[Devel] [PATCH 04/14] fuse: Prepare to handle multiple pages in writeback

[Miklos Szeredi]

On Mon, Apr 1, 2013 at 12:41 PM, Maxim V. Patlasov
<MPatlasov at parallels.com> wrote:
>
> The .writepages callback will issue writeback requests with more than one
> page aboard. Make existing end/check code be aware of this.
>
> Original patch by: Pavel Emelyanov <xemul at openvz.org>

If this patch was written by Pavel and then modified by you then
please add  a "From:" header at the top of the patch instead.  See
Documentation/SubmittingPatches.

> Signed-off-by: Maxim Patlasov <MPatlasov at parallels.com>
> ---
>  fs/fuse/file.c |   22 +++++++++++++++-------
>  1 files changed, 15 insertions(+), 7 deletions(-)
>
> diff --git a/fs/fuse/file.c b/fs/fuse/file.c
> index 648de34..ee44b24 100644
> --- a/fs/fuse/file.c
> +++ b/fs/fuse/file.c
> @@ -345,7 +345,8 @@ static bool fuse_page_is_writeback(struct inode *inode, pgoff_t index)
>
>                 BUG_ON(req->inode != inode);
>                 curr_index = req->misc.write.in.offset >> PAGE_CACHE_SHIFT;
> -               if (curr_index == index) {
> +               if (curr_index <= index &&
> +                   index < curr_index + req->num_pages) {
>                         found = true;
>                         break;
>                 }
> @@ -1295,7 +1296,10 @@ static ssize_t fuse_direct_write(struct file *file, const char __user *buf,
>
>  static void fuse_writepage_free(struct fuse_conn *fc, struct fuse_req *req)
>  {
> -       __free_page(req->pages[0]);
> +       int i;
> +
> +       for (i = 0; i < req->num_pages; i++)
> +               __free_page(req->pages[i]);
>         fuse_file_put(req->ff, false);
>  }
>
> @@ -1304,10 +1308,13 @@ static void fuse_writepage_finish(struct fuse_conn *fc, struct fuse_req *req)
>         struct inode *inode = req->inode;
>         struct fuse_inode *fi = get_fuse_inode(inode);
>         struct backing_dev_info *bdi = inode->i_mapping->backing_dev_info;
> +       int i;
>
>         list_del(&req->writepages_entry);
> -       dec_bdi_stat(bdi, BDI_WRITEBACK);
> -       dec_zone_page_state(req->pages[0], NR_WRITEBACK_TEMP);
> +       for (i = 0; i < req->num_pages; i++) {
> +               dec_bdi_stat(bdi, BDI_WRITEBACK);
> +               dec_zone_page_state(req->pages[i], NR_WRITEBACK_TEMP);
> +       }
>         bdi_writeout_inc(bdi);
>         wake_up(&fi->page_waitq);
>  }
> @@ -1320,14 +1327,15 @@ __acquires(fc->lock)
>         struct fuse_inode *fi = get_fuse_inode(req->inode);
>         loff_t size = i_size_read(req->inode);
>         struct fuse_write_in *inarg = &req->misc.write.in;
> +       __u64 data_size = req->num_pages * PAGE_CACHE_SIZE;
>
>         if (!fc->connected)
>                 goto out_free;
>
> -       if (inarg->offset + PAGE_CACHE_SIZE <= size) {
> -               inarg->size = PAGE_CACHE_SIZE;
> +       if (inarg->offset + data_size <= size) {
> +               inarg->size = data_size;
>         } else if (inarg->offset < size) {
> -               inarg->size = size & (PAGE_CACHE_SIZE - 1);
> +               inarg->size = size - inarg->offset;
>         } else {
>                 /* Got truncated off completely */
>                 goto out_free;
>