Merge pull request #1622 from Chrysostomus/btrfs-subvol

[fstab][mount] Create and mount btrfs subvolumes in generalized manner

src/modules/fstab/main.py

@@ -183,37 +183,19 @@ class FstabGenerator(object):
             print(FSTAB_HEADER, file=fstab_file)
 
             for partition in self.partitions:
-                # Special treatment for a btrfs root with @, @home and @swap
-                # subvolumes
+                # Special treatment for a btrfs subvolumes
                 if (partition["fs"] == "btrfs"
                    and partition["mountPoint"] == "/"):
-                    output = subprocess.check_output(['btrfs',
-                                                      'subvolume',
-                                                      'list',
-                                                      self.root_mount_point])
-                    output_lines = output.splitlines()
-                    for line in output_lines:
-                        if line.endswith(b'path @'):
-                            root_entry = partition
-                            root_entry["subvol"] = "@"
-                            dct = self.generate_fstab_line_info(root_entry)
-                            if dct:
+                    # Subvolume list has been created in mount.conf and curated in mount module,
+                    # so all subvolumes here should be safe to add to fstab
+                    btrfs_subvolumes = libcalamares.globalstorage.value("btrfsSubvolumes")
+                    for s in btrfs_subvolumes:
+                        mount_entry = partition
+                        mount_entry["mountPoint"] = s["mountPoint"]
+                        mount_entry["subvol"] = s["subvolume"]
+                        dct = self.generate_fstab_line_info(mount_entry)
+                        if dct:
                                 self.print_fstab_line(dct, file=fstab_file)
-                        elif line.endswith(b'path @home'):
-                            home_entry = partition
-                            home_entry["mountPoint"] = "/home"
-                            home_entry["subvol"] = "@home"
-                            dct = self.generate_fstab_line_info(home_entry)
-                            if dct:
-                                self.print_fstab_line(dct, file=fstab_file)
-                        elif line.endswith(b'path @swap'):
-                            swap_part_entry = partition
-                            swap_part_entry["mountPoint"] = "/swap"
-                            swap_part_entry["subvol"] = "@swap"
-                            dct = self.generate_fstab_line_info(swap_part_entry)
-                            if dct:
-                                self.print_fstab_line(dct, file=fstab_file)
-
                 else:
                     dct = self.generate_fstab_line_info(partition)
                     if dct:

src/modules/mount/main.py

@@ -32,9 +32,6 @@ def pretty_name():
 def mount_partition(root_mount_point, partition, partitions):
     """
     Do a single mount of @p partition inside @p root_mount_point.
-
-    The @p partitions are used to handle btrfs special-cases:
-    then subvolumes are created for root and home.
     """
     # Create mount point with `+` rather than `os.path.join()` because
     # `partition["mountPoint"]` starts with a '/'.
@@ -74,36 +71,29 @@ def mount_partition(root_mount_point, partition, partitions):
                                 partition.get("options", "")) != 0:
         libcalamares.utils.warning("Cannot mount {}".format(device))
 
-    # If the root partition is btrfs, we create a subvolume "@"
-    # for the root mount point.
-    # If a separate /home partition isn't defined, we also create
-    # a subvolume "@home".
-    # If a swapfile is used, we also create a subvolume "@swap".
-    # Finally we remount all of the above on the correct paths.
+    # Special handling for btrfs subvolumes. Create the subvolumes listed in mount.conf
     if fstype == "btrfs" and partition["mountPoint"] == '/':
-        has_home_mount_point = False
+        # Root has been mounted to btrfs volume -> create subvolumes from configuration
+        btrfs_subvolumes = libcalamares.job.configuration.get("btrfsSubvolumes") or []
+        subvolume_mountpoints = [d['mountPoint'] for d in btrfs_subvolumes]
+        # Check if listed mountpoints besides / are already present and don't create subvolume for those
         for p in partitions:
             if "mountPoint" not in p or not p["mountPoint"]:
                 continue
-            if p["mountPoint"] == "/home":
-                has_home_mount_point = True
-                break
-        needs_swap_subvolume = False
+            if p["mountPoint"] in subvolume_mountpoints and p["mountPoint"] != '/':
+                btrfs_subvolumes = [d for d in btrfs_subvolumes if d['mountPoint'] != p["mountPoint"]]
+        # Check if we need a subvolume for swap file
         swap_choice = global_storage.value( "partitionChoices" )
         if swap_choice:
             swap_choice = swap_choice.get( "swap", None )
             if swap_choice and swap_choice == "file":
-                needs_swap_subvolume = True
-
-        subprocess.check_call(['btrfs', 'subvolume', 'create',
-                               root_mount_point + '/@'])
-
-        if not has_home_mount_point:
+                btrfs_subvolumes.append({'mountPoint': '/swap', 'subvolume': '/@swap'})
+        # Store created list in global storage so it can be used in the fstab module
+        libcalamares.globalstorage.insert("btrfsSubvolumes", btrfs_subvolumes)
+        # Create the subvolumes that are in the completed list
+        for s in btrfs_subvolumes:
             subprocess.check_call(['btrfs', 'subvolume', 'create',
-                                   root_mount_point + '/@home'])
-        if needs_swap_subvolume:
-            subprocess.check_call(['btrfs', 'subvolume', 'create',
-                                       root_mount_point + '/@swap'])
+                               root_mount_point + s['subvolume']])
 
         subprocess.check_call(["umount", "-v", root_mount_point])
 
@@ -112,24 +102,14 @@ def mount_partition(root_mount_point, partition, partitions):
         if "luksMapperName" in partition:
             device = os.path.join("/dev/mapper", partition["luksMapperName"])
 
-        if libcalamares.utils.mount(device,
-                                    mount_point,
-                                    fstype,
-                                    ",".join(["subvol=@", partition.get("options", "")])) != 0:
-            libcalamares.utils.warning("Cannot mount {}".format(device))
-
-        if not has_home_mount_point:
-            if libcalamares.utils.mount(device,
-                                        root_mount_point + "/home",
-                                        fstype,
-                                        ",".join(["subvol=@home", partition.get("options", "")])) != 0:
-                libcalamares.utils.warning("Cannot mount {}".format(device))
-        
-        if needs_swap_subvolume:
+        # Mount the subvolumes
+        for s in btrfs_subvolumes:
+            mount_option = "subvol={}".format(s['subvolume'])
+            subvolume_mountpoint = mount_point[:-1] + s['mountPoint']
             if libcalamares.utils.mount(device,
-                                        root_mount_point + "/swap",
-                                        fstype,
-                                        ",".join(["subvol=@swap", partition.get("options", "")])) != 0:
+                                    subvolume_mountpoint,
+                                    fstype,
+                                    ",".join([mount_option, partition.get("options", "")])) != 0:
                 libcalamares.utils.warning("Cannot mount {}".format(device))
 
 

src/modules/mount/mount.conf

@@ -40,3 +40,17 @@ extraMountsEfi:
     - device: efivarfs
       fs: efivarfs
       mountPoint: /sys/firmware/efi/efivars
+
+# Btrfs subvolumes to create if root filesystem is on btrfs volume.
+# If mountpoint is mounted already to another partition, it is ignored.
+# Separate subvolume for swapfile is handled separately and automatically.
+
+btrfsSubvolumes:
+    - mountPoint: /
+      subvolume: /@
+    - mountPoint: /home
+      subvolume: /@home
+    - mountPoint: /var/cache
+      subvolume: /@cache
+    - mountPoint: /var/log
+      subvolume: /@log

src/modules/mount/mount.schema.yaml

@@ -29,3 +29,12 @@ properties:
                 mountPoint: { type: string }
                 options: { type: string }
             required: [ device, mountPoint ]
+    btrfsSubvolumes:
+        type: array
+        items:
+            type: object
+            additionalProperties: false
+            properties:
+                mountPoint: { type: string }
+                subvolume: { type: string }
+            required: [ subvolume, mountPoint ]