[lvm-devel] Allowing an actively merging snapshot to be removed?
Mike Snitzer
snitzer at redhat.com
Fri Apr 23 14:48:08 UTC 2010
On Thu, Apr 22 2010 at 7:36pm -0400,
Alasdair G Kergon <agk at redhat.com> wrote:
> On Wed, Apr 21, 2010 at 08:01:32PM -0400, Mikulas Patocka wrote:
> > I think the merging snapshot LV shouldn't be accessible
>
> Ack. We are past the user-generated 'commit' point at which it goes.
The following patch is one way to address this bug. Given the current
merge support in lvm2 this is the most straight-forward fix. I've
tested this to work well. Does the following seem reasonable?
Disallow the direct removal of a merging snapshot.
Allow lv_remove_with_dependencies() to know the top-level LV that was
requested to be removed (before it recurses and loses context).
A merging snapshot cannot be removed directly but the associated origin
can be. Disallow removal of a merging snapshot unless the associated
origin is also being removed.
Signed-off-by: Mike Snitzer <snitzer at redhat.com>
---
lib/metadata/lv_manip.c | 17 +++++++++++++----
lib/metadata/metadata-exported.h | 2 +-
lib/metadata/metadata.c | 2 +-
test/t-snapshot-merge.sh | 12 +++++++++---
tools/lvremove.c | 2 +-
5 files changed, 25 insertions(+), 10 deletions(-)
Index: lvm2/lib/metadata/lv_manip.c
===================================================================
--- lvm2.orig/lib/metadata/lv_manip.c
+++ lvm2/lib/metadata/lv_manip.c
@@ -2306,16 +2306,25 @@ int lv_remove_single(struct cmd_context
* remove LVs with its dependencies - LV leaf nodes should be removed first
*/
int lv_remove_with_dependencies(struct cmd_context *cmd, struct logical_volume *lv,
- const force_t force)
+ const force_t force, unsigned level)
{
struct dm_list *snh, *snht;
- if (lv_is_origin(lv)) {
+ if (lv_is_cow(lv)) {
+ /* A merging snapshot cannot be removed directly */
+ if (lv_is_merging_cow(lv) && !level) {
+ log_error("Can't remove merging snapshot logical volume \"%s\"",
+ lv->name);
+ return 0;
+ }
+ }
+
+ if (lv_is_origin(lv)) {
/* remove snapshot LVs first */
dm_list_iterate_safe(snh, snht, &lv->snapshot_segs) {
if (!lv_remove_with_dependencies(cmd, dm_list_struct_base(snh, struct lv_segment,
- origin_list)->cow,
- force))
+ origin_list)->cow,
+ force, level + 1))
return 0;
}
}
Index: lvm2/test/t-snapshot-merge.sh
===================================================================
--- lvm2.orig/test/t-snapshot-merge.sh
+++ lvm2/test/t-snapshot-merge.sh
@@ -44,17 +44,22 @@ setup_merge() {
aux prepare_vg 1 100
-# full merge of a single LV
+# test full merge of a single LV
setup_merge $vg $lv1
-
# now that snapshot LV is created: test if snapshot-merge target is available
$(dmsetup targets | grep -q snapshot-merge) || exit 200
-
lvs -a
lvconvert --merge $vg/$(snap_lv_name_ $lv1)
lvremove -f $vg/$lv1
+# test that an actively merging snapshot may not be removed
+setup_merge $vg $lv1
+lvconvert -i+100 --merge --background $vg/$(snap_lv_name_ $lv1)
+not lvremove -f $vg/$(snap_lv_name_ $lv1)
+lvremove -f $vg/$lv1
+
+
# "onactivate merge" test
setup_merge $vg $lv1
lvs -a
@@ -99,6 +104,7 @@ lvs -a
lvconvert --merge $vg/$(snap_lv_name_ $lv1)
lvremove -f $vg/$lv1
+
# test merging multiple snapshots that share the same tag
setup_merge $vg $lv1
setup_merge $vg $lv2
Index: lvm2/lib/metadata/metadata-exported.h
===================================================================
--- lvm2.orig/lib/metadata/metadata-exported.h
+++ lvm2/lib/metadata/metadata-exported.h
@@ -534,7 +534,7 @@ int lv_remove_single(struct cmd_context
force_t force);
int lv_remove_with_dependencies(struct cmd_context *cmd, struct logical_volume *lv,
- force_t force);
+ force_t force, unsigned level);
int lv_rename(struct cmd_context *cmd, struct logical_volume *lv,
const char *new_name);
Index: lvm2/lib/metadata/metadata.c
===================================================================
--- lvm2.orig/lib/metadata/metadata.c
+++ lvm2/lib/metadata/metadata.c
@@ -484,7 +484,7 @@ int remove_lvs_in_vg(struct cmd_context
while ((lst = dm_list_first(&vg->lvs))) {
lvl = dm_list_item(lst, struct lv_list);
- if (!lv_remove_with_dependencies(cmd, lvl->lv, force))
+ if (!lv_remove_with_dependencies(cmd, lvl->lv, force, 0))
return 0;
}
Index: lvm2/tools/lvremove.c
===================================================================
--- lvm2.orig/tools/lvremove.c
+++ lvm2/tools/lvremove.c
@@ -26,7 +26,7 @@ static int lvremove_single(struct cmd_co
if (lv_is_cow(lv) && lv_is_virtual_origin(origin = origin_from_cow(lv)))
lv = origin;
- if (!lv_remove_with_dependencies(cmd, lv, arg_count(cmd, force_ARG))) {
+ if (!lv_remove_with_dependencies(cmd, lv, arg_count(cmd, force_ARG), 0)) {
stack;
return ECMD_FAILED;
}
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