bcache: fix a spurious gcc complaint, use scnprintf
An old version of gcc was complaining about using a const int as the
size of a stack allocated array. Which should be fine - but using
ARRAY_SIZE() is better, anyways.
Also, refactor the code to use scnprintf().
Signed-off-by: Kent Overstreet <koverstreet@google.com>
diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
index 4d9cca4..29228b8 100644
--- a/drivers/md/bcache/sysfs.c
+++ b/drivers/md/bcache/sysfs.c
@@ -665,12 +665,10 @@
int cmp(const void *l, const void *r)
{ return *((uint16_t *) r) - *((uint16_t *) l); }
- /* Number of quantiles we compute */
- const unsigned nq = 31;
-
size_t n = ca->sb.nbuckets, i, unused, btree;
uint64_t sum = 0;
- uint16_t q[nq], *p, *cached;
+ /* Compute 31 quantiles */
+ uint16_t q[31], *p, *cached;
ssize_t ret;
cached = p = vmalloc(ca->sb.nbuckets * sizeof(uint16_t));
@@ -703,26 +701,29 @@
if (n)
do_div(sum, n);
- for (i = 0; i < nq; i++)
- q[i] = INITIAL_PRIO - cached[n * (i + 1) / (nq + 1)];
+ for (i = 0; i < ARRAY_SIZE(q); i++)
+ q[i] = INITIAL_PRIO - cached[n * (i + 1) /
+ (ARRAY_SIZE(q) + 1)];
vfree(p);
- ret = snprintf(buf, PAGE_SIZE,
- "Unused: %zu%%\n"
- "Metadata: %zu%%\n"
- "Average: %llu\n"
- "Sectors per Q: %zu\n"
- "Quantiles: [",
- unused * 100 / (size_t) ca->sb.nbuckets,
- btree * 100 / (size_t) ca->sb.nbuckets, sum,
- n * ca->sb.bucket_size / (nq + 1));
+ ret = scnprintf(buf, PAGE_SIZE,
+ "Unused: %zu%%\n"
+ "Metadata: %zu%%\n"
+ "Average: %llu\n"
+ "Sectors per Q: %zu\n"
+ "Quantiles: [",
+ unused * 100 / (size_t) ca->sb.nbuckets,
+ btree * 100 / (size_t) ca->sb.nbuckets, sum,
+ n * ca->sb.bucket_size / (ARRAY_SIZE(q) + 1));
- for (i = 0; i < nq && ret < (ssize_t) PAGE_SIZE; i++)
- ret += snprintf(buf + ret, PAGE_SIZE - ret,
- i < nq - 1 ? "%u " : "%u]\n", q[i]);
+ for (i = 0; i < ARRAY_SIZE(q); i++)
+ ret += scnprintf(buf + ret, PAGE_SIZE - ret,
+ "%u ", q[i]);
+ ret--;
- buf[PAGE_SIZE - 1] = '\0';
+ ret += scnprintf(buf + ret, PAGE_SIZE - ret, "]\n");
+
return ret;
}