git: sys/vfs/hammer: Fix/rewrite hammer_free_freemap()

[Tomohiro Kusumi]

commit de75bb26d7216c20f9ddfe67784f7dce051bd11c
Author: Tomohiro Kusumi <kusumi.tomohiro at gmail.com>
Date:   Fri Mar 11 23:49:15 2016 +0900

    sys/vfs/hammer: Fix/rewrite hammer_free_freemap()
    
    This commit rewrites hammer_free_freemap() used by hammer volume-del
    in order to handle layer2 layout change by the previous commit.
    
    The functional difference (other than the layout difference) is
    that this commit through for-loop twice. This is to separate
    counting busy layer2 and zero clearing layer1. Layer1 zero clear
    should be done only when all layer2 are empty, so no ondisk change
    occurs until it's ready to erase ondisk layer1. It previously had
    these two in the same loop, which means if the volume consisted
    of >1 layer1 it could happen to find out the volume wasn't ready
    to remove after it has zero cleared layer1 entry(s).
    
    This commit adds prototype for hammer_iterate_l1l2_entries().
    This was added only to avoid compile error for not using it.
    hammer_iterate_l1l2_entries() will be removed in the next commit.
    (Removing it in this same commit makes default git diff without
    any option unclear)
    
    This commit does not affect a volume that was previously added
    by hammer volume-add when removing that volume via hammer volume-del
    after this commit. HAMMER reads layer2 offset from ondisk layer1
    entries (and layer1 layout hasn't changed), so the change made by
    the previous commit to conform to the original design doesn't
    depend on the code once it's added.

Summary of changes:
 sys/vfs/hammer/hammer_volume.c | 169 ++++++++++++++++++++++++++---------------
 1 file changed, 107 insertions(+), 62 deletions(-)

http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/de75bb26d7216c20f9ddfe67784f7dce051bd11c


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