Page Cache Address Space Concept

[piyush moghe]

While going through Page Cache explanation in "Professional Linux Kernel"
book I came across one term called "address space" ( not related to virtual
or physical address space )

I did not get what is the meaning of this address space, following is
verbatim description:

"To manage the various target objects that can be processed and cached in
whole pages, the kernel uses an abstraction of
the "address space" that associates the pages in memory with a specific
block device (or any other system unit or part of a
system unit).
This type of address space must not be confused with the virtual and
physical address spaces provided by the
system or processor. It is a separate abstraction of the Linux kernel that
unfortunately bears the same name.
Initially, we are interested in only one aspect. Each address space has a
"host" from which it obtains its data. In most
cases, these are inodes that represent just one file.[2] Because all
existing inodes are linked with their superblock (as
discussed in Chapter 8), all the kernel need do is scan a list of all
superblocks and follow their associated inodes to obtain
a list of cached pages"


Can anyone please explain what is the use of this and what this is all
about?

Regards,
Piyush
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