This is a note to let you know that I've just added the patch titled ovl: mount read-only if workdir can't be created to the 4.0-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: ovl-mount-read-only-if-workdir-can-t-be-created.patch and it can be found in the queue-4.0 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From cc6f67bcafcb6bbbb2d1be1603dcd95125a52800 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi <mszeredi@xxxxxxx> Date: Tue, 19 May 2015 14:30:12 +0200 Subject: ovl: mount read-only if workdir can't be created From: Miklos Szeredi <mszeredi@xxxxxxx> commit cc6f67bcafcb6bbbb2d1be1603dcd95125a52800 upstream. OpenWRT folks reported that overlayfs fails to mount if upper fs is full, because workdir can't be created. Wordir creation can fail for various other reasons too. There's no reason that the mount itself should fail, overlayfs can work fine without a workdir, as long as the overlay isn't modified. So mount it read-only and don't allow remounting read-write. Add a couple of WARN_ON()s for the impossible case of workdir being used despite being read-only. Reported-by: Bastian Bittorf <bittorf@xxxxxxxxxxxxxx> Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/overlayfs/copy_up.c | 3 +++ fs/overlayfs/dir.c | 9 +++++++++ fs/overlayfs/super.c | 10 +++++----- 3 files changed, 17 insertions(+), 5 deletions(-) --- a/fs/overlayfs/copy_up.c +++ b/fs/overlayfs/copy_up.c @@ -299,6 +299,9 @@ int ovl_copy_up_one(struct dentry *paren struct cred *override_cred; char *link = NULL; + if (WARN_ON(!workdir)) + return -EROFS; + ovl_path_upper(parent, &parentpath); upperdir = parentpath.dentry; --- a/fs/overlayfs/dir.c +++ b/fs/overlayfs/dir.c @@ -222,6 +222,9 @@ static struct dentry *ovl_clear_empty(st struct kstat stat; int err; + if (WARN_ON(!workdir)) + return ERR_PTR(-EROFS); + err = ovl_lock_rename_workdir(workdir, upperdir); if (err) goto out; @@ -322,6 +325,9 @@ static int ovl_create_over_whiteout(stru struct dentry *newdentry; int err; + if (WARN_ON(!workdir)) + return -EROFS; + err = ovl_lock_rename_workdir(workdir, upperdir); if (err) goto out; @@ -506,6 +512,9 @@ static int ovl_remove_and_whiteout(struc struct dentry *opaquedir = NULL; int err; + if (WARN_ON(!workdir)) + return -EROFS; + if (is_dir) { if (OVL_TYPE_MERGE_OR_LOWER(ovl_path_type(dentry))) { opaquedir = ovl_check_empty_and_clear(dentry); --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -529,7 +529,7 @@ static int ovl_remount(struct super_bloc { struct ovl_fs *ufs = sb->s_fs_info; - if (!(*flags & MS_RDONLY) && !ufs->upper_mnt) + if (!(*flags & MS_RDONLY) && (!ufs->upper_mnt || !ufs->workdir)) return -EROFS; return 0; @@ -925,9 +925,10 @@ static int ovl_fill_super(struct super_b ufs->workdir = ovl_workdir_create(ufs->upper_mnt, workpath.dentry); err = PTR_ERR(ufs->workdir); if (IS_ERR(ufs->workdir)) { - pr_err("overlayfs: failed to create directory %s/%s\n", - ufs->config.workdir, OVL_WORKDIR_NAME); - goto out_put_upper_mnt; + pr_warn("overlayfs: failed to create directory %s/%s (errno: %i); mounting read-only\n", + ufs->config.workdir, OVL_WORKDIR_NAME, -err); + sb->s_flags |= MS_RDONLY; + ufs->workdir = NULL; } } @@ -997,7 +998,6 @@ out_put_lower_mnt: kfree(ufs->lower_mnt); out_put_workdir: dput(ufs->workdir); -out_put_upper_mnt: mntput(ufs->upper_mnt); out_put_lowerpath: for (i = 0; i < numlower; i++) Patches currently in stable-queue which might be from mszeredi@xxxxxxx are queue-4.0/ovl-don-t-remove-non-empty-opaque-directory.patch queue-4.0/ovl-mount-read-only-if-workdir-can-t-be-created.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html