delayed-ref.h

  1/* SPDX-License-Identifier: GPL-2.0 */
  2/*
  3 * Copyright (C) 2008 Oracle.  All rights reserved.
  4 */
  5
  6#ifndef BTRFS_DELAYED_REF_H
  7#define BTRFS_DELAYED_REF_H
  8
  9#include <linux/types.h>
 10#include <linux/refcount.h>
 11#include <linux/list.h>
 12#include <linux/rbtree.h>
 13#include <linux/mutex.h>
 14#include <linux/spinlock.h>
 15#include <linux/slab.h>
 16#include <uapi/linux/btrfs_tree.h>
 17#include "fs.h"
 18#include "messages.h"
 19
 20struct btrfs_trans_handle;
 21struct btrfs_fs_info;
 22
 23/* these are the possible values of struct btrfs_delayed_ref_node->action */
 24enum btrfs_delayed_ref_action {
 25	/* Add one backref to the tree */
 26	BTRFS_ADD_DELAYED_REF = 1,
 27	/* Delete one backref from the tree */
 28	BTRFS_DROP_DELAYED_REF,
 29	/* Record a full extent allocation */
 30	BTRFS_ADD_DELAYED_EXTENT,
 31	/* Not changing ref count on head ref */
 32	BTRFS_UPDATE_DELAYED_HEAD,
 33} __packed;
 34
 35struct btrfs_data_ref {
 36	/* For EXTENT_DATA_REF */
 37
 38	/* Inode which refers to this data extent */
 39	u64 objectid;
 40
 41	/*
 42	 * file_offset - extent_offset
 43	 *
 44	 * file_offset is the key.offset of the EXTENT_DATA key.
 45	 * extent_offset is btrfs_file_extent_offset() of the EXTENT_DATA data.
 46	 */
 47	u64 offset;
 48};
 49
 50struct btrfs_tree_ref {
 51	/*
 52	 * Level of this tree block.
 53	 *
 54	 * Shared for skinny (TREE_BLOCK_REF) and normal tree ref.
 55	 */
 56	int level;
 57
 58	/* For non-skinny metadata, no special member needed */
 59};
 60
 61struct btrfs_delayed_ref_node {
 62	struct rb_node ref_node;
 63	/*
 64	 * If action is BTRFS_ADD_DELAYED_REF, also link this node to
 65	 * ref_head->ref_add_list, then we do not need to iterate the
 66	 * refs rbtree in the corresponding delayed ref head
 67	 * (struct btrfs_delayed_ref_head::ref_tree).
 68	 */
 69	struct list_head add_list;
 70
 71	/* the starting bytenr of the extent */
 72	u64 bytenr;
 73
 74	/* the size of the extent */
 75	u64 num_bytes;
 76
 77	/* seq number to keep track of insertion order */
 78	u64 seq;
 79
 80	/* The ref_root for this ref */
 81	u64 ref_root;
 82
 83	/*
 84	 * The parent for this ref, if this isn't set the ref_root is the
 85	 * reference owner.
 86	 */
 87	u64 parent;
 88
 89	/* ref count on this data structure */
 90	refcount_t refs;
 91
 92	/*
 93	 * how many refs is this entry adding or deleting.  For
 94	 * head refs, this may be a negative number because it is keeping
 95	 * track of the total mods done to the reference count.
 96	 * For individual refs, this will always be a positive number
 97	 *
 98	 * It may be more than one, since it is possible for a single
 99	 * parent to have more than one ref on an extent
100	 */
101	int ref_mod;
102
103	unsigned int action:8;
104	unsigned int type:8;
105
106	union {
107		struct btrfs_tree_ref tree_ref;
108		struct btrfs_data_ref data_ref;
109	};
110};
111
112struct btrfs_delayed_extent_op {
113	struct btrfs_disk_key key;
114	bool update_key;
115	bool update_flags;
116	u64 flags_to_set;
117};
118
119/*
120 * the head refs are used to hold a lock on a given extent, which allows us
121 * to make sure that only one process is running the delayed refs
122 * at a time for a single extent.  They also store the sum of all the
123 * reference count modifications we've queued up.
124 */
125struct btrfs_delayed_ref_head {
126	u64 bytenr;
127	u64 num_bytes;
128	/*
129	 * the mutex is held while running the refs, and it is also
130	 * held when checking the sum of reference modifications.
131	 */
132	struct mutex mutex;
133
134	refcount_t refs;
135
136	/* Protects 'ref_tree' and 'ref_add_list'. */
137	spinlock_t lock;
138	struct rb_root_cached ref_tree;
139	/* accumulate add BTRFS_ADD_DELAYED_REF nodes to this ref_add_list. */
140	struct list_head ref_add_list;
141
142	struct btrfs_delayed_extent_op *extent_op;
143
144	/*
145	 * This is used to track the final ref_mod from all the refs associated
146	 * with this head ref, this is not adjusted as delayed refs are run,
147	 * this is meant to track if we need to do the csum accounting or not.
148	 */
149	int total_ref_mod;
150
151	/*
152	 * This is the current outstanding mod references for this bytenr.  This
153	 * is used with lookup_extent_info to get an accurate reference count
154	 * for a bytenr, so it is adjusted as delayed refs are run so that any
155	 * on disk reference count + ref_mod is accurate.
156	 */
157	int ref_mod;
158
159	/*
160	 * The root that triggered the allocation when must_insert_reserved is
161	 * set to true.
162	 */
163	u64 owning_root;
164
165	/*
166	 * Track reserved bytes when setting must_insert_reserved.  On success
167	 * or cleanup, we will need to free the reservation.
168	 */
169	u64 reserved_bytes;
170
171	/* Tree block level, for metadata only. */
172	u8 level;
173
174	/*
175	 * when a new extent is allocated, it is just reserved in memory
176	 * The actual extent isn't inserted into the extent allocation tree
177	 * until the delayed ref is processed.  must_insert_reserved is
178	 * used to flag a delayed ref so the accounting can be updated
179	 * when a full insert is done.
180	 *
181	 * It is possible the extent will be freed before it is ever
182	 * inserted into the extent allocation tree.  In this case
183	 * we need to update the in ram accounting to properly reflect
184	 * the free has happened.
185	 */
186	bool must_insert_reserved;
187
188	bool is_data;
189	bool is_system;
190	bool processing;
191	/*
192	 * Indicate if it's currently in the data structure that tracks head
193	 * refs (struct btrfs_delayed_ref_root::head_refs).
194	 */
195	bool tracked;
196};
197
198enum btrfs_delayed_ref_flags {
199	/* Indicate that we are flushing delayed refs for the commit */
200	BTRFS_DELAYED_REFS_FLUSHING,
201};
202
203struct btrfs_delayed_ref_root {
204	/*
205	 * Track head references.
206	 * The keys correspond to the logical address of the extent ("bytenr")
207	 * right shifted by fs_info->sectorsize_bits. This is both to get a more
208	 * dense index space (optimizes xarray structure) and because indexes in
209	 * xarrays are of "unsigned long" type, meaning they are 32 bits wide on
210	 * 32 bits platforms, limiting the extent range to 4G which is too low
211	 * and makes it unusable (truncated index values) on 32 bits platforms.
212	 * Protected by the spinlock 'lock' defined below.
213	 */
214	struct xarray head_refs;
215
216	/*
217	 * Track dirty extent records.
218	 * The keys correspond to the logical address of the extent ("bytenr")
219	 * right shifted by fs_info->sectorsize_bits, for same reasons as above.
220	 */
221	struct xarray dirty_extents;
222
223	/*
224	 * Protects the xarray head_refs, its entries and the following fields:
225	 * num_heads, num_heads_ready, pending_csums and run_delayed_start.
226	 */
227	spinlock_t lock;
228
229	/* Total number of head refs, protected by the spinlock 'lock'. */
230	unsigned long num_heads;
231
232	/*
233	 * Total number of head refs ready for processing, protected by the
234	 * spinlock 'lock'.
235	 */
236	unsigned long num_heads_ready;
237
238	/*
239	 * Track space reserved for deleting csums of data extents.
240	 * Protected by the spinlock 'lock'.
241	 */
242	u64 pending_csums;
243
244	unsigned long flags;
245
246	/*
247	 * Track from which bytenr to start searching ref heads.
248	 * Protected by the spinlock 'lock'.
249	 */
250	u64 run_delayed_start;
251
252	/*
253	 * To make qgroup to skip given root.
254	 * This is for snapshot, as btrfs_qgroup_inherit() will manually
255	 * modify counters for snapshot and its source, so we should skip
256	 * the snapshot in new_root/old_roots or it will get calculated twice
257	 */
258	u64 qgroup_to_skip;
259};
260
261enum btrfs_ref_type {
262	BTRFS_REF_NOT_SET,
263	BTRFS_REF_DATA,
264	BTRFS_REF_METADATA,
265} __packed;
266
267struct btrfs_ref {
268	enum btrfs_ref_type type;
269	enum btrfs_delayed_ref_action action;
270
271	/*
272	 * Whether this extent should go through qgroup record.
273	 *
274	 * Normally false, but for certain cases like delayed subtree scan,
275	 * setting this flag can hugely reduce qgroup overhead.
276	 */
277	bool skip_qgroup;
278
279	u64 bytenr;
280	u64 num_bytes;
281	u64 owning_root;
282
283	/*
284	 * The root that owns the reference for this reference, this will be set
285	 * or ->parent will be set, depending on what type of reference this is.
286	 */
287	u64 ref_root;
288
289	/* Bytenr of the parent tree block */
290	u64 parent;
291	union {
292		struct btrfs_data_ref data_ref;
293		struct btrfs_tree_ref tree_ref;
294	};
295
296#ifdef CONFIG_BTRFS_DEBUG
297	/* Through which root is this modification. */
298	u64 real_root;
299#endif
300};
301
302extern struct kmem_cache *btrfs_delayed_ref_head_cachep;
303extern struct kmem_cache *btrfs_delayed_ref_node_cachep;
304extern struct kmem_cache *btrfs_delayed_extent_op_cachep;
305
306int __init btrfs_delayed_ref_init(void);
307void __cold btrfs_delayed_ref_exit(void);
308
309static inline u64 btrfs_calc_delayed_ref_bytes(const struct btrfs_fs_info *fs_info,
310					       int num_delayed_refs)
311{
312	u64 num_bytes;
313
314	num_bytes = btrfs_calc_insert_metadata_size(fs_info, num_delayed_refs);
315
316	/*
317	 * We have to check the mount option here because we could be enabling
318	 * the free space tree for the first time and don't have the compat_ro
319	 * option set yet.
320	 *
321	 * We need extra reservations if we have the free space tree because
322	 * we'll have to modify that tree as well.
323	 */
324	if (btrfs_test_opt(fs_info, FREE_SPACE_TREE))
325		num_bytes *= 2;
326
327	return num_bytes;
328}
329
330static inline u64 btrfs_calc_delayed_ref_csum_bytes(const struct btrfs_fs_info *fs_info,
331						    int num_csum_items)
332{
333	/*
334	 * Deleting csum items does not result in new nodes/leaves and does not
335	 * require changing the free space tree, only the csum tree, so this is
336	 * all we need.
337	 */
338	return btrfs_calc_metadata_size(fs_info, num_csum_items);
339}
340
341void btrfs_init_tree_ref(struct btrfs_ref *generic_ref, int level, u64 mod_root,
342			 bool skip_qgroup);
343void btrfs_init_data_ref(struct btrfs_ref *generic_ref, u64 ino, u64 offset,
344			 u64 mod_root, bool skip_qgroup);
345
346static inline struct btrfs_delayed_extent_op *
347btrfs_alloc_delayed_extent_op(void)
348{
349	return kmem_cache_alloc(btrfs_delayed_extent_op_cachep, GFP_NOFS);
350}
351
352static inline void
353btrfs_free_delayed_extent_op(struct btrfs_delayed_extent_op *op)
354{
355	if (op)
356		kmem_cache_free(btrfs_delayed_extent_op_cachep, op);
357}
358
359void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref);
360
361static inline u64 btrfs_ref_head_to_space_flags(
362				struct btrfs_delayed_ref_head *head_ref)
363{
364	if (head_ref->is_data)
365		return BTRFS_BLOCK_GROUP_DATA;
366	else if (head_ref->is_system)
367		return BTRFS_BLOCK_GROUP_SYSTEM;
368	return BTRFS_BLOCK_GROUP_METADATA;
369}
370
371static inline void btrfs_put_delayed_ref_head(struct btrfs_delayed_ref_head *head)
372{
373	if (refcount_dec_and_test(&head->refs))
374		kmem_cache_free(btrfs_delayed_ref_head_cachep, head);
375}
376
377int btrfs_add_delayed_tree_ref(struct btrfs_trans_handle *trans,
378			       struct btrfs_ref *generic_ref,
379			       struct btrfs_delayed_extent_op *extent_op);
380int btrfs_add_delayed_data_ref(struct btrfs_trans_handle *trans,
381			       struct btrfs_ref *generic_ref,
382			       u64 reserved);
383int btrfs_add_delayed_extent_op(struct btrfs_trans_handle *trans,
384				u64 bytenr, u64 num_bytes, u8 level,
385				struct btrfs_delayed_extent_op *extent_op);
386void btrfs_merge_delayed_refs(struct btrfs_fs_info *fs_info,
387			      struct btrfs_delayed_ref_root *delayed_refs,
388			      struct btrfs_delayed_ref_head *head);
389
390struct btrfs_delayed_ref_head *
391btrfs_find_delayed_ref_head(const struct btrfs_fs_info *fs_info,
392			    struct btrfs_delayed_ref_root *delayed_refs,
393			    u64 bytenr);
394static inline void btrfs_delayed_ref_unlock(struct btrfs_delayed_ref_head *head)
395{
396	mutex_unlock(&head->mutex);
397}
398void btrfs_delete_ref_head(const struct btrfs_fs_info *fs_info,
399			   struct btrfs_delayed_ref_root *delayed_refs,
400			   struct btrfs_delayed_ref_head *head);
401
402struct btrfs_delayed_ref_head *btrfs_select_ref_head(
403		const struct btrfs_fs_info *fs_info,
404		struct btrfs_delayed_ref_root *delayed_refs);
405void btrfs_unselect_ref_head(struct btrfs_delayed_ref_root *delayed_refs,
406			     struct btrfs_delayed_ref_head *head);
407struct btrfs_delayed_ref_node *btrfs_select_delayed_ref(struct btrfs_delayed_ref_head *head);
408
409int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info, u64 seq);
410
411void btrfs_delayed_refs_rsv_release(struct btrfs_fs_info *fs_info, int nr_refs, int nr_csums);
412void btrfs_update_delayed_refs_rsv(struct btrfs_trans_handle *trans);
413void btrfs_inc_delayed_refs_rsv_bg_inserts(struct btrfs_fs_info *fs_info);
414void btrfs_dec_delayed_refs_rsv_bg_inserts(struct btrfs_fs_info *fs_info);
415void btrfs_inc_delayed_refs_rsv_bg_updates(struct btrfs_fs_info *fs_info);
416void btrfs_dec_delayed_refs_rsv_bg_updates(struct btrfs_fs_info *fs_info);
417int btrfs_delayed_refs_rsv_refill(struct btrfs_fs_info *fs_info,
418				  enum btrfs_reserve_flush_enum flush);
419bool btrfs_check_space_for_delayed_refs(struct btrfs_fs_info *fs_info);
420bool btrfs_find_delayed_tree_ref(struct btrfs_delayed_ref_head *head,
421				 u64 root, u64 parent);
422void btrfs_destroy_delayed_refs(struct btrfs_transaction *trans);
423
424static inline u64 btrfs_delayed_ref_owner(const struct btrfs_delayed_ref_node *node)
425{
426	if (node->type == BTRFS_EXTENT_DATA_REF_KEY ||
427	    node->type == BTRFS_SHARED_DATA_REF_KEY)
428		return node->data_ref.objectid;
429	return node->tree_ref.level;
430}
431
432static inline u64 btrfs_delayed_ref_offset(const struct btrfs_delayed_ref_node *node)
433{
434	if (node->type == BTRFS_EXTENT_DATA_REF_KEY ||
435	    node->type == BTRFS_SHARED_DATA_REF_KEY)
436		return node->data_ref.offset;
437	return 0;
438}
439
440static inline u8 btrfs_ref_type(const struct btrfs_ref *ref)
441{
442	ASSERT(ref->type == BTRFS_REF_DATA || ref->type == BTRFS_REF_METADATA);
443
444	if (ref->type == BTRFS_REF_DATA) {
445		if (ref->parent)
446			return BTRFS_SHARED_DATA_REF_KEY;
447		else
448			return BTRFS_EXTENT_DATA_REF_KEY;
449	} else {
450		if (ref->parent)
451			return BTRFS_SHARED_BLOCK_REF_KEY;
452		else
453			return BTRFS_TREE_BLOCK_REF_KEY;
454	}
455
456	return 0;
457}
458
459#endif