Re: VNOP_PAGEIN doubt
Re: VNOP_PAGEIN doubt
- Subject: Re: VNOP_PAGEIN doubt
- From: Terry Lambert <email@hidden>
- Date: Wed, 23 Sep 2009 02:32:34 -0700
On Sep 23, 2009, at 1:20 AM, anubhav rakshit < email@hidden> wrote: On Wed, Sep 23, 2009 at 1:30 PM, anubhav rakshit <email@hidden> wrote: On Wed, Sep 23, 2009 at 1:17 PM, Michael Smith <email@hidden> wrote:
On Sep 23, 2009, at 12:34 AM, anubhav rakshit wrote: I am working on a VFS plugin.From the VNOP_PAGEIN callback is it somehow possible to know the access type for the pagein request.
For example if my pagein function is called afs_pagein() what i want to know is from the "args" is it possible to find out the access type?
What do you mean by "access type"? Do you mean the direction of the data transfer, or the protection on the resulting pages, or something else?
Yes i am asking about the direction of the data transfer.
I goofed up. I needed to know the protection.
You mention afs in passing; are you asking in hopes of delaying an over-the-wire open? As soon as a file system vends a vnode out to the VFS layer, the file is for all intents and purposes open until the VFS layer decides to vrele it back to you so you can do whatever with the FS specific information hung off the v_data and vrele the vnode itself back to the shared vnode pool. If you vend it, you need to be prepared to take any subsequent VNOP calls and handle them for as long as the vnode stays vended. So no delayed or implied opens allowed: you vend it or you fail the lookup.
-- Terry |
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