Commit f57e2416 authored by Eric Blake's avatar Eric Blake Committed by Paolo Bonzini
Browse files

nbd: Clean up ioctl handling of qemu-nbd -c 



The kernel ioctl() interface into NBD is limited to 'unsigned long';
we MUST pass in input with that type (and not int or size_t, as
there may be platform ABIs where the wrong types promote incorrectly
through var-args).  Furthermore, on 32-bit platforms, the kernel
is limited to a maximum export size of 2T (our BLKSIZE of 512 times
a SIZE_BLOCKS constrained by 32 bit unsigned long).

Signed-off-by: default avatarEric Blake <eblake@redhat.com>
Message-Id: <1463006384-7734-8-git-send-email-eblake@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 98494e3b

nbd/client.c

+15 −5
Original line number Diff line number Diff line
@@ -593,9 +593,15 @@ fail: 
#ifdef __linux__

int nbd_init(int fd, QIOChannelSocket *sioc, uint32_t flags, off_t size)

{

    unsigned long sectors = size / BDRV_SECTOR_SIZE;

    if (size / BDRV_SECTOR_SIZE != sectors) {

        LOG("Export size %lld too large for 32-bit kernel", (long long) size);

        return -E2BIG;

    }



    TRACE("Setting NBD socket");



    if (ioctl(fd, NBD_SET_SOCK, sioc->fd) < 0) {

    if (ioctl(fd, NBD_SET_SOCK, (unsigned long) sioc->fd) < 0) {

        int serrno = errno;

        LOG("Failed to set NBD socket");

        return -serrno;
@@ -603,21 +609,25 @@ int nbd_init(int fd, QIOChannelSocket *sioc, uint32_t flags, off_t size) 


    TRACE("Setting block size to %lu", (unsigned long)BDRV_SECTOR_SIZE);



    if (ioctl(fd, NBD_SET_BLKSIZE, (size_t)BDRV_SECTOR_SIZE) < 0) {

    if (ioctl(fd, NBD_SET_BLKSIZE, (unsigned long)BDRV_SECTOR_SIZE) < 0) {

        int serrno = errno;

        LOG("Failed setting NBD block size");

        return -serrno;

    }



    TRACE("Setting size to %zd block(s)", (size_t)(size / BDRV_SECTOR_SIZE));

    TRACE("Setting size to %lu block(s)", sectors);

    if (size % BDRV_SECTOR_SIZE) {

        TRACE("Ignoring trailing %d bytes of export",

              (int) (size % BDRV_SECTOR_SIZE));

    }



    if (ioctl(fd, NBD_SET_SIZE_BLOCKS, (size_t)(size / BDRV_SECTOR_SIZE)) < 0) {

    if (ioctl(fd, NBD_SET_SIZE_BLOCKS, sectors) < 0) {

        int serrno = errno;

        LOG("Failed setting size (in blocks)");

        return -serrno;

    }



    if (ioctl(fd, NBD_SET_FLAGS, flags) < 0) {

    if (ioctl(fd, NBD_SET_FLAGS, (unsigned long) flags) < 0) {

        if (errno == ENOTTY) {

            int read_only = (flags & NBD_FLAG_READ_ONLY) != 0;

            TRACE("Setting readonly attribute");