[PATCH 3.13 137/187] CIFS: Fix async reading on reconnects

Kamal Mostafa
2014-09-15T23:09:32Z

From: Pavel Shilovsky <pshilovsky@samba.org>

commit 038bc961c31b070269ecd07349a7ee2e839d4fec upstream.

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>
Signed-off-by: Pavel Shilovsky <pshilovsky@samba.org>
Signed-off-by: Steve French <smfrench@gmail.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
fs/cifs/file.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 4911dc8..dd4aaca 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2847,7 +2847,7 @@ 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;
}

static ssize_t
@@ -3270,7 +3270,7 @@ 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,
--
1.9.1