Bug#365363: multipath fails when cheap USB disk present

[Michael Shuey]

Package: multipath-tools
Version: 0.4.7-1

The multipath tool dies (exit code is 1) whenever I have a particular cheap 
USB drive plugged in.  Digging a bit with strace shows:

<snip>
open("/sys/block/sdx/dev", O_RDONLY)    = 26
read(26, "65:112\n", 4096)              = 7
close(26)                               = 0
stat64("/sys/block/sdx/size", {st_mode=S_IFREG|0444, st_size=4096, ...}) = 0
open("/sys/block/sdx/size", O_RDONLY)   = 26
read(26, "160086528\n", 4096)           = 10
close(26)                               = 0
stat64("/sys/block/sdx/device/vendor", {st_mode=S_IFREG|0444, 
st_size=4096, ...}) = 0
open("/sys/block/sdx/device/vendor", O_RDONLY) = 26
read(26, "Maxtor 4\n", 4096)            = 9
close(26)                               = 0
stat64("/sys/block/sdx/device/model", {st_mode=S_IFREG|0444, 
st_size=4096, ...}) = 0
open("/sys/block/sdx/device/model", O_RDONLY) = 26
read(26, "D080H4          \n", 4096)    = 17
close(26)                               = 0
stat64("/sys/block/sdx/device/rev", {st_mode=S_IFREG|0444, 
st_size=4096, ...}) = 0
open("/sys/block/sdx/device/rev", O_RDONLY) = 26
read(26, "\n", 4096)                    = 1
close(26)                               = 0
close(4)                                = 0
<snip>

Sure enough, /dev/sdx is a cheapo USB disk enclose, and sysfs doesn't report 
a revision number for the drive.

If I unplug the USB disk, multipath works fine.  My guess is that either 
multipath itself, or maybe libsysfs, can't handle the existence of an 
empty /sys/block/sdx/device/rev.  If it matters, I'm using libsysfs2 
2.0.0-6.

-- 
Mike Shuey