fsx: fix infinite/too long loops when generating ranges for clone operations

While running generic/457 I've had fsx taking a lot of CPU time and not
making any progress for over an hour. Attaching gdb to the fsx process
revealed that fsx was in the loop that generates the ranges for a clone
operation, in particular the loop seemed to never end because the range
defined by 'offset2' kept overlapping with the range defined by 'offset'.
So far this happened two times in one of my test VMs with generic/457.

Fix this by breaking out of the loop after trying 30 times, like we
currently do for dedupe operations, which results in logging the operation
as skipped.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>

diff --git a/ltp/fsx.c b/ltp/fsx.c
index 56479eda9f05a0ad16524e2773f1f30b774caf29..ab64b50ac2132e4d2fb4d7d81f3265495f29b3de 100644 (file)
--- a/ltp/fsx.c
+++ b/ltp/fsx.c
@@ -2013,16 +2013,24 @@ test(void)
                        keep_size = random() % 2;
                break;
        case OP_CLONE_RANGE:
                        keep_size = random() % 2;
                break;
        case OP_CLONE_RANGE:

-               TRIM_OFF_LEN(offset, size, file_size);
-               offset = offset & ~(block_size - 1);
-               size = size & ~(block_size - 1);
-               do {
-                       offset2 = random();
-                       TRIM_OFF(offset2, maxfilelen);
-                       offset2 = offset2 & ~(block_size - 1);
-               } while (range_overlaps(offset, offset2, size) ||
-                        offset2 + size > maxfilelen);
-               break;
+               {
+                       int tries = 0;
+
+                       TRIM_OFF_LEN(offset, size, file_size);
+                       offset = offset & ~(block_size - 1);
+                       size = size & ~(block_size - 1);
+                       do {
+                               if (tries++ >= 30) {
+                                       size = 0;
+                                       break;
+                               }
+                               offset2 = random();
+                               TRIM_OFF(offset2, maxfilelen);
+                               offset2 = offset2 & ~(block_size - 1);
+                       } while (range_overlaps(offset, offset2, size) ||
+                                offset2 + size > maxfilelen);
+                       break;
+               }

        case OP_DEDUPE_RANGE:
                {
                        int tries = 0;
        case OP_DEDUPE_RANGE:
                {
                        int tries = 0;