platforms/cell/spufs/inode.c
+++ b/arch/powerpc/platforms/cell/spufs/inode.c
@@ -145,10 +145,11 @@ spufs_evict_inode(struct inode *inode)
 
 static void spufs_prune_dir(struct dentry *dir)
 {
-	struct dentry *dentry, *tmp;
+	struct dentry *dentry;
+	struct hlist_node *n;
 
 	inode_lock(d_inode(dir));
-	list_for_each_entry_safe(dentry, tmp, &dir->d_subdirs, d_child) {
+	hlist_for_each_entry_safe(dentry, n, &dir->d_children, d_sib) {
 		spin_lock(&dentry->d_lock);
 		if (simple_positive(dentry)) {
 			dget_dlock(dentry);
diff --git a/fs/afs/dynroot.c b/fs/afs/dynroot.c
index 4d04ef2d3ae7..fe45462834cc 100644
--- a/fs/afs/dynroot.c
+++ b/fs/afs/dynroot.c
@@ -370,7 +370,7 @@ error:
 void afs_dynroot_depopulate(struct super_block *sb)
 {
 	struct afs_net *net = afs_sb2net(sb);
-	struct dentry *root = sb->s_root, *subdir, *tmp;
+	struct dentry *root = sb->s_root, *subdir;
 
 	/* Prevent more subdirs from being created */
 	mutex_lock(&net->proc_cells_lock);
@@ -379,10 +379,11 @@ void afs_dynroot_depopulate(struct super_block *sb)
 	mutex_unlock(&net->proc_cells_lock);
 
 	if (root) {
+		struct hlist_node *n;
 		inode_lock(root->d_inode);
 
 		/* Remove all the pins for dirs created for manually added cells */
-		list_for_each_entry_safe(subdir, tmp, &root->d_subdirs, d_child) {
+		hlist_for_each_entry_safe(subdir, n, &root->d_children, d_sib) {
 			if (subdir->d_fsdata) {
 				subdir->d_fsdata = NULL;
 				dput(subdir);
diff --git a/fs/autofs/expire.c b/fs/autofs/expire.c
index 038b3d2d9f57..39d8c84c16f4 100644
--- a/fs/autofs/expire.c
+++ b/fs/autofs/expire.c
@@ -73,12 +73,9 @@ done:
 /* p->d_lock held */
 static struct dentry *positive_after(struct dentry *p, struct dentry *child)
 {
-	if (child)
-		child = list_next_entry(child, d_child);
-	else
-		child = list_first_entry(&p->d_subdirs, struct dentry, d_child);
+	child = child ? d_next_sibling(child) : d_first_child(p);
 
-	list_for_each_entry_from(child, &p->d_subdirs, d_child) {
+	hlist_for_each_entry_from(child, d_sib) {
 		spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
 		if (simple_positive(child)) {
 			dget_dlock(child);
diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index 91709934c8b1..678596684596 100644
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -174,7 +174,7 @@ __dcache_find_get_entry(struct dentry *parent, u64 idx,
 /*
  * When possible, we try to satisfy a readdir by peeking at the
  * dcache.  We make this work by carefully ordering dentries on
- * d_child when we initially get results back from the MDS, and
+ * d_children 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.
  *
diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index d95eb525519a..02ebfabfc8ee 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -2128,7 +2128,7 @@ static bool drop_negative_children(struct dentry *dentry)
 		goto out;
 
 	spin_lock(&dentry->d_lock);
-	list_for_each_entry(child, &dentry->d_subdirs, d_child) {
+	hlist_for_each_entry(child, &dentry->d_children, d_sib) {
 		if (d_really_is_positive(child)) {
 			all_negative = false;
 			break;
diff --git a/fs/coda/cache.c b/fs/coda/cache.c
index d6254cf9f397..970f0022ec52 100644
--- a/fs/coda/cache.c
+++ b/fs/coda/cache.c
@@ -93,7 +93,7 @@ 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_child) {
+	hlist_for_each_entry(de, &parent->d_children, d_sib) {
 		struct inode *inode = d_inode_rcu(de);
 		/* don't know what to do with negative dentries */
 		if (inode)
diff --git a/fs/dcache.c b/fs/dcache.c
index c82ae731df9a..59f76c9a15d1 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -51,8 +51,8 @@
  *   - d_lru
  *   - d_count
  *   - d_unhashed()
- *   - d_parent and d_subdirs
- *   - childrens' d_child and d_parent
+ *   - d_parent and d_chilren
+ *   - childrens' d_sib and d_parent
  *   - d_u.d_alias, d_inode
  *
  * Ordering:
@@ -537,7 +537,7 @@ void d_drop(struct dentry *dentry)
 }
 EXPORT_SYMBOL(d_drop);
 
-static inline void dentry_unlist(struct dentry *dentry, struct dentry *parent)
+static inline void dentry_unlist(struct dentry *dentry)
 {
 	struct dentry *next;
 	/*
@@ -545,12 +545,12 @@ static inline void dentry_unlist(struct dentry *dentry, struct dentry *parent)
 	 * attached to the dentry tree
 	 */
 	dentry->d_flags |= DCACHE_DENTRY_KILLED;
-	if (unlikely(list_empty(&dentry->d_child)))
+	if (unlikely(hlist_unhashed(&dentry->d_sib)))
 		return;
-	__list_del_entry(&dentry->d_child);
+	__hlist_del(&dentry->d_sib);
 	/*
 	 * Cursors can move around the list of children.  While we'd been
-	 * a normal list member, it didn't matter - ->d_child.next would've
+	 * a normal list member, it didn't matter - ->d_sib.next would've
 	 * been updated.  However, from now on it won't be and for the
 	 * things like d_walk() it might end up with a nasty surprise.
 	 * Normally d_walk() doesn't care about cursors moving around -
@@ -558,20 +558,20 @@ static inline void dentry_unlist(struct dentry *dentry, struct dentry *parent)
 	 * of its own, we get through it without ever unlocking the parent.
 	 * There is one exception, though - if we ascend from a child that
 	 * gets killed as soon as we unlock it, the next sibling is found
-	 * using the value left in its ->d_child.next.  And if _that_
+	 * using the value left in its ->d_sib.next.  And if _that_
 	 * pointed to a cursor, and cursor got moved (e.g. by lseek())
 	 * before d_walk() regains parent->d_lock, we'll end up skipping
 	 * everything the cursor had been moved past.
 	 *
-	 * Solution: make sure that the pointer left behind in ->d_child.next
+	 * Solution: make sure that the pointer left behind in ->d_sib.next
 	 * points to something that won't be moving around.  I.e. skip the
 	 * cursors.
 	 */
-	while (dentry->d_child.next != &parent->d_subdirs) {
-		next = list_entry(dentry->d_child.next, struct dentry, d_child);
+	while (dentry->d_sib.next) {
+		next = hlist_entry(dentry->d_sib.next, struct dentry, d_sib);
 		if (likely(!(next->d_flags & DCACHE_DENTRY_CURSOR)))
 			break;
-		dentry->d_child.next = next->d_child.next;
+		dentry->d_sib.next = next->d_sib.next;
 	}
 }
 
@@ -600,7 +600,7 @@ static void __dentry_kill(struct dentry *dentry)
 	}
 	/* if it was on the hash then remove it */
 	__d_drop(dentry);
-	dentry_unlist(dentry, parent);
+	dentry_unlist(dentry);
 	if (parent)
 		spin_unlock(&parent->d_lock);
 	if (dentry->d_inode)
@@ -1348,8 +1348,7 @@ enum d_walk_ret {
 static void d_walk(struct dentry *parent, void *data,
 		   enum d_walk_ret (*enter)(void *, struct dentry *))
 {
-	struct dentry *this_parent;
-	struct list_head *next;
+	struct dentry *this_parent, *dentry;
 	unsigned seq = 0;
 	enum d_walk_ret ret;
 	bool retry = true;
@@ -1371,13 +1370,9 @@ again:
 		break;
 	}
 repeat:
-	next = this_parent->d_subdirs.next;
+	dentry = d_first_child(this_parent);
 resume:
-	while (next != &this_parent->d_subdirs) {
-		struct list_head *tmp = next;
-		struct dentry *dentry = list_entry(tmp, struct dentry, d_child);
-		next = tmp->next;
-
+	hlist_for_each_entry_from(dentry, d_sib) {
 		if (unlikely(dentry->d_flags & DCACHE_DENTRY_CURSOR))
 			continue;
 
@@ -1398,7 +1393,7 @@ resume:
 			continue;
 		}
 
-		if (!list_empty(&dentry->d_subdirs)) {
+		if (!hlist_empty(&dentry->d_children)) {
 			spin_unlock(&this_parent->d_lock);
 			spin_release(&dentry->d_lock.dep_map, _RET_IP_);
 			this_parent = dentry;
@@ -1413,24 +1408,23 @@ resume:
 	rcu_read_lock();
 ascend:
 	if (this_parent != parent) {
-		struct dentry *child = this_parent;
-		this_parent = child->d_parent;
+		dentry = this_parent;
+		this_parent = dentry->d_parent;
 
-		spin_unlock(&child->d_lock);
+		spin_unlock(&dentry->d_lock);
 		spin_lock(&this_parent->d_lock);
 
 		/* might go back up the wrong parent if we have had a rename. */
 		if (need_seqretry(&rename_lock, seq))
 			goto rename_retry;
 		/* go into the first sibling still alive */
-		do {
-			next = child->d_child.next;
-			if (next == &this_parent->d_subdirs)
-				goto ascend;
-			child = list_entry(next, struct dentry, d_child);
-		} while (unlikely(child->d_flags & DCACHE_DENTRY_KILLED));
-		rcu_read_unlock();
-		goto resume;
+		hlist_for_each_entry_continue(dentry, d_sib) {
+			if (likely(!(dentry->d_flags & DCACHE_DENTRY_KILLED))) {
+				rcu_read_unlock();
+				goto resume;
+			}
+		}
+		goto ascend;
 	}
 	if (need_seqretry(&rename_lock, seq))
 		goto rename_retry;
@@ -1530,7 +1524,7 @@ out:
  * Search the dentry child list of the specified parent,
  * and move any unused dentries to the end of the unused
  * list for prune_dcache(). We descend to the next level
- * whenever the d_subdirs list is non-empty and continue
+ * whenever the d_children list is non-empty and continue
  * searching.
  *
  * It returns zero iff there are no unused children,
@@ -1657,7 +1651,7 @@ EXPORT_SYMBOL(shrink_dcache_parent);
 static enum d_walk_ret umount_check(void *_data, struct dentry *dentry)
 {
 	/* it has busy descendents; complain about those instead */
-	if (!list_empty(&dentry->d_subdirs))
+	if (!hlist_empty(&dentry->d_children))
 		return D_WALK_CONTINUE;
 
 	/* root with refcount 1 is fine */
@@ -1814,9 +1808,9 @@ static struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name)
 	dentry->d_fsdata = NULL;
 	INIT_HLIST_BL_NODE(&dentry->d_hash);
 	INIT_LIST_HEAD(&dentry->d_lru);
-	INIT_LIST_HEAD(&dentry->d_subdirs);
+	INIT_HLIST_HEAD(&dentry->d_children);
 	INIT_HLIST_NODE(&dentry->d_u.d_alias);
-	INIT_LIST_HEAD(&dentry->d_child);
+	INIT_HLIST_NODE(&dentry->d_sib);
 	d_set_d_op(dentry, dentry->d_sb->s_d_op);
 
 	if (dentry->d_op && dentry->d_op->d_init) {
@@ -1855,7 +1849,7 @@ struct dentry *d_alloc(struct dentry * parent, const struct qstr *name)
 	 */
 	__dget_dlock(parent);
 	dentry->d_parent = parent;
-	list_add(&dentry->d_child, &parent->d_subdirs);
+	hlist_add_head(&dentry->d_sib, &parent->d_children);
 	spin_unlock(&parent->d_lock);
 
 	return dentry;
@@ -2993,11 +2987,15 @@ static void __d_move(struct dentry *dentry, struct dentry *target,
 	} else {
 		target->d_parent = old_parent;
 		swap_names(dentry, target);
-		list_move(&target->d_child, &target->d_parent->d_subdirs);
+		if (!hlist_unhashed(&target->d_sib))
+			__hlist_del(&target->d_sib);
+		hlist_add_head(&target->d_sib, &target->d_parent->d_children);
 		__d_rehash(target);
 		fsnotify_update_flags(target);
 	}
-	list_move(&dentry->d_child, &dentry->d_parent->d_subdirs);
+	if (!hlist_unhashed(&dentry->d_sib))
+		__hlist_del(&dentry->d_sib);
+	hlist_add_head(&dentry->d_sib, &dentry->d_parent->d_children);
 	__d_rehash(dentry);
 	fsnotify_update_flags(dentry);
 	fscrypt_handle_d_move(dentry);
diff --git a/fs/libfs.c b/fs/libfs.c
index e9440d55073c..46c9177769c1 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -104,15 +104,16 @@ EXPORT_SYMBOL(dcache_dir_close);
  * If no such element exists, NULL is returned.
  */
 static struct dentry *scan_positives(struct dentry *cursor,
-					struct list_head *p,
+					struct hlist_node **p,
 					loff_t count,
 					struct dentry *last)
 {
 	struct dentry *dentry = cursor->d_parent, *found = NULL;
 
 	spin_lock(&dentry->d_lock);
-	while ((p = p->next) != &dentry->d_subdirs) {
-		struct dentry *d = list_entry(p, struct dentry, d_child);
+	while (*p) {
+		struct dentry *d = hlist_entry(*p, struct dentry, d_sib);
+		p = &d->d_sib.next;
 		// we must at least skip cursors, to avoid livelocks
 		if (d->d_flags & DCACHE_DENTRY_CURSOR)
 			continue;
@@ -126,8 +127,10 @@ static struct dentry *scan_positives(struct dentry *cursor,
 			count = 1;
 		}
 		if (need_resched()) {
-			list_move(&cursor->d_child, p);
-			p = &cursor->d_child;
+			if (!hlist_unhashed(&cursor->d_sib))
+				__hlist_del(&cursor->d_sib);
+			hlist_add_behind(&cursor->d_sib, &d->d_sib);
+			p = &cursor->d_sib.next;
 			spin_unlock(&dentry->d_lock);
 			cond_resched();
 			spin_lock(&dentry->d_lock);
@@ -159,13 +162,12 @@ loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence)
 		inode_lock_shared(dentry->d_inode);
 
 		if (offset > 2)
-			to = scan_positives(cursor, &dentry->d_subdirs,
+			to = scan_positives(cursor, &dentry->d_children.first,
 					    offset - 2, NULL);
 		spin_lock(&dentry->d_lock);
+		hlist_del_init(&cursor->d_sib);
 		if (to)
-			list_move(&cursor->d_child, &to->d_child);
-		else
-			list_del_init(&cursor->d_child);
+			hlist_add_behind(&cursor->d_sib, &to->d_sib);
 		spin_unlock(&dentry->d_lock);
 		dput(to);
 
@@ -187,19 +189,16 @@ 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 *anchor = &dentry->d_subdirs;
 	struct dentry *next = NULL;
-	struct list_head *p;
+	struct hlist_node **p;
 
 	if (!dir_emit_dots(file, ctx))
 		return 0;
 
 	if (ctx->pos == 2)
-		p = anchor;
-	else if (!list_empty(&cursor->d_child))
-		p = &cursor->d_child;
+		p = &dentry->d_children.first;
 	else
-		return 0;
+		p = &cursor->d_sib.next;
 
 	while ((next = scan_positives(cursor, p, 1, next)) != NULL) {
 		if (!dir_emit(ctx, next->d_name.name, next->d_name.len,
@@ -207,13 +206,12 @@ int dcache_readdir(struct file *file, struct dir_context *ctx)
 			      fs_umode_to_dtype(d_inode(next)->i_mode)))
 			break;
 		ctx->pos++;
-		p = &next->d_child;
+		p = &next->d_sib.next;
 	}
 	spin_lock(&dentry->d_lock);
+	hlist_del_init(&cursor->d_sib);
 	if (next)
-		list_move_tail(&cursor->d_child, &next->d_child);
-	else
-		list_del_init(&cursor->d_child);
+		hlist_add_before(&cursor->d_sib, &next->d_sib);
 	spin_unlock(&dentry->d_lock);
 	dput(next);
 
@@ -492,12 +490,11 @@ const struct file_operations simple_offset_dir_operations = {
 
 static struct dentry *find_next_child(struct dentry *parent, struct dentry *prev)
 {
-	struct dentry *child = NULL;
-	struct list_head *p = prev ? &prev->d_child : &parent->d_subdirs;
+	struct dentry *child = NULL, *d;
 
 	spin_lock(&parent->d_lock);
-	while ((p = p->next) != &parent->d_subdirs) {
-		struct dentry *d = container_of(p, struct dentry, d_child);
+	d = prev ? d_next_sibling(prev) : d_first_child(parent);
+	hlist_for_each_entry_from(d, d_sib) {
 		if (simple_positive(d)) {
 			spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED);
 			if (simple_positive(d))
@@ -658,7 +655,7 @@ int simple_empty(struct dentry *dentry)
 	int ret = 0;
 
 	spin_lock(&dentry->d_lock);
-	list_for_each_entry(child, &dentry->d_subdirs, d_child) {
+	hlist_for_each_entry(child, &dentry->d_children, d_sib) {
 		spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
 		if (simple_positive(child)) {
 			spin_unlock(&child->d_lock);
diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
index 7974e91ffe13..8bfd690e9f10 100644
--- a/fs/notify/fsnotify.c
+++ b/fs/notify/fsnotify.c
@@ -124,7 +124,7 @@ void __fsnotify_update_child_dentry_flags(struct inode *inode)
 		 * 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_child) {
+		hlist_for_each_entry(child, &alias->d_children, d_sib) {
 			if (!child->d_inode)
 				continue;
 
diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c
index 5b54948514fe..61ca5fcf10f9 100644
--- a/fs/tracefs/inode.c
+++ b/fs/tracefs/inode.c
@@ -199,26 +199,21 @@ static void change_gid(struct dentry *dentry, kgid_t gid)
  */
 static void set_gid(struct dentry *parent, kgid_t gid)
 {
-	struct dentry *this_parent;
-	struct list_head *next;
+	struct dentry *this_parent, *dentry;
 
 	this_parent = parent;
 	spin_lock(&this_parent->d_lock);
 
 	change_gid(this_parent, gid);
 repeat:
-	next = this_parent->d_subdirs.next;
+	dentry = d_first_child(this_parent);
 resume:
-	while (next != &this_parent->d_subdirs) {
-		struct list_head *tmp = next;
-		struct dentry *dentry = list_entry(tmp, struct dentry, d_child);
-		next = tmp->next;
-
+	hlist_for_each_entry_from(dentry, d_sib) {
 		spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
 
 		change_gid(dentry, gid);
 
-		if (!list_empty(&dentry->d_subdirs)) {
+		if (!hlist_empty(&dentry->d_children)) {
 			spin_unlock(&this_parent->d_lock);
 			spin_release(&dentry->d_lock.dep_map, _RET_IP_);
 			this_parent = dentry;
@@ -233,21 +228,20 @@ resume:
 	rcu_read_lock();
 ascend:
 	if (this_parent != parent) {
-		struct dentry *child = this_parent;
-		this_parent = child->d_parent;
+		dentry = this_parent;
+		this_parent = dentry->d_parent;
 
-		spin_unlock(&child->d_lock);
+		spin_unlock(&dentry->d_lock);
 		spin_lock(&this_parent->d_lock);
 
 		/* go into the first sibling still alive */
-		do {
-			next = child->d_child.next;
-			if (next == &this_parent->d_subdirs)
-				goto ascend;
-			child = list_entry(next, struct dentry, d_child);
-		} while (unlikely(child->d_flags & DCACHE_DENTRY_KILLED));
-		rcu_read_unlock();
-		goto resume;
+		hlist_for_each_entry_continue(dentry, d_sib) {
+			if (likely(!(dentry->d_flags & DCACHE_DENTRY_KILLED))) {
+				rcu_read_unlock();
+				goto resume;
+			}
+		}
+		goto ascend;
 	}
 	rcu_read_unlock();
 	spin_unlock(&this_parent->d_lock);
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 3da2f0545d5d..0e397a0c519c 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -68,12 +68,12 @@ extern const struct qstr dotdot_name;
  * large memory footprint increase).
  */
 #ifdef CONFIG_64BIT
-# define DNAME_INLINE_LEN 32 /* 192 bytes */
+# define DNAME_INLINE_LEN 40 /* 192 bytes */
 #else
 # ifdef CONFIG_SMP
-#  define DNAME_INLINE_LEN 36 /* 128 bytes */
-# else
 #  define DNAME_INLINE_LEN 40 /* 128 bytes */
+# else
+#  define DNAME_INLINE_LEN 44 /* 128 bytes */
 # endif
 #endif
 
@@ -101,8 +101,8 @@ struct dentry {
 		struct list_head d_lru;		/* LRU list */
 		wait_queue_head_t *d_wait;	/* in-lookup ones only */
 	};
-	struct list_head d_child;	/* child of parent list */
-	struct list_head d_subdirs;	/* our children */
+	struct hlist_node d_sib;	/* child of parent list */
+	struct hlist_head d_children;	/* our children */
 	/*
 	 * d_alias and d_rcu can share memory
 	 */
@@ -600,4 +600,14 @@ struct name_snapshot {
 void take_dentry_name_snapshot(struct name_snapshot *, struct dentry *);
 void release_dentry_name_snapshot(struct name_snapshot *);
 
+static inline struct dentry *d_first_child(const struct dentry *dentry)
+{
+	return hlist_entry_safe(dentry->d_children.first, struct dentry, d_sib);
+}
+
+static inline struct dentry *d_next_sibling(const struct dentry *dentry)
+{
+	return hlist_entry_safe(dentry->d_sib.next, struct dentry, d_sib);
+}
+
 #endif	/* __LINUX_DCACHE_H */
-- 
cgit v1.2.3


From f2824db1b49f947ba6e208ddf02edf4b1391480a Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Sat, 18 Nov 2023 16:42:43 -0500
Subject: kill d_instantate_anon(), fold __d_instantiate_anon() into remaining
 caller

now that the only user of d_instantiate_anon() is gone...
[braino fix folded - kudos to Dan Carpenter]

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 fs/dcache.c            | 90 ++++++++++++++++++++------------------------------
 include/linux/dcache.h |  1 -
 2 files changed, 35 insertions(+), 56 deletions(-)

(limited to 'include')

diff --git a/fs/dcache.c b/fs/dcache.c
index 9f5b2b5c1e6d..6c520eda131f 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2054,75 +2054,55 @@ struct dentry *d_make_root(struct inode *root_inode)
 }
 EXPORT_SYMBOL(d_make_root);
 
-static struct dentry *__d_instantiate_anon(struct dentry *dentry,
-					   struct inode *inode,
-					   bool disconnected)
-{
-	struct dentry *res;
-	unsigned add_flags;
-
-	security_d_instantiate(dentry, inode);
-	spin_lock(&inode->i_lock);
-	res = __d_find_any_alias(inode);
-	if (res) {
-		spin_unlock(&inode->i_lock);
-		dput(dentry);
-		goto out_iput;
-	}
-
-	/* attach a disconnected dentry */
-	add_flags = d_flags_for_inode(inode);
-
-	if (disconnected)
-		add_flags |= DCACHE_DISCONNECTED;
-
-	spin_lock(&dentry->d_lock);
-	__d_set_inode_and_type(dentry, inode, add_flags);
-	hlist_add_head(&dentry->d_u.d_alias, &inode->i_dentry);
-	if (!disconnected) {
-		hlist_bl_lock(&dentry->d_sb->s_roots);
-		hlist_bl_add_head(&dentry->d_hash, &dentry->d_sb->s_roots);
-		hlist_bl_unlock(&dentry->d_sb->s_roots);
-	}
-	spin_unlock(&dentry->d_lock);
-	spin_unlock(&inode->i_lock);
-
-	return dentry;
-
- out_iput:
-	iput(inode);
-	return res;
-}
-
-struct dentry *d_instantiate_anon(struct dentry *dentry, struct inode *inode)
-{
-	return __d_instantiate_anon(dentry, inode, true);
-}
-EXPORT_SYMBOL(d_instantiate_anon);
-
 static struct dentry *__d_obtain_alias(struct inode *inode, bool disconnected)
 {
-	struct dentry *tmp;
-	struct dentry *res;
+	struct super_block *sb;
+	struct dentry *new, *res;
 
 	if (!inode)
 		return ERR_PTR(-ESTALE);
 	if (IS_ERR(inode))
 		return ERR_CAST(inode);
 
-	res = d_find_any_alias(inode);
+	sb = inode->i_sb;
+
+	res = d_find_any_alias(inode); /* existing alias? */
 	if (res)
-		goto out_iput;
+		goto out;
 
-	tmp = d_alloc_anon(inode->i_sb);
-	if (!tmp) {
+	new = d_alloc_anon(sb);
+	if (!new) {
 		res = ERR_PTR(-ENOMEM);
-		goto out_iput;
+		goto out;
 	}
 
-	return __d_instantiate_anon(tmp, inode, disconnected);
+	security_d_instantiate(new, inode);
+	spin_lock(&inode->i_lock);
+	res = __d_find_any_alias(inode); /* recheck under lock */
+	if (likely(!res)) { /* still no alias, attach a disconnected dentry */
+		unsigned add_flags = d_flags_for_inode(inode);
+
+		if (disconnected)
+			add_flags |= DCACHE_DISCONNECTED;
+
+		spin_lock(&new->d_lock);
+		__d_set_inode_and_type(new, inode, add_flags);
+		hlist_add_head(&new->d_u.d_alias, &inode->i_dentry);
+		if (!disconnected) {
+			hlist_bl_lock(&sb->s_roots);
+			hlist_bl_add_head(&new->d_hash, &sb->s_roots);
+			hlist_bl_unlock(&sb->s_roots);
+		}
+		spin_unlock(&new->d_lock);
+		spin_unlock(&inode->i_lock);
+		inode = NULL; /* consumed by new->d_inode */
+		res = new;
+	} else {
+		spin_unlock(&inode->i_lock);
+		dput(new);
+	}
 
-out_iput:
+ out:
 	iput(inode);
 	return res;
 }
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index fa0414cff85c..8c5e3bdf1147 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -218,7 +218,6 @@ extern seqlock_t rename_lock;
  */
 extern void d_instantiate(struct dentry *, struct inode *);
 extern void d_instantiate_new(struct dentry *, struct inode *);
-extern struct dentry * d_instantiate_anon(struct dentry *, struct inode *);
 extern void __d_drop(struct dentry *dentry);
 extern void d_drop(struct dentry *dentry);
 extern void d_delete(struct dentry *);
-- 
cgit v1.2.3


From 8a54b38f3e5ced6cc4b246b8e54bd0f50deceaa8 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Sat, 11 Nov 2023 16:01:27 -0500
Subject: d_genocide(): move the extern into fs/internal.h

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 fs/internal.h          | 1 +
 include/linux/dcache.h | 3 ---
 2 files changed, 1 insertion(+), 3 deletions(-)

(limited to 'include')

diff --git a/fs/internal.h b/fs/internal.h
index 9e9fc629f935..d9a920e2636e 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -219,6 +219,7 @@ 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/include/linux/dcache.h b/include/linux/dcache.h
index 8c5e3bdf1147..b4324d47f249 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -243,9 +243,6 @@ extern void d_invalidate(struct dentry *);
 /* only used at mount-time */
 extern struct dentry * d_make_root(struct inode *);
 
-/* <clickety>-<click> the ramfs-type tree */
-extern void d_genocide(struct dentry *);
-
 extern void d_mark_tmpfile(struct file *, struct inode *);
 extern void d_tmpfile(struct file *, struct inode *);
 
-- 
cgit v1.2.3


From 57851607326a2beef21e67f83f4f53a90df8445a Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Sun, 12 Nov 2023 21:38:48 -0500
Subject: get rid of DCACHE_GENOCIDE

... now that we never call d_genocide() other than from kill_litter_super()

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

(limited to 'include')

diff --git a/fs/dcache.c b/fs/dcache.c
index 5947556b6e90..8473c8f0ce22 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -3198,10 +3198,7 @@ static enum d_walk_ret d_genocide_kill(void *data, struct dentry *dentry)
 		if (d_unhashed(dentry) || !dentry->d_inode)
 			return D_WALK_SKIP;
 
-		if (!(dentry->d_flags & DCACHE_GENOCIDE)) {
-			dentry->d_flags |= DCACHE_GENOCIDE;
-			dentry->d_lockref.count--;
-		}
+		dentry->d_lockref.count--;
 	}
 	return D_WALK_CONTINUE;
 }
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index b4324d47f249..981f529c6cb5 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -173,7 +173,6 @@ struct dentry_operations {
 #define DCACHE_DONTCACHE		BIT(7) /* Purge from memory on final dput() */
 
 #define DCACHE_CANT_MOUNT		BIT(8)
-#define DCACHE_GENOCIDE			BIT(9)
 #define DCACHE_SHRINK_LIST		BIT(10)
 
 #define DCACHE_OP_WEAK_REVALIDATE	BIT(11)
-- 
cgit v1.2.3


From 1b327b5ac57cf83e3d015de45d0142852f475375 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Fri, 10 Nov 2023 14:07:43 -0500
Subject: kill DCACHE_MAY_FREE

With the new ordering in __dentry_kill() it has become redundant -
it's set if and only if both DCACHE_DENTRY_KILLED and DCACHE_SHRINK_LIST
are set.

We set it in __dentry_kill(), after having set DCACHE_DENTRY_KILLED
with the only condition being that DCACHE_SHRINK_LIST is there;
all of that is done without dropping ->d_lock and the only place
that checks that flag (shrink_dentry_list()) does so under ->d_lock,
after having found the victim on its shrink list.  Since DCACHE_SHRINK_LIST
is set only when placing dentry into shrink list and removed only by
shrink_dentry_list() itself, a check for DCACHE_DENTRY_KILLED in
there would be equivalent to check for DCACHE_MAY_FREE.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 fs/dcache.c            | 6 ++----
 include/linux/dcache.h | 1 -
 2 files changed, 2 insertions(+), 5 deletions(-)

(limited to 'include')

diff --git a/fs/dcache.c b/fs/dcache.c
index 475ef1edba03..523cbf0780f0 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -614,10 +614,8 @@ static struct dentry *__dentry_kill(struct dentry *dentry)
 	}
 	spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
 	dentry_unlist(dentry);
-	if (dentry->d_flags & DCACHE_SHRINK_LIST) {
-		dentry->d_flags |= DCACHE_MAY_FREE;
+	if (dentry->d_flags & DCACHE_SHRINK_LIST)
 		can_free = false;
-	}
 	spin_unlock(&dentry->d_lock);
 	if (likely(can_free))
 		dentry_free(dentry);
@@ -1072,7 +1070,7 @@ void shrink_dentry_list(struct list_head *list)
 			bool can_free;
 			rcu_read_unlock();
 			d_shrink_del(dentry);
-			can_free = dentry->d_flags & DCACHE_MAY_FREE;
+			can_free = dentry->d_flags & DCACHE_DENTRY_KILLED;
 			spin_unlock(&dentry->d_lock);
 			if (can_free)
 				dentry_free(dentry);
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index b4449a1a47ff..48b393545ec2 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -202,7 +202,6 @@ struct dentry_operations {
 #define DCACHE_SPECIAL_TYPE		(5 << 20) /* Other file type */
 #define DCACHE_SYMLINK_TYPE		(6 << 20) /* Symlink */
 
-#define DCACHE_MAY_FREE			BIT(23)
 #define DCACHE_NOKEY_NAME		BIT(25) /* Encrypted name encoded without key */
 #define DCACHE_OP_REAL			BIT(26)
 
-- 
cgit v1.2.3


From 1b6ae9f6e6c3e3c35aad0f11b116a81780b8aa03 Mon Sep 17 00:00:00 2001
From: Vegard Nossum <vegard.nossum@oracle.com>
Date: Mon, 6 Nov 2023 14:44:17 +0100
Subject: dcache: remove unnecessary NULL check in dget_dlock()

dget_dlock() requires dentry->d_lock to be held when called, yet
contains a NULL check for dentry.

An audit of all calls to dget_dlock() shows that it is never called
with a NULL pointer (as spin_lock()/spin_unlock() would crash in these
cases):

  $ git grep -W '\<dget_dlock\>'

  arch/powerpc/platforms/cell/spufs/inode.c-              spin_lock(&dentry->d_lock);
  arch/powerpc/platforms/cell/spufs/inode.c-              if (simple_positive(dentry)) {
  arch/powerpc/platforms/cell/spufs/inode.c:                      dget_dlock(dentry);

  fs/autofs/expire.c-             spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
  fs/autofs/expire.c-             if (simple_positive(child)) {
  fs/autofs/expire.c:                     dget_dlock(child);

  fs/autofs/root.c:                       dget_dlock(active);
  fs/autofs/root.c-                       spin_unlock(&active->d_lock);

  fs/autofs/root.c:                       dget_dlock(expiring);
  fs/autofs/root.c-                       spin_unlock(&expiring->d_lock);

  fs/ceph/dir.c-          if (!spin_trylock(&dentry->d_lock))
  fs/ceph/dir.c-                  continue;
  [...]
  fs/ceph/dir.c:                          dget_dlock(dentry);

  fs/ceph/mds_client.c-           spin_lock(&alias->d_lock);
  [...]
  fs/ceph/mds_client.c:                   dn = dget_dlock(alias);

  fs/configfs/inode.c-            spin_lock(&dentry->d_lock);
  fs/configfs/inode.c-            if (simple_positive(dentry)) {
  fs/configfs/inode.c:                    dget_dlock(dentry);

  fs/libfs.c:                             found = dget_dlock(d);
  fs/libfs.c-                     spin_unlock(&d->d_lock);

  fs/libfs.c:             found = dget_dlock(child);
  fs/libfs.c-     spin_unlock(&child->d_lock);

  fs/libfs.c:                             child = dget_dlock(d);
  fs/libfs.c-                     spin_unlock(&d->d_lock);

  fs/ocfs2/dcache.c:                      dget_dlock(dentry);
  fs/ocfs2/dcache.c-                      spin_unlock(&dentry->d_lock);

  include/linux/dcache.h:static inline struct dentry *dget_dlock(struct dentry *dentry)

After taking out the NULL check, dget_dlock() becomes almost identical
to __dget_dlock(); the only difference is that dget_dlock() returns the
dentry that was passed in. These are static inline helpers, so we can
rely on the compiler to discard unused return values. We can therefore
also remove __dget_dlock() and replace calls to it by dget_dlock().

Also fix up and improve the kerneldoc comments while we're at it.

Al Viro pointed out that we can also clean up some of the callers to
make use of the returned value and provided a bit more info for the
kerneldoc.

While preparing v2 I also noticed that the tabs used in the kerneldoc
comments were causing the kerneldoc to get parsed incorrectly so I also
fixed this up (including for d_unhashed, which is otherwise unrelated).

Testing: x86 defconfig build + boot; make htmldocs for the kerneldoc
warning. objdump shows there are code generation changes.

Link: https://lore.kernel.org/all/20231022164520.915013-1-vegard.nossum@oracle.com/
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: linux-fsdevel@vger.kernel.org
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Waiman Long <Waiman.Long@hp.com>
Cc: linux-doc@vger.kernel.org
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 fs/dcache.c            | 16 ++++------------
 include/linux/dcache.h | 41 ++++++++++++++++++++++++++++++-----------
 2 files changed, 34 insertions(+), 23 deletions(-)

(limited to 'include')

diff --git a/fs/dcache.c b/fs/dcache.c
index 523cbf0780f0..bb18ea91d717 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -877,12 +877,6 @@ void dput_to_list(struct dentry *dentry, struct list_head *list)
 	spin_unlock(&dentry->d_lock);
 }
 
-/* This must be called with d_lock held */
-static inline void __dget_dlock(struct dentry *dentry)
-{
-	dentry->d_lockref.count++;
-}
-
 struct dentry *dget_parent(struct dentry *dentry)
 {
 	int gotref;
@@ -964,7 +958,7 @@ static struct dentry *__d_find_alias(struct inode *inode)
 	hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) {
 		spin_lock(&alias->d_lock);
  		if (!d_unhashed(alias)) {
-			__dget_dlock(alias);
+			dget_dlock(alias);
 			spin_unlock(&alias->d_lock);
 			return alias;
 		}
@@ -1569,8 +1563,7 @@ static enum d_walk_ret find_submount(void *_data, struct dentry *dentry)
 {
 	struct dentry **victim = _data;
 	if (d_mountpoint(dentry)) {
-		__dget_dlock(dentry);
-		*victim = dentry;
+		*victim = dget_dlock(dentry);
 		return D_WALK_QUIT;
 	}
 	return D_WALK_CONTINUE;
@@ -1715,8 +1708,7 @@ struct dentry *d_alloc(struct dentry * parent, const struct qstr *name)
 	 * don't need child lock because it is not subject
 	 * to concurrency here
 	 */
-	__dget_dlock(parent);
-	dentry->d_parent = parent;
+	dentry->d_parent = dget_dlock(parent);
 	hlist_add_head(&dentry->d_sib, &parent->d_children);
 	spin_unlock(&parent->d_lock);
 
@@ -2683,7 +2675,7 @@ struct dentry *d_exact_alias(struct dentry *entry, struct inode *inode)
 			spin_unlock(&alias->d_lock);
 			alias = NULL;
 		} else {
-			__dget_dlock(alias);
+			dget_dlock(alias);
 			__d_rehash(alias);
 			spin_unlock(&alias->d_lock);
 		}
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 48b393545ec2..1666c387861f 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -287,20 +287,40 @@ extern char *dentry_path(const struct dentry *, char *, int);
 /* Allocation counts.. */
 
 /**
- *	dget, dget_dlock -	get a reference to a dentry
- *	@dentry: dentry to get a reference to
+ * dget_dlock -	get a reference to a dentry
+ * @dentry: dentry to get a reference to
  *
- *	Given a dentry or %NULL pointer increment the reference count
- *	if appropriate and return the dentry. A dentry will not be 
- *	destroyed when it has references.
+ * Given a live dentry, increment the reference count and return the dentry.
+ * Caller must hold @dentry->d_lock.  Making sure that dentry is alive is
+ * caller's resonsibility.  There are many conditions sufficient to guarantee
+ * that; e.g. anything with non-negative refcount is alive, so's anything
+ * hashed, anything positive, anyone's parent, etc.
  */
 static inline struct dentry *dget_dlock(struct dentry *dentry)
 {
-	if (dentry)
-		dentry->d_lockref.count++;
+	dentry->d_lockref.count++;
 	return dentry;
 }
 
+
+/**
+ * dget - get a reference to a dentry
+ * @dentry: dentry to get a reference to
+ *
+ * Given a dentry or %NULL pointer increment the reference count
+ * if appropriate and return the dentry.  A dentry will not be
+ * destroyed when it has references.  Conversely, a dentry with
+ * no references can disappear for any number of reasons, starting
+ * with memory pressure.  In other words, that primitive is
+ * used to clone an existing reference; using it on something with
+ * zero refcount is a bug.
+ *
+ * NOTE: it will spin if @dentry->d_lock is held.  From the deadlock
+ * avoidance point of view it is equivalent to spin_lock()/increment
+ * refcount/spin_unlock(), so calling it under @dentry->d_lock is
+ * always a bug; so's calling it under ->d_lock on any of its descendents.
+ *
+ */
 static inline struct dentry *dget(struct dentry *dentry)
 {
 	if (dentry)
@@ -311,12 +331,11 @@ static inline struct dentry *dget(struct dentry *dentry)
 extern struct dentry *dget_parent(struct dentry *dentry);
 
 /**
- *	d_unhashed -	is dentry hashed
- *	@dentry: entry to check
+ * d_unhashed - is dentry hashed
+ * @dentry: entry to check
  *
- *	Returns true if the dentry passed is not currently hashed.
+ * Returns true if the dentry passed is not currently hashed.
  */
- 
 static inline int d_unhashed(const struct dentry *dentry)
 {
 	return hlist_bl_unhashed(&dentry->d_hash);
-- 
cgit v1.2.3