fs: make the i_state flags an enum

josefbacik · brauner · commit 9a98f9e84cfb · 2025-08-29T15:00:30.000+02:00
Adjusting i_state flags always means updating the values manually. Bring these forward into the 2020's and make a nice clean macro for defining the i_state values as an enum, providing __ variants for the cases where we need the bit position instead of the actual value, and leaving the actual NAME as the 1U << bit value. Reviewed-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Link: https://lore.kernel.org/0da9348da6ece0dce12fccec07b1dd2b8e4cfdab.1756222464.git.josef@toxicpanda.com Signed-off-by: Christian Brauner <brauner@kernel.org>
diff --git a/include/linux/fs.h b/include/linux/fs.h
@@ -664,6 +664,124 @@ is_uncached_acl(struct posix_acl *acl)
 #define IOP_MGTIME	0x0020
 #define IOP_CACHED_LINK	0x0040
 
+/*
+ * Inode state bits.  Protected by inode->i_lock
+ *
+ * Four bits determine the dirty state of the inode: I_DIRTY_SYNC,
+ * I_DIRTY_DATASYNC, I_DIRTY_PAGES, and I_DIRTY_TIME.
+ *
+ * Four bits define the lifetime of an inode.  Initially, inodes are I_NEW,
+ * until that flag is cleared.  I_WILL_FREE, I_FREEING and I_CLEAR are set at
+ * various stages of removing an inode.
+ *
+ * Two bits are used for locking and completion notification, I_NEW and I_SYNC.
+ *
+ * I_DIRTY_SYNC		Inode is dirty, but doesn't have to be written on
+ *			fdatasync() (unless I_DIRTY_DATASYNC is also set).
+ *			Timestamp updates are the usual cause.
+ * I_DIRTY_DATASYNC	Data-related inode changes pending.  We keep track of
+ *			these changes separately from I_DIRTY_SYNC so that we
+ *			don't have to write inode on fdatasync() when only
+ *			e.g. the timestamps have changed.
+ * I_DIRTY_PAGES	Inode has dirty pages.  Inode itself may be clean.
+ * I_DIRTY_TIME		The inode itself has dirty timestamps, and the
+ *			lazytime mount option is enabled.  We keep track of this
+ *			separately from I_DIRTY_SYNC in order to implement
+ *			lazytime.  This gets cleared if I_DIRTY_INODE
+ *			(I_DIRTY_SYNC and/or I_DIRTY_DATASYNC) gets set. But
+ *			I_DIRTY_TIME can still be set if I_DIRTY_SYNC is already
+ *			in place because writeback might already be in progress
+ *			and we don't want to lose the time update
+ * I_NEW		Serves as both a mutex and completion notification.
+ *			New inodes set I_NEW.  If two processes both create
+ *			the same inode, one of them will release its inode and
+ *			wait for I_NEW to be released before returning.
+ *			Inodes in I_WILL_FREE, I_FREEING or I_CLEAR state can
+ *			also cause waiting on I_NEW, without I_NEW actually
+ *			being set.  find_inode() uses this to prevent returning
+ *			nearly-dead inodes.
+ * I_WILL_FREE		Must be set when calling write_inode_now() if i_count
+ *			is zero.  I_FREEING must be set when I_WILL_FREE is
+ *			cleared.
+ * I_FREEING		Set when inode is about to be freed but still has dirty
+ *			pages or buffers attached or the inode itself is still
+ *			dirty.
+ * I_CLEAR		Added by clear_inode().  In this state the inode is
+ *			clean and can be destroyed.  Inode keeps I_FREEING.
+ *
+ *			Inodes that are I_WILL_FREE, I_FREEING or I_CLEAR are
+ *			prohibited for many purposes.  iget() must wait for
+ *			the inode to be completely released, then create it
+ *			anew.  Other functions will just ignore such inodes,
+ *			if appropriate.  I_NEW is used for waiting.
+ *
+ * I_SYNC		Writeback of inode is running. The bit is set during
+ *			data writeback, and cleared with a wakeup on the bit
+ *			address once it is done. The bit is also used to pin
+ *			the inode in memory for flusher thread.
+ *
+ * I_REFERENCED		Marks the inode as recently references on the LRU list.
+ *
+ * I_WB_SWITCH		Cgroup bdi_writeback switching in progress.  Used to
+ *			synchronize competing switching instances and to tell
+ *			wb stat updates to grab the i_pages lock.  See
+ *			inode_switch_wbs_work_fn() for details.
+ *
+ * I_OVL_INUSE		Used by overlayfs to get exclusive ownership on upper
+ *			and work dirs among overlayfs mounts.
+ *
+ * I_CREATING		New object's inode in the middle of setting up.
+ *
+ * I_DONTCACHE		Evict inode as soon as it is not used anymore.
+ *
+ * I_SYNC_QUEUED	Inode is queued in b_io or b_more_io writeback lists.
+ *			Used to detect that mark_inode_dirty() should not move
+ *			inode between dirty lists.
+ *
+ * I_PINNING_FSCACHE_WB	Inode is pinning an fscache object for writeback.
+ *
+ * I_LRU_ISOLATING	Inode is pinned being isolated from LRU without holding
+ *			i_count.
+ *
+ * Q: What is the difference between I_WILL_FREE and I_FREEING?
+ *
+ * __I_{SYNC,NEW,LRU_ISOLATING} are used to derive unique addresses to wait
+ * upon. There's one free address left.
+ */
+
+enum inode_state_bits {
+	__I_NEW			= 0U,
+	__I_SYNC		= 1U,
+	__I_LRU_ISOLATING	= 2U
+	/* reserved wait address bit 3 */
+};
+
+enum inode_state_flags_t {
+	I_NEW			= (1U << __I_NEW),
+	I_SYNC			= (1U << __I_SYNC),
+	I_LRU_ISOLATING         = (1U << __I_LRU_ISOLATING),
+	/* reserved flag bit 3 */
+	I_DIRTY_SYNC		= (1U << 4),
+	I_DIRTY_DATASYNC	= (1U << 5),
+	I_DIRTY_PAGES		= (1U << 6),
+	I_WILL_FREE		= (1U << 7),
+	I_FREEING		= (1U << 8),
+	I_CLEAR			= (1U << 9),
+	I_REFERENCED		= (1U << 10),
+	I_LINKABLE		= (1U << 11),
+	I_DIRTY_TIME		= (1U << 12),
+	I_WB_SWITCH		= (1U << 13),
+	I_OVL_INUSE		= (1U << 14),
+	I_CREATING		= (1U << 15),
+	I_DONTCACHE		= (1U << 16),
+	I_SYNC_QUEUED		= (1U << 17),
+	I_PINNING_NETFS_WB	= (1U << 18)
+};
+
+#define I_DIRTY_INODE (I_DIRTY_SYNC | I_DIRTY_DATASYNC)
+#define I_DIRTY (I_DIRTY_INODE | I_DIRTY_PAGES)
+#define I_DIRTY_ALL (I_DIRTY | I_DIRTY_TIME)
+
 /*
  * Keep mostly read-only and often accessed (especially for
  * the RCU path lookup and 'stat' data) fields at the beginning
@@ -722,7 +840,7 @@ struct inode {
 #endif
 
 	/* Misc */
-	u32			i_state;
+	enum inode_state_flags_t	i_state;
 	/* 32-bit hole */
 	struct rw_semaphore	i_rwsem;
 
@@ -2482,117 +2600,6 @@ static inline void kiocb_clone(struct kiocb *kiocb, struct kiocb *kiocb_src,
 	};
 }
 
-/*
- * Inode state bits.  Protected by inode->i_lock
- *
- * Four bits determine the dirty state of the inode: I_DIRTY_SYNC,
- * I_DIRTY_DATASYNC, I_DIRTY_PAGES, and I_DIRTY_TIME.
- *
- * Four bits define the lifetime of an inode.  Initially, inodes are I_NEW,
- * until that flag is cleared.  I_WILL_FREE, I_FREEING and I_CLEAR are set at
- * various stages of removing an inode.
- *
- * Two bits are used for locking and completion notification, I_NEW and I_SYNC.
- *
- * I_DIRTY_SYNC		Inode is dirty, but doesn't have to be written on
- *			fdatasync() (unless I_DIRTY_DATASYNC is also set).
- *			Timestamp updates are the usual cause.
- * I_DIRTY_DATASYNC	Data-related inode changes pending.  We keep track of
- *			these changes separately from I_DIRTY_SYNC so that we
- *			don't have to write inode on fdatasync() when only
- *			e.g. the timestamps have changed.
- * I_DIRTY_PAGES	Inode has dirty pages.  Inode itself may be clean.
- * I_DIRTY_TIME		The inode itself has dirty timestamps, and the
- *			lazytime mount option is enabled.  We keep track of this
- *			separately from I_DIRTY_SYNC in order to implement
- *			lazytime.  This gets cleared if I_DIRTY_INODE
- *			(I_DIRTY_SYNC and/or I_DIRTY_DATASYNC) gets set. But
- *			I_DIRTY_TIME can still be set if I_DIRTY_SYNC is already
- *			in place because writeback might already be in progress
- *			and we don't want to lose the time update
- * I_NEW		Serves as both a mutex and completion notification.
- *			New inodes set I_NEW.  If two processes both create
- *			the same inode, one of them will release its inode and
- *			wait for I_NEW to be released before returning.
- *			Inodes in I_WILL_FREE, I_FREEING or I_CLEAR state can
- *			also cause waiting on I_NEW, without I_NEW actually
- *			being set.  find_inode() uses this to prevent returning
- *			nearly-dead inodes.
- * I_WILL_FREE		Must be set when calling write_inode_now() if i_count
- *			is zero.  I_FREEING must be set when I_WILL_FREE is
- *			cleared.
- * I_FREEING		Set when inode is about to be freed but still has dirty
- *			pages or buffers attached or the inode itself is still
- *			dirty.
- * I_CLEAR		Added by clear_inode().  In this state the inode is
- *			clean and can be destroyed.  Inode keeps I_FREEING.
- *
- *			Inodes that are I_WILL_FREE, I_FREEING or I_CLEAR are
- *			prohibited for many purposes.  iget() must wait for
- *			the inode to be completely released, then create it
- *			anew.  Other functions will just ignore such inodes,
- *			if appropriate.  I_NEW is used for waiting.
- *
- * I_SYNC		Writeback of inode is running. The bit is set during
- *			data writeback, and cleared with a wakeup on the bit
- *			address once it is done. The bit is also used to pin
- *			the inode in memory for flusher thread.
- *
- * I_REFERENCED		Marks the inode as recently references on the LRU list.
- *
- * I_WB_SWITCH		Cgroup bdi_writeback switching in progress.  Used to
- *			synchronize competing switching instances and to tell
- *			wb stat updates to grab the i_pages lock.  See
- *			inode_switch_wbs_work_fn() for details.
- *
- * I_OVL_INUSE		Used by overlayfs to get exclusive ownership on upper
- *			and work dirs among overlayfs mounts.
- *
- * I_CREATING		New object's inode in the middle of setting up.
- *
- * I_DONTCACHE		Evict inode as soon as it is not used anymore.
- *
- * I_SYNC_QUEUED	Inode is queued in b_io or b_more_io writeback lists.
- *			Used to detect that mark_inode_dirty() should not move
- * 			inode between dirty lists.
- *
- * I_PINNING_FSCACHE_WB	Inode is pinning an fscache object for writeback.
- *
- * I_LRU_ISOLATING	Inode is pinned being isolated from LRU without holding
- *			i_count.
- *
- * Q: What is the difference between I_WILL_FREE and I_FREEING?
- *
- * __I_{SYNC,NEW,LRU_ISOLATING} are used to derive unique addresses to wait
- * upon. There's one free address left.
- */
-#define __I_NEW			0
-#define I_NEW			(1 << __I_NEW)
-#define __I_SYNC		1
-#define I_SYNC			(1 << __I_SYNC)
-#define __I_LRU_ISOLATING	2
-#define I_LRU_ISOLATING		(1 << __I_LRU_ISOLATING)
-
-#define I_DIRTY_SYNC		(1 << 3)
-#define I_DIRTY_DATASYNC	(1 << 4)
-#define I_DIRTY_PAGES		(1 << 5)
-#define I_WILL_FREE		(1 << 6)
-#define I_FREEING		(1 << 7)
-#define I_CLEAR			(1 << 8)
-#define I_REFERENCED		(1 << 9)
-#define I_LINKABLE		(1 << 10)
-#define I_DIRTY_TIME		(1 << 11)
-#define I_WB_SWITCH		(1 << 12)
-#define I_OVL_INUSE		(1 << 13)
-#define I_CREATING		(1 << 14)
-#define I_DONTCACHE		(1 << 15)
-#define I_SYNC_QUEUED		(1 << 16)
-#define I_PINNING_NETFS_WB	(1 << 17)
-
-#define I_DIRTY_INODE (I_DIRTY_SYNC | I_DIRTY_DATASYNC)
-#define I_DIRTY (I_DIRTY_INODE | I_DIRTY_PAGES)
-#define I_DIRTY_ALL (I_DIRTY | I_DIRTY_TIME)
-
 extern void __mark_inode_dirty(struct inode *, int);
 static inline void mark_inode_dirty(struct inode *inode)
 {
