do_mremap() untangling, part 3

[safe/jmp/linux-2.6] / mm / backing-dev.c

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 3d3accb..0e8ca03 100644 (file)
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -92,7 +92,7 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v)
                   "BdiDirtyThresh:   %8lu kB\n"
                   "DirtyThresh:      %8lu kB\n"
                   "BackgroundThresh: %8lu kB\n"
-                  "WriteBack threads:%8lu\n"
+                  "WritebackThreads: %8lu\n"
                   "b_dirty:          %8lu\n"
                   "b_io:             %8lu\n"
                   "b_more_io:        %8lu\n"
@@ -604,15 +604,36 @@ static void bdi_wb_shutdown(struct backing_dev_info *bdi)
 
        /*
         * Finally, kill the kernel threads. We don't need to be RCU
-        * safe anymore, since the bdi is gone from visibility.
+        * safe anymore, since the bdi is gone from visibility. Force
+        * unfreeze of the thread before calling kthread_stop(), otherwise
+        * it would never exet if it is currently stuck in the refrigerator.
         */
-       list_for_each_entry(wb, &bdi->wb_list, list)
+       list_for_each_entry(wb, &bdi->wb_list, list) {
+               thaw_process(wb->task);
                kthread_stop(wb->task);
+       }
+}
+
+/*
+ * This bdi is going away now, make sure that no super_blocks point to it
+ */
+static void bdi_prune_sb(struct backing_dev_info *bdi)
+{
+       struct super_block *sb;
+
+       spin_lock(&sb_lock);
+       list_for_each_entry(sb, &super_blocks, s_list) {
+               if (sb->s_bdi == bdi)
+                       sb->s_bdi = NULL;
+       }
+       spin_unlock(&sb_lock);
 }
 
 void bdi_unregister(struct backing_dev_info *bdi)
 {
        if (bdi->dev) {
+               bdi_prune_sb(bdi);
+
                if (!bdi_cap_flush_forker(bdi))
                        bdi_wb_shutdown(bdi);
                bdi_debug_unregister(bdi);