ovl: unbless lower st_ino of unverified origin (86eaa130) · Commits · 戴 / test

On a malformed overlay, several redirected dirs can point to the same dir on a lower layer. This presents a similar challenge as broken hardlinks, because different objects in the overlay can return the same st_ino/st_dev pair from stat(2). For broken hardlinks, we do not provide constant st_ino on copy up to avoid this inconsistency. When NFS export feature is enabled, apply the same logic to files and directories with unverified lower origin. Signed-off-by:

Amir Goldstein <amir73il@gmail.com> Signed-off-by:

Miklos Szeredi <mszeredi@redhat.com>

fs/overlayfs/inode.c

+12 −4

Original line number	Diff line number	Diff line
		@@ -105,12 +105,20 @@ int ovl_getattr(const struct path path, struct kstat stat,
		* Lower hardlinks may be broken on copy up to different
		* upper files, so we cannot use the lower origin st_ino
		* for those different files, even for the same fs case.
		*
		* Similarly, several redirected dirs can point to the
		* same dir on a lower layer. With the "verify_lower"
		* feature, we do not use the lower origin st_ino, if
		* we haven't verified that this redirect is unique.
		*
		* With inodes index enabled, it is safe to use st_ino
		* of an indexed hardlinked origin. The index validates
		* that the upper hardlink is not broken.
		* of an indexed origin. The index validates that the
		* upper hardlink is not broken and that a redirected
		* dir is the only redirect to that origin.
		*/
		if (is_dir \|\| lowerstat.nlink == 1 \|\|
		ovl_test_flag(OVL_INDEX, d_inode(dentry)))
		if (ovl_test_flag(OVL_INDEX, d_inode(dentry)) \|\|
		(!ovl_verify_lower(dentry->d_sb) &&
		(is_dir \|\| lowerstat.nlink == 1)))
		stat->ino = lowerstat.ino;

		if (samefs)

Admin message