utils: fs: error out if mkfs fails

If formatting fails, log shows:

	mkfs.ntfs reports return code 1 for /dev/sda2

but ogclient reports success to the ogserver.

Raise an exception so front-end gets an indication that formatting has failed.

src/live/ogOperations.py

@@ -429,9 +429,12 @@ class OgLiveOperations:
 
             partition = int(part["partition"])
             if fs == 'cache':
-                mkfs('ext4', int(disk), partition, label='CACHE')
+                err = mkfs('ext4', int(disk), partition, label='CACHE')
             else:
-                mkfs(fs, int(disk), partition)
+                err = mkfs(fs, int(disk), partition)
+
+            if err == -1:
+                raise OgError(f'Failed to format {part["partition"]} with filesystem {part["filesystem"]}')
 
         ret = subprocess.run(['partprobe', f'/dev/{diskname}'])
         logging.info(f'second partprobe /dev/{diskname} reports {ret.returncode}')

src/utils/fs.py

@@ -165,10 +165,11 @@ def mkfs(fs, disk, partition, label=None):
     except ValueError as e:
         raise OgError(f'mkfs aborted: {e}') from e
 
-    fsdict[fs](partdev, label)
+    return fsdict[fs](partdev, label)
 
 
 def mkfs_ext4(partdev, label=None):
+    err = -1
     if label:
         cmd = shlex.split(f'mkfs.ext4 -L {label} -F {partdev}')
     else:
@@ -177,12 +178,15 @@ def mkfs_ext4(partdev, label=None):
         ret = subprocess.run(cmd,
                              stdout=logfile,
                              stderr=STDOUT)
-
+        err = ret.returncode
         if ret.returncode != 0:
             logging.error(f'mkfs.ext4 reports return code {ret.returncode} for {partdev}')
 
+    return err
+
 
 def mkfs_ntfs(partdev, label=None):
+    err = -1
     if label:
         cmd = shlex.split(f'mkfs.ntfs -f -L {label} {partdev}')
     else:
@@ -191,12 +195,15 @@ def mkfs_ntfs(partdev, label=None):
         ret = subprocess.run(cmd,
                              stdout=logfile,
                              stderr=STDOUT)
-
+        err = ret.returncode
         if ret.returncode != 0:
             logging.error(f'mkfs.ntfs reports return code {ret.returncode} for {partdev}')
 
+    return err
+
 
 def mkfs_fat32(partdev, label=None):
+    err = -1
     if label:
         cmd = shlex.split(f'mkfs.vfat -n {label} -F32 {partdev}')
     else:
@@ -205,12 +212,15 @@ def mkfs_fat32(partdev, label=None):
         ret = subprocess.run(cmd,
                              stdout=logfile,
                              stderr=STDOUT)
-
+        err = ret.returncode
         if ret.returncode != 0:
             logging.error(f'mkfs.vfat reports return code {ret.returncode} for {partdev}')
 
+    return err
+
 
 def mkfs_swap(partdev, label=None):
+    err = -1
     if label:
         cmd = shlex.split(f'mkswap -f -L {label} {partdev}')
     else:
@@ -219,10 +229,12 @@ def mkfs_swap(partdev, label=None):
         ret = subprocess.run(cmd,
                              stdout=logfile,
                              stderr=STDOUT)
-
+        err = ret.returncode
         if ret.returncode != 0:
             logging.error(f'mkswap reports return code {ret.returncode} for {partdev}')
 
+    return err
+
 
 def get_filesystem_type(partdev):
     """