[libvirt] [PATCH 1/1] Add shrink flag to blockresize command
From: patchon <martinsson.patrik(a)gmail.com>
These commits simply adds the '--shrink' flag to the blockresize
command to prevent accidental shrinking of a block device. This
behaviour is already present on the vol-resize command and it
makes sense to mimic that behaviour.
Only implemented in the qemu-driver atm.
Signed-off-by: Patrik Martinsson <martinsson.patrik(a)gmail.com>
---
src/qemu/qemu_driver.c | 15 ++++++++++++++-
tools/virsh-domain.c | 7 +++++++
tools/virsh.pod | 9 ++++++++-
3 files changed, 29 insertions(+), 2 deletions(-)
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 95fe844c34..4e34eec796 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -11265,8 +11265,10 @@ qemuDomainBlockResize(virDomainPtr dom,
char *device = NULL;
const char *nodename = NULL;
virDomainDiskDefPtr disk = NULL;
+ virDomainBlockInfo info;
- virCheckFlags(VIR_DOMAIN_BLOCK_RESIZE_BYTES, -1);
+ virCheckFlags(VIR_DOMAIN_BLOCK_RESIZE_BYTES |
+ VIR_STORAGE_VOL_RESIZE_SHRINK, -1);
/* We prefer operating on bytes. */
if ((flags & VIR_DOMAIN_BLOCK_RESIZE_BYTES) == 0) {
@@ -11279,6 +11281,9 @@ qemuDomainBlockResize(virDomainPtr dom,
size *= 1024;
}
+ if (virDomainGetBlockInfo(dom, path, &info, 0) < 0)
+ goto cleanup;
+
if (!(vm = qemuDomainObjFromDomain(dom)))
goto cleanup;
@@ -11299,6 +11304,14 @@ qemuDomainBlockResize(virDomainPtr dom,
goto endjob;
}
+ if (size < info.capacity &&
+ !(flags & VIR_STORAGE_VOL_RESIZE_SHRINK)) {
+ virReportError(VIR_ERR_INVALID_ARG, "%s",
+ _("Can't shrink capacity below current "
+ "capacity unless shrink flag explicitly specified"));
+ goto endjob;
+ }
+
/* qcow2 and qed must be sized on 512 byte blocks/sectors,
* so adjust size if necessary to round up.
*/
diff --git a/tools/virsh-domain.c b/tools/virsh-domain.c
index fbfdc09c0d..a67ee35428 100644
--- a/tools/virsh-domain.c
+++ b/tools/virsh-domain.c
@@ -2920,6 +2920,10 @@ static const vshCmdOptDef opts_blockresize[] = {
.flags = VSH_OFLAG_REQ,
.help = N_("New size of the block device, as scaled integer (default
KiB)")
},
+ {.name = "shrink",
+ .type = VSH_OT_BOOL,
+ .help = N_("allow the resize to shrink the volume")
+ },
{.name = NULL}
};
@@ -2938,6 +2942,9 @@ cmdBlockresize(vshControl *ctl, const vshCmd *cmd)
if (vshCommandOptScaledInt(ctl, cmd, "size", &size, 1024, ULLONG_MAX)
< 0)
return false;
+ if (vshCommandOptBool(cmd, "shrink"))
+ flags |= VIR_STORAGE_VOL_RESIZE_SHRINK;
+
/* Prefer the older interface of KiB. */
if (size % 1024 == 0)
size /= 1024;
diff --git a/tools/virsh.pod b/tools/virsh.pod
index cf2798e71a..96387127d6 100644
--- a/tools/virsh.pod
+++ b/tools/virsh.pod
@@ -1027,7 +1027,7 @@ I<bandwidth> specifies copying bandwidth limit in MiB/s. For
further information
on the I<bandwidth> argument see the corresponding section for the
B<blockjob>
command.
-=item B<blockresize> I<domain> I<path> I<size>
+=item B<blockresize> I<domain> I<path> I<--size>
I<--shrink>
Resize a block device of domain while the domain is running, I<path>
specifies the absolute path of the block device; it corresponds
@@ -1040,6 +1040,13 @@ I<size> is a scaled integer (see B<NOTES> above) which
defaults to KiB
"B" to get bytes (note that for historical reasons, this differs from
B<vol-resize> which defaults to bytes without a suffix).
+Attempts to shrink the block device will fail unless I<--shrink> is present.
+The I<capacity> cannot be negative since the given capacity is the absolute
+size of the block device. Always exercise caution when shrinking a block device.
+B<Also note> that it is up to the driver to implement the check if shrinking
+should be allowed or not depending on if I<--shrink> is set. So far only the
+qemu-driver does this.
+
=item B<console> I<domain> [I<devname>] [I<--safe>]
[I<--force>]
Connect the virtual serial console for the guest. The optional
--
2.23.0