diff options
Diffstat (limited to 'fs/overlayfs/super.c')
| -rw-r--r-- | fs/overlayfs/super.c | 94 |
1 files changed, 73 insertions, 21 deletions
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 2e0fc93c2c06..0116735cc321 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -472,6 +472,7 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config) { char *p; int err; + bool metacopy_opt = false, redirect_opt = false; config->redirect_mode = kstrdup(ovl_redirect_mode_def(), GFP_KERNEL); if (!config->redirect_mode) @@ -516,6 +517,7 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config) config->redirect_mode = match_strdup(&args[0]); if (!config->redirect_mode) return -ENOMEM; + redirect_opt = true; break; case OPT_INDEX_ON: @@ -548,6 +550,7 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config) case OPT_METACOPY_ON: config->metacopy = true; + metacopy_opt = true; break; case OPT_METACOPY_OFF: @@ -572,13 +575,32 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config) if (err) return err; - /* metacopy feature with upper requires redirect_dir=on */ - if (config->upperdir && config->metacopy && !config->redirect_dir) { - pr_warn("overlayfs: metadata only copy up requires \"redirect_dir=on\", falling back to metacopy=off.\n"); - config->metacopy = false; - } else if (config->metacopy && !config->redirect_follow) { - pr_warn("overlayfs: metadata only copy up requires \"redirect_dir=follow\" on non-upper mount, falling back to metacopy=off.\n"); - config->metacopy = false; + /* + * This is to make the logic below simpler. It doesn't make any other + * difference, since config->redirect_dir is only used for upper. + */ + if (!config->upperdir && config->redirect_follow) + config->redirect_dir = true; + + /* Resolve metacopy -> redirect_dir dependency */ + if (config->metacopy && !config->redirect_dir) { + if (metacopy_opt && redirect_opt) { + pr_err("overlayfs: conflicting options: metacopy=on,redirect_dir=%s\n", + config->redirect_mode); + return -EINVAL; + } + if (redirect_opt) { + /* + * There was an explicit redirect_dir=... that resulted + * in this conflict. + */ + pr_info("overlayfs: disabling metacopy due to redirect_dir=%s\n", + config->redirect_mode); + config->metacopy = false; + } else { + /* Automatically enable redirect otherwise. */ + config->redirect_follow = config->redirect_dir = true; + } } return 0; @@ -982,16 +1004,6 @@ static int ovl_get_upper(struct ovl_fs *ofs, struct path *upperpath) if (err) goto out; - err = -EBUSY; - if (ovl_inuse_trylock(upperpath->dentry)) { - ofs->upperdir_locked = true; - } else if (ofs->config.index) { - pr_err("overlayfs: upperdir is in-use by another mount, mount with '-o index=off' to override exclusive upperdir protection.\n"); - goto out; - } else { - pr_warn("overlayfs: upperdir is in-use by another mount, accessing files from both mounts will result in undefined behavior.\n"); - } - upper_mnt = clone_private_mount(upperpath); err = PTR_ERR(upper_mnt); if (IS_ERR(upper_mnt)) { @@ -1002,6 +1014,17 @@ static int ovl_get_upper(struct ovl_fs *ofs, struct path *upperpath) /* Don't inherit atime flags */ upper_mnt->mnt_flags &= ~(MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME); ofs->upper_mnt = upper_mnt; + + err = -EBUSY; + if (ovl_inuse_trylock(ofs->upper_mnt->mnt_root)) { + ofs->upperdir_locked = true; + } else if (ofs->config.index) { + pr_err("overlayfs: upperdir is in-use by another mount, mount with '-o index=off' to override exclusive upperdir protection.\n"); + goto out; + } else { + pr_warn("overlayfs: upperdir is in-use by another mount, accessing files from both mounts will result in undefined behavior.\n"); + } + err = 0; out: return err; @@ -1101,8 +1124,10 @@ static int ovl_get_workdir(struct ovl_fs *ofs, struct path *upperpath) goto out; } + ofs->workbasedir = dget(workpath.dentry); + err = -EBUSY; - if (ovl_inuse_trylock(workpath.dentry)) { + if (ovl_inuse_trylock(ofs->workbasedir)) { ofs->workdir_locked = true; } else if (ofs->config.index) { pr_err("overlayfs: workdir is in-use by another mount, mount with '-o index=off' to override exclusive workdir protection.\n"); @@ -1111,7 +1136,6 @@ static int ovl_get_workdir(struct ovl_fs *ofs, struct path *upperpath) pr_warn("overlayfs: workdir is in-use by another mount, accessing files from both mounts will result in undefined behavior.\n"); } - ofs->workbasedir = dget(workpath.dentry); err = ovl_make_workdir(ofs, &workpath); if (err) goto out; @@ -1173,9 +1197,29 @@ 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; @@ -1189,6 +1233,14 @@ 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"); @@ -1223,7 +1275,7 @@ 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; |