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When nfsd_cross_mnt() sets LOOKUP_AUTOMOUNT for a snapdir entry and follow_down() returns with the path unchanged, the automount was attempted and failed (EISDIR from zfsctl_snapshot_mount). The existing code treats this as "mountpoint in some other namespace" and returns success with the ctldir stub dentry. This stub has simple_dir_operations and produces a 44-byte file handle that returns empty READDIR (NFS4_OK, zero entries) with no error signal for the client to trigger re-resolution. This can happen transiently when zfs_suspend_fs races with mount helper after the z_teardown_lock deadlock fix (openzfs/zfs#18415) Return ESTALE for snapdir entries so the client retries via LOOKUP, which re-triggers the automount. Signed-off-by: Ameer Hamza <ahamza@ixsystems.com> (cherry picked from commit c026341)
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Apr 8, 2026
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When nfsd_cross_mnt() sets LOOKUP_AUTOMOUNT for a snapdir entry and follow_down() returns with the path unchanged, the automount was attempted and failed (EISDIR from zfsctl_snapshot_mount). The existing code treats this as "mountpoint in some other namespace" and returns success with the ctldir stub dentry. This stub has simple_dir_operations and produces a 44-byte file handle that returns empty READDIR (NFS4_OK, zero entries) with no error signal for the client to trigger re-resolution. This can happen transiently when zfs_suspend_fs races with mount helper after the z_teardown_lock deadlock fix (openzfs/zfs#18415)
Return
ESTALEfor snapdir entries so the client retries via LOOKUP, which re-triggers the automount.Original PR: #247