git: sys/vfs/hammer: Properly set mirror_tid on root node split

[Tomohiro Kusumi]

commit f0b930f314d1ccc165af3f9fe5f2512343fc9482
Author: Tomohiro Kusumi <kusumi.tomohiro at gmail.com>
Date:   Tue Mar 10 20:09:36 2015 +0900

    sys/vfs/hammer: Properly set mirror_tid on root node split
    
    - Set elms[0].internal.mirror_tid of the new root node
      after root split.
    
    - Without this commit elms[0].internal.mirror_tid of the new root
      node is 0 which is not appropriate given that its children have
      non-zero mirror_tid.
    
    - Submit #2801
    
    - Following hammer show results shows difference.
    
      /* the root node right after root split without this commit */
           NODE 8000000020801000 cnt=02 p=0000000000000000 type=I depth=0 mirror 00000001000087a0 fill=z8:65=1% {
      G------ ELM  0 L lo=00000000 obj=8000000000000000 rt=00 key=8000000000000000 ot=00
                     d tids 0000000000000001:0000000000000001 suboff=8000000020800000 mirror 0000000000000000
      G------ ELM  1 L lo=00000001 obj=0000000080000209 rt=01 key=0000000000000000 ot=00
                       tids 0000000100008420:0000000000000000 suboff=8000000020802000 mirror 00000001000087a0
      G------ RBN  2 ? lo=ffffffff obj=7fffffffffffffff rt=ffff key=7fffffffffffffff ot=00
                       tids ffffffffffffffff:0000000000000000 suboff=0000000000000000 mirror 0000000000000000
           }
      BM   NODE 8000000020800000 cnt=32 p=8000000020801000 type=L depth=1 mirror 00000001000087a0 fill=z8:65=1%
      ...
    
      /* the root node right after root split with this commit */
           NODE 8000000020801000 cnt=02 p=0000000000000000 type=I depth=0 mirror 00000001000087a0 fill=z8:65=1% {
      G------ ELM  0 L lo=00000000 obj=8000000000000000 rt=00 key=8000000000000000 ot=00
                     d tids 0000000000000001:0000000000000001 suboff=8000000020800000 mirror 00000001000087a0
      G------ ELM  1 L lo=00000001 obj=0000000080000209 rt=01 key=0000000000000000 ot=00
                       tids 0000000100008420:0000000000000000 suboff=8000000020802000 mirror 00000001000087a0
      G------ RBN  2 ? lo=ffffffff obj=7fffffffffffffff rt=ffff key=7fffffffffffffff ot=00
                       tids ffffffffffffffff:0000000000000000 suboff=0000000000000000 mirror 0000000000000000
           }
           NODE 8000000020800000 cnt=32 p=8000000020801000 type=L depth=1 mirror 00000001000087a0 fill=z8:65=1% {
      ...

Summary of changes:
 sys/vfs/hammer/hammer_btree.c | 2 ++
 1 file changed, 2 insertions(+)

http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/f0b930f314d1ccc165af3f9fe5f2512343fc9482


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