On Mon, 2016-01-18 at 13:24 -0500, Anne Mulhern wrote: > Thanks. > > Are there any guidelines or rules available regarding the use > of namespaces in sysfs that you can refer me to? I don't believe there are any, sorry. What I'm describing isn't really true namespacing, it's using namespace techniques to avoid potential unique name clashes. There's nothing formally documented about this in sysfs-rules.txt; it is simply the type of thing that often gets done to avoid unique name issues in filesystems. James > I maintain pyudev, which is a python wrapper around libudev > with some added conveniences, and I'm wondering if there is > some functionality around namespaces that could be usefully > added. > > - mulhern > > ----- Original Message ----- > > From: "James Bottomley" <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> > > To: "Anne Mulhern" <amulhern@xxxxxxxxxx> > > Cc: linux-scsi@xxxxxxxxxxxxxxx > > Sent: Friday, January 15, 2016 2:38:05 PM > > Subject: Re: /sys/.../enclosure_device:<something> ? > > > > On Fri, 2016-01-15 at 14:32 -0500, Anne Mulhern wrote: > > > > > > > > > > > > ----- Original Message ----- > > > > From: "James Bottomley" <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> > > > > To: "Anne Mulhern" <amulhern@xxxxxxxxxx> > > > > Cc: linux-scsi@xxxxxxxxxxxxxxx > > > > Sent: Wednesday, January 13, 2016 3:30:07 PM > > > > Subject: Re: /sys/.../enclosure_device:<something> ? > > > > > > > > On Wed, 2016-01-13 at 15:15 -0500, Anne Mulhern wrote: > > > > > > > > > > > > > > > > > > > > ----- Original Message ----- > > > > > > From: "James Bottomley" < > > > > > > James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> > > > > > > To: "Anne Mulhern" <amulhern@xxxxxxxxxx>, > > > > > > linux-scsi@xxxxxxxxxxxxxxx > > > > > > Sent: Wednesday, January 13, 2016 2:15:05 PM > > > > > > Subject: Re: /sys/.../enclosure_device:<something> ? > > > > > > > > > > > > On Wed, 2016-01-13 at 11:28 -0500, Anne Mulhern wrote: > > > > > > > Hi! > > > > > > > > > > > > > > I'm looking for the most precise information available > > > > > > > about > > > > > > > the > > > > > > > meaning of <something> > > > > > > > and from what it is derived. I'm also interested in what > > > > > > > the > > > > > > > values > > > > > > > in the files in that directory > > > > > > > may mean. Could somebody point me there? > > > > > > > > > > > > It's in drivers/misc/enclosure.c:enclosure_link_name() > > > > > > > > > > > > > > > > Thanks. I will do my best with that. > > > > > > > > > > > > Also, how can there be more than one enclosure_device > > > > > > > subdirectory > > > > > > > for the same device, > > > > > > > or, alternatively, why isn't <something> stored in a file > > > > > > > in > > > > > > > the > > > > > > > more > > > > > > > regularly named directory > > > > > > > /sys/.../enclosure_device? > > > > > > > > > > > > I'm not sure I parse the question, but if you're asking how > > > > > > can > > > > > > a > > > > > > single enclosure bay appear to have more than one device, > > > > > > that's > > > > > > when > > > > > > there are multiple paths to the device. > > > > > > > > > > I'm afraid the word path is so overloaded...I'm assuming that > > > > > you > > > > > are talking about a multipathed environment, where two device > > > > > nodes, > > > > > say /dev/sdb, /dev/sdc correspond to the same disk, and are > > > > > hence > > > > > multipathed. Of course, in that case, it makes sense that > > > > > both > > > > > devices should share a bay. And that's what I observe. > > > > > > > > Yes, that's what I meant. > > > > > > > > > If I understand you correctly, then my question is actually > > > > > the > > > > > opposite. Why does it look as if the directories are set up > > > > > so > > > > > that > > > > > there can be multiple bays for a single device...i.e., the > > > > > directory > > > > > naming scheme allows me to specify an arbitrary number of > > > > > bays > > > > > for > > > > > /dev/sdb. It seems like there should never be more than one? > > > > > > > > There is only one bay per device since a physical disk can't be > > > > in > > > > more > > > > than one bay at once. Why do you think it was set up to allow > > > > >1? > > > > > > > > > > Purely because the naming scheme for the directory, > > > 'enclosure_device:<identifier>' supports more than 1. > > > > > > This directory pops up in the directory of the parent device > > > representing > > > a block device, and should represent just the bay for that > > > device, > > > AFAIU. > > > > > > The most compelling reason for this naming scheme to support more > > > than 1 > > > subdirectory is if it is necessary, i.e., there are more than one > > > possible. > > > > > > That might be true if my understanding of the block device's > > > parent > > > device's > > > meaning is incorrect or if something else doesn't mean what I > > > think > > > it means. > > > > The enclosure_device: is a namespace prefix. It's sysfs, so we > > can't > > have two files of the same name and <identifier> is supplied by > > page 7 > > of the enclosure device ... it could be anything. The only way to > > ensure we don't have a clash is to use a namespace prefix. > > > > James > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux > > -scsi" in > > the body of a message to majordomo@xxxxxxxxxxxxxxx > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-scsi" > in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
