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| author | Amir Goldstein <amir73il@gmail.com> | 2019-11-17 17:43:44 +0200 |
|---|---|---|
| committer | Miklos Szeredi <mszeredi@redhat.com> | 2019-12-10 16:00:55 +0100 |
| commit | 9c6d8f13e9da10a26ad7f0a020ef86e8ef142835 (patch) | |
| tree | db5a644e905250ecdc801a262a8cf6ef27366995 /fs/overlayfs/inode.c | |
| parent | ec7bbb53d339250df7d4b042ff93c468535c0a90 (diff) | |
| download | linux-9c6d8f13e9da10a26ad7f0a020ef86e8ef142835.tar.bz2 | |
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/inode.c')
| -rw-r--r-- | fs/overlayfs/inode.c | 8 |
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; } /* |