[Xen-changelog] [xen-4.2-testing] xend/pvscsi: update sysfs parser for Linux 3.0

[Xen patchbot-4.2-testing <patchbot@xxxxxxx>]

# HG changeset patch
# User Olaf Hering <olaf@xxxxxxxxx>
# Date 1352829657 0
# Node ID 839e5d95d483586dac5073cb59f845910588b000
# Parent  b8916af165b9e900af428acc9332355144303578
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.

Signed-off-by: Olaf Hering <olaf@xxxxxxxxx>
Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
Committed-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

xen-unstable changeset: 26010:cff10030c6ea
Backport-requested-by: Olaf Hering <olaf@xxxxxxxxx>
Committed-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
---


diff -r b8916af165b9 -r 839e5d95d483 tools/python/xen/util/vscsi_util.py
--- a/tools/python/xen/util/vscsi_util.py       Tue Nov 13 18:00:51 2012 +0000
+++ b/tools/python/xen/util/vscsi_util.py       Tue Nov 13 18:00:57 2012 +0000
@@ -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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