---

yaml
---
r: 168840
b: refs/heads/master
c: fee096d
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: d0e27b7808dc667f3015be0b6888f6d680e222c8
+refs/heads/master: fee096deb4f33897937b974cb2c5168bab7935be

trunk/Documentation/filesystems/caching/fscache.txt

@@ -235,6 +235,7 @@ proc files.
 		neg=N	Number of negative lookups made
 		pos=N	Number of positive lookups made
 		crt=N	Number of objects created by lookup
+		tmo=N	Number of lookups timed out and requeued
 	Updates	n=N	Number of update cookie requests seen
 		nul=N	Number of upd reqs given a NULL parent
 		run=N	Number of upd reqs granted CPU time

trunk/fs/cachefiles/interface.c

@@ -114,8 +114,9 @@ static struct fscache_object *cachefiles_alloc_object(
 
 /*
  * attempt to look up the nominated node in this cache
+ * - return -ETIMEDOUT to be scheduled again
  */
-static void cachefiles_lookup_object(struct fscache_object *_object)
+static int cachefiles_lookup_object(struct fscache_object *_object)
 {
 	struct cachefiles_lookup_data *lookup_data;
 	struct cachefiles_object *parent, *object;
@@ -145,13 +146,14 @@ static void cachefiles_lookup_object(struct fscache_object *_object)
 	    object->fscache.cookie->def->type != FSCACHE_COOKIE_TYPE_INDEX)
 		cachefiles_attr_changed(&object->fscache);
 
-	if (ret < 0) {
+	if (ret < 0 && ret != -ETIMEDOUT) {
 		printk(KERN_WARNING "CacheFiles: Lookup failed error %d\n",
 		       ret);
 		fscache_object_lookup_error(&object->fscache);
 	}
 
 	_leave(" [%d]", ret);
+	return ret;
 }
 
 /*

trunk/fs/cachefiles/namei.c

@@ -21,12 +21,6 @@
 #include <linux/security.h>
 #include "internal.h"
 
-static int cachefiles_wait_bit(void *flags)
-{
-	schedule();
-	return 0;
-}
-
 #define CACHEFILES_KEYBUF_SIZE 512
 
 /*
@@ -100,8 +94,8 @@ static noinline void cachefiles_printk_object(struct cachefiles_object *object,
 /*
  * 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;
@@ -139,8 +133,8 @@ static void cachefiles_mark_object_active(struct cachefiles_cache *cache,
 	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 */
@@ -155,13 +149,64 @@ static void cachefiles_mark_object_active(struct cachefiles_cache *cache,
 	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;
 }
 
 /*
@@ -466,12 +511,15 @@ int cachefiles_walk_to_object(struct cachefiles_object *parent,
 	}
 
 	/* 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) {
@@ -515,14 +563,18 @@ int cachefiles_walk_to_object(struct cachefiles_object *parent,
 		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);
 	rb_erase(&object->active_node, &cache->active_nodes);
 	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;
@@ -543,9 +595,6 @@ int cachefiles_walk_to_object(struct cachefiles_object *parent,
 error_out2:
 	dput(dir);
 error_out:
-	if (ret == -ENOSPC)
-		ret = -ENOBUFS;
-
 	_leave(" = error %d", -ret);
 	return ret;
 }

trunk/fs/fscache/internal.h

@@ -215,6 +215,7 @@ extern atomic_t fscache_n_object_no_alloc;
 extern atomic_t fscache_n_object_lookups;
 extern atomic_t fscache_n_object_lookups_negative;
 extern atomic_t fscache_n_object_lookups_positive;
+extern atomic_t fscache_n_object_lookups_timed_out;
 extern atomic_t fscache_n_object_created;
 extern atomic_t fscache_n_object_avail;
 extern atomic_t fscache_n_object_dead;

trunk/fs/fscache/object.c

@@ -468,6 +468,7 @@ static void fscache_lookup_object(struct fscache_object *object)
 {
 	struct fscache_cookie *cookie = object->cookie;
 	struct fscache_object *parent;
+	int ret;
 
 	_enter("");
 
@@ -493,12 +494,19 @@ static void fscache_lookup_object(struct fscache_object *object)
 
 	fscache_stat(&fscache_n_object_lookups);
 	fscache_stat(&fscache_n_cop_lookup_object);
-	object->cache->ops->lookup_object(object);
+	ret = object->cache->ops->lookup_object(object);
 	fscache_stat_d(&fscache_n_cop_lookup_object);
 
 	if (test_bit(FSCACHE_OBJECT_EV_ERROR, &object->events))
 		set_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags);
 
+	if (ret == -ETIMEDOUT) {
+		/* probably stuck behind another object, so move this one to
+		 * the back of the queue */
+		fscache_stat(&fscache_n_object_lookups_timed_out);
+		set_bit(FSCACHE_OBJECT_EV_REQUEUE, &object->events);
+	}
+
 	_leave("");
 }
 

trunk/fs/fscache/stats.c

@@ -98,6 +98,7 @@ atomic_t fscache_n_object_no_alloc;
 atomic_t fscache_n_object_lookups;
 atomic_t fscache_n_object_lookups_negative;
 atomic_t fscache_n_object_lookups_positive;
+atomic_t fscache_n_object_lookups_timed_out;
 atomic_t fscache_n_object_created;
 atomic_t fscache_n_object_avail;
 atomic_t fscache_n_object_dead;
@@ -160,10 +161,11 @@ static int fscache_stats_show(struct seq_file *m, void *v)
 		   atomic_read(&fscache_n_acquires_nobufs),
 		   atomic_read(&fscache_n_acquires_oom));
 
-	seq_printf(m, "Lookups: n=%u neg=%u pos=%u crt=%u\n",
+	seq_printf(m, "Lookups: n=%u neg=%u pos=%u crt=%u tmo=%u\n",
 		   atomic_read(&fscache_n_object_lookups),
 		   atomic_read(&fscache_n_object_lookups_negative),
 		   atomic_read(&fscache_n_object_lookups_positive),
+		   atomic_read(&fscache_n_object_lookups_timed_out),
 		   atomic_read(&fscache_n_object_created));
 
 	seq_printf(m, "Updates: n=%u nul=%u run=%u\n",

trunk/include/linux/fscache-cache.h

@@ -234,8 +234,10 @@ struct fscache_cache_ops {
 	struct fscache_object *(*alloc_object)(struct fscache_cache *cache,
 					       struct fscache_cookie *cookie);
 
-	/* look up the object for a cookie */
-	void (*lookup_object)(struct fscache_object *object);
+	/* look up the object for a cookie
+	 * - return -ETIMEDOUT to be requeued
+	 */
+	int (*lookup_object)(struct fscache_object *object);
 
 	/* finished looking up */
 	void (*lookup_complete)(struct fscache_object *object);