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Date: Wed, 23 Aug 2017 13:01:56 +0800
From: Fam Zheng <famz@redhat.com>
Message-ID: <20170823050156.GC21343@lemon>
References: <20170822131832.20191-1-pbonzini@redhat.com>
	<20170822131832.20191-10-pbonzini@redhat.com>
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In-Reply-To: <20170822131832.20191-10-pbonzini@redhat.com>
Subject: Re: [Qemu-devel] [PATCH 09/10] scsi: add multipath support to
 qemu-pr-helper
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org

On Tue, 08/22 15:18, Paolo Bonzini wrote:
> Proper support of persistent reservation for multipath devices requires
> communication with the multipath daemon, so that the reservation is
> registered and applied when a path comes up.  The device mapper
> utilities provide a library to do so; this patch makes qemu-pr-helper.c
> detect multipath devices and, when one is found, delegate the operation
> to libmpathpersist.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  Makefile              |   3 +
>  configure             |  57 ++++++++-
>  docs/pr-manager.rst   |  27 +++++
>  include/scsi/utils.h  |   6 +
>  scsi/qemu-pr-helper.c | 311 +++++++++++++++++++++++++++++++++++++++++++++++++-
>  scsi/utils.c          |  15 +++
>  6 files changed, 414 insertions(+), 5 deletions(-)
> 
> diff --git a/Makefile b/Makefile
> index bfd4f69ecd..f1acaad05b 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -388,6 +388,9 @@ fsdev/virtfs-proxy-helper$(EXESUF): fsdev/virtfs-proxy-helper.o fsdev/9p-marshal
>  fsdev/virtfs-proxy-helper$(EXESUF): LIBS += -lcap
>  
>  scsi/qemu-pr-helper$(EXESUF): scsi/qemu-pr-helper.o scsi/utils.o $(crypto-obj-y) $(io-obj-y) $(qom-obj-y) $(COMMON_LDADDS)
> +ifdef CONFIG_MPATH
> +scsi/qemu-pr-helper$(EXESUF): LIBS += -ludev -lmultipath -lmpathpersist
> +endif
>  
>  qemu-img-cmds.h: $(SRC_PATH)/qemu-img-cmds.hx $(SRC_PATH)/scripts/hxtool
>  	$(call quiet-command,sh $(SRC_PATH)/scripts/hxtool -h < $< > $@,"GEN","$@")
> diff --git a/configure b/configure
> index 772aff18d6..d3c9371f7c 100755
> --- a/configure
> +++ b/configure
> @@ -286,6 +286,7 @@ pixman=""
>  sdl=""
>  sdlabi=""
>  virtfs=""
> +mpath=""

Whole patch: s/\<mpath\>/pr-helper/ ?

>  vnc="yes"
>  sparse="no"
>  vde=""
> @@ -948,6 +949,10 @@ for opt do
>    ;;
>    --enable-virtfs) virtfs="yes"
>    ;;
> +  --disable-mpath) mpath="no"
> +  ;;
> +  --enable-mpath) mpath="yes"
> +  ;;
>    --disable-vnc) vnc="no"
>    ;;
>    --enable-vnc) vnc="yes"
> @@ -1491,6 +1496,7 @@ disabled with --disable-FEATURE, default is enabled if available:
>    vnc-png         PNG compression for VNC server
>    cocoa           Cocoa UI (Mac OS X only)
>    virtfs          VirtFS
> +  mpath           Multipath persistent reservation passthrough
>    xen             xen backend driver support
>    xen-pci-passthrough
>    brlapi          BrlAPI (Braile)
> @@ -3336,6 +3342,29 @@ else
>  fi
>  
>  ##########################################
> +# libmpathpersist probe
> +
> +if test "$mpath" != "no" ; then
> +  cat > $TMPC <<EOF
> +#include <libudev.h>
> +#include <mpath_persist.h>
> +unsigned mpath_mx_alloc_len = 1024;
> +int logsink;
> +int main(void) {
> +    struct udev *udev = udev_new();
> +    mpath_lib_init(udev);
> +}
> +EOF
> +  if compile_prog "" "-ludev -lmultipath -lmpathpersist" ; then
> +    mpathpersist=yes
> +  else
> +    mpathpersist=no
> +  fi
> +else
> +  mpathpersist=no
> +fi
> +
> +##########################################
>  # libcap probe
>  
>  if test "$cap" != "no" ; then
> @@ -5070,16 +5099,34 @@ if test "$want_tools" = "yes" ; then
>    fi
>  fi
>  if test "$softmmu" = yes ; then
> -  if test "$virtfs" != no ; then
> -    if test "$cap" = yes && test "$linux" = yes && test "$attr" = yes ; then
> +  if test "$linux" = yes; then
> +    if test "$virtfs" != no && test "$cap" = yes && test "$attr" = yes ; then
>        virtfs=yes
>        tools="$tools fsdev/virtfs-proxy-helper\$(EXESUF)"
>      else
>        if test "$virtfs" = yes; then
> -        error_exit "VirtFS is supported only on Linux and requires libcap devel and libattr devel"
> +        error_exit "VirtFS requires libcap devel and libattr devel"
>        fi
>        virtfs=no
>      fi
> +    if test "$mpath" != no && test "$mpathpersist" = yes ; then
> +      mpath=yes
> +      tools="$tools mpath/qemu-mpath-helper\$(EXESUF)"

scsi/qemu-pr-helper?

> +    else
> +      if test "$mpath" = yes; then
> +        error_exit "Multipath requires libmpathpersist devel"
> +      fi
> +      mpath=no
> +    fi
> +  else
> +    if test "$virtfs" = yes; then
> +      error_exit "VirtFS is supported only on Linux"
> +    fi
> +    virtfs=no
> +    if test "$mpath" = yes; then
> +      error_exit "Multipath is supported only on Linux"
> +    fi
> +    mpath=no
>    fi
>  fi
>  
> @@ -5326,6 +5373,7 @@ echo "Audio drivers     $audio_drv_list"
>  echo "Block whitelist (rw) $block_drv_rw_whitelist"
>  echo "Block whitelist (ro) $block_drv_ro_whitelist"
>  echo "VirtFS support    $virtfs"
> +echo "Multipath support $mpath"
>  echo "VNC support       $vnc"
>  if test "$vnc" = "yes" ; then
>      echo "VNC SASL support  $vnc_sasl"
> @@ -5773,6 +5821,9 @@ fi
>  if test "$virtfs" = "yes" ; then
>    echo "CONFIG_VIRTFS=y" >> $config_host_mak
>  fi
> +if test "$mpath" = "yes" ; then
> +  echo "CONFIG_MPATH=y" >> $config_host_mak
> +fi
>  if test "$vhost_scsi" = "yes" ; then
>    echo "CONFIG_VHOST_SCSI=y" >> $config_host_mak
>  fi

Fam