David Wysochanski <dwysocha@xxxxxxxxxx> wrote:
> Looks like fscache_shape_request() overrides any 'max_pages' value (actually
> it is cachefiles_shape_request) , so it's unclear why the netfs would pass
> in a 'max_pages' if it is not honored - seems like a bug maybe or it's not
> obvious
I think the problem is that cachefiles_shape_request() is applying the limit
too early. It's using it to cut down the number of pages in the original
request (only applicable to readpages), but then the shaping to fit cache
granules can exceed that, so it needs to be applied later also.
Does the attached patch help?
David
---
diff --git a/fs/cachefiles/content-map.c b/fs/cachefiles/content-map.c
index 2bfba2e41c39..ce05cf1d9a6e 100644
--- a/fs/cachefiles/content-map.c
+++ b/fs/cachefiles/content-map.c
@@ -134,7 +134,8 @@ void cachefiles_shape_request(struct fscache_object *obj,
_enter("{%lx,%lx,%x},%llx,%d",
start, end, max_pages, i_size, shape->for_write);
- if (start >= CACHEFILES_SIZE_LIMIT / PAGE_SIZE) {
+ if (start >= CACHEFILES_SIZE_LIMIT / PAGE_SIZE ||
+ max_pages < CACHEFILES_GRAN_PAGES) {
shape->to_be_done = FSCACHE_READ_FROM_SERVER;
return;
}
@@ -144,10 +145,6 @@ void cachefiles_shape_request(struct fscache_object *obj,
if (shape->i_size > CACHEFILES_SIZE_LIMIT)
i_size = CACHEFILES_SIZE_LIMIT;
- max_pages = round_down(max_pages, CACHEFILES_GRAN_PAGES);
- if (end - start > max_pages)
- end = start + max_pages;
-
granule = start / CACHEFILES_GRAN_PAGES;
if (granule / 8 >= object->content_map_size) {
cachefiles_expand_content_map(object, i_size);
@@ -185,6 +182,10 @@ void cachefiles_shape_request(struct fscache_object *obj,
start = round_down(start, CACHEFILES_GRAN_PAGES);
end = round_up(end, CACHEFILES_GRAN_PAGES);
+ /* Trim to the maximum size the netfs supports */
+ if (end - start > max_pages)
+ end = round_down(start + max_pages, CACHEFILES_GRAN_PAGES);
+
/* But trim to the end of the file and the starting page */
eof = (i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
if (eof <= shape->proposed_start)
