fs: rename i_ctime field to __i_ctime

Now that everything in-tree is converted to use the accessor functions,
rename the i_ctime field in the inode to discourage direct access.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Message-Id: <20230705185812.579118-4-jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

include/linux/fs.h

@@ -642,7 +642,7 @@ struct inode {
 	loff_t			i_size;
 	struct timespec64	i_atime;
 	struct timespec64	i_mtime;
-	struct timespec64	i_ctime;
+	struct timespec64	__i_ctime; /* use inode_*_ctime accessors! */
 	spinlock_t		i_lock;	/* i_blocks, i_bytes, maybe i_size */
 	unsigned short          i_bytes;
 	u8			i_blkbits;
@@ -1485,7 +1485,7 @@ struct timespec64 inode_set_ctime_current(struct inode *inode);
  */
 static inline struct timespec64 inode_get_ctime(const struct inode *inode)
 {
-	return inode->i_ctime;
+	return inode->__i_ctime;
 }
 
 /**
@@ -1498,7 +1498,7 @@ static inline struct timespec64 inode_get_ctime(const struct inode *inode)
 static inline struct timespec64 inode_set_ctime_to_ts(struct inode *inode,
 						      struct timespec64 ts)
 {
-	inode->i_ctime = ts;
+	inode->__i_ctime = ts;
 	return ts;
 }