get_inode callback of generic_fh_to_{dentry|parent}

get_inode callback of generic_fh_to_{dentry|parent}

[Marco Stornelli]

Hi,

I'm the maintainer of pramfs. I'm currently working in the export
operation for my fs and I've got a question about the callback in the
subject. Is it right that this function return an error for a not
allocated inode? I see a comment for example in the ext2 code for the
callback like this:

  /* iget isn't really right if the inode is currently unallocated!! */

So I think it's cleaner to use ilookup() instead of iget(). Comments?

Thanks.

Marco

Re: get_inode callback of generic_fh_to_{dentry|parent}

[Christoph Hellwig]

On Mon, Aug 23, 2010 at 03:32:04PM +0200, Marco Stornelli wrote:
> Hi,
> 
> I'm the maintainer of pramfs. I'm currently working in the export
> operation for my fs and I've got a question about the callback in the
> subject. Is it right that this function return an error for a not
> allocated inode? I see a comment for example in the ext2 code for the
> callback like this:
> 
>   /* iget isn't really right if the inode is currently unallocated!! */
> 
> So I think it's cleaner to use ilookup() instead of iget(). Comments?

ilookup only returns an inode if it's already in the inode cache.
the get_inode callback needs to return an inode if it's allocated, even
if it's not in the inode cache.

Re: get_inode callback of generic_fh_to_{dentry|parent}

[Marco Stornelli]

2010/8/23 Christoph Hellwig <hch@infradead.org>:
> On Mon, Aug 23, 2010 at 03:32:04PM +0200, Marco Stornelli wrote:
>> Hi,
>>
>> I'm the maintainer of pramfs. I'm currently working in the export
>> operation for my fs and I've got a question about the callback in the
>> subject. Is it right that this function return an error for a not
>> allocated inode? I see a comment for example in the ext2 code for the
>> callback like this:
>>
>>   /* iget isn't really right if the inode is currently unallocated!! */
>>
>> So I think it's cleaner to use ilookup() instead of iget(). Comments?
>
> ilookup only returns an inode if it's already in the inode cache.
> the get_inode callback needs to return an inode if it's allocated, even
> if it's not in the inode cache.
>
>

Ok, right. However, it's not necessary to allocate it if it's not yet
allocated, it just needs to check if the inode is allocated and return
it, if I well understand.
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