linux-kernel - [RFC PATCH v5 05/10] ovl: mark overlayfs' inode dirty on shared mmap

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Date:   Thu, 23 Sep 2021 21:08:09 +0800
From:   Chengguang Xu <cgxu519@...ernel.net>
To:     miklos@...redi.hu, jack@...e.cz, amir73il@...il.com
Cc:     linux-fsdevel@...r.kernel.org, linux-unionfs@...r.kernel.org,
        linux-kernel@...r.kernel.org, Chengguang Xu <cgxu519@...ernel.net>
Subject: [RFC PATCH v5 05/10] ovl: mark overlayfs' inode dirty on shared mmap

Overlayfs cannot be notified when mmapped area gets dirty,
so we need to proactively mark inode dirty in ->mmap operation.

Signed-off-by: Chengguang Xu <cgxu519@...ernel.net>
---
 fs/overlayfs/file.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index d081faa55e83..f9dc5249c183 100644
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -482,6 +482,12 @@ static int ovl_mmap(struct file *file, struct vm_area_struct *vma)
 	revert_creds(old_cred);
 	ovl_file_accessed(file);
 
+	if (!ret) {
+		if (ovl_inode_upper(file_inode(file)) &&
+		    vma->vm_flags & VM_SHARED)
+			ovl_mark_inode_dirty(file_inode(file));
+	}
+
 	return ret;
 }
 
-- 
2.27.0