On 2011-11-22 07:56, Zhu Yanhai wrote:
> 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;
Thanks applied, with a small change to use sizeof(buf) instead of 256 in
both places.
--
Jens Axboe
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