EIO for ioctl FS_IOC_GETFLAGS

[dbnicholson]

Not sure if this is expected behavior, a fuse-overlayfs issue or a fuse issue, but I get EIO when using lsattr after it calls ioctl with FS_IOC_GETFLAGS. From the caller:

$ lsattr -d d
lsattr: Input/output error While reading flags on d

Here's the strace output from fuse-overlayfs:

openat2(3, ".", {flags=O_RDONLY|O_NONBLOCK, resolve=RESOLVE_IN_ROOT}, 24) = 8
ioctl(8, FS_IOC_GETFLAGS, 0x7ffd6d1d1bc0) = 0
writev(5, [{iov_base="(\0\0\0\0\0\0\0\204\0\0\0\0\0\0\0", iov_len=16}, {iov_base="\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", iov_len=16}, {iov_base="\27\0\0\0\0\0\0\0", iov_len=8}], 3) = -1 EINVAL (Invalid argument)
dup(2)                                  = 9
fcntl(9, F_GETFL)                       = 0x80002 (flags O_RDWR|O_CLOEXEC)
fstat(9, {st_mode=S_IFCHR|0620, st_rdev=makedev(0x88, 0), ...}) = 0
write(9, "fuse: writing device: Invalid argument\n", 39fuse: writing device: Invalid argument
) = 39
close(9)                                = 0
close(8)                                = 0

What I don't get is the actual ioctl call succeeds, but then writev gets EINVAL writing to /dev/fuse. This is running unprivileged from the root user namespace, but I originally hit it in a podman container. This is with fuse-overlayfs 1.7.1, fuse 3.10.3 and linux 5.13.0.

[giuseppe]

opened a PR: #335