QubesOS/qubes-linux-utils
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Speed up udev-block-add-change by not using xenstore

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xenstore-ls is incredibly slow, while reading sysfs is much faster
This commit is contained in:
qubesuser 2017-11-08 03:09:54 +01:00
parent 19cb61a0ed
commit 4d08ff40a9
1 changed files with 9 additions and 10 deletions
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19
udev/udev-block-add-change Executable file → Normal file
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@ -49,21 +49,20 @@ refresh_another() {
env -i PATH=$PATH $launch_env $0 env -i PATH=$PATH $launch_env $0
} }
# communicate with xenstored through socket in dom0
# trying to access xenstore before xenstored is started, hang forever (in
# non-killable state), so better fail ('-s' in VM if /proc/xen isn't mounted
# yet) than hang dom0 boot
if [ ! -r /proc/xen/capabilities ] || grep -q control_d /proc/xen/capabilities; then
XENSTORE_LS="xenstore-ls -s"
else
XENSTORE_LS="xenstore-ls"
fi
is_attached() { is_attached() {
dev_hex=$(stat -c %t:%T /dev/$(basename $1)) dev_hex=$(stat -c %t:%T /dev/$(basename $1))
if [ -z "$dev_hex" -o "$dev_hex" = "0:0" ]; then if [ -z "$dev_hex" -o "$dev_hex" = "0:0" ]; then
return 1 return 1
fi fi
$XENSTORE_LS backend/vbd | grep -q "physical-device = \"$dev_hex\"" # looking at sysfs is much faster than looking at xenstore
# this code requires no subprocesses and doesn't hit argument length limitations
for i in /sys/bus/xen-backend/drivers/vbd/vbd-*/physical_device; do
read i_dev_hex < "$i"
if test "$i_dev_hex" == "$dev_hex"; then
return 0
fi
done
return 1
} }
# update info about parent devices, if any: # update info about parent devices, if any: