RE: ubifs: read bad node type in ubifs_tnc_read_wbuf

[李傲傲 (Carson Li1/9542) <Carson.Li1@xxxxxxxxxx>]

On Monday, March 2, 2020 6:23 PM, Hou Tao<houtao1@xxxxxxxxxx> wrote:

>The other case is there is there is GC and journal head switch (no commit) between
>the release of tnc_mutex and the call of ubifs_read_node_wbuf(), as illustrated by
>the following stack:

>process A                       process B

>node in LEB 54 has been committed

>ubifs_tnc_locate
>zbr->lnum = 54 (find in TNC)
>mutex_unlock(&tnc_mutex)

>->GC (change zt->lnum to 224(GCHD) in _TNC_)
>->data journal head switch (zbr->lnum = 54 becomes DATAHD)

>ubifs_get_wbuf(zbr->lnum = 54) is true
>ubifs_tnc_read_node
>ubifs_get_wbuf(zbr->lnum = 54 as the DATAHD) is still true
>ubifs_read_node_wbuf

oh, it is truly another case I didn't thought about. Thanks for your explanation, and your
patch will quite perfectly make sense for me now : ) .

Thanks.
Carson


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