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SubjectRe: [PATCH 03/34] teach move_mount(2) to work with OPEN_TREE_CLONE [ver #12]
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Alan Jenkins <alan.christopher.jenkins@gmail.com> wrote:

> And the first sequence I mentioned - close the FD, then mount+unmount -
> seems to be unchanged.

Unchanged in what sense? Still breaks? I thought I'd fixed that - or are we
talking about a different first sequence?

Sorry, I'm losing track of how many different ways of breaking open_tree() and
move_mount() you've posted. I don't suppose you could post a checklist?

> I guess this tries to fix the second of the two sequences I mentioned -
> mount+unmount, then close the FD.  It doesn't seem to work.
>
> # open_tree_clone 3</mnt 3 sh
> # cd /proc/self/fd/3
> # mount --move . /mnt
> [ 41.747831] mnt_flags=1020 umount=0
> # cd /
> # umount /mnt
> umount: /mnt: target is busy
>
> ^ a newly introduced bug? I do not remember having this problem before.
>
> # umount -l /mnt

Sigh, so I see. I have the attached trace from this sequence.

David
----
Command "open_tree_clone 3</mnt 3 sh"

sh-3614 M=421a9872 u=1 ALC sp=clone_mnt+0x31/0x30a
sh-3614 M=421a9872 u=2 GET sp=do_dentry_open+0x24/0x2d3
sh-3614 M=421a9872 u=1 PUT sp=__se_sys_open_tree+0x195/0x1da
sh-3614 M=421a9872 u=2 GET sp=proc_fd_link+0x106/0x124
sh-3614 M=421a9872 u=1 PUT sp=vfs_statx+0x95/0xcc

Command "cd /proc/self/fd/3":

sh-3614 M=421a9872 u=2 GET sp=proc_fd_link+0x106/0x124
sh-3614 M=421a9872 u=3 GET sp=set_fs_pwd+0x37/0xdb
sh-3614 M=421a9872 u=2 PUT sp=ksys_chdir+0x88/0xbd

sh-3614 M=421a9872 u=3 GET sp=legitimize_path.isra.7+0x16/0x50
sh-3614 M=421a9872 u=2 PUT sp=vfs_statx+0x95/0xcc

Command "mount --move . /mnt":

sh-3614 M=421a9872 u=3 GET sp=copy_fs_struct+0xcc/0xde
mount-3615 M=421a9872 u=4 GET sp=legitimize_path.isra.7+0x16/0x50
mount-3615 M=421a9872 u=3 PUT sp=vfs_statx+0x95/0xcc
mount-3615 M=421a9872 u=4 GET sp=legitimize_path.isra.7+0x16/0x50
mount-3615 M=421a9872 u=5 GET sp=do_dentry_open+0x24/0x2d3
mount-3615 M=421a9872 u=4 PUT sp=terminate_walk+0x20/0xda
mount-3615 M=421a9872 u=5 GET sp=legitimize_path.isra.7+0x16/0x50
mount-3615 M=421a9872 u=4 PUT sp=vfs_statx+0x95/0xcc
mount-3615 M=421a9872 u=3 PUT sp=__fput+0x180/0x1c1
mount-3615 M=421a9872 u=4 GET sp=legitimize_path.isra.7+0x16/0x50
mount-3615 M=421a9872 u=4 0x4e sp= (null)
mount-3615 M=421a9872 u=5 GET sp=do_move_mount+0x216/0x298
mount-3615 M=421a9872 u=4 PUT sp=do_mount+0x715/0x929
mount-3615 M=421a9872 u=3 PUT sp=free_fs_struct+0x1e/0x2e

Command "cd /":

sh-3614 M=421a9872 u=2 PUT sp=set_fs_pwd+0xb8/0xdb

Command "umount /mnt":

umount-3616 M=421a9872 u=3 GET sp=legitimize_path.isra.7+0x16/0x50
umount-3616 M=421a9872 u=2 PUT sp=vfs_statx+0x95/0xcc
umount-3616 M=421a9872 u=3 GET sp=legitimize_path.isra.7+0x16/0x50
umount-3616 M=421a9872 u=2 PUT sp=vfs_statx+0x95/0xcc
umount-3616 M=421a9872 u=3 GET sp=legitimize_path.isra.7+0x16/0x50
umount-3616 M=421a9872 u=2 PUT sp=user_statfs+0x61/0x98
umount-3616 M=421a9872 u=3 GET sp=legitimize_mnt+0x12/0x108
umount-3616 M=421a9872 u=2 PUT sp=ksys_umount+0x3e8/0x40e

(Fails, -EBUSY).

Command "umount -l /mnt":

umount-3617 M=421a9872 u=3 GET sp=legitimize_mnt+0x12/0x108
umount-3617 M=421a9872 u=2 PUT sp=pin_kill+0x11c/0x325
umount-3617 M=421a9872 u=1 PUT sp=ksys_umount+0x3e8/0x40e

Command "exec 3<&-":

(Goes weird: bash still responds, but trying to run a command locks up that
shell; can still log in with ssh, but can't then run commands).

David

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