[Xen-devel] tools/examples/block better use of losetup -r

[Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>]

The attached change arranges to use losetup -r when the vbd is
specified to be readonly, but only if -r is supported (rather than
always creating a writeable losetup mapping if possible).

This was inspired by (but not derived from) a diff from the Fedora 8
patchset which uses -r iff the vbd is specified as readonly.  We need
to be cleverer upstream because not all systems have losetup -r.

Ian.

Signed-off-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>

Index: xen-unstable.hg/tools/examples/block
===================================================================
--- xen-unstable.hg.orig/tools/examples/block   2007-12-19 10:54:05.000000000 
+0000
+++ xen-unstable.hg/tools/examples/block        2007-12-19 11:47:44.000000000 
+0000
@@ -327,10 +327,13 @@
           fatal 'Failed to find an unused loop device'
         fi
 
-        status=$(losetup "$loopdev" "$file" || echo "failed")
-        if [ -n "$status" ]; then
-          do_or_die losetup -r "$loopdev" "$file"
+        if LANG=C losetup -h 2>&1 | grep read-only >/dev/null
+        then
+          roflag="-$mode"; roflag="${roflag#-w}"
+        else
+          roflag=''
         fi
+        do_or_die losetup $roflag "$loopdev" "$file"
         xenstore_write "$XENBUS_PATH/node" "$loopdev"
         write_dev "$loopdev"
         release_lock "block"

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel