235 lines
6.1 KiB
C
235 lines
6.1 KiB
C
/*
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* buse - block-device userspace extensions
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* Copyright (C) 2013 Adam Cozzette
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include <assert.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <linux/types.h>
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#include <netinet/in.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/ioctl.h>
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#include <sys/socket.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include "buse.h"
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/*
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* These helper functions were taken from cliserv.h in the nbd distribution.
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*/
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#ifdef WORDS_BIGENDIAN
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u_int64_t ntohll(u_int64_t a) {
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return a;
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}
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#else
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u_int64_t ntohll(u_int64_t a) {
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u_int32_t lo = a & 0xffffffff;
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u_int32_t hi = a >> 32U;
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lo = ntohl(lo);
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hi = ntohl(hi);
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return ((u_int64_t) lo) << 32U | hi;
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}
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#endif
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#define htonll ntohll
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static int read_all(int fd, char* buf, size_t count)
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{
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int bytes_read;
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while (count > 0) {
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bytes_read = read(fd, buf, count);
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assert(bytes_read > 0);
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buf += bytes_read;
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count -= bytes_read;
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}
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assert(count == 0);
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return 0;
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}
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static int write_all(int fd, char* buf, size_t count)
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{
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int bytes_written;
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while (count > 0) {
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bytes_written = write(fd, buf, count);
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assert(bytes_written > 0);
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buf += bytes_written;
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count -= bytes_written;
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}
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assert(count == 0);
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return 0;
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}
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int buse_main(const char* dev_file, const struct buse_operations *aop, void *userdata)
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{
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int sp[2];
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int nbd, sk, err, tmp_fd;
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u_int64_t from;
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u_int32_t len;
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ssize_t bytes_read;
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struct nbd_request request;
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struct nbd_reply reply;
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void *chunk;
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err = socketpair(AF_UNIX, SOCK_STREAM, 0, sp);
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assert(!err);
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nbd = open(dev_file, O_RDWR);
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if (nbd == -1) {
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fprintf(stderr,
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"Failed to open `%s': %s\n"
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"Is kernel module `nbd' is loaded and you have permissions "
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"to access the device?\n", dev_file, strerror(errno));
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return 1;
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}
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if (aop->blksize) {
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err = ioctl(nbd, NBD_SET_BLKSIZE, aop->blksize);
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assert(err != -1);
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}
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if (aop->size) {
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err = ioctl(nbd, NBD_SET_SIZE, aop->size);
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assert(err != -1);
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}
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if (aop->size_blocks) {
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err = ioctl(nbd, NBD_SET_SIZE_BLOCKS, aop->size_blocks);
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assert(err != -1);
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}
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err = ioctl(nbd, NBD_CLEAR_SOCK);
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assert(err != -1);
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if (!fork()) {
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/* The child needs to continue setting things up. */
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close(sp[0]);
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sk = sp[1];
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if(ioctl(nbd, NBD_SET_SOCK, sk) == -1){
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fprintf(stderr, "ioctl(nbd, NBD_SET_SOCK, sk) failed.[%s]\n", strerror(errno));
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}
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#if defined NBD_SET_FLAGS && defined NBD_FLAG_SEND_TRIM
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else if(ioctl(nbd, NBD_SET_FLAGS, NBD_FLAG_SEND_TRIM) == -1){
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fprintf(stderr, "ioctl(nbd, NBD_SET_FLAGS, NBD_FLAG_SEND_TRIM) failed.[%s]\n", strerror(errno));
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}
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#endif
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else{
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err = ioctl(nbd, NBD_DO_IT);
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fprintf(stderr, "nbd device terminated with code %d\n", err);
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if (err == -1)
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fprintf(stderr, "%s\n", strerror(errno));
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}
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ioctl(nbd, NBD_CLEAR_QUE);
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ioctl(nbd, NBD_CLEAR_SOCK);
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exit(0);
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}
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/* The parent opens the device file at least once, to make sure the
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* partition table is updated. Then it closes it and starts serving up
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* requests. */
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tmp_fd = open(dev_file, O_RDONLY);
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assert(tmp_fd != -1);
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close(tmp_fd);
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close(sp[1]);
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sk = sp[0];
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reply.magic = htonl(NBD_REPLY_MAGIC);
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reply.error = htonl(0);
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while ((bytes_read = read(sk, &request, sizeof(request))) > 0) {
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assert(bytes_read == sizeof(request));
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memcpy(reply.handle, request.handle, sizeof(reply.handle));
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reply.error = htonl(0);
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len = ntohl(request.len);
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from = ntohll(request.from);
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assert(request.magic == htonl(NBD_REQUEST_MAGIC));
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switch(ntohl(request.type)) {
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/* I may at some point need to deal with the the fact that the
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* official nbd server has a maximum buffer size, and divides up
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* oversized requests into multiple pieces. This applies to reads
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* and writes.
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*/
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case NBD_CMD_READ:
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fprintf(stderr, "Request for read of size %d\n", len);
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/* Fill with zero in case actual read is not implemented */
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chunk = malloc(len);
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if (aop->read) {
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reply.error = aop->read(chunk, len, from, userdata);
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} else {
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/* If user not specified read operation, return EPERM error */
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reply.error = htonl(EPERM);
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}
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write_all(sk, (char*)&reply, sizeof(struct nbd_reply));
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write_all(sk, (char*)chunk, len);
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free(chunk);
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break;
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case NBD_CMD_WRITE:
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fprintf(stderr, "Request for write of size %d\n", len);
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chunk = malloc(len);
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read_all(sk, chunk, len);
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if (aop->write) {
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reply.error = aop->write(chunk, len, from, userdata);
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} else {
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/* If user not specified write operation, return EPERM error */
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reply.error = htonl(EPERM);
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}
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free(chunk);
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write_all(sk, (char*)&reply, sizeof(struct nbd_reply));
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break;
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case NBD_CMD_DISC:
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/* Handle a disconnect request. */
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if (aop->disc) {
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aop->disc(userdata);
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}
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return 0;
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#ifdef NBD_FLAG_SEND_FLUSH
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case NBD_CMD_FLUSH:
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if (aop->flush) {
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reply.error = aop->flush(userdata);
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}
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write_all(sk, (char*)&reply, sizeof(struct nbd_reply));
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break;
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#endif
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#ifdef NBD_FLAG_SEND_TRIM
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case NBD_CMD_TRIM:
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if (aop->trim) {
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reply.error = aop->trim(from, len, userdata);
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}
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write_all(sk, (char*)&reply, sizeof(struct nbd_reply));
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break;
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#endif
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default:
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assert(0);
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}
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}
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if (bytes_read == -1)
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fprintf(stderr, "%s\n", strerror(errno));
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return 0;
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}
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