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,roWhy 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)
Thanks, Amir.
