[PATCH v3 01/14] fs: Move enum rw_hint into a new header file

[Bart Van Assche <bvanassche@acm.org>]

Move enum rw_hint into a new header file to prepare for using this data
type in the block layer. Add the attribute __packed to reduce the space
occupied by instances of this data type from four bytes to one byte.
Change the data type of i_write_hint from u8 into enum rw_hint. Change
the RWH_* constants into literal constants to prevent that
<uapi/linux/fcntl.h> would have to be included.

Cc: Jan Kara <jack@suse.cz>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Christian Brauner <brauner@kernel.org>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 fs/f2fs/f2fs.h          |  1 +
 fs/fcntl.c              |  1 +
 fs/inode.c              |  1 +
 include/linux/fs.h      | 16 ++--------------
 include/linux/rw_hint.h | 20 ++++++++++++++++++++
 5 files changed, 25 insertions(+), 14 deletions(-)
 create mode 100644 include/linux/rw_hint.h

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 6d688e42d89c..56ee7fff55c7 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -24,6 +24,7 @@
 #include <linux/blkdev.h>
 #include <linux/quotaops.h>
 #include <linux/part_stat.h>
+#include <linux/rw_hint.h>
 #include <crypto/hash.h>
 
 #include <linux/fscrypt.h>
diff --git a/fs/fcntl.c b/fs/fcntl.c
index e871009f6c88..ed923640aecf 100644
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -27,6 +27,7 @@
 #include <linux/memfd.h>
 #include <linux/compat.h>
 #include <linux/mount.h>
+#include <linux/rw_hint.h>
 
 #include <linux/poll.h>
 #include <asm/siginfo.h>
diff --git a/fs/inode.c b/fs/inode.c
index 84bc3c76e5cc..ebcc41ac9682 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -20,6 +20,7 @@
 #include <linux/ratelimit.h>
 #include <linux/list_lru.h>
 #include <linux/iversion.h>
+#include <linux/rw_hint.h>
 #include <trace/events/writeback.h>
 #include "internal.h"
 
diff --git a/include/linux/fs.h b/include/linux/fs.h
index b528f063e8ff..971f0bafa782 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -43,6 +43,7 @@
 #include <linux/cred.h>
 #include <linux/mnt_idmapping.h>
 #include <linux/slab.h>
+#include <linux/rw_hint.h>
 
 #include <asm/byteorder.h>
 #include <uapi/linux/fs.h>
@@ -309,19 +310,6 @@ struct address_space;
 struct writeback_control;
 struct readahead_control;
 
-/*
- * Write life time hint values.
- * Stored in struct inode as u8.
- */
-enum rw_hint {
-	WRITE_LIFE_NOT_SET	= 0,
-	WRITE_LIFE_NONE		= RWH_WRITE_LIFE_NONE,
-	WRITE_LIFE_SHORT	= RWH_WRITE_LIFE_SHORT,
-	WRITE_LIFE_MEDIUM	= RWH_WRITE_LIFE_MEDIUM,
-	WRITE_LIFE_LONG		= RWH_WRITE_LIFE_LONG,
-	WRITE_LIFE_EXTREME	= RWH_WRITE_LIFE_EXTREME,
-};
-
 /* Match RWF_* bits to IOCB bits */
 #define IOCB_HIPRI		(__force int) RWF_HIPRI
 #define IOCB_DSYNC		(__force int) RWF_DSYNC
@@ -677,7 +665,7 @@ struct inode {
 	spinlock_t		i_lock;	/* i_blocks, i_bytes, maybe i_size */
 	unsigned short          i_bytes;
 	u8			i_blkbits;
-	u8			i_write_hint;
+	enum rw_hint		i_write_hint;
 	blkcnt_t		i_blocks;
 
 #ifdef __NEED_I_SIZE_ORDERED
diff --git a/include/linux/rw_hint.h b/include/linux/rw_hint.h
new file mode 100644
index 000000000000..4a7d28945973
--- /dev/null
+++ b/include/linux/rw_hint.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_RW_HINT_H
+#define _LINUX_RW_HINT_H
+
+#include <linux/build_bug.h>
+#include <linux/compiler_attributes.h>
+
+/* Block storage write lifetime hint values. */
+enum rw_hint {
+	WRITE_LIFE_NOT_SET	= 0, /* RWH_WRITE_LIFE_NOT_SET */
+	WRITE_LIFE_NONE		= 1, /* RWH_WRITE_LIFE_NONE */
+	WRITE_LIFE_SHORT	= 2, /* RWH_WRITE_LIFE_SHORT */
+	WRITE_LIFE_MEDIUM	= 3, /* RWH_WRITE_LIFE_MEDIUM */
+	WRITE_LIFE_LONG		= 4, /* RWH_WRITE_LIFE_LONG */
+	WRITE_LIFE_EXTREME	= 5, /* RWH_WRITE_LIFE_EXTREME */
+} __packed;
+
+static_assert(sizeof(enum rw_hint) == 1);
+
+#endif /* _LINUX_RW_HINT_H */