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vg/snapshotN should not appear anywhere.
No code should be showing this, but it was noticed in some logs last
week and we can deal with it in display_lvname().
Add new test for lv_is_snapshot().
Also move few other bitchecks into same place as remaining bit tests.
TODO: drop lv_is_merging_origin() and keep using lv_is_merging().
Use lv_is_* macros throughout the code base, introducing
lv_is_pvmove, lv_is_locked, lv_is_converting and lv_is_merging.
lv_is_mirror_type no longer includes pvmove.
Create a separate function to validation snapshot min chunk value
and relocate code into snapshot_manip file.
This function will be shared with lvconvert then.
Condition was swapped - however since it's been based on 'random'
memory content it's been missed as attribute has not been set.
So now we have quite a few possible results when testing.
We have old status without separate metadata and
we have kernels with fixed snapshot leak bug.
(in-release update)
Code uses target driver version for better estimation of
max size of COW device for snapshot.
The bug can be tested with this script:
VG=vg1
lvremove -f $VG/origin
set -e
lvcreate -L 2143289344b -n origin $VG
lvcreate -n snap -c 8k -L 2304M -s $VG/origin
dd if=/dev/zero of=/dev/$VG/snap bs=1M count=2044 oflag=direct
The bug happens when these two conditions are met
* origin size is divisible by (chunk_size/16) - so that the last
metadata area is filled completely
* the miscalculated snapshot metadata size is divisible by extent size -
so that there is no padding to extent boundary which would otherwise
save us
Signed-off-by:Mikulas Patocka <mpatocka@redhat.com>
Drop find_merging_snapshot() function. Use find_snapshot()
called after check for lv_is_merging_origin() which
is the commonly used code path - so we avoid duplicated
tests and potential risk of derefering NULL point
in unhandled error path.
Revert 4777eb6872 which put
target_present check into init_snapshot_merge(). However
this function is also used when parsing metadata. So we would
get this present test performed even when target is not really
needed. So move this target_present test directly into lvconvert.
Since the virtual snapshot has no reason to stay alive once we
detach related snapshot - deactivate whole thing in front of
snapshot removal - otherwice the code would get tricky for
support in cluster.
The correct full solution would require to have transactions
for libdm operations.
Also enable to the check for snapshot being opened prior
the origin deactivation, otherwise we could easily end
with the origin being deactivate, but snapshot still kept
active, desynchronizing locking state in cluster.
Activation is needed only for clustered VG.
For non-clustered VG skip activation, since deactivate_lv()
is called without problems (no testing for lock presence).
(updates f6ded62291)
When the merging of snapshot is finished, we need to clean dm table
intries for snapshot and -cow device. So for merging snapshot
we have to activate_lv plain 'cow' LV and let the table
resolver to its work - shortly deactivation_lv() request
will follow - in cluster this needs LV lock to be held by clvmd.
Also update a test - add small wait - if lvremove is not 'fast enough'
and merging process has not been stopped and $lv1 removed in background.
Ortherwise the following lvcreate occasionally finds name $lv1 still in use.
(in release fix)
Support for exclusive activation of snapshots revealed some problems.
When snapshot is created, COW LV is activated first (for clearing) and
then it's transformed into snapshot's COW LV, but it has left the lock
for such LV active in cluster and this lock could not have been removed
from dlm, unless snapshot has been removed within same dlm session.
If the user tried to remove snapshot after rebooting node, the lock was
missing, and COW LV could not have been detached.
Patch modifes the approach in this way:
Always deactivate COW LV for clustered vg after clearing (so it's
activated again via imlicit snapshot activation rule when snapshot is activated).
When snapshot is removed, activate COW LV as independend LV, so the lock
will exist for such LV, but only when the snapshot is active.
Also add test case for testing snapshot removal after cluster reboot.
teardown sequence. (Previously the snapshot was deactivated while its
origin was active and before its removal was committed to disk, so
restarting after a crash at the point would leave corruption.)
Add a merging snapshot to the deptree, using the "error" target, rather
than avoid adding it entirely. This allows proper cleanup of the -cow
device without having to rename the -cow to use the origin's name as a
prefix.
Move the preloading of the origin LV, after a merge, from
lv_remove_single() to vg_remove_snapshot(). Having vg_remove_snapshot()
preload the origin allows the -cow device to be released so that it can
be removed via deactivate_lv(). lv_remove_single()'s deactivate_lv()
reliably removes the -cow device because the associated snapshot LV,
that is to be removed when a snapshot-merge completes, is always added
to the deptree (and kernel -- via "error" target).
Now when the snapshot LV is removed both the -cow and -real devices
get removed using uuid rather than device name. This paves the way
for us to switch over to info-by-uuid queries.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Eliminate 'merging_snapshot' from 'struct logical_volume' and just use
'snapshot' for origin lv's reference to the merging snapshot; also set
MERGING in the origin lv's status.
Make 'merging_snapshot' pointer that points from the origin to the
segment that represents the merging snapshot.
Import/export 'merging_store' metadata.
Do not allow creating snapshots while another snapshot is merging.
Snapshot created in this state would certainly contain invalid data.
NOTE: patches at the end of this series will remove 'merging_snapshot'
and will introduce helpful wrappers and cleanups.
The vg->lv_count parameter now includes always number of visible
logical volumes.
Note that virtual snapshot volume (snapshotX) is never visible,
but it is stored in metadata with visible flag.
The snapshot segment (snapshotX) is created twice
during the text metadata segment processing.
This can cause temporary violation of max_lv count.
Simplify the code, snapshot segment is properly initialized
in init_snapshot_seg function now and do not need to be replaced
by vg_add_snapshot call.
The vg_add_snapshot() is now usefull only for adding new
snapshot and it shares the same initialization function.
The snapshot name is always generated, name paramater can be
removed from function call.
Add lvs origin_size field.
Fix linux configure --enable-debug to exclude -O2.
Still a few rough edges, but hopefully usable now:
lvcreate -s vg1 -L 100M --virtualoriginsize 1T
Patch fixes these problems:
- during the snapshot creation process, it needs create 2 LVs,
one is cow, second becomes snapshot.
If the code fails in vg_add_snapshot, code lvcreate will not remove
LV cow volume.
- if max_lv is set and VG contains snapshot, it can happen that
during the activation lv_count is temporarily increased over the limit
and VG metadata are not properly processed
see https://bugzilla.redhat.com/show_bug.cgi?id=490298
- vgcfgrestore alows restore with max_lv set to lower valuer that actual
LV count. This later leads to situation that max_lv is completely ignored.
- vgck doesn't call vg_validate(). It should at least try:-)
Signed-off-by: Milan Broz <mbroz@redhat.com>
