On Wed, 21 Aug 2013, Sha Zhengju wrote:
> Following we will begin to add memcg dirty page accounting around
> __set_page_dirty_{buffers,nobuffers} in vfs layer, so we'd better use vfs interface to
> avoid exporting those details to filesystems.
>
> Since vfs set_page_dirty() should be called under page lock, here we don't need elaborate
> codes to handle racy anymore, and two WARN_ON() are added to detect such exceptions.
> Thanks very much for Sage and Yan Zheng's coaching!
>
> I tested it in a two server's ceph environment that one is client and the other is
> mds/osd/mon, and run the following fsx test from xfstests:
>
> ./fsx 1MB -N 50000 -p 10000 -l 1048576
> ./fsx 10MB -N 50000 -p 10000 -l 10485760
> ./fsx 100MB -N 50000 -p 10000 -l 104857600
>
> The fsx does lots of mmap-read/mmap-write/truncate operations and the tests completed
> successfully without triggering any of WARN_ON.
>
> Signed-off-by: Sha Zhengju <handai.szj@xxxxxxxxxx>
Reviewed-by: Sage Weil <sage@xxxxxxxxxxx>
Would you like me to take this through the ceph tree?
Thanks-
sage
> ---
> fs/ceph/addr.c | 42 ++++++++++++++----------------------------
> 1 file changed, 14 insertions(+), 28 deletions(-)
>
> diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
> index afb2fc2..01891f4 100644
> --- a/fs/ceph/addr.c
> +++ b/fs/ceph/addr.c
> @@ -72,13 +72,15 @@ static int ceph_set_page_dirty(struct page *page)
> struct ceph_inode_info *ci;
> int undo = 0;
> struct ceph_snap_context *snapc;
> + int ret;
>
> if (unlikely(!mapping))
> return !TestSetPageDirty(page);
>
> - if (TestSetPageDirty(page)) {
> + if (PageDirty(page)) {
> dout("%p set_page_dirty %p idx %lu -- already dirty\n",
> mapping->host, page, page->index);
> + BUG_ON(!PagePrivate(page));
> return 0;
> }
>
> @@ -107,35 +109,19 @@ static int ceph_set_page_dirty(struct page *page)
> snapc, snapc->seq, snapc->num_snaps);
> spin_unlock(&ci->i_ceph_lock);
>
> - /* now adjust page */
> - spin_lock_irq(&mapping->tree_lock);
> - if (page->mapping) { /* Race with truncate? */
> - WARN_ON_ONCE(!PageUptodate(page));
> - account_page_dirtied(page, page->mapping);
> - radix_tree_tag_set(&mapping->page_tree,
> - page_index(page), PAGECACHE_TAG_DIRTY);
> -
> - /*
> - * Reference snap context in page->private. Also set
> - * PagePrivate so that we get invalidatepage callback.
> - */
> - page->private = (unsigned long)snapc;
> - SetPagePrivate(page);
> - } else {
> - dout("ANON set_page_dirty %p (raced truncate?)\n", page);
> - undo = 1;
> - }
> -
> - spin_unlock_irq(&mapping->tree_lock);
> -
> - if (undo)
> - /* whoops, we failed to dirty the page */
> - ceph_put_wrbuffer_cap_refs(ci, 1, snapc);
> + /*
> + * Reference snap context in page->private. Also set
> + * PagePrivate so that we get invalidatepage callback.
> + */
> + BUG_ON(PagePrivate(page));
> + page->private = (unsigned long)snapc;
> + SetPagePrivate(page);
>
> - __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
> + ret = __set_page_dirty_nobuffers(page);
> + WARN_ON(!PageLocked(page));
> + WARN_ON(!page->mapping);
>
> - BUG_ON(!PageDirty(page));
> - return 1;
> + return ret;
> }
>
> /*
> --
> 1.7.9.5
>
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