Re: [Xen-devel] [PATCH 3 of 3] xend/pvscsi: update sysfs parser for Linux 3.0

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Thu, 2012-08-23 at 19:24 +0100, Olaf Hering wrote:
> # HG changeset patch
> # User Olaf Hering <olaf@xxxxxxxxx>
> # Date 1345743331 -7200
> # Node ID 482b9db173f2ceefed06346bec9e6d8cef9704fe
> # Parent  2b9992aea26cfebc2dda56d1a97a35dc3a5c8ce8
> xend/pvscsi: update sysfs parser for Linux 3.0
> 
> The sysfs parser for /sys/bus/scsi/devices understands only the layout
> of kernel version 2.6.16. This looks as follows:
> 
> /sys/bus/scsi/devices/1:0:0:0/block:sda is a symlink to /sys/block/sda/
> /sys/bus/scsi/devices/1:0:0:0/scsi_generic:sg1 is a symlink to 
> /sys/class/scsi_generic/sg1
> 
> Both directories contain a 'dev' file with the major:minor information.
> This patch updates the used regex strings to match also the colon to
> make it more robust against possible future changes.
> 
> 
> In kernel version 3.0 the layout changed:
> /sys/bus/scsi/devices/ contains now additional symlinks to directories
> such as host1 and target1:0:0. This patch ignores these as they do not
> point to the desired scsi devices. They just clutter the devices array.
> 
> The directory layout in '1:0:0:0' changed as well, the 'type:name'
> notation was replaced with 'type/name' directories:
> 
> /sys/bus/scsi/devices/1:0:0:0/block/sda/
> /sys/bus/scsi/devices/1:0:0:0/scsi_generic/sg1/
> 
> Both directories contain a 'dev' file with the major:minor information.
> This patch adds additional code to walk the subdir to find the 'dev'
> file to make sure the given subdirectory is really the kernel name.
> 
> 
> In addition this patch makes sure devname is not None.

Did you test this with both pre- and post-3.0 kernels?

> 
> Signed-off-by: Olaf Hering <olaf@xxxxxxxxx>
> 
> diff -r 2b9992aea26c -r 482b9db173f2 tools/python/xen/util/vscsi_util.py
> --- a/tools/python/xen/util/vscsi_util.py
> +++ b/tools/python/xen/util/vscsi_util.py
> @@ -130,20 +130,36 @@ def _vscsi_get_scsidevices_by_sysfs():
>  
>      for dirpath, dirnames, files in os.walk(sysfs_mnt + SYSFS_SCSI_PATH):
>          for hctl in dirnames:
> +            if len(hctl.split(':')) != 4:
> +                continue
>              paths = os.path.join(dirpath, hctl)
>              devname = None
>              sg = None
>              scsi_id = None
>              for f in os.listdir(paths):
>                  realpath = os.path.realpath(os.path.join(paths, f))
> -                if  re.match('^block', f) or \
> -                    re.match('^tape', f) or \
> -                    re.match('^scsi_changer', f) or \
> -                    re.match('^onstream_tape', f):
> +                if  re.match('^block:', f) or \
> +                    re.match('^tape:', f) or \
> +                    re.match('^scsi_changer:', f) or \
> +                    re.match('^onstream_tape:', f):
>                      devname = os.path.basename(realpath)
> +                elif f == "block" or \
> +                     f == "tape" or \
> +                     f == "scsi_changer" or \
> +                     f == "onstream_tape":
> +                    for dir in os.listdir(os.path.join(paths, f)):
> +                        if os.path.exists(os.path.join(paths, f, dir, 
> "dev")):
> +                            devname = os.path.basename(dir)
>  
> -                if re.match('^scsi_generic', f):
> +                if re.match('^scsi_generic:', f):
>                      sg = os.path.basename(realpath)
> +                elif f == "scsi_generic":
> +                    for dir in os.listdir(os.path.join(paths, f)):
> +                        if os.path.exists(os.path.join(paths, f, dir, 
> "dev")):
> +                            sg = os.path.basename(dir)
> +                if sg:
> +                    if devname is None:
> +                        devname = sg
>                      scsi_id = _vscsi_get_scsiid(sg)
>              devices.append([hctl, devname, sg, scsi_id])
>  
> 
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