CIFS: Fix read after write for files with read caching

commit 6dfbd84684700cb58b34e8602c01c12f3d2595c8 upstream.

When we have a READ lease for a file and have just issued a write
operation to the server we need to purge the cache and set oplock/lease
level to NONE to avoid reading stale data. Currently we do that
only if a write operation succedeed thus not covering cases when
a request was sent to the server but a negative error code was
returned later for some other reasons (e.g. -EIOCBQUEUED or -EINTR).
Fix this by turning off caching regardless of the error code being
returned.

The patches fixes generic tests 075 and 112 from the xfs-tests.

Cc: <stable@vger.kernel.org>
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 852d7d1dcbbd3772c72258d0c1d20fd27298d534..72d6f4db9bdc6c70403a46a15b75ead0fe6a1aab 100644 (file)
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2889,14 +2889,16 @@ cifs_strict_writev(struct kiocb *iocb, struct iov_iter *from)
         * these pages but not on the region from pos to ppos+len-1.
         */
        written = cifs_user_writev(iocb, from);
-       if (written > 0 && CIFS_CACHE_READ(cinode)) {
+       if (CIFS_CACHE_READ(cinode)) {
                /*
-                * Windows 7 server can delay breaking level2 oplock if a write
-                * request comes - break it on the client to prevent reading
-                * an old data.
+                * We have read level caching and we have just sent a write
+                * request to the server thus making data in the cache stale.
+                * Zap the cache and set oplock/lease level to NONE to avoid
+                * reading stale data from the cache. All subsequent read
+                * operations will read new data from the server.
                 */
                cifs_zap_mapping(inode);
-               cifs_dbg(FYI, "Set no oplock for inode=%p after a write operation\n",
+               cifs_dbg(FYI, "Set Oplock/Lease to NONE for inode=%p after write\n",
                         inode);
                cinode->oplock = 0;
        }