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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 <vbatts@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Tested-by: Jordi Pujol Palomer <jordipujolp@gmail.com>
Fixes: 263b4a0fee ("ovl: dont replace opaque dir")
Cc: <stable@vger.kernel.org> # v4.0+
This commit is contained in:
Miklos Szeredi 2015-05-14 10:04:44 +02:00
parent 030bbdbf4c
commit d377c5eb54
1 changed files with 19 additions and 5 deletions
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24
fs/overlayfs/dir.c
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@ -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);