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25 * Copyright 2017 Nexenta Systems, Inc.
32 * ZAP - ZFS Attribute Processor
34 * The ZAP is a module which sits on top of the DMU (Data Management
35 * Unit) and implements a higher-level storage primitive using DMU
36 * objects. Its primary consumer is the ZPL (ZFS Posix Layer).
38 * A "zapobj" is a DMU object which the ZAP uses to stores attributes.
39 * Users should use only zap routines to access a zapobj - they should
40 * not access the DMU object directly using DMU routines.
42 * The attributes stored in a zapobj are name-value pairs. The name is
43 * a zero-terminated string of up to ZAP_MAXNAMELEN bytes (including
44 * terminating NULL). The value is an array of integers, which may be
45 * 1, 2, 4, or 8 bytes long. The total space used by the array (number
46 * of integers * integer length) can be up to ZAP_MAXVALUELEN bytes.
47 * Note that an 8-byte integer value can be used to store the location
48 * (object number) of another dmu object (which may be itself a zapobj).
49 * Note that you can use a zero-length attribute to store a single bit
50 * of information - the attribute is present or not.
52 * The ZAP routines are thread-safe. However, you must observe the
53 * DMU's restriction that a transaction may not be operated on
56 * Any of the routines that return an int may return an I/O error (EIO
60 * Implementation / Performance Notes:
62 * The ZAP is intended to operate most efficiently on attributes with
63 * short (49 bytes or less) names and single 8-byte values, for which
64 * the microzap will be used. The ZAP should be efficient enough so
65 * that the user does not need to cache these attributes.
67 * The ZAP's locking scheme makes its routines thread-safe. Operations
68 * on different zapobjs will be processed concurrently. Operations on
69 * the same zapobj which only read data will be processed concurrently.
70 * Operations on the same zapobj which modify data will be processed
71 * concurrently when there are many attributes in the zapobj (because
72 * the ZAP uses per-block locking - more than 128 * (number of cpus)
73 * small attributes will suffice).
77 * We're using zero-terminated byte strings (ie. ASCII or UTF-8 C
78 * strings) for the names of attributes, rather than a byte string
79 * bounded by an explicit length. If some day we want to support names
80 * in character sets which have embedded zeros (eg. UTF-16, UTF-32),
81 * we'll have to add routines for using length-bounded strings.
85 #include <sys/refcount.h>
92 * Specifies matching criteria for ZAP lookups.
93 * MT_NORMALIZE Use ZAP normalization flags, which can include both
94 * unicode normalization and case-insensitivity.
95 * MT_MATCH_CASE Do case-sensitive lookups even if MT_NORMALIZE is
96 * specified and ZAP normalization flags include
97 * U8_TEXTPREP_TOUPPER.
99 typedef enum matchtype {
100 MT_NORMALIZE = 1 << 0,
101 MT_MATCH_CASE = 1 << 1,
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,
110 * First word of key (which must be an array of uint64) is
111 * already randomly distributed.
113 ZAP_FLAG_PRE_HASHED_KEY = 1 << 2,
117 * Create a new zapobj with no attributes and return its object number.
119 * dnodesize specifies the on-disk size of the dnode for the new zapobj.
120 * Valid values are multiples of 512 up to DNODE_MAX_SIZE.
122 uint64_t zap_create(objset_t *ds, dmu_object_type_t ot,
123 dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *tx);
124 uint64_t zap_create_dnsize(objset_t *ds, dmu_object_type_t ot,
125 dmu_object_type_t bonustype, int bonuslen, int dnodesize, dmu_tx_t *tx);
126 uint64_t zap_create_norm(objset_t *ds, int normflags, dmu_object_type_t ot,
127 dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *tx);
128 uint64_t zap_create_norm_dnsize(objset_t *ds, int normflags,
129 dmu_object_type_t ot, dmu_object_type_t bonustype, int bonuslen,
130 int dnodesize, dmu_tx_t *tx);
131 uint64_t zap_create_flags(objset_t *os, int normflags, zap_flags_t flags,
132 dmu_object_type_t ot, int leaf_blockshift, int indirect_blockshift,
133 dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *tx);
134 uint64_t zap_create_flags_dnsize(objset_t *os, int normflags,
135 zap_flags_t flags, dmu_object_type_t ot, int leaf_blockshift,
136 int indirect_blockshift, dmu_object_type_t bonustype, int bonuslen,
137 int dnodesize, dmu_tx_t *tx);
138 uint64_t zap_create_link(objset_t *os, dmu_object_type_t ot,
139 uint64_t parent_obj, const char *name, dmu_tx_t *tx);
140 uint64_t zap_create_link_dnsize(objset_t *os, dmu_object_type_t ot,
141 uint64_t parent_obj, const char *name, int dnodesize, dmu_tx_t *tx);
142 uint64_t zap_create_link_dnsize(objset_t *os, dmu_object_type_t ot,
143 uint64_t parent_obj, const char *name, int dnodesize, dmu_tx_t *tx);
146 * Initialize an already-allocated object.
148 void mzap_create_impl(objset_t *os, uint64_t obj, int normflags,
149 zap_flags_t flags, dmu_tx_t *tx);
152 * Create a new zapobj with no attributes from the given (unallocated)
155 int zap_create_claim(objset_t *ds, uint64_t obj, dmu_object_type_t ot,
156 dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *tx);
157 int zap_create_claim_dnsize(objset_t *ds, uint64_t obj, dmu_object_type_t ot,
158 dmu_object_type_t bonustype, int bonuslen, int dnodesize, dmu_tx_t *tx);
159 int zap_create_claim_norm(objset_t *ds, uint64_t obj,
160 int normflags, dmu_object_type_t ot,
161 dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *tx);
162 int zap_create_claim_norm_dnsize(objset_t *ds, uint64_t obj,
163 int normflags, dmu_object_type_t ot,
164 dmu_object_type_t bonustype, int bonuslen, int dnodesize, dmu_tx_t *tx);
167 * The zapobj passed in must be a valid ZAP object for all of the
168 * following routines.
172 * Destroy this zapobj and all its attributes.
174 * Frees the object number using dmu_object_free.
176 int zap_destroy(objset_t *ds, uint64_t zapobj, dmu_tx_t *tx);
179 * Manipulate attributes.
181 * 'integer_size' is in bytes, and must be 1, 2, 4, or 8.
185 * Retrieve the contents of the attribute with the given name.
187 * If the requested attribute does not exist, the call will fail and
190 * If 'integer_size' is smaller than the attribute's integer size, the
191 * call will fail and return EINVAL.
193 * If 'integer_size' is equal to or larger than the attribute's integer
194 * size, the call will succeed and return 0.
196 * When converting to a larger integer size, the integers will be treated as
197 * unsigned (ie. no sign-extension will be performed).
199 * 'num_integers' is the length (in integers) of 'buf'.
201 * If the attribute is longer than the buffer, as many integers as will
202 * fit will be transferred to 'buf'. If the entire attribute was not
203 * transferred, the call will return EOVERFLOW.
205 int zap_lookup(objset_t *ds, uint64_t zapobj, const char *name,
206 uint64_t integer_size, uint64_t num_integers, void *buf);
209 * If rn_len is nonzero, realname will be set to the name of the found
210 * entry (which may be different from the requested name if matchtype is
213 * If normalization_conflictp is not NULL, it will be set if there is
214 * another name with the same case/unicode normalized form.
216 int zap_lookup_norm(objset_t *ds, uint64_t zapobj, const char *name,
217 uint64_t integer_size, uint64_t num_integers, void *buf,
218 matchtype_t mt, char *realname, int rn_len,
219 boolean_t *normalization_conflictp);
220 int zap_lookup_uint64(objset_t *os, uint64_t zapobj, const uint64_t *key,
221 int key_numints, uint64_t integer_size, uint64_t num_integers, void *buf);
222 int zap_contains(objset_t *ds, uint64_t zapobj, const char *name);
223 int zap_prefetch_uint64(objset_t *os, uint64_t zapobj, const uint64_t *key,
225 int zap_lookup_by_dnode(dnode_t *dn, const char *name,
226 uint64_t integer_size, uint64_t num_integers, void *buf);
227 int zap_lookup_norm_by_dnode(dnode_t *dn, const char *name,
228 uint64_t integer_size, uint64_t num_integers, void *buf,
229 matchtype_t mt, char *realname, int rn_len,
232 int zap_count_write_by_dnode(dnode_t *dn, const char *name,
233 int add, refcount_t *towrite, refcount_t *tooverwrite);
236 * Create an attribute with the given name and value.
238 * If an attribute with the given name already exists, the call will
239 * fail and return EEXIST.
241 int zap_add(objset_t *ds, uint64_t zapobj, const char *key,
242 int integer_size, uint64_t num_integers,
243 const void *val, dmu_tx_t *tx);
244 int zap_add_by_dnode(dnode_t *dn, const char *key,
245 int integer_size, uint64_t num_integers,
246 const void *val, dmu_tx_t *tx);
247 int zap_add_uint64(objset_t *ds, uint64_t zapobj, const uint64_t *key,
248 int key_numints, int integer_size, uint64_t num_integers,
249 const void *val, dmu_tx_t *tx);
252 * Set the attribute with the given name to the given value. If an
253 * attribute with the given name does not exist, it will be created. If
254 * an attribute with the given name already exists, the previous value
255 * will be overwritten. The integer_size may be different from the
256 * existing attribute's integer size, in which case the attribute's
257 * integer size will be updated to the new value.
259 int zap_update(objset_t *ds, uint64_t zapobj, const char *name,
260 int integer_size, uint64_t num_integers, const void *val, dmu_tx_t *tx);
261 int zap_update_uint64(objset_t *os, uint64_t zapobj, const uint64_t *key,
263 int integer_size, uint64_t num_integers, const void *val, dmu_tx_t *tx);
266 * Get the length (in integers) and the integer size of the specified
269 * If the requested attribute does not exist, the call will fail and
272 int zap_length(objset_t *ds, uint64_t zapobj, const char *name,
273 uint64_t *integer_size, uint64_t *num_integers);
274 int zap_length_uint64(objset_t *os, uint64_t zapobj, const uint64_t *key,
275 int key_numints, uint64_t *integer_size, uint64_t *num_integers);
278 * Remove the specified attribute.
280 * If the specified attribute does not exist, the call will fail and
283 int zap_remove(objset_t *ds, uint64_t zapobj, const char *name, dmu_tx_t *tx);
284 int zap_remove_norm(objset_t *ds, uint64_t zapobj, const char *name,
285 matchtype_t mt, dmu_tx_t *tx);
286 int zap_remove_by_dnode(dnode_t *dn, const char *name, dmu_tx_t *tx);
287 int zap_remove_uint64(objset_t *os, uint64_t zapobj, const uint64_t *key,
288 int key_numints, dmu_tx_t *tx);
291 * Returns (in *count) the number of attributes in the specified zap
294 int zap_count(objset_t *ds, uint64_t zapobj, uint64_t *count);
297 * Returns (in name) the name of the entry whose (value & mask)
298 * (za_first_integer) is value, or ENOENT if not found. The string
299 * pointed to by name must be at least 256 bytes long. If mask==0, the
300 * match must be exact (ie, same as mask=-1ULL).
302 int zap_value_search(objset_t *os, uint64_t zapobj,
303 uint64_t value, uint64_t mask, char *name);
306 * Transfer all the entries from fromobj into intoobj. Only works on
307 * int_size=8 num_integers=1 values. Fails if there are any duplicated
310 int zap_join(objset_t *os, uint64_t fromobj, uint64_t intoobj, dmu_tx_t *tx);
312 /* Same as zap_join, but set the values to 'value'. */
313 int zap_join_key(objset_t *os, uint64_t fromobj, uint64_t intoobj,
314 uint64_t value, dmu_tx_t *tx);
316 /* Same as zap_join, but add together any duplicated entries. */
317 int zap_join_increment(objset_t *os, uint64_t fromobj, uint64_t intoobj,
321 * Manipulate entries where the name + value are the "same" (the name is
322 * a stringified version of the value).
324 int zap_add_int(objset_t *os, uint64_t obj, uint64_t value, dmu_tx_t *tx);
325 int zap_remove_int(objset_t *os, uint64_t obj, uint64_t value, dmu_tx_t *tx);
326 int zap_lookup_int(objset_t *os, uint64_t obj, uint64_t value);
327 int zap_increment_int(objset_t *os, uint64_t obj, uint64_t key, int64_t delta,
330 /* Here the key is an int and the value is a different int. */
331 int zap_add_int_key(objset_t *os, uint64_t obj,
332 uint64_t key, uint64_t value, dmu_tx_t *tx);
333 int zap_update_int_key(objset_t *os, uint64_t obj,
334 uint64_t key, uint64_t value, dmu_tx_t *tx);
335 int zap_lookup_int_key(objset_t *os, uint64_t obj,
336 uint64_t key, uint64_t *valuep);
338 int zap_increment(objset_t *os, uint64_t obj, const char *name, int64_t delta,
343 typedef struct zap_cursor {
344 /* This structure is opaque! */
347 struct zap_leaf *zc_leaf;
349 uint64_t zc_serialized;
352 boolean_t zc_prefetch;
356 int za_integer_length;
358 * za_normalization_conflict will be set if there are additional
359 * entries with this normalized form (eg, "foo" and "Foo").
361 boolean_t za_normalization_conflict;
362 uint64_t za_num_integers;
363 uint64_t za_first_integer; /* no sign extension for <8byte ints */
364 char za_name[ZAP_MAXNAMELEN];
368 * The interface for listing all the attributes of a zapobj can be
369 * thought of as cursor moving down a list of the attributes one by
370 * one. The cookie returned by the zap_cursor_serialize routine is
371 * persistent across system calls (and across reboot, even).
375 * Initialize a zap cursor, pointing to the "first" attribute of the
376 * zapobj. You must _fini the cursor when you are done with it.
378 void zap_cursor_init(zap_cursor_t *zc, objset_t *ds, uint64_t zapobj);
379 void zap_cursor_init_noprefetch(zap_cursor_t *zc, objset_t *os,
381 void zap_cursor_fini(zap_cursor_t *zc);
384 * Get the attribute currently pointed to by the cursor. Returns
385 * ENOENT if at the end of the attributes.
387 int zap_cursor_retrieve(zap_cursor_t *zc, zap_attribute_t *za);
390 * Advance the cursor to the next attribute.
392 void zap_cursor_advance(zap_cursor_t *zc);
395 * Get a persistent cookie pointing to the current position of the zap
396 * cursor. The low 4 bits in the cookie are always zero, and thus can
397 * be used as to differentiate a serialized cookie from a different type
398 * of value. The cookie will be less than 2^32 as long as there are
399 * fewer than 2^22 (4.2 million) entries in the zap object.
401 uint64_t zap_cursor_serialize(zap_cursor_t *zc);
404 * Advance the cursor to the attribute having the given key.
406 int zap_cursor_move_to_key(zap_cursor_t *zc, const char *name, matchtype_t mt);
409 * Initialize a zap cursor pointing to the position recorded by
410 * zap_cursor_serialize (in the "serialized" argument). You can also
411 * use a "serialized" argument of 0 to start at the beginning of the
412 * zapobj (ie. zap_cursor_init_serialized(..., 0) is equivalent to
413 * zap_cursor_init(...).)
415 void zap_cursor_init_serialized(zap_cursor_t *zc, objset_t *ds,
416 uint64_t zapobj, uint64_t serialized);
419 #define ZAP_HISTOGRAM_SIZE 10
421 typedef struct zap_stats {
423 * Size of the pointer table (in number of entries).
424 * This is always a power of 2, or zero if it's a microzap.
425 * In general, it should be considerably greater than zs_num_leafs.
427 uint64_t zs_ptrtbl_len;
429 uint64_t zs_blocksize; /* size of zap blocks */
432 * The number of blocks used. Note that some blocks may be
433 * wasted because old ptrtbl's and large name/value blocks are
434 * not reused. (Although their space is reclaimed, we don't
435 * reuse those offsets in the object.)
437 uint64_t zs_num_blocks;
440 * Pointer table values from zap_ptrtbl in the zap_phys_t
442 uint64_t zs_ptrtbl_nextblk; /* next (larger) copy start block */
443 uint64_t zs_ptrtbl_blks_copied; /* number source blocks copied */
444 uint64_t zs_ptrtbl_zt_blk; /* starting block number */
445 uint64_t zs_ptrtbl_zt_numblks; /* number of blocks */
446 uint64_t zs_ptrtbl_zt_shift; /* bits to index it */
449 * Values of the other members of the zap_phys_t
451 uint64_t zs_block_type; /* ZBT_HEADER */
452 uint64_t zs_magic; /* ZAP_MAGIC */
453 uint64_t zs_num_leafs; /* The number of leaf blocks */
454 uint64_t zs_num_entries; /* The number of zap entries */
455 uint64_t zs_salt; /* salt to stir into hash function */
458 * Histograms. For all histograms, the last index
459 * (ZAP_HISTOGRAM_SIZE-1) includes any values which are greater
460 * than what can be represented. For example
461 * zs_leafs_with_n5_entries[ZAP_HISTOGRAM_SIZE-1] is the number
462 * of leafs with more than 45 entries.
466 * zs_leafs_with_n_pointers[n] is the number of leafs with
467 * 2^n pointers to it.
469 uint64_t zs_leafs_with_2n_pointers[ZAP_HISTOGRAM_SIZE];
472 * zs_leafs_with_n_entries[n] is the number of leafs with
473 * [n*5, (n+1)*5) entries. In the current implementation, there
474 * can be at most 55 entries in any block, but there may be
475 * fewer if the name or value is large, or the block is not
478 uint64_t zs_blocks_with_n5_entries[ZAP_HISTOGRAM_SIZE];
481 * zs_leafs_n_tenths_full[n] is the number of leafs whose
482 * fullness is in the range [n/10, (n+1)/10).
484 uint64_t zs_blocks_n_tenths_full[ZAP_HISTOGRAM_SIZE];
487 * zs_entries_using_n_chunks[n] is the number of entries which
488 * consume n 24-byte chunks. (Note, large names/values only use
489 * one chunk, but contribute to zs_num_blocks_large.)
491 uint64_t zs_entries_using_n_chunks[ZAP_HISTOGRAM_SIZE];
494 * zs_buckets_with_n_entries[n] is the number of buckets (each
495 * leaf has 64 buckets) with n entries.
496 * zs_buckets_with_n_entries[1] should be very close to
499 uint64_t zs_buckets_with_n_entries[ZAP_HISTOGRAM_SIZE];
503 * Get statistics about a ZAP object. Note: you need to be aware of the
504 * internal implementation of the ZAP to correctly interpret some of the
505 * statistics. This interface shouldn't be relied on unless you really
506 * know what you're doing.
508 int zap_get_stats(objset_t *ds, uint64_t zapobj, zap_stats_t *zs);
514 #endif /* _SYS_ZAP_H */