Merge branch 'overlayfs-next' of git://git.kernel.org/pub/scm/linux/kernel/git/mszere...

Pull overlayfs fixes from Miklos Szeredi:
 "This fixes minor issues with the multi-layer update in v4.0"

* 'overlayfs-next' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: upper fs should not be R/O
  ovl: check lowerdir amount for non-upper mount
  ovl: print error message for invalid mount options

diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index b90952f528b1cdf7414e49b5613e439d6b89fb7a..5f0d1993e6e3952bda9352d231e8fce7dee838e8 100644 (file)
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -529,8 +529,7 @@ static int ovl_remount(struct super_block *sb, int *flags, char *data)
 {
        struct ovl_fs *ufs = sb->s_fs_info;
 
-       if (!(*flags & MS_RDONLY) &&
-           (!ufs->upper_mnt || (ufs->upper_mnt->mnt_sb->s_flags & MS_RDONLY)))
+       if (!(*flags & MS_RDONLY) && !ufs->upper_mnt)
                return -EROFS;
 
        return 0;
@@ -615,9 +614,19 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config)
                        break;
 
                default:
+                       pr_err("overlayfs: unrecognized mount option \"%s\" or missing value\n", p);
                        return -EINVAL;
                }
        }
+
+       /* Workdir is useless in non-upper mount */
+       if (!config->upperdir && config->workdir) {
+               pr_info("overlayfs: option \"workdir=%s\" is useless in a non-upper mount, ignore\n",
+                       config->workdir);
+               kfree(config->workdir);
+               config->workdir = NULL;
+       }
+
        return 0;
 }
 
@@ -837,7 +846,6 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
 
        sb->s_stack_depth = 0;
        if (ufs->config.upperdir) {
-               /* FIXME: workdir is not needed for a R/O mount */
                if (!ufs->config.workdir) {
                        pr_err("overlayfs: missing 'workdir'\n");
                        goto out_free_config;
@@ -847,6 +855,13 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
                if (err)
                        goto out_free_config;
 
+               /* Upper fs should not be r/o */
+               if (upperpath.mnt->mnt_sb->s_flags & MS_RDONLY) {
+                       pr_err("overlayfs: upper fs is r/o, try multi-lower layers mount\n");
+                       err = -EINVAL;
+                       goto out_put_upperpath;
+               }
+
                err = ovl_mount_dir(ufs->config.workdir, &workpath);
                if (err)
                        goto out_put_upperpath;
@@ -869,8 +884,14 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
 
        err = -EINVAL;
        stacklen = ovl_split_lowerdirs(lowertmp);
-       if (stacklen > OVL_MAX_STACK)
+       if (stacklen > OVL_MAX_STACK) {
+               pr_err("overlayfs: too many lower directries, limit is %d\n",
+                      OVL_MAX_STACK);
                goto out_free_lowertmp;
+       } else if (!ufs->config.upperdir && stacklen == 1) {
+               pr_err("overlayfs: at least 2 lowerdir are needed while upperdir nonexistent\n");
+               goto out_free_lowertmp;
+       }
 
        stack = kcalloc(stacklen, sizeof(struct path), GFP_KERNEL);
        if (!stack)
@@ -932,8 +953,8 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
                ufs->numlower++;
        }
 
-       /* If the upper fs is r/o or nonexistent, we mark overlayfs r/o too */
-       if (!ufs->upper_mnt || (ufs->upper_mnt->mnt_sb->s_flags & MS_RDONLY))
+       /* If the upper fs is nonexistent, we mark overlayfs r/o too */
+       if (!ufs->upper_mnt)
                sb->s_flags |= MS_RDONLY;
 
        sb->s_d_op = &ovl_dentry_operations;