diff options
Diffstat (limited to 'fs/overlayfs/super.c')
| -rw-r--r-- | fs/overlayfs/super.c | 32 |
1 files changed, 30 insertions, 2 deletions
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 30adc9d408a0..22ffb23ea44d 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -1175,9 +1175,29 @@ out: return err; } +static bool ovl_lower_uuid_ok(struct ovl_fs *ofs, const uuid_t *uuid) +{ + unsigned int i; + + if (!ofs->config.nfs_export && !(ofs->config.index && ofs->upper_mnt)) + return true; + + for (i = 0; i < ofs->numlowerfs; i++) { + /* + * We use uuid to associate an overlay lower file handle with a + * lower layer, so we can accept lower fs with null uuid as long + * as all lower layers with null uuid are on the same fs. + */ + if (uuid_equal(&ofs->lower_fs[i].sb->s_uuid, uuid)) + return false; + } + return true; +} + /* Get a unique fsid for the layer */ -static int ovl_get_fsid(struct ovl_fs *ofs, struct super_block *sb) +static int ovl_get_fsid(struct ovl_fs *ofs, const struct path *path) { + struct super_block *sb = path->mnt->mnt_sb; unsigned int i; dev_t dev; int err; @@ -1191,6 +1211,14 @@ static int ovl_get_fsid(struct ovl_fs *ofs, struct super_block *sb) return i + 1; } + if (!ovl_lower_uuid_ok(ofs, &sb->s_uuid)) { + ofs->config.index = false; + ofs->config.nfs_export = false; + pr_warn("overlayfs: %s uuid detected in lower fs '%pd2', falling back to index=off,nfs_export=off.\n", + uuid_is_null(&sb->s_uuid) ? "null" : "conflicting", + path->dentry); + } + err = get_anon_bdev(&dev); if (err) { pr_err("overlayfs: failed to get anonymous bdev for lowerpath\n"); @@ -1225,7 +1253,7 @@ static int ovl_get_lower_layers(struct ovl_fs *ofs, struct path *stack, struct vfsmount *mnt; int fsid; - err = fsid = ovl_get_fsid(ofs, stack[i].mnt->mnt_sb); + err = fsid = ovl_get_fsid(ofs, &stack[i]); if (err < 0) goto out; |