[Lustre-devel] LNET:where in the code dose the file obeject's private data gets filled up.

[Liang Zhen]

ankit sharma wrote:
> Hi all,
>         I am new to Lustre code. So i am sorry if my question is 
> trivial or silly.
>
> My question:
>
> On line number 116 of the file lnet/lnet/router_proc.c
> variable ver_p is getting set from the proc file object's private data.
>
> Can any one tell me which part of the lustre code dose this file 
> object private data
> gets initialized / set .
>
> conceptually in can imagine it should (correct me if I am worng) be 
> set in open call of the file ( /proc/sys/lnet/routers )
>
> BUT I cant locate the Lustre code that dose that(sets the private data 
> of file object).
>    
>
> code snippet form lnet/lnet/router_proc.c
>
> int LL_PROC_PROTO(proc_lnet_routes)
> {
>         int        rc     = 0;
>         char      *tmpstr;
>         char      *s;
>         const int  tmpsiz = 256;
>         int        len;
>         int       *ver_p  = (unsigned int *)(&filp->private_data);
>
>         DECLARE_LL_PROC_PPOS_DECL;
>
>         LASSERT (!write);
>
>         if (*lenp == 0)
>                 return 0;
>
>         LIBCFS_ALLOC(tmpstr, tmpsiz);
>         if (tmpstr == NULL)
>                 return -ENOMEM;
>
>         s = tmpstr; /* points to current position in tmpstr[] */
>
>         if (*ppos == 0) {
>                 s += snprintf(s, tmpstr + tmpsiz - s, "Routing %s\n",
>                               the_lnet.ln_routing ? "enabled" : 
> "disabled");
>                 LASSERT (tmpstr + tmpsiz - s > 0);
>
>                 s += snprintf(s, tmpstr + tmpsiz - s, "%-8s %4s %7s %s\n",
>                               "net", "hops", "state", "router");
>                 LASSERT (tmpstr + tmpsiz - s > 0);
>
>                 LNET_LOCK();
>                 *ver_p = (unsigned int)the_lnet.ln_remote_nets_version;

It's initialized at here, because we have "*ppos == 0" while starting, 
so it's actually same as
filp->private_data = (void *)the_lnet.ln_remote_nets_version;


Regards
Liang


>                 LNET_UNLOCK();
>
> } else {
>                 struct list_head  *n;
>                 struct list_head  *r;
>                 lnet_route_t      *route = NULL;
>                 lnet_remotenet_t  *rnet  = NULL;
>                 int                skip  = *ppos - 1;
>
>                 LNET_LOCK();
>
>                 if (*ver_p != (unsigned 
> int)the_lnet.ln_remote_nets_version) {
>                         LNET_UNLOCK();
>                         LIBCFS_FREE(tmpstr, tmpsiz);
>                         return -ESTALE;
>                 }
>
>                 n = the_lnet.ln_remote_nets.next;
>
>
>
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>
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