Re: [RFC] sane access to per-fs metadata (was Re: [PATCH] Documentatio

[Kai Henningsen]

[EMAIL PROTECTED] (Chip Salzenberg)  wrote on 01.04.01 in :

> Why not have a kernel thread and use standard RPC techniques like
> sockets?  Then you'd not have to invent anything unimportant like
> Yet Another IPC Technique.

You can, of course, transfer the exact same RPC messages over a file  
descriptor on your metadata fs. It doesn't *have* to be ASCII, especially  
not for purely internal-use interfaces.

And for ioctl() fans, you could transfer the exact same data via read()/ 
write() again. That's not significantly harder. Especially if you write a  
wrapper around the calls. If you want to be perverse, you can probably  
even transmit user space pointers.

But I suspect there are really only two generally useful interfaces:

1. A text based interface for generally-useful stuff you might want to  
manipulate from the shell, or random user programs. (From the shell _is_  
random user programs.)

2. A RPC based interface for tightly-coupled fs utilities. (I don't know  
off the top of my head what the kernel already has - ISTR networking has  
_something_.)

Don't forget a version marker of some kind. Sooner or later, you'll be  
glad you have it.

MfG Kai
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Re: [RFC] sane access to per-fs metadata (was Re: [PATCH] Documentatio

[Kai Henningsen]

[EMAIL PROTECTED] (Chip Salzenberg)  wrote on 01.04.01 in E14jdkF-0007Ps-00@tytlal:

 Why not have a kernel thread and use standard RPC techniques like
 sockets?  Then you'd not have to invent anything unimportant like
 Yet Another IPC Technique.

You can, of course, transfer the exact same RPC messages over a file  
descriptor on your metadata fs. It doesn't *have* to be ASCII, especially  
not for purely internal-use interfaces.

And for ioctl() fans, you could transfer the exact same data via read()/ 
write() again. That's not significantly harder. Especially if you write a  
wrapper around the calls. If you want to be perverse, you can probably  
even transmit user space pointers.

But I suspect there are really only two generally useful interfaces:

1. A text based interface for generally-useful stuff you might want to  
manipulate from the shell, or random user programs. (From the shell _is_  
random user programs.)

2. A RPC based interface for tightly-coupled fs utilities. (I don't know  
off the top of my head what the kernel already has - ISTR networking has  
_something_.)

Don't forget a version marker of some kind. Sooner or later, you'll be  
glad you have it.

MfG Kai
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/