1 files changed, 42 insertions, 5 deletions

diff --git a/fs/dcache.c b/fs/dcache.c
index 4c144519aa70..8bdc278a0205 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -35,6 +35,8 @@
 #include "internal.h"
 #include "mount.h"
 
+#include <asm/runtime-const.h>
+
 /*
  * Usage:
  * dcache->d_inode->i_lock protects:
@@ -100,9 +102,10 @@ static unsigned int d_hash_shift __ro_after_init;
 
 static struct hlist_bl_head *dentry_hashtable __ro_after_init;
 
-static inline struct hlist_bl_head *d_hash(unsigned int hash)
+static inline struct hlist_bl_head *d_hash(unsigned long hashlen)
 {
-	return dentry_hashtable + (hash >> d_hash_shift);
+	return runtime_const_ptr(dentry_hashtable) +
+		runtime_const_shift_right_32(hashlen, d_hash_shift);
 }
 
 #define IN_LOOKUP_SHIFT 10
@@ -1552,7 +1555,7 @@ void shrink_dcache_for_umount(struct super_block *sb)
 {
 	struct dentry *dentry;
 
-	WARN(down_read_trylock(&sb->s_umount), "s_umount should've been locked");
+	rwsem_assert_held_write(&sb->s_umount);
 
 	dentry = sb->s_root;
 	sb->s_root = NULL;
@@ -2110,7 +2113,7 @@ static noinline struct dentry *__d_lookup_rcu_op_compare(
 	unsigned *seqp)
 {
 	u64 hashlen = name->hash_len;
-	struct hlist_bl_head *b = d_hash(hashlen_hash(hashlen));
+	struct hlist_bl_head *b = d_hash(hashlen);
 	struct hlist_bl_node *node;
 	struct dentry *dentry;
 
@@ -2177,7 +2180,7 @@ struct dentry *__d_lookup_rcu(const struct dentry *parent,
 {
 	u64 hashlen = name->hash_len;
 	const unsigned char *str = name->name;
-	struct hlist_bl_head *b = d_hash(hashlen_hash(hashlen));
+	struct hlist_bl_head *b = d_hash(hashlen);
 	struct hlist_bl_node *node;
 	struct dentry *dentry;
 
@@ -3103,6 +3106,34 @@ void d_tmpfile(struct file *file, struct inode *inode)
 }
 EXPORT_SYMBOL(d_tmpfile);
 
+/*
+ * Obtain inode number of the parent dentry.
+ */
+ino_t d_parent_ino(struct dentry *dentry)
+{
+	struct dentry *parent;
+	struct inode *iparent;
+	unsigned seq;
+	ino_t ret;
+
+	scoped_guard(rcu) {
+		seq = raw_seqcount_begin(&dentry->d_seq);
+		parent = READ_ONCE(dentry->d_parent);
+		iparent = d_inode_rcu(parent);
+		if (likely(iparent)) {
+			ret = iparent->i_ino;
+			if (!read_seqcount_retry(&dentry->d_seq, seq))
+				return ret;
+		}
+	}
+
+	spin_lock(&dentry->d_lock);
+	ret = dentry->d_parent->d_inode->i_ino;
+	spin_unlock(&dentry->d_lock);
+	return ret;
+}
+EXPORT_SYMBOL(d_parent_ino);
+
 static __initdata unsigned long dhash_entries;
 static int __init set_dhash_entries(char *str)
 {
@@ -3132,6 +3163,9 @@ static void __init dcache_init_early(void)
 					0,
 					0);
 	d_hash_shift = 32 - d_hash_shift;
+
+	runtime_const_init(shift, d_hash_shift);
+	runtime_const_init(ptr, dentry_hashtable);
 }
 
 static void __init dcache_init(void)
@@ -3160,6 +3194,9 @@ static void __init dcache_init(void)
 					0,
 					0);
 	d_hash_shift = 32 - d_hash_shift;
+
+	runtime_const_init(shift, d_hash_shift);
+	runtime_const_init(ptr, dentry_hashtable);
 }
 
 /* SLAB cache for __getname() consumers */