qemu/block/nbd-client.h
Eric Blake 7423f41782 nbd: Limit nbdflags to 16 bits
Rather than asserting that nbdflags is within range, just give
it the correct type to begin with :)  nbdflags corresponds to
the per-export portion of NBD Protocol "transmission flags", which
is 16 bits in response to NBD_OPT_EXPORT_NAME and NBD_OPT_GO.

Furthermore, upstream NBD has never passed the global flags to
the kernel via ioctl(NBD_SET_FLAGS) (the ioctl was first
introduced in NBD 2.9.22; then a latent bug in NBD 3.1 actually
tried to OR the global flags with the transmission flags, with
the disaster that the addition of NBD_FLAG_NO_ZEROES in 3.9
caused all earlier NBD 3.x clients to treat every export as
read-only; NBD 3.10 and later intentionally clip things to 16
bits to pass only transmission flags).  Qemu should follow suit,
since the current two global flags (NBD_FLAG_FIXED_NEWSTYLE
and NBD_FLAG_NO_ZEROES) have no impact on the kernel's behavior
during transmission.

CC: qemu-stable@nongnu.org
Signed-off-by: Eric Blake <eblake@redhat.com>

Message-Id: <1469129688-22848-3-git-send-email-eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-08-03 18:44:56 +02:00

59 lines
1.7 KiB
C

#ifndef NBD_CLIENT_H
#define NBD_CLIENT_H
#include "qemu-common.h"
#include "block/nbd.h"
#include "block/block_int.h"
#include "io/channel-socket.h"
/* #define DEBUG_NBD */
#if defined(DEBUG_NBD)
#define logout(fmt, ...) \
fprintf(stderr, "nbd\t%-24s" fmt, __func__, ##__VA_ARGS__)
#else
#define logout(fmt, ...) ((void)0)
#endif
#define MAX_NBD_REQUESTS 16
typedef struct NbdClientSession {
QIOChannelSocket *sioc; /* The master data channel */
QIOChannel *ioc; /* The current I/O channel which may differ (eg TLS) */
uint16_t nbdflags;
off_t size;
CoMutex send_mutex;
CoMutex free_sema;
Coroutine *send_coroutine;
int in_flight;
Coroutine *recv_coroutine[MAX_NBD_REQUESTS];
struct nbd_reply reply;
bool is_unix;
} NbdClientSession;
NbdClientSession *nbd_get_client_session(BlockDriverState *bs);
int nbd_client_init(BlockDriverState *bs,
QIOChannelSocket *sock,
const char *export_name,
QCryptoTLSCreds *tlscreds,
const char *hostname,
Error **errp);
void nbd_client_close(BlockDriverState *bs);
int nbd_client_co_pdiscard(BlockDriverState *bs, int64_t offset, int count);
int nbd_client_co_flush(BlockDriverState *bs);
int nbd_client_co_pwritev(BlockDriverState *bs, uint64_t offset,
uint64_t bytes, QEMUIOVector *qiov, int flags);
int nbd_client_co_preadv(BlockDriverState *bs, uint64_t offset,
uint64_t bytes, QEMUIOVector *qiov, int flags);
void nbd_client_detach_aio_context(BlockDriverState *bs);
void nbd_client_attach_aio_context(BlockDriverState *bs,
AioContext *new_context);
#endif /* NBD_CLIENT_H */