From: Amir Goldstein <amir73il@gmail.com>
To: Miklos Szeredi <miklos@szeredi.hu>
Cc: Colin Ian King <colin.king@canonical.com>, linux-unionfs@vger.kernel.org
Subject: [PATCH 1/6] ovl: fix corner case of non-unique st_dev;st_ino
Date: Sun, 17 Nov 2019 17:43:44 +0200 [thread overview]
Message-ID: <20191117154349.28695-2-amir73il@gmail.com> (raw)
In-Reply-To: <20191117154349.28695-1-amir73il@gmail.com>
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>
---
fs/overlayfs/inode.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
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;
}
/*
--
2.17.1
next prev parent reply other threads:[~2019-11-17 15:43 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-17 15:43 [PATCH 0/6] Sort out overlay layers and fs arrays Amir Goldstein
2019-11-17 15:43 ` Amir Goldstein [this message]
2019-11-17 15:43 ` [PATCH 2/6] ovl: generalize the lower_layers[] array Amir Goldstein
2019-11-17 15:43 ` [PATCH 3/6] ovl: simplify ovl_same_sb() helper Amir Goldstein
2019-11-17 15:43 ` [PATCH 4/6] ovl: generalize the lower_fs[] array Amir Goldstein
2019-11-18 17:01 ` Amir Goldstein
2019-11-17 15:43 ` [PATCH 5/6] ovl: fix corner case of conflicting lower layer uuid Amir Goldstein
2019-11-17 15:43 ` [PATCH 6/6] ovl: fix corner case of non-constant st_dev;st_ino Amir Goldstein
2019-11-18 6:03 ` [PATCH 0/6] Sort out overlay layers and fs arrays Amir Goldstein
2019-11-18 7:57 ` Amir Goldstein
2019-11-22 9:31 ` Amir Goldstein
2019-11-25 14:45 ` Amir Goldstein
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