[RFC v2 10/17] block: optimize blk_status <=> errno conversion

[Andreas Gruenbacher <agruenba@redhat.com>]

Handle the errno_to_blk_status(0) case inline so that the compiler can
optimize when it knows that errno is not 0.  Likewise for
blk_status_to_errno(BLK_STATUS_OK).

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
---
 block/blk-core.c       | 11 ++++++-----
 include/linux/blkdev.h | 18 ++++++++++++++++--
 2 files changed, 22 insertions(+), 7 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 9b3100d171b7..381bdf66045b 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -133,7 +133,6 @@ inline const char *blk_op_str(enum req_op op)
 EXPORT_SYMBOL_GPL(blk_op_str);
 
 #define blk_errors(_)									\
-	_(BLK_STS_OK,			0,		"")				\
 	_(BLK_STS_NOTSUPP,		-EOPNOTSUPP,	"operation not supported")	\
 	_(BLK_STS_TIMEOUT,		-ETIMEDOUT,	"timeout")			\
 	_(BLK_STS_NOSPC,		-ENOSPC,	"critical space allocation")	\
@@ -159,7 +158,7 @@ EXPORT_SYMBOL_GPL(blk_op_str);
 											\
 	_(BLK_STS_INVAL,		-EINVAL,	"invalid")
 
-blk_status_t errno_to_blk_status(int errno)
+blk_status_t __errno_to_blk_status(int errno)
 {
 	switch(errno) {
 #define _(_status, _errno, _name)		\
@@ -171,9 +170,9 @@ blk_status_t errno_to_blk_status(int errno)
 		return BLK_STS_IOERR;
 	}
 }
-EXPORT_SYMBOL_GPL(errno_to_blk_status);
+EXPORT_SYMBOL_GPL(__errno_to_blk_status);
 
-int blk_status_to_errno(blk_status_t status)
+int __blk_status_to_errno(blk_status_t status)
 {
 	switch(status) {
 #define _(_status, _errno, _name)		\
@@ -185,11 +184,13 @@ int blk_status_to_errno(blk_status_t status)
 		return -EIO;
 	}
 }
-EXPORT_SYMBOL_GPL(blk_status_to_errno);
+EXPORT_SYMBOL_GPL(__blk_status_to_errno);
 
 const char *blk_status_to_str(blk_status_t status)
 {
 	switch(status) {
+	case BLK_STS_OK:
+		return "";
 #define _(_status, _errno, _name)		\
 	case _status:				\
 		return _name;
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 70b671a9a7f7..a2451fbd53a8 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1011,8 +1011,22 @@ extern void blk_sync_queue(struct request_queue *q);
 /* Helper to convert REQ_OP_XXX to its string format XXX */
 extern const char *blk_op_str(enum req_op op);
 
-int blk_status_to_errno(blk_status_t status);
-blk_status_t errno_to_blk_status(int errno);
+int __blk_status_to_errno(blk_status_t status);
+static inline int blk_status_to_errno(blk_status_t status)
+{
+	if (status == BLK_STS_OK)
+		return 0;
+	return __blk_status_to_errno(status);
+}
+
+blk_status_t __errno_to_blk_status(int errno);
+static inline blk_status_t errno_to_blk_status(int errno)
+{
+	if (errno == 0)
+		return BLK_STS_OK;
+	return __errno_to_blk_status(errno);
+}
+
 const char *blk_status_to_str(blk_status_t status);
 
 /* only poll the hardware once, don't continue until a completion was found */
-- 
2.52.0