ext2: dump current reservation window info

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I7TN3J



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There's report BUG in 'ext2_try_to_allocate_with_rsv()', although there's
now dump of all reservation windows information. But there's unknown which
window is being processed.So this is not helpful for locating the issue.
To better analyze the problem, dump the information about reservation window
that is being processed. And just bail with error instead of BUG here.

Signed-off-by: Ye Bin <yebin10@huawei.com>