On Thu, May 22, 2025 at 5:22 PM André Almeida <andrealmeid@xxxxxxxxxx> wrote: > > Em 22/05/2025 12:13, Amir Goldstein escreveu: > > cc libfuse maintainer > > > > On Thu, May 22, 2025 at 4:30 PM André Almeida <andrealmeid@xxxxxxxxxx> wrote: > >> > >> Em 22/05/2025 06:52, Amir Goldstein escreveu: > >>> On Thu, May 22, 2025 at 8:20 AM André Almeida <andrealmeid@xxxxxxxxxx> wrote: > >>>> > >>>> Hi Christian, Amir, > >>>> > >>>> Thanks for the feedback :) > >>>> > >>>> Em 21/05/2025 08:20, Christian Brauner escreveu: > >>>>> On Wed, May 21, 2025 at 12:35:57PM +0200, Amir Goldstein wrote: > >>>>>> On Wed, May 21, 2025 at 8:45 AM André Almeida <andrealmeid@xxxxxxxxxx> wrote: > >>>>>>> > >>>> > >>>> [...] > >>>> > >>>>>> > >>>>>> I see the test generic/623 failure - this test needs to be fixed for overlay > >>>>>> or not run on overlayfs. > >>>>>> > >>>>>> I do not see those other 5 failures although before running the test I did: > >>>>>> export LIBMOUNT_FORCE_MOUNT2=always > >>>>>> > >>>>>> Not sure what I am doing differently. > >>>>>> > >>>> > >>>> I have created a smaller reproducer for this, have a look: > >>>> > >>>> mkdir -p ovl/lower ovl/upper ovl/merge ovl/work ovl/mnt > >>>> sudo mount -t overlay overlay -o lowerdir=ovl/lower,upperdir=ovl/ > >>>> upper,workdir=ovl/work ovl/mnt > >>>> sudo mount ovl/mnt -o remount,ro > >>>> > >>> > >>> Why would you use this command? > >>> Why would you want to re-specify the lower/upperdir when remounting ro? > >>> And more specifically, fstests does not use this command in the tests > >>> that you mention that they fail, so what am I missing? > >>> > >> > >> I've added "set -x" to tests/generic/294 to see exactly which mount > >> parameters were being used and I got this from the output: > >> > >> + _try_scratch_mount -o remount,ro > >> + local mount_ret > >> + '[' overlay == overlay ']' > >> + _overlay_scratch_mount -o remount,ro > >> + echo '-o remount,ro' > >> + grep -q remount > >> + /usr/bin/mount /tmp/dir2/ovl-mnt -o remount,ro > >> mount: /tmp/dir2/ovl-mnt: fsconfig() failed: ... > >> > >> So, from what I can see, fstests is using this command. Not sure if I > >> did something wrong when setting up fstests. > >> > > > > No you are right, I misread your reproducer. > > The problem is that my test machine has older libmount 2.38.1 > > without the new mount API. > > > > > >>>> And this returns: > >>>> > >>>> mount: /tmp/ovl/mnt: fsconfig() failed: overlay: No changes allowed in > >>>> reconfigure. > >>>> dmesg(1) may have more information after failed mount system call. > >>>> > >>>> However, when I use mount like this: > >>>> > >>>> sudo mount -t overlay overlay -o remount,ro ovl/mnt > >>>> > >>>> mount succeeds. Having a look at strace, I found out that the first > >>>> mount command tries to set lowerdir to "ovl/lower" again, which will to > >>>> return -EINVAL from ovl_parse_param(): > >>>> > >>>> fspick(3, "", FSPICK_NO_AUTOMOUNT|FSPICK_EMPTY_PATH) = 4 > >>>> fsconfig(4, FSCONFIG_SET_STRING, "lowerdir", "/tmp/ovl/lower", 0) = > >>>> -1 EINVAL (Invalid argument) > >>>> > >>>> Now, the second mount command sets just the "ro" flag, which will return > >>>> after vfs_parse_sb_flag(), before getting to ovl_parse_param(): > >>>> > >>>> fspick(3, "", FSPICK_NO_AUTOMOUNT|FSPICK_EMPTY_PATH) = 4 > >>>> fsconfig(4, FSCONFIG_SET_FLAG, "ro", NULL, 0) = 0 > >>>> > >>>> After applying my patch and running the first mount command again, we > >>>> can set that this flag is set only after setting all the strings: > >>>> > >>>> fsconfig(4, FSCONFIG_SET_STRING, "lowerdir", "/tmp/ovl/lower", 0) = 0 > >>>> fsconfig(4, FSCONFIG_SET_STRING, "upperdir", "/tmp/ovl/upper", 0) = 0 > >>>> fsconfig(4, FSCONFIG_SET_STRING, "workdir", "/tmp/ovl/work", 0) = 0 > >>>> fsconfig(4, FSCONFIG_SET_STRING, "uuid", "on", 0) = 0 > >>>> fsconfig(4, FSCONFIG_SET_FLAG, "ro", NULL, 0) = 0 > >>>> > >>>> I understood that the patch that I proposed is wrong, and now I wonder > >>>> if the kernel needs to be fixed at all, or if the bug is how mount is > >>>> using fsconfig() in the first mount command? > >>> > > > > If you ask me, when a user does: > > /usr/bin/mount /tmp/dir2/ovl-mnt -o remount,ro > > > > The library only needs to do the FSCONFIG_SET_FLAG command and has no > > business re-sending the other config commands, but that's just me. > > > > Yes, this makes sense to me as well. > > > BTW, which version of libmount (mount --version) are you using? > > I think there were a few problematic versions when the new mount api > > was first introduced. > > > > mount from util-linux 2.41 (libmount 2.41.0: btrfs, verity, namespaces, > idmapping, fd-based-mount, statmount, assert, debug) > All right, I upgraded my test machine to a newer distro so I see those errors. I will post a patch to xfstests to use LIBMOUNT_FORCE_MOUNT2 for overlayfs remount. Thanks, Amir.
