RE: ubifs: read bad node type in ubifs_tnc_read_wbuf

["李傲傲 (Carson Li1/9542)" <Carson.Li1@unisoc.com>]

Hi Richard:
I am sorry that I had sent an email to the linux-mtd but find out
I did not copy to you. Now I resend it again, please kindly check it
and reply me.

>>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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