ore: Unlock r4w pages in exact reverse order of locking

The read-4-write pages are locked in address ascending order.
But where unlocked in a way easiest for coding. Fix that,
locks should be released in opposite order of locking, .i.e
descending address order.

I have not hit this dead-lock. It was found by inspecting the
dbug print-outs. I suspect there is an higher lock at caller that
protects us, but fix it regardless.

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>

diff --git a/fs/exofs/ore_raid.c b/fs/exofs/ore_raid.c
index fff2070..5f376d1 100644 (file)
--- a/fs/exofs/ore_raid.c
+++ b/fs/exofs/ore_raid.c
@@ -144,26 +144,26 @@ static void _sp2d_reset(struct __stripe_pages_2d *sp2d,
 {
        unsigned data_devs = sp2d->data_devs;
        unsigned group_width = data_devs + sp2d->parity;
-       unsigned p;
+       int p, c;
 
        if (!sp2d->needed)
                return;
 
-       for (p = 0; p < sp2d->pages_in_unit; p++) {
-               struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];
-
-               if (_1ps->write_count < group_width) {
-                       unsigned c;
+       for (c = data_devs - 1; c >= 0; --c)
+               for (p = sp2d->pages_in_unit - 1; p >= 0; --p) {
+                       struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];
 
-                       for (c = 0; c < data_devs; c++)
-                               if (_1ps->page_is_read[c]) {
-                                       struct page *page = _1ps->pages[c];
+                       if (_1ps->page_is_read[c]) {
+                               struct page *page = _1ps->pages[c];
 
-                                       r4w->put_page(priv, page);
-                                       _1ps->page_is_read[c] = false;
-                               }
+                               r4w->put_page(priv, page);
+                               _1ps->page_is_read[c] = false;
+                       }
                }
 
+       for (p = 0; p < sp2d->pages_in_unit; p++) {
+               struct __1_page_stripe *_1ps = &sp2d->_1p_stripes[p];
+
                memset(_1ps->pages, 0, group_width * sizeof(*_1ps->pages));
                _1ps->write_count = 0;
                _1ps->tx = NULL;