ubifs: read bad node type in ubifs_tnc_read_wbuf

李傲傲 (Carson Li1/9542) Carson.Li1 at unisoc.com
Wed Jan 15 16:54:16 PST 2020


>LPROPS_TAKEN should avoid this.
Is it possible that a commit finishes and removes the LPROPS_TAKEN flag?
and when it is reused as a journal head, LPROPS_TAKEN flag is set again.

>If possible, can you please check the lprobs of the affected LEBs?
--------------------------------case 1----------------------------------------------
jhead[GCHD].wbuf.lnum   = 195(found in TNC)
jhead[DATAHD].wbuf.lnum  = 139(zbr passed to ubifs_tnc_read_node)

struct ubifs_lprops =
{
      free = 4096,
      dirty = 123272,
      flags = 16, //LPROPS_TAKEN
      lnum = 195,
      {
        list = {
          next = 0xcd1ad6d8,
          prev = 0xcd1ad440
        },
        hpos = -853879080
      }
    }

struct ubifs_lprops = {
      free = 124944,
      dirty = 0,
      flags = 16, //LPROPS_TAKEN
      lnum = 139,
      {
        list = {
          next = 0xc8be96c0,
          prev = 0xc90e99c8
        },
        hpos = -927033664
      }
    }

one more information about the ubifs_bud rbtree:

crash_arm> tree -t rbtree -o ubifs_bud.rb -N 0xcd196dd4 -s ubifs_bud.lnum
cd196dc0
  lnum = 195//jhead[GCHD]
c89207c0
  lnum = 60
cd196fc0
  lnum = 59
c8bd5e40
  lnum = 125
c8935600
  lnum = 97
c2aafec0
  lnum = 139//jhead[DATAHD]
c8bb2140
  lnum = 279//jhead[BASEHD]
c8ee8d00
  lnum = 239
cd196980
  lnum = 348
--------------------------------------case 2----------------------------------------
jhead[GCHD].wbuf.lnum   = 224(found in TNC)
jhead[DATAHD].wbuf.lnum  = 54(zbr passed to ubifs_tnc_read_node)

struct ubifs_lprops =
{
      free = 24576,
      dirty = 127640,
      flags = 16, //LPROPS_TAKEN
      lnum = 224,
      {
        list = {
          next = 0xc9014ec0,
          prev = 0xc91ed0c0
        },
        hpos = -922661184
      }
 }
struct ubifs_lprops =
{
      free = 45952,
      dirty = 0,
      flags = 16, //LPROPS_TAKEN
      lnum = 54,
      {
        list = {
          next = 0xcd1d4328,
          prev = 0xc90ea9c8
        },
        hpos = -853720280
      }
    }

crash_arm> tree -t rbtree -o ubifs_bud.rb -N 0xc6afae14 -s ubifs_bud.lnum
c6afae00
  lnum = 88
c8fa5540
  lnum = 53//jhead[BASEHD]
c916b500
  lnum = 42
c8f8b140
  lnum = 62
c2a953c0
  lnum = 54//jhead[DATAHD]
c916b480
  lnum = 215
c2ac0040
  lnum = 120
c916b400
  lnum = 224//jhead[GCHD]
c6b02f80
  lnum = 271

By the way, there is another timing the LEB might be garbage collected:
>     A      |              B
> --------------------------------------------------------------------------
> ubifs_tnc_locate
>   zbr->lnum = 54 (find in TNC)
>     ubifs_get_wbuf(zbr->lnum = 54) is ture
>          ubifs_tnc_read_node
>                         ->GC(change zt->lnum to 224(GCHD) in _TNC_)
>                         ->zbr->lnum = 54 becomes DATAHD
>             ubifs_get_wbuf(zbr->lnum = 54 as the DATAHD) is ture again
>             ubifs_read_node_wbuf
> --------------------------------------------------------------------------

     A      |              B
 ---------------------------------------------------------------------------
ubifs_tnc_locate
   zbr->lnum = 54 (find in TNC)
                         ->GC(change zt->lnum to 224(GCHD) in _TNC_)
                         ->zbr->lnum = 54 becomes DATAHD
     ubifs_get_wbuf(zbr->lnum = 54 as the DATAHD) is ture
          ubifs_tnc_read_node
             ubifs_get_wbuf(zbr->lnum = 54) is ture again
             ubifs_read_node_wbuf
 ---------------------------------------------------------------------------

Thanks.
Carson
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