mirror of
https://git.yoctoproject.org/poky
synced 2026-04-24 03:32:13 +02:00
c4acf1b531
Copying files from the read-only root filesystem to the tmpfs providing the volatile directories can be slow and waste memory. If the kernel supports the overlay filesystem, use it to mount a writable tmpfs on top of the read-only directory from the rootfs and avoid copies. Analogous to the modification made to initscripts's read-only-rootfs-hook in 370fda1b2e8d5dc011522131bba4106de26bfb19. (From OE-Core rev: b4976f3cf8cd028f165100b67867adb862da4d7f) Signed-off-by: Matt Hoosier <matt.hoosier@gmail.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
1.3 KiB
Executable File
1.3 KiB
Executable File
#!/bin/sh
Perform a bind mount, copying existing files as we do so to ensure the
overlaid path has the necessary content.
if [ $# -lt 2 ]; then echo >&2 "Usage: $0 spec mountpoint [OPTIONS]" exit 1 fi
e.g. /var/volatile/lib
spec=$1
e.g. /var/lib
mountpoint=$2
if [ $# -gt 2 ]; then options=$3 else options= fi
[ -n "$options" ] && options=",$options"
mkdir -p "${spec%/*}"
if [ -d "$mountpoint" ]; then
if [ -d "$spec" ]; then
specdir_existed=yes
else
specdir_existed=no
mkdir "$spec"
fi
# Fast version of calculating `dirname ${spec}`/.`basename ${spec}`-work
overlay_workdir="${spec%/*}/.${spec##*/}-work"
mkdir "${overlay_workdir}"
# Try to mount using overlay, which is must faster than copying files.
# If that fails, fall back to slower copy.
if ! mount -t overlay overlay -olowerdir="$mountpoint",upperdir="$spec",workdir="$overlay_workdir" "$mountpoint" > /dev/null 2>&1; then
if [ "$specdir_existed" != "yes" ]; then
cp -pPR "$mountpoint"/. "$spec/"
fi
mount -o "bind$options" "$spec" "$mountpoint"
fi
elif [ -f "$mountpoint" ]; then if [ ! -f "$spec" ]; then cp -pP "$mountpoint" "$spec" fi
mount -o "bind$options" "$spec" "$mountpoint"
fi