From d377c5eb54dd05aeb3094b7740252d19ba7791f7 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Thu, 14 May 2015 10:04:44 +0200 Subject: ovl: don't remove non-empty opaque directory When removing an opaque directory we can't just call rmdir() to check for emptiness, because the directory will need to be replaced with a whiteout. The replacement is done with RENAME_EXCHANGE, which doesn't check emptiness. Solution is just to check emptiness by reading the directory. In the future we could add a new rename flag to check for emptiness even for RENAME_EXCHANGE to optimize this case. Reported-by: Vincent Batts Signed-off-by: Miklos Szeredi Tested-by: Jordi Pujol Palomer Fixes: 263b4a0fee43 ("ovl: dont replace opaque dir") Cc: # v4.0+ --- fs/overlayfs/dir.c | 24 +++++++++++++++++++----- 1 file changed, 19 insertions(+), 5 deletions(-) (limited to 'fs') diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c index d139405d2bfa..2578a0c0677d 100644 --- a/fs/overlayfs/dir.c +++ b/fs/overlayfs/dir.c @@ -506,11 +506,25 @@ static int ovl_remove_and_whiteout(struct dentry *dentry, bool is_dir) struct dentry *opaquedir = NULL; int err; - if (is_dir && OVL_TYPE_MERGE_OR_LOWER(ovl_path_type(dentry))) { - opaquedir = ovl_check_empty_and_clear(dentry); - err = PTR_ERR(opaquedir); - if (IS_ERR(opaquedir)) - goto out; + if (is_dir) { + if (OVL_TYPE_MERGE_OR_LOWER(ovl_path_type(dentry))) { + opaquedir = ovl_check_empty_and_clear(dentry); + err = PTR_ERR(opaquedir); + if (IS_ERR(opaquedir)) + goto out; + } else { + LIST_HEAD(list); + + /* + * When removing an empty opaque directory, then it + * makes no sense to replace it with an exact replica of + * itself. But emptiness still needs to be checked. + */ + err = ovl_check_empty_dir(dentry, &list); + ovl_cache_free(&list); + if (err) + goto out; + } } err = ovl_lock_rename_workdir(workdir, upperdir); -- cgit v1.2.3 From cc6f67bcafcb6bbbb2d1be1603dcd95125a52800 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Tue, 19 May 2015 14:30:12 +0200 Subject: ovl: mount read-only if workdir can't be created 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 Signed-off-by: Miklos Szeredi Cc: # v3.18+ --- fs/overlayfs/copy_up.c | 3 +++ fs/overlayfs/dir.c | 9 +++++++++ fs/overlayfs/super.c | 10 +++++----- 3 files changed, 17 insertions(+), 5 deletions(-) (limited to 'fs') diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c index 24f640441bd9..84d693d37428 100644 --- a/fs/overlayfs/copy_up.c +++ b/fs/overlayfs/copy_up.c @@ -299,6 +299,9 @@ int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry, struct cred *override_cred; char *link = NULL; + if (WARN_ON(!workdir)) + return -EROFS; + ovl_path_upper(parent, &parentpath); upperdir = parentpath.dentry; diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c index 2578a0c0677d..692ceda3bc21 100644 --- a/fs/overlayfs/dir.c +++ b/fs/overlayfs/dir.c @@ -222,6 +222,9 @@ static struct dentry *ovl_clear_empty(struct dentry *dentry, 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(struct dentry *dentry, struct inode *inode, 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(struct dentry *dentry, bool is_dir) 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); diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 5f0d1993e6e3..bf8537c7f455 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -529,7 +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) + if (!(*flags & MS_RDONLY) && (!ufs->upper_mnt || !ufs->workdir)) return -EROFS; return 0; @@ -925,9 +925,10 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) 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++) -- cgit v1.2.3