fuse: add per-page descriptor <offset, length> to fuse_req

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.

Signed-off-by: Maxim Patlasov <mpatlasov@parallels.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

3 files changed, 37 insertions, 16 deletions

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 28d9792de4a2..db4af8f3886a 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -35,15 +35,18 @@ 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(pages, 0, sizeof(*pages) * npages);
+        memset(page_descs, 0, sizeof(*page_descs) * npages);
         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;
 }
 
@@ -52,18 +55,25 @@ static struct fuse_req *__fuse_request_alloc(unsigned 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;
 }
@@ -81,8 +91,10 @@ struct fuse_req *fuse_request_alloc_nofs(unsigned npages)
 
 void fuse_request_free(struct fuse_req *req)
 {
-        if (req->pages != req->inline_pages)
+        if (req->pages != req->inline_pages) {
                 kfree(req->pages);
+                kfree(req->page_descs);
+        }
         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);
@@ -891,7 +903,7 @@ 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++) {
@@ -1599,7 +1611,7 @@ 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 fdb5b33198aa..2b6f08ac62c3 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 5b21e6ab9e75..70cef60afe0e 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;