CIFS: Fix async reading on reconnects

If we get into read_into_pages() from cifs_readv_receive() and then
loose a network, we issue cifs_reconnect that moves all mids to
a private list and issue their callbacks. The callback of the async
read request sets a mid to retry, frees it and wakes up a process
that waits on the rdata completion.

After the connection is established we return from read_into_pages()
with a short read, use the mid that was freed before and try to read
the remaining data from the a newly created socket. Both actions are
not what we want to do. In reconnect cases (-EAGAIN) we should not
mask off the error with a short read but should return the error
code instead.

Acked-by: Jeff Layton <jlayton@samba.org>
Cc: stable@vger.kernel.org
Signed-off-by: Pavel Shilovsky <pshilovsky@samba.org>
Signed-off-by: Steve French <smfrench@gmail.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index e90a1e9aa627..6b6df30cfd89 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2823,7 +2823,7 @@ cifs_uncached_read_into_pages(struct TCP_Server_Info *server,
                 total_read += result;
         }
 
-        return total_read > 0 ? total_read : result;
+        return total_read > 0 && result != -EAGAIN ? total_read : result;
 }
 
 ssize_t cifs_user_readv(struct kiocb *iocb, struct iov_iter *to)
@@ -3231,7 +3231,7 @@ cifs_readpages_read_into_pages(struct TCP_Server_Info *server,
                 total_read += result;
         }
 
-        return total_read > 0 ? total_read : result;
+        return total_read > 0 && result != -EAGAIN ? total_read : result;
 }
 
 static int cifs_readpages(struct file *file, struct address_space *mapping,