SUNRPC: Drop all entries from cache_detail when cache_purge()

User always free the cache_detail after sunrpc_destroy_cache_detail(),
so, it must cleanup up entries that left in the cache_detail,
otherwise, NULL reference may be caused when using the left entries.

Also, NeriBrown suggests "write a stand-alone cache_purge()."

v3, move the cache_fresh_unlocked() out of write lock,
v2, a stand-alone cache_purge(), not only for sunrpc_destroy_cache_detail

Signed-off-by: Kinglong Mee <kinglongmee@gmail.com>
Reviewed-by: NeilBrown <neilb@suse.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 26 insertions, 15 deletions

diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c
index 502b9fe9817b..f5d6c60aae26 100644
--- a/net/sunrpc/cache.c
+++ b/net/sunrpc/cache.c
@@ -362,11 +362,6 @@ void sunrpc_destroy_cache_detail(struct cache_detail *cd)
         cache_purge(cd);
         spin_lock(&cache_list_lock);
         write_lock(&cd->hash_lock);
-        if (cd->entries) {
-                write_unlock(&cd->hash_lock);
-                spin_unlock(&cache_list_lock);
-                goto out;
-        }
         if (current_detail == cd)
                 current_detail = NULL;
         list_del_init(&cd->others);
@@ -376,9 +371,6 @@ void sunrpc_destroy_cache_detail(struct cache_detail *cd)
                 /* module must be being unloaded so its safe to kill the worker */
                 cancel_delayed_work_sync(&cache_cleaner);
         }
-        return;
-out:
-        printk(KERN_ERR "RPC: failed to unregister %s cache\n", cd->name);
 }
 EXPORT_SYMBOL_GPL(sunrpc_destroy_cache_detail);
 
@@ -497,13 +489,32 @@ EXPORT_SYMBOL_GPL(cache_flush);
 
 void cache_purge(struct cache_detail *detail)
 {
-        time_t now = seconds_since_boot();
-        if (detail->flush_time >= now)
-                now = detail->flush_time + 1;
-        /* 'now' is the maximum value any 'last_refresh' can have */
-        detail->flush_time = now;
-        detail->nextcheck = seconds_since_boot();
-        cache_flush();
+        struct cache_head *ch = NULL;
+        struct hlist_head *head = NULL;
+        struct hlist_node *tmp = NULL;
+        int i = 0;
+
+        write_lock(&detail->hash_lock);
+        if (!detail->entries) {
+                write_unlock(&detail->hash_lock);
+                return;
+        }
+
+        dprintk("RPC: %d entries in %s cache\n", detail->entries, detail->name);
+        for (i = 0; i < detail->hash_size; i++) {
+                head = &detail->hash_table[i];
+                hlist_for_each_entry_safe(ch, tmp, head, cache_list) {
+                        hlist_del_init(&ch->cache_list);
+                        detail->entries--;
+
+                        set_bit(CACHE_CLEANED, &ch->flags);
+                        write_unlock(&detail->hash_lock);
+                        cache_fresh_unlocked(ch, detail);
+                        cache_put(ch, detail);
+                        write_lock(&detail->hash_lock);
+                }
+        }
+        write_unlock(&detail->hash_lock);
 }
 EXPORT_SYMBOL_GPL(cache_purge);