dbuf.h revision 304136
1258283Speter/*
2258283Speter * CDDL HEADER START
3258283Speter *
4258283Speter * The contents of this file are subject to the terms of the
5258283Speter * Common Development and Distribution License (the "License").
6258283Speter * You may not use this file except in compliance with the License.
7258283Speter *
8258283Speter * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9313594Sngie * or http://www.opensolaris.org/os/licensing.
10258283Speter * See the License for the specific language governing permissions
11258283Speter * and limitations under the License.
12258283Speter *
13258283Speter * When distributing Covered Code, include this CDDL HEADER in each
14258283Speter * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15258750Sgjb * If applicable, add the following below this CDDL HEADER, with the
16258750Sgjb * fields enclosed by brackets "[]" replaced with your own identifying
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18258283Speter *
19258283Speter * CDDL HEADER END
20258283Speter */
21313594Sngie/*
22258750Sgjb * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
23313594Sngie * Copyright (c) 2012, 2015 by Delphix. All rights reserved.
24258283Speter * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
25258283Speter * Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
26258750Sgjb */
27258750Sgjb
28258283Speter#ifndef	_SYS_DBUF_H
29#define	_SYS_DBUF_H
30
31#include <sys/dmu.h>
32#include <sys/spa.h>
33#include <sys/txg.h>
34#include <sys/zio.h>
35#include <sys/arc.h>
36#include <sys/zfs_context.h>
37#include <sys/refcount.h>
38#include <sys/zrlock.h>
39
40#ifdef	__cplusplus
41extern "C" {
42#endif
43
44#define	IN_DMU_SYNC 2
45
46/*
47 * define flags for dbuf_read
48 */
49
50#define	DB_RF_MUST_SUCCEED	(1 << 0)
51#define	DB_RF_CANFAIL		(1 << 1)
52#define	DB_RF_HAVESTRUCT	(1 << 2)
53#define	DB_RF_NOPREFETCH	(1 << 3)
54#define	DB_RF_NEVERWAIT		(1 << 4)
55#define	DB_RF_CACHED		(1 << 5)
56
57/*
58 * The simplified state transition diagram for dbufs looks like:
59 *
60 *		+----> READ ----+
61 *		|		|
62 *		|		V
63 *  (alloc)-->UNCACHED	     CACHED-->EVICTING-->(free)
64 *		|		^	 ^
65 *		|		|	 |
66 *		+----> FILL ----+	 |
67 *		|			 |
68 *		|			 |
69 *		+--------> NOFILL -------+
70 *
71 * DB_SEARCH is an invalid state for a dbuf. It is used by dbuf_free_range
72 * to find all dbufs in a range of a dnode and must be less than any other
73 * dbuf_states_t (see comment on dn_dbufs in dnode.h).
74 */
75typedef enum dbuf_states {
76	DB_SEARCH = -1,
77	DB_UNCACHED,
78	DB_FILL,
79	DB_NOFILL,
80	DB_READ,
81	DB_CACHED,
82	DB_EVICTING
83} dbuf_states_t;
84
85struct dnode;
86struct dmu_tx;
87
88/*
89 * level = 0 means the user data
90 * level = 1 means the single indirect block
91 * etc.
92 */
93
94struct dmu_buf_impl;
95
96typedef enum override_states {
97	DR_NOT_OVERRIDDEN,
98	DR_IN_DMU_SYNC,
99	DR_OVERRIDDEN
100} override_states_t;
101
102typedef struct dbuf_dirty_record {
103	/* link on our parents dirty list */
104	list_node_t dr_dirty_node;
105
106	/* transaction group this data will sync in */
107	uint64_t dr_txg;
108
109	/* zio of outstanding write IO */
110	zio_t *dr_zio;
111
112	/* pointer back to our dbuf */
113	struct dmu_buf_impl *dr_dbuf;
114
115	/* pointer to next dirty record */
116	struct dbuf_dirty_record *dr_next;
117
118	/* pointer to parent dirty record */
119	struct dbuf_dirty_record *dr_parent;
120
121	/* How much space was changed to dsl_pool_dirty_space() for this? */
122	unsigned int dr_accounted;
123
124	/* A copy of the bp that points to us */
125	blkptr_t dr_bp_copy;
126
127	union dirty_types {
128		struct dirty_indirect {
129
130			/* protect access to list */
131			kmutex_t dr_mtx;
132
133			/* Our list of dirty children */
134			list_t dr_children;
135		} di;
136		struct dirty_leaf {
137
138			/*
139			 * dr_data is set when we dirty the buffer
140			 * so that we can retain the pointer even if it
141			 * gets COW'd in a subsequent transaction group.
142			 */
143			arc_buf_t *dr_data;
144			blkptr_t dr_overridden_by;
145			override_states_t dr_override_state;
146			uint8_t dr_copies;
147			boolean_t dr_nopwrite;
148		} dl;
149	} dt;
150} dbuf_dirty_record_t;
151
152typedef struct dmu_buf_impl {
153	/*
154	 * The following members are immutable, with the exception of
155	 * db.db_data, which is protected by db_mtx.
156	 */
157
158	/* the publicly visible structure */
159	dmu_buf_t db;
160
161	/* the objset we belong to */
162	struct objset *db_objset;
163
164	/*
165	 * handle to safely access the dnode we belong to (NULL when evicted)
166	 */
167	struct dnode_handle *db_dnode_handle;
168
169	/*
170	 * our parent buffer; if the dnode points to us directly,
171	 * db_parent == db_dnode_handle->dnh_dnode->dn_dbuf
172	 * only accessed by sync thread ???
173	 * (NULL when evicted)
174	 * May change from NULL to non-NULL under the protection of db_mtx
175	 * (see dbuf_check_blkptr())
176	 */
177	struct dmu_buf_impl *db_parent;
178
179	/*
180	 * link for hash table of all dmu_buf_impl_t's
181	 */
182	struct dmu_buf_impl *db_hash_next;
183
184	/* our block number */
185	uint64_t db_blkid;
186
187	/*
188	 * Pointer to the blkptr_t which points to us. May be NULL if we
189	 * don't have one yet. (NULL when evicted)
190	 */
191	blkptr_t *db_blkptr;
192
193	/*
194	 * Our indirection level.  Data buffers have db_level==0.
195	 * Indirect buffers which point to data buffers have
196	 * db_level==1. etc.  Buffers which contain dnodes have
197	 * db_level==0, since the dnodes are stored in a file.
198	 */
199	uint8_t db_level;
200
201	/* db_mtx protects the members below */
202	kmutex_t db_mtx;
203
204	/*
205	 * Current state of the buffer
206	 */
207	dbuf_states_t db_state;
208
209	/*
210	 * Refcount accessed by dmu_buf_{hold,rele}.
211	 * If nonzero, the buffer can't be destroyed.
212	 * Protected by db_mtx.
213	 */
214	refcount_t db_holds;
215
216	/* buffer holding our data */
217	arc_buf_t *db_buf;
218
219	kcondvar_t db_changed;
220	dbuf_dirty_record_t *db_data_pending;
221
222	/* pointer to most recent dirty record for this buffer */
223	dbuf_dirty_record_t *db_last_dirty;
224
225	/*
226	 * Our link on the owner dnodes's dn_dbufs list.
227	 * Protected by its dn_dbufs_mtx.
228	 */
229	avl_node_t db_link;
230
231	/* Data which is unique to data (leaf) blocks: */
232
233	/* User callback information. */
234	dmu_buf_user_t *db_user;
235
236	/*
237	 * Evict user data as soon as the dirty and reference
238	 * counts are equal.
239	 */
240	uint8_t db_user_immediate_evict;
241
242	/*
243	 * This block was freed while a read or write was
244	 * active.
245	 */
246	uint8_t db_freed_in_flight;
247
248	/*
249	 * dnode_evict_dbufs() or dnode_evict_bonus() tried to
250	 * evict this dbuf, but couldn't due to outstanding
251	 * references.  Evict once the refcount drops to 0.
252	 */
253	uint8_t db_pending_evict;
254
255	uint8_t db_dirtycnt;
256} dmu_buf_impl_t;
257
258/* Note: the dbuf hash table is exposed only for the mdb module */
259#define	DBUF_MUTEXES 256
260#define	DBUF_HASH_MUTEX(h, idx) (&(h)->hash_mutexes[(idx) & (DBUF_MUTEXES-1)])
261typedef struct dbuf_hash_table {
262	uint64_t hash_table_mask;
263	dmu_buf_impl_t **hash_table;
264	kmutex_t hash_mutexes[DBUF_MUTEXES];
265} dbuf_hash_table_t;
266
267uint64_t dbuf_whichblock(struct dnode *di, int64_t level, uint64_t offset);
268
269dmu_buf_impl_t *dbuf_create_tlib(struct dnode *dn, char *data);
270void dbuf_create_bonus(struct dnode *dn);
271int dbuf_spill_set_blksz(dmu_buf_t *db, uint64_t blksz, dmu_tx_t *tx);
272void dbuf_spill_hold(struct dnode *dn, dmu_buf_impl_t **dbp, void *tag);
273
274void dbuf_rm_spill(struct dnode *dn, dmu_tx_t *tx);
275
276dmu_buf_impl_t *dbuf_hold(struct dnode *dn, uint64_t blkid, void *tag);
277dmu_buf_impl_t *dbuf_hold_level(struct dnode *dn, int level, uint64_t blkid,
278    void *tag);
279int dbuf_hold_impl(struct dnode *dn, uint8_t level, uint64_t blkid,
280    boolean_t fail_sparse, boolean_t fail_uncached,
281    void *tag, dmu_buf_impl_t **dbp);
282
283void dbuf_prefetch(struct dnode *dn, int64_t level, uint64_t blkid,
284    zio_priority_t prio, arc_flags_t aflags);
285
286void dbuf_add_ref(dmu_buf_impl_t *db, void *tag);
287boolean_t dbuf_try_add_ref(dmu_buf_t *db, objset_t *os, uint64_t obj,
288    uint64_t blkid, void *tag);
289uint64_t dbuf_refcount(dmu_buf_impl_t *db);
290
291void dbuf_rele(dmu_buf_impl_t *db, void *tag);
292void dbuf_rele_and_unlock(dmu_buf_impl_t *db, void *tag);
293
294dmu_buf_impl_t *dbuf_find(struct objset *os, uint64_t object, uint8_t level,
295    uint64_t blkid);
296
297int dbuf_read(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags);
298void dmu_buf_will_not_fill(dmu_buf_t *db, dmu_tx_t *tx);
299void dmu_buf_will_fill(dmu_buf_t *db, dmu_tx_t *tx);
300void dmu_buf_fill_done(dmu_buf_t *db, dmu_tx_t *tx);
301void dbuf_assign_arcbuf(dmu_buf_impl_t *db, arc_buf_t *buf, dmu_tx_t *tx);
302dbuf_dirty_record_t *dbuf_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx);
303arc_buf_t *dbuf_loan_arcbuf(dmu_buf_impl_t *db);
304void dmu_buf_write_embedded(dmu_buf_t *dbuf, void *data,
305    bp_embedded_type_t etype, enum zio_compress comp,
306    int uncompressed_size, int compressed_size, int byteorder, dmu_tx_t *tx);
307
308void dbuf_clear(dmu_buf_impl_t *db);
309void dbuf_evict(dmu_buf_impl_t *db);
310
311void dbuf_setdirty(dmu_buf_impl_t *db, dmu_tx_t *tx);
312void dbuf_unoverride(dbuf_dirty_record_t *dr);
313void dbuf_sync_list(list_t *list, int level, dmu_tx_t *tx);
314void dbuf_release_bp(dmu_buf_impl_t *db);
315
316void dbuf_free_range(struct dnode *dn, uint64_t start, uint64_t end,
317    struct dmu_tx *);
318
319void dbuf_new_size(dmu_buf_impl_t *db, int size, dmu_tx_t *tx);
320
321#define	DB_DNODE(_db)		((_db)->db_dnode_handle->dnh_dnode)
322#define	DB_DNODE_LOCK(_db)	((_db)->db_dnode_handle->dnh_zrlock)
323#define	DB_DNODE_ENTER(_db)	(zrl_add(&DB_DNODE_LOCK(_db)))
324#define	DB_DNODE_EXIT(_db)	(zrl_remove(&DB_DNODE_LOCK(_db)))
325#define	DB_DNODE_HELD(_db)	(!zrl_is_zero(&DB_DNODE_LOCK(_db)))
326
327void dbuf_init(void);
328void dbuf_fini(void);
329
330boolean_t dbuf_is_metadata(dmu_buf_impl_t *db);
331
332#define	DBUF_GET_BUFC_TYPE(_db)	\
333	(dbuf_is_metadata(_db) ? ARC_BUFC_METADATA : ARC_BUFC_DATA)
334
335#define	DBUF_IS_CACHEABLE(_db)						\
336	((_db)->db_objset->os_primary_cache == ZFS_CACHE_ALL ||		\
337	(dbuf_is_metadata(_db) &&					\
338	((_db)->db_objset->os_primary_cache == ZFS_CACHE_METADATA)))
339
340#define	DBUF_IS_L2CACHEABLE(_db)					\
341	((_db)->db_objset->os_secondary_cache == ZFS_CACHE_ALL ||	\
342	(dbuf_is_metadata(_db) &&					\
343	((_db)->db_objset->os_secondary_cache == ZFS_CACHE_METADATA)))
344
345#define	DBUF_IS_L2COMPRESSIBLE(_db)					\
346	((_db)->db_objset->os_compress != ZIO_COMPRESS_OFF ||		\
347	(dbuf_is_metadata(_db) && zfs_mdcomp_disable == B_FALSE))
348
349#ifdef ZFS_DEBUG
350
351/*
352 * There should be a ## between the string literal and fmt, to make it
353 * clear that we're joining two strings together, but gcc does not
354 * support that preprocessor token.
355 */
356#define	dprintf_dbuf(dbuf, fmt, ...) do { \
357	if (zfs_flags & ZFS_DEBUG_DPRINTF) { \
358	char __db_buf[32]; \
359	uint64_t __db_obj = (dbuf)->db.db_object; \
360	if (__db_obj == DMU_META_DNODE_OBJECT) \
361		(void) strcpy(__db_buf, "mdn"); \
362	else \
363		(void) snprintf(__db_buf, sizeof (__db_buf), "%lld", \
364		    (u_longlong_t)__db_obj); \
365	dprintf_ds((dbuf)->db_objset->os_dsl_dataset, \
366	    "obj=%s lvl=%u blkid=%lld " fmt, \
367	    __db_buf, (dbuf)->db_level, \
368	    (u_longlong_t)(dbuf)->db_blkid, __VA_ARGS__); \
369	} \
370_NOTE(CONSTCOND) } while (0)
371
372#define	dprintf_dbuf_bp(db, bp, fmt, ...) do {			\
373	if (zfs_flags & ZFS_DEBUG_DPRINTF) {			\
374	char *__blkbuf = kmem_alloc(BP_SPRINTF_LEN, KM_SLEEP);	\
375	snprintf_blkptr(__blkbuf, BP_SPRINTF_LEN, bp);		\
376	dprintf_dbuf(db, fmt " %s\n", __VA_ARGS__, __blkbuf);	\
377	kmem_free(__blkbuf, BP_SPRINTF_LEN);			\
378	}							\
379_NOTE(CONSTCOND) } while (0)
380
381#define	DBUF_VERIFY(db)	dbuf_verify(db)
382
383#else
384
385#define	dprintf_dbuf(db, fmt, ...)
386#define	dprintf_dbuf_bp(db, bp, fmt, ...)
387#define	DBUF_VERIFY(db)
388
389#endif
390
391
392#ifdef	__cplusplus
393}
394#endif
395
396#endif /* _SYS_DBUF_H */
397