# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1257237561 0
# Node ID 830bda7a9c7565469abb5946c03ccad450197349
# Parent 2ddad83e9733b006afb1169fe8a1bc02cfa41848
Linux vbd hotplug: Speed up finding a loopback device
- Use the device and inode information provided by losetup to find
if the vbd backing file is in use on another vbd.
- Use losetup to find a free loopback device.
Signed-off-by: Gary Grebus <gary.grebus@xxxxxxxxxx>
---
tools/hotplug/Linux/block | 97 +++++++---------------------------------------
1 files changed, 15 insertions(+), 82 deletions(-)
diff -r 2ddad83e9733 -r 830bda7a9c75 tools/hotplug/Linux/block
--- a/tools/hotplug/Linux/block Tue Nov 03 08:38:55 2009 +0000
+++ b/tools/hotplug/Linux/block Tue Nov 03 08:39:21 2009 +0000
@@ -250,94 +250,27 @@ mount it read-write in a guest domain."
mount it read-write in a guest domain."
fi
- loopdev=''
- for dev in /dev/loop*
- do
- if [ ! -b "$dev" ]
+ if [ "x$mode" != 'x!' ]
+ then
+ inode=$(stat -c '%i' $file)
+ dev=$(stat -c '%D' $file)
+ if [ -z "$inode" ] || [ -z "$dev" ]
then
- continue
+ fatal "Unable to lookup $file: dev: $dev inode: $inode"
fi
- f=$(losetup "$dev" 2>/dev/null) || f=''
-
- if [ "$f" ]
- then
- # $dev is in use. Check sharing.
- if [ "x$mode" = 'x!' ]
- then
- continue
- fi
-
- f=$(echo "$f" | sed -e 's/.*(\(.*\)).*/\1/g')
-
- # $f is the filename, as read from losetup, but the loopback
- # driver truncates filenames at 64 characters, so we need to go
- # trawling through the store if it's longer than that. Truncation
- # is indicated by an asterisk at the end of the filename.
- if expr index "$f" '*' >/dev/null
- then
- found=""
- for dom in $(xenstore-list "$XENBUS_BASE_PATH")
- do
- for domdev in $(xenstore-list "$XENBUS_BASE_PATH/$dom")
- do
- d=$(xenstore_read_default \
- "$XENBUS_BASE_PATH/$dom/$domdev/node" "")
- if [ "$d" = "$dev" ]
- then
- f=$(xenstore_read "$XENBUS_BASE_PATH/$dom/$domdev/params")
- found=1
- break 2
- fi
- done
- done
-
- if [ ! "$found" ]
- then
- # This loopback device is in use by someone else, so skip it.
- log debug "Loopback sharing check skips device $dev."
- continue
- fi
- fi
-
- # Canonicalise the filename for the comparison.
-
- # I have seen this readlink fails because the filename given by
- # losetup is only the basename. This cannot happen when the loop
- # device is set up through this script, because file is
- # canonicalised above, but it may happen when loop devices are set
- # up some other way. This readlink may also conceivably fail if
- # the file backing this loop device has been removed.
-
- # For maximum safety, in the case that $f does not resolve, we
- # assume that $file and $f are in the same directory.
-
- # If you create a loopback filesystem, remove it and continue to
- # run on it, and then create another file with the same name, then
- # this check will block that -- don't do that.
-
- # If you create loop devices through some other mechanism, use
- # relative filenames, and then use the same filename through this
- # script, then this check will block that -- don't do that either.
-
- f=$(readlink -f "$f" || echo $(dirname "$file")/$(basename "$f"))
-
-
- if [ "$f" = "$file" ]
+ shared_list=$(losetup -a | grep ' \[0*'${dev}'\]:'${inode} |
+ cut -d : -f 1)
+ for dev in "$shared_list"
+ do
+ if [ -n "$dev" ]
then
check_file_sharing "$file" "$dev" "$mode"
fi
- else
- # $dev is not in use, so we'll remember it for use later; we want
- # to finish the sharing check first.
-
- if [ "$loopdev" = '' ]
- then
- loopdev="$dev"
- fi
- fi
- done
-
+ done
+ fi
+
+ loopdev=$(losetup -f)
if [ "$loopdev" = '' ]
then
release_lock "block"
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