Thanks a lot for your comments.
>I must say I have a very uneasy feeling about such a usage and
>don't know how it is covered by standards (although you claim it works for
non
>linux). Experience shows that such a construct is very
>fragile. Note also that NFS file locking is not mandatory, only advisory
(read:
>user level) and it is unclear how that will interact with mmap.
I agree that the construction is very fragile, but...
- It's been working on a variety of OSes for years... There is no reason for
Linux not to support it as a mature operating system.
- This works for read/write system calls if the file is open with O_SYNC
flag and NFS is mounted using "sync" option.
- There has to be something in the OS that users can do to unconditionally
reread mapped files (no matter if this is NFS or not)
- Even mandatory locking should be sufficient for mmap interaction if one
cares to flush information to the disk before the file is unlocked.
Suprisingly, locking is not the problem here :)
Best,
Giga
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