> However, there is an assumption that file I/O will never block "indefinitely" -- unless something is severely broken, the kernel will always finish the operation in finite time probably measured in milliseconds at most. The same is not true of network communications, where you may be waiting for an event that never happens.
Doesn’t this statement assume all filesystems are local? If the filesystem is remote (NFS, CIFS/SMB, WebDAV or SSH via FUSE, etc), then regular file IO is the same thing as network communication - and an NFS server going down (or losing connectivity to it) no more counts as “severely broken” than the same scenario for any other network protocol/application/service.
A network filesystem is still expected to respond to reads and writes in a short finite time, assuming the network isn't broken.
For an arbitrary network protocol, the amount of time you wait for an event is arbitrary and application-dependent. Even if everything is working exactly as intended, you could be waiting indefinitely for an event.
The network could be completely fine but the NFS server could have crashed (and maybe the backups were faulty so it is never coming back). That’s absolutely no different than if the same thing happened to an SSH server or a HTTP server or any other network service. The assumption is no more valid for NFS than it is for an arbitrary protocol.
Doesn’t this statement assume all filesystems are local? If the filesystem is remote (NFS, CIFS/SMB, WebDAV or SSH via FUSE, etc), then regular file IO is the same thing as network communication - and an NFS server going down (or losing connectivity to it) no more counts as “severely broken” than the same scenario for any other network protocol/application/service.