[PATCH 4.9 192/264] uapi: rename ext2_swab() to swab() and share globally in swab.h

[Greg Kroah-Hartman]

From: Yury Norov <yury.norov@xxxxxxxxx>

[ Upstream commit d5767057c9a76a29f073dad66b7fa12a90e8c748 ]

ext2_swab() is defined locally in lib/find_bit.c However it is not
specific to ext2, neither to bitmaps.

There are many potential users of it, so rename it to just swab() and
move to include/uapi/linux/swab.h

ABI guarantees that size of unsigned long corresponds to BITS_PER_LONG,
therefore drop unneeded cast.

Link: http://lkml.kernel.org/r/20200103202846.21616-1-yury.norov@xxxxxxxxx
Signed-off-by: Yury Norov <yury.norov@xxxxxxxxx>
Cc: Allison Randal <allison@xxxxxxxxxxx>
Cc: Joe Perches <joe@xxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: William Breathitt Gray <vilhelm.gray@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 include/linux/swab.h      |    1 +
 include/uapi/linux/swab.h |   10 ++++++++++
 lib/find_bit.c            |   16 ++--------------
 3 files changed, 13 insertions(+), 14 deletions(-)

--- a/include/linux/swab.h
+++ b/include/linux/swab.h
@@ -6,6 +6,7 @@
 # define swab16 __swab16
 # define swab32 __swab32
 # define swab64 __swab64
+# define swab __swab
 # define swahw32 __swahw32
 # define swahb32 __swahb32
 # define swab16p __swab16p
--- a/include/uapi/linux/swab.h
+++ b/include/uapi/linux/swab.h
@@ -3,6 +3,7 @@
 
 #include <linux/types.h>
 #include <linux/compiler.h>
+#include <asm/bitsperlong.h>
 #include <asm/swab.h>
 
 /*
@@ -131,6 +132,15 @@ static inline __attribute_const__ __u32
 	__fswab64(x))
 #endif
 
+static __always_inline unsigned long __swab(const unsigned long y)
+{
+#if BITS_PER_LONG == 64
+	return __swab64(y);
+#else /* BITS_PER_LONG == 32 */
+	return __swab32(y);
+#endif
+}
+
 /**
  * __swahw32 - return a word-swapped 32-bit value
  * @x: value to wordswap
--- a/lib/find_bit.c
+++ b/lib/find_bit.c
@@ -133,18 +133,6 @@ EXPORT_SYMBOL(find_last_bit);
 
 #ifdef __BIG_ENDIAN
 
-/* include/linux/byteorder does not support "unsigned long" type */
-static inline unsigned long ext2_swab(const unsigned long y)
-{
-#if BITS_PER_LONG == 64
-	return (unsigned long) __swab64((u64) y);
-#elif BITS_PER_LONG == 32
-	return (unsigned long) __swab32((u32) y);
-#else
-#error BITS_PER_LONG not defined
-#endif
-}
-
 #if !defined(find_next_bit_le) || !defined(find_next_zero_bit_le)
 static unsigned long _find_next_bit_le(const unsigned long *addr,
 		unsigned long nbits, unsigned long start, unsigned long invert)
@@ -157,7 +145,7 @@ static unsigned long _find_next_bit_le(c
 	tmp = addr[start / BITS_PER_LONG] ^ invert;
 
 	/* Handle 1st word. */
-	tmp &= ext2_swab(BITMAP_FIRST_WORD_MASK(start));
+	tmp &= swab(BITMAP_FIRST_WORD_MASK(start));
 	start = round_down(start, BITS_PER_LONG);
 
 	while (!tmp) {
@@ -168,7 +156,7 @@ static unsigned long _find_next_bit_le(c
 		tmp = addr[start / BITS_PER_LONG] ^ invert;
 	}
 
-	return min(start + __ffs(ext2_swab(tmp)), nbits);
+	return min(start + __ffs(swab(tmp)), nbits);
 }
 #endif