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Subject[PATCH v4 2/3] fs: Convert kiocb rw_hint from enum to u16
Date
From: Adam Manzanares <adam.manzanares@wdc.com>

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 <adam.manzanares@wdc.com>
---
include/linux/fs.h | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)

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)),
};
}

--
2.15.1
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