From c6039704c580aeac32d26d858f402be537cbe819 Mon Sep 17 00:00:00 2001 From: Nikolay Borisov Date: Fri, 8 Jun 2018 17:53:29 +0300 Subject: btrfs-progs: Add delayed refs infrastructure This commit pulls those portions of the kernel implementation of delayed refs which are necessary to have them working in user-space. I've done the following modifications: 1. Replaced all kmem_cache_alloc calls to kmalloc. 2. Removed all locking-related code, since we are single threaded in userspace. 3. Removed code which deals with data refs - delayed refs in user space are going to be used only for cowonly trees. Signed-off-by: Nikolay Borisov Signed-off-by: David Sterba --- delayed-ref.h | 208 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 208 insertions(+) create mode 100644 delayed-ref.h (limited to 'delayed-ref.h') diff --git a/delayed-ref.h b/delayed-ref.h new file mode 100644 index 00000000..30a68b2a --- /dev/null +++ b/delayed-ref.h @@ -0,0 +1,208 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) 2008 Oracle. All rights reserved. + */ + +#ifndef BTRFS_DELAYED_REF_H +#define BTRFS_DELAYED_REF_H + +#include "kerncompat.h" + +/* these are the possible values of struct btrfs_delayed_ref_node->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 ref_node; + /* + * If action is BTRFS_ADD_DELAYED_REF, also link this node to + * ref_head->ref_add_list, then we do not need to iterate the + * whole ref_head->ref_list to find BTRFS_ADD_DELAYED_REF nodes. + */ + struct list_head add_list; + + /* the starting bytenr of the extent */ + u64 bytenr; + + /* the size of the extent */ + u64 num_bytes; + + /* seq number to keep track of insertion order */ + u64 seq; + + /* ref count on this data structure */ + u64 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; + + unsigned int action:8; + unsigned int type:8; + /* is this node still in the rbtree? */ + unsigned int is_head:1; + unsigned int in_tree:1; +}; + +struct btrfs_delayed_extent_op { + struct btrfs_disk_key key; + u8 level; + bool update_key; + bool update_flags; + bool is_data; + u64 flags_to_set; +}; + +/* + * 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 { + u64 bytenr; + u64 num_bytes; + u64 refs; + + struct rb_root ref_tree; + /* accumulate add BTRFS_ADD_DELAYED_REF nodes to this ref_add_list. */ + struct list_head ref_add_list; + + struct rb_node href_node; + + struct btrfs_delayed_extent_op *extent_op; + + /* + * This is used to track the final ref_mod from all the refs associated + * with this head ref, this is not adjusted as delayed refs are run, + * this is meant to track if we need to do the csum accounting or not. + */ + int total_ref_mod; + + /* + * This is the current outstanding mod references for this bytenr. This + * is used with lookup_extent_info to get an accurate reference count + * for a bytenr, so it is adjusted as delayed refs are run so that any + * on disk reference count + ref_mod is accurate. + */ + int ref_mod; + + /* + * 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; + unsigned int is_data:1; + unsigned int is_system:1; + unsigned int processing:1; +}; + +struct btrfs_delayed_tree_ref { + struct btrfs_delayed_ref_node node; + u64 root; + u64 parent; + int level; +}; + +struct btrfs_delayed_ref_root { + /* head ref rbtree */ + struct rb_root href_root; + + /* dirty extent records */ + struct rb_root dirty_extent_root; + + /* 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 struct btrfs_delayed_extent_op * +btrfs_alloc_delayed_extent_op(void) +{ + return kmalloc(sizeof(struct btrfs_delayed_extent_op), GFP_KERNEL); +} + +static inline void +btrfs_free_delayed_extent_op(struct btrfs_delayed_extent_op *op) +{ + if (op) + kfree(op); +} + +static inline void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref) +{ + WARN_ON(ref->refs == 0); + if (--ref->refs) { + WARN_ON(ref->in_tree); + switch (ref->type) { + case BTRFS_TREE_BLOCK_REF_KEY: + case BTRFS_SHARED_BLOCK_REF_KEY: + kfree(ref); + break; + case BTRFS_EXTENT_DATA_REF_KEY: + case BTRFS_SHARED_DATA_REF_KEY: + kfree(ref); + break; + default: + BUG(); + } + } +} + +static inline void btrfs_put_delayed_ref_head(struct btrfs_delayed_ref_head *head) +{ + if (--head->refs) + kfree(head); +} + +int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info, + struct btrfs_trans_handle *trans, + u64 bytenr, u64 num_bytes, u64 parent, + u64 ref_root, int level, int action, + struct btrfs_delayed_extent_op *extent_op, + int *old_ref_mod, int *new_ref_mod); +void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans, + struct btrfs_delayed_ref_root *delayed_refs, + struct btrfs_delayed_ref_head *head); + +struct btrfs_delayed_ref_head * +btrfs_select_ref_head(struct btrfs_trans_handle *trans); + +/* + * helper functions to cast a node into its container + */ +static inline struct btrfs_delayed_tree_ref * +btrfs_delayed_node_to_tree_ref(struct btrfs_delayed_ref_node *node) +{ + return container_of(node, struct btrfs_delayed_tree_ref, node); +} +#endif -- cgit v1.2.3