FAILED: patch "[PATCH] smb: client: require stable pages for signed connections" failed to apply to 6.18-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 6.18-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>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.18.y
git checkout FETCH_HEAD
git cherry-pick -x 53c5c2c1095eb21e214811fec16cd75f89d72ee2
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026100543-helper-putt-aa16@gregkh' --subject-prefix 'PATCH 6.18.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

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

From 53c5c2c1095eb21e214811fec16cd75f89d72ee2 Mon Sep 17 00:00:00 2001
From: Paulo Alcantara <pc@manguebit.org>
Date: Mon, 28 Sep 2026 10:23:00 -0300
Subject: [PATCH] smb: client: require stable pages for signed connections

When signing, cifs computes the SMB signature over the pagecache folios
in place and then hands those same folios to the socket.  If a buffered
write mutates a folio while a write subrequest is still in flight, the
signature no longer matches the data that follows it, the server rejects
the write with STATUS_ACCESS_DENIED (-EACCES), and the error is latched
in the mapping, so the next fsync()/fallocate() returns -EIO.

Mark the mapping for stable writes so netfs_perform_write() waits for
writeback to complete before modifying an in-flight folio.  This is
only needed when the connection is signed.

Fixes: 3ee1a1fc3981 ("cifs: Cut over to using netfslib")
Reviewed-by: David Howells <dhowells@redhat.com>
Reviewed-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Paulo Alcantara <pc@manguebit.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ronnie Sahlberg <ronniesahlberg@gmail.com>
Cc: Shyam Prasad N <sprasad@microsoft.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Bharath SM <bharathsm@microsoft.com>
Cc: stable@vger.kernel.org

diff --git a/fs/smb/client/inode.c b/fs/smb/client/inode.c
index 5062474991cf..f29555f3c7d0 100644
--- a/fs/smb/client/inode.c
+++ b/fs/smb/client/inode.c
@@ -88,6 +88,8 @@ static void cifs_set_ops(struct inode *inode)
 		else
 			inode->i_data.a_ops = &cifs_addr_ops;
 		mapping_set_large_folios(inode->i_mapping);
+		if (tcon->ses->server->sign)
+			mapping_set_stable_writes(inode->i_mapping);
 		break;
 	case S_IFDIR:
 		if (IS_AUTOMOUNT(inode)) {