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

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 <[email protected]>

---
 ltp/fsx.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

ltp/fsx.c +11 -0

index 06d08e4e93f3..f6eb3308e8bc 100644
@@ -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);

Signature · 1 line

2.14.4.44.g2045bb6

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 <[email protected]>

---
 ltp/fsx.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

ltp/fsx.c +0 -0

index 06d08e4e93f3..f6eb3308e8bc 100644

ltp/fsx.c +4 -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);

Signature · 1 line

2.14.4.44.g2045bb6

Quoted 22 lines · Eryu Guan

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 <[email protected]>

---
 ltp/fsx.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

ltp/fsx.c +0 -0

index 06d08e4e93f3..f6eb3308e8bc 100644

ltp/fsx.c do { \ · line 1834

Quoted 10 lines

ltp/fsx.c +7 -0

@@ -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)

Eww, macros.

Worse, macros that don't parenthesize the arguments.

Worse^2, macros that require variables to be defined in the caller's scope that aren't passed as explicit parameters.

Worse^3, macros with gotos.

Why not:

static inline bool CHECK_RANGE(...)

{
	bool ret = ((off + len * 2) <= size);

	if (!ret)
		log5(...);
	return ret;
}

and then

if (!CHECK_RANGE(offset, size, maxfilelen))

	goto out;

--D

}

Quoted 31 lines

ltp/fsx.c +4 -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);

Signature · 1 line

2.14.4.44.g2045bb6