Re: kern/49175 (removing large sparse file freeze the system)

[jdolecek%NetBSD.org@localhost]

Synopsis: removing large sparse file freeze the system

Responsible-Changed-From-To: kern-bug-people->jdolecek
Responsible-Changed-By: jdolecek%NetBSD.org@localhost
Responsible-Changed-When: Mon, 22 Aug 2016 20:55:33 +0000
Responsible-Changed-Why:
I'm looking into this


State-Changed-From-To: open->analyzed
State-Changed-By: jdolecek%NetBSD.org@localhost
State-Changed-When: Mon, 22 Aug 2016 20:55:33 +0000
State-Changed-Why:
I'm investigating how to best tackle this. First of all, I'd like to change code
in wapbl_flush() to actually flush the record also when there are some
dealloc registration - wapbl_start() calls the flush only for wapbl_flush() to
ignore the call since it skips the actual flush if (!waitfor) and wl_bufcount
is zero.
Second, I'd like to investigate if it would be possible to change the 
ffs_truncate() to do some kind of partial truncate and return (with READER lock)
so that we wouldn't need to get exclusive access and wouldn't need the silly
repeatable truncate unless there is not enough deallocation slots.