FS-Cache: Make cookie relinquishment wait for outstanding reads

Make fscache_relinquish_cookie() log a warning and wait if there are any
outstanding reads left on the cookie it was given.

Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 14 insertions, 4 deletions

diff --git a/fs/fscache/cookie.c b/fs/fscache/cookie.c
index 0666996adf80..66be9eccede0 100644
--- a/fs/fscache/cookie.c
+++ b/fs/fscache/cookie.c
@@ -442,22 +442,32 @@ void __fscache_relinquish_cookie(struct fscache_cookie *cookie, int retire)
 
         event = retire ? FSCACHE_OBJECT_EV_RETIRE : FSCACHE_OBJECT_EV_RELEASE;
 
+try_again:
         spin_lock(&cookie->lock);
 
         /* break links with all the active objects */
         while (!hlist_empty(&cookie->backing_objects)) {
+                int n_reads;
                 object = hlist_entry(cookie->backing_objects.first,
                                      struct fscache_object,
                                      cookie_link);
 
                 _debug("RELEASE OBJ%x", object->debug_id);
 
-                if (atomic_read(&object->n_reads)) {
+                set_bit(FSCACHE_COOKIE_WAITING_ON_READS, &cookie->flags);
+                n_reads = atomic_read(&object->n_reads);
+                if (n_reads) {
+                        int n_ops = object->n_ops;
+                        int n_in_progress = object->n_in_progress;
                         spin_unlock(&cookie->lock);
                         printk(KERN_ERR "FS-Cache:"
-                               " Cookie '%s' still has %d outstanding reads\n",
-                               cookie->def->name, atomic_read(&object->n_reads));
-                        BUG();
+                               " Cookie '%s' still has %d outstanding reads (%d,%d)\n",
+                               cookie->def->name,
+                               n_reads, n_ops, n_in_progress);
+                        wait_on_bit(&cookie->flags, FSCACHE_COOKIE_WAITING_ON_READS,
+                                    fscache_wait_bit, TASK_UNINTERRUPTIBLE);
+                        printk("Wait finished\n");
+                        goto try_again;
                 }
 
                 /* detach each cache object from the object cookie */