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2848e37111
Copying files from the read-only /var/lib to tmpfs can be slow and waste memory. If the kernel supports the overlay file system, use it to mount a writable tmpfs on top of the read-only /var/lib and avoid the file copy. (From OE-Core rev: 370fda1b2e8d5dc011522131bba4106de26bfb19) Signed-off-by: Joshua Watt <JPEWhacker@gmail.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
44 lines
1.2 KiB
Bash
44 lines
1.2 KiB
Bash
#!/bin/sh
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. /etc/default/rcS
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[ "$ROOTFS_READ_ONLY" = "no" ] && exit 0
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is_on_read_only_partition () {
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DIRECTORY=$1
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dir=`readlink -f $DIRECTORY`
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while true; do
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if [ ! -d "$dir" ]; then
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echo "ERROR: $dir is not a directory"
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exit 1
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else
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for flag in `awk -v dir=$dir '{ if ($2 == dir) { print "FOUND"; split($4,FLAGS,",") } }; \
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END { for (f in FLAGS) print FLAGS[f] }' < /proc/mounts`; do
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[ "$flag" = "FOUND" ] && partition="read-write"
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[ "$flag" = "ro" ] && { partition="read-only"; break; }
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done
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if [ "$dir" = "/" -o -n "$partition" ]; then
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break
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else
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dir=`dirname $dir`
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fi
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fi
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done
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[ "$partition" = "read-only" ] && echo "yes" || echo "no"
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}
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if [ "$1" = "start" ] ; then
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if [ `is_on_read_only_partition /var/lib` = "yes" ]; then
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grep -q "tmpfs /var/volatile" /proc/mounts || mount /var/volatile
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mkdir -p /var/volatile/lib
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mkdir -p /var/volatile/.lib-work
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# Try to mount using overlay, which is much faster than copying
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# files. If that fails, fallback to the slower copy
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if ! mount -t overlay overlay -olowerdir=/var/lib,upperdir=/var/volatile/lib,workdir=/var/volatile/.lib-work /var/lib > /dev/null 2>&1; then
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cp -a /var/lib/* /var/volatile/lib
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mount --bind /var/volatile/lib /var/lib
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fi
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fi
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fi
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