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) 2016 Gvozden Nešković. All rights reserved.
23  */
24 
25 #ifndef _VDEV_RAIDZ_H
26 #define	_VDEV_RAIDZ_H
27 
28 #include <sys/types.h>
29 #include <sys/debug.h>
30 #include <sys/kstat.h>
31 #include <sys/abd.h>
32 
33 #ifdef  __cplusplus
34 extern "C" {
35 #endif
36 
37 #define	CODE_P		(0U)
38 #define	CODE_Q		(1U)
39 #define	CODE_R		(2U)
40 
41 #define	PARITY_P	(1U)
42 #define	PARITY_PQ	(2U)
43 #define	PARITY_PQR	(3U)
44 
45 #define	TARGET_X	(0U)
46 #define	TARGET_Y	(1U)
47 #define	TARGET_Z	(2U)
48 
49 /*
50  * Parity generation methods indexes
51  */
52 enum raidz_math_gen_op {
53 	RAIDZ_GEN_P = 0,
54 	RAIDZ_GEN_PQ,
55 	RAIDZ_GEN_PQR,
56 	RAIDZ_GEN_NUM = 3
57 };
58 /*
59  * Data reconstruction methods indexes
60  */
61 enum raidz_rec_op {
62 	RAIDZ_REC_P = 0,
63 	RAIDZ_REC_Q,
64 	RAIDZ_REC_R,
65 	RAIDZ_REC_PQ,
66 	RAIDZ_REC_PR,
67 	RAIDZ_REC_QR,
68 	RAIDZ_REC_PQR,
69 	RAIDZ_REC_NUM = 7
70 };
71 
72 extern const char *raidz_gen_name[RAIDZ_GEN_NUM];
73 extern const char *raidz_rec_name[RAIDZ_REC_NUM];
74 
75 /*
76  * Methods used to define raidz implementation
77  *
78  * @raidz_gen_f	Parity generation function
79  *     @par1	pointer to raidz_map
80  * @raidz_rec_f	Data reconstruction function
81  *     @par1	pointer to raidz_map
82  *     @par2	array of reconstruction targets
83  * @will_work_f Function returns TRUE if impl. is supported on the system
84  * @init_impl_f Function is called once on init
85  * @fini_impl_f Function is called once on fini
86  */
87 typedef void		(*raidz_gen_f)(void *);
88 typedef int		(*raidz_rec_f)(void *, const int *);
89 typedef boolean_t	(*will_work_f)(void);
90 typedef void		(*init_impl_f)(void);
91 typedef void		(*fini_impl_f)(void);
92 
93 #define	RAIDZ_IMPL_NAME_MAX	(20)
94 
95 typedef struct raidz_impl_ops {
96 	init_impl_f init;
97 	fini_impl_f fini;
98 	raidz_gen_f gen[RAIDZ_GEN_NUM];	/* Parity generate functions */
99 	raidz_rec_f rec[RAIDZ_REC_NUM];	/* Data reconstruction functions */
100 	will_work_f is_supported;	/* Support check function */
101 	char name[RAIDZ_IMPL_NAME_MAX];	/* Name of the implementation */
102 } raidz_impl_ops_t;
103 
104 typedef struct raidz_col {
105 	size_t rc_devidx;		/* child device index for I/O */
106 	size_t rc_offset;		/* device offset */
107 	size_t rc_size;			/* I/O size */
108 	abd_t *rc_abd;			/* I/O data */
109 	void *rc_gdata;			/* used to store the "good" version */
110 	int rc_error;			/* I/O error for this device */
111 	unsigned int rc_tried;		/* Did we attempt this I/O column? */
112 	unsigned int rc_skipped;	/* Did we skip this I/O column? */
113 } raidz_col_t;
114 
115 typedef struct raidz_map {
116 	size_t rm_cols;			/* Regular column count */
117 	size_t rm_scols;		/* Count including skipped columns */
118 	size_t rm_bigcols;		/* Number of oversized columns */
119 	size_t rm_asize;		/* Actual total I/O size */
120 	size_t rm_missingdata;		/* Count of missing data devices */
121 	size_t rm_missingparity;	/* Count of missing parity devices */
122 	size_t rm_firstdatacol;		/* First data column/parity count */
123 	size_t rm_nskip;		/* Skipped sectors for padding */
124 	size_t rm_skipstart;		/* Column index of padding start */
125 	void *rm_abd_copy;		/* rm_asize-buffer of copied data */
126 	size_t rm_reports;		/* # of referencing checksum reports */
127 	unsigned int rm_freed;		/* map no longer has referencing ZIO */
128 	unsigned int rm_ecksuminjected;	/* checksum error was injected */
129 	const raidz_impl_ops_t *rm_ops;	/* RAIDZ math operations */
130 	raidz_col_t rm_col[1];		/* Flexible array of I/O columns */
131 } raidz_map_t;
132 
133 #define	RAIDZ_ORIGINAL_IMPL	(INT_MAX)
134 
135 extern const raidz_impl_ops_t vdev_raidz_scalar_impl;
136 
137 /*
138  * Commonly used raidz_map helpers
139  *
140  * raidz_parity		Returns parity of the RAIDZ block
141  * raidz_ncols		Returns number of columns the block spans
142  * raidz_nbigcols	Returns number of big columns columns
143  * raidz_col_p		Returns pointer to a column
144  * raidz_col_size	Returns size of a column
145  * raidz_big_size	Returns size of big columns
146  * raidz_short_size	Returns size of short columns
147  */
148 #define	raidz_parity(rm)	((rm)->rm_firstdatacol)
149 #define	raidz_ncols(rm)		((rm)->rm_cols)
150 #define	raidz_nbigcols(rm)	((rm)->rm_bigcols)
151 #define	raidz_col_p(rm, c)	((rm)->rm_col + (c))
152 #define	raidz_col_size(rm, c)	((rm)->rm_col[c].rc_size)
153 #define	raidz_big_size(rm)	(raidz_col_size(rm, CODE_P))
154 #define	raidz_short_size(rm)	(raidz_col_size(rm, raidz_ncols(rm)-1))
155 
156 /*
157  * Macro defines an RAIDZ parity generation method
158  *
159  * @code	parity the function produce
160  * @impl	name of the implementation
161  */
162 #define	_RAIDZ_GEN_WRAP(code, impl) 					\
163 static void								\
164 impl ## _gen_ ## code(void *rmp)					\
165 {									\
166 	raidz_map_t *rm = (raidz_map_t *) rmp;				\
167 	raidz_generate_## code ## _impl(rm); 				\
168 }
169 
170 /*
171  * Macro defines an RAIDZ data reconstruction method
172  *
173  * @code	parity the function produce
174  * @impl	name of the implementation
175  */
176 #define	_RAIDZ_REC_WRAP(code, impl) 					\
177 static int 								\
178 impl ## _rec_ ## code(void *rmp, const int *tgtidx)			\
179 {									\
180 	raidz_map_t *rm = (raidz_map_t *) rmp;				\
181 	return (raidz_reconstruct_## code ## _impl(rm, tgtidx));	\
182 }
183 
184 /*
185  * Define all gen methods for an implementation
186  *
187  * @impl	name of the implementation
188  */
189 #define	DEFINE_GEN_METHODS(impl)					\
190 	_RAIDZ_GEN_WRAP(p, impl);					\
191 	_RAIDZ_GEN_WRAP(pq, impl);					\
192 	_RAIDZ_GEN_WRAP(pqr, impl)
193 
194 /*
195  * Define all rec functions for an implementation
196  *
197  * @impl	name of the implementation
198  */
199 #define	DEFINE_REC_METHODS(impl)					\
200 	_RAIDZ_REC_WRAP(p, impl);					\
201 	_RAIDZ_REC_WRAP(q, impl);					\
202 	_RAIDZ_REC_WRAP(r, impl);					\
203 	_RAIDZ_REC_WRAP(pq, impl);					\
204 	_RAIDZ_REC_WRAP(pr, impl);					\
205 	_RAIDZ_REC_WRAP(qr, impl);					\
206 	_RAIDZ_REC_WRAP(pqr, impl)
207 
208 #define	RAIDZ_GEN_METHODS(impl)						\
209 {									\
210 	[RAIDZ_GEN_P] = & impl ## _gen_p,				\
211 	[RAIDZ_GEN_PQ] = & impl ## _gen_pq,				\
212 	[RAIDZ_GEN_PQR] = & impl ## _gen_pqr				\
213 }
214 
215 #define	RAIDZ_REC_METHODS(impl)						\
216 {									\
217 	[RAIDZ_REC_P] = & impl ## _rec_p,				\
218 	[RAIDZ_REC_Q] = & impl ## _rec_q,				\
219 	[RAIDZ_REC_R] = & impl ## _rec_r,				\
220 	[RAIDZ_REC_PQ] = & impl ## _rec_pq,				\
221 	[RAIDZ_REC_PR] = & impl ## _rec_pr,				\
222 	[RAIDZ_REC_QR] = & impl ## _rec_qr,				\
223 	[RAIDZ_REC_PQR] = & impl ## _rec_pqr				\
224 }
225 
226 
227 typedef struct raidz_impl_kstat {
228 	uint64_t gen[RAIDZ_GEN_NUM];	/* gen method speed kiB/s */
229 	uint64_t rec[RAIDZ_REC_NUM];	/* rec method speed kiB/s */
230 } raidz_impl_kstat_t;
231 
232 /*
233  * Enumerate various multiplication constants
234  * used in reconstruction methods
235  */
236 typedef enum raidz_mul_info {
237 	/* Reconstruct Q */
238 	MUL_Q_X		= 0,
239 	/* Reconstruct R */
240 	MUL_R_X		= 0,
241 	/* Reconstruct PQ */
242 	MUL_PQ_X	= 0,
243 	MUL_PQ_Y	= 1,
244 	/* Reconstruct PR */
245 	MUL_PR_X	= 0,
246 	MUL_PR_Y	= 1,
247 	/* Reconstruct QR */
248 	MUL_QR_XQ	= 0,
249 	MUL_QR_X	= 1,
250 	MUL_QR_YQ	= 2,
251 	MUL_QR_Y	= 3,
252 	/* Reconstruct PQR */
253 	MUL_PQR_XP	= 0,
254 	MUL_PQR_XQ	= 1,
255 	MUL_PQR_XR	= 2,
256 	MUL_PQR_YU	= 3,
257 	MUL_PQR_YP	= 4,
258 	MUL_PQR_YQ	= 5,
259 
260 	MUL_CNT		= 6
261 } raidz_mul_info_t;
262 
263 /*
264  * Powers of 2 in the Galois field.
265  */
266 extern const uint8_t vdev_raidz_pow2[256] __attribute__((aligned(256)));
267 /* Logs of 2 in the Galois field defined above. */
268 extern const uint8_t vdev_raidz_log2[256] __attribute__((aligned(256)));
269 
270 /*
271  * Multiply a given number by 2 raised to the given power.
272  */
273 static inline uint8_t
274 vdev_raidz_exp2(const uint8_t a, const unsigned exp)
275 {
276 	if (a == 0)
277 		return (0);
278 
279 	return (vdev_raidz_pow2[(exp + (unsigned) vdev_raidz_log2[a]) % 255]);
280 }
281 
282 /*
283  * Galois Field operations.
284  *
285  * gf_exp2	- computes 2 raised to the given power
286  * gf_exp2	- computes 4 raised to the given power
287  * gf_mul	- multiplication
288  * gf_div	- division
289  * gf_inv	- multiplicative inverse
290  */
291 typedef unsigned gf_t;
292 typedef unsigned gf_log_t;
293 
294 static inline gf_t
295 gf_mul(const gf_t a, const gf_t b)
296 {
297 	gf_log_t logsum;
298 
299 	if (a == 0 || b == 0)
300 		return (0);
301 
302 	logsum = (gf_log_t) vdev_raidz_log2[a] + (gf_log_t) vdev_raidz_log2[b];
303 
304 	return ((gf_t) vdev_raidz_pow2[logsum % 255]);
305 }
306 
307 static inline gf_t
308 gf_div(const gf_t  a, const gf_t b)
309 {
310 	gf_log_t logsum;
311 
312 	ASSERT3U(b, >, 0);
313 	if (a == 0)
314 		return (0);
315 
316 	logsum = (gf_log_t) 255 + (gf_log_t) vdev_raidz_log2[a] -
317 	    (gf_log_t) vdev_raidz_log2[b];
318 
319 	return ((gf_t) vdev_raidz_pow2[logsum % 255]);
320 }
321 
322 static inline gf_t
323 gf_inv(const gf_t a)
324 {
325 	gf_log_t logsum;
326 
327 	ASSERT3U(a, >, 0);
328 
329 	logsum = (gf_log_t) 255 - (gf_log_t) vdev_raidz_log2[a];
330 
331 	return ((gf_t) vdev_raidz_pow2[logsum]);
332 }
333 
334 static inline gf_t
335 gf_exp2(gf_log_t exp)
336 {
337 	return (vdev_raidz_pow2[exp % 255]);
338 }
339 
340 static inline gf_t
341 gf_exp4(gf_log_t exp)
342 {
343 	ASSERT3U(exp, <=, 255);
344 	return ((gf_t) vdev_raidz_pow2[(2 * exp) % 255]);
345 }
346 
347 #ifdef  __cplusplus
348 }
349 #endif
350 
351 #endif /* _VDEV_RAIDZ_H */
352