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a04255b4eb
I *think* there is a new check that wasn't previously (in 19.03) part of e2fsck. This is now causing the check to fail. FIXME : figure out a way to disable the check, or make the image comply.
114 lines
3.7 KiB
Nix
114 lines
3.7 KiB
Nix
{ lib, imageBuilder, libfaketime, e2fsprogs, make_ext4fs }:
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/* */ let scope = { "fileSystem.makeExt4" =
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let
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inherit (lib.strings) splitString;
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inherit (imageBuilder) makeFilesystem;
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# Bash doesn't do floating point representations. Multiplications and divisions
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# are handled with enough precision that we can multiply and divide to get a precision.
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precision = 1000;
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first = list: lib.lists.last (lib.lists.reverseList list);
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chopDecimal = f: first (splitString "." (toString f));
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makeFudge = f: toString (chopDecimal (f * precision));
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# This applies only to 256MiB and greater.
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# For smaller than 256MiB images the overhead from the FS is much greater.
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# This will also let *some* slack space at the end at greater sizes.
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# This is the value at 512MiB where it goes slightly down compared to 256MiB.
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fudgeFactor = makeFudge 0.05208587646484375;
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# This table was built using a script that built an image with `make_ext4fs`
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# for the given size in MiB, and recorded the available size according to `df`.
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smallFudgeLookup = lib.strings.concatStringsSep "\n" (lib.lists.reverseList(
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lib.attrsets.mapAttrsToList (size: factor: ''
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elif (( size > ${toString size} )); then
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fudgeFactor=${toString factor}
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'') {
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"${toString (imageBuilder.size.MiB 5)}" = makeFudge 0.84609375;
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"${toString (imageBuilder.size.MiB 8)}" = makeFudge 0.5419921875;
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"${toString (imageBuilder.size.MiB 16)}" = makeFudge 0.288818359375;
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"${toString (imageBuilder.size.MiB 32)}" = makeFudge 0.1622314453125;
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"${toString (imageBuilder.size.MiB 64)}" = makeFudge 0.09893798828125;
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"${toString (imageBuilder.size.MiB 128)}" = makeFudge 0.067291259765625;
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"${toString (imageBuilder.size.MiB 256)}" = makeFudge 0.0518646240234375;
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}
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));
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minimumSize = imageBuilder.size.MiB 5;
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in
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{ partitionID
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, blockSize ? imageBuilder.size.KiB 4
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, ... } @ args:
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makeFilesystem (args // {
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filesystemType = "ext4";
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inherit blockSize minimumSize;
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nativeBuildInputs = [
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e2fsprogs
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make_ext4fs
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libfaketime
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];
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filesystemPhase = ''
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:
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'';
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computeMinimalSize = ''
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# `local size` is in bytes.
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# We don't have a static reserved factor figured out. It is rather hard with
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# ext4fs as there are multiple factors increasing the overhead.
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local reservedSize=0
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local fudgeFactor=${toString fudgeFactor}
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# Instead we rely on a lookup table. See how it is built in the derivation file.
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if (( size < ${toString (imageBuilder.size.MiB 256)} )); then
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echo "$size is smaller than 256MiB; using the lookup table." 1>&2
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# A bit of a hack, though allows us to build the lookup table using only
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# elifs.
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if false; then
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:
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${smallFudgeLookup}
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else
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# The data is smaller than 5MiB... The filesystem image size will likely
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# not be able to accomodate... here we handle it in another way.
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fudgeFactor=0
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echo "Fudge factor skipped for extra small partition. Instead increasing by a fixed amount." 1>&2
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size=$(( size + ${toString minimumSize}))
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fi
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fi
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local reservedSize=$(( size * $fudgeFactor / ${toString precision} ))
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echo "Fudge factor: $fudgeFactor / ${toString precision}" 1>&2
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echo -n "Adding reservedSize: $size + $reservedSize = " 1>&2
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size=$((size + reservedSize))
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echo "$size" 1>&2
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'';
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copyPhase = ''
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faketime -f "1970-01-01 00:00:00" \
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make_ext4fs \
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-b $blockSize \
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-L $partName \
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-l $size \
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-U $partitionID \
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"$img" \
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.
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'';
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checkPhase = ''
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'';
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# FIXME:
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# Padding at end of inode bitmap is not set. Fix? no
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# exit code
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#EXT2FS_NO_MTAB_OK=yes fsck.ext4 -n -f $img
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})
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/* */ ;}; in scope."fileSystem.makeExt4"
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