Merge pull request #964 from giuseppe/fallback-to-io.weight

cgroup: add fallback to io.weight

crun.1

@@ -879,6 +879,12 @@ l l l l .
 \fB\fCOCI (x)\fR	\fB\fCcgroup 2 value (y)\fR	\fB\fCconversion\fR	\fB\fCcomment\fR
 weight	io.bfq.weight	y = x	
 weight_device	io.bfq.weight	y = x	
+weight	io.weight (fallback)	y = 1 + (x-10)*9999/990	T{
+convert linearly from [10-1000] to [1-10000]
+T}
+weight_device	io.weight (fallback)	y = 1 + (x-10)*9999/990	T{
+convert linearly from [10-1000] to [1-10000]
+T}
 rbps	io.max	y=x	
 wbps	io.max	y=x	
 riops	io.max	y=x	

crun.1.md

@@ -676,6 +676,8 @@ they are converted when needed from the cgroup v1 configuration.
 |---|---|---|---|
 | weight | io.bfq.weight | y = x ||
 | weight_device | io.bfq.weight | y = x ||
+| weight | io.weight (fallback) | y = 1 + (x-10)*9999/990 | convert linearly from [10-1000] to [1-10000] |
+| weight_device | io.weight (fallback) | y = 1 + (x-10)*9999/990 | convert linearly from [10-1000] to [1-10000] |
 | rbps | io.max | y=x ||
 | wbps | io.max | y=x ||
 | riops | io.max |y=x ||

src/libcrun/cgroup-resources.c

@@ -212,9 +212,33 @@ write_blkio_resources (int dirfd, bool cgroup2, runtime_spec_schema_config_linux
       uint32_t val = blkio->weight;
 
       len = sprintf (fmt_buf, "%" PRIu32, val);
-      ret = write_cgroup_file (dirfd, cgroup2 ? "io.bfq.weight" : "blkio.weight", fmt_buf, len, err);
-      if (UNLIKELY (ret < 0))
-        return ret;
+      if (! cgroup2)
+        {
+          ret = write_cgroup_file (dirfd, "blkio.weight", fmt_buf, len, err);
+          if (UNLIKELY (ret < 0))
+            return ret;
+        }
+      else
+        {
+          ret = write_cgroup_file (dirfd, "io.bfq.weight", fmt_buf, len, err);
+          if (UNLIKELY (ret < 0))
+            {
+              if (crun_error_get_errno (err) == ENOENT)
+                {
+                  crun_error_release (err);
+
+                  /* convert linearly from [10-1000] to [1-10000] */
+                  val = 1 + (val - 10) * 9999 / 990;
+
+                  len = sprintf (fmt_buf, "%" PRIu32, val);
+
+                  ret = write_cgroup_file (dirfd, "io.weight", fmt_buf, len, err);
+                }
+
+              if (UNLIKELY (ret < 0))
+                return ret;
+            }
+        }
     }
   if (blkio->leaf_weight)
     {