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

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 <[email protected]>.

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 '<[email protected]>' --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 <[email protected]>
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.

index 5062474991cf..f29555f3c7d0 100644
@@ -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)) {