From: Matthew Wilcox <willy@infradead.org>
To: Dave Chinner <david@fromorbit.com>
Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, linux-btrfs@vger.kernel.org
Subject: Re: [PATCH 06/12] btrfs: Convert from readpages to readahead
Date: Thu, 30 Jan 2020 00:09:39 -0800 [thread overview]
Message-ID: <20200130080939.GL6615@bombadil.infradead.org> (raw)
In-Reply-To: <20200129004609.GI18610@dread.disaster.area>
On Wed, Jan 29, 2020 at 11:46:09AM +1100, Dave Chinner wrote:
> On Fri, Jan 24, 2020 at 05:35:47PM -0800, Matthew Wilcox wrote:
> > From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
> >
> > Use the new readahead operation in btrfs
> >
> > Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> > Cc: linux-btrfs@vger.kernel.org
> > ---
> > fs/btrfs/extent_io.c | 15 ++++-----------
> > fs/btrfs/extent_io.h | 2 +-
> > fs/btrfs/inode.c | 18 +++++++++---------
> > 3 files changed, 14 insertions(+), 21 deletions(-)
> >
> > diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
> > index 2f4802f405a2..b1e2acbec165 100644
> > --- a/fs/btrfs/extent_io.c
> > +++ b/fs/btrfs/extent_io.c
> > @@ -4283,7 +4283,7 @@ int extent_writepages(struct address_space *mapping,
> > return ret;
> > }
> >
> > -int extent_readpages(struct address_space *mapping, struct list_head *pages,
> > +unsigned extent_readahead(struct address_space *mapping, pgoff_t start,
> > unsigned nr_pages)
> > {
> > struct bio *bio = NULL;
> > @@ -4294,20 +4294,13 @@ int extent_readpages(struct address_space *mapping, struct list_head *pages,
> > int nr = 0;
> > u64 prev_em_start = (u64)-1;
> >
> > - while (!list_empty(pages)) {
> > + while (nr_pages) {
> > u64 contig_end = 0;
> >
> > - for (nr = 0; nr < ARRAY_SIZE(pagepool) && !list_empty(pages);) {
> > - struct page *page = lru_to_page(pages);
> > + for (nr = 0; nr < ARRAY_SIZE(pagepool) && nr_pages--;) {
>
> What is stopping nr_pages from going negative here, and then looping
> forever on the outer nr_pages loop? Perhaps "while(nr_pages > 0) {"
> would be better there?
Ugh, nr_pages is unsigned, so that's no good. Maybe make this a more
conventional loop ...
while (nr_pages) {
u64 contig_end = 0;
for (nr = 0; nr < ARRAY_SIZE(pagepool); nr++) {
struct page *page = readahead_page(mapping, start++);
prefetchw(&page->flags);
pagepool[nr] = page;
contig_end = page_offset(page) + PAGE_SIZE - 1;
if (--nr_pages == 0)
break;
}
next prev parent reply other threads:[~2020-01-30 8:09 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-25 1:35 [PATCH 00/12] Change readahead API Matthew Wilcox
2020-01-25 1:35 ` [PATCH 01/12] mm: Fix the return type of __do_page_cache_readahead Matthew Wilcox
2020-01-25 1:35 ` [PATCH 02/12] readahead: Ignore return value of ->readpages Matthew Wilcox
2020-01-25 1:35 ` [PATCH 03/12] readahead: Put pages in cache earlier Matthew Wilcox
2020-01-25 19:44 ` Matthew Wilcox
2020-01-25 1:35 ` [PATCH 04/12] mm: Add readahead address space operation Matthew Wilcox
2020-01-25 3:57 ` Randy Dunlap
2020-02-01 0:25 ` Matthew Wilcox
2020-01-29 0:24 ` Dave Chinner
2020-01-30 8:00 ` Matthew Wilcox
2020-01-25 1:35 ` [PATCH 05/12] fs: Convert mpage_readpages to mpage_readahead Matthew Wilcox
2020-01-25 1:35 ` [PATCH 06/12] btrfs: Convert from readpages to readahead Matthew Wilcox
2020-01-29 0:46 ` Dave Chinner
2020-01-30 8:09 ` Matthew Wilcox [this message]
2020-01-31 2:17 ` Dave Chinner
2020-01-25 1:35 ` [PATCH 07/12] erofs: Convert uncompressed files " Matthew Wilcox
2020-01-25 1:53 ` Gao Xiang
2020-01-25 19:09 ` Matthew Wilcox
2020-01-29 0:57 ` Dave Chinner
2020-01-30 8:10 ` Matthew Wilcox
2020-01-25 1:35 ` [PATCH 08/12] erofs: Convert compressed " Matthew Wilcox
2020-01-25 1:35 ` [PATCH 09/12] ext4: Convert " Matthew Wilcox
2020-01-25 1:35 ` [PATCH 10/12] f2fs: " Matthew Wilcox
2020-01-25 1:35 ` [PATCH 11/12] fuse: " Matthew Wilcox
2020-01-29 1:08 ` Dave Chinner
2020-01-30 21:35 ` Matthew Wilcox
2020-01-31 2:19 ` Dave Chinner
2020-01-29 10:50 ` Miklos Szeredi
2020-01-30 7:26 ` Matthew Wilcox
2020-01-25 1:35 ` [PATCH 12/12] iomap: " Matthew Wilcox
2020-01-29 1:38 ` Dave Chinner
2020-01-31 9:44 ` Matthew Wilcox
2020-02-13 4:38 ` [PATCH 00/12] Change readahead API Andrew Morton
2020-02-13 13:43 ` Matthew Wilcox
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