From: Filipe Manana <fdmanana@xxxxxxxxxx>
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@xxxxxxxxxx>
---
libmount/src/optlist.c | 13 ++++++++++++-
tests/expected/libmount/context-mount-flags | 3 +++
tests/ts/libmount/context | 9 ++++++++-
3 files changed, 23 insertions(+), 2 deletions(-)
diff --git a/libmount/src/optlist.c b/libmount/src/optlist.c
index e93810b47..d0afc94f7 100644
--- a/libmount/src/optlist.c
+++ b/libmount/src/optlist.c
@@ -875,7 +875,18 @@ int mnt_optlist_get_attrs(struct libmnt_optlist *ls, uint64_t *set, uint64_t *cl
if (opt->ent->mask & MNT_INVERT) {
DBG(OPTLIST, ul_debugobj(ls, " clr: %s", opt->ent->name));
- *clr |= x;
+ /*
+ * All atime settings are mutually exclusive so *clr must
+ * have MOUNT_ATTR__ATIME set.
+ *
+ * See the function fs/namespace.c:build_mount_kattr()
+ * in the linux kernel source.
+ */
+ if (x == MOUNT_ATTR_RELATIME || x == MOUNT_ATTR_NOATIME ||
+ x == MOUNT_ATTR_STRICTATIME)
+ *clr |= MOUNT_ATTR__ATIME;
+ else
+ *clr |= x;
} else {
DBG(OPTLIST, ul_debugobj(ls, " set: %s", opt->ent->name));
*set |= x;
diff --git a/tests/expected/libmount/context-mount-flags b/tests/expected/libmount/context-mount-flags
index 960641863..eb71323dd 100644
--- a/tests/expected/libmount/context-mount-flags
+++ b/tests/expected/libmount/context-mount-flags
@@ -3,3 +3,6 @@ ro,nosuid,noexec
successfully mounted
rw,nosuid,noexec
successfully umounted
+successfully mounted
+rw,relatime
+successfully umounted
diff --git a/tests/ts/libmount/context b/tests/ts/libmount/context
index f5b47185e..a5d2e81a3 100755
--- a/tests/ts/libmount/context
+++ b/tests/ts/libmount/context
@@ -116,8 +116,15 @@ $TS_CMD_FINDMNT --kernel --mountpoint $MOUNTPOINT -o VFS-OPTIONS -n >> $TS_OUTPU
ts_run $TESTPROG --umount $MOUNTPOINT >> $TS_OUTPUT 2>> $TS_ERRLOG
is_mounted $DEVICE && echo "$DEVICE still mounted" >> $TS_OUTPUT 2>> $TS_ERRLOG
-ts_finalize_subtest
+# Test that the atime option works after the migration to use the new kernel mount APIs.
+ts_run $TESTPROG --mount -o atime $DEVICE $MOUNTPOINT >> $TS_OUTPUT 2>> $TS_ERRLOG
+$TS_CMD_FINDMNT --kernel --mountpoint $MOUNTPOINT -o VFS-OPTIONS -n >> $TS_OUTPUT 2>> $TS_ERRLOG
+is_mounted $DEVICE || echo "$DEVICE not mounted" >> $TS_OUTPUT 2>> $TS_ERRLOG
+ts_run $TESTPROG --umount $MOUNTPOINT >> $TS_OUTPUT 2>> $TS_ERRLOG
+is_mounted $DEVICE && echo "$DEVICE still mounted" >> $TS_OUTPUT 2>> $TS_ERRLOG
+
+ts_finalize_subtest
ts_init_subtest "mount-loopdev"
mkdir -p $MOUNTPOINT &> /dev/null
--
2.40.1
