9p: fix readdir corner cases

The patch below also addresses a couple of other corner cases in readdir
seen with a large (e.g. 64k) msize.  I'm not sure what people think of
my co-opting of fid->aux here.  I'd be happy to rework if there's a better
way.

When the size of the user supplied buffer passed to readdir is smaller
than the data returned in one go by the 9P read request, v9fs_dir_readdir()
currently discards extra data so that, on the next call, a 9P read
request will be issued with offset < previous offset + bytes returned,
which voilates the constraint described in paragraph 3 of read(5) description.
This patch preseves the leftover data in fid->aux for use in the next call.

Signed-off-by: Jim Garlick <garlick@llnl.gov>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

1 files changed, 3 insertions, 4 deletions

diff --git a/include/net/9p/client.h b/include/net/9p/client.h
index e26812274b75..fb00b329f0d3 100644
--- a/include/net/9p/client.h
+++ b/include/net/9p/client.h
@@ -159,8 +159,7 @@ struct p9_client {
  * @qid: the &p9_qid server identifier this handle points to
  * @iounit: the server reported maximum transaction size for this file
  * @uid: the numeric uid of the local user who owns this handle
- * @aux: transport specific information (unused?)
- * @rdir_fpos: tracks offset of file position when reading directory contents
+ * @rdir: readdir accounting structure (allocated on demand)
  * @flist: per-client-instance fid tracking
  * @dlist: per-dentry fid tracking
  *
@@ -174,9 +173,9 @@ struct p9_fid {
 	struct p9_qid qid;
 	u32 iounit;
 	uid_t uid;
-	void *aux;
 
-	int rdir_fpos;
+	void *rdir;
+
 	struct list_head flist;
 	struct list_head dlist;	/* list of all fids attached to a dentry */
 };