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 2010 Sun Microsystems, Inc. All rights reserved.
23 * Use is subject to license terms.
24 */
25
26 /*
27 * Copyright (c) 2013 by Delphix. All rights reserved.
28 */
29
30 #include <sys/zfs_context.h>
31 #include <sys/spa.h>
32 #include <sys/vdev_impl.h>
33 #include <sys/zio.h>
34 #include <sys/fs/zfs.h>
35
36 /*
37 * Virtual device vector for mirroring.
38 */
39
40 typedef struct mirror_child {
41 vdev_t *mc_vd;
42 uint64_t mc_offset;
43 int mc_error;
44 uint8_t mc_tried;
45 uint8_t mc_skipped;
46 uint8_t mc_speculative;
47 } mirror_child_t;
48
49 typedef struct mirror_map {
50 int mm_children;
51 int mm_replacing;
52 int mm_preferred;
53 int mm_root;
54 mirror_child_t mm_child[1];
55 } mirror_map_t;
56
57 int vdev_mirror_shift = 21;
58
59 static void
60 vdev_mirror_map_free(zio_t *zio)
61 {
62 mirror_map_t *mm = zio->io_vsd;
63
64 kmem_free(mm, offsetof(mirror_map_t, mm_child[mm->mm_children]));
65 }
66
67 static const zio_vsd_ops_t vdev_mirror_vsd_ops = {
68 vdev_mirror_map_free,
69 zio_vsd_default_cksum_report
70 };
71
72 static mirror_map_t *
73 vdev_mirror_map_alloc(zio_t *zio)
74 {
75 mirror_map_t *mm = NULL;
76 mirror_child_t *mc;
77 vdev_t *vd = zio->io_vd;
78 int c, d;
79
80 if (vd == NULL) {
81 dva_t *dva = zio->io_bp->blk_dva;
82 spa_t *spa = zio->io_spa;
83
84 c = BP_GET_NDVAS(zio->io_bp);
85
86 mm = kmem_zalloc(offsetof(mirror_map_t, mm_child[c]), KM_SLEEP);
87 mm->mm_children = c;
88 mm->mm_replacing = B_FALSE;
89 mm->mm_preferred = spa_get_random(c);
90 mm->mm_root = B_TRUE;
91
92 /*
93 * Check the other, lower-index DVAs to see if they're on
94 * the same vdev as the child we picked. If they are, use
95 * them since they are likely to have been allocated from
96 * the primary metaslab in use at the time, and hence are
97 * more likely to have locality with single-copy data.
98 */
99 for (c = mm->mm_preferred, d = c - 1; d >= 0; d--) {
100 if (DVA_GET_VDEV(&dva[d]) == DVA_GET_VDEV(&dva[c]))
101 mm->mm_preferred = d;
102 }
103
104 for (c = 0; c < mm->mm_children; c++) {
105 mc = &mm->mm_child[c];
106
107 mc->mc_vd = vdev_lookup_top(spa, DVA_GET_VDEV(&dva[c]));
108 mc->mc_offset = DVA_GET_OFFSET(&dva[c]);
109 }
110 } else {
111 c = vd->vdev_children;
112
113 mm = kmem_zalloc(offsetof(mirror_map_t, mm_child[c]), KM_SLEEP);
114 mm->mm_children = c;
115 mm->mm_replacing = (vd->vdev_ops == &vdev_replacing_ops ||
116 vd->vdev_ops == &vdev_spare_ops);
117 mm->mm_preferred = mm->mm_replacing ? 0 :
118 (zio->io_offset >> vdev_mirror_shift) % c;
119 mm->mm_root = B_FALSE;
120
121 for (c = 0; c < mm->mm_children; c++) {
122 mc = &mm->mm_child[c];
123 mc->mc_vd = vd->vdev_child[c];
124 mc->mc_offset = zio->io_offset;
125 }
126 }
127
128 zio->io_vsd = mm;
129 zio->io_vsd_ops = &vdev_mirror_vsd_ops;
130 return (mm);
131 }
132
133 static int
134 vdev_mirror_open(vdev_t *vd, uint64_t *asize, uint64_t *max_asize,
135 uint64_t *ashift)
136 {
137 int numerrors = 0;
138 int lasterror = 0;
139
140 if (vd->vdev_children == 0) {
192 zio_t *pio;
193
194 mutex_enter(&zio->io_lock);
195 while ((pio = zio_walk_parents(zio)) != NULL) {
196 mutex_enter(&pio->io_lock);
197 ASSERT3U(zio->io_size, >=, pio->io_size);
198 bcopy(zio->io_data, pio->io_data, pio->io_size);
199 mutex_exit(&pio->io_lock);
200 }
201 mutex_exit(&zio->io_lock);
202 }
203
204 zio_buf_free(zio->io_data, zio->io_size);
205
206 mc->mc_error = zio->io_error;
207 mc->mc_tried = 1;
208 mc->mc_skipped = 0;
209 }
210
211 /*
212 * Try to find a child whose DTL doesn't contain the block we want to read.
213 * If we can't, try the read on any vdev we haven't already tried.
214 */
215 static int
216 vdev_mirror_child_select(zio_t *zio)
217 {
218 mirror_map_t *mm = zio->io_vsd;
219 mirror_child_t *mc;
220 uint64_t txg = zio->io_txg;
221 int i, c;
222
223 ASSERT(zio->io_bp == NULL || BP_PHYSICAL_BIRTH(zio->io_bp) == txg);
224
225 /*
226 * Try to find a child whose DTL doesn't contain the block to read.
227 * If a child is known to be completely inaccessible (indicated by
228 * vdev_readable() returning B_FALSE), don't even try.
229 */
230 for (i = 0, c = mm->mm_preferred; i < mm->mm_children; i++, c++) {
231 if (c >= mm->mm_children)
232 c = 0;
233 mc = &mm->mm_child[c];
234 if (mc->mc_tried || mc->mc_skipped)
235 continue;
236 if (!vdev_readable(mc->mc_vd)) {
237 mc->mc_error = SET_ERROR(ENXIO);
238 mc->mc_tried = 1; /* don't even try */
239 mc->mc_skipped = 1;
240 continue;
241 }
242 if (!vdev_dtl_contains(mc->mc_vd, DTL_MISSING, txg, 1))
243 return (c);
244 mc->mc_error = SET_ERROR(ESTALE);
245 mc->mc_skipped = 1;
246 mc->mc_speculative = 1;
247 }
248
249 /*
250 * Every device is either missing or has this txg in its DTL.
251 * Look for any child we haven't already tried before giving up.
252 */
253 for (c = 0; c < mm->mm_children; c++)
254 if (!mm->mm_child[c].mc_tried)
255 return (c);
256
257 /*
258 * Every child failed. There's no place left to look.
259 */
260 return (-1);
261 }
262
263 static int
264 vdev_mirror_io_start(zio_t *zio)
265 {
266 mirror_map_t *mm;
267 mirror_child_t *mc;
268 int c, children;
269
270 mm = vdev_mirror_map_alloc(zio);
271
272 if (zio->io_type == ZIO_TYPE_READ) {
273 if ((zio->io_flags & ZIO_FLAG_SCRUB) && !mm->mm_replacing) {
274 /*
275 * For scrubbing reads we need to allocate a read
276 * buffer for each child and issue reads to all
277 * children. If any child succeeds, it will copy its
278 * data into zio->io_data in vdev_mirror_scrub_done.
279 */
280 for (c = 0; c < mm->mm_children; c++) {
281 mc = &mm->mm_child[c];
282 zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
283 mc->mc_vd, mc->mc_offset,
284 zio_buf_alloc(zio->io_size), zio->io_size,
285 zio->io_type, zio->io_priority, 0,
286 vdev_mirror_scrub_done, mc));
287 }
288 return (ZIO_PIPELINE_CONTINUE);
289 }
290 /*
|
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 2010 Sun Microsystems, Inc. All rights reserved.
23 * Use is subject to license terms.
24 */
25
26 /*
27 * Copyright (c) 2013 by Delphix. All rights reserved.
28 * Copyright (c) 2013 Steven Hartland. All rights reserved.
29 */
30
31 #include <sys/zfs_context.h>
32 #include <sys/spa.h>
33 #include <sys/vdev_impl.h>
34 #include <sys/zio.h>
35 #include <sys/fs/zfs.h>
36
37 /*
38 * Virtual device vector for mirroring.
39 */
40
41 typedef struct mirror_child {
42 vdev_t *mc_vd;
43 uint64_t mc_offset;
44 int mc_error;
45 int mc_load;
46 uint8_t mc_tried;
47 uint8_t mc_skipped;
48 uint8_t mc_speculative;
49 } mirror_child_t;
50
51 typedef struct mirror_map {
52 int *mm_preferred;
53 int mm_preferred_cnt;
54 int mm_children;
55 boolean_t mm_replacing;
56 boolean_t mm_root;
57 mirror_child_t mm_child[];
58 } mirror_map_t;
59
60 int zfs_vdev_mirror_shift = 21;
61
62 /*
63 * The load configuration settings below are tuned by default for
64 * the case where all devices are of the same rotational type.
65 *
66 * If there is a mixture of rotating and non-rotating media, setting
67 * non_rotating_seek_inc to 0 may well provide better results as it
68 * will direct more reads to the non-rotating vdevs which are more
69 * likely to have a higher performance.
70 */
71
72 /* Rotating media load calculation configuration. */
73 /* Rotating media load increment for non-seeking I/O's. */
74 int zfs_vdev_mirror_rotating_inc = 0;
75
76 /* Rotating media load increment for seeking I/O's. */
77 int zfs_vdev_mirror_rotating_seek_inc = 5;
78
79 /*
80 * Offset in bytes from the last I/O which triggers a reduced rotating media
81 * seek increment.
82 */
83 int zfs_vdev_mirror_rotating_seek_offset = 1 * 1024 * 1024;
84
85 /* Non-rotating media load calculation configuration. */
86 /* Non-rotating media load increment for non-seeking I/O's. */
87 int zfs_vdev_mirror_non_rotating_inc = 0;
88
89 /* Non-rotating media load increment for seeking I/O's. */
90 int zfs_vdev_mirror_non_rotating_seek_inc = 1;
91
92 static inline size_t
93 vdev_mirror_map_size(int children)
94 {
95 return (offsetof(mirror_map_t, mm_child[children]) +
96 sizeof (int) * children);
97 }
98
99 static inline mirror_map_t *
100 vdev_mirror_map_alloc(int children, boolean_t replacing, boolean_t root)
101 {
102 mirror_map_t *mm;
103
104 mm = kmem_zalloc(vdev_mirror_map_size(children), KM_SLEEP);
105 mm->mm_children = children;
106 mm->mm_replacing = replacing;
107 mm->mm_root = root;
108 mm->mm_preferred = (int *)((uintptr_t)mm +
109 offsetof(mirror_map_t, mm_child[children]));
110
111 return (mm);
112 }
113
114 static void
115 vdev_mirror_map_free(zio_t *zio)
116 {
117 mirror_map_t *mm = zio->io_vsd;
118
119 kmem_free(mm, vdev_mirror_map_size(mm->mm_children));
120 }
121
122 static const zio_vsd_ops_t vdev_mirror_vsd_ops = {
123 vdev_mirror_map_free,
124 zio_vsd_default_cksum_report
125 };
126
127 /*
128 * Calculate and return the load of the specified vdev adjusted for a zio at
129 * the given offset.
130 *
131 * The calcuation takes into account the vdev's:
132 * 1. Rotation rate
133 * 2. The distance of zio_offset from the last queued request
134 */
135 static int
136 vdev_mirror_load(mirror_map_t *mm, vdev_t *vd, uint64_t zio_offset)
137 {
138 uint64_t lastoffset;
139 int load;
140
141 /* All DVAs have equal weight at the root. */
142 if (mm->mm_root)
143 return (INT_MAX);
144
145 /*
146 * We don't return INT_MAX if the device is resilvering i.e.
147 * vdev_resilver_txg != 0 as when tested performance was slightly
148 * worse overall when resilvering with compared to without.
149 */
150
151 /* Standard load based on pending queue length. */
152 load = vdev_queue_length(vd);
153 lastoffset = vdev_queue_last_queued_offset(vd);
154
155 if (vd->vdev_rotation_rate == VDEV_RATE_NON_ROTATING) {
156 /* Non-rotating media. */
157 if (lastoffset == zio_offset)
158 return (load + zfs_vdev_mirror_non_rotating_inc);
159
160 /*
161 * Apply a seek penalty even for non-rotating devices as
162 * sequential I/O'a can be aggregated into fewer operations
163 * on the device, thus avoiding unnecessary per-command
164 * overhead and boosting performance.
165 */
166 return (load + zfs_vdev_mirror_non_rotating_seek_inc);
167 }
168
169 /* Rotating media I/O's which directly follow the last I/O. */
170 if (lastoffset == zio_offset)
171 return (load + zfs_vdev_mirror_rotating_inc);
172
173 /*
174 * Apply half the seek increment to I/O's within seek offset
175 * of the last I/O queued to this vdev as they should incure less
176 * of a seek increment.
177 */
178 if (ABS(lastoffset - zio_offset) <
179 zfs_vdev_mirror_rotating_seek_offset)
180 return (load + (zfs_vdev_mirror_rotating_seek_inc / 2));
181
182 /* Apply the full seek increment to all other I/O's. */
183 return (load + zfs_vdev_mirror_rotating_seek_inc);
184 }
185
186
187 static mirror_map_t *
188 vdev_mirror_map_init(zio_t *zio)
189 {
190 mirror_map_t *mm = NULL;
191 mirror_child_t *mc;
192 vdev_t *vd = zio->io_vd;
193 int c;
194
195 if (vd == NULL) {
196 dva_t *dva = zio->io_bp->blk_dva;
197 spa_t *spa = zio->io_spa;
198
199 mm = vdev_mirror_map_alloc(BP_GET_NDVAS(zio->io_bp), B_FALSE,
200 B_TRUE);
201 for (c = 0; c < mm->mm_children; c++) {
202 mc = &mm->mm_child[c];
203 mc->mc_vd = vdev_lookup_top(spa, DVA_GET_VDEV(&dva[c]));
204 mc->mc_offset = DVA_GET_OFFSET(&dva[c]);
205 }
206 } else {
207 mm = vdev_mirror_map_alloc(vd->vdev_children,
208 (vd->vdev_ops == &vdev_replacing_ops ||
209 vd->vdev_ops == &vdev_spare_ops), B_FALSE);
210 for (c = 0; c < mm->mm_children; c++) {
211 mc = &mm->mm_child[c];
212 mc->mc_vd = vd->vdev_child[c];
213 mc->mc_offset = zio->io_offset;
214 }
215 }
216
217 zio->io_vsd = mm;
218 zio->io_vsd_ops = &vdev_mirror_vsd_ops;
219 return (mm);
220 }
221
222 static int
223 vdev_mirror_open(vdev_t *vd, uint64_t *asize, uint64_t *max_asize,
224 uint64_t *ashift)
225 {
226 int numerrors = 0;
227 int lasterror = 0;
228
229 if (vd->vdev_children == 0) {
281 zio_t *pio;
282
283 mutex_enter(&zio->io_lock);
284 while ((pio = zio_walk_parents(zio)) != NULL) {
285 mutex_enter(&pio->io_lock);
286 ASSERT3U(zio->io_size, >=, pio->io_size);
287 bcopy(zio->io_data, pio->io_data, pio->io_size);
288 mutex_exit(&pio->io_lock);
289 }
290 mutex_exit(&zio->io_lock);
291 }
292
293 zio_buf_free(zio->io_data, zio->io_size);
294
295 mc->mc_error = zio->io_error;
296 mc->mc_tried = 1;
297 mc->mc_skipped = 0;
298 }
299
300 /*
301 * Check the other, lower-index DVAs to see if they're on the same
302 * vdev as the child we picked. If they are, use them since they
303 * are likely to have been allocated from the primary metaslab in
304 * use at the time, and hence are more likely to have locality with
305 * single-copy data.
306 */
307 static int
308 vdev_mirror_dva_select(zio_t *zio, int preferred)
309 {
310 dva_t *dva = zio->io_bp->blk_dva;
311 int c;
312
313 for (c = preferred - 1; c >= 0; c--) {
314 if (DVA_GET_VDEV(&dva[c]) == DVA_GET_VDEV(&dva[preferred]))
315 preferred = c;
316 }
317 return (preferred);
318 }
319
320 static int
321 vdev_mirror_preferred_child_randomize(zio_t *zio)
322 {
323 mirror_map_t *mm = zio->io_vsd;
324 int p;
325
326 if (mm->mm_root) {
327 p = spa_get_random(mm->mm_preferred_cnt);
328 return (vdev_mirror_dva_select(zio, mm->mm_preferred[p]));
329 }
330
331 /*
332 * To ensure we don't always favour the first matching vdev,
333 * which could lead to wear leveling issues on SSD's, we
334 * use the I/O offset as a pseudo random seed into the vdevs
335 * which have the lowest load.
336 */
337 p = (zio->io_offset >> zfs_vdev_mirror_shift) % mm->mm_preferred_cnt;
338 return (mm->mm_preferred[p]);
339 }
340
341 /*
342 * Try to find a vdev whose DTL doesn't contain the block we want to read
343 * prefering vdevs based on determined load.
344 *
345 * If we can't, try the read on any vdev we haven't already tried.
346 */
347 static int
348 vdev_mirror_child_select(zio_t *zio)
349 {
350 mirror_map_t *mm = zio->io_vsd;
351 uint64_t txg = zio->io_txg;
352 int c, lowest_load;
353
354 ASSERT(zio->io_bp == NULL || BP_PHYSICAL_BIRTH(zio->io_bp) == txg);
355
356 lowest_load = INT_MAX;
357 mm->mm_preferred_cnt = 0;
358 for (c = 0; c < mm->mm_children; c++) {
359 mirror_child_t *mc;
360
361 mc = &mm->mm_child[c];
362 if (mc->mc_tried || mc->mc_skipped)
363 continue;
364
365 if (!vdev_readable(mc->mc_vd)) {
366 mc->mc_error = SET_ERROR(ENXIO);
367 mc->mc_tried = 1; /* don't even try */
368 mc->mc_skipped = 1;
369 continue;
370 }
371
372 if (vdev_dtl_contains(mc->mc_vd, DTL_MISSING, txg, 1)) {
373 mc->mc_error = SET_ERROR(ESTALE);
374 mc->mc_skipped = 1;
375 mc->mc_speculative = 1;
376 continue;
377 }
378
379 mc->mc_load = vdev_mirror_load(mm, mc->mc_vd, mc->mc_offset);
380 if (mc->mc_load > lowest_load)
381 continue;
382
383 if (mc->mc_load < lowest_load) {
384 lowest_load = mc->mc_load;
385 mm->mm_preferred_cnt = 0;
386 }
387 mm->mm_preferred[mm->mm_preferred_cnt] = c;
388 mm->mm_preferred_cnt++;
389 }
390
391 if (mm->mm_preferred_cnt == 1) {
392 vdev_queue_register_last_queued_offset(
393 mm->mm_child[mm->mm_preferred[0]].mc_vd, zio);
394 return (mm->mm_preferred[0]);
395 }
396
397 if (mm->mm_preferred_cnt > 1) {
398 int c = vdev_mirror_preferred_child_randomize(zio);
399
400 vdev_queue_register_last_queued_offset(mm->mm_child[c].mc_vd,
401 zio);
402 return (c);
403 }
404
405 /*
406 * Every device is either missing or has this txg in its DTL.
407 * Look for any child we haven't already tried before giving up.
408 */
409 for (c = 0; c < mm->mm_children; c++) {
410 if (!mm->mm_child[c].mc_tried) {
411 vdev_queue_register_last_queued_offset(
412 mm->mm_child[c].mc_vd, zio);
413 return (c);
414 }
415 }
416
417 /*
418 * Every child failed. There's no place left to look.
419 */
420 return (-1);
421 }
422
423 static int
424 vdev_mirror_io_start(zio_t *zio)
425 {
426 mirror_map_t *mm;
427 mirror_child_t *mc;
428 int c, children;
429
430 mm = vdev_mirror_map_init(zio);
431
432 if (zio->io_type == ZIO_TYPE_READ) {
433 if ((zio->io_flags & ZIO_FLAG_SCRUB) && !mm->mm_replacing) {
434 /*
435 * For scrubbing reads we need to allocate a read
436 * buffer for each child and issue reads to all
437 * children. If any child succeeds, it will copy its
438 * data into zio->io_data in vdev_mirror_scrub_done.
439 */
440 for (c = 0; c < mm->mm_children; c++) {
441 mc = &mm->mm_child[c];
442 zio_nowait(zio_vdev_child_io(zio, zio->io_bp,
443 mc->mc_vd, mc->mc_offset,
444 zio_buf_alloc(zio->io_size), zio->io_size,
445 zio->io_type, zio->io_priority, 0,
446 vdev_mirror_scrub_done, mc));
447 }
448 return (ZIO_PIPELINE_CONTINUE);
449 }
450 /*
|