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vfs_domount_update(): postpone setting MNT_UNION until VFS_MOUNT() is done
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Authored by kib on Wed, May 15, 10:01 AM.
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Details

Summary
The file system that handles updating the mount point might do lookups
during the update, in which case it could find the flag MNT_UNION set on
the mp while mount point is still not updated.  In particular, the
rootvp->v_mount->mnt_vnodecovered is not yet set.

Delay setting MNT_UNION until the mount is performed.

PR:     265311
Reported by:    Robert Morris <rtm@lcs.mit.edu>

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rG FreeBSD src repository
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kib requested review of this revision.Wed, May 15, 10:01 AM

This looks like the correct fix. One other unrelated nit.

sys/kern/vfs_mount.c
1526

Incorrect <tab> rather than <space> between &= and ~(MNT_UPDATE.

This revision is now accepted and ready to land.Wed, May 15, 7:47 PM