The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

Possible dependencies:

bb44c31cdcac ("cifs: destage dirty pages before re-reading them for cache=none") 6e6e2b86c29c ("CIFS: Add support for direct I/O read")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From bb44c31cdcac107344dd2fcc3bd0504a53575c51 Mon Sep 17 00:00:00 2001 From: Ronnie Sahlberg lsahlber@redhat.com Date: Tue, 20 Sep 2022 14:32:02 +1000 Subject: [PATCH] cifs: destage dirty pages before re-reading them for cache=none

This is the opposite case of kernel bugzilla 216301. If we mmap a file using cache=none and then proceed to update the mmapped area these updates are not reflected in a later pread() of that part of the file. To fix this we must first destage any dirty pages in the range before we allow the pread() to proceed.

Cc: stable@vger.kernel.org Reviewed-by: Paulo Alcantara (SUSE) pc@cjr.nz Reviewed-by: Enzo Matsumiya ematsumiya@suse.de Signed-off-by: Ronnie Sahlberg lsahlber@redhat.com Signed-off-by: Steve French stfrench@microsoft.com

diff --git a/fs/cifs/file.c b/fs/cifs/file.c index 6f38b134a346..7d756721e1a6 100644 --- a/fs/cifs/file.c +++ b/fs/cifs/file.c @@ -4271,6 +4271,15 @@ static ssize_t __cifs_readv( len = ctx->len; }

+ if (direct) { + rc = filemap_write_and_wait_range(file->f_inode->i_mapping, + offset, offset + len - 1); + if (rc) { + kref_put(&ctx->refcount, cifs_aio_ctx_release); + return -EAGAIN; + } + } + /* grab a lock here due to read response handlers can access ctx */ mutex_lock(&ctx->aio_mutex);