=== remove the gate headroom (root, runtime sysctl) ===
vfs.hammer.limit_dirtybufspace: 51585024 -> 2097152
=== fresh fs, baseline ===
TEST         424M   178M   246M    42%    /mnt/h1
10 allocs, 1.59K in-use
reservation-failed-prints=0
=== attack: unprivileged 6-writer race past the real blockmap end ===
[1] 2188
[2] 2189
[3] 2190
[4] 2191
[5] 2192
[6] 2197
[6]  - Done                          /tmp/writers.sh s6 20 40
[5]  + Done                          /tmp/writers.sh s5 20 32
[4]  + Done                          /tmp/writers.sh s4 20 24
[3]  + Done                          /tmp/writers.sh s3 20 16
[2]  + Done                          /tmp/writers.sh s2 20 8
[1]  + Done                          /tmp/writers.sh s1 20 0
TEST         424M   424M     0B   100%    /mnt/h1
184 allocs, 30.5K in-use
reservation-failed-prints=0
=== persistence: rm everything, sync, wait ===
208 allocs, 35.7K in-use
reservation-failed-prints=0
=== restore default sysctl ===
vfs.hammer.limit_dirtybufspace: 2097152 -> 51585024
TEST         424M   225M   199M    53%    /mnt/h1
=== done ===