O_APPEND support about libnfs

[sahlberg]

That is a really good idea.
I just pushed a change that adds O_APPEND support. Please try it out.

However, due to the race between GETATTR and WRITE, the same caveat exists in libnfs as for normal nfs with regards to O_APPEND. Just be aware.

Man 2 open
O_APPEND
The file is opened in append mode. Before each write(2), the
file offset is positioned at the end of the file, as if with
lseek(2). O_APPEND may lead to corrupted files on NFS filesys‐
tems if more than one process appends data to a file at once.
This is because NFS does not support appending to a file, so the
client kernel has to simulate it, which can't be done without a
race condition.

[rosslagerwall]

Seems to work well, thanks for the really fast response!