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authorMatt Hoosier <matt.hoosier@garmin.com>2018-10-19 11:04:55 -0500
committerRichard Purdie <richard.purdie@linuxfoundation.org>2018-10-20 22:39:25 +0100
commitb4976f3cf8cd028f165100b67867adb862da4d7f (patch)
treec4fe871d51c1664a597ee17b0e145f5a140cfb9a
parente028b4457781f60d8491a99a23011996fa913013 (diff)
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volatile-binds: use overlayfs if available
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. Signed-off-by: Matt Hoosier <matt.hoosier@gmail.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
-rwxr-xr-xmeta/recipes-core/volatile-binds/files/mount-copybind30
1 files changed, 26 insertions, 4 deletions
diff --git a/meta/recipes-core/volatile-binds/files/mount-copybind b/meta/recipes-core/volatile-binds/files/mount-copybind
index 2aeaf84ddb..fddf520053 100755
--- a/meta/recipes-core/volatile-binds/files/mount-copybind
+++ b/meta/recipes-core/volatile-binds/files/mount-copybind
@@ -8,7 +8,10 @@ if [ $# -lt 2 ]; then
exit 1
fi
+# e.g. /var/volatile/lib
spec=$1
+
+# e.g. /var/lib
mountpoint=$2
if [ $# -gt 2 ]; then
@@ -20,15 +23,34 @@ fi
[ -n "$options" ] && options=",$options"
mkdir -p "${spec%/*}"
+
if [ -d "$mountpoint" ]; then
- if [ ! -d "$spec" ]; then
+
+ if [ -d "$spec" ]; then
+ specdir_existed=yes
+ else
+ specdir_existed=no
mkdir "$spec"
- cp -pPR "$mountpoint"/. "$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
-fi
-mount -o "bind$options" "$spec" "$mountpoint"
+ mount -o "bind$options" "$spec" "$mountpoint"
+fi