fuse: Prepare to handle short reads

A helper which gets called when read reports less bytes than was requested.
See patch "trust kernel i_size only" for details.

Signed-off-by: Maxim Patlasov <MPatlasov@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

1 files changed, 13 insertions, 8 deletions

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 2489aca4d1a6..592d7b48e421 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -671,6 +671,15 @@ static void fuse_read_update_size(struct inode *inode, loff_t size,
         spin_unlock(&fc->lock);
 }
 
+static void fuse_short_read(struct fuse_req *req, struct inode *inode,
+                            u64 attr_ver)
+{
+        size_t num_read = req->out.args[0].size;
+
+        loff_t pos = page_offset(req->pages[0]) + num_read;
+        fuse_read_update_size(inode, pos, attr_ver);
+}
+
 static int fuse_readpage(struct file *file, struct page *page)
 {
         struct fuse_io_priv io = { .async = 0, .file = file };
@@ -708,18 +717,18 @@ static int fuse_readpage(struct file *file, struct page *page)
         req->page_descs[0].length = count;
         num_read = fuse_send_read(req, &io, pos, count, NULL);
         err = req->out.h.error;
-        fuse_put_request(fc, req);
 
         if (!err) {
                 /*
                  * Short read means EOF.  If file size is larger, truncate it
                  */
                 if (num_read < count)
-                        fuse_read_update_size(inode, pos + num_read, attr_ver);
+                        fuse_short_read(req, inode, attr_ver);
 
                 SetPageUptodate(page);
         }
 
+        fuse_put_request(fc, req);
         fuse_invalidate_atime(inode);
  out:
         unlock_page(page);
@@ -742,13 +751,9 @@ static void fuse_readpages_end(struct fuse_conn *fc, struct fuse_req *req)
                 /*
                  * Short read means EOF. If file size is larger, truncate it
                  */
-                if (!req->out.h.error && num_read < count) {
-                        loff_t pos;
+                if (!req->out.h.error && num_read < count)
+                        fuse_short_read(req, inode, req->misc.read.attr_ver);
 
-                        pos = page_offset(req->pages[0]) + num_read;
-                        fuse_read_update_size(inode, pos,
-                                              req->misc.read.attr_ver);
-                }
                 fuse_invalidate_atime(inode);
         }