1 files changed, 193 insertions, 0 deletions

diff --git a/fs/btrfs/delayed-ref.h b/fs/btrfs/delayed-ref.h
new file mode 100644
index 000000000000..3bec2ff0b15c
--- /dev/null
+++ b/fs/btrfs/delayed-ref.h
@@ -0,0 +1,193 @@
+/*
+ * Copyright (C) 2008 Oracle.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+#ifndef __DELAYED_REF__
+#define __DELAYED_REF__
+
+/* these are the possible values of struct btrfs_delayed_ref->action */
+#define BTRFS_ADD_DELAYED_REF    1 /* add one backref to the tree */
+#define BTRFS_DROP_DELAYED_REF   2 /* delete one backref from the tree */
+#define BTRFS_ADD_DELAYED_EXTENT 3 /* record a full extent allocation */
+#define BTRFS_UPDATE_DELAYED_HEAD 4 /* not changing ref count on head ref */
+
+struct btrfs_delayed_ref_node {
+        struct rb_node rb_node;
+
+        /* the starting bytenr of the extent */
+        u64 bytenr;
+
+        /* the parent our backref will point to */
+        u64 parent;
+
+        /* the size of the extent */
+        u64 num_bytes;
+
+        /* ref count on this data structure */
+        atomic_t refs;
+
+        /*
+         * how many refs is this entry adding or deleting.  For
+         * head refs, this may be a negative number because it is keeping
+         * track of the total mods done to the reference count.
+         * For individual refs, this will always be a positive number
+         *
+         * It may be more than one, since it is possible for a single
+         * parent to have more than one ref on an extent
+         */
+        int ref_mod;
+
+        /* is this node still in the rbtree? */
+        unsigned int in_tree:1;
+};
+
+/*
+ * the head refs are used to hold a lock on a given extent, which allows us
+ * to make sure that only one process is running the delayed refs
+ * at a time for a single extent.  They also store the sum of all the
+ * reference count modifications we've queued up.
+ */
+struct btrfs_delayed_ref_head {
+        struct btrfs_delayed_ref_node node;
+
+        /*
+         * the mutex is held while running the refs, and it is also
+         * held when checking the sum of reference modifications.
+         */
+        struct mutex mutex;
+
+        struct list_head cluster;
+
+        /*
+         * when a new extent is allocated, it is just reserved in memory
+         * The actual extent isn't inserted into the extent allocation tree
+         * until the delayed ref is processed.  must_insert_reserved is
+         * used to flag a delayed ref so the accounting can be updated
+         * when a full insert is done.
+         *
+         * It is possible the extent will be freed before it is ever
+         * inserted into the extent allocation tree.  In this case
+         * we need to update the in ram accounting to properly reflect
+         * the free has happened.
+         */
+        unsigned int must_insert_reserved:1;
+};
+
+struct btrfs_delayed_ref {
+        struct btrfs_delayed_ref_node node;
+
+        /* the root objectid our ref will point to */
+        u64 root;
+
+        /* the generation for the backref */
+        u64 generation;
+
+        /* owner_objectid of the backref  */
+        u64 owner_objectid;
+
+        /* operation done by this entry in the rbtree */
+        u8 action;
+
+        /* if pin == 1, when the extent is freed it will be pinned until
+         * transaction commit
+         */
+        unsigned int pin:1;
+};
+
+struct btrfs_delayed_ref_root {
+        struct rb_root root;
+
+        /* this spin lock protects the rbtree and the entries inside */
+        spinlock_t lock;
+
+        /* how many delayed ref updates we've queued, used by the
+         * throttling code
+         */
+        unsigned long num_entries;
+
+        /* total number of head nodes in tree */
+        unsigned long num_heads;
+
+        /* total number of head nodes ready for processing */
+        unsigned long num_heads_ready;
+
+        /*
+         * set when the tree is flushing before a transaction commit,
+         * used by the throttling code to decide if new updates need
+         * to be run right away
+         */
+        int flushing;
+
+        u64 run_delayed_start;
+};
+
+static inline void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref)
+{
+        WARN_ON(atomic_read(&ref->refs) == 0);
+        if (atomic_dec_and_test(&ref->refs)) {
+                WARN_ON(ref->in_tree);
+                kfree(ref);
+        }
+}
+
+int btrfs_add_delayed_ref(struct btrfs_trans_handle *trans,
+                          u64 bytenr, u64 num_bytes, u64 parent, u64 ref_root,
+                          u64 ref_generation, u64 owner_objectid, int action,
+                          int pin);
+
+struct btrfs_delayed_ref_head *
+btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr);
+int btrfs_delayed_ref_pending(struct btrfs_trans_handle *trans, u64 bytenr);
+int btrfs_lookup_extent_ref(struct btrfs_trans_handle *trans,
+                            struct btrfs_root *root, u64 bytenr,
+                            u64 num_bytes, u32 *refs);
+int btrfs_update_delayed_ref(struct btrfs_trans_handle *trans,
+                          u64 bytenr, u64 num_bytes, u64 orig_parent,
+                          u64 parent, u64 orig_ref_root, u64 ref_root,
+                          u64 orig_ref_generation, u64 ref_generation,
+                          u64 owner_objectid, int pin);
+int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
+                           struct btrfs_delayed_ref_head *head);
+int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans,
+                           struct list_head *cluster, u64 search_start);
+/*
+ * a node might live in a head or a regular ref, this lets you
+ * test for the proper type to use.
+ */
+static int btrfs_delayed_ref_is_head(struct btrfs_delayed_ref_node *node)
+{
+        return node->parent == (u64)-1;
+}
+
+/*
+ * helper functions to cast a node into its container
+ */
+static inline struct btrfs_delayed_ref *
+btrfs_delayed_node_to_ref(struct btrfs_delayed_ref_node *node)
+{
+        WARN_ON(btrfs_delayed_ref_is_head(node));
+        return container_of(node, struct btrfs_delayed_ref, node);
+
+}
+
+static inline struct btrfs_delayed_ref_head *
+btrfs_delayed_node_to_head(struct btrfs_delayed_ref_node *node)
+{
+        WARN_ON(!btrfs_delayed_ref_is_head(node));
+        return container_of(node, struct btrfs_delayed_ref_head, node);
+
+}
+#endif