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Describe the bug rd.writable.fsimg=1 causes the live image to be unpacked and copied into RAM. This used to work on F40 with a small modification of remounting /run to a larger size. That problem is described here https://github.com/dracutdevs/dracut/issues/2550

On F41 this workaround no longer works. After remounting /run to the larger size, boot fails with: mount: /run/rootfsbase: fsconfig system call failed: /dev/loop1: Can't open blockdev The problem happens on this line of dracut/modules.d/90dmsquash-live/dmsquash-live-root.sh: mount -r $FSIMG /run/rootfsbase mount -r /run/initramfs/fsimg/rootfs.img /run/rootfsbase

Can someone please point me to how to debug this further? I would like to find a workaround or a fix. Thanks. I can not find any reason why mount can not open the blockdev. Doing exactly the same on F40 works fine. All logs I tried do not have any further information.

Below is a modification of a dracut script that works on F40 and fails as above on F41: dracut/modules.d/90dmsquash-live/dmsquash-live-root.sh From line 368 to the end of the file.

if [ -n "$FSIMG" ]; then
    if [ -n "$writable_fsimg" ]; then
        # mount the provided filesystem read/write
        echo "############## HERE 1 ########################" > /dev/kmsg
        losetup > /dev/kmsg
        mount -t tmpfs -o remount,mode=755,rw,nosuid,nodev,size="16500M",nr_inodes=819200,inode64 tmpfs /run
        echo "TEST Unpacking live filesystem (may take some time)" > /dev/kmsg
        mkdir -m 0755 -p /run/initramfs/fsimg/
        if [ -n "$SQUASHED" ]; then
            cp -v $FSIMG /run/initramfs/fsimg/rootfs.img
        else
            echo "############## HERE 2 ########################" > /dev/kmsg
            unpack_archive $FSIMG /run/initramfs/fsimg/
        fi
        FSIMG=/run/initramfs/fsimg/rootfs.img
    fi
    # For writable DM images...
    readonly_base=1
    if [ -z "$SQUASHED" -a -n "$live_ram" -a -z "$overlayfs" ] \
        || [ -n "$writable_fsimg" ] \
        || [ "$overlay" = none -o "$overlay" = None -o "$overlay" = NONE ]; then
        if [ -z "$readonly_overlay" ]; then
            unset readonly_base
            setup=rw
        else
            setup=yes
        fi
    fi
    if [ "$FSIMG" = "$SQUASHED" ]; then
        BASE_LOOPDEV=$SQUASHED_LOOPDEV
    else
        echo "############## HERE 3 ########################" > /dev/kmsg
        BASE_LOOPDEV=$(losetup -f --show ${readonly_base:+-r} $FSIMG)
        echo "$BASE_LOOPDEV" > /dev/kmsg

        sz=$(blockdev --getsz "$BASE_LOOPDEV")
    fi
    if [ "$setup" = rw ]; then
        echo "############## HERE 4 ########################" > /dev/kmsg
        echo 0 "$sz" linear "$BASE_LOOPDEV" 0 | dmsetup create live-rw
    else
        # Add a DM snapshot or OverlayFS for writes.
        do_live_overlay
    fi
fi

if [ -n "$reloadsysrootmountunit" ]; then
    eval "$reloadsysrootmountunit"
    systemctl daemon-reload
fi

ROOTFLAGS="$(getarg rootflags)"

if [ "$overlayfs" = required ]; then
    echo "rd.live.overlay.overlayfs=1" > /etc/cmdline.d/dmsquash-need-overlay.conf
fi

if [ -n "$overlayfs" ]; then
    if [ -n "$FSIMG" ]; then
        mkdir -m 0755 -p /run/rootfsbase
        echo "#/run/initramfs/fsimg/... HERE 5 ###################" > /dev/kmsg
        echo "FSIMG var: mount -r $FSIMG /run/rootfsbase" > /dev/kmsg
        echo "############## HERE 5 ###################" > /dev/kmsg
        mount -r $FSIMG /run/rootfsbase
    else
        ln -sf /run/initramfs/live /run/rootfsbase
    fi
else
    if [ -z "$DRACUT_SYSTEMD" ]; then
        [ -n "$ROOTFLAGS" ] && ROOTFLAGS="-o $ROOTFLAGS"
        printf 'mount %s /dev/mapper/live-rw %s\n' "$ROOTFLAGS" "$NEWROOT" > "$hookdir"/mount/01-$$-live.sh
    fi
fi
[ -e "$SQUASHED" ] && umount -l /run/initramfs/squashfs

ln -s null /dev/root

need_shutdown

exit 0

Distribution used Fedora 41

Dracut version dracut-103-3.fc41.x86_64

Init system systemd

To Reproduce Use a computer with enough RAM and use the rd.writable.fsimg=1 boot parameter in grub config. Even in a VM with less RAM, the fail still happens, the test machine does not need 32 GB of RAM.

Expected behavior Same as F40, mount not failing, image is copied and boot continues as usual.