[PATCH] bcache: fix bch_hprint crash and improve output

[Michael Lyle <mlyle@lyle.org>]

Solve a crash where the stack is overrun when reading sysfs and
small negative values are present.  Also correct output, as before
it would output "1.10" for numbers bigger than "1.9", and negative
fractional output was incorrect.

Signed-off-by: Michael Lyle <mlyle@lyle.org>
Reported-by: Dmitry Yu Okunev <dyokunev@ut.mephi.ru>
---
 drivers/md/bcache/util.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/md/bcache/util.c b/drivers/md/bcache/util.c
index 8c3a938f4bf0..11957038c630 100644
--- a/drivers/md/bcache/util.c
+++ b/drivers/md/bcache/util.c
@@ -86,10 +86,14 @@ ssize_t bch_hprint(char *buf, int64_t v)
 	}
 
 	if (!u)
-		return sprintf(buf, "%llu", v);
+		return sprintf(buf, "%lli", v);
 
-	if (v < 100 && v > -100)
-		snprintf(dec, sizeof(dec), ".%i", t / 100);
+	if (t > 103) {
+		if (v > 0)
+			snprintf(dec, sizeof(dec), ".%i", t * 10 / 1024);
+		else
+			snprintf(dec, sizeof(dec), ".%i", 10 - (t * 10 / 1024));
+	}
 
 	return sprintf(buf, "%lli%s%c", v, dec, units[u]);
 }
-- 
2.11.0