netfilter: nf_tables: drop map element references from preparation phase

stable inclusion
from stable-v5.10.188
commit a136b7942ad2a50de708f76ea299ccb45ac7a7f9
bugzilla: https://gitee.com/openeuler/kernel/issues/I86JB6

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a136b7942ad2a50de708f76ea299ccb45ac7a7f9



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[ Upstream commit 628bd3e4 ]

set .destroy callback releases the references to other objects in maps.
This is very late and it results in spurious EBUSY errors. Drop refcount
from the preparation phase instead, update set backend not to drop
reference counter from set .destroy path.

Exceptions: NFT_TRANS_PREPARE_ERROR does not require to drop the
reference counter because the transaction abort path releases the map
references for each element since the set is unbound. The abort path
also deals with releasing reference counter for new elements added to
unbound sets.

Fixes: 59105446 ("netfilter: nf_tables: revisit chain/object refcounting from elements")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Lu Wei <luwei32@huawei.com>