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Add option for forcible unmounting dataset while receiving snapshot.
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Currently when the dataset is in use we can't receive snapshots.

    zfs send test/1@asd | zfs recv -FM test/2
    cannot unmount '/test/2': Device busy

This commits add option 'M' which attempts to forcibly unmount the
dataset.  Thanks to this we can enforce receiving snapshots in a
single step.

Note that this functionality is not supported on Linux because the
VFS will prevent active mounted filesystems from being unmounted,
even with the force option.  This is the intended VFS behavior.

Test cases were added to verify the expected behavior based on
the platform.

Discussed-with: Pawel Jakub Dawidek <pjd@FreeBSD.org>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Allan Jude <allanjude@freebsd.org>
External-issue: https://reviews.freebsd.org/D22306
Closes #9904
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oshogbo authored Mar 17, 2020
1 parent 80d98a8 commit a57d3d4
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Showing 7 changed files with 113 additions and 14 deletions.
9 changes: 6 additions & 3 deletions cmd/zfs/zfs_main.c
Original file line number Diff line number Diff line change
Expand Up @@ -298,10 +298,10 @@ get_usage(zfs_help_t idx)
case HELP_PROMOTE:
return (gettext("\tpromote <clone-filesystem>\n"));
case HELP_RECEIVE:
return (gettext("\treceive [-vnsFhu] "
return (gettext("\treceive [-vMnsFhu] "
"[-o <property>=<value>] ... [-x <property>] ...\n"
"\t <filesystem|volume|snapshot>\n"
"\treceive [-vnsFhu] [-o <property>=<value>] ... "
"\treceive [-vMnsFhu] [-o <property>=<value>] ... "
"[-x <property>] ... \n"
"\t [-d | -e] <filesystem>\n"
"\treceive -A <filesystem|volume>\n"));
Expand Down Expand Up @@ -4552,7 +4552,7 @@ zfs_do_receive(int argc, char **argv)
nomem();

/* check options */
while ((c = getopt(argc, argv, ":o:x:dehnuvFsA")) != -1) {
while ((c = getopt(argc, argv, ":o:x:dehMnuvFsA")) != -1) {
switch (c) {
case 'o':
if (!parseprop(props, optarg)) {
Expand Down Expand Up @@ -4587,6 +4587,9 @@ zfs_do_receive(int argc, char **argv)
case 'h':
flags.skipholds = B_TRUE;
break;
case 'M':
flags.forceunmount = B_TRUE;
break;
case 'n':
flags.dryrun = B_TRUE;
break;
Expand Down
3 changes: 3 additions & 0 deletions include/libzfs.h
Original file line number Diff line number Diff line change
Expand Up @@ -758,6 +758,9 @@ typedef struct recvflags {

/* mount the filesystem unless nomount is specified */
boolean_t domount;

/* force unmount while recv snapshot (private) */
boolean_t forceunmount;
} recvflags_t;

extern int zfs_receive(libzfs_handle_t *, const char *, nvlist_t *,
Expand Down
9 changes: 6 additions & 3 deletions lib/libzfs/libzfs_sendrecv.c
Original file line number Diff line number Diff line change
Expand Up @@ -4059,7 +4059,8 @@ zfs_receive_package(libzfs_handle_t *hdl, int fd, const char *destname,
ZFS_TYPE_FILESYSTEM);
if (zhp != NULL) {
clp = changelist_gather(zhp,
ZFS_PROP_MOUNTPOINT, 0, 0);
ZFS_PROP_MOUNTPOINT, 0,
flags->forceunmount ? MS_FORCE : 0);
zfs_close(zhp);
if (clp != NULL) {
softerr |=
Expand Down Expand Up @@ -4876,7 +4877,8 @@ zfs_receive_one(libzfs_handle_t *hdl, int infd, const char *tosnap,
if (!flags->dryrun && zhp->zfs_type == ZFS_TYPE_FILESYSTEM &&
stream_wantsnewfs) {
/* We can't do online recv in this case */
clp = changelist_gather(zhp, ZFS_PROP_NAME, 0, 0);
clp = changelist_gather(zhp, ZFS_PROP_NAME, 0,
flags->forceunmount ? MS_FORCE : 0);
if (clp == NULL) {
zfs_close(zhp);
err = -1;
Expand Down Expand Up @@ -5556,7 +5558,8 @@ zfs_receive(libzfs_handle_t *hdl, const char *tosnap, nvlist_t *props,
}

clp = changelist_gather(zhp, ZFS_PROP_MOUNTPOINT,
CL_GATHER_MOUNT_ALWAYS, 0);
CL_GATHER_MOUNT_ALWAYS,
flags->forceunmount ? MS_FORCE : 0);
zfs_close(zhp);
if (clp == NULL) {
err = -1;
Expand Down
13 changes: 8 additions & 5 deletions man/man8/zfs-receive.8
Original file line number Diff line number Diff line change
Expand Up @@ -30,7 +30,7 @@
.\" Copyright 2018 Nexenta Systems, Inc.
.\" Copyright 2019 Joyent, Inc.
.\"
.Dd June 30, 2019
.Dd February 16, 2020
.Dt ZFS-RECEIVE 8
.Os Linux
.Sh NAME
Expand All @@ -39,14 +39,14 @@
.Sh SYNOPSIS
.Nm
.Cm receive
.Op Fl Fhnsuv
.Op Fl FhMnsuv
.Op Fl o Sy origin Ns = Ns Ar snapshot
.Op Fl o Ar property Ns = Ns Ar value
.Op Fl x Ar property
.Ar filesystem Ns | Ns Ar volume Ns | Ns Ar snapshot
.Nm
.Cm receive
.Op Fl Fhnsuv
.Op Fl FhMnsuv
.Op Fl d Ns | Ns Fl e
.Op Fl o Sy origin Ns = Ns Ar snapshot
.Op Fl o Ar property Ns = Ns Ar value
Expand All @@ -61,7 +61,7 @@
.It Xo
.Nm
.Cm receive
.Op Fl Fhnsuv
.Op Fl FhMnsuv
.Op Fl o Sy origin Ns = Ns Ar snapshot
.Op Fl o Ar property Ns = Ns Ar value
.Op Fl x Ar property
Expand All @@ -70,7 +70,7 @@
.It Xo
.Nm
.Cm receive
.Op Fl Fhnsuv
.Op Fl FhMnsuv
.Op Fl d Ns | Ns Fl e
.Op Fl o Sy origin Ns = Ns Ar snapshot
.Op Fl o Ar property Ns = Ns Ar value
Expand Down Expand Up @@ -229,6 +229,9 @@ that element to determine the name of the target file system for the new
snapshot as described in the paragraph above.
.It Fl h
Skip the receive of holds. There is no effect if holds are not sent.
.It Fl M
Force an unmount of the file system while receiving a snapshot.
This option is not supported on Linux.
.It Fl n
Do not actually receive the stream.
This can be useful in conjunction with the
Expand Down
7 changes: 4 additions & 3 deletions tests/runfiles/common.run
Original file line number Diff line number Diff line change
Expand Up @@ -208,9 +208,10 @@ tests = ['zfs_receive_001_pos', 'zfs_receive_002_pos', 'zfs_receive_003_pos',
'zfs_receive_007_neg', 'zfs_receive_008_pos', 'zfs_receive_009_neg',
'zfs_receive_010_pos', 'zfs_receive_011_pos', 'zfs_receive_012_pos',
'zfs_receive_013_pos', 'zfs_receive_014_pos', 'zfs_receive_015_pos',
'receive-o-x_props_override', 'zfs_receive_from_encrypted',
'zfs_receive_to_encrypted', 'zfs_receive_raw',
'zfs_receive_raw_incremental', 'zfs_receive_-e', 'zfs_receive_raw_-d']
'zfs_receive_016_pos', 'receive-o-x_props_override',
'zfs_receive_from_encrypted', 'zfs_receive_to_encrypted',
'zfs_receive_raw', 'zfs_receive_raw_incremental', 'zfs_receive_-e',
'zfs_receive_raw_-d']
tags = ['functional', 'cli_root', 'zfs_receive']

[tests/functional/cli_root/zfs_rename]
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@ dist_pkgdata_SCRIPTS = \
zfs_receive_013_pos.ksh \
zfs_receive_014_pos.ksh \
zfs_receive_015_pos.ksh \
zfs_receive_016_pos.ksh \
receive-o-x_props_override.ksh \
zfs_receive_from_encrypted.ksh \
zfs_receive_to_encrypted.ksh \
Expand Down
Original file line number Diff line number Diff line change
@@ -0,0 +1,85 @@
#!/bin/ksh -p
#
# CDDL HEADER START
#
# This file and its contents are supplied under the terms of the
# Common Development and Distribution License ("CDDL"), version 1.0.
# You may only use this file in accordance with the terms of version
# 1.0 of the CDDL.
#
# A full copy of the text of the CDDL should have accompanied this
# source. A copy of the CDDL is also available via the Internet at
# http://www.illumos.org/license/CDDL.
#
# CDDL HEADER END
#
# Copyright (c) 2020 by Mariusz Zaborski <oshogbo@FreeBSD.org>.

#
# DESCRIPTION:
# Verify 'zfs recv' can forcibly unmount filesystem while receiving
# stream.
#
# STRATEGY:
# 1. Create snapshot of file system
# 2. Make a zfs filesystem mountpoint busy
# 3. Receive filesystem with force flag.
# 4. Verify that stream was received or failed on Linux.
#

. $STF_SUITE/tests/functional/cli_root/cli_common.kshlib

verify_runnable "both"

function cleanup
{
cd $curpath

for snap in $init_snap $rst_snap; do
snapexists $snap && \
destroy_snapshot $snap
done

datasetexists $rst_root && \
destroy_dataset $rst_root

for file in $full_bkup
do
[[ -e $file ]] && \
log_must rm -f $file
done

[[ -d $TESTDIR1 ]] && \
log_must rm -rf $TESTDIR1
}

log_assert "Verify 'zfs recv' can forcibly unmount busy filesystem."
log_onexit cleanup

curpath=`dirname $0`
init_snap=$TESTPOOL/$TESTFS@init_snap
full_bkup=$TEST_BASE_DIR/fullbkup.$$
rst_root=$TESTPOOL/rst_ctr
rst_snap=$rst_root@init_snap

log_note "Verify 'zfs recv' can forcible unmount busy filesystem."

# Preparation
log_must zfs create $rst_root
[[ ! -d $TESTDIR1 ]] && \
log_must mkdir -p $TESTDIR1
log_must zfs set mountpoint=$TESTDIR1 $rst_root

log_must zfs snapshot $init_snap
log_must eval "zfs send $init_snap > $full_bkup"

# Test
log_must cd $TESTDIR1
if is_linux; then
# Linux does not support it.
log_mustnot zfs receive -MF $rst_snap < $full_bkup
else
log_must zfs receive -MF $rst_snap < $full_bkup
fi

log_pass "The busy filesystem was unmounted or busy as expected."

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