Hi NFSDevs, I am recently testing linux nfs lock with NFS share from a WinServer 2016. I tried to write a file which has already been locked with fcntl exclusively, but the response of `write` syscall is neither `Permission denied`, nor successfully written with file content changed. Here is several experiments I did: The first shell runs c program, calling `fcntl` to lock file exclusively “fcntl(fd, F_SETLKW, &fl)” 2.1 The second shell tried to open with flag O_RDWR, and write a buffer to the same file, write returned the correct bytes written, but the file content remained unchanged. 2.2 The second shell tried to open with flag O_RDWR|O_SYNC, write the same buffer to the same file, write operation returned EAGAIN 2.3 The same operation on ext4 file system gives me a expected behavior the same as advisory lock expressed, successfully written with file content changed. I reviewed NFS 4.1 protocol(RFC 5661 page 185), the nfs server can determine whether byte range lock can be either mandatory or advisory, but I think 2.1 and 2.2 gives me some unexpected behavior as these two.. What’s your idea about this? Can you give me some tips to work this out? Looking forward for your reply. Thanks in advance! BTW, my linux kernel version is 4.15.0, linux release: ubuntu 16.04 from Azure marketplace, my nfs-common version is "nfs-common/xenial-updates,now 1:1.2.8-9ubuntu12.1 amd64" from ubuntu apt repo. Thanks, Gefei
