From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Snitzer Date: Fri, 23 Apr 2010 10:48:08 -0400 Subject: Allowing an actively merging snapshot to be removed? In-Reply-To: <20100422233605.GB23791@agk-dp.fab.redhat.com> References: <20100407200443.26841.qmail@sourceware.org> <20100419223820.GA11273@redhat.com> <20100419232509.GG4828@agk-dp.fab.redhat.com> <20100421063504.GA10083@redhat.com> <20100421193804.GA28717@redhat.com> <20100422233605.GB23791@agk-dp.fab.redhat.com> Message-ID: <20100423144808.GA21974@redhat.com> List-Id: To: lvm-devel@redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Thu, Apr 22 2010 at 7:36pm -0400, Alasdair G Kergon 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 --- 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; }