Hi and thx for havp.
I'm running Linux, Ubuntu 8.04, and I think that the following could apply to my kernel:
http://www.mjmwired.net/kernel/Document ... ocking.txt :
Mandatory File Locking For The Linux Operating System
2
3 Andy Walker <andy[AT]lysaker.kvaerner[DOT]no>
4
5 15 April 1996
6 (Updated September 2007)
7
8 0. Why you should avoid mandatory locking
9 -----------------------------------------
10
11 The Linux implementation is prey to a number of difficult-to-fix race
12 conditions which in practice make it not dependable:
13
14 - The write system call checks for a mandatory lock only once
15 at its start. It is therefore possible for a lock request to
16 be granted after this check but before the data is modified.
17 A process may then see file data change even while a mandatory
18 lock was held.
19 - Similarly, an exclusive lock may be granted on a file after
20 the kernel has decided to proceed with a read, but before the
21 read has actually completed, and the reading process may see
22 the file data in a state which should not have been visible
23 to it.
24 - Similar races make the claimed mutual exclusion between lock
25 and mmap similarly unreliable.
Now I have only one disk partition on my proxy server running havp with clamav and squid, so I'd like to know why I should use mandatory lock for havp. If I don't use it what will be the consequences?
Best regards,
Andrea Ferraris