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snapshot: zero cow header for read-only snapshot

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When read-only snapshot was created, tool was skipping header
initialization of cow device.  If it happened device has been
already containing header from some previous snapshot, it's
been 'reused' for a newly created snapshot instead of being cleared.
This commit is contained in:
Zdenek Kabelac 2014-02-26 00:17:11 +01:00
parent 3bb9eda97c
commit 2b044452e3
3 changed files with 18 additions and 2 deletions
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1
WHATS_NEW
View File

@ -1,5 +1,6 @@
Version 2.02.106 -
====================================
Zero snapshot COW header when creating read-only snapshot.
Comment out config lines in dumpconfig output without default values defined.
Improve detection of clustered mirror support.
Enhance raid code with feature flags, for now checks for raid10.

11
test/shell/snapshot-usage.sh
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@ -131,4 +131,15 @@ vgremove -ff $vg1
fi
lvremove -f $vg
# Check snapshot really deletes COW header for read-only snapshot
aux lvmconf "allocation/wipe_signatures_when_zeroing_new_lvs = 1"
lvcreate -L10 -n $lv1 $vg
lvcreate -s -L10 -n snap $vg/$lv1
# Populate snapshot with some filesystem signatures
mkfs.ext4 "$DM_DEV_DIR/$vg/snap"
lvremove -f $vg/snap
lvcreate -s -pr -l12 -n snap $vg/$lv1
vgremove -ff $vg

6
tools/lvcreate.c
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@ -769,8 +769,12 @@ static int _read_activation_params(struct lvcreate_params *lp,
lp->permission = arg_uint_value(cmd, permission_ARG,
LVM_READ | LVM_WRITE);
if (lp->snapshot) {
/* Snapshot has to zero COW header */
lp->zero = 1;
lp->wipe_signatures = 0;
} else if (!(lp->permission & LVM_WRITE)) {
/* Must not zero/wipe read only volume */
if (!(lp->permission & LVM_WRITE)) {
lp->zero = 0;
lp->wipe_signatures = 0;
}