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authorChengguang Xu <cgxu519@zoho.com.cn>2019-08-20 18:03:25 +0800
committerDominique Martinet <dominique.martinet@cea.fr>2019-09-03 10:56:32 +0000
commitc87a37ebd40b889178664c2c09cc187334146292 (patch)
treeb22de8286db49fc7416431010267f6267c161da4
parent089cf7f6ecb266b6a4164919a2e69bd2f938374a (diff)
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 <cgxu519@zoho.com.cn> Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr>
-rw-r--r--fs/9p/vfs_file.c3
1 files changed, 3 insertions, 0 deletions
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);