[PATCH 3.14 099/114] CIFS: Fix async reading on reconnects

[Greg Kroah-Hartman]

3.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Pavel Shilovsky <pshilovsky@xxxxxxxxx>

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@xxxxxxxxx>
Signed-off-by: Pavel Shilovsky <pshilovsky@xxxxxxxxx>
Signed-off-by: Steve French <smfrench@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 fs/cifs/file.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2844,7 +2844,7 @@ cifs_uncached_read_into_pages(struct TCP
 		total_read += result;
 	}
 
-	return total_read > 0 ? total_read : result;
+	return total_read > 0 && result != -EAGAIN ? total_read : result;
 }
 
 static ssize_t
@@ -3267,7 +3267,7 @@ cifs_readpages_read_into_pages(struct TC
 		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,


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