Maxim Patlasov <mpatla...@parallels.com> writes:

> The ability to save page pointers along with lengths and offsets in fuse_req
> will be useful to cover several iovec-s with a single fuse_req.
>
> Per-request page_offset is removed because anybody who need it can use
> req->page_descs[0].offset instead.
>
> Changed in v2:
>  - replaced structure page_desc with fuse_page_desc
>
> Signed-off-by: Maxim Patlasov <mpatla...@parallels.com>
> ---
>  fs/fuse/dev.c    |   26 +++++++++++++++++++-------
>  fs/fuse/file.c   |   10 +++++-----
>  fs/fuse/fuse_i.h |   15 ++++++++++++---
>  3 files changed, 36 insertions(+), 15 deletions(-)
>
> diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
> index b241a7d..72ad962 100644
> --- a/fs/fuse/dev.c
> +++ b/fs/fuse/dev.c
> @@ -35,14 +35,17 @@ static struct fuse_conn *fuse_get_conn(struct file *file)
>  }
>  
>  static void fuse_request_init(struct fuse_req *req, struct page **pages,
> +                           struct fuse_page_desc *page_descs,
>                             unsigned npages)
>  {
>       memset(req, 0, sizeof(*req));
> +     memset(page_descs, 0, sizeof(*page_descs) * npages);

Makes me wonder:  why aren't we zeroing out the page array too?

>       INIT_LIST_HEAD(&req->list);
>       INIT_LIST_HEAD(&req->intr_entry);
>       init_waitqueue_head(&req->waitq);
>       atomic_set(&req->count, 1);
>       req->pages = pages;
> +     req->page_descs = page_descs;
>       req->max_pages = npages;
>  }
>  
> @@ -51,18 +54,25 @@ static struct fuse_req *__fuse_request_alloc(int npages, 
> gfp_t flags)
>       struct fuse_req *req = kmem_cache_alloc(fuse_req_cachep, flags);
>       if (req) {
>               struct page **pages;
> +             struct fuse_page_desc *page_descs;
>  
> -             if (npages <= FUSE_REQ_INLINE_PAGES)
> +             if (npages <= FUSE_REQ_INLINE_PAGES) {
>                       pages = req->inline_pages;
> -             else
> +                     page_descs = req->inline_page_descs;
> +             } else {
>                       pages = kmalloc(sizeof(struct page *) * npages, flags);
> +                     page_descs = kmalloc(sizeof(struct fuse_page_desc) *
> +                                          npages, flags);
> +             }
>  
> -             if (!pages) {
> +             if (!pages || !page_descs) {
> +                     kfree(pages);
> +                     kfree(page_descs);
>                       kmem_cache_free(fuse_req_cachep, req);
>                       return NULL;
>               }
>  
> -             fuse_request_init(req, pages, npages);
> +             fuse_request_init(req, pages, page_descs, npages);
>       }
>       return req;
>  }
> @@ -82,6 +92,8 @@ void fuse_request_free(struct fuse_req *req)
>  {
>       if (req->pages != req->inline_pages)
>               kfree(req->pages);
> +     if (req->page_descs != req->inline_page_descs)
> +             kfree(req->page_descs);

You allocate them together, you can free them together.  Just add a
BUG_ON() if you feel paranoid.

>       kmem_cache_free(fuse_req_cachep, req);
>  }
>  
> @@ -186,7 +198,7 @@ static void put_reserved_req(struct fuse_conn *fc, struct 
> fuse_req *req)
>       struct fuse_file *ff = file->private_data;
>  
>       spin_lock(&fc->lock);
> -     fuse_request_init(req, req->pages, req->max_pages);
> +     fuse_request_init(req, req->pages, req->page_descs, req->max_pages);
>       BUG_ON(ff->reserved_req);
>       ff->reserved_req = req;
>       wake_up_all(&fc->reserved_req_waitq);
> @@ -877,7 +889,7 @@ static int fuse_copy_pages(struct fuse_copy_state *cs, 
> unsigned nbytes,
>  {
>       unsigned i;
>       struct fuse_req *req = cs->req;
> -     unsigned offset = req->page_offset;
> +     unsigned offset = req->page_descs[0].offset;
>       unsigned count = min(nbytes, (unsigned) PAGE_SIZE - offset);
>  
>       for (i = 0; i < req->num_pages && (nbytes || zeroing); i++) {
> @@ -1585,7 +1597,7 @@ static int fuse_retrieve(struct fuse_conn *fc, struct 
> inode *inode,
>       req->in.h.nodeid = outarg->nodeid;
>       req->in.numargs = 2;
>       req->in.argpages = 1;
> -     req->page_offset = offset;
> +     req->page_descs[0].offset = offset;
>       req->end = fuse_retrieve_end;
>  
>       index = outarg->offset >> PAGE_CACHE_SHIFT;
> diff --git a/fs/fuse/file.c b/fs/fuse/file.c
> index 08899a6..b68cf3b 100644
> --- a/fs/fuse/file.c
> +++ b/fs/fuse/file.c
> @@ -798,7 +798,7 @@ static size_t fuse_send_write_pages(struct fuse_req *req, 
> struct file *file,
>  
>       res = fuse_send_write(req, file, pos, count, NULL);
>  
> -     offset = req->page_offset;
> +     offset = req->page_descs[0].offset;
>       count = res;
>       for (i = 0; i < req->num_pages; i++) {
>               struct page *page = req->pages[i];
> @@ -829,7 +829,7 @@ static ssize_t fuse_fill_write_pages(struct fuse_req *req,
>       int err;
>  
>       req->in.argpages = 1;
> -     req->page_offset = offset;
> +     req->page_descs[0].offset = offset;
>  
>       do {
>               size_t tmp;
> @@ -1070,14 +1070,14 @@ static int fuse_get_user_pages(struct fuse_req *req, 
> const char __user *buf,
>               return npages;
>  
>       req->num_pages = npages;
> -     req->page_offset = offset;
> +     req->page_descs[0].offset = offset;
>  
>       if (write)
>               req->in.argpages = 1;
>       else
>               req->out.argpages = 1;
>  
> -     nbytes = (req->num_pages << PAGE_SHIFT) - req->page_offset;
> +     nbytes = (req->num_pages << PAGE_SHIFT) - req->page_descs[0].offset;
>       *nbytesp = min(*nbytesp, nbytes);
>  
>       return 0;
> @@ -1314,7 +1314,7 @@ static int fuse_writepage_locked(struct page *page)
>       req->in.argpages = 1;
>       req->num_pages = 1;
>       req->pages[0] = tmp_page;
> -     req->page_offset = 0;
> +     req->page_descs[0].offset = 0;
>       req->end = fuse_writepage_end;
>       req->inode = inode;
>  
> diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
> index fd69d62..c07e454 100644
> --- a/fs/fuse/fuse_i.h
> +++ b/fs/fuse/fuse_i.h
> @@ -203,6 +203,12 @@ struct fuse_out {
>       struct fuse_arg args[3];
>  };
>  
> +/** FUSE page descriptor */
> +struct fuse_page_desc {
> +     unsigned int length;
> +     unsigned int offset;
> +};
> +
>  /** The request state */
>  enum fuse_req_state {
>       FUSE_REQ_INIT = 0,
> @@ -296,18 +302,21 @@ struct fuse_req {
>       /** page vector */
>       struct page **pages;
>  
> +     /** page-descriptor vector */
> +     struct fuse_page_desc *page_descs;
> +
>       /** size of the 'pages' array */
>       unsigned max_pages;
>  
>       /** inline page vector */
>       struct page *inline_pages[FUSE_REQ_INLINE_PAGES];
>  
> +     /** inline page-descriptor vector */
> +     struct fuse_page_desc inline_page_descs[FUSE_REQ_INLINE_PAGES];
> +
>       /** number of pages in vector */
>       unsigned num_pages;
>  
> -     /** offset of data on first page */
> -     unsigned page_offset;
> -
>       /** File used in the request (or NULL) */
>       struct fuse_file *ff;
>  

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