On Fri, Jun 8, 2012 at 8:13 PM, Boaz Harrosh <bharrosh@xxxxxxxxxxx> wrote:
>
> It is very common for the end of the file to be unaligned on
> stripe size. But since we know it's beyond file's end then
> the XOR should be preformed with all zeros.
>
> Old code used to just read zeros out of the OSD devices, which is a great
> waist. But what scares me more about this situation is that, we now have
> pages attached to the file's mapping that are beyond i_size. I don't
> like the kind of bugs this calls for.
>
> Fix both birds, by returning a global zero_page, if offset is beyond
> i_size.
>
> TODO:
> Change the API to ->__r4w_get_page() so a NULL can be
> returned without being considered as error, since XOR API
> treats NULL entries as zero_pages.
>
> [Bug since 3.2. Should apply the same way to all Kernels since]
> CC: Stable Tree <stable@xxxxxxxxxx>
> Signed-off-by: Boaz Harrosh <bharrosh@xxxxxxxxxxx>
> ---
> fs/nfs/objlayout/objio_osd.c | 24 +++++++++++++++++++++---
> 1 file changed, 21 insertions(+), 3 deletions(-)
>
> diff --git a/fs/nfs/objlayout/objio_osd.c b/fs/nfs/objlayout/objio_osd.c
> index b47277b..0e7c833 100644
> --- a/fs/nfs/objlayout/objio_osd.c
> +++ b/fs/nfs/objlayout/objio_osd.c
> @@ -480,14 +480,28 @@ static void _write_done(struct ore_io_state *ios, void *private)
> objlayout_write_done(&objios->oir, status, objios->sync);
> }
>
> +static struct page *g_zero_page;
> +
Since you don't attach g_zero_page to any file's address space, I
think that you can replace it with ZERO_PAGE(0), no?
Cheers,
Tao
> static struct page *__r4w_get_page(void *priv, u64 offset, bool *uptodate)
> {
> struct objio_state *objios = priv;
> struct nfs_write_data *wdata = objios->oir.rpcdata;
> struct address_space *mapping = wdata->header->inode->i_mapping;
> pgoff_t index = offset / PAGE_SIZE;
> - struct page *page = find_get_page(mapping, index);
> + struct page *page;
> + loff_t i_size = i_size_read(wdata->header->inode);
> +
> + if (offset >= i_size) {
> + if (!g_zero_page) {
> + g_zero_page = alloc_page(GFP_NOFS);
> + clear_highpage(g_zero_page);
> + }
> + *uptodate = true;
> + dprintk("%s: g_zero_page index=0x%lx\n", __func__, index);
> + return g_zero_page;
> + }
>
> + page = find_get_page(mapping, index);
> if (!page) {
> page = find_or_create_page(mapping, index, GFP_NOFS);
> if (unlikely(!page)) {
> @@ -507,8 +521,10 @@ static struct page *__r4w_get_page(void *priv, u64 offset, bool *uptodate)
>
> static void __r4w_put_page(void *priv, struct page *page)
> {
> - dprintk("%s: index=0x%lx\n", __func__, page->index);
> - page_cache_release(page);
> + dprintk("%s: index=0x%lx\n", __func__,
> + (page == g_zero_page) ? -1UL : page->index);
> + if (g_zero_page != page)
> + page_cache_release(page);
> return;
> }
>
> @@ -615,6 +631,8 @@ static bool objio_pg_test(struct nfs_pageio_descriptor *pgio,
> static void __exit
> objlayout_exit(void)
> {
> + if (g_zero_page)
> + __free_page(g_zero_page);
> pnfs_unregister_layoutdriver(&objlayout_type);
> printk(KERN_INFO "NFS: %s: Unregistered OSD pNFS Layout Driver\n",
> __func__);
> --
> 1.7.10.2.677.gb6bc67f
>
>
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