Re: [PATCH 1/2] 4.1.2 blktap2 cleanup fixes.

[Ian Campbell <ian.campbell@citrix.com>]

On Wed, 2012-11-07 at 02:06 +0000, Dr. Greg Wettstein wrote:
> ---------------------------------------------------------------------------
> Backport of the following patch from development:
> 
> # User Ian Campbell <[hidden email]>
> # Date 1309968705 -3600
> # Node ID e4781aedf817c5ab36f6f3077e44c43c566a2812
> # Parent 700d0f03d50aa6619d313c1ff6aea7fd429d28a7
> libxl: attempt to cleanup tapdisk processes on disk backend destroy.
> 
> This patch properly terminates the tapdisk2 process(es) started
> to service a virtual block device.
> 
> Signed-off-by: Greg Wettstein <greg@enjellic.com>

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>

> 
> diff -r 700d0f03d50a tools/blktap2/control/tap-ctl-list.c
> --- a/tools/blktap2/control/tap-ctl-list.c	Mon Oct 29 09:04:48 2012 +0100
> +++ b/tools/blktap2/control/tap-ctl-list.c	Tue Nov 06 19:52:48 2012 -0600
> @@ -506,17 +506,15 @@ out:
>  }
>  
>  int
> -tap_ctl_find_minor(const char *type, const char *path)
> +tap_ctl_find(const char *type, const char *path, tap_list_t *tap)
>  {
>  	tap_list_t **list, **_entry;
> -	int minor, err;
> +	int ret = -ENOENT, err;
>  
>  	err = tap_ctl_list(&list);
>  	if (err)
>  		return err;
>  
> -	minor = -1;
> -
>  	for (_entry = list; *_entry != NULL; ++_entry) {
>  		tap_list_t *entry  = *_entry;
>  
> @@ -526,11 +524,13 @@ tap_ctl_find_minor(const char *type, con
>  		if (path && (!entry->path || strcmp(entry->path, path)))
>  			continue;
>  
> -		minor = entry->minor;
> +		*tap = *entry;
> +		tap->type = tap->path = NULL;
> +		ret = 0;
>  		break;
>  	}
>  
>  	tap_ctl_free_list(list);
>  
> -	return minor >= 0 ? minor : -ENOENT;
> +	return ret;
>  }
> diff -r 700d0f03d50a tools/blktap2/control/tap-ctl.h
> --- a/tools/blktap2/control/tap-ctl.h	Mon Oct 29 09:04:48 2012 +0100
> +++ b/tools/blktap2/control/tap-ctl.h	Tue Nov 06 19:52:48 2012 -0600
> @@ -76,7 +76,7 @@ int tap_ctl_get_driver_id(const char *ha
>  
>  int tap_ctl_list(tap_list_t ***list);
>  void tap_ctl_free_list(tap_list_t **list);
> -int tap_ctl_find_minor(const char *type, const char *path);
> +int tap_ctl_find(const char *type, const char *path, tap_list_t *tap);
>  
>  int tap_ctl_allocate(int *minor, char **devname);
>  int tap_ctl_free(const int minor);
> diff -r 700d0f03d50a tools/libxl/libxl_blktap2.c
> --- a/tools/libxl/libxl_blktap2.c	Mon Oct 29 09:04:48 2012 +0100
> +++ b/tools/libxl/libxl_blktap2.c	Tue Nov 06 19:52:48 2012 -0600
> @@ -18,6 +18,8 @@
>  
>  #include "tap-ctl.h"
>  
> +#include <string.h>
> +
>  int libxl__blktap_enabled(libxl__gc *gc)
>  {
>      const char *msg;
> @@ -30,12 +32,13 @@ const char *libxl__blktap_devpath(libxl_
>  {
>      const char *type;
>      char *params, *devname = NULL;
> -    int minor, err;
> +    tap_list_t tap;
> +    int err;
>  
>      type = libxl__device_disk_string_of_format(format);
> -    minor = tap_ctl_find_minor(type, disk);
> -    if (minor >= 0) {
> -        devname = libxl__sprintf(gc, "/dev/xen/blktap-2/tapdev%d", minor);
> +    err = tap_ctl_find(type, disk, &tap);
> +    if (err == 0) {
> +        devname = libxl__sprintf(gc, "/dev/xen/blktap-2/tapdev%d", tap.minor);
>          if (devname)
>              return devname;
>      }
> @@ -49,3 +52,28 @@ const char *libxl__blktap_devpath(libxl_
>  
>      return NULL;
>  }
> +
> +
> +void libxl__device_destroy_tapdisk(libxl__gc *gc, char *be_path)
> +{
> +    char *path, *params, *type, *disk;
> +    int err;
> +    tap_list_t tap;
> +
> +    path = libxl__sprintf(gc, "%s/tapdisk-params", be_path);
> +    if (!path) return;
> +
> +    params = libxl__xs_read(gc, XBT_NULL, path);
> +    if (!params) return;
> +
> +    type = params;
> +    disk = strchr(params, ':');
> +    if (!disk) return;
> +
> +    *disk++ = '\0';
> +
> +    err = tap_ctl_find(type, disk, &tap);
> +    if (err < 0) return;
> +
> +    tap_ctl_destroy(tap.id, tap.minor);
> +}
> diff -r 700d0f03d50a tools/libxl/libxl_device.c
> --- a/tools/libxl/libxl_device.c	Mon Oct 29 09:04:48 2012 +0100
> +++ b/tools/libxl/libxl_device.c	Tue Nov 06 19:52:48 2012 -0600
> @@ -250,6 +250,7 @@ int libxl__device_destroy(libxl_ctx *ctx
>      if (!state)
>          goto out;
>      if (atoi(state) != 4) {
> +        libxl__device_destroy_tapdisk(&gc, be_path);
>          xs_rm(ctx->xsh, XBT_NULL, be_path);
>          goto out;
>      }
> @@ -368,6 +369,7 @@ int libxl__devices_destroy(libxl_ctx *ct
>              }
>          }
>      }
> +    libxl__device_destroy_tapdisk(&gc, be_path);
>  out:
>      libxl__free_all(&gc);
>      return 0;
> diff -r 700d0f03d50a tools/libxl/libxl_internal.h
> --- a/tools/libxl/libxl_internal.h	Mon Oct 29 09:04:48 2012 +0100
> +++ b/tools/libxl/libxl_internal.h	Tue Nov 06 19:52:48 2012 -0600
> @@ -314,6 +314,12 @@ _hidden const char *libxl__blktap_devpat
>                                   const char *disk,
>                                   libxl_disk_format format);
>  
> +/* libxl__device_destroy_tapdisk:
> + *   Destroys any tapdisk process associated with the backend represented
> + *   by be_path.
> + */
> +_hidden void libxl__device_destroy_tapdisk(libxl__gc *gc, char *be_path);
> +
>  _hidden char *libxl__uuid2string(libxl__gc *gc, const libxl_uuid uuid);
>  
>  struct libxl__xen_console_reader {
> diff -r 700d0f03d50a tools/libxl/libxl_noblktap2.c
> --- a/tools/libxl/libxl_noblktap2.c	Mon Oct 29 09:04:48 2012 +0100
> +++ b/tools/libxl/libxl_noblktap2.c	Tue Nov 06 19:52:48 2012 -0600
> @@ -27,3 +27,7 @@ const char *libxl__blktap_devpath(libxl_
>  {
>      return NULL;
>  }
> +
> +void libxl__device_destroy_tapdisk(libxl__gc *gc, char *be_path)
> +{
> +}
> ---------------------------------------------------------------------------
> 
> As always,
> Dr. G.W. Wettstein, Ph.D.   Enjellic Systems Development, LLC.
> 4206 N. 19th Ave.           Specializing in information infra-structure
> Fargo, ND  58102            development.
> PH: 701-281-1686
> FAX: 701-281-3949           EMAIL: greg@enjellic.com
> ------------------------------------------------------------------------------
> "Man, despite his artistic pretensions, his sophistication and many
>  accomplishments, owes the fact of his existence to a six-inch layer of
>  topsoil and the fact that it rains."
>                                 -- Anonymous writer on perspective.
>                                    GAUSSIAN quote.
> 
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