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, 2 insertions, 3 deletions

diff --git a/net/9p/client.c b/net/9p/client.c
index 5bf5f227dbe0..8af95b2dddd6 100644
--- a/net/9p/client.c
+++ b/net/9p/client.c
@@ -582,11 +582,9 @@ static struct p9_fid *p9_fid_create(struct p9_client *clnt)
 
         memset(&fid->qid, 0, sizeof(struct p9_qid));
         fid->mode = -1;
-        fid->rdir_fpos = 0;
         fid->uid = current_fsuid();
         fid->clnt = clnt;
-        fid->aux = NULL;
-
+        fid->rdir = NULL;
         spin_lock_irqsave(&clnt->lock, flags);
         list_add(&fid->flist, &clnt->fidlist);
         spin_unlock_irqrestore(&clnt->lock, flags);
@@ -609,6 +607,7 @@ static void p9_fid_destroy(struct p9_fid *fid)
         spin_lock_irqsave(&clnt->lock, flags);
         list_del(&fid->flist);
         spin_unlock_irqrestore(&clnt->lock, flags);
+        kfree(fid->rdir);
         kfree(fid);
 }