[PATCH] ltp/fsx: avoid infinite loop while finding offset2 in clone/dedupe/copy range ops

[Eryu Guan <eguan@linux.alibaba.com>]

In CLONE/DEDUPE/COPY RANGE operations, we pick a "offset" and "size"
first, then find a suitable "offset2" by looping if there's overlap
(|offset2-offset| < size) or final file size is greater than max file
size (offset2 + size > maxfilelen).

But it's possible that there's no such suitable offset2 and we loop
forever. e.g. block_size = 4096, offset = 0, size = 4096 and maxfilelen
is a value smaller than 8212 (which could be set via '-l' option).

Fix it by making sure maxfilelen/file_size is big enough to hold 'size'
bytes from 'offset2', and just skip this operation if not.

Signed-off-by: Eryu Guan <eguan@linux.alibaba.com>
---
 ltp/fsx.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/ltp/fsx.c b/ltp/fsx.c
index 06d08e4e93f3..f6eb3308e8bc 100644
--- a/ltp/fsx.c
+++ b/ltp/fsx.c
@@ -1825,6 +1825,14 @@ do {						\
 	TRIM_LEN(off, len, size);		\
 } while (0)
 
+#define CHECK_RANGE(off, len, size)		\
+do {						\
+	if ((off + len * 2) > size) {		\
+		log5(op, offset, size, -1, FL_SKIPPED); \
+		goto out;			\
+	}					\
+} while (0)
+
 void
 cleanup(int sig)
 {
@@ -1989,6 +1997,7 @@ test(void)
 		TRIM_OFF_LEN(offset, size, file_size);
 		offset = offset & ~(block_size - 1);
 		size = size & ~(block_size - 1);
+		CHECK_RANGE(offset, size, maxfilelen);
 		do {
 			offset2 = random();
 			TRIM_OFF(offset2, maxfilelen);
@@ -2003,6 +2012,7 @@ test(void)
 			TRIM_OFF_LEN(offset, size, file_size);
 			offset = offset & ~(block_size - 1);
 			size = size & ~(block_size - 1);
+			CHECK_RANGE(offset, size, file_size);
 			do {
 				if (tries++ >= 30) {
 					size = 0;
@@ -2020,6 +2030,7 @@ test(void)
 		offset -= offset % readbdy;
 		if (o_direct)
 			size -= size % readbdy;
+		CHECK_RANGE(offset, size, maxfilelen);
 		do {
 			offset2 = random();
 			TRIM_OFF(offset2, maxfilelen);
-- 
2.14.4.44.g2045bb6