From c87a37ebd40b889178664c2c09cc187334146292 Mon Sep 17 00:00:00 2001 From: Chengguang Xu Date: Tue, 20 Aug 2019 18:03:25 +0800 Subject: 9p: avoid attaching writeback_fid on mmap with type PRIVATE Currently on mmap cache policy, we always attach writeback_fid whether mmap type is SHARED or PRIVATE. However, in the use case of kata-container which combines 9p(Guest OS) with overlayfs(Host OS), this behavior will trigger overlayfs' copy-up when excute command inside container. Link: http://lkml.kernel.org/r/20190820100325.10313-1-cgxu519@zoho.com.cn Signed-off-by: Chengguang Xu Signed-off-by: Dominique Martinet --- fs/9p/vfs_file.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'fs/9p') diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c index 4cc966a31cb3..fe7f0bd2048e 100644 --- a/fs/9p/vfs_file.c +++ b/fs/9p/vfs_file.c @@ -513,6 +513,7 @@ v9fs_mmap_file_mmap(struct file *filp, struct vm_area_struct *vma) v9inode = V9FS_I(inode); mutex_lock(&v9inode->v_mutex); if (!v9inode->writeback_fid && + (vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_WRITE)) { /* * clone a fid and add it to writeback_fid @@ -614,6 +615,8 @@ static void v9fs_mmap_vm_close(struct vm_area_struct *vma) (vma->vm_end - vma->vm_start - 1), }; + if (!(vma->vm_flags & VM_SHARED)) + return; p9_debug(P9_DEBUG_VFS, "9p VMA close, %p, flushing", vma); -- cgit