Add a "yum_fs_snapshot_<trans_id>_<origin_volume>" LVM tag to LVM-based
snapshots (old or thinp). These tags will allow tools (e.g snapper) to
link the pre and post snapshot volumes together.
yum_fs_snapshot_trans_id() uses the first 16 digits of the hash() of the
rpm TransactionSet instance to establish a unique id that is common to
both the pretrans_hook() and posttrans_hook() -- this is quite the hack;
I'm open to using other (more future-proof) methods.
Factored add_lvm_tag_to_snapshot() out to allow for reuse.
Signed-off-by: Mike Snitzer <msnitzer@fedoraproject.org>
---
plugins/fs-snapshot/fs-snapshot.py | 29 +++++++++++++++++++++++------
1 file changed, 23 insertions(+), 6 deletions(-)
diff --git a/plugins/fs-snapshot/fs-snapshot.py b/plugins/fs-snapshot/fs-snapshot.py
index 32a1f17..22582aa 100644
--- a/plugins/fs-snapshot/fs-snapshot.py
+++ b/plugins/fs-snapshot/fs-snapshot.py
@@ -43,6 +43,12 @@ lvm_key = "create_lvm_snapshot"
dm_snapshot_merge_checked = 0
dm_snapshot_merge_support = 0
+def yum_fs_snapshot_trans_id(ts):
+ # return pseudo yum transaction id string
+ # this string is identical for both {pre,post}trans_hook
+ yum_ts_hash = "%d" % abs(hash(ts.ts))
+ return "yum_fs_snapshot_" + yum_ts_hash[:16]
+
def _fail(msg):
raise PluginYumExit(msg)
@@ -221,6 +227,14 @@ def _create_btrfs_snapshot(conduit, snapshot_tag, volume):
return 1
return 2
+def add_lvm_tag_to_snapshot(conduit, tag, snap_volume):
+ p = Popen(["/sbin/lvchange", "--addtag", tag, snap_volume],
+ stdout=PIPE, stderr=PIPE)
+ err = p.wait()
+ if err:
+ conduit.error(1, "fs-snapshot: couldn't add tag to snapshot: %s" %
+ snap_volume)
+
def _create_lvm_snapshot(conduit, snapshot_tag, volume):
"""
Create LVM snapshot LV and tag it with $snapshot_tag.
@@ -248,6 +262,8 @@ def _create_lvm_snapshot(conduit, snapshot_tag, volume):
mntpnt = volume["mntpnt"]
kern_inst = True # Default to saying it might be.
ts = conduit._base.rpmdb.readOnlyTS()
+ # save pseudo yum transaction id
+ yum_trans_id = yum_fs_snapshot_trans_id(ts)
kern_pkgtup = yum.misc.get_running_kernel_pkgtup(ts)
del ts
if kern_pkgtup is not None:
@@ -260,6 +276,7 @@ def _create_lvm_snapshot(conduit, snapshot_tag, volume):
" being altered /boot may need to be manually restored\n"
" in the event that a system rollback proves necessary.\n")
+ orig_lvname = device.split('/')[3]
snap_device = device + "_" + snapshot_tag
snap_lvname = snap_device.split('/')[3]
conduit.info(1, "fs-snapshot: snapshotting %s (%s): %s" %
@@ -278,12 +295,11 @@ def _create_lvm_snapshot(conduit, snapshot_tag, volume):
# Add tag ($snapshot_tag) to snapshot LV
# - should help facilitate merge of all snapshot LVs created
# by a yum transaction, e.g.: lvconvert --merge @snapshot_tag
- p = Popen(["/sbin/lvchange", "--addtag", snapshot_tag, snap_device],
- stdout=PIPE, stderr=PIPE)
- err = p.wait()
- if err:
- conduit.error(1, "fs-snapshot: couldn't add tag to snapshot: %s" %
- snap_device)
+ if add_lvm_tag_to_snapshot(conduit, snapshot_tag, snap_device):
+ return 1
+ # Add tag to allow other tools (e.g. snapper) to link pre
+ # and post snapshot LVs together
+ if add_lvm_tag_to_snapshot(conduit, yum_trans_id + "_" + orig_lvname, snap_device):
return 1
return 2
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