[v4,2/3] fs: Convert kiocb rw_hint from enum to u16

Commit Message

Adam Manzanares May 17, 2018, 8:38 p.m. UTC

From: Adam Manzanares <[e-mail]>

In order to avoid kiocb bloat for per command iopriority support, rw_hint
is converted from enum to a u16. Added a guard around ki_hint assigment.

Signed-off-by: Adam Manzanares <[e-mail]>
---
 include/linux/fs.h | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

Comments

Christoph Hellwig May 18, 2018, 4:05 p.m. UTC | #1

> +/* ki_hint changed from enum to u16, make sure rw_hint fits into u16 */

I don't think this comment is very useful.

> +static inline u16 ki_hint_valid(enum rw_hint hint)

I'd call this ki_hint_validate.

> +{
> +	if (hint > MAX_KI_HINT)
> +		return 0;
> +
> +	return hint;

Nit: kill the empty line.

Adam Manzanares May 18, 2018, 7:53 p.m. UTC | #2

On 5/18/18 9:05 AM, Christoph Hellwig wrote:
>> +/* ki_hint changed from enum to u16, make sure rw_hint fits into u16 */

> 

> I don't think this comment is very useful.

> 

>> +static inline u16 ki_hint_valid(enum rw_hint hint)

> 

> I'd call this ki_hint_validate.

> 

>> +{

>> +	if (hint > MAX_KI_HINT)

>> +		return 0;

>> +

>> +	return hint;

> 

> Nit: kill the empty line.

> 


I'll clean this up in the next revision.

Patch

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 760d8da1b6c7..7a90ce387e00 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -284,6 +284,8 @@  enum rw_hint {
 	WRITE_LIFE_EXTREME	= RWH_WRITE_LIFE_EXTREME,
 };
 
+#define MAX_KI_HINT		((1 << 16) - 1) /* ki_hint type is u16 */
+
 #define IOCB_EVENTFD		(1 << 0)
 #define IOCB_APPEND		(1 << 1)
 #define IOCB_DIRECT		(1 << 2)
@@ -299,7 +301,7 @@  struct kiocb {
 	void (*ki_complete)(struct kiocb *iocb, long ret, long ret2);
 	void			*private;
 	int			ki_flags;
-	enum rw_hint		ki_hint;
+	u16			ki_hint;
 } __randomize_layout;
 
 static inline bool is_sync_kiocb(struct kiocb *kiocb)
@@ -1927,12 +1929,21 @@  static inline enum rw_hint file_write_hint(struct file *file)
 
 static inline int iocb_flags(struct file *file);
 
+/* ki_hint changed from enum to u16, make sure rw_hint fits into u16 */
+static inline u16 ki_hint_valid(enum rw_hint hint)
+{
+	if (hint > MAX_KI_HINT)
+		return 0;
+
+	return hint;
+}
+
 static inline void init_sync_kiocb(struct kiocb *kiocb, struct file *filp)
 {
 	*kiocb = (struct kiocb) {
 		.ki_filp = filp,
 		.ki_flags = iocb_flags(filp),
-		.ki_hint = file_write_hint(filp),
+		.ki_hint = ki_hint_valid(file_write_hint(filp)),
 	};
 }