Can not write file , even the directory has permission to read/write

[johnwmail]

Description

Please take a look the screen, thank you.

Steps to reproduce

No response

runsc version

docker version (if using docker)

uname

No response

kubectl (if using Kubernetes)

repo state (if built from source)

No response

runsc debug logs (if available)

[EtiennePerot]

Do you observe the same behavior with similar permissions on a non-NFS mountpoint? I'm wondering if this is NFS-specific.

[johnwmail]

Do you observe the same behavior with similar permissions on a non-NFS mountpoint? I'm wondering if this is NFS-specific.

Yes, maybe NFS-specific.

1. /localdisk/fid work
2. /nfs/fid NOT WORK
3. /tmpfs/fid work

PS: runc runtime work for all above mount point

[ayushr2]

For NFS mounts, we set disable_file_handle_sharing mount option:

gvisor/runsc/cmd/gofer.go

Lines 744 to 750 in c238e15

	case unix.NFS_SUPER_MAGIC, unix.FUSE_SUPER_MAGIC:
	// The gofer client implements remote file handle sharing for performance.
	// However, remote filesystems like NFS and FUSE rely on close(2) syscall
	// for flushing file data to the server. Such handle sharing prevents the
	// application's close(2) syscall from being propagated to the host. Hence
	// disable file handle sharing, so remote files are flushed correctly.
	rv = append(rv, "disable_file_handle_sharing")

So it may have something to do with that option, in which gofer filesystem uses gofer.specialFileFD for regular files.