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authorAmir Goldstein <amir73il@gmail.com>2019-11-17 18:43:44 +0300
committerMiklos Szeredi <mszeredi@redhat.com>2019-12-10 18:00:55 +0300
commit9c6d8f13e9da10a26ad7f0a020ef86e8ef142835 (patch)
treedb5a644e905250ecdc801a262a8cf6ef27366995 /fs/overlayfs
parentec7bbb53d339250df7d4b042ff93c468535c0a90 (diff)
downloadlinux-9c6d8f13e9da10a26ad7f0a020ef86e8ef142835.tar.xz
ovl: fix corner case of non-unique st_dev;st_ino
On non-samefs overlay without xino, non pure upper inodes should use a pseudo_dev assigned to each unique lower fs and pure upper inodes use the real upper st_dev. It is fine for an overlay pure upper inode to use the same st_dev;st_ino values as the real upper inode, because the content of those two different filesystem objects is always the same. In this case, however: - two filesystems, A and B - upper layer is on A - lower layer 1 is also on A - lower layer 2 is on B Non pure upper overlay inode, whose origin is in layer 1 will have the same st_dev;st_ino values as the real lower inode. This may result with a false positive results of 'diff' between the real lower and copied up overlay inode. Fix this by using the upper st_dev;st_ino values in this case. This breaks the property of constant st_dev;st_ino across copy up of this case. This breakage will be fixed by a later patch. Fixes: 5148626b806a ("ovl: allocate anon bdev per unique lower fs") Cc: stable@vger.kernel.org # v4.17+ Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Diffstat (limited to 'fs/overlayfs')
-rw-r--r--fs/overlayfs/inode.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index bc14781886bf..b045cf1826fc 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -200,8 +200,14 @@ int ovl_getattr(const struct path *path, struct kstat *stat,
if (ovl_test_flag(OVL_INDEX, d_inode(dentry)) ||
(!ovl_verify_lower(dentry->d_sb) &&
(is_dir || lowerstat.nlink == 1))) {
- stat->ino = lowerstat.ino;
lower_layer = ovl_layer_lower(dentry);
+ /*
+ * Cannot use origin st_dev;st_ino because
+ * origin inode content may differ from overlay
+ * inode content.
+ */
+ if (samefs || lower_layer->fsid)
+ stat->ino = lowerstat.ino;
}
/*