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Subject[PATCH 5.0 054/238] CIFS: Fix read after write for files with read caching
Date
5.0-stable review patch.  If anyone has any objections, please let me know.

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

From: Pavel Shilovsky <piastryyy@gmail.com>

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>

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

--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -3028,14 +3028,16 @@ 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_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;
}

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