[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>

1 files changed, 27 insertions, 17 deletions

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 4a0b0f9a2179..a7ef5e716f3c 100644
--- 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;
 }