[issue1583] panic: assertion: cursor->trans->sync_lock_refs > 0 in hammer_recover_cursor

[Joe "Floid" Kanowitz (via DragonFly issue tracker)]

Joe "Floid" Kanowitz <jkanowitz at snet.net> added the comment:

Contents of patch applied to 2.4, no ill effects noted.  With the PFSes
mostly-synchronized I didn't have enough data left to sync to test for the same
failure with multiple `mirror-copy`s running, but I'll be setting up parallel
mirror-streams shortly as required for my setup.  (Is there a convenient way to
destroy a PFS and make sure it gets recreated with the same PFS number?)


I briefly thought the low I/O figures on da1 (mirroring from da0 to da1) might
have been a new quirk:

# hammer mirror-copy /DATA/ /Mirror/pfs/DATA
histogram range 0000000107e975cf - 000000010d6514f0
Mirror-read: Mirror from 0000000000000002 to 000000010d6514f0
Mirror-read /DATA/ succeeded

> iostat -w1
      tty             ad0              da0              da1             cpu
 tin tout  KB/t tps   MB/s   KB/t tps   MB/s   KB/t tps   MB/s  us ni sy in id
   2  465  0.00    0  0.00   0.00    0  0.00   0.00    0  0.00   4  0 10  1 85
   0   80  0.00    0  0.00  64.00  643 40.21  64.00    4  0.25  21  0 42  2 35
   0   80  0.00    0  0.00  63.82  683 42.59  60.00    4  0.23  28  0 37  3 32
   0   80  0.00    0  0.00  63.79  614 38.26  64.00    6  0.37  20  0 38  1 41

. ..but it completed in appropriate time and all the data appears to be there, so
I'm not sure if HAMMER was being smart enough to skip over what existed from a
previous interrupted copy or what.  I don't really remember whether the
pre-patch stats actually looked any different for the destination disk.

[SATA disks on a mpt0, write caches enabled.]

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