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https://github.com/libguestfs/libguestfs.git
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27355c9b0b
When you call guestfs_disk_create on a block device with format=raw then it will try to discard the blocks on the device.
129 lines
2.9 KiB
C
129 lines
2.9 KiB
C
/* libguestfs - the guestfsd daemon
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* Copyright (C) 2014 Red Hat Inc.
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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
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include <config.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdint.h>
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#include <inttypes.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <sys/ioctl.h>
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#ifdef HAVE_LINUX_FS_H
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#include <linux/fs.h>
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#endif
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#include "daemon.h"
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#include "actions.h"
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#include "optgroups.h"
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/* http://rwmj.wordpress.com/2014/03/11/blkdiscard-blkzeroout-blkdiscardzeroes-blksecdiscard/ */
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#ifdef BLKDISCARD
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int
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optgroup_blkdiscard_available (void)
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{
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return 1;
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}
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int
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do_blkdiscard (const char *device)
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{
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/* XXX We could read /sys/block/<device>/queue/discard_* in order to
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* determine if discard is supported and the largest request size we
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* are allowed to make. However:
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*
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* (1) Mapping the device name to /sys/block/<device> is quite hard
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* (cf. the lv_canonical function in daemon/lvm.c)
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*
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* (2) We don't really need to do this in modern libguestfs since
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* we're very likely to be using virtio-scsi, which supports
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* arbitrary block discards.
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*
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* Let's wait to see if it causes a problem in real world
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* situations.
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*/
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uint64_t range[2];
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int64_t size;
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int fd;
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size = do_blockdev_getsize64 (device);
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if (size == -1)
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return -1;
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range[0] = 0;
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range[1] = (uint64_t) size;
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fd = open (device, O_WRONLY|O_CLOEXEC);
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if (fd == -1) {
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reply_with_perror ("open: %s", device);
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return -1;
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}
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if (ioctl (fd, BLKDISCARD, range) == -1) {
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reply_with_perror ("ioctl: %s: BLKDISCARD", device);
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close (fd);
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return -1;
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}
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close (fd);
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return 0;
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}
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#else /* !BLKDISCARD */
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OPTGROUP_BLKDISCARD_NOT_AVAILABLE
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#endif
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#ifdef BLKDISCARDZEROES
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int
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optgroup_blkdiscardzeroes_available (void)
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{
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return 1;
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}
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int
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do_blkdiscardzeroes (const char *device)
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{
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int fd;
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unsigned int arg;
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fd = open (device, O_RDONLY|O_CLOEXEC);
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if (fd == -1) {
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reply_with_perror ("open: %s", device);
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return -1;
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}
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if (ioctl (fd, BLKDISCARDZEROES, &arg) == -1) {
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reply_with_perror ("ioctl: %s: BLKDISCARDZEROES", device);
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close (fd);
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return -1;
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}
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close (fd);
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return arg != 0;
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}
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#else /* !BLKDISCARDZEROES */
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OPTGROUP_BLKDISCARDZEROES_NOT_AVAILABLE
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#endif
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