xref: /illumos-gate/usr/src/uts/common/fs/zfs/sys/dbuf.h (revision f985abb4a2473d3c04b086f7c9fab177e368ffef)
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, 2014 by Delphix. All rights reserved.
24  * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
25  */
26 
27 #ifndef	_SYS_DBUF_H
28 #define	_SYS_DBUF_H
29 
30 #include <sys/dmu.h>
31 #include <sys/spa.h>
32 #include <sys/txg.h>
33 #include <sys/zio.h>
34 #include <sys/arc.h>
35 #include <sys/zfs_context.h>
36 #include <sys/refcount.h>
37 #include <sys/zrlock.h>
38 
39 #ifdef	__cplusplus
40 extern "C" {
41 #endif
42 
43 #define	IN_DMU_SYNC 2
44 
45 /*
46  * define flags for dbuf_read
47  */
48 
49 #define	DB_RF_MUST_SUCCEED	(1 << 0)
50 #define	DB_RF_CANFAIL		(1 << 1)
51 #define	DB_RF_HAVESTRUCT	(1 << 2)
52 #define	DB_RF_NOPREFETCH	(1 << 3)
53 #define	DB_RF_NEVERWAIT		(1 << 4)
54 #define	DB_RF_CACHED		(1 << 5)
55 
56 /*
57  * The simplified state transition diagram for dbufs looks like:
58  *
59  *		+----> READ ----+
60  *		|		|
61  *		|		V
62  *  (alloc)-->UNCACHED	     CACHED-->EVICTING-->(free)
63  *		|		^	 ^
64  *		|		|	 |
65  *		+----> FILL ----+	 |
66  *		|			 |
67  *		|			 |
68  *		+--------> NOFILL -------+
69  *
70  * DB_SEARCH is an invalid state for a dbuf. It is used by dbuf_free_range
71  * to find all dbufs in a range of a dnode and must be less than any other
72  * dbuf_states_t (see comment on dn_dbufs in dnode.h).
73  */
74 typedef enum dbuf_states {
75 	DB_SEARCH = -1,
76 	DB_UNCACHED,
77 	DB_FILL,
78 	DB_NOFILL,
79 	DB_READ,
80 	DB_CACHED,
81 	DB_EVICTING
82 } dbuf_states_t;
83 
84 struct dnode;
85 struct dmu_tx;
86 
87 /*
88  * level = 0 means the user data
89  * level = 1 means the single indirect block
90  * etc.
91  */
92 
93 struct dmu_buf_impl;
94 
95 typedef enum override_states {
96 	DR_NOT_OVERRIDDEN,
97 	DR_IN_DMU_SYNC,
98 	DR_OVERRIDDEN
99 } override_states_t;
100 
101 typedef struct dbuf_dirty_record {
102 	/* link on our parents dirty list */
103 	list_node_t dr_dirty_node;
104 
105 	/* transaction group this data will sync in */
106 	uint64_t dr_txg;
107 
108 	/* zio of outstanding write IO */
109 	zio_t *dr_zio;
110 
111 	/* pointer back to our dbuf */
112 	struct dmu_buf_impl *dr_dbuf;
113 
114 	/* pointer to next dirty record */
115 	struct dbuf_dirty_record *dr_next;
116 
117 	/* pointer to parent dirty record */
118 	struct dbuf_dirty_record *dr_parent;
119 
120 	/* How much space was changed to dsl_pool_dirty_space() for this? */
121 	unsigned int dr_accounted;
122 
123 	union dirty_types {
124 		struct dirty_indirect {
125 
126 			/* protect access to list */
127 			kmutex_t dr_mtx;
128 
129 			/* Our list of dirty children */
130 			list_t dr_children;
131 		} di;
132 		struct dirty_leaf {
133 
134 			/*
135 			 * dr_data is set when we dirty the buffer
136 			 * so that we can retain the pointer even if it
137 			 * gets COW'd in a subsequent transaction group.
138 			 */
139 			arc_buf_t *dr_data;
140 			blkptr_t dr_overridden_by;
141 			override_states_t dr_override_state;
142 			uint8_t dr_copies;
143 			boolean_t dr_nopwrite;
144 		} dl;
145 	} dt;
146 } dbuf_dirty_record_t;
147 
148 typedef struct dmu_buf_impl {
149 	/*
150 	 * The following members are immutable, with the exception of
151 	 * db.db_data, which is protected by db_mtx.
152 	 */
153 
154 	/* the publicly visible structure */
155 	dmu_buf_t db;
156 
157 	/* the objset we belong to */
158 	struct objset *db_objset;
159 
160 	/*
161 	 * handle to safely access the dnode we belong to (NULL when evicted)
162 	 */
163 	struct dnode_handle *db_dnode_handle;
164 
165 	/*
166 	 * our parent buffer; if the dnode points to us directly,
167 	 * db_parent == db_dnode_handle->dnh_dnode->dn_dbuf
168 	 * only accessed by sync thread ???
169 	 * (NULL when evicted)
170 	 * May change from NULL to non-NULL under the protection of db_mtx
171 	 * (see dbuf_check_blkptr())
172 	 */
173 	struct dmu_buf_impl *db_parent;
174 
175 	/*
176 	 * link for hash table of all dmu_buf_impl_t's
177 	 */
178 	struct dmu_buf_impl *db_hash_next;
179 
180 	/* our block number */
181 	uint64_t db_blkid;
182 
183 	/*
184 	 * Pointer to the blkptr_t which points to us. May be NULL if we
185 	 * don't have one yet. (NULL when evicted)
186 	 */
187 	blkptr_t *db_blkptr;
188 
189 	/*
190 	 * Our indirection level.  Data buffers have db_level==0.
191 	 * Indirect buffers which point to data buffers have
192 	 * db_level==1. etc.  Buffers which contain dnodes have
193 	 * db_level==0, since the dnodes are stored in a file.
194 	 */
195 	uint8_t db_level;
196 
197 	/* db_mtx protects the members below */
198 	kmutex_t db_mtx;
199 
200 	/*
201 	 * Current state of the buffer
202 	 */
203 	dbuf_states_t db_state;
204 
205 	/*
206 	 * Refcount accessed by dmu_buf_{hold,rele}.
207 	 * If nonzero, the buffer can't be destroyed.
208 	 * Protected by db_mtx.
209 	 */
210 	refcount_t db_holds;
211 
212 	/* buffer holding our data */
213 	arc_buf_t *db_buf;
214 
215 	kcondvar_t db_changed;
216 	dbuf_dirty_record_t *db_data_pending;
217 
218 	/* pointer to most recent dirty record for this buffer */
219 	dbuf_dirty_record_t *db_last_dirty;
220 
221 	/*
222 	 * Our link on the owner dnodes's dn_dbufs list.
223 	 * Protected by its dn_dbufs_mtx.
224 	 */
225 	avl_node_t db_link;
226 
227 	/* Data which is unique to data (leaf) blocks: */
228 
229 	/* stuff we store for the user (see dmu_buf_set_user) */
230 	void *db_user_ptr;
231 	void **db_user_data_ptr_ptr;
232 	dmu_buf_evict_func_t *db_evict_func;
233 
234 	uint8_t db_immediate_evict;
235 	uint8_t db_freed_in_flight;
236 
237 	uint8_t db_dirtycnt;
238 } dmu_buf_impl_t;
239 
240 /* Note: the dbuf hash table is exposed only for the mdb module */
241 #define	DBUF_MUTEXES 256
242 #define	DBUF_HASH_MUTEX(h, idx) (&(h)->hash_mutexes[(idx) & (DBUF_MUTEXES-1)])
243 typedef struct dbuf_hash_table {
244 	uint64_t hash_table_mask;
245 	dmu_buf_impl_t **hash_table;
246 	kmutex_t hash_mutexes[DBUF_MUTEXES];
247 } dbuf_hash_table_t;
248 
249 
250 uint64_t dbuf_whichblock(struct dnode *di, uint64_t offset);
251 
252 dmu_buf_impl_t *dbuf_create_tlib(struct dnode *dn, char *data);
253 void dbuf_create_bonus(struct dnode *dn);
254 int dbuf_spill_set_blksz(dmu_buf_t *db, uint64_t blksz, dmu_tx_t *tx);
255 void dbuf_spill_hold(struct dnode *dn, dmu_buf_impl_t **dbp, void *tag);
256 
257 void dbuf_rm_spill(struct dnode *dn, dmu_tx_t *tx);
258 
259 dmu_buf_impl_t *dbuf_hold(struct dnode *dn, uint64_t blkid, void *tag);
260 dmu_buf_impl_t *dbuf_hold_level(struct dnode *dn, int level, uint64_t blkid,
261     void *tag);
262 int dbuf_hold_impl(struct dnode *dn, uint8_t level, uint64_t blkid, int create,
263     void *tag, dmu_buf_impl_t **dbp);
264 
265 void dbuf_prefetch(struct dnode *dn, uint64_t blkid, zio_priority_t prio);
266 
267 void dbuf_add_ref(dmu_buf_impl_t *db, void *tag);
268 uint64_t dbuf_refcount(dmu_buf_impl_t *db);
269 
270 void dbuf_rele(dmu_buf_impl_t *db, void *tag);
271 void dbuf_rele_and_unlock(dmu_buf_impl_t *db, void *tag);
272 
273 dmu_buf_impl_t *dbuf_find(struct dnode *dn, uint8_t level, uint64_t blkid);
274 
275 int dbuf_read(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags);
276 void dmu_buf_will_not_fill(dmu_buf_t *db, dmu_tx_t *tx);
277 void dmu_buf_will_fill(dmu_buf_t *db, dmu_tx_t *tx);
278 void dmu_buf_fill_done(dmu_buf_t *db, dmu_tx_t *tx);
279 void dbuf_assign_arcbuf(dmu_buf_impl_t *db, arc_buf_t *buf, dmu_tx_t *tx);
280 dbuf_dirty_record_t *dbuf_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx);
281 arc_buf_t *dbuf_loan_arcbuf(dmu_buf_impl_t *db);
282 void dmu_buf_write_embedded(dmu_buf_t *dbuf, void *data,
283     bp_embedded_type_t etype, enum zio_compress comp,
284     int uncompressed_size, int compressed_size, int byteorder, dmu_tx_t *tx);
285 
286 void dbuf_clear(dmu_buf_impl_t *db);
287 void dbuf_evict(dmu_buf_impl_t *db);
288 
289 void dbuf_setdirty(dmu_buf_impl_t *db, dmu_tx_t *tx);
290 void dbuf_unoverride(dbuf_dirty_record_t *dr);
291 void dbuf_sync_list(list_t *list, dmu_tx_t *tx);
292 void dbuf_release_bp(dmu_buf_impl_t *db);
293 
294 void dbuf_free_range(struct dnode *dn, uint64_t start, uint64_t end,
295     struct dmu_tx *);
296 
297 void dbuf_new_size(dmu_buf_impl_t *db, int size, dmu_tx_t *tx);
298 
299 #define	DB_DNODE(_db)		((_db)->db_dnode_handle->dnh_dnode)
300 #define	DB_DNODE_LOCK(_db)	((_db)->db_dnode_handle->dnh_zrlock)
301 #define	DB_DNODE_ENTER(_db)	(zrl_add(&DB_DNODE_LOCK(_db)))
302 #define	DB_DNODE_EXIT(_db)	(zrl_remove(&DB_DNODE_LOCK(_db)))
303 #define	DB_DNODE_HELD(_db)	(!zrl_is_zero(&DB_DNODE_LOCK(_db)))
304 
305 void dbuf_init(void);
306 void dbuf_fini(void);
307 
308 boolean_t dbuf_is_metadata(dmu_buf_impl_t *db);
309 
310 #define	DBUF_GET_BUFC_TYPE(_db)	\
311 	(dbuf_is_metadata(_db) ? ARC_BUFC_METADATA : ARC_BUFC_DATA)
312 
313 #define	DBUF_IS_CACHEABLE(_db)						\
314 	((_db)->db_objset->os_primary_cache == ZFS_CACHE_ALL ||		\
315 	(dbuf_is_metadata(_db) &&					\
316 	((_db)->db_objset->os_primary_cache == ZFS_CACHE_METADATA)))
317 
318 #define	DBUF_IS_L2CACHEABLE(_db)					\
319 	((_db)->db_objset->os_secondary_cache == ZFS_CACHE_ALL ||	\
320 	(dbuf_is_metadata(_db) &&					\
321 	((_db)->db_objset->os_secondary_cache == ZFS_CACHE_METADATA)))
322 
323 #define	DBUF_IS_L2COMPRESSIBLE(_db)					\
324 	((_db)->db_objset->os_compress != ZIO_COMPRESS_OFF ||		\
325 	(dbuf_is_metadata(_db) && zfs_mdcomp_disable == B_FALSE))
326 
327 #ifdef ZFS_DEBUG
328 
329 /*
330  * There should be a ## between the string literal and fmt, to make it
331  * clear that we're joining two strings together, but gcc does not
332  * support that preprocessor token.
333  */
334 #define	dprintf_dbuf(dbuf, fmt, ...) do { \
335 	if (zfs_flags & ZFS_DEBUG_DPRINTF) { \
336 	char __db_buf[32]; \
337 	uint64_t __db_obj = (dbuf)->db.db_object; \
338 	if (__db_obj == DMU_META_DNODE_OBJECT) \
339 		(void) strcpy(__db_buf, "mdn"); \
340 	else \
341 		(void) snprintf(__db_buf, sizeof (__db_buf), "%lld", \
342 		    (u_longlong_t)__db_obj); \
343 	dprintf_ds((dbuf)->db_objset->os_dsl_dataset, \
344 	    "obj=%s lvl=%u blkid=%lld " fmt, \
345 	    __db_buf, (dbuf)->db_level, \
346 	    (u_longlong_t)(dbuf)->db_blkid, __VA_ARGS__); \
347 	} \
348 _NOTE(CONSTCOND) } while (0)
349 
350 #define	dprintf_dbuf_bp(db, bp, fmt, ...) do {			\
351 	if (zfs_flags & ZFS_DEBUG_DPRINTF) {			\
352 	char *__blkbuf = kmem_alloc(BP_SPRINTF_LEN, KM_SLEEP);	\
353 	snprintf_blkptr(__blkbuf, BP_SPRINTF_LEN, bp);		\
354 	dprintf_dbuf(db, fmt " %s\n", __VA_ARGS__, __blkbuf);	\
355 	kmem_free(__blkbuf, BP_SPRINTF_LEN);			\
356 	}							\
357 _NOTE(CONSTCOND) } while (0)
358 
359 #define	DBUF_VERIFY(db)	dbuf_verify(db)
360 
361 #else
362 
363 #define	dprintf_dbuf(db, fmt, ...)
364 #define	dprintf_dbuf_bp(db, bp, fmt, ...)
365 #define	DBUF_VERIFY(db)
366 
367 #endif
368 
369 
370 #ifdef	__cplusplus
371 }
372 #endif
373 
374 #endif /* _SYS_DBUF_H */
375