[mount] Add additional documentation in mount.conf and main.py

src/modules/mount/main.py

@@ -58,22 +58,21 @@ def disk_name_for_partition(partition):
 
 
 def is_ssd_disk(partition):
-    """ Checks if given disk is actually a ssd disk.
+    """ Checks if given partition is on an ssd disk.
 
-    :param partition:
+    :param partition: A dict containing the partition information
-    :return:
+    :return: True is the partition in on an ssd, False otherwise
     """
 
-    disk_name = disk_name_for_partition(partition)
+    try:
-    filename = os.path.join("/sys/block", disk_name, "queue/rotational")
+        disk_name = disk_name_for_partition(partition)
+        filename = os.path.join("/sys/block", disk_name, "queue/rotational")
 
-    if not os.path.exists(filename):
+        with open(filename) as sysfile:
-        # Should not happen unless sysfs changes, but better safe than sorry
+            return sysfile.read() == "0\n"
+    except:
         return False
 
-    with open(filename) as sysfile:
-        return sysfile.read() == "0\n"
-
 
 def get_mount_options(filesystem, mount_options, partition):
     """

src/modules/mount/mount.conf

@@ -5,16 +5,15 @@
 # target as a usable chroot / "live" system). Filesystems are
 # automatically mounted from the partitioning module. Filesystems
 # listed here are **extra**. The filesystems listed in *extraMounts*
-# are mounted in all target systems. The filesystems listed in
+# are mounted in all target systems.
-# *extraMountsEfi* are mounted in the target system **only** if
-# the host machine uses UEFI.
 ---
 # Extra filesystems to mount. The key's value is a list of entries; each
-# entry has four keys:
+# entry has five keys:
 #   - device    The device node to mount
 #   - fs (optional) The filesystem type to use
 #   - mountPoint Where to mount the filesystem
-#   - options (optional) Extra options to pass to mount(8)
+#   - options (optional) An array of options to pass to mount
+#   - efi (optional) A boolean that when true is only mounted for UEFI installs
 #
 # The device is not mounted if the mountPoint is unset or if the fs is
 # set to unformatted.
@@ -47,7 +46,7 @@ extraMounts:
 # It is possible to prevent subvolume creation -- this is likely only relevant
 # for the root (/) subvolume -- by giving an empty string as a subvolume
 # name. In this case no subvolume will be created.
-
+#
 btrfsSubvolumes:
     - mountPoint: /
       subvolume: /@
@@ -61,17 +60,63 @@ btrfsSubvolumes:
     - mountPoint: /var/log
       subvolume: /@log
 
+# The name of the btrfs subvolume holding the swapfile.  This only used when
+# a swapfile is selected and the root filesystem is btrfs
+#
 btrfsSwapSubvol: /@swap
 
+# The mount options used to mount each filesystem.
+#
+# filsystem contains the name of the filesystem or on of three special
+# values, "default", efi" and "btrfs_swap".  The logic is applied in this manner:
+#   - If the partition is the EFI partition, the "efi" entry will be used
+#   - If the fs is btrfs and the subvolume is for the swapfile,
+#     the "btrfs_swap" entry is used
+#   - If the  filesystem is an exact match for filesystem, that entry is used
+#   - If no match is found in the above, the default entry is used
+#   - If there is no match and no default entry, "defaults" is used
+#   - If the mountOptions key is not present, "defaults" is used
+#
+# Each filesystem entry contains 3 keys, all of which are optional
+#   options - An array of mount options that is used on all disk types
+#   ssdOptions - An array of mount options combined with options for ssds
+#   hddOptions - An array of mount options combined with options for hdds
+# If combining these options results in an empty array, "defaults" is used
+#
+# Example 1
+# In this example, there are specific options for ext4 and btrfs filesystems,
+# the EFI partition and the subvolume holding the btrfs swapfile.  All other
+# filesystems use the default entry.  For the btrfs filesystem, there are
+# additional options specific to hdds and ssds
+#
+# mountOptions:
+#    - filesystem: default
+#      options: [ defaults ]
+#    - filesystem: efi
+#      options: [ defaults, umask=0077 ]
+#    - filesystem: ext4
+#      options: [ defaults, noatime ]
+#    - filesystem: btrfs
+#      options: [ defaults, noatime, compress=zstd:1 ]
+#      ssdOptions: [ discard=async ]
+#      hddOptions: [ autodefrag ]
+#    - filesystem: btrfs_swap
+#      options: [ defaults, noatime ]
+#
+# Example 2
+# In this example there is a single default used by all filesystems
+#
+# mountOptions:
+#    - filesystem: default
+#      options: [ defaults, noatime ]
+#
 mountOptions:
     - filesystem: default
       options: [ defaults, noatime ]
     - filesystem: efi
       options: [ defaults, umask=0077 ]
     - filesystem: btrfs
-      options: [ defaults, noatime, compress ]
+      options: [ defaults, noatime, compress=lzo ]
-      ssdOptions: [ discard=async ]
-      hddOptions: [ autodefrag ]
     - filesystem: btrfs_swap
       options: [ defaults, noatime ]