On Wed, 2016-08-31 at 12:59 +1000, NeilBrown wrote:
> If O_DIRECT writes are racing with buffered writes, then
> the call to invalidate_inode_pages2_range() can call ceph_releasepage()
> on dirty pages.
>
> Most filesystems hold inode_lock() across O_DIRECT writes so they do not
> suffer this race, but cephfs deliberately drops the lock, and opens a window
> for the race.
>
> This race can be triggered with the generic/036 test from the xfstests
> test suite. It doesn't happen every time, but it does happen often.
>
> As the possibilty is expected, remove the warning, and instead include
> the PageDirty() status in the debug message.
>
> > Signed-off-by: NeilBrown <neilb@xxxxxxxx>
> ---
> fs/ceph/addr.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
> index d5b6f959a3c3..f657da7d12ff 100644
> --- a/fs/ceph/addr.c
> +++ b/fs/ceph/addr.c
> @@ -175,9 +175,8 @@ static void ceph_invalidatepage(struct page *page, unsigned int offset,
>
> static int ceph_releasepage(struct page *page, gfp_t g)
> {
> > - dout("%p releasepage %p idx %lu\n", page->mapping->host,
> > - page, page->index);
> > - WARN_ON(PageDirty(page));
> > + dout("%p releasepage %p idx %lu (%sdirty)\n", page->mapping->host,
> > + page, page->index, PageDirty(page) ? "" : "not ");
>
> > /* Can we release the page from the cache? */
> > if (!ceph_release_fscache_page(page, g))
Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
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