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Btrfs: use received_uuid of parent during send

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Neil Horman pointed out a problem where if he did something like this

receive A
snap A B
change B
send -p A B

and then on another box do

recieve A
receive B

the receive B would fail because we use the UUID of A for the clone sources for
B.  This makes sense most of the time because normally you are sending from the
original sources, not a received source.  However when you use a recieved subvol
its UUID is going to be something completely different, so if you then try to
receive the diff on a different volume it won't find the UUID because the new A
will be something else.  The only constant is the received uuid.  So instead
check to see if we have received_uuid set on the root, and if so use that as the
clone source, as btrfs receive looks for matches either in received_uuid or
uuid.  Thanks,

Reported-by: Neil Horman <nhorman@redhat.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Reviewed-by: Hugo Mills <hugo@carfax.org.uk>
Signed-off-by: Chris Mason <clm@fb.com>
This commit is contained in:
Josef Bacik 2015-06-04 17:17:25 -04:00 committed by Chris Mason
parent 0eeff2362b
commit 37b8d27de5
1 changed files with 21 additions and 4 deletions
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19
fs/btrfs/send.c
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@ -2356,8 +2356,12 @@ static int send_subvol_begin(struct send_ctx *sctx)
TLV_PUT_U64(sctx, BTRFS_SEND_A_CTRANSID,
le64_to_cpu(sctx->send_root->root_item.ctransid));
if (parent_root) {
if (!btrfs_is_empty_uuid(parent_root->root_item.received_uuid))
TLV_PUT_UUID(sctx, BTRFS_SEND_A_CLONE_UUID,
sctx->parent_root->root_item.uuid);
parent_root->root_item.received_uuid);
else
TLV_PUT_UUID(sctx, BTRFS_SEND_A_CLONE_UUID,
parent_root->root_item.uuid);
TLV_PUT_U64(sctx, BTRFS_SEND_A_CLONE_CTRANSID,
le64_to_cpu(sctx->parent_root->root_item.ctransid));
}
@ -4586,6 +4590,19 @@ verbose_printk("btrfs: send_clone offset=%llu, len=%d, clone_root=%llu, "
if (ret < 0)
goto out;
/*
* If the parent we're using has a received_uuid set then use that as
* our clone source as that is what we will look for when doing a
* receive.
*
* This covers the case that we create a snapshot off of a received
* subvolume and then use that as the parent and try to receive on a
* different host.
*/
if (!btrfs_is_empty_uuid(clone_root->root->root_item.received_uuid))
TLV_PUT_UUID(sctx, BTRFS_SEND_A_CLONE_UUID,
clone_root->root->root_item.received_uuid);
else
TLV_PUT_UUID(sctx, BTRFS_SEND_A_CLONE_UUID,
clone_root->root->root_item.uuid);
TLV_PUT_U64(sctx, BTRFS_SEND_A_CLONE_CTRANSID,