diff options
| author | Eric Blake <eblake@redhat.com> | 2016-10-14 13:33:04 -0500 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2016-11-02 09:28:55 +0100 |
| commit | b626b51a6721e53817155af720243f59072e424f (patch) | |
| tree | ad00a53ab79e04ddcc2d09fd21ade2640f3da955 /include/block/nbd.h | |
| parent | b1a75b3348010820cc324943f09e090ea1fc524f (diff) | |
| download | qemu-b626b51a6721e53817155af720243f59072e424f.zip | |
nbd: Treat flags vs. command type as separate fields
Current upstream NBD documents that requests have a 16-bit flags,
followed by a 16-bit type integer; although older versions mentioned
only a 32-bit field with masking to find flags. Since the protocol
is in network order (big-endian over the wire), the ABI is unchanged;
but dealing with the flags as a separate field rather than masking
will make it easier to add support for upcoming NBD extensions that
increase the number of both flags and commands.
Improve some comments in nbd.h based on the current upstream
NBD protocol (https://github.com/yoe/nbd/blob/master/doc/proto.md),
and touch some nearby code to keep checkpatch.pl happy.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1476469998-28592-3-git-send-email-eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'include/block/nbd.h')
| -rw-r--r-- | include/block/nbd.h | 18 |
1 files changed, 12 insertions, 6 deletions
diff --git a/include/block/nbd.h b/include/block/nbd.h index fd58390d5d..5fe2670fdb 100644 --- a/include/block/nbd.h +++ b/include/block/nbd.h @@ -1,4 +1,5 @@ /* + * Copyright (C) 2016 Red Hat, Inc. * Copyright (C) 2005 Anthony Liguori <anthony@codemonkey.ws> * * Network Block Device @@ -32,7 +33,8 @@ struct nbd_request { uint64_t handle; uint64_t from; uint32_t len; - uint32_t type; + uint16_t flags; + uint16_t type; }; struct nbd_reply { @@ -40,6 +42,8 @@ struct nbd_reply { uint32_t error; }; +/* Transmission (export) flags: sent from server to client during handshake, + but describe what will happen during transmission */ #define NBD_FLAG_HAS_FLAGS (1 << 0) /* Flags are there */ #define NBD_FLAG_READ_ONLY (1 << 1) /* Device is read-only */ #define NBD_FLAG_SEND_FLUSH (1 << 2) /* Send FLUSH */ @@ -47,10 +51,12 @@ struct nbd_reply { #define NBD_FLAG_ROTATIONAL (1 << 4) /* Use elevator algorithm - rotational media */ #define NBD_FLAG_SEND_TRIM (1 << 5) /* Send TRIM (discard) */ -/* New-style global flags. */ +/* New-style handshake (global) flags, sent from server to client, and + control what will happen during handshake phase. */ #define NBD_FLAG_FIXED_NEWSTYLE (1 << 0) /* Fixed newstyle protocol. */ -/* New-style client flags. */ +/* New-style client flags, sent from client to server to control what happens + during handshake phase. */ #define NBD_FLAG_C_FIXED_NEWSTYLE (1 << 0) /* Fixed newstyle protocol. */ /* Reply types. */ @@ -61,10 +67,10 @@ struct nbd_reply { #define NBD_REP_ERR_INVALID ((UINT32_C(1) << 31) | 3) /* Invalid length. */ #define NBD_REP_ERR_TLS_REQD ((UINT32_C(1) << 31) | 5) /* TLS required */ +/* Request flags, sent from client to server during transmission phase */ +#define NBD_CMD_FLAG_FUA (1 << 0) -#define NBD_CMD_MASK_COMMAND 0x0000ffff -#define NBD_CMD_FLAG_FUA (1 << 16) - +/* Supported request types */ enum { NBD_CMD_READ = 0, NBD_CMD_WRITE = 1, |