zfs code - Sep 2010 - need help on dnode_special_open()

Hi,

The function dnode_special_open had dnode_handle_t * as fourth argument.

dnode_t * dnode_special_open(objset_t *os, dnode_phys_t *dnp, uint64_t 
object, dnode_handle_t *dnh)

But we send address of dnode_phys_t, while calling the function, in 
usr/src/uts/common/fs/zfs/dmu_objset.c
    390     DMU_META_DNODE(os) = dnode_special_open(os,
    391         &os->os_phys->os_meta_dnode, DMU_META_DNODE_OBJECT,
    392         &os->os_meta_dnode);

whereas, dnode_handle_t is defined as:

    237 typedef struct dnode_handle {
    238     /* Protects dnh_dnode from modification by dnode_move(). */
    239     zrlock_t dnh_zrlock;
    240     dnode_t *dnh_dnode;
    241 } dnode_handle_t;

It looks strange to me as to how dnode_phys_t * is mapped to 
dnode_handle_t *, when these structures are totally different. Am I 
making a silly mistake reading the code? Please help.

Thanks in advance,
Nagaraj.

My bad. I figured it out. I was looking at (objset_phys_t)os, I should 
have looked at os as (objset_t).

Thanks,
Nagaraj.

Nagaraj Yedathore (from home) wrote:
> Hi,
>
> The function dnode_special_open had dnode_handle_t * as fourth argument.
>
> dnode_t * dnode_special_open(objset_t *os, dnode_phys_t *dnp, uint64_t 
> object, dnode_handle_t *dnh)
>
> But we send address of dnode_phys_t, while calling the function, in 
> usr/src/uts/common/fs/zfs/dmu_objset.c
>    390     DMU_META_DNODE(os) = dnode_special_open(os,
>    391         &os->os_phys->os_meta_dnode,
DMU_META_DNODE_OBJECT,
>    392         &os->os_meta_dnode);
>
> whereas, dnode_handle_t is defined as:
>
>    237 typedef struct dnode_handle {
>    238     /* Protects dnh_dnode from modification by dnode_move(). */
>    239     zrlock_t dnh_zrlock;
>    240     dnode_t *dnh_dnode;
>    241 } dnode_handle_t;
>
> It looks strange to me as to how dnode_phys_t * is mapped to 
> dnode_handle_t *, when these structures are totally different. Am I 
> making a silly mistake reading the code? Please help.
>
> Thanks in advance,
> Nagaraj.
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