summaryrefslogtreecommitdiffstats
path: root/net/ceph/striper.c
blob: c36462dc86b721e9ccd8f53b9b2419520110e76a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
/* SPDX-License-Identifier: GPL-2.0 */

#include <linux/ceph/ceph_debug.h>

#include <linux/math64.h>
#include <linux/slab.h>

#include <linux/ceph/striper.h>
#include <linux/ceph/types.h>

/*
 * Map a file extent to a stripe unit within an object.
 * Fill in objno, offset into object, and object extent length (i.e. the
 * number of bytes mapped, less than or equal to @l->stripe_unit).
 *
 * Example for stripe_count = 3, stripes_per_object = 4:
 *
 * blockno   |  0  3  6  9 |  1  4  7 10 |  2  5  8 11 | 12 15 18 21 | 13 16 19
 * stripeno  |  0  1  2  3 |  0  1  2  3 |  0  1  2  3 |  4  5  6  7 |  4  5  6
 * stripepos |      0      |      1      |      2      |      0      |      1
 * objno     |      0      |      1      |      2      |      3      |      4
 * objsetno  |                    0                    |                    1
 */
void ceph_calc_file_object_mapping(struct ceph_file_layout *l,
				   u64 off, u64 len,
				   u64 *objno, u64 *objoff, u32 *xlen)
{
	u32 stripes_per_object = l->object_size / l->stripe_unit;
	u64 blockno;	/* which su in the file (i.e. globally) */
	u32 blockoff;	/* offset into su */
	u64 stripeno;	/* which stripe */
	u32 stripepos;	/* which su in the stripe,
			   which object in the object set */
	u64 objsetno;	/* which object set */
	u32 objsetpos;	/* which stripe in the object set */

	blockno = div_u64_rem(off, l->stripe_unit, &blockoff);
	stripeno = div_u64_rem(blockno, l->stripe_count, &stripepos);
	objsetno = div_u64_rem(stripeno, stripes_per_object, &objsetpos);

	*objno = objsetno * l->stripe_count + stripepos;
	*objoff = objsetpos * l->stripe_unit + blockoff;
	*xlen = min_t(u64, len, l->stripe_unit - blockoff);
}
EXPORT_SYMBOL(ceph_calc_file_object_mapping);

/*
 * Return the last extent with given objno (@object_extents is sorted
 * by objno).  If not found, return NULL and set @add_pos so that the
 * new extent can be added with list_add(add_pos, new_ex).
 */
static struct ceph_object_extent *
lookup_last(struct list_head *object_extents, u64 objno,
	    struct list_head **add_pos)
{
	struct list_head *pos;

	list_for_each_prev(pos, object_extents) {
		struct ceph_object_extent *ex =
		    list_entry(pos, typeof(*ex), oe_item);

		if (ex->oe_objno == objno)
			return ex;

		if (ex->oe_objno < objno)
			break;
	}

	*add_pos = pos;
	return NULL;
}

static struct ceph_object_extent *
lookup_containing(struct list_head *object_extents, u64 objno,
		  u64 objoff, u32 xlen)
{
	struct ceph_object_extent *ex;

	list_for_each_entry(ex, object_extents, oe_item) {
		if (ex->oe_objno == objno &&
		    ex->oe_off <= objoff &&
		    ex->oe_off + ex->oe_len >= objoff + xlen) /* paranoia */
			return ex;

		if (ex->oe_objno > objno)
			break;
	}

	return NULL;
}

/*
 * Map a file extent to a sorted list of object extents.
 *
 * We want only one (or as few as possible) object extents per object.
 * Adjacent object extents will be merged together, each returned object
 * extent may reverse map to multiple different file extents.
 *
 * Call @alloc_fn for each new object extent and @action_fn for each
 * mapped stripe unit, whether it was merged into an already allocated
 * object extent or started a new object extent.
 *
 * Newly allocated object extents are added to @object_extents.
 * To keep @object_extents sorted, successive calls to this function
 * must map successive file extents (i.e. the list of file extents that
 * are mapped using the same @object_extents must be sorted).
 *
 * The caller is responsible for @object_extents.
 */
int ceph_file_to_extents(struct ceph_file_layout *l, u64 off, u64 len,
			 struct list_head *object_extents,
			 struct ceph_object_extent *alloc_fn(void *arg),
			 void *alloc_arg,
			 ceph_object_extent_fn_t action_fn,
			 void *action_arg)
{
	struct ceph_object_extent *last_ex, *ex;

	while (len) {
		struct list_head *add_pos = NULL;
		u64 objno, objoff;
		u32 xlen;

		ceph_calc_file_object_mapping(l, off, len, &objno, &objoff,
					      &xlen);

		last_ex = lookup_last(object_extents, objno, &add_pos);
		if (!last_ex || last_ex->oe_off + last_ex->oe_len != objoff) {
			ex = alloc_fn(alloc_arg);
			if (!ex)
				return -ENOMEM;

			ex->oe_objno = objno;
			ex->oe_off = objoff;
			ex->oe_len = xlen;
			if (action_fn)
				action_fn(ex, xlen, action_arg);

			if (!last_ex)
				list_add(&ex->oe_item, add_pos);
			else
				list_add(&ex->oe_item, &last_ex->oe_item);
		} else {
			last_ex->oe_len += xlen;
			if (action_fn)
				action_fn(last_ex, xlen, action_arg);
		}

		off += xlen;
		len -= xlen;
	}

	for (last_ex = list_first_entry(object_extents, typeof(*ex), oe_item),
	     ex = list_next_entry(last_ex, oe_item);
	     &ex->oe_item != object_extents;
	     last_ex = ex, ex = list_next_entry(ex, oe_item)) {
		if (last_ex->oe_objno > ex->oe_objno ||
		    (last_ex->oe_objno == ex->oe_objno &&
		     last_ex->oe_off + last_ex->oe_len >= ex->oe_off)) {
			WARN(1, "%s: object_extents list not sorted!\n",
			     __func__);
			return -EINVAL;
		}
	}

	return 0;
}
EXPORT_SYMBOL(ceph_file_to_extents);

/*
 * A stripped down, non-allocating version of ceph_file_to_extents(),
 * for when @object_extents is already populated.
 */
int ceph_iterate_extents(struct ceph_file_layout *l, u64 off, u64 len,
			 struct list_head *object_extents,
			 ceph_object_extent_fn_t action_fn,
			 void *action_arg)
{
	while (len) {
		struct ceph_object_extent *ex;
		u64 objno, objoff;
		u32 xlen;

		ceph_calc_file_object_mapping(l, off, len, &objno, &objoff,
					      &xlen);

		ex = lookup_containing(object_extents, objno, objoff, xlen);
		if (!ex) {
			WARN(1, "%s: objno %llu %llu~%u not found!\n",
			     __func__, objno, objoff, xlen);
			return -EINVAL;
		}

		action_fn(ex, xlen, action_arg);

		off += xlen;
		len -= xlen;
	}

	return 0;
}
EXPORT_SYMBOL(ceph_iterate_extents);

/*
 * Reverse map an object extent to a sorted list of file extents.
 *
 * On success, the caller is responsible for:
 *
 *     kfree(file_extents)
 */
int ceph_extent_to_file(struct ceph_file_layout *l,
			u64 objno, u64 objoff, u64 objlen,
			struct ceph_file_extent **file_extents,
			u32 *num_file_extents)
{
	u32 stripes_per_object = l->object_size / l->stripe_unit;
	u64 blockno;	/* which su */
	u32 blockoff;	/* offset into su */
	u64 stripeno;	/* which stripe */
	u32 stripepos;	/* which su in the stripe,
			   which object in the object set */
	u64 objsetno;	/* which object set */
	u32 i = 0;

	if (!objlen) {
		*file_extents = NULL;
		*num_file_extents = 0;
		return 0;
	}

	*num_file_extents = DIV_ROUND_UP_ULL(objoff + objlen, l->stripe_unit) -
				     DIV_ROUND_DOWN_ULL(objoff, l->stripe_unit);
	*file_extents = kmalloc_array(*num_file_extents, sizeof(**file_extents),
				      GFP_NOIO);
	if (!*file_extents)
		return -ENOMEM;

	div_u64_rem(objoff, l->stripe_unit, &blockoff);
	while (objlen) {
		u64 off, len;

		objsetno = div_u64_rem(objno, l->stripe_count, &stripepos);
		stripeno = div_u64(objoff, l->stripe_unit) +
						objsetno * stripes_per_object;
		blockno = stripeno * l->stripe_count + stripepos;
		off = blockno * l->stripe_unit + blockoff;
		len = min_t(u64, objlen, l->stripe_unit - blockoff);

		(*file_extents)[i].fe_off = off;
		(*file_extents)[i].fe_len = len;

		blockoff = 0;
		objoff += len;
		objlen -= len;
		i++;
	}

	BUG_ON(i != *num_file_extents);
	return 0;
}
EXPORT_SYMBOL(ceph_extent_to_file);