fscache: Attach the index key and aux data to the cookie

Attach copies of the index key and auxiliary data to the fscache cookie so
that:

 (1) The callbacks to the netfs for this stuff can be eliminated.  This
     can simplify things in the cache as the information is still
     available, even after the cache has relinquished the cookie.

 (2) Simplifies the locking requirements of accessing the information as we
     don't have to worry about the netfs object going away on us.

 (3) The cache can do lazy updating of the coherency information on disk.
     As long as the cache is flushed before reboot/poweroff, there's no
     need to update the coherency info on disk every time it changes.

 (4) Cookies can be hashed or put in a tree as the index key is easily
     available.  This allows:

     (a) Checks for duplicate cookies can be made at the top fscache layer
     	 rather than down in the bowels of the cache backend.

     (b) Caching can be added to a netfs object that has a cookie if the
     	 cache is brought online after the netfs object is allocated.

A certain amount of space is made in the cookie for inline copies of the
data, but if it won't fit there, extra memory will be allocated for it.

The downside of this is that live cache operation requires more memory.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Anna Schumaker <anna.schumaker@netapp.com>
Tested-by: Steve Dickson <steved@redhat.com>

1 files changed, 69 insertions, 19 deletions

diff --git a/fs/fscache/cookie.c b/fs/fscache/cookie.c
index ea1f80daaff4..4d6210082a60 100644
--- a/fs/fscache/cookie.c
+++ b/fs/fscache/cookie.c
@@ -58,6 +58,8 @@ void fscache_cookie_init_once(void *_cookie)
 struct fscache_cookie *__fscache_acquire_cookie(
 	struct fscache_cookie *parent,
 	const struct fscache_cookie_def *def,
+	const void *index_key, size_t index_key_len,
+	const void *aux_data, size_t aux_data_len,
 	void *netfs_data,
 	bool enable)
 {
@@ -69,6 +71,13 @@ struct fscache_cookie *__fscache_acquire_cookie(
 	       parent ? (char *) parent->def->name : "<no-parent>",
 	       def->name, netfs_data, enable);
 
+	if (!index_key || !index_key_len || index_key_len > 255 || aux_data_len > 255)
+		return NULL;
+	if (!aux_data || !aux_data_len) {
+		aux_data = NULL;
+		aux_data_len = 0;
+	}
+
 	fscache_stat(&fscache_n_acquires);
 
 	/* if there's no parent cookie, then we don't create one here either */
@@ -79,11 +88,10 @@ struct fscache_cookie *__fscache_acquire_cookie(
 	}
 
 	/* validate the definition */
-	BUG_ON(!def->get_key);
 	BUG_ON(!def->name[0]);
 
 	BUG_ON(def->type == FSCACHE_COOKIE_TYPE_INDEX &&
-	       parent->def->type != FSCACHE_COOKIE_TYPE_INDEX);
+	       parent->type != FSCACHE_COOKIE_TYPE_INDEX);
 
 	/* allocate and initialise a cookie */
 	cookie = kmem_cache_alloc(fscache_cookie_jar, GFP_KERNEL);
@@ -93,6 +101,25 @@ struct fscache_cookie *__fscache_acquire_cookie(
 		return NULL;
 	}
 
+	cookie->key_len		= index_key_len;
+	cookie->aux_len		= aux_data_len;
+
+	if (cookie->key_len <= sizeof(cookie->inline_key)) {
+		memcpy(cookie->inline_key, index_key, cookie->key_len);
+	} else {
+		cookie->key = kmemdup(index_key, cookie->key_len, GFP_KERNEL);
+		if (!cookie->key)
+			goto nomem;
+	}
+
+	if (cookie->aux_len <= sizeof(cookie->inline_aux)) {
+		memcpy(cookie->inline_aux, aux_data, cookie->aux_len);
+	} else {
+		cookie->aux = kmemdup(aux_data, cookie->aux_len, GFP_KERNEL);
+		if (!cookie->aux)
+			goto nomem;
+	}
+
 	atomic_set(&cookie->usage, 1);
 	atomic_set(&cookie->n_children, 0);
 
@@ -108,12 +135,13 @@ struct fscache_cookie *__fscache_acquire_cookie(
 	cookie->parent		= parent;
 	cookie->netfs_data	= netfs_data;
 	cookie->flags		= (1 << FSCACHE_COOKIE_NO_DATA_YET);
-
+	cookie->type		= def->type;
+	
 	/* radix tree insertion won't use the preallocation pool unless it's
 	 * told it may not wait */
 	INIT_RADIX_TREE(&cookie->stores, GFP_NOFS & ~__GFP_DIRECT_RECLAIM);
 
-	switch (cookie->def->type) {
+	switch (cookie->type) {
 	case FSCACHE_COOKIE_TYPE_INDEX:
 		fscache_stat(&fscache_n_cookie_index);
 		break;
@@ -131,7 +159,7 @@ struct fscache_cookie *__fscache_acquire_cookie(
 		/* if the object is an index then we need do nothing more here
 		 * - we create indices on disk when we need them as an index
 		 * may exist in multiple caches */
-		if (cookie->def->type != FSCACHE_COOKIE_TYPE_INDEX) {
+		if (cookie->type != FSCACHE_COOKIE_TYPE_INDEX) {
 			if (fscache_acquire_non_index_cookie(cookie) == 0) {
 				set_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags);
 			} else {
@@ -150,6 +178,14 @@ struct fscache_cookie *__fscache_acquire_cookie(
 	fscache_stat(&fscache_n_acquires_ok);
 	_leave(" = %p", cookie);
 	return cookie;
+
+nomem:
+	if (cookie->aux_len > sizeof(cookie->inline_aux))
+		kfree(cookie->aux);
+	if (cookie->key_len > sizeof(cookie->inline_key))
+		kfree(cookie->key);
+	kmem_cache_free(fscache_cookie_jar, cookie);
+	return NULL;
 }
 EXPORT_SYMBOL(__fscache_acquire_cookie);
 
@@ -157,6 +193,7 @@ EXPORT_SYMBOL(__fscache_acquire_cookie);
  * Enable a cookie to permit it to accept new operations.
  */
 void __fscache_enable_cookie(struct fscache_cookie *cookie,
+			     const void *aux_data,
 			     bool (*can_enable)(void *data),
 			     void *data)
 {
@@ -167,12 +204,14 @@ void __fscache_enable_cookie(struct fscache_cookie *cookie,
 	wait_on_bit_lock(&cookie->flags, FSCACHE_COOKIE_ENABLEMENT_LOCK,
 			 TASK_UNINTERRUPTIBLE);
 
+	fscache_update_aux(cookie, aux_data);
+
 	if (test_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags))
 		goto out_unlock;
 
 	if (can_enable && !can_enable(data)) {
 		/* The netfs decided it didn't want to enable after all */
-	} else if (cookie->def->type != FSCACHE_COOKIE_TYPE_INDEX) {
+	} else if (cookie->type != FSCACHE_COOKIE_TYPE_INDEX) {
 		/* Wait for outstanding disablement to complete */
 		__fscache_wait_on_invalidate(cookie);
 
@@ -431,10 +470,7 @@ void __fscache_invalidate(struct fscache_cookie *cookie)
 	 * there, and if it's doing that, it may as well just retire the
 	 * cookie.
 	 */
-	ASSERTCMP(cookie->def->type, ==, FSCACHE_COOKIE_TYPE_DATAFILE);
-
-	/* We will be updating the cookie too. */
-	BUG_ON(!cookie->def->get_aux);
+	ASSERTCMP(cookie->type, ==, FSCACHE_COOKIE_TYPE_DATAFILE);
 
 	/* If there's an object, we tell the object state machine to handle the
 	 * invalidation on our behalf, otherwise there's nothing to do.
@@ -478,7 +514,7 @@ EXPORT_SYMBOL(__fscache_wait_on_invalidate);
 /*
  * update the index entries backing a cookie
  */
-void __fscache_update_cookie(struct fscache_cookie *cookie)
+void __fscache_update_cookie(struct fscache_cookie *cookie, const void *aux_data)
 {
 	struct fscache_object *object;
 
@@ -492,10 +528,10 @@ void __fscache_update_cookie(struct fscache_cookie *cookie)
 
 	_enter("{%s}", cookie->def->name);
 
-	BUG_ON(!cookie->def->get_aux);
-
 	spin_lock(&cookie->lock);
 
+	fscache_update_aux(cookie, aux_data);
+
 	if (fscache_cookie_enabled(cookie)) {
 		/* update the index entry on disk in each cache backing this
 		 * cookie.
@@ -514,7 +550,9 @@ EXPORT_SYMBOL(__fscache_update_cookie);
 /*
  * Disable a cookie to stop it from accepting new requests from the netfs.
  */
-void __fscache_disable_cookie(struct fscache_cookie *cookie, bool invalidate)
+void __fscache_disable_cookie(struct fscache_cookie *cookie,
+			      const void *aux_data,
+			      bool invalidate)
 {
 	struct fscache_object *object;
 	bool awaken = false;
@@ -533,6 +571,9 @@ void __fscache_disable_cookie(struct fscache_cookie *cookie, bool invalidate)
 
 	wait_on_bit_lock(&cookie->flags, FSCACHE_COOKIE_ENABLEMENT_LOCK,
 			 TASK_UNINTERRUPTIBLE);
+
+	fscache_update_aux(cookie, aux_data);
+
 	if (!test_and_clear_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags))
 		goto out_unlock_enable;
 
@@ -570,7 +611,7 @@ void __fscache_disable_cookie(struct fscache_cookie *cookie, bool invalidate)
 	}
 
 	/* Make sure any pending writes are cancelled. */
-	if (cookie->def->type != FSCACHE_COOKIE_TYPE_INDEX)
+	if (cookie->type != FSCACHE_COOKIE_TYPE_INDEX)
 		fscache_invalidate_writes(cookie);
 
 	/* Reset the cookie state if it wasn't relinquished */
@@ -592,7 +633,9 @@ EXPORT_SYMBOL(__fscache_disable_cookie);
  * - all dependents of this cookie must have already been unregistered
  *   (indices/files/pages)
  */
-void __fscache_relinquish_cookie(struct fscache_cookie *cookie, bool retire)
+void __fscache_relinquish_cookie(struct fscache_cookie *cookie,
+				 const void *aux_data,
+				 bool retire)
 {
 	fscache_stat(&fscache_n_relinquishes);
 	if (retire)
@@ -614,7 +657,7 @@ void __fscache_relinquish_cookie(struct fscache_cookie *cookie, bool retire)
 	if (test_and_set_bit(FSCACHE_COOKIE_RELINQUISHED, &cookie->flags))
 		BUG();
 
-	__fscache_disable_cookie(cookie, retire);
+	__fscache_disable_cookie(cookie, aux_data, retire);
 
 	/* Clear pointers back to the netfs */
 	cookie->netfs_data	= NULL;
@@ -656,6 +699,10 @@ void fscache_cookie_put(struct fscache_cookie *cookie,
 
 		parent = cookie->parent;
 		BUG_ON(!hlist_empty(&cookie->backing_objects));
+		if (cookie->aux_len > sizeof(cookie->inline_aux))
+			kfree(cookie->aux);
+		if (cookie->key_len > sizeof(cookie->inline_key))
+			kfree(cookie->key);
 		kmem_cache_free(fscache_cookie_jar, cookie);
 
 		cookie = parent;
@@ -670,7 +717,8 @@ void fscache_cookie_put(struct fscache_cookie *cookie,
  *
  * NOTE: it only serves no-index type
  */
-int __fscache_check_consistency(struct fscache_cookie *cookie)
+int __fscache_check_consistency(struct fscache_cookie *cookie,
+				const void *aux_data)
 {
 	struct fscache_operation *op;
 	struct fscache_object *object;
@@ -679,7 +727,7 @@ int __fscache_check_consistency(struct fscache_cookie *cookie)
 
 	_enter("%p,", cookie);
 
-	ASSERTCMP(cookie->def->type, ==, FSCACHE_COOKIE_TYPE_DATAFILE);
+	ASSERTCMP(cookie->type, ==, FSCACHE_COOKIE_TYPE_DATAFILE);
 
 	if (fscache_wait_for_deferred_lookup(cookie) < 0)
 		return -ERESTARTSYS;
@@ -699,6 +747,8 @@ int __fscache_check_consistency(struct fscache_cookie *cookie)
 
 	spin_lock(&cookie->lock);
 
+	fscache_update_aux(cookie, aux_data);
+
 	if (!fscache_cookie_enabled(cookie) ||
 	    hlist_empty(&cookie->backing_objects))
 		goto inconsistent;