[PATCH] fuse: use asynchronous READ requests for readpages

This patch changes fuse_readpages() to send READ requests asynchronously.

This makes it possible for userspace filesystems to utilize the kernel
readahead logic instead of having to implement their own (resulting in double
caching).

Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 4a0b0f9..a7ef5e7 100644 (file)
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -265,7 +265,7 @@ void fuse_read_fill(struct fuse_req *req, struct file *file,
        req->file = file;
        req->in.numargs = 1;
        req->in.args[0].size = sizeof(struct fuse_read_in);
-       req->in.args[0].value = &inarg;
+       req->in.args[0].value = inarg;
        req->out.argpages = 1;
        req->out.argvar = 1;
        req->out.numargs = 1;
@@ -311,21 +311,33 @@ static int fuse_readpage(struct file *file, struct page *page)
        return err;
 }
 
-static int fuse_send_readpages(struct fuse_req *req, struct file *file,
-                              struct inode *inode)
+static void fuse_readpages_end(struct fuse_conn *fc, struct fuse_req *req)
 {
-       loff_t pos = page_offset(req->pages[0]);
-       size_t count = req->num_pages << PAGE_CACHE_SHIFT;
-       unsigned i;
-       req->out.page_zeroing = 1;
-       fuse_send_read(req, file, inode, pos, count);
+       int i;
+
+       fuse_invalidate_attr(req->pages[0]->mapping->host); /* atime changed */
+
        for (i = 0; i < req->num_pages; i++) {
                struct page *page = req->pages[i];
                if (!req->out.h.error)
                        SetPageUptodate(page);
+               else
+                       SetPageError(page);
                unlock_page(page);
        }
-       return req->out.h.error;
+       fuse_put_request(fc, req);
+}
+
+static void fuse_send_readpages(struct fuse_req *req, struct file *file,
+                               struct inode *inode)
+{
+       struct fuse_conn *fc = get_fuse_conn(inode);
+       loff_t pos = page_offset(req->pages[0]);
+       size_t count = req->num_pages << PAGE_CACHE_SHIFT;
+       req->out.page_zeroing = 1;
+       req->end = fuse_readpages_end;
+       fuse_read_fill(req, file, inode, pos, count, FUSE_READ);
+       request_send_background(fc, req);
 }
 
 struct fuse_readpages_data {
@@ -345,12 +357,12 @@ static int fuse_readpages_fill(void *_data, struct page *page)
            (req->num_pages == FUSE_MAX_PAGES_PER_REQ ||
             (req->num_pages + 1) * PAGE_CACHE_SIZE > fc->max_read ||
             req->pages[req->num_pages - 1]->index + 1 != page->index)) {
-               int err = fuse_send_readpages(req, data->file, inode);
-               if (err) {
+               fuse_send_readpages(req, data->file, inode);
+               data->req = req = fuse_get_request(fc);
+               if (!req) {
                        unlock_page(page);
-                       return err;
+                       return -EINTR;
                }
-               fuse_reset_request(req);
        }
        req->pages[req->num_pages] = page;
        req->num_pages ++;
@@ -375,10 +387,8 @@ static int fuse_readpages(struct file *file, struct address_space *mapping,
                return -EINTR;
 
        err = read_cache_pages(mapping, pages, fuse_readpages_fill, &data);
-       if (!err && data.req->num_pages)
-               err = fuse_send_readpages(data.req, file, inode);
-       fuse_put_request(fc, data.req);
-       fuse_invalidate_attr(inode); /* atime changed */
+       if (!err)
+               fuse_send_readpages(data.req, file, inode);
        return err;
 }