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https://github.com/xen-project/xen.git
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Keir Fraser
b6cd10140c
currently the function same_vm in block-common.sh is the one responsible for detecting if two block devices can be used at the same time by two VMs. This can be allowed in few specific cases: when the two VMs are actually the same VM and when the two VMs are the guest and its stubdomain. We need to expand these exceptions to handle properly save restore issues: this patch adds to the exceptions the case when two VMs are the same VM because of save\restore races, and when two VMs are the guest and the stubdomain of the previous guest, again during save\restore. Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
126 lines
3.1 KiB
Bash
126 lines
3.1 KiB
Bash
#
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# Copyright (c) 2005 XenSource Ltd.
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#
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# This library is free software; you can redistribute it and/or
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# modify it under the terms of version 2.1 of the GNU Lesser General Public
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# License as published by the Free Software Foundation.
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#
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# This library is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# Lesser General Public License for more details.
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#
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# You should have received a copy of the GNU Lesser General Public
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# License along with this library; if not, write to the Free Software
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# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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#
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dir=$(dirname "$0")
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. "$dir/xen-hotplug-common.sh"
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findCommand "$@"
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if [ "$command" != "add" ] &&
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[ "$command" != "remove" ]
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then
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log err "Invalid command: $command"
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exit 1
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fi
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XENBUS_PATH="${XENBUS_PATH:?}"
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ebusy()
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{
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xenstore_write "$XENBUS_PATH/hotplug-error" "$*" \
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"$XENBUS_PATH/hotplug-status" busy
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log err "$@"
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exit 1
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}
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##
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# Print the given device's major and minor numbers, written in hex and
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# separated by a colon.
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device_major_minor()
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{
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stat -L -c %t:%T "$1"
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}
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##
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# Write physical-device = MM,mm to the store, where MM and mm are the major
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# and minor numbers of device respectively.
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#
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# @param device The device from which major and minor numbers are read, which
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# will be written into the store.
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#
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write_dev() {
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local mm
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mm=$(device_major_minor "$1")
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if [ -z $mm ]
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then
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fatal "Backend device does not exist"
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fi
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xenstore_write "$XENBUS_PATH/physical-device" "$mm"
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success
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}
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##
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# canonicalise_mode mode
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#
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# Takes the given mode, which may be r, w, ro, rw, w!, or rw!, or variations
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# thereof, and canonicalises them to one of
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#
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# 'r': perform checks for a new read-only mount;
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# 'w': perform checks for a read-write mount; or
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# '!': perform no checks at all.
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#
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canonicalise_mode()
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{
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local mode="$1"
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if ! expr index "$mode" 'w' >/dev/null
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then
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echo 'r'
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elif ! expr index "$mode" '!' >/dev/null
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then
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echo 'w'
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else
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echo '!'
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fi
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}
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same_vm()
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{
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local otherdom="$1"
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# Note that othervm can be MISSING here, because Xend will be racing with
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# the hotplug scripts -- the entries in /local/domain can be removed by
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# Xend before the hotplug scripts have removed the entry in
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# /local/domain/0/backend/. In this case, we want to pretend that the
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# VM is the same as FRONTEND_UUID, because that way the 'sharing' will be
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# allowed.
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local othervm=$(xenstore_read_default "/local/domain/$otherdom/vm" \
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"$FRONTEND_UUID")
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local target=$(xenstore_read_default "/local/domain/$FRONTEND_ID/target" \
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"-1")
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local otarget=$(xenstore_read_default "/local/domain/$otherdom/target" \
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"-1")
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local otvm=$(xenstore_read_default "/local/domain/$otarget/vm" \
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"-1")
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otvm=${otvm%-1}
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othervm=${othervm%-1}
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local frontend_uuid=${FRONTEND_UUID%-1}
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[ "$frontend_uuid" = "$othervm" -o "$target" = "$otherdom" -o "$frontend_uuid" = "$otvm" ]
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}
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