On Tue, 2011-05-24 at 18:56 +0300, Boaz Harrosh wrote:
> In the nfs_pageio_descriptor passed to pg_test() together with the two pages:
> Which member means the current byte_size (or page_count?) and what is the
> meaning of some of these fields
>
> struct nfs_pageio_descriptor {
> ....
> unsigned long pg_bytes_written;
> Is this for result after read/write?
This is the total number of bytes we successfully called
nfs_pageio_doio() for. In other words, it should represent the total
number of bytes we put on the wire.
> size_t pg_count;
> Is this the number of pages added up to now?
> Do we also have the start of the first page?
This is the number of bytes we have successfully coalesced into the
current i/o.
> size_t pg_bsize;
> So I understand this is the max allowed pages. Does
> that mean also the allocated size or Just the negotiated
> size with the server? (Really bad name if you ask me)
It means the 'block size'. In ordinary NFS parlance that will be the
'rsize' or the 'wsize'.
> unsigned int pg_base;
> Is that the index of the first page? That cannot be, the page->index
> needs to be 64bit. So what is this then?
It is used when dealing with I/O requests that are not page aligned.
If you consider the pages that we are to write out in the current I/O as
a single buffer, then the pg_base is the offset of the first byte to
write out/read in.
--
Trond Myklebust
Linux NFS client maintainer
NetApp
Trond.Myklebust@xxxxxxxxxx
www.netapp.com
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