[PATCH v3] erofs-utils: use cmpsgn(x, y) for standardized large value comparsion

[Gao Xiang via Linux-erofs]

Previously, roundup(bb->buffers.off % EROFS_BLKSIZ, alignsize)
+ incr + extrasize is an unsigned 64bit value and sgn(x) didn't
work properly. Fix it.

Fixes: b0ca535297b6 ("erofs-utils: support 64-bit internal buffer cache")
Signed-off-by: Gao Xiang <hsiang...@aol.com>
---
change since v2:
 - update an indention suggested by Guifu.

 include/erofs/defs.h | 5 +++--
 lib/cache.c          | 6 +++---
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/include/erofs/defs.h b/include/erofs/defs.h
index 15db4e3..d3c1156 100644
--- a/include/erofs/defs.h
+++ b/include/erofs/defs.h
@@ -136,9 +136,10 @@ typedef int64_t         s64;
        type __max2 = (y);                      \
        __max1 > __max2 ? __max1: __max2; })
 
-#define sgn(x) ({              \
+#define cmpsgn(x, y) ({                \
        typeof(x) _x = (x);     \
-(_x > 0) - (_x < 0); })
+       typeof(y) _y = (y);     \
+       (_x > _y) - (_x < _y); })
 
 #define ARRAY_SIZE(arr)        (sizeof(arr) / sizeof((arr)[0]))
 
diff --git a/lib/cache.c b/lib/cache.c
index 41d2d5d..e61b201 100644
--- a/lib/cache.c
+++ b/lib/cache.c
@@ -80,9 +80,9 @@ static int __erofs_battach(struct erofs_buffer_block *bb,
                           bool dryrun)
 {
        const erofs_off_t alignedoffset = roundup(bb->buffers.off, alignsize);
-       const int oob = sgn(roundup(bb->buffers.off % EROFS_BLKSIZ,
-                                   alignsize) + incr + extrasize -
-                           EROFS_BLKSIZ);
+       const int oob = cmpsgn(roundup(bb->buffers.off % EROFS_BLKSIZ,
+                                      alignsize) + incr + extrasize,
+                              EROFS_BLKSIZ);
        bool tailupdate = false;
        erofs_blk_t blkaddr;
 
-- 
2.17.1