xref: /illumos-gate/usr/src/uts/common/fs/zfs/sys/dbuf.h (revision 9e3493cb)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 /*
22  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
23  * Copyright (c) 2012, 2018 by Delphix. All rights reserved.
24  * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
25  * Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
26  */
27 
28 #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 #include <sys/multilist.h>
40 
41 #ifdef	__cplusplus
42 extern "C" {
43 #endif
44 
45 #define	IN_DMU_SYNC 2
46 
47 /*
48  * define flags for dbuf_read
49  */
50 
51 #define	DB_RF_MUST_SUCCEED	(1 << 0)
52 #define	DB_RF_CANFAIL		(1 << 1)
53 #define	DB_RF_HAVESTRUCT	(1 << 2)
54 #define	DB_RF_NOPREFETCH	(1 << 3)
55 #define	DB_RF_NEVERWAIT		(1 << 4)
56 #define	DB_RF_CACHED		(1 << 5)
57 #define	DB_RF_NO_DECRYPT	(1 << 6)
58 
59 /*
60  * The simplified state transition diagram for dbufs looks like:
61  *
62  *		+----> READ ----+
63  *		|		|
64  *		|		V
65  *  (alloc)-->UNCACHED	     CACHED-->EVICTING-->(free)
66  *		|		^	 ^
67  *		|		|	 |
68  *		+----> FILL ----+	 |
69  *		|			 |
70  *		|			 |
71  *		+--------> NOFILL -------+
72  *
73  * DB_SEARCH is an invalid state for a dbuf. It is used by dbuf_free_range
74  * to find all dbufs in a range of a dnode and must be less than any other
75  * dbuf_states_t (see comment on dn_dbufs in dnode.h).
76  */
77 typedef enum dbuf_states {
78 	DB_SEARCH = -1,
79 	DB_UNCACHED,
80 	DB_FILL,
81 	DB_NOFILL,
82 	DB_READ,
83 	DB_CACHED,
84 	DB_EVICTING
85 } dbuf_states_t;
86 
87 typedef enum dbuf_cached_state {
88 	DB_NO_CACHE = -1,
89 	DB_DBUF_CACHE,
90 	DB_DBUF_METADATA_CACHE,
91 	DB_CACHE_MAX
92 } dbuf_cached_state_t;
93 
94 struct dnode;
95 struct dmu_tx;
96 
97 /*
98  * level = 0 means the user data
99  * level = 1 means the single indirect block
100  * etc.
101  */
102 
103 struct dmu_buf_impl;
104 
105 typedef enum override_states {
106 	DR_NOT_OVERRIDDEN,
107 	DR_IN_DMU_SYNC,
108 	DR_OVERRIDDEN
109 } override_states_t;
110 
111 typedef enum db_lock_type {
112 	DLT_NONE,
113 	DLT_PARENT,
114 	DLT_OBJSET
115 } db_lock_type_t;
116 
117 typedef struct dbuf_dirty_record {
118 	/* link on our parents dirty list */
119 	list_node_t dr_dirty_node;
120 
121 	/* transaction group this data will sync in */
122 	uint64_t dr_txg;
123 
124 	/* zio of outstanding write IO */
125 	zio_t *dr_zio;
126 
127 	/* pointer back to our dbuf */
128 	struct dmu_buf_impl *dr_dbuf;
129 
130 	/* pointer to next dirty record */
131 	struct dbuf_dirty_record *dr_next;
132 
133 	/* pointer to parent dirty record */
134 	struct dbuf_dirty_record *dr_parent;
135 
136 	/* How much space was changed to dsl_pool_dirty_space() for this? */
137 	unsigned int dr_accounted;
138 
139 	/* A copy of the bp that points to us */
140 	blkptr_t dr_bp_copy;
141 
142 	union dirty_types {
143 		struct dirty_indirect {
144 
145 			/* protect access to list */
146 			kmutex_t dr_mtx;
147 
148 			/* Our list of dirty children */
149 			list_t dr_children;
150 		} di;
151 		struct dirty_leaf {
152 
153 			/*
154 			 * dr_data is set when we dirty the buffer
155 			 * so that we can retain the pointer even if it
156 			 * gets COW'd in a subsequent transaction group.
157 			 */
158 			arc_buf_t *dr_data;
159 			blkptr_t dr_overridden_by;
160 			override_states_t dr_override_state;
161 			uint8_t dr_copies;
162 			boolean_t dr_nopwrite;
163 			boolean_t dr_has_raw_params;
164 
165 			/*
166 			 * If dr_has_raw_params is set, the following crypt
167 			 * params will be set on the BP that's written.
168 			 */
169 			boolean_t dr_byteorder;
170 			uint8_t	dr_salt[ZIO_DATA_SALT_LEN];
171 			uint8_t	dr_iv[ZIO_DATA_IV_LEN];
172 			uint8_t	dr_mac[ZIO_DATA_MAC_LEN];
173 		} dl;
174 	} dt;
175 } dbuf_dirty_record_t;
176 
177 typedef struct dmu_buf_impl {
178 	/*
179 	 * The following members are immutable, with the exception of
180 	 * db.db_data, which is protected by db_mtx.
181 	 */
182 
183 	/* the publicly visible structure */
184 	dmu_buf_t db;
185 
186 	/* the objset we belong to */
187 	struct objset *db_objset;
188 
189 	/*
190 	 * handle to safely access the dnode we belong to (NULL when evicted)
191 	 */
192 	struct dnode_handle *db_dnode_handle;
193 
194 	/*
195 	 * our parent buffer; if the dnode points to us directly,
196 	 * db_parent == db_dnode_handle->dnh_dnode->dn_dbuf
197 	 * only accessed by sync thread ???
198 	 * (NULL when evicted)
199 	 * May change from NULL to non-NULL under the protection of db_mtx
200 	 * (see dbuf_check_blkptr())
201 	 */
202 	struct dmu_buf_impl *db_parent;
203 
204 	/*
205 	 * link for hash table of all dmu_buf_impl_t's
206 	 */
207 	struct dmu_buf_impl *db_hash_next;
208 
209 	/* our block number */
210 	uint64_t db_blkid;
211 
212 	/*
213 	 * Pointer to the blkptr_t which points to us. May be NULL if we
214 	 * don't have one yet. (NULL when evicted)
215 	 */
216 	blkptr_t *db_blkptr;
217 
218 	/*
219 	 * Our indirection level.  Data buffers have db_level==0.
220 	 * Indirect buffers which point to data buffers have
221 	 * db_level==1. etc.  Buffers which contain dnodes have
222 	 * db_level==0, since the dnodes are stored in a file.
223 	 */
224 	uint8_t db_level;
225 
226 	/*
227 	 * Protects db_buf's contents if they contain an indirect block or data
228 	 * block of the meta-dnode. We use this lock to protect the structure of
229 	 * the block tree. This means that when modifying this dbuf's data, we
230 	 * grab its rwlock. When modifying its parent's data (including the
231 	 * blkptr to this dbuf), we grab the parent's rwlock. The lock ordering
232 	 * for this lock is:
233 	 * 1) dn_struct_rwlock
234 	 * 2) db_rwlock
235 	 * We don't currently grab multiple dbufs' db_rwlocks at once.
236 	 */
237 	krwlock_t db_rwlock;
238 
239 	/* buffer holding our data */
240 	arc_buf_t *db_buf;
241 
242 	/* db_mtx protects the members below */
243 	kmutex_t db_mtx;
244 
245 	/*
246 	 * Current state of the buffer
247 	 */
248 	dbuf_states_t db_state;
249 
250 	/*
251 	 * Refcount accessed by dmu_buf_{hold,rele}.
252 	 * If nonzero, the buffer can't be destroyed.
253 	 * Protected by db_mtx.
254 	 */
255 	zfs_refcount_t db_holds;
256 
257 	kcondvar_t db_changed;
258 	dbuf_dirty_record_t *db_data_pending;
259 
260 	/* pointer to most recent dirty record for this buffer */
261 	dbuf_dirty_record_t *db_last_dirty;
262 
263 	/*
264 	 * Our link on the owner dnodes's dn_dbufs list.
265 	 * Protected by its dn_dbufs_mtx.
266 	 */
267 	avl_node_t db_link;
268 
269 	/* Link in dbuf_cache or dbuf_metadata_cache */
270 	multilist_node_t db_cache_link;
271 
272 	/* Tells us which dbuf cache this dbuf is in, if any */
273 	dbuf_cached_state_t db_caching_status;
274 
275 	/* Data which is unique to data (leaf) blocks: */
276 
277 	/* User callback information. */
278 	dmu_buf_user_t *db_user;
279 
280 	/*
281 	 * Evict user data as soon as the dirty and reference
282 	 * counts are equal.
283 	 */
284 	uint8_t db_user_immediate_evict;
285 
286 	/*
287 	 * This block was freed while a read or write was
288 	 * active.
289 	 */
290 	uint8_t db_freed_in_flight;
291 
292 	/*
293 	 * dnode_evict_dbufs() or dnode_evict_bonus() tried to
294 	 * evict this dbuf, but couldn't due to outstanding
295 	 * references.  Evict once the refcount drops to 0.
296 	 */
297 	uint8_t db_pending_evict;
298 
299 	uint8_t db_dirtycnt;
300 } dmu_buf_impl_t;
301 
302 /* Note: the dbuf hash table is exposed only for the mdb module */
303 #define	DBUF_MUTEXES 256
304 #define	DBUF_HASH_MUTEX(h, idx) (&(h)->hash_mutexes[(idx) & (DBUF_MUTEXES-1)])
305 typedef struct dbuf_hash_table {
306 	uint64_t hash_table_mask;
307 	dmu_buf_impl_t **hash_table;
308 	kmutex_t hash_mutexes[DBUF_MUTEXES];
309 } dbuf_hash_table_t;
310 
311 typedef void (*dbuf_prefetch_fn)(void *, boolean_t);
312 
313 uint64_t dbuf_whichblock(struct dnode *di, int64_t level, uint64_t offset);
314 
315 dmu_buf_impl_t *dbuf_create_tlib(struct dnode *dn, char *data);
316 void dbuf_create_bonus(struct dnode *dn);
317 int dbuf_spill_set_blksz(dmu_buf_t *db, uint64_t blksz, dmu_tx_t *tx);
318 void dbuf_spill_hold(struct dnode *dn, dmu_buf_impl_t **dbp, void *tag);
319 
320 void dbuf_rm_spill(struct dnode *dn, dmu_tx_t *tx);
321 
322 dmu_buf_impl_t *dbuf_hold(struct dnode *dn, uint64_t blkid, void *tag);
323 dmu_buf_impl_t *dbuf_hold_level(struct dnode *dn, int level, uint64_t blkid,
324     void *tag);
325 int dbuf_hold_impl(struct dnode *dn, uint8_t level, uint64_t blkid,
326     boolean_t fail_sparse, boolean_t fail_uncached,
327     void *tag, dmu_buf_impl_t **dbp);
328 
329 int dbuf_prefetch_impl(struct dnode *dn, int64_t level, uint64_t blkid,
330     zio_priority_t prio, arc_flags_t aflags, dbuf_prefetch_fn cb,
331     void *arg);
332 int dbuf_prefetch(struct dnode *dn, int64_t level, uint64_t blkid,
333     zio_priority_t prio, arc_flags_t aflags);
334 
335 void dbuf_add_ref(dmu_buf_impl_t *db, void *tag);
336 boolean_t dbuf_try_add_ref(dmu_buf_t *db, objset_t *os, uint64_t obj,
337     uint64_t blkid, void *tag);
338 uint64_t dbuf_refcount(dmu_buf_impl_t *db);
339 
340 void dbuf_rele(dmu_buf_impl_t *db, void *tag);
341 void dbuf_rele_and_unlock(dmu_buf_impl_t *db, void *tag, boolean_t evicting);
342 
343 dmu_buf_impl_t *dbuf_find(struct objset *os, uint64_t object, uint8_t level,
344     uint64_t blkid);
345 
346 int dbuf_read(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags);
347 void dmu_buf_will_not_fill(dmu_buf_t *db, dmu_tx_t *tx);
348 void dmu_buf_will_fill(dmu_buf_t *db, dmu_tx_t *tx);
349 void dmu_buf_fill_done(dmu_buf_t *db, dmu_tx_t *tx);
350 void dbuf_assign_arcbuf(dmu_buf_impl_t *db, arc_buf_t *buf, dmu_tx_t *tx);
351 dbuf_dirty_record_t *dbuf_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx);
352 arc_buf_t *dbuf_loan_arcbuf(dmu_buf_impl_t *db);
353 void dmu_buf_write_embedded(dmu_buf_t *dbuf, void *data,
354     bp_embedded_type_t etype, enum zio_compress comp,
355     int uncompressed_size, int compressed_size, int byteorder, dmu_tx_t *tx);
356 
357 void dbuf_destroy(dmu_buf_impl_t *db);
358 
359 void dbuf_setdirty(dmu_buf_impl_t *db, dmu_tx_t *tx);
360 void dbuf_unoverride(dbuf_dirty_record_t *dr);
361 void dbuf_sync_list(list_t *list, int level, dmu_tx_t *tx);
362 void dbuf_release_bp(dmu_buf_impl_t *db);
363 db_lock_type_t dmu_buf_lock_parent(dmu_buf_impl_t *db, krw_t rw, void *tag);
364 void dmu_buf_unlock_parent(dmu_buf_impl_t *db, db_lock_type_t type, void *tag);
365 
366 boolean_t dbuf_can_remap(const dmu_buf_impl_t *buf);
367 
368 void dbuf_free_range(struct dnode *dn, uint64_t start, uint64_t end,
369     struct dmu_tx *);
370 
371 void dbuf_new_size(dmu_buf_impl_t *db, int size, dmu_tx_t *tx);
372 
373 #define	DB_DNODE(_db)		((_db)->db_dnode_handle->dnh_dnode)
374 #define	DB_DNODE_LOCK(_db)	((_db)->db_dnode_handle->dnh_zrlock)
375 #define	DB_DNODE_ENTER(_db)	(zrl_add(&DB_DNODE_LOCK(_db)))
376 #define	DB_DNODE_EXIT(_db)	(zrl_remove(&DB_DNODE_LOCK(_db)))
377 #define	DB_DNODE_HELD(_db)	(!zrl_is_zero(&DB_DNODE_LOCK(_db)))
378 
379 void dbuf_init(void);
380 void dbuf_fini(void);
381 
382 boolean_t dbuf_is_metadata(dmu_buf_impl_t *db);
383 
384 #define	DBUF_GET_BUFC_TYPE(_db)	\
385 	(dbuf_is_metadata(_db) ? ARC_BUFC_METADATA : ARC_BUFC_DATA)
386 
387 #define	DBUF_IS_CACHEABLE(_db)						\
388 	((_db)->db_objset->os_primary_cache == ZFS_CACHE_ALL ||		\
389 	(dbuf_is_metadata(_db) &&					\
390 	((_db)->db_objset->os_primary_cache == ZFS_CACHE_METADATA)))
391 
392 #define	DBUF_IS_L2CACHEABLE(_db)					\
393 	((_db)->db_objset->os_secondary_cache == ZFS_CACHE_ALL ||	\
394 	(dbuf_is_metadata(_db) &&					\
395 	((_db)->db_objset->os_secondary_cache == ZFS_CACHE_METADATA)))
396 
397 #define	DNODE_LEVEL_IS_L2CACHEABLE(_dn, _level)				\
398 	((_dn)->dn_objset->os_secondary_cache == ZFS_CACHE_ALL ||	\
399 	(((_level) > 0 ||						\
400 	DMU_OT_IS_METADATA((_dn)->dn_handle->dnh_dnode->dn_type)) &&	\
401 	((_dn)->dn_objset->os_secondary_cache == ZFS_CACHE_METADATA)))
402 
403 #ifdef ZFS_DEBUG
404 
405 /*
406  * There should be a ## between the string literal and fmt, to make it
407  * clear that we're joining two strings together, but gcc does not
408  * support that preprocessor token.
409  */
410 #define	dprintf_dbuf(dbuf, fmt, ...) do { \
411 	if (zfs_flags & ZFS_DEBUG_DPRINTF) { \
412 	char __db_buf[32]; \
413 	uint64_t __db_obj = (dbuf)->db.db_object; \
414 	if (__db_obj == DMU_META_DNODE_OBJECT) \
415 		(void) strcpy(__db_buf, "mdn"); \
416 	else \
417 		(void) snprintf(__db_buf, sizeof (__db_buf), "%lld", \
418 		    (u_longlong_t)__db_obj); \
419 	dprintf_ds((dbuf)->db_objset->os_dsl_dataset, \
420 	    "obj=%s lvl=%u blkid=%lld " fmt, \
421 	    __db_buf, (dbuf)->db_level, \
422 	    (u_longlong_t)(dbuf)->db_blkid, __VA_ARGS__); \
423 	} \
424 _NOTE(CONSTCOND) } while (0)
425 
426 #define	dprintf_dbuf_bp(db, bp, fmt, ...) do {			\
427 	if (zfs_flags & ZFS_DEBUG_DPRINTF) {			\
428 	char *__blkbuf = kmem_alloc(BP_SPRINTF_LEN, KM_SLEEP);	\
429 	snprintf_blkptr(__blkbuf, BP_SPRINTF_LEN, bp);		\
430 	dprintf_dbuf(db, fmt " %s\n", __VA_ARGS__, __blkbuf);	\
431 	kmem_free(__blkbuf, BP_SPRINTF_LEN);			\
432 	}							\
433 _NOTE(CONSTCOND) } while (0)
434 
435 #define	DBUF_VERIFY(db)	dbuf_verify(db)
436 
437 #else
438 
439 #define	dprintf_dbuf(db, fmt, ...)
440 #define	dprintf_dbuf_bp(db, bp, fmt, ...)
441 #define	DBUF_VERIFY(db)
442 
443 #endif
444 
445 
446 #ifdef	__cplusplus
447 }
448 #endif
449 
450 #endif /* _SYS_DBUF_H */
451