libmount: Fix regression when mounting with atime
A regression was introduced in v2.39 that causes mounting with the atime
option to fail:
$ mkfs.ext4 -F /dev/sdi
$ mount -o atime /dev/sdi /mnt/sdi
mount: /mnt/sdi: not mount point or bad option.
dmesg(1) may have more information after failed mount system call.
The failure comes from the mount_setattr(2) call returning -EINVAL. This
is because we pass an invalid value for the attr_clr argument. From a
strace capture we have:
mount_setattr(4, "", AT_EMPTY_PATH, {attr_set=0, attr_clr=MOUNT_ATTR_NOATIME, propagation=0 /* MS_??? */, userns_fd=0}, 32) = -1 EINVAL (Invalid argument)
We can't pass MOUNT_ATTR_NOATIME to mount_setattr(2) through the attr_clr
argument because all atime options are exclusive, so in order to set atime
one has to pass MOUNT_ATTR__ATIME to attr_clr and leave attr_set as
MOUNT_ATTR_RELATIME (which is defined as a value of 0).
This can be read from the man page for mount_setattr(2) and also from the
kernel source:
$ cat fs/namespace.c
static int build_mount_kattr(const struct mount_attr *attr, size_t usize,
struct mount_kattr *kattr, unsigned int flags)
{
(...)
/*
* Since the MOUNT_ATTR_<atime> values are an enum, not a bitmap,
* users wanting to transition to a different atime setting cannot
* simply specify the atime setting in @attr_set, but must also
* specify MOUNT_ATTR__ATIME in the @attr_clr field.
* So ensure that MOUNT_ATTR__ATIME can't be partially set in
* @attr_clr and that @attr_set can't have any atime bits set if
* MOUNT_ATTR__ATIME isn't set in @attr_clr.
*/
if (attr->attr_clr & MOUNT_ATTR__ATIME) {
if ((attr->attr_clr & MOUNT_ATTR__ATIME) != MOUNT_ATTR__ATIME)
return -EINVAL;
/*
* Clear all previous time settings as they are mutually
* exclusive.
*/
kattr->attr_clr |= MNT_RELATIME | MNT_NOATIME;
switch (attr->attr_set & MOUNT_ATTR__ATIME) {
case MOUNT_ATTR_RELATIME:
kattr->attr_set |= MNT_RELATIME;
break;
case MOUNT_ATTR_NOATIME:
kattr->attr_set |= MNT_NOATIME;
break;
case MOUNT_ATTR_STRICTATIME:
break;
default:
return -EINVAL;
}
(...)
So fix this by setting attr_clr MOUNT_ATTR__ATIME if we want to clear any
atime related option.
Signed-off-by: Filipe Manana <fdmanana@kernel.org>
Closes: #1042714
Gbp-Pq: Topic upstream
Gbp-Pq: Name libmount-Fix-regression-when-mounting-with-atime.patch
projects / util-linux.git / log