xref: /illumos-gate/usr/src/uts/common/fs/zfs/sys/zap.h (revision 92241e0b)
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
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17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 /*
22  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
23  * Use is subject to license terms.
24  */
25 
26 #ifndef	_SYS_ZAP_H
27 #define	_SYS_ZAP_H
28 
29 /*
30  * ZAP - ZFS Attribute Processor
31  *
32  * The ZAP is a module which sits on top of the DMU (Data Management
33  * Unit) and implements a higher-level storage primitive using DMU
34  * objects.  Its primary consumer is the ZPL (ZFS Posix Layer).
35  *
36  * A "zapobj" is a DMU object which the ZAP uses to stores attributes.
37  * Users should use only zap routines to access a zapobj - they should
38  * not access the DMU object directly using DMU routines.
39  *
40  * The attributes stored in a zapobj are name-value pairs.  The name is
41  * a zero-terminated string of up to ZAP_MAXNAMELEN bytes (including
42  * terminating NULL).  The value is an array of integers, which may be
43  * 1, 2, 4, or 8 bytes long.  The total space used by the array (number
44  * of integers * integer length) can be up to ZAP_MAXVALUELEN bytes.
45  * Note that an 8-byte integer value can be used to store the location
46  * (object number) of another dmu object (which may be itself a zapobj).
47  * Note that you can use a zero-length attribute to store a single bit
48  * of information - the attribute is present or not.
49  *
50  * The ZAP routines are thread-safe.  However, you must observe the
51  * DMU's restriction that a transaction may not be operated on
52  * concurrently.
53  *
54  * Any of the routines that return an int may return an I/O error (EIO
55  * or ECHECKSUM).
56  *
57  *
58  * Implementation / Performance Notes:
59  *
60  * The ZAP is intended to operate most efficiently on attributes with
61  * short (49 bytes or less) names and single 8-byte values, for which
62  * the microzap will be used.  The ZAP should be efficient enough so
63  * that the user does not need to cache these attributes.
64  *
65  * The ZAP's locking scheme makes its routines thread-safe.  Operations
66  * on different zapobjs will be processed concurrently.  Operations on
67  * the same zapobj which only read data will be processed concurrently.
68  * Operations on the same zapobj which modify data will be processed
69  * concurrently when there are many attributes in the zapobj (because
70  * the ZAP uses per-block locking - more than 128 * (number of cpus)
71  * small attributes will suffice).
72  */
73 
74 /*
75  * We're using zero-terminated byte strings (ie. ASCII or UTF-8 C
76  * strings) for the names of attributes, rather than a byte string
77  * bounded by an explicit length.  If some day we want to support names
78  * in character sets which have embedded zeros (eg. UTF-16, UTF-32),
79  * we'll have to add routines for using length-bounded strings.
80  */
81 
82 #include <sys/dmu.h>
83 
84 #ifdef	__cplusplus
85 extern "C" {
86 #endif
87 
88 /*
89  * The matchtype specifies which entry will be accessed.
90  * MT_EXACT: only find an exact match (non-normalized)
91  * MT_FIRST: find the "first" normalized (case and Unicode
92  *     form) match; the designated "first" match will not change as long
93  *     as the set of entries with this normalization doesn't change
94  * MT_BEST: if there is an exact match, find that, otherwise find the
95  *     first normalized match
96  */
97 typedef enum matchtype
98 {
99 	MT_EXACT,
100 	MT_BEST,
101 	MT_FIRST
102 } matchtype_t;
103 
104 typedef enum zap_flags {
105 	/* Use 64-bit hash value (serialized cursors will always use 64-bits) */
106 	ZAP_FLAG_HASH64 = 1 << 0,
107 	/* Key is binary, not string (zap_add_uint64() can be used) */
108 	ZAP_FLAG_UINT64_KEY = 1 << 1,
109 	/*
110 	 * First word of key (which must be an array of uint64) is
111 	 * already randomly distributed.
112 	 */
113 	ZAP_FLAG_PRE_HASHED_KEY = 1 << 2,
114 } zap_flags_t;
115 
116 /*
117  * Create a new zapobj with no attributes and return its object number.
118  * MT_EXACT will cause the zap object to only support MT_EXACT lookups,
119  * otherwise any matchtype can be used for lookups.
120  *
121  * normflags specifies what normalization will be done.  values are:
122  * 0: no normalization (legacy on-disk format, supports MT_EXACT matching
123  *     only)
124  * U8_TEXTPREP_TOLOWER: case normalization will be performed.
125  *     MT_FIRST/MT_BEST matching will find entries that match without
126  *     regard to case (eg. looking for "foo" can find an entry "Foo").
127  * Eventually, other flags will permit unicode normalization as well.
128  */
129 uint64_t zap_create(objset_t *ds, dmu_object_type_t ot,
130     dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *tx);
131 uint64_t zap_create_norm(objset_t *ds, int normflags, dmu_object_type_t ot,
132     dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *tx);
133 uint64_t zap_create_flags(objset_t *os, int normflags, zap_flags_t flags,
134     dmu_object_type_t ot, int leaf_blockshift, int indirect_blockshift,
135     dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *tx);
136 
137 /*
138  * Create a new zapobj with no attributes from the given (unallocated)
139  * object number.
140  */
141 int zap_create_claim(objset_t *ds, uint64_t obj, dmu_object_type_t ot,
142     dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *tx);
143 int zap_create_claim_norm(objset_t *ds, uint64_t obj,
144     int normflags, dmu_object_type_t ot,
145     dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *tx);
146 
147 /*
148  * The zapobj passed in must be a valid ZAP object for all of the
149  * following routines.
150  */
151 
152 /*
153  * Destroy this zapobj and all its attributes.
154  *
155  * Frees the object number using dmu_object_free.
156  */
157 int zap_destroy(objset_t *ds, uint64_t zapobj, dmu_tx_t *tx);
158 
159 /*
160  * Manipulate attributes.
161  *
162  * 'integer_size' is in bytes, and must be 1, 2, 4, or 8.
163  */
164 
165 /*
166  * Retrieve the contents of the attribute with the given name.
167  *
168  * If the requested attribute does not exist, the call will fail and
169  * return ENOENT.
170  *
171  * If 'integer_size' is smaller than the attribute's integer size, the
172  * call will fail and return EINVAL.
173  *
174  * If 'integer_size' is equal to or larger than the attribute's integer
175  * size, the call will succeed and return 0.  * When converting to a
176  * larger integer size, the integers will be treated as unsigned (ie. no
177  * sign-extension will be performed).
178  *
179  * 'num_integers' is the length (in integers) of 'buf'.
180  *
181  * If the attribute is longer than the buffer, as many integers as will
182  * fit will be transferred to 'buf'.  If the entire attribute was not
183  * transferred, the call will return EOVERFLOW.
184  *
185  * If rn_len is nonzero, realname will be set to the name of the found
186  * entry (which may be different from the requested name if matchtype is
187  * not MT_EXACT).
188  *
189  * If normalization_conflictp is not NULL, it will be set if there is
190  * another name with the same case/unicode normalized form.
191  */
192 int zap_lookup(objset_t *ds, uint64_t zapobj, const char *name,
193     uint64_t integer_size, uint64_t num_integers, void *buf);
194 int zap_lookup_norm(objset_t *ds, uint64_t zapobj, const char *name,
195     uint64_t integer_size, uint64_t num_integers, void *buf,
196     matchtype_t mt, char *realname, int rn_len,
197     boolean_t *normalization_conflictp);
198 int zap_lookup_uint64(objset_t *os, uint64_t zapobj, const uint64_t *key,
199     int key_numints, uint64_t integer_size, uint64_t num_integers, void *buf);
200 int zap_contains(objset_t *ds, uint64_t zapobj, const char *name);
201 
202 int zap_count_write(objset_t *os, uint64_t zapobj, const char *name,
203     int add, uint64_t *towrite, uint64_t *tooverwrite);
204 
205 /*
206  * Create an attribute with the given name and value.
207  *
208  * If an attribute with the given name already exists, the call will
209  * fail and return EEXIST.
210  */
211 int zap_add(objset_t *ds, uint64_t zapobj, const char *key,
212     int integer_size, uint64_t num_integers,
213     const void *val, dmu_tx_t *tx);
214 int zap_add_uint64(objset_t *ds, uint64_t zapobj, const uint64_t *key,
215     int key_numints, int integer_size, uint64_t num_integers,
216     const void *val, dmu_tx_t *tx);
217 
218 /*
219  * Set the attribute with the given name to the given value.  If an
220  * attribute with the given name does not exist, it will be created.  If
221  * an attribute with the given name already exists, the previous value
222  * will be overwritten.  The integer_size may be different from the
223  * existing attribute's integer size, in which case the attribute's
224  * integer size will be updated to the new value.
225  */
226 int zap_update(objset_t *ds, uint64_t zapobj, const char *name,
227     int integer_size, uint64_t num_integers, const void *val, dmu_tx_t *tx);
228 int zap_update_uint64(objset_t *os, uint64_t zapobj, const uint64_t *key,
229     int key_numints,
230     int integer_size, uint64_t num_integers, const void *val, dmu_tx_t *tx);
231 
232 /*
233  * Get the length (in integers) and the integer size of the specified
234  * attribute.
235  *
236  * If the requested attribute does not exist, the call will fail and
237  * return ENOENT.
238  */
239 int zap_length(objset_t *ds, uint64_t zapobj, const char *name,
240     uint64_t *integer_size, uint64_t *num_integers);
241 int zap_length_uint64(objset_t *os, uint64_t zapobj, const uint64_t *key,
242     int key_numints, uint64_t *integer_size, uint64_t *num_integers);
243 
244 /*
245  * Remove the specified attribute.
246  *
247  * If the specified attribute does not exist, the call will fail and
248  * return ENOENT.
249  */
250 int zap_remove(objset_t *ds, uint64_t zapobj, const char *name, dmu_tx_t *tx);
251 int zap_remove_norm(objset_t *ds, uint64_t zapobj, const char *name,
252     matchtype_t mt, dmu_tx_t *tx);
253 int zap_remove_uint64(objset_t *os, uint64_t zapobj, const uint64_t *key,
254     int key_numints, dmu_tx_t *tx);
255 
256 /*
257  * Returns (in *count) the number of attributes in the specified zap
258  * object.
259  */
260 int zap_count(objset_t *ds, uint64_t zapobj, uint64_t *count);
261 
262 
263 /*
264  * Returns (in name) the name of the entry whose (value & mask)
265  * (za_first_integer) is value, or ENOENT if not found.  The string
266  * pointed to by name must be at least 256 bytes long.  If mask==0, the
267  * match must be exact (ie, same as mask=-1ULL).
268  */
269 int zap_value_search(objset_t *os, uint64_t zapobj,
270     uint64_t value, uint64_t mask, char *name);
271 
272 /*
273  * Transfer all the entries from fromobj into intoobj.  Only works on
274  * int_size=8 num_integers=1 values.  Fails if there are any duplicated
275  * entries.
276  */
277 int zap_join(objset_t *os, uint64_t fromobj, uint64_t intoobj, dmu_tx_t *tx);
278 
279 /*
280  * Manipulate entries where the name + value are the "same" (the name is
281  * a stringified version of the value).
282  */
283 int zap_add_int(objset_t *os, uint64_t obj, uint64_t value, dmu_tx_t *tx);
284 int zap_remove_int(objset_t *os, uint64_t obj, uint64_t value, dmu_tx_t *tx);
285 int zap_lookup_int(objset_t *os, uint64_t obj, uint64_t value);
286 int zap_increment_int(objset_t *os, uint64_t obj, uint64_t key, int64_t delta,
287     dmu_tx_t *tx);
288 
289 struct zap;
290 struct zap_leaf;
291 typedef struct zap_cursor {
292 	/* This structure is opaque! */
293 	objset_t *zc_objset;
294 	struct zap *zc_zap;
295 	struct zap_leaf *zc_leaf;
296 	uint64_t zc_zapobj;
297 	uint64_t zc_serialized;
298 	uint64_t zc_hash;
299 	uint32_t zc_cd;
300 } zap_cursor_t;
301 
302 typedef struct {
303 	int za_integer_length;
304 	/*
305 	 * za_normalization_conflict will be set if there are additional
306 	 * entries with this normalized form (eg, "foo" and "Foo").
307 	 */
308 	boolean_t za_normalization_conflict;
309 	uint64_t za_num_integers;
310 	uint64_t za_first_integer;	/* no sign extension for <8byte ints */
311 	char za_name[MAXNAMELEN];
312 } zap_attribute_t;
313 
314 /*
315  * The interface for listing all the attributes of a zapobj can be
316  * thought of as cursor moving down a list of the attributes one by
317  * one.  The cookie returned by the zap_cursor_serialize routine is
318  * persistent across system calls (and across reboot, even).
319  */
320 
321 /*
322  * Initialize a zap cursor, pointing to the "first" attribute of the
323  * zapobj.  You must _fini the cursor when you are done with it.
324  */
325 void zap_cursor_init(zap_cursor_t *zc, objset_t *ds, uint64_t zapobj);
326 void zap_cursor_fini(zap_cursor_t *zc);
327 
328 /*
329  * Get the attribute currently pointed to by the cursor.  Returns
330  * ENOENT if at the end of the attributes.
331  */
332 int zap_cursor_retrieve(zap_cursor_t *zc, zap_attribute_t *za);
333 
334 /*
335  * Advance the cursor to the next attribute.
336  */
337 void zap_cursor_advance(zap_cursor_t *zc);
338 
339 /*
340  * Get a persistent cookie pointing to the current position of the zap
341  * cursor.  The low 4 bits in the cookie are always zero, and thus can
342  * be used as to differentiate a serialized cookie from a different type
343  * of value.  The cookie will be less than 2^32 as long as there are
344  * fewer than 2^22 (4.2 million) entries in the zap object.
345  */
346 uint64_t zap_cursor_serialize(zap_cursor_t *zc);
347 
348 /*
349  * Advance the cursor to the attribute having the given key.
350  */
351 int zap_cursor_move_to_key(zap_cursor_t *zc, const char *name, matchtype_t mt);
352 
353 /*
354  * Initialize a zap cursor pointing to the position recorded by
355  * zap_cursor_serialize (in the "serialized" argument).  You can also
356  * use a "serialized" argument of 0 to start at the beginning of the
357  * zapobj (ie.  zap_cursor_init_serialized(..., 0) is equivalent to
358  * zap_cursor_init(...).)
359  */
360 void zap_cursor_init_serialized(zap_cursor_t *zc, objset_t *ds,
361     uint64_t zapobj, uint64_t serialized);
362 
363 
364 #define	ZAP_HISTOGRAM_SIZE 10
365 
366 typedef struct zap_stats {
367 	/*
368 	 * Size of the pointer table (in number of entries).
369 	 * This is always a power of 2, or zero if it's a microzap.
370 	 * In general, it should be considerably greater than zs_num_leafs.
371 	 */
372 	uint64_t zs_ptrtbl_len;
373 
374 	uint64_t zs_blocksize;		/* size of zap blocks */
375 
376 	/*
377 	 * The number of blocks used.  Note that some blocks may be
378 	 * wasted because old ptrtbl's and large name/value blocks are
379 	 * not reused.  (Although their space is reclaimed, we don't
380 	 * reuse those offsets in the object.)
381 	 */
382 	uint64_t zs_num_blocks;
383 
384 	/*
385 	 * Pointer table values from zap_ptrtbl in the zap_phys_t
386 	 */
387 	uint64_t zs_ptrtbl_nextblk;	  /* next (larger) copy start block */
388 	uint64_t zs_ptrtbl_blks_copied;   /* number source blocks copied */
389 	uint64_t zs_ptrtbl_zt_blk;	  /* starting block number */
390 	uint64_t zs_ptrtbl_zt_numblks;    /* number of blocks */
391 	uint64_t zs_ptrtbl_zt_shift;	  /* bits to index it */
392 
393 	/*
394 	 * Values of the other members of the zap_phys_t
395 	 */
396 	uint64_t zs_block_type;		/* ZBT_HEADER */
397 	uint64_t zs_magic;		/* ZAP_MAGIC */
398 	uint64_t zs_num_leafs;		/* The number of leaf blocks */
399 	uint64_t zs_num_entries;	/* The number of zap entries */
400 	uint64_t zs_salt;		/* salt to stir into hash function */
401 
402 	/*
403 	 * Histograms.  For all histograms, the last index
404 	 * (ZAP_HISTOGRAM_SIZE-1) includes any values which are greater
405 	 * than what can be represented.  For example
406 	 * zs_leafs_with_n5_entries[ZAP_HISTOGRAM_SIZE-1] is the number
407 	 * of leafs with more than 45 entries.
408 	 */
409 
410 	/*
411 	 * zs_leafs_with_n_pointers[n] is the number of leafs with
412 	 * 2^n pointers to it.
413 	 */
414 	uint64_t zs_leafs_with_2n_pointers[ZAP_HISTOGRAM_SIZE];
415 
416 	/*
417 	 * zs_leafs_with_n_entries[n] is the number of leafs with
418 	 * [n*5, (n+1)*5) entries.  In the current implementation, there
419 	 * can be at most 55 entries in any block, but there may be
420 	 * fewer if the name or value is large, or the block is not
421 	 * completely full.
422 	 */
423 	uint64_t zs_blocks_with_n5_entries[ZAP_HISTOGRAM_SIZE];
424 
425 	/*
426 	 * zs_leafs_n_tenths_full[n] is the number of leafs whose
427 	 * fullness is in the range [n/10, (n+1)/10).
428 	 */
429 	uint64_t zs_blocks_n_tenths_full[ZAP_HISTOGRAM_SIZE];
430 
431 	/*
432 	 * zs_entries_using_n_chunks[n] is the number of entries which
433 	 * consume n 24-byte chunks.  (Note, large names/values only use
434 	 * one chunk, but contribute to zs_num_blocks_large.)
435 	 */
436 	uint64_t zs_entries_using_n_chunks[ZAP_HISTOGRAM_SIZE];
437 
438 	/*
439 	 * zs_buckets_with_n_entries[n] is the number of buckets (each
440 	 * leaf has 64 buckets) with n entries.
441 	 * zs_buckets_with_n_entries[1] should be very close to
442 	 * zs_num_entries.
443 	 */
444 	uint64_t zs_buckets_with_n_entries[ZAP_HISTOGRAM_SIZE];
445 } zap_stats_t;
446 
447 /*
448  * Get statistics about a ZAP object.  Note: you need to be aware of the
449  * internal implementation of the ZAP to correctly interpret some of the
450  * statistics.  This interface shouldn't be relied on unless you really
451  * know what you're doing.
452  */
453 int zap_get_stats(objset_t *ds, uint64_t zapobj, zap_stats_t *zs);
454 
455 #ifdef	__cplusplus
456 }
457 #endif
458 
459 #endif	/* _SYS_ZAP_H */
460