From: Miklos Szeredi Date: Thu, 14 May 2015 10:04:44 +0200 Subject: [PATCH] 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(-) 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);