On Mon, Jun 14, 2010 at 04:17:36AM -0400, Christoph Hellwig wrote:
> On Tue, Jun 08, 2010 at 10:24:04AM -0400, Josef Bacik wrote:
> > Since BTRFS can fallback on buffered reads after having done some direct
> > reads,
> > we need to make sure to invalidate any pages that we may have read by doing
> > buffered IO. This shouldn't have shown up as a visible user problem, it's
> > just
> > for correctness sake. Thanks,
>
> Everything else in direct I/O land uses invalidate_inode_pages2(_range),
> why not this one?
>
In __generic_file_aio_write if we fall back on buffered writes we call
invalidate_mapping_pages to invalidate the buffered range, so I just did that
here, is that acceptable?
> > loff_t *ppos = &iocb->ki_pos;
> > + bool invalidate = false;
> >
> > count = 0;
> > retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
> > @@ -1291,7 +1292,8 @@ generic_file_aio_read(struct kiocb *iocb, const
> > struct iovec *iov,
> > iov, pos, nr_segs);
> > }
> > if (retval > 0) {
> > - *ppos = pos + retval;
> > + pos += retval;
> > + *ppos = pos;
> > count -= retval;
> > }
> >
> > @@ -1307,6 +1309,7 @@ generic_file_aio_read(struct kiocb *iocb, const
> > struct iovec *iov,
> > file_accessed(filp);
> > goto out;
> > }
> > + invalidate = true;
> > }
> > }
> >
> > @@ -1343,6 +1346,10 @@ generic_file_aio_read(struct kiocb *iocb, const
> > struct iovec *iov,
> > if (desc.count > 0)
> > break;
> > }
> > + if (invalidate && retval > 0)
> > + invalidate_mapping_pages(filp->f_mapping,
> > + pos >> PAGE_CACHE_SHIFT,
> > + (*ppos - 1) >> PAGE_CACHE_SHIFT);
>
> A little comment here would be surely useful. Telling that we want to
> get rid of the pages again if we were falling through from an attempted
> direct I/O read.
>
Will do. I'll send an updated patch when you answer my above question. Thanks
for the review.
Josef
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