Date: Sat, 30 Nov 2013 17:57:01 -0500 (EST) From: Rick Macklem <rmacklem@uoguelph.ca> To: Konstantin Belousov <kostikbel@gmail.com> Cc: Kirk McKusick <mckusick@mckusick.com>, FreeBSD FS <freebsd-fs@freebsd.org> Subject: Re: RFC: NFS client patch to reduce sychronous writes Message-ID: <1288055532.23818811.1385852221143.JavaMail.root@uoguelph.ca> In-Reply-To: <20131130132233.GZ59496@kib.kiev.ua>
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Kostik wrote:
> On Thu, Nov 28, 2013 at 06:50:20PM -0500, Rick Macklem wrote:
> > obcount = np->n_size - (lbn * biosize);
> > *** This sets obcount to the byte offset within the buffer cache
> > block of
> > EOF before it is grown by this write (or file size mod biosize,
> > if you prefer)
> > bp = nfs_getcacheblk(vp, lbn, obcount, td);
> >
> > if (bp != NULL) {
> > long save;
> >
> > mtx_lock(&np->n_mtx);
> > np->n_size = uio->uio_offset + n;
> > np->n_flag |= NMODIFIED;
> > vnode_pager_setsize(vp, np->n_size);
> > *** n_size is now grown to the new EOF for after the write.
> > mtx_unlock(&np->n_mtx);
> >
> > save = bp->b_flags & B_CACHE;
> > bcount = on + n;
> > allocbuf(bp, bcount);
> > bp->b_flags |= save;
> > if (noncontig_write != 0 && bcount > obcount)
> > vfs_bio_bzero_buf(bp, obcount, bcount -
> > obcount);
> > *** This zeros bytes from "obcount" (the offset of the old EOF) to
> > "bcount"
> > (which is the offset of EOF after the write).
>
> I believe that I got it now, the patch in the other message looks
> fine.
> Thank you for the patience.
>
Thanks for the review. It got me to look more closely at the patch and replace
"bcount" with "on", plus other improvements.
Have fun, rick
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