[9fans] Explanation of binding from ftpfs

[9fans] Explanation of binding from ftpfs

[Brad Frank]

When I use ftpfs to mount a ftp site and then bind /n/ftp to another
location. All appears to work fine in /n/ftp and in the other
location. When I type ns, I can clearly see the pipe bind for ftpfs
mounted to /n/ftp. When I unmount /n/ftp I can type ls on /n/ftp and
not see anything there. But if I ls on the other location that I bound
to /n/ftp, it still can access the ftp server. How is the other
location able to do this, when I don't see any indication of a pipe
bind still listed in ns? I do see the ftpfs process running, though.

Re: [9fans] Explanation of binding from ftpfs

[Iruata Souza]

On Sat, Dec 6, 2008 at 6:44 PM, Brad Frank <brad.frank@gmail.com> wrote:
> When I use ftpfs to mount a ftp site and then bind /n/ftp to another
> location. All appears to work fine in /n/ftp and in the other
> location. When I type ns, I can clearly see the pipe bind for ftpfs
> mounted to /n/ftp. When I unmount /n/ftp I can type ls on /n/ftp and
> not see anything there. But if I ls on the other location that I bound
> to /n/ftp, it still can access the ftp server. How is the other
> location able to do this, when I don't see any indication of a pipe
> bind still listed in ns? I do see the ftpfs process running, though.
>
>

the bind shows here, like it should

cpu% ns | tail -3
mount -b '#s/rio.iru.323' /dev
mount -c '#|/data1' /n/ftp
cd /usr/iru
cpu% bind /n/ftp new
cpu% ns | tail -3
mount -c '#|/data1' /n/ftp
mount  '#|/data1' /usr/iru/new
cd /usr/iru
cpu% lc /n/ftp | tail -1
pub
cpu% unmount /n/ftp
cpu% ns | tail -3
mount -b '#s/rio.iru.323' /dev
mount  '#|/data1' /usr/iru/new
cd /usr/iru
cpu% lc /n/ftp
cpu% lc new | tail -1
pub
cpu% unmount new
cpu% ns | tail -3
mount  '#s/rio.iru.323' /mnt/wsys 1
mount -b '#s/rio.iru.323' /dev
cd /usr/iru


i may be mistaken here but it seems that unmount calls cclose which
calls decref and only if the mount is the last reference to the
server, it will be freed.
the behaviour seems ok here, then.

iru

Re: [9fans] Explanation of binding from ftpfs

[Brad Frank]

I forgot to mention when I bind /n/ftp I was really binding
/n/ftp/directory to another location.

On Sat, Dec 6, 2008 at 3:44 PM, Brad Frank <brad.frank@gmail.com> wrote:
> When I use ftpfs to mount a ftp site and then bind /n/ftp to another
> location. All appears to work fine in /n/ftp and in the other
> location. When I type ns, I can clearly see the pipe bind for ftpfs
> mounted to /n/ftp. When I unmount /n/ftp I can type ls on /n/ftp and
> not see anything there. But if I ls on the other location that I bound
> to /n/ftp, it still can access the ftp server. How is the other
> location able to do this, when I don't see any indication of a pipe
> bind still listed in ns? I do see the ftpfs process running, though.
>

Re: [9fans] Explanation of binding from ftpfs

[Iruata Souza]

On Sat, Dec 6, 2008 at 8:17 PM, Brad Frank <brad.frank@gmail.com> wrote:
> I forgot to mention when I bind /n/ftp I was really binding
> /n/ftp/directory to another location.
>

if I understand it correctly, the reference to the server is still
there even if you don't see /n/ftp anymore.

iru

Re: [9fans] Explanation of binding from ftpfs

[erik quanstrom]

>
> if I understand it correctly, the reference to the server is still
> there even if you don't see /n/ftp anymore.
>
> iru

yes, the reference is the other location.  there is no
heirarchy of mounts/binds.  tthere is no "master"
that if removed will remove the whole thing.
they are simply reference counted.

- erik

Re: [9fans] Explanation of binding from ftpfs

[Brad Frank]

I guess what confuses me when dealing with something like ftpfs, is
that it seems to behave differently than other types of binds.
Examples I've used in the past involve simple binds like this.
I create 4 directories, let's say dir1, dir2, dir3, dir4.
Inside dir1 and dir2 I have files.
I can then:
bind -b dir1 dir3
bind -b dir2 dir3
then I can
bind -b dir3 dir4

When I look at ns
I see not only a bind from dir3 to dir4,
But I also see binds from dir1 to dir4, and dir2 to dir4. The act of
binding dir3 to dir4 automatically seems to have created binds to dir1
to dir4, and dir2 to dir4.

So what I guess I was expecting to see from ns when using the ftpfs
scenario, was to see not only a pipe bind to /n/ftp. But Also a pipe
bind to my other location, since the other location was a bind to
/n/ftp.

On Sat, Dec 6, 2008 at 5:17 PM, Brad Frank <brad.frank@gmail.com> wrote:
> I forgot to mention when I bind /n/ftp I was really binding
> /n/ftp/directory to another location.
>
> On Sat, Dec 6, 2008 at 3:44 PM, Brad Frank <brad.frank@gmail.com> wrote:
>> When I use ftpfs to mount a ftp site and then bind /n/ftp to another
>> location. All appears to work fine in /n/ftp and in the other
>> location. When I type ns, I can clearly see the pipe bind for ftpfs
>> mounted to /n/ftp. When I unmount /n/ftp I can type ls on /n/ftp and
>> not see anything there. But if I ls on the other location that I bound
>> to /n/ftp, it still can access the ftp server. How is the other
>> location able to do this, when I don't see any indication of a pipe
>> bind still listed in ns? I do see the ftpfs process running, though.
>>
>

Re: [9fans] Explanation of binding from ftpfs

[Brad Frank]

oh yeah, it seems to do a pipe bind to the other location, only when
binding to the root. If I bind to /n/ftp/directory, it doesn't show
the pipe bind in ns.

On Sat, Dec 6, 2008 at 5:52 PM, Brad Frank <brad.frank@gmail.com> wrote:
> I guess what confuses me when dealing with something like ftpfs, is
> that it seems to behave differently than other types of binds.
> Examples I've used in the past involve simple binds like this.
> I create 4 directories, let's say dir1, dir2, dir3, dir4.
> Inside dir1 and dir2 I have files.
> I can then:
> bind -b dir1 dir3
> bind -b dir2 dir3
> then I can
> bind -b dir3 dir4
>
> When I look at ns
> I see not only a bind from dir3 to dir4,
> But I also see binds from dir1 to dir4, and dir2 to dir4. The act of
> binding dir3 to dir4 automatically seems to have created binds to dir1
> to dir4, and dir2 to dir4.
>
> So what I guess I was expecting to see from ns when using the ftpfs
> scenario, was to see not only a pipe bind to /n/ftp. But Also a pipe
> bind to my other location, since the other location was a bind to
> /n/ftp.
>
> On Sat, Dec 6, 2008 at 5:17 PM, Brad Frank <brad.frank@gmail.com> wrote:
>> I forgot to mention when I bind /n/ftp I was really binding
>> /n/ftp/directory to another location.
>>
>> On Sat, Dec 6, 2008 at 3:44 PM, Brad Frank <brad.frank@gmail.com> wrote:
>>> When I use ftpfs to mount a ftp site and then bind /n/ftp to another
>>> location. All appears to work fine in /n/ftp and in the other
>>> location. When I type ns, I can clearly see the pipe bind for ftpfs
>>> mounted to /n/ftp. When I unmount /n/ftp I can type ls on /n/ftp and
>>> not see anything there. But if I ls on the other location that I bound
>>> to /n/ftp, it still can access the ftp server. How is the other
>>> location able to do this, when I don't see any indication of a pipe
>>> bind still listed in ns? I do see the ftpfs process running, though.
>>>
>>
>

Re: [9fans] Explanation of binding from ftpfs

[Russ Cox]

ns is showing you the best name it has
for the resource in question.  if you did
bind /n/ftp/dir /n/tmp,
then it can't tell you that you did
mount '#s/ftp' /n/tmp
because that's not accurate--'#s/ftp' would
get you /n/ftp, not /n/ftp/dir.

so it shows you /n/ftp/dir, because that
is the name that was used at the time,
even if that name no longer means
the same thing.

russ