Hi,
this is an update of my patches to implement livelock avoidance for data
integrity writes using page tagging. There are some minor changes against
the previous versions:
* fixed some whitespace problems spotted checkpatch
* added WARN_ON_ONCE to catch a problem if radix_tree_range_tag_if_tagged
tags more pages than we asked
* fixed radix_tree_range_tag_if_tagged to tag at most as many pages as
we asked (it could tag one page more).
The patch now passed also XFSQA for XFS (well, several tests failed - like
192, 195, 228 ... - but they don't seem to be related - they are atime test,
ctime test, file alignment test, ...). Also the radix tree code passed through
10000 iterations of the following test I've implemented in Andrew's rtth:
void copy_tag_check(void)
{
RADIX_TREE(tree, GFP_KERNEL);
unsigned long idx[ITEMS];
unsigned long start, end, count = 0, tagged, cur, tmp;
int i;
// printf("generating radix tree indices...\n");
start = rand();
end = rand();
if (start > end && (rand() % 10)) {
cur = start;
start = end;
end = cur;
}
/* Specifically create items around the start and the end of the range
* with high probability to check for off by one errors */
cur = rand();
if (cur & 1) {
item_insert(&tree, start);
if (cur & 2) {
if (start <= end)
count++;
item_tag_set(&tree, start, 0);
}
}
if (cur & 4) {
item_insert(&tree, start-1);
if (cur & 8)
item_tag_set(&tree, start-1, 0);
}
if (cur & 16) {
item_insert(&tree, end);
if (cur & 32) {
if (start <= end)
count++;
item_tag_set(&tree, end, 0);
}
}
if (cur & 64) {
item_insert(&tree, end+1);
if (cur & 128)
item_tag_set(&tree, end+1, 0);
}
for (i = 0; i < ITEMS; i++) {
do {
idx[i] = rand();
} while (item_lookup(&tree, idx[i]));
item_insert(&tree, idx[i]);
if (rand() & 1) {
item_tag_set(&tree, idx[i], 0);
if (idx[i] >= start && idx[i] <= end)
count++;
}
/* if (i % 1000 == 0)
putchar('.'); */
}
// printf("\ncopying tags...\n");
cur = start;
tagged = radix_tree_range_tag_if_tagged(&tree, &cur, end, ITEMS, 0, 1);
// printf("checking copied tags\n");
assert(tagged == count);
check_copied_tags(&tree, start, end, idx, ITEMS, 0, 1);
/* Copy tags in several rounds */
// printf("\ncopying tags...\n");
cur = start;
do {
tmp = rand() % (count/10+2);
tagged = radix_tree_range_tag_if_tagged(&tree, &cur, end, tmp, 0
} while (tmp == tagged);
// printf("%lu %lu %lu\n", tagged, tmp, count);
// printf("checking copied tags\n");
check_copied_tags(&tree, start, end, idx, ITEMS, 0, 2);
assert(tagged < tmp);
// printf("\n");
item_kill_tree(&tree);
}
Honza
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