1 files changed, 142 insertions, 45 deletions

diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c
index 4ce818ae39ea..14ac4806e291 100644
--- a/fs/cachefiles/namei.c
+++ b/fs/cachefiles/namei.c
@@ -21,17 +21,81 @@
 #include <linux/security.h>
 #include "internal.h"
 
-static int cachefiles_wait_bit(void *flags)
+#define CACHEFILES_KEYBUF_SIZE 512
+
+/*
+ * dump debugging info about an object
+ */
+static noinline
+void __cachefiles_printk_object(struct cachefiles_object *object,
+                                const char *prefix,
+                                u8 *keybuf)
 {
-        schedule();
-        return 0;
+        struct fscache_cookie *cookie;
+        unsigned keylen, loop;
+
+        printk(KERN_ERR "%sobject: OBJ%x\n",
+               prefix, object->fscache.debug_id);
+        printk(KERN_ERR "%sobjstate=%s fl=%lx swfl=%lx ev=%lx[%lx]\n",
+               prefix, fscache_object_states[object->fscache.state],
+               object->fscache.flags, object->fscache.work.flags,
+               object->fscache.events,
+               object->fscache.event_mask & FSCACHE_OBJECT_EVENTS_MASK);
+        printk(KERN_ERR "%sops=%u inp=%u exc=%u\n",
+               prefix, object->fscache.n_ops, object->fscache.n_in_progress,
+               object->fscache.n_exclusive);
+        printk(KERN_ERR "%sparent=%p\n",
+               prefix, object->fscache.parent);
+
+        spin_lock(&object->fscache.lock);
+        cookie = object->fscache.cookie;
+        if (cookie) {
+                printk(KERN_ERR "%scookie=%p [pr=%p nd=%p fl=%lx]\n",
+                       prefix,
+                       object->fscache.cookie,
+                       object->fscache.cookie->parent,
+                       object->fscache.cookie->netfs_data,
+                       object->fscache.cookie->flags);
+                if (keybuf)
+                        keylen = cookie->def->get_key(cookie->netfs_data, keybuf,
+                                                      CACHEFILES_KEYBUF_SIZE);
+                else
+                        keylen = 0;
+        } else {
+                printk(KERN_ERR "%scookie=NULL\n", prefix);
+                keylen = 0;
+        }
+        spin_unlock(&object->fscache.lock);
+
+        if (keylen) {
+                printk(KERN_ERR "%skey=[%u] '", prefix, keylen);
+                for (loop = 0; loop < keylen; loop++)
+                        printk("%02x", keybuf[loop]);
+                printk("'\n");
+        }
+}
+
+/*
+ * dump debugging info about a pair of objects
+ */
+static noinline void cachefiles_printk_object(struct cachefiles_object *object,
+                                              struct cachefiles_object *xobject)
+{
+        u8 *keybuf;
+
+        keybuf = kmalloc(CACHEFILES_KEYBUF_SIZE, GFP_NOIO);
+        if (object)
+                __cachefiles_printk_object(object, "", keybuf);
+        if (xobject)
+                __cachefiles_printk_object(xobject, "x", keybuf);
+        kfree(keybuf);
 }
 
 /*
  * record the fact that an object is now active
  */
-static void cachefiles_mark_object_active(struct cachefiles_cache *cache,
-                                          struct cachefiles_object *object)
+static int cachefiles_mark_object_active(struct cachefiles_cache *cache,
+                                         struct cachefiles_object *object)
 {
         struct cachefiles_object *xobject;
         struct rb_node **_p, *_parent = NULL;
@@ -42,8 +106,11 @@ static void cachefiles_mark_object_active(struct cachefiles_cache *cache,
 try_again:
         write_lock(&cache->active_lock);
 
-        if (test_and_set_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags))
+        if (test_and_set_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) {
+                printk(KERN_ERR "CacheFiles: Error: Object already active\n");
+                cachefiles_printk_object(object, NULL);
                 BUG();
+        }
 
         dentry = object->dentry;
         _p = &cache->active_nodes.rb_node;
@@ -66,8 +133,8 @@ try_again:
         rb_insert_color(&object->active_node, &cache->active_nodes);
 
         write_unlock(&cache->active_lock);
-        _leave("");
-        return;
+        _leave(" = 0");
+        return 0;
 
         /* an old object from a previous incarnation is hogging the slot - we
          * need to wait for it to be destroyed */
@@ -76,44 +143,70 @@ wait_for_old_object:
                 printk(KERN_ERR "\n");
                 printk(KERN_ERR "CacheFiles: Error:"
                        " Unexpected object collision\n");
-                printk(KERN_ERR "xobject: OBJ%x\n",
-                       xobject->fscache.debug_id);
-                printk(KERN_ERR "xobjstate=%s\n",
-                       fscache_object_states[xobject->fscache.state]);
-                printk(KERN_ERR "xobjflags=%lx\n", xobject->fscache.flags);
-                printk(KERN_ERR "xobjevent=%lx [%lx]\n",
-                       xobject->fscache.events, xobject->fscache.event_mask);
-                printk(KERN_ERR "xops=%u inp=%u exc=%u\n",
-                       xobject->fscache.n_ops, xobject->fscache.n_in_progress,
-                       xobject->fscache.n_exclusive);
-                printk(KERN_ERR "xcookie=%p [pr=%p nd=%p fl=%lx]\n",
-                       xobject->fscache.cookie,
-                       xobject->fscache.cookie->parent,
-                       xobject->fscache.cookie->netfs_data,
-                       xobject->fscache.cookie->flags);
-                printk(KERN_ERR "xparent=%p\n",
-                       xobject->fscache.parent);
-                printk(KERN_ERR "object: OBJ%x\n",
-                       object->fscache.debug_id);
-                printk(KERN_ERR "cookie=%p [pr=%p nd=%p fl=%lx]\n",
-                       object->fscache.cookie,
-                       object->fscache.cookie->parent,
-                       object->fscache.cookie->netfs_data,
-                       object->fscache.cookie->flags);
-                printk(KERN_ERR "parent=%p\n",
-                       object->fscache.parent);
+                cachefiles_printk_object(object, xobject);
                 BUG();
         }
         atomic_inc(&xobject->usage);
         write_unlock(&cache->active_lock);
 
-        _debug(">>> wait");
-        wait_on_bit(&xobject->flags, CACHEFILES_OBJECT_ACTIVE,
-                    cachefiles_wait_bit, TASK_UNINTERRUPTIBLE);
-        _debug("<<< waited");
+        if (test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
+                wait_queue_head_t *wq;
+
+                signed long timeout = 60 * HZ;
+                wait_queue_t wait;
+                bool requeue;
+
+                /* if the object we're waiting for is queued for processing,
+                 * then just put ourselves on the queue behind it */
+                if (slow_work_is_queued(&xobject->fscache.work)) {
+                        _debug("queue OBJ%x behind OBJ%x immediately",
+                               object->fscache.debug_id,
+                               xobject->fscache.debug_id);
+                        goto requeue;
+                }
+
+                /* otherwise we sleep until either the object we're waiting for
+                 * is done, or the slow-work facility wants the thread back to
+                 * do other work */
+                wq = bit_waitqueue(&xobject->flags, CACHEFILES_OBJECT_ACTIVE);
+                init_wait(&wait);
+                requeue = false;
+                do {
+                        prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
+                        if (!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags))
+                                break;
+                        requeue = slow_work_sleep_till_thread_needed(
+                                &object->fscache.work, &timeout);
+                } while (timeout > 0 && !requeue);
+                finish_wait(wq, &wait);
+
+                if (requeue &&
+                    test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
+                        _debug("queue OBJ%x behind OBJ%x after wait",
+                               object->fscache.debug_id,
+                               xobject->fscache.debug_id);
+                        goto requeue;
+                }
+
+                if (timeout <= 0) {
+                        printk(KERN_ERR "\n");
+                        printk(KERN_ERR "CacheFiles: Error: Overlong"
+                               " wait for old active object to go away\n");
+                        cachefiles_printk_object(object, xobject);
+                        goto requeue;
+                }
+        }
+
+        ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags));
 
         cache->cache.ops->put_object(&xobject->fscache);
         goto try_again;
+
+requeue:
+        clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
+        cache->cache.ops->put_object(&xobject->fscache);
+        _leave(" = -ETIMEDOUT");
+        return -ETIMEDOUT;
 }
 
 /*
@@ -254,7 +347,7 @@ int cachefiles_delete_object(struct cachefiles_cache *cache,
 
         dir = dget_parent(object->dentry);
 
-        mutex_lock(&dir->d_inode->i_mutex);
+        mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
         ret = cachefiles_bury_object(cache, dir, object->dentry);
 
         dput(dir);
@@ -307,7 +400,7 @@ lookup_again:
         /* search the current directory for the element name */
         _debug("lookup '%s'", name);
 
-        mutex_lock(&dir->d_inode->i_mutex);
+        mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
 
         start = jiffies;
         next = lookup_one_len(name, dir, nlen);
@@ -418,12 +511,15 @@ lookup_again:
         }
 
         /* note that we're now using this object */
-        cachefiles_mark_object_active(cache, object);
+        ret = cachefiles_mark_object_active(cache, object);
 
         mutex_unlock(&dir->d_inode->i_mutex);
         dput(dir);
         dir = NULL;
 
+        if (ret == -ETIMEDOUT)
+                goto mark_active_timed_out;
+
         _debug("=== OBTAINED_OBJECT ===");
 
         if (object->new) {
@@ -467,6 +563,10 @@ create_error:
                 cachefiles_io_error(cache, "Create/mkdir failed");
         goto error;
 
+mark_active_timed_out:
+        _debug("mark active timed out");
+        goto release_dentry;
+
 check_error:
         _debug("check error %d", ret);
         write_lock(&cache->active_lock);
@@ -474,7 +574,7 @@ check_error:
         clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
         wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE);
         write_unlock(&cache->active_lock);
-
+release_dentry:
         dput(object->dentry);
         object->dentry = NULL;
         goto error_out;
@@ -495,9 +595,6 @@ error:
 error_out2:
         dput(dir);
 error_out:
-        if (ret == -ENOSPC)
-                ret = -ENOBUFS;
-
         _leave(" = error %d", -ret);
         return ret;
 }