orangefs: remember count when reading.
Orangefs wins when it can do IO on large (up to four meg) blocks at a time,
and looses when it has to do tiny "small io" reads and writes. Accessing
Orangefs through the pagecache with the kernel module helps with small io,
both reading and writing, a great deal. Readpage generally tries to fetch a
page (four k) at a time. We'll let users use "count" (as in read(2) or
pread(2) for example) as a knob to control how much data they get from
Orangefs at a time and we'll try to use the data to fill extra
pagecache pages when we get to ->readpage, hopefully resulting in
fewer calls to readpage and Orangefs userspace.
We need a way to remember how they set count so that we can still have
it available when we get to ->readpage.
- We'll use file->private_data to keep track of "count".
We'll wrap generic_file_open with orangefs_file_open and
initialize private_data to NULL there.
- In ->read_iter we have access to both "count" and file, so
we'll kmalloc some space onto file->private_data and store
"count" there.
- We'll kfree file->private_data each time we visit ->flush and
reinitialize it to NULL.
Signed-off-by: Mike Marshall <hubcap@omnibond.com>
Signed-off-by: Martin Brandenburg <martin@omnibond.com>
2 files changed