The function find_cgroup_mnt() could be called under multithread scenario, so
we should use the reentrant edition getmntent_r() instead of getmntent().
E.g, without this fix the output for below job file is wrong.
[root@localhost blkio-test]# cat small-read-file
[global]
ioengine=sync
direct=1
rw=read
bs=4k
filename=/dev/sdb
time_based
runtime=60
cgroup=small
cgroup_weight=500
numjobs=32
group_reporting
thread
[file1]
Then fio randomly says:
[cut here]
Starting 32 threads
fio: cgroup blkio does not appear to be mounted
fio: cgroup blkio does not appear to be mounted
fio: cgroup blkio does not appear to be mounted
---
cgroup.c | 5 +++--
1 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/cgroup.c b/cgroup.c
index f36683a..4f02ecd 100644
--- a/cgroup.c
+++ b/cgroup.c
@@ -22,7 +22,8 @@ struct cgroup_member {
static char *find_cgroup_mnt(struct thread_data *td)
{
char *mntpoint = NULL;
- struct mntent *mnt;
+ struct mntent *mnt, dummy;
+ char buf[256] = {0};
FILE *f;
f = setmntent("/proc/mounts", "r");
@@ -31,7 +32,7 @@ static char *find_cgroup_mnt(struct thread_data *td)
return NULL;
}
- while ((mnt = getmntent(f)) != NULL) {
+ while ((mnt = getmntent_r(f, &dummy, buf, 256)) != NULL) {
if (!strcmp(mnt->mnt_type, "cgroup") &&
strstr(mnt->mnt_opts, "blkio"))
break;
--
1.7.4.4
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