3 files changed, 99 insertions, 18 deletions

diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 3e64f14739dd..0c8342747cab 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -277,10 +277,11 @@ unlocked_inode_to_wb_begin(struct inode *inode, struct wb_lock_cookie *cookie)
 	rcu_read_lock();
 
 	/*
-	 * Paired with store_release in inode_switch_wbs_work_fn() and
+	 * Paired with a release fence in inode_do_switch_wbs() and
 	 * ensures that we see the new wb if we see cleared I_WB_SWITCH.
 	 */
-	cookie->locked = smp_load_acquire(&inode->i_state) & I_WB_SWITCH;
+	cookie->locked = inode_state_read_once(inode) & I_WB_SWITCH;
+	smp_rmb();
 
 	if (unlikely(cookie->locked))
 		xa_lock_irqsave(&inode->i_mapping->i_pages, cookie->flags);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index ac62b9d10b00..21c73df3ce75 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -759,7 +759,7 @@ enum inode_state_bits {
 	/* reserved wait address bit 3 */
 };
 
-enum inode_state_flags_t {
+enum inode_state_flags_enum {
 	I_NEW			= (1U << __I_NEW),
 	I_SYNC			= (1U << __I_SYNC),
 	I_LRU_ISOLATING         = (1U << __I_LRU_ISOLATING),
@@ -786,6 +786,13 @@ enum inode_state_flags_t {
 #define I_DIRTY_ALL (I_DIRTY | I_DIRTY_TIME)
 
 /*
+ * Use inode_state_read() & friends to access.
+ */
+struct inode_state_flags {
+	enum inode_state_flags_enum __state;
+};
+
+/*
  * Keep mostly read-only and often accessed (especially for
  * the RCU path lookup and 'stat' data) fields at the beginning
  * of the 'struct inode'
@@ -843,7 +850,7 @@ struct inode {
 #endif
 
 	/* Misc */
-	enum inode_state_flags_t	i_state;
+	struct inode_state_flags i_state;
 	/* 32-bit hole */
 	struct rw_semaphore	i_rwsem;
 
@@ -902,6 +909,80 @@ struct inode {
 	void			*i_private; /* fs or device private pointer */
 } __randomize_layout;
 
+/*
+ * i_state handling
+ *
+ * We hide all of it behind helpers so that we can validate consumers.
+ */
+static inline enum inode_state_flags_enum inode_state_read_once(struct inode *inode)
+{
+	return READ_ONCE(inode->i_state.__state);
+}
+
+static inline enum inode_state_flags_enum inode_state_read(struct inode *inode)
+{
+	lockdep_assert_held(&inode->i_lock);
+	return inode->i_state.__state;
+}
+
+static inline void inode_state_set_raw(struct inode *inode,
+				       enum inode_state_flags_enum flags)
+{
+	WRITE_ONCE(inode->i_state.__state, inode->i_state.__state | flags);
+}
+
+static inline void inode_state_set(struct inode *inode,
+				   enum inode_state_flags_enum flags)
+{
+	lockdep_assert_held(&inode->i_lock);
+	inode_state_set_raw(inode, flags);
+}
+
+static inline void inode_state_clear_raw(struct inode *inode,
+					 enum inode_state_flags_enum flags)
+{
+	WRITE_ONCE(inode->i_state.__state, inode->i_state.__state & ~flags);
+}
+
+static inline void inode_state_clear(struct inode *inode,
+				     enum inode_state_flags_enum flags)
+{
+	lockdep_assert_held(&inode->i_lock);
+	inode_state_clear_raw(inode, flags);
+}
+
+static inline void inode_state_assign_raw(struct inode *inode,
+					  enum inode_state_flags_enum flags)
+{
+	WRITE_ONCE(inode->i_state.__state, flags);
+}
+
+static inline void inode_state_assign(struct inode *inode,
+				      enum inode_state_flags_enum flags)
+{
+	lockdep_assert_held(&inode->i_lock);
+	inode_state_assign_raw(inode, flags);
+}
+
+static inline void inode_state_replace_raw(struct inode *inode,
+					   enum inode_state_flags_enum clearflags,
+					   enum inode_state_flags_enum setflags)
+{
+	enum inode_state_flags_enum flags;
+	flags = inode->i_state.__state;
+	flags &= ~clearflags;
+	flags |= setflags;
+	inode_state_assign_raw(inode, flags);
+}
+
+static inline void inode_state_replace(struct inode *inode,
+				       enum inode_state_flags_enum clearflags,
+				       enum inode_state_flags_enum setflags)
+{
+	lockdep_assert_held(&inode->i_lock);
+	inode_state_replace_raw(inode, clearflags, setflags);
+}
+
 static inline void inode_set_cached_link(struct inode *inode, char *link, int linklen)
 {
 	VFS_WARN_ON_INODE(strlen(link) != linklen, inode);
@@ -949,6 +1030,16 @@ static inline void inode_fake_hash(struct inode *inode)
 	hlist_add_fake(&inode->i_hash);
 }
 
+static inline void wait_on_inode(struct inode *inode)
+{
+	wait_var_event(inode_state_wait_address(inode, __I_NEW),
+		       !(inode_state_read_once(inode) & I_NEW));
+	/*
+	 * Pairs with routines clearing I_NEW.
+	 */
+	smp_rmb();
+}
+
 /*
  * inode->i_rwsem nesting subclasses for the lock validator:
  *
@@ -2635,8 +2726,8 @@ static inline int icount_read(const struct inode *inode)
  */
 static inline bool inode_is_dirtytime_only(struct inode *inode)
 {
-	return (inode->i_state & (I_DIRTY_TIME | I_NEW |
-				  I_FREEING | I_WILL_FREE)) == I_DIRTY_TIME;
+	return (inode_state_read_once(inode) &
+	       (I_DIRTY_TIME | I_NEW | I_FREEING | I_WILL_FREE)) == I_DIRTY_TIME;
 }
 
 extern void inc_nlink(struct inode *inode);
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index e1e1231a6830..102071ffedcb 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -189,17 +189,6 @@ void wakeup_flusher_threads_bdi(struct backing_dev_info *bdi,
 void inode_wait_for_writeback(struct inode *inode);
 void inode_io_list_del(struct inode *inode);
 
-/* writeback.h requires fs.h; it, too, is not included from here. */
-static inline void wait_on_inode(struct inode *inode)
-{
-	wait_var_event(inode_state_wait_address(inode, __I_NEW),
-		       !(READ_ONCE(inode->i_state) & I_NEW));
-	/*
-	 * Pairs with routines clearing I_NEW.
-	 */
-	smp_rmb();
-}
-
 #ifdef CONFIG_CGROUP_WRITEBACK
 
 #include <linux/cgroup.h>
@@ -238,7 +227,7 @@ static inline void inode_attach_wb(struct inode *inode, struct folio *folio)
 static inline void inode_detach_wb(struct inode *inode)
 {
 	if (inode->i_wb) {
-		WARN_ON_ONCE(!(inode->i_state & I_CLEAR));
+		WARN_ON_ONCE(!(inode_state_read_once(inode) & I_CLEAR));
 		wb_put(inode->i_wb);
 		inode->i_wb = NULL;
 	}