[CIFS] Send SMB flush in cifs_fsync
In contrast to the now-obsolete smbfs, cifs does not send SMB_COM_FLUSH
in response to an explicit fsync(2) to guarantee that all volatile data
is written to stable storage on the server side, provided the server
honors the request (which, to my knowledge, is true for Windows and
Samba with 'strict sync' enabled).
This patch modifies the cifs_fsync implementation to restore the
fsync-behavior of smbfs by triggering SMB_COM_FLUSH after sending
outstanding data on the client side to the server.
Signed-off-by: Horst Reiterer <horst.reiterer@gmail.com>
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/cifs/CHANGES b/fs/cifs/CHANGES
index 851388f..d43e0fe 100644
--- a/fs/cifs/CHANGES
+++ b/fs/cifs/CHANGES
@@ -6,7 +6,9 @@
are authenticated as guest, as reconnections, invalidating the earlier
user's smb session. This fix allows cifs to mount multiple times to the
same server with different userids without risking invalidating earlier
-established security contexts.
+established security contexts. fsync now sends SMB Flush operation
+to better ensure that we wait for server to write all of the data to
+server disk (not just write it over the network).
Version 1.56
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