Which is the proper way to bring in the backing store behind an inode as an struct page?

["Perez-Gonzalez, Inaky" <inaky.perez-gonzalez@intel.com>]

Hi all

Dummy question that has been evading me for the last hours. Can you
help? Please bear with me here, I am a little lost in how to deal
with inodes and the cache.

I have a problem where I have to modify a value in user space from 
inside a function called from do_exit() [this is for robust mutexes].
The reason for this is when a task exits holding a mutex, it needs to
update the user space word that represents the mutex to indicate that
it is dead. This is needed to allow for fast-lock operations when 
there is no mutex contention.

I need to be able to kmap the location where the page is so I can
modify it. The problem is that in one of the cases, when the thing 
is in a shared mapping (linear or non-linear), I just have the inode,
the page offset and the offset into the page.

Thus, what I need is a way that given the pair (inode,pgoff) 
returns to me the 'struct page *' if the thing is cached in memory or
pulls it up from swap/file into memory and gets me a 'struct page *'.

Is there a way to do this?

Thanks

Inaky Perez-Gonzalez -- Not speaking for Intel -- all opinions are my own (and my fault)

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