e2fsck: decrement bad count _after_ remapping a duplicate block

e2fsck: decrement bad count _after_ remapping a duplicate block

Decrement the bad count *after* we've shown that (a) we can allocate a
replacement block and (b) remap the file block.  Unfortunately,
the only way to tell if the remapping succeeded is to wait until the
next clone_file_block() call or block_iterate3() returns.

Otherwise, there's a corruption error: we decrease the badcount once in
preparation to remap, then the remap fails (either we can't find a
replacement block or we have to split the extent tree and can't find a
new extent block), so we delete the file, which decreases the badcount
on the block a second time.  Later on e2fsck will think that it's
straightened out all the duplicate blocks, which isn't true.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>