LU-17337 osd: ask for more revoke credits

LU-17337 osd: ask for more revoke credits

starting from 4.* kernels JBD2 tracks number of potential
revoked blocks separately from regular journal blocks and
checks a transaction doesn't exceed the declared number.
before extent merging patch a regular block allocation could
free only very limited number of blocks. now with extent
merging when an extent tree is really big and few extents
are inserted in a single transaction, then such an allocation
can exceed default revoke credits (8).
the patch uses number of extent in the transaction to calculate
potential number of revoke records (max tree depth * default).

Fixes: 0f7e6c02a9 ("LU-16843 ldiskfs: merge extent blocks")
Signed-off-by: Alex Zhuravlev <bzzz@whamcloud.com>
Change-Id: I4967deb56e5aba82b68ffdc91de589fffae6a64a
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/53325
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Li Dongyang <dongyangli@ddn.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>