Hi Jens,
On Thu, 5 Mar 2009, Jens Axboe wrote:
> On Wed, Mar 04 2009, Geert Uytterhoeven wrote:
> > Below is the rewrite of the PS3 Video RAM Storage Driver as a plain block
> > device, as requested by Arnd Bergmann.
> >
> > The MTD-based PS3 Video RAM Storage Driver was integrated into the mainline
> > kernel in 2.6.29-rc1.
> >
> > Ideally, we think it would be best if the existing MTD-based ps3vram driver
> > would be replaced by the new block-based ps3vram driver before 2.6.29 is
> > released. This would relieve the burden of supporting two different swap
> > space
> > schemes on PS3 (swap on /dev/mtdblock0 vs. /dev/ps3vram) from the distro
> > maintainer's shoulders, as in that case there would never have been a stable
> > kernel version containing the MTD-based ps3vram driver.
> >
> > What do you think? If this is accepted, I'll submit a patch to remove the
> > MTD
> > ps3vram and add the new driver as ps3vram (instead of ps3vram-ng).
> >
> > Thanks for your (review and other) comments!
>
> I'd rewrite this as a ->make_request_fn handler instead. Then you can
> get rid of the kernel thread. IOW, change
>
> queue = blk_init_queue(ps3vram_request, &priv->lock);
>
> to
>
> queue = blk_alloc_queue(GFP_KERNEL);
> blk_queue_make_request(queue, ps3vram_make_request);
Thanks, I didn't know that part...
> Add error handling of course, and call blk_queue_max_*() to set your
> limits for this device.
I took out the blk_queue_max_*() calls (compared to ps3disk.c), as none of the
limits apply, and the defaults are fine.
Is that OK, or is it better to make it explicit?
> Then add a ps3vram_make_request() ala:
> static void ps3vram_do_request(struct request_queue *q, struct bio *bio)
> {
> struct ps3_system_bus_device *dev = q->queuedata;
> struct ps3vram_priv *priv = dev->core.driver_data;
> int write, res, err = -EIO;
> struct bio_vec *bv;
> sector_t sector;
> loff_t offset;
> size_t len, retlen;
> int i;
>
> write = bio_data_dir(bio) == WRITE;
>
> sector = bio->bi_sector;
> bio_for_each_segment(bv, bio, i) {
> char *ptr = page_address(bv->bv_page) + bv->bv_offset;
>
> len = bv->bv_len;
> offset = sector << 9;
>
> if (write)
> res = ps3vram_write(dev, offset, len, &retlen, ptr);
> else
> res = ps3vram_read(dev, offset, len, &retlen, ptr);
>
> if (res) {
> dev_err(&dev->core, "%s failed\n", op);
> goto out;
> }
>
> if (retlen != len) {
> dev_err(&dev->core, "Short %s\n", op);
> goto out;
> }
> sector += (len >> 9);
> }
>
> dev_dbg(&dev->core, "%s completed\n", op);
> err = 0;
> out:
> bio_endio(bio, err);
> }
>
> I just typed it here, so if it doesn't compile you get to keep the
> pieces :-)
OK, I'll give it a try...
BTW, does this mean the `simple' way, which I used based on LDD3, is
deprecated?
> Since ps3 is very RAM limited, I didn't bother with any highmem mapping
> for the bio, since I gather that isn't an issue on that platform. You
> may want to detail that in a comment above the page_addres() thing at
> the top of the loop, though.
PS3 is ppc64, so no highmem. But I guess I best add the code for that anyway,
in case people will copy the driver in the future (I remember receiving a
similar comment for ps3disk).
Thanks for your comments!
With kind regards,
Geert Uytterhoeven
Software Architect
Sony Techsoft Centre Europe
The Corporate Village · Da Vincilaan 7-D1 · B-1935 Zaventem · Belgium
Phone: +32 (0)2 700 8453
Fax: +32 (0)2 700 8622
E-mail: geert.uytterhoe...@sonycom.com
Internet: http://www.sony-europe.com/
A division of Sony Europe (Belgium) N.V.
VAT BE 0413.825.160 · RPR Brussels
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