Autodetect cgroup blkio mount point

[fio.git] / cgroup.c

diff --git a/cgroup.c b/cgroup.c
index b65b1fb8d7e6a08e834223eab1c6675d7e6a1df3..14bbc57bd0862a46cac3ea0fbd9162288c77341f 100644 (file)
--- a/cgroup.c
+++ b/cgroup.c
@@ -3,6 +3,7 @@
  */
 #include <stdio.h>
 #include <stdlib.h>
+#include <mntent.h>
 #include "fio.h"
 #include "flist.h"
 #include "cgroup.h"
@@ -15,6 +16,33 @@ struct cgroup_member {
        char *root;
 };
 
+static char *find_cgroup_mnt(struct thread_data *td)
+{
+       char *mntpoint = NULL;
+       struct mntent *mnt;
+       FILE *f;
+
+       f = setmntent("/proc/mounts", "r");
+       if (!f) {
+               td_verror(td, errno, "setmntent /proc/mounts");
+               return NULL;
+       }
+
+       while ((mnt = getmntent(f)) != NULL) {
+               if (!strcmp(mnt->mnt_type, "cgroup") &&
+                   strstr(mnt->mnt_opts, "blkio"))
+                       break;
+       }
+
+       if (mnt)
+               mntpoint = smalloc_strdup(mnt->mnt_dir);
+       else
+               log_err("fio: cgroup blkio does not appear to be mounted\n");
+
+       endmntent(f);
+       return mntpoint;
+}
+
 static void add_cgroup(const char *name, struct flist_head *clist)
 {
        struct cgroup_member *cm;
@@ -46,26 +74,14 @@ void cgroup_kill(struct flist_head *clist)
        fio_mutex_up(lock);
 }
 
-/*
- * Check if the given root appears valid
- */
-static int cgroup_check_fs(struct thread_data *td)
-{
-       struct stat sb;
-       char tmp[256];
-
-       sprintf(tmp, "%s/tasks", td->o.cgroup_root);
-       return stat(tmp, &sb);
-}
-
-static char *get_cgroup_root(struct thread_data *td)
+static char *get_cgroup_root(struct thread_data *td, char *mnt)
 {
        char *str = malloc(64);
 
        if (td->o.cgroup)
-               sprintf(str, "%s/%s", td->o.cgroup_root, td->o.cgroup);
+               sprintf(str, "%s/%s", mnt, td->o.cgroup);
        else
-               sprintf(str, "%s/%s", td->o.cgroup_root, td->o.name);
+               sprintf(str, "%s/%s", mnt, td->o.name);
 
        return str;
 }
@@ -100,30 +116,31 @@ static int cgroup_write_pid(struct thread_data *td, const char *root)
 /*
  * Move pid to root class
  */
-static int cgroup_del_pid(struct thread_data *td)
+static int cgroup_del_pid(struct thread_data *td, char *mnt)
 {
-       return cgroup_write_pid(td, td->o.cgroup_root);
+       return cgroup_write_pid(td, mnt);
 }
 
-int cgroup_setup(struct thread_data *td, struct flist_head *clist)
+int cgroup_setup(struct thread_data *td, struct flist_head *clist, char **mnt)
 {
        char *root;
 
-       if (cgroup_check_fs(td)) {
-               log_err("fio: blkio cgroup mount point %s not valid\n",
-                                                       td->o.cgroup_root);
-               return 1;
+       if (!*mnt) {
+               *mnt = find_cgroup_mnt(td);
+               if (!*mnt)
+                       return 1;
        }
 
        /*
         * Create container, if it doesn't exist
         */
-       root = get_cgroup_root(td);
+       root = get_cgroup_root(td, *mnt);
        if (mkdir(root, 0755) < 0) {
                int __e = errno;
 
                if (__e != EEXIST) {
                        td_verror(td, __e, "cgroup mkdir");
+                       log_err("fio: path %s\n", root);
                        goto err;
                }
        } else
@@ -146,14 +163,14 @@ err:
        return 1;
 }
 
-void cgroup_shutdown(struct thread_data *td)
+void cgroup_shutdown(struct thread_data *td, char **mnt)
 {
-       if (cgroup_check_fs(td))
+       if (*mnt == NULL)
                return;
-       if (!td->o.cgroup_weight && td->o.cgroup)
+       if (!td->o.cgroup_weight && !td->o.cgroup)
                return;
 
-       cgroup_del_pid(td);
+       cgroup_del_pid(td, *mnt);
 }
 
 static void fio_init cgroup_init(void)