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Commit a84cd29335f4ca38ca8405c1636ee3876bb292b5

Authored by Sam Lang
Committed by Sage Weil
1 parent 8b3e1a5698
Exists in smarc-l5.0.0_1.0.0-ga and in 5 other branches imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga

ceph: Use pseudo-random numbers to choose mds 

We don't need to use up entropy to choose an mds,
so use prandom_u32() to get a pseudo-random number.

Also, we don't need to choose a random mds if only
one mds is available, so add special casing for the
common case.

Fixes http://tracker.ceph.com/issues/3579

Signed-off-by: Sam Lang <sam.lang@inktank.com>
Reviewed-by: Greg Farnum <greg@inktank.com>
Reviewed-by: Alex Elder <elder@inktank.com>

Showing 1 changed file with 5 additions and 3 deletions Inline Diff

1 #include <linux/ceph/ceph_debug.h> 1 #include <linux/ceph/ceph_debug.h>
2 2
3 #include <linux/bug.h> 3 #include <linux/bug.h>
4 #include <linux/err.h> 4 #include <linux/err.h>
5 #include <linux/random.h> 5 #include <linux/random.h>
6 #include <linux/slab.h> 6 #include <linux/slab.h>
7 #include <linux/types.h> 7 #include <linux/types.h>
8 8
9 #include <linux/ceph/mdsmap.h> 9 #include <linux/ceph/mdsmap.h>
10 #include <linux/ceph/messenger.h> 10 #include <linux/ceph/messenger.h>
11 #include <linux/ceph/decode.h> 11 #include <linux/ceph/decode.h>
12 12
13 #include "super.h" 13 #include "super.h"
14 14
15 15
16 /* 16 /*
17 * choose a random mds that is "up" (i.e. has a state > 0), or -1. 17 * choose a random mds that is "up" (i.e. has a state > 0), or -1.
18 */ 18 */
19 int ceph_mdsmap_get_random_mds(struct ceph_mdsmap *m) 19 int ceph_mdsmap_get_random_mds(struct ceph_mdsmap *m)
20 { 20 {
21 int n = 0; 21 int n = 0;
22 int i; 22 int i;
23 char r;
24 23
24 /* special case for one mds */
25 if (1 == m->m_max_mds && m->m_info[0].state > 0)
26 return 0;
27
25 /* count */ 28 /* count */
26 for (i = 0; i < m->m_max_mds; i++) 29 for (i = 0; i < m->m_max_mds; i++)
27 if (m->m_info[i].state > 0) 30 if (m->m_info[i].state > 0)
28 n++; 31 n++;
29 if (n == 0) 32 if (n == 0)
30 return -1; 33 return -1;
31 34
32 /* pick */ 35 /* pick */
33 get_random_bytes(&r, 1); 36 n = prandom_u32() % n;
34 n = r % n;
35 i = 0; 37 i = 0;
36 for (i = 0; n > 0; i++, n--) 38 for (i = 0; n > 0; i++, n--)
37 while (m->m_info[i].state <= 0) 39 while (m->m_info[i].state <= 0)
38 i++; 40 i++;
39 41
40 return i; 42 return i;
41 } 43 }
42 44
43 /* 45 /*
44 * Decode an MDS map 46 * Decode an MDS map
45 * 47 *
46 * Ignore any fields we don't care about (there are quite a few of 48 * Ignore any fields we don't care about (there are quite a few of
47 * them). 49 * them).
48 */ 50 */
49 struct ceph_mdsmap *ceph_mdsmap_decode(void **p, void *end) 51 struct ceph_mdsmap *ceph_mdsmap_decode(void **p, void *end)
50 { 52 {
51 struct ceph_mdsmap *m; 53 struct ceph_mdsmap *m;
52 const void *start = *p; 54 const void *start = *p;
53 int i, j, n; 55 int i, j, n;
54 int err = -EINVAL; 56 int err = -EINVAL;
55 u16 version; 57 u16 version;
56 58
57 m = kzalloc(sizeof(*m), GFP_NOFS); 59 m = kzalloc(sizeof(*m), GFP_NOFS);
58 if (m == NULL) 60 if (m == NULL)
59 return ERR_PTR(-ENOMEM); 61 return ERR_PTR(-ENOMEM);
60 62
61 ceph_decode_16_safe(p, end, version, bad); 63 ceph_decode_16_safe(p, end, version, bad);
62 if (version > 3) { 64 if (version > 3) {
63 pr_warning("got mdsmap version %d > 3, failing", version); 65 pr_warning("got mdsmap version %d > 3, failing", version);
64 goto bad; 66 goto bad;
65 } 67 }
66 68
67 ceph_decode_need(p, end, 8*sizeof(u32) + sizeof(u64), bad); 69 ceph_decode_need(p, end, 8*sizeof(u32) + sizeof(u64), bad);
68 m->m_epoch = ceph_decode_32(p); 70 m->m_epoch = ceph_decode_32(p);
69 m->m_client_epoch = ceph_decode_32(p); 71 m->m_client_epoch = ceph_decode_32(p);
70 m->m_last_failure = ceph_decode_32(p); 72 m->m_last_failure = ceph_decode_32(p);
71 m->m_root = ceph_decode_32(p); 73 m->m_root = ceph_decode_32(p);
72 m->m_session_timeout = ceph_decode_32(p); 74 m->m_session_timeout = ceph_decode_32(p);
73 m->m_session_autoclose = ceph_decode_32(p); 75 m->m_session_autoclose = ceph_decode_32(p);
74 m->m_max_file_size = ceph_decode_64(p); 76 m->m_max_file_size = ceph_decode_64(p);
75 m->m_max_mds = ceph_decode_32(p); 77 m->m_max_mds = ceph_decode_32(p);
76 78
77 m->m_info = kcalloc(m->m_max_mds, sizeof(*m->m_info), GFP_NOFS); 79 m->m_info = kcalloc(m->m_max_mds, sizeof(*m->m_info), GFP_NOFS);
78 if (m->m_info == NULL) 80 if (m->m_info == NULL)
79 goto badmem; 81 goto badmem;
80 82
81 /* pick out active nodes from mds_info (state > 0) */ 83 /* pick out active nodes from mds_info (state > 0) */
82 n = ceph_decode_32(p); 84 n = ceph_decode_32(p);
83 for (i = 0; i < n; i++) { 85 for (i = 0; i < n; i++) {
84 u64 global_id; 86 u64 global_id;
85 u32 namelen; 87 u32 namelen;
86 s32 mds, inc, state; 88 s32 mds, inc, state;
87 u64 state_seq; 89 u64 state_seq;
88 u8 infoversion; 90 u8 infoversion;
89 struct ceph_entity_addr addr; 91 struct ceph_entity_addr addr;
90 u32 num_export_targets; 92 u32 num_export_targets;
91 void *pexport_targets = NULL; 93 void *pexport_targets = NULL;
92 struct ceph_timespec laggy_since; 94 struct ceph_timespec laggy_since;
93 95
94 ceph_decode_need(p, end, sizeof(u64)*2 + 1 + sizeof(u32), bad); 96 ceph_decode_need(p, end, sizeof(u64)*2 + 1 + sizeof(u32), bad);
95 global_id = ceph_decode_64(p); 97 global_id = ceph_decode_64(p);
96 infoversion = ceph_decode_8(p); 98 infoversion = ceph_decode_8(p);
97 *p += sizeof(u64); 99 *p += sizeof(u64);
98 namelen = ceph_decode_32(p); /* skip mds name */ 100 namelen = ceph_decode_32(p); /* skip mds name */
99 *p += namelen; 101 *p += namelen;
100 102
101 ceph_decode_need(p, end, 103 ceph_decode_need(p, end,
102 4*sizeof(u32) + sizeof(u64) + 104 4*sizeof(u32) + sizeof(u64) +
103 sizeof(addr) + sizeof(struct ceph_timespec), 105 sizeof(addr) + sizeof(struct ceph_timespec),
104 bad); 106 bad);
105 mds = ceph_decode_32(p); 107 mds = ceph_decode_32(p);
106 inc = ceph_decode_32(p); 108 inc = ceph_decode_32(p);
107 state = ceph_decode_32(p); 109 state = ceph_decode_32(p);
108 state_seq = ceph_decode_64(p); 110 state_seq = ceph_decode_64(p);
109 ceph_decode_copy(p, &addr, sizeof(addr)); 111 ceph_decode_copy(p, &addr, sizeof(addr));
110 ceph_decode_addr(&addr); 112 ceph_decode_addr(&addr);
111 ceph_decode_copy(p, &laggy_since, sizeof(laggy_since)); 113 ceph_decode_copy(p, &laggy_since, sizeof(laggy_since));
112 *p += sizeof(u32); 114 *p += sizeof(u32);
113 ceph_decode_32_safe(p, end, namelen, bad); 115 ceph_decode_32_safe(p, end, namelen, bad);
114 *p += namelen; 116 *p += namelen;
115 if (infoversion >= 2) { 117 if (infoversion >= 2) {
116 ceph_decode_32_safe(p, end, num_export_targets, bad); 118 ceph_decode_32_safe(p, end, num_export_targets, bad);
117 pexport_targets = *p; 119 pexport_targets = *p;
118 *p += num_export_targets * sizeof(u32); 120 *p += num_export_targets * sizeof(u32);
119 } else { 121 } else {
120 num_export_targets = 0; 122 num_export_targets = 0;
121 } 123 }
122 124
123 dout("mdsmap_decode %d/%d %lld mds%d.%d %s %s\n", 125 dout("mdsmap_decode %d/%d %lld mds%d.%d %s %s\n",
124 i+1, n, global_id, mds, inc, 126 i+1, n, global_id, mds, inc,
125 ceph_pr_addr(&addr.in_addr), 127 ceph_pr_addr(&addr.in_addr),
126 ceph_mds_state_name(state)); 128 ceph_mds_state_name(state));
127 if (mds >= 0 && mds < m->m_max_mds && state > 0) { 129 if (mds >= 0 && mds < m->m_max_mds && state > 0) {
128 m->m_info[mds].global_id = global_id; 130 m->m_info[mds].global_id = global_id;
129 m->m_info[mds].state = state; 131 m->m_info[mds].state = state;
130 m->m_info[mds].addr = addr; 132 m->m_info[mds].addr = addr;
131 m->m_info[mds].laggy = 133 m->m_info[mds].laggy =
132 (laggy_since.tv_sec != 0 || 134 (laggy_since.tv_sec != 0 ||
133 laggy_since.tv_nsec != 0); 135 laggy_since.tv_nsec != 0);
134 m->m_info[mds].num_export_targets = num_export_targets; 136 m->m_info[mds].num_export_targets = num_export_targets;
135 if (num_export_targets) { 137 if (num_export_targets) {
136 m->m_info[mds].export_targets = 138 m->m_info[mds].export_targets =
137 kcalloc(num_export_targets, sizeof(u32), 139 kcalloc(num_export_targets, sizeof(u32),
138 GFP_NOFS); 140 GFP_NOFS);
139 for (j = 0; j < num_export_targets; j++) 141 for (j = 0; j < num_export_targets; j++)
140 m->m_info[mds].export_targets[j] = 142 m->m_info[mds].export_targets[j] =
141 ceph_decode_32(&pexport_targets); 143 ceph_decode_32(&pexport_targets);
142 } else { 144 } else {
143 m->m_info[mds].export_targets = NULL; 145 m->m_info[mds].export_targets = NULL;
144 } 146 }
145 } 147 }
146 } 148 }
147 149
148 /* pg_pools */ 150 /* pg_pools */
149 ceph_decode_32_safe(p, end, n, bad); 151 ceph_decode_32_safe(p, end, n, bad);
150 m->m_num_data_pg_pools = n; 152 m->m_num_data_pg_pools = n;
151 m->m_data_pg_pools = kcalloc(n, sizeof(u64), GFP_NOFS); 153 m->m_data_pg_pools = kcalloc(n, sizeof(u64), GFP_NOFS);
152 if (!m->m_data_pg_pools) 154 if (!m->m_data_pg_pools)
153 goto badmem; 155 goto badmem;
154 ceph_decode_need(p, end, sizeof(u64)*(n+1), bad); 156 ceph_decode_need(p, end, sizeof(u64)*(n+1), bad);
155 for (i = 0; i < n; i++) 157 for (i = 0; i < n; i++)
156 m->m_data_pg_pools[i] = ceph_decode_64(p); 158 m->m_data_pg_pools[i] = ceph_decode_64(p);
157 m->m_cas_pg_pool = ceph_decode_64(p); 159 m->m_cas_pg_pool = ceph_decode_64(p);
158 160
159 /* ok, we don't care about the rest. */ 161 /* ok, we don't care about the rest. */
160 dout("mdsmap_decode success epoch %u\n", m->m_epoch); 162 dout("mdsmap_decode success epoch %u\n", m->m_epoch);
161 return m; 163 return m;
162 164
163 badmem: 165 badmem:
164 err = -ENOMEM; 166 err = -ENOMEM;
165 bad: 167 bad:
166 pr_err("corrupt mdsmap\n"); 168 pr_err("corrupt mdsmap\n");
167 print_hex_dump(KERN_DEBUG, "mdsmap: ", 169 print_hex_dump(KERN_DEBUG, "mdsmap: ",
168 DUMP_PREFIX_OFFSET, 16, 1, 170 DUMP_PREFIX_OFFSET, 16, 1,
169 start, end - start, true); 171 start, end - start, true);
170 ceph_mdsmap_destroy(m); 172 ceph_mdsmap_destroy(m);
171 return ERR_PTR(-EINVAL); 173 return ERR_PTR(-EINVAL);
172 } 174 }
173 175
174 void ceph_mdsmap_destroy(struct ceph_mdsmap *m) 176 void ceph_mdsmap_destroy(struct ceph_mdsmap *m)
175 { 177 {
176 int i; 178 int i;
177 179
178 for (i = 0; i < m->m_max_mds; i++) 180 for (i = 0; i < m->m_max_mds; i++)
179 kfree(m->m_info[i].export_targets); 181 kfree(m->m_info[i].export_targets);
180 kfree(m->m_info); 182 kfree(m->m_info);
181 kfree(m->m_data_pg_pools); 183 kfree(m->m_data_pg_pools);
182 kfree(m); 184 kfree(m);