Btrfs was using normal srand()/rand() pseudo-random number generator
functions.
Although it's mostly fine, but it's quite easy to forget to initialize
the seed.
This patch will introduce new random number generator wrappers:
rand_int(), rand_u8/16/32/64(), and use uniformly distributed
pseudo-random number generator as backend.
The new wrappers will always set new seed based on time and pid/ppid to
avoid manually setting for seed.
Suggested-by: David Sterba <dsterba@xxxxxxx>
Signed-off-by: Qu Wenruo <quwenruo@xxxxxxxxxxxxxx>
---
btrfs-corrupt-block.c | 23 +++++++++++------------
btrfs-image.c | 4 ++--
dir-test.c | 8 ++++----
quick-test.c | 7 +------
utils.c | 20 ++++++++++++++++++++
utils.h | 26 ++++++++++++++++++++++++++
6 files changed, 64 insertions(+), 24 deletions(-)
diff --git a/btrfs-corrupt-block.c b/btrfs-corrupt-block.c
index d331f96..c7c4490 100644
--- a/btrfs-corrupt-block.c
+++ b/btrfs-corrupt-block.c
@@ -131,8 +131,8 @@ static void corrupt_keys(struct btrfs_trans_handle *trans,
if (nr == 0)
return;
- slot = rand() % nr;
- bad_slot = rand() % nr;
+ slot = rand_int() % nr;
+ bad_slot = rand_int() % nr;
if (bad_slot == slot)
return;
@@ -181,7 +181,7 @@ static int corrupt_extent(struct btrfs_trans_handle *trans,
struct btrfs_path *path;
int ret;
int slot;
- int should_del = rand() % 3;
+ int should_del = rand_int() % 3;
path = btrfs_alloc_path();
if (!path)
@@ -257,7 +257,7 @@ static void btrfs_corrupt_extent_leaf(struct btrfs_trans_handle *trans,
struct extent_buffer *eb)
{
u32 nr = btrfs_header_nritems(eb);
- u32 victim = rand() % nr;
+ u32 victim = rand_u32() % nr;
u64 objectid;
struct btrfs_key key;
@@ -281,7 +281,7 @@ static void btrfs_corrupt_extent_tree(struct btrfs_trans_handle *trans,
}
if (btrfs_header_level(eb) == 1 && eb != root->node) {
- if (rand() % 5)
+ if (rand_int() % 5)
return;
}
@@ -390,7 +390,7 @@ static u64 generate_u64(u64 orig)
{
u64 ret;
do {
- ret = rand();
+ ret = rand_u64();
} while (ret == orig);
return ret;
}
@@ -399,7 +399,7 @@ static u32 generate_u32(u32 orig)
{
u32 ret;
do {
- ret = rand();
+ ret = rand_u32();
} while (ret == orig);
return ret;
}
@@ -408,7 +408,7 @@ static u8 generate_u8(u8 orig)
{
u8 ret;
do {
- ret = rand();
+ ret = rand_u8();
} while (ret == orig);
return ret;
}
@@ -944,7 +944,7 @@ static int corrupt_chunk_tree(struct btrfs_trans_handle *trans,
while (!btrfs_previous_item(root, path, 0, BTRFS_DEV_ITEM_KEY)) {
slot = path->slots[0];
leaf = path->nodes[0];
- del = rand() % 3;
+ del = rand_int() % 3;
/* Never delete the first item to keep the leaf structure */
if (path->slots[0] == 0)
del = 0;
@@ -971,7 +971,7 @@ static int corrupt_chunk_tree(struct btrfs_trans_handle *trans,
while (!btrfs_previous_item(root, path, 0, BTRFS_CHUNK_ITEM_KEY)) {
slot = path->slots[0];
leaf = path->nodes[0];
- del = rand() % 3;
+ del = rand_int() % 3;
btrfs_item_key_to_cpu(leaf, &found_key, slot);
ret = corrupt_item_nocow(trans, root, path, del);
if (ret)
@@ -1040,7 +1040,6 @@ int main(int argc, char **argv)
char field[FIELD_BUF_LEN];
field[0] = '\0';
- srand(128);
memset(&key, 0, sizeof(key));
while(1) {
@@ -1179,7 +1178,7 @@ int main(int argc, char **argv)
if (logical == (u64)-1)
print_usage(1);
- del = rand() % 3;
+ del = rand_int() % 3;
path = btrfs_alloc_path();
if (!path) {
fprintf(stderr, "path allocation failed\n");
diff --git a/btrfs-image.c b/btrfs-image.c
index 8a1b799..42e3781 100644
--- a/btrfs-image.c
+++ b/btrfs-image.c
@@ -188,7 +188,7 @@ static char *generate_garbage(u32 name_len)
return NULL;
for (i = 0; i < name_len; i++) {
- char c = rand() % 94 + 33;
+ char c = rand_int() % 94 + 33;
if (c == '/')
c++;
@@ -392,7 +392,7 @@ static char *find_collision(struct metadump_struct *md, char *name,
"generating normal garbage, it won't match indexes\n",
val->len, val->val);
for (i = 0; i < name_len; i++) {
- char c = rand() % 94 + 33;
+ char c = rand_int() % 94 + 33;
if (c == '/')
c++;
diff --git a/dir-test.c b/dir-test.c
index a54b777..ae37b66 100644
--- a/dir-test.c
+++ b/dir-test.c
@@ -38,7 +38,7 @@ static u64 file_oid = 33778;
static int find_num(struct radix_tree_root *root, unsigned long *num_ret,
int exists)
{
- unsigned long num = rand();
+ unsigned long num = rand_u32();
unsigned long res[2];
int ret;
@@ -384,7 +384,7 @@ static int bulk_op(struct btrfs_trans_handle *trans, struct btrfs_root *root,
struct radix_tree_root *radix)
{
int ret;
- int nr = rand() % 5000;
+ int nr = rand_int() % 5000;
static int run_nr = 0;
/* do the bulk op much less frequently */
@@ -473,8 +473,8 @@ int main(int ac, char **av)
goto out;
}
for (i = 0; i < iterations; i++) {
- op = rand() % ARRAY_SIZE(ops);
- count = rand() % 128;
+ op = rand_int() % ARRAY_SIZE(ops);
+ count = rand_int() % 128;
if (i % 2000 == 0) {
printf("%d\n", i);
fflush(stdout);
diff --git a/quick-test.c b/quick-test.c
index ffde85d..b6dec5a 100644
--- a/quick-test.c
+++ b/quick-test.c
@@ -28,7 +28,7 @@
/* for testing only */
static int next_key(int i, int max_key) {
- return rand() % max_key;
+ return rand_int() % max_key;
// return i;
}
@@ -56,7 +56,6 @@ int main(int ac, char **av) {
exit(1);
}
trans = btrfs_start_transaction(root, 1);
- srand(55);
btrfs_set_key_type(&ins, BTRFS_STRING_ITEM_KEY);
for (i = 0; i < run_size; i++) {
num = next_key(i, max_key);
@@ -83,7 +82,6 @@ int main(int ac, char **av) {
exit(1);
}
printf("starting search\n");
- srand(55);
for (i = 0; i < run_size; i++) {
num = next_key(i, max_key);
ins.objectid = num;
@@ -112,7 +110,6 @@ int main(int ac, char **av) {
btrfs_header_nritems(root->node));
printf("all searches good, deleting some items\n");
i = 0;
- srand(55);
trans = btrfs_start_transaction(root, 1);
for (i = 0 ; i < run_size/4; i++) {
num = next_key(i, max_key);
@@ -138,7 +135,6 @@ int main(int ac, char **av) {
exit(1);
}
trans = btrfs_start_transaction(root, 1);
- srand(128);
for (i = 0; i < run_size; i++) {
num = next_key(i, max_key);
sprintf(buf, "string-%d", num);
@@ -157,7 +153,6 @@ int main(int ac, char **av) {
fprintf(stderr, "Open ctree failed\n");
exit(1);
}
- srand(128);
printf("starting search2\n");
for (i = 0; i < run_size; i++) {
num = next_key(i, max_key);
diff --git a/utils.c b/utils.c
index 68a5af4..805fa48 100644
--- a/utils.c
+++ b/utils.c
@@ -4064,3 +4064,23 @@ out:
return ret;
}
+
+u32 rand_u32(void)
+{
+ struct timeval tv;
+ unsigned short rand_seed[3];
+ long int ret;
+ int i;
+
+ gettimeofday(&tv, 0);
+ rand_seed[0] = getpid() ^ (tv.tv_sec & 0xFFFF);
+ rand_seed[1] = getppid() ^ (tv.tv_usec & 0xFFFF);
+ rand_seed[2] = (tv.tv_sec ^ tv.tv_usec) >> 16;
+
+ /* Crank the random number generator a few times */
+ gettimeofday(&tv, 0);
+ for (i = (tv.tv_sec ^ tv.tv_sec) ^ 0x1F; i > 0; i--)
+ nrand48(rand_seed);
+ ret = nrand48(rand_seed);
+ return (u32)ret;
+}
diff --git a/utils.h b/utils.h
index ebe6d61..6a00871 100644
--- a/utils.h
+++ b/utils.h
@@ -362,4 +362,30 @@ static inline int error_on(int condition, const char *fmt, ...)
return 1;
}
+/*
+ * Random number generator wrappers
+ * Caller has no need to set seed, as all function will set seed based on
+ * pid/ppid and current time
+ */
+u32 rand_u32(void);
+static inline int rand_int(void)
+{
+ return (int)(rand_u32());
+}
+static inline u8 rand_u8(void)
+{
+ return (u8)(rand_u32());
+}
+static inline u16 rand_u16(void)
+{
+ return (u16)(rand_u32());
+}
+static inline u64 rand_u64(void)
+{
+ u64 ret = 0;
+ ret += rand_u32();
+ ret = ret << 32;
+ ret += rand_u32();
+ return ret;
+}
#endif
--
2.8.2
--
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