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

@@ -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;

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)