headers/deps: fs: Introduce <linux/fs_api_dio.h> for Direct IO related APIs

<linux/fs_api.h> is used in over 4,100 files, while the Direct IO
related functions are only used by ~47 files.

So move them over into their new <linux/fs_api_dio.h> header.

The motivation is to allow the reduction of <linux/fs_api.h>
header dependencies.

Note: we also move inode_drain_writes(), which uses inode_dio_wait().
It's only used by mm/swapfile.c.

Signed-off-by: Ingo Molnar <mingo@kernel.org>

2 files changed, 78 insertions, 71 deletions

diff --git a/include/linux/fs_api.h b/include/linux/fs_api.h
index b2d51c13fd15b7..f4cfa09f13c310 100644
--- a/include/linux/fs_api.h
+++ b/include/linux/fs_api.h
@@ -1501,66 +1501,6 @@ extern int generic_file_open(struct inode * inode, struct file * filp);
 extern int nonseekable_open(struct inode * inode, struct file * filp);
 extern int stream_open(struct inode * inode, struct file * filp);
 
-#ifdef CONFIG_BLOCK
-typedef void (dio_submit_t)(struct bio *bio, struct inode *inode,
-			    loff_t file_offset);
-
-enum {
-	/* need locking between buffered and direct access */
-	DIO_LOCKING	= 0x01,
-
-	/* filesystem does not support filling holes */
-	DIO_SKIP_HOLES	= 0x02,
-};
-
-ssize_t __blockdev_direct_IO(struct kiocb *iocb, struct inode *inode,
-			     struct block_device *bdev, struct iov_iter *iter,
-			     get_block_t get_block,
-			     dio_iodone_t end_io, dio_submit_t submit_io,
-			     int flags);
-
-static inline ssize_t blockdev_direct_IO(struct kiocb *iocb,
-					 struct inode *inode,
-					 struct iov_iter *iter,
-					 get_block_t get_block)
-{
-	return __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev, iter,
-			get_block, NULL, NULL, DIO_LOCKING | DIO_SKIP_HOLES);
-}
-#endif
-
-void inode_dio_wait(struct inode *inode);
-
-/**
- * inode_dio_begin - signal start of a direct I/O requests
- * @inode: inode the direct I/O happens on
- *
- * This is called once we've finished processing a direct I/O request,
- * and is used to wake up callers waiting for direct I/O to be quiesced.
- */
-static inline void inode_dio_begin(struct inode *inode)
-{
-	atomic_inc(&inode->i_dio_count);
-}
-
-/**
- * inode_dio_end - signal finish of a direct I/O requests
- * @inode: inode the direct I/O happens on
- *
- * This is called once we've finished processing a direct I/O request,
- * and is used to wake up callers waiting for direct I/O to be quiesced.
- */
-static inline void inode_dio_end(struct inode *inode)
-{
-	if (atomic_dec_and_test(&inode->i_dio_count))
-		wake_up_bit(&inode->i_state, __I_DIO_WAKEUP);
-}
-
-/*
- * Warn about a page cache invalidation failure diring a direct I/O write.
- */
-void dio_warn_stale_pagecache(struct file *filp);
-
 extern void inode_set_flags(struct inode *inode, unsigned int flags,
 			    unsigned int mask);
 
@@ -1871,14 +1811,4 @@ extern int vfs_fadvise(struct file *file, loff_t offset, loff_t len,
 extern int generic_fadvise(struct file *file, loff_t offset, loff_t len,
 			   int advice);
 
-/*
- * Flush file data before changing attributes.  Caller must hold any locks
- * required to prevent further writes to this file until we're done setting
- * flags.
- */
-static inline int inode_drain_writes(struct inode *inode)
-{
-	inode_dio_wait(inode);
-	return filemap_write_and_wait(inode->i_mapping);
-}
 #endif /* _LINUX_FS_API_H */
diff --git a/include/linux/fs_api_dio.h b/include/linux/fs_api_dio.h
index 83be38d6d4132c..b5e24c723516cd 100644
--- a/include/linux/fs_api_dio.h
+++ b/include/linux/fs_api_dio.h
@@ -1 +1,78 @@
-#include <linux/fs.h>
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_FS_API_DIO_H
+#define _LINUX_FS_API_DIO_H
+
+#include <linux/fs_api.h>
+
+#ifdef CONFIG_BLOCK
+typedef void (dio_submit_t)(struct bio *bio, struct inode *inode,
+			    loff_t file_offset);
+
+enum {
+	/* need locking between buffered and direct access */
+	DIO_LOCKING	= 0x01,
+
+	/* filesystem does not support filling holes */
+	DIO_SKIP_HOLES	= 0x02,
+};
+
+ssize_t __blockdev_direct_IO(struct kiocb *iocb, struct inode *inode,
+			     struct block_device *bdev, struct iov_iter *iter,
+			     get_block_t get_block,
+			     dio_iodone_t end_io, dio_submit_t submit_io,
+			     int flags);
+
+static inline ssize_t blockdev_direct_IO(struct kiocb *iocb,
+					 struct inode *inode,
+					 struct iov_iter *iter,
+					 get_block_t get_block)
+{
+	return __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev, iter,
+			get_block, NULL, NULL, DIO_LOCKING | DIO_SKIP_HOLES);
+}
+#endif
+
+void inode_dio_wait(struct inode *inode);
+
+/**
+ * inode_dio_begin - signal start of a direct I/O requests
+ * @inode: inode the direct I/O happens on
+ *
+ * This is called once we've finished processing a direct I/O request,
+ * and is used to wake up callers waiting for direct I/O to be quiesced.
+ */
+static inline void inode_dio_begin(struct inode *inode)
+{
+	atomic_inc(&inode->i_dio_count);
+}
+
+/**
+ * inode_dio_end - signal finish of a direct I/O requests
+ * @inode: inode the direct I/O happens on
+ *
+ * This is called once we've finished processing a direct I/O request,
+ * and is used to wake up callers waiting for direct I/O to be quiesced.
+ */
+static inline void inode_dio_end(struct inode *inode)
+{
+	if (atomic_dec_and_test(&inode->i_dio_count))
+		wake_up_bit(&inode->i_state, __I_DIO_WAKEUP);
+}
+
+/*
+ * Warn about a page cache invalidation failure diring a direct I/O write.
+ */
+void dio_warn_stale_pagecache(struct file *filp);
+
+/*
+ * Flush file data before changing attributes.  Caller must hold any locks
+ * required to prevent further writes to this file until we're done setting
+ * flags.
+ */
+static inline int inode_drain_writes(struct inode *inode)
+{
+	inode_dio_wait(inode);
+	return filemap_write_and_wait(inode->i_mapping);
+}
+
+#endif /* _LINUX_FS_API_DIO_H */