reiserfs: workaround for dead loop in finish_unfinished

There is possible dead loop in finish_unfinished function.

In most situation, the call chain iput -> ...  -> reiserfs_delete_inode ->
remove_save_link will success.  But for some reason such as data
corruption, reiserfs_delete_inode fails on reiserfs_do_truncate ->
search_for_position_by_key.

Then remove_save_link won't be called.  We always get the same
"save_link_key" in the while loop in finish_unfinished function.  The
following patch adds a check for the possible dead loop and just remove
save link when deap loop.

[akpm@linux-foundation.org: cleanups]
Signed-off-by: Lepton Wu <ytht.net@gmail.com>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Jeff Mahoney <jeffm@suse.com>
Cc: "Vladimir V. Saveliev" <vs@namesys.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>