[PATCH 3.18 109/134] CIFS: Fix read after write for files with read caching

From: Greg Kroah-Hartman
Date: Fri Mar 22 2019 - 07:25:14 EST

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


From: Pavel Shilovsky <piastryyy@xxxxxxxxx>

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

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

Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Pavel Shilovsky <pshilov@xxxxxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
Reviewed-by: Ronnie Sahlberg <lsahlber@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

fs/cifs/file.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)

--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2772,14 +2772,16 @@ cifs_strict_writev(struct kiocb *iocb, s
* 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_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",
cinode->oplock = 0;