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Message-ID: <87k3ue3cse.fsf@tucsk.pomaz.szeredi.hu>
Date: Thu, 25 Oct 2012 15:24:17 +0200
From: Miklos Szeredi <miklos@...redi.hu>
To: Maxim Patlasov <mpatlasov@...allels.com>
Cc: fuse-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
devel@...nvz.org
Subject: Re: [PATCH 07/11] fuse: add per-page descriptor <offset, length> to fuse_req (v2)
Maxim Patlasov <mpatlasov@...allels.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 <mpatlasov@...allels.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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