From: Stanislav Kinsbursky <hidden> Date: 2012-08-10 13:00:15
Today, there is a problem in connecting of local SUNRPC thansports. These
transports uses UNIX sockets and connection itself is done by rpciod
workqueue.
But UNIX sockets lookup is done in context of process file system root. I.e.
all local thunsports are connecting in rpciod context.
This works nice until we will try to mount NFS from process with other root -
for example in container. This container can have it's own (nested) root and
rcpbind process, listening on it's own unix sockets. But NFS mount attempt in
this container will register new service (Lockd for example) in global rpcbind
- not containers's one.
This patch set introduces kernel connect helper for UNIX stream sockets and
modifies unix_find_other() to be able to search from specified root.
It also replaces generic socket connect call for local transports by new
helper in SUNRPC layer.
The following series implements...
---
Stanislav Kinsbursky (2):
unix sockets: add ability for search for peer from passed root
SUNRPC: connect local transports with unix_stream_connect_root() helper
include/net/af_unix.h | 2 ++
net/sunrpc/xprtsock.c | 28 +++++++++++++++++++++++++---
net/unix/af_unix.c | 25 ++++++++++++++++++-------
3 files changed, 45 insertions(+), 10 deletions(-)
From: Stanislav Kinsbursky <hidden> Date: 2012-08-10 13:00:07
This helper is used stream sockets yet.
All is simple: if non-NULL struct path was passed to unix_find_other(), then
vfs_path_lookup() is called instead of kern_path().
Signed-off-by: Stanislav Kinsbursky <redacted>
---
include/net/af_unix.h | 2 ++
net/unix/af_unix.c | 25 ++++++++++++++++++-------
2 files changed, 20 insertions(+), 7 deletions(-)
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From: J. Bruce Fields <hidden> Date: 2012-08-10 18:10:16
On Fri, Aug 10, 2012 at 04:57:30PM +0400, Stanislav Kinsbursky wrote:
This helper is used stream sockets yet.
All is simple: if non-NULL struct path was passed to unix_find_other(), then
vfs_path_lookup() is called instead of kern_path().
I'm having some trouble parsing the changelog. Maybe something like?:
unix sockets: add ability to look up using passed-in root
Export a unix_stream_connect_root() helper that allows a caller
to optionally pass in a root path, in which case the lookup will
be done relative to the given path instead of the current
working directory.
I guess this is a question for the networking people, but: will it cause
problems to have sunrpc calling directly into the unix socket code?
(And if so, what would be the alternative: define some variant of
sockaddr_un that includes the root path? Something better?)
--b.
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From: Stanislav Kinsbursky <hidden> Date: 2012-08-10 18:44:08
10.08.2012 22:10, J. Bruce Fields пишет:
On Fri, Aug 10, 2012 at 04:57:30PM +0400, Stanislav Kinsbursky wrote:
quoted
This helper is used stream sockets yet.
All is simple: if non-NULL struct path was passed to unix_find_other(), then
vfs_path_lookup() is called instead of kern_path().
I'm having some trouble parsing the changelog. Maybe something like?:
unix sockets: add ability to look up using passed-in root
Export a unix_stream_connect_root() helper that allows a caller
to optionally pass in a root path, in which case the lookup will
be done relative to the given path instead of the current
working directory.
Yep, your variant is much better. Thanks.
I guess this is a question for the networking people, but: will it cause
problems to have sunrpc calling directly into the unix socket code?
(And if so, what would be the alternative: define some variant of
sockaddr_un that includes the root path? Something better?)
That was my first idea. But there are problems with this solution (add
root path to sockaddr_un) :
1) sockaddr_un size will change. I don't know, how this will affect
user-space. Of course, we can introduce something like:
struct sockaddr_un_kern {
struct sockaddr_un un;
struct path *path;
}
But even in this case we need to color this structure somehow (for
example, set path to NULL for simple connect or bind call) . And to add
this color, we have to separate sys_connect () from our
sock->ops->connect() call. And I don't really know how to do it since we
don't have any info about socket type in sys_connect () in hands. I.e.
we have it, but then we have to add some specific UNIX socket logic to
completely generic sys_connect () and sys_bind () .
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From: Stanislav Kinsbursky <hidden> Date: 2012-08-10 13:00:50
Today, there is a problem in connecting of local SUNRPC thansports. These
transports uses UNIX sockets and connection itself is done by rpciod
workqueue.
But UNIX sockets lookup is done in context of process file system root. I.e.
all local thunsports are connecting in rpciod context.
This works nice until we will try to mount NFS from process with other root -
for example in container. This container can have it's own (nested) root and
rcpbind process, listening on it's own unix sockets. But NFS mount attempt in
this container will register new service (Lockd for example) in global rpcbind
- not containers's one.
This patch solves the problem by using special helper
unix_stream_connect_root(), which lookup socket file starting from passed
root.
Signed-off-by: Stanislav Kinsbursky <redacted>
---
net/sunrpc/xprtsock.c | 28 +++++++++++++++++++++++++---
1 files changed, 25 insertions(+), 3 deletions(-)
@@ -2607,8 +2627,10 @@ static struct rpc_xprt *xs_setup_local(struct xprt_create *args)dprintk("RPC: set up xprt to %s via AF_LOCAL\n",xprt->address_strings[RPC_DISPLAY_ADDR]);-if(try_module_get(THIS_MODULE))+if(try_module_get(THIS_MODULE)){+get_fs_root(current->fs,&transport->root);returnxprt;+}ret=ERR_PTR(-EINVAL);out_err:xprt_free(xprt);
From: "H. Peter Anvin" <hpa@zytor.com> Date: 2012-08-10 18:16:18
On 08/10/2012 05:57 AM, Stanislav Kinsbursky wrote:
Today, there is a problem in connecting of local SUNRPC thansports. These
transports uses UNIX sockets and connection itself is done by rpciod
workqueue.
But UNIX sockets lookup is done in context of process file system root. I.e.
all local thunsports are connecting in rpciod context.
This works nice until we will try to mount NFS from process with other root -
for example in container. This container can have it's own (nested) root and
rcpbind process, listening on it's own unix sockets. But NFS mount attempt in
this container will register new service (Lockd for example) in global rpcbind
- not containers's one.
This patch set introduces kernel connect helper for UNIX stream sockets and
modifies unix_find_other() to be able to search from specified root.
It also replaces generic socket connect call for local transports by new
helper in SUNRPC layer.
The following series implements...
On that whole subject...
Do we need a Unix domain socket equivalent to openat()?
-hpa
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On that whole subject...
Do we need a Unix domain socket equivalent to openat()?
I don't think so. The name is just a file system indexing trick, it's not
really the socket proper. It's little more than "ascii string with
permissions attached" - indeed we also support an abstract name space
which for a lot of uses is actually more convenient.
AF_UNIX between roots raises some interesting semantic questions when you
begin passing file descriptors down them as well.
Alan
From: "H. Peter Anvin" <hpa@zytor.com> Date: 2012-08-10 18:31:48
On 08/10/2012 11:26 AM, Alan Cox wrote:
quoted
On that whole subject...
Do we need a Unix domain socket equivalent to openat()?
I don't think so. The name is just a file system indexing trick, it's not
really the socket proper. It's little more than "ascii string with
permissions attached" - indeed we also support an abstract name space
which for a lot of uses is actually more convenient.
I don't really understand why Unix domain sockets is different than any
other pathname users in this sense. (Actually, I have never understood
why open() on a Unix domain socket doesn't give the equivalent of a
socket() + connect() -- it would make logical sense and would provide
additional functionality).
It would be different if the Unix domain sockets simply required an
absolute pathname (it is not just about the root, it is also about the
cwd, which is where the -at() functions come into play), but that is not
the case.
The abstract namespace is irrelevant for this, obviously.
AF_UNIX between roots raises some interesting semantic questions when
you begin passing file descriptors down them as well.
Why is that? A file descriptor carries all that information with it...
-hpa
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AF_UNIX between roots raises some interesting semantic questions when
you begin passing file descriptors down them as well.
Why is that? A file descriptor carries all that information with it...
Things like fchdir(). It's not a machine breaking problem but for
containers as opposed to chroot we need to be clear what the expected
isolation sematics are.
Agreed on open() for sockets.. the lack of open is a Berklix derived
pecularity of the interface. It would equally be useful to be able to
open "/dev/socket/ipv4/1.2.3.4/1135" and the like for scripts and stuff
That needs VFS changes however so you can pass the remainder of a path to
a device node. It also lets you do a lot of other sane stuff like
open /dev/ttyS0/9600/8n1
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From: "H. Peter Anvin" <hpa@zytor.com> Date: 2012-08-10 18:44:16
On 08/10/2012 11:40 AM, Alan Cox wrote:
Agreed on open() for sockets.. the lack of open is a Berklix derived
pecularity of the interface. It would equally be useful to be able to
open "/dev/socket/ipv4/1.2.3.4/1135" and the like for scripts and stuff
That needs VFS changes however so you can pass the remainder of a path to
a device node. It also lets you do a lot of other sane stuff like
open /dev/ttyS0/9600/8n1
Well, supporting device node subpaths would be nice, but I don't think
that that is a requirement either for being able to open() a socket (as
a Linux extension) nor for supporting something like your above
/dev/socket/... since that could be done with a filesystem rather than
just a device node.
-hpa
From: J. Bruce Fields <hidden> Date: 2012-08-10 19:12:07
On Fri, Aug 10, 2012 at 07:26:28PM +0100, Alan Cox wrote:
quoted
On that whole subject...
Do we need a Unix domain socket equivalent to openat()?
I don't think so. The name is just a file system indexing trick, it's not
really the socket proper. It's little more than "ascii string with
permissions attached"
That's overstating the case. As I understand it the address is resolved
by a pathname lookup like any other--it can follow symlinks, is relative
to the current working directory and filesystem namespace, etc. So a
unix-domain socket equivalent to openat() would at least be
well-defined--whether it's needed or not, I don't know.
--b.
On Fri, 10 Aug 2012 15:11:50 -0400
"J. Bruce Fields" [off-list ref] wrote:
On Fri, Aug 10, 2012 at 07:26:28PM +0100, Alan Cox wrote:
quoted
quoted
On that whole subject...
Do we need a Unix domain socket equivalent to openat()?
I don't think so. The name is just a file system indexing trick, it's not
really the socket proper. It's little more than "ascii string with
permissions attached"
That's overstating the case. As I understand it the address is resolved
by a pathname lookup like any other--it can follow symlinks, is relative
to the current working directory and filesystem namespace, etc.
Explicitly for Linux yes - this is not generally true of the AF_UNIX
socket domain and even the permissions aspect isn't guaranteed to be
supported on some BSD environments !
The name is however just a proxy for the socket itself. You don't even
get a device node in the usual sense or the same inode in the file system
space.
Alan
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From: "H. Peter Anvin" <hpa@zytor.com> Date: 2012-08-10 23:10:01
On 08/10/2012 12:28 PM, Alan Cox wrote:
Explicitly for Linux yes - this is not generally true of the AF_UNIX
socket domain and even the permissions aspect isn't guaranteed to be
supported on some BSD environments !
Yes, but let's worry about what the Linux behavior should be.
The name is however just a proxy for the socket itself. You don't even
get a device node in the usual sense or the same inode in the file system
space.
No, but it is looked up the same way any other inode is (the difference
between FIFOs and sockets is that sockets have separate connections,
which is also why open() on sockets would be nice.)
However, there is a fundamental difference between AF_UNIX sockets and
open(), and that is how the pathname is delivered. It thus would make
more sense to provide the openat()-like information in struct
sockaddr_un, but that may be very hard to do in a sensible way. In that
sense it perhaps would be cleaner to be able to do an open[at]() on the
socket node with O_PATH (perhaps there should be an O_SOCKET option,
even?) and pass the resulting file descriptor to bind() or connect().
-hpa
From: Pavel Emelyanov <hidden> Date: 2012-08-11 06:24:07
On 08/11/2012 03:09 AM, H. Peter Anvin wrote:
On 08/10/2012 12:28 PM, Alan Cox wrote:
quoted
Explicitly for Linux yes - this is not generally true of the AF_UNIX
socket domain and even the permissions aspect isn't guaranteed to be
supported on some BSD environments !
Yes, but let's worry about what the Linux behavior should be.
quoted
The name is however just a proxy for the socket itself. You don't even
get a device node in the usual sense or the same inode in the file system
space.
No, but it is looked up the same way any other inode is (the difference
between FIFOs and sockets is that sockets have separate connections,
which is also why open() on sockets would be nice.)
However, there is a fundamental difference between AF_UNIX sockets and
open(), and that is how the pathname is delivered. It thus would make
more sense to provide the openat()-like information in struct
sockaddr_un, but that may be very hard to do in a sensible way. In that
sense it perhaps would be cleaner to be able to do an open[at]() on the
socket node with O_PATH (perhaps there should be an O_SOCKET option,
even?) and pass the resulting file descriptor to bind() or connect().
I vote for this (openat + O_WHATEVER on a unix socket) as well. It will
help us in checkpoint-restore, making handling of overmounted/unlinked
sockets much cleaner.
-hpa
Thanks,
Pavel
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From: Stanislav Kinsbursky <hidden> Date: 2012-08-11 11:15:54
11.08.2012 10:23, Pavel Emelyanov пишет:
On 08/11/2012 03:09 AM, H. Peter Anvin wrote:
quoted
On 08/10/2012 12:28 PM, Alan Cox wrote:
quoted
Explicitly for Linux yes - this is not generally true of the AF_UNIX
socket domain and even the permissions aspect isn't guaranteed to be
supported on some BSD environments !
Yes, but let's worry about what the Linux behavior should be.
quoted
The name is however just a proxy for the socket itself. You don't even
get a device node in the usual sense or the same inode in the file system
space.
No, but it is looked up the same way any other inode is (the difference
between FIFOs and sockets is that sockets have separate connections,
which is also why open() on sockets would be nice.)
However, there is a fundamental difference between AF_UNIX sockets and
open(), and that is how the pathname is delivered. It thus would make
more sense to provide the openat()-like information in struct
sockaddr_un, but that may be very hard to do in a sensible way. In that
sense it perhaps would be cleaner to be able to do an open[at]() on the
socket node with O_PATH (perhaps there should be an O_SOCKET option,
even?) and pass the resulting file descriptor to bind() or connect().
I vote for this (openat + O_WHATEVER on a unix socket) as well. It will
help us in checkpoint-restore, making handling of overmounted/unlinked
sockets much cleaner.
I have to notice, that it's not enough and doesn't solve the issue.
There should be some way how to connect/bind already existent unix
socket (from kernel, at least), because socket can be created in user space.
And this way (sock operation or whatever) have to provide an ability to
lookup UNIX socket starting from specified root to support containers.
From: J. Bruce Fields <hidden> Date: 2012-08-13 16:47:47
On Sat, Aug 11, 2012 at 03:15:24PM +0400, Stanislav Kinsbursky wrote:
11.08.2012 10:23, Pavel Emelyanov пишет:
quoted
On 08/11/2012 03:09 AM, H. Peter Anvin wrote:
quoted
On 08/10/2012 12:28 PM, Alan Cox wrote:
quoted
Explicitly for Linux yes - this is not generally true of the AF_UNIX
socket domain and even the permissions aspect isn't guaranteed to be
supported on some BSD environments !
Yes, but let's worry about what the Linux behavior should be.
quoted
The name is however just a proxy for the socket itself. You don't even
get a device node in the usual sense or the same inode in the file system
space.
No, but it is looked up the same way any other inode is (the difference
between FIFOs and sockets is that sockets have separate connections,
which is also why open() on sockets would be nice.)
However, there is a fundamental difference between AF_UNIX sockets and
open(), and that is how the pathname is delivered. It thus would make
more sense to provide the openat()-like information in struct
sockaddr_un, but that may be very hard to do in a sensible way. In that
sense it perhaps would be cleaner to be able to do an open[at]() on the
socket node with O_PATH (perhaps there should be an O_SOCKET option,
even?) and pass the resulting file descriptor to bind() or connect().
I vote for this (openat + O_WHATEVER on a unix socket) as well. It will
help us in checkpoint-restore, making handling of overmounted/unlinked
sockets much cleaner.
I have to notice, that it's not enough and doesn't solve the issue.
There should be some way how to connect/bind already existent unix
socket (from kernel, at least), because socket can be created in
user space.
And this way (sock operation or whatever) have to provide an ability
to lookup UNIX socket starting from specified root to support
containers.
I don't understand--the rpcbind sockets are created by the kernel. What
am I missing?
--b.
From: Stanislav Kinsbursky <hidden> Date: 2012-08-13 17:40:00
13.08.2012 20:47, J. Bruce Fields пишет:
On Sat, Aug 11, 2012 at 03:15:24PM +0400, Stanislav Kinsbursky wrote:
quoted
11.08.2012 10:23, Pavel Emelyanov пишет:
quoted
On 08/11/2012 03:09 AM, H. Peter Anvin wrote:
quoted
On 08/10/2012 12:28 PM, Alan Cox wrote:
quoted
Explicitly for Linux yes - this is not generally true of the AF_UNIX
socket domain and even the permissions aspect isn't guaranteed to be
supported on some BSD environments !
Yes, but let's worry about what the Linux behavior should be.
quoted
The name is however just a proxy for the socket itself. You don't even
get a device node in the usual sense or the same inode in the file system
space.
No, but it is looked up the same way any other inode is (the difference
between FIFOs and sockets is that sockets have separate connections,
which is also why open() on sockets would be nice.)
However, there is a fundamental difference between AF_UNIX sockets and
open(), and that is how the pathname is delivered. It thus would make
more sense to provide the openat()-like information in struct
sockaddr_un, but that may be very hard to do in a sensible way. In that
sense it perhaps would be cleaner to be able to do an open[at]() on the
socket node with O_PATH (perhaps there should be an O_SOCKET option,
even?) and pass the resulting file descriptor to bind() or connect().
I vote for this (openat + O_WHATEVER on a unix socket) as well. It will
help us in checkpoint-restore, making handling of overmounted/unlinked
sockets much cleaner.
I have to notice, that it's not enough and doesn't solve the issue.
There should be some way how to connect/bind already existent unix
socket (from kernel, at least), because socket can be created in
user space.
And this way (sock operation or whatever) have to provide an ability
to lookup UNIX socket starting from specified root to support
containers.
I don't understand--the rpcbind sockets are created by the kernel. What
am I missing?
From: J. Bruce Fields <hidden> Date: 2012-08-13 18:24:45
On Mon, Aug 13, 2012 at 09:39:53PM +0400, Stanislav Kinsbursky wrote:
13.08.2012 20:47, J. Bruce Fields пишет:
quoted
On Sat, Aug 11, 2012 at 03:15:24PM +0400, Stanislav Kinsbursky wrote:
quoted
11.08.2012 10:23, Pavel Emelyanov пишет:
quoted
On 08/11/2012 03:09 AM, H. Peter Anvin wrote:
quoted
On 08/10/2012 12:28 PM, Alan Cox wrote:
quoted
Explicitly for Linux yes - this is not generally true of the AF_UNIX
socket domain and even the permissions aspect isn't guaranteed to be
supported on some BSD environments !
Yes, but let's worry about what the Linux behavior should be.
quoted
The name is however just a proxy for the socket itself. You don't even
get a device node in the usual sense or the same inode in the file system
space.
No, but it is looked up the same way any other inode is (the difference
between FIFOs and sockets is that sockets have separate connections,
which is also why open() on sockets would be nice.)
However, there is a fundamental difference between AF_UNIX sockets and
open(), and that is how the pathname is delivered. It thus would make
more sense to provide the openat()-like information in struct
sockaddr_un, but that may be very hard to do in a sensible way. In that
sense it perhaps would be cleaner to be able to do an open[at]() on the
socket node with O_PATH (perhaps there should be an O_SOCKET option,
even?) and pass the resulting file descriptor to bind() or connect().
I vote for this (openat + O_WHATEVER on a unix socket) as well. It will
help us in checkpoint-restore, making handling of overmounted/unlinked
sockets much cleaner.
I have to notice, that it's not enough and doesn't solve the issue.
There should be some way how to connect/bind already existent unix
socket (from kernel, at least), because socket can be created in
user space.
And this way (sock operation or whatever) have to provide an ability
to lookup UNIX socket starting from specified root to support
containers.
I don't understand--the rpcbind sockets are created by the kernel. What
am I missing?
I'm confused, possibly because there are three "sockets" here: the
client-side socket that's connected, the server-side socket that's
bound, and the common object that exists in the filesystem namespace.
Userland creates the server-side socket and binds to it. All of that is
done in the context of the rpcbind process, so is created in rpcbind's
namespace. That should be OK, right?
The client side socket is created and connected in
xs_local_setup_socket().
Making sure they both end up with the same thing is a matter of making
sure they lookup the same path in the same namespace. The difficult
part of that is the in-kernel client-side socket connect, where we don't
have the right process context any more.
We currently set that up with __sock_create followed by
kernel_connect.
The proposal seems to be to instead do an openat followed by a
kernel_connect, and pass the path in the openat instead of the connect.
(Though in the kernel we won't be able to call openat, so we'll end up
doing something like nfsd does (calling lookup_one_len() and
dentry_open() by hand).)
Have I got all that right?
I don't know if that's better just calling into the unix socket code at
connect time as your patch does. Maybe the answer depends on whether
it's a priority to make this functionality available to userspace.
--b.
From: Stanislav Kinsbursky <hidden> Date: 2012-08-14 08:46:45
13.08.2012 22:24, J. Bruce Fields пишет:
On Mon, Aug 13, 2012 at 09:39:53PM +0400, Stanislav Kinsbursky wrote:
quoted
13.08.2012 20:47, J. Bruce Fields пишет:
quoted
On Sat, Aug 11, 2012 at 03:15:24PM +0400, Stanislav Kinsbursky wrote:
quoted
11.08.2012 10:23, Pavel Emelyanov пишет:
quoted
On 08/11/2012 03:09 AM, H. Peter Anvin wrote:
quoted
On 08/10/2012 12:28 PM, Alan Cox wrote:
quoted
Explicitly for Linux yes - this is not generally true of the
AF_UNIX socket domain and even the permissions aspect isn't
guaranteed to be supported on some BSD environments !
Yes, but let's worry about what the Linux behavior should be.
quoted
The name is however just a proxy for the socket itself. You
don't even get a device node in the usual sense or the same inode
in the file system space.
No, but it is looked up the same way any other inode is (the
difference between FIFOs and sockets is that sockets have separate
connections, which is also why open() on sockets would be nice.)
However, there is a fundamental difference between AF_UNIX sockets
and open(), and that is how the pathname is delivered. It thus
would make more sense to provide the openat()-like information in
struct sockaddr_un, but that may be very hard to do in a sensible
way. In that sense it perhaps would be cleaner to be able to do
an open[at]() on the socket node with O_PATH (perhaps there should
be an O_SOCKET option, even?) and pass the resulting file
descriptor to bind() or connect().
I vote for this (openat + O_WHATEVER on a unix socket) as well. It
will help us in checkpoint-restore, making handling of
overmounted/unlinked sockets much cleaner.
I have to notice, that it's not enough and doesn't solve the issue.
There should be some way how to connect/bind already existent unix
socket (from kernel, at least), because socket can be created in user
space. And this way (sock operation or whatever) have to provide an
ability to lookup UNIX socket starting from specified root to support
containers.
I don't understand--the rpcbind sockets are created by the kernel. What
am I missing?
I'm confused, possibly because there are three "sockets" here: the
client-side socket that's connected, the server-side socket that's bound,
and the common object that exists in the filesystem namespace.
Userland creates the server-side socket and binds to it. All of that is
done in the context of the rpcbind process, so is created in rpcbind's
namespace. That should be OK, right?
The client side socket is created and connected in xs_local_setup_socket().
Making sure they both end up with the same thing is a matter of making sure
they lookup the same path in the same namespace. The difficult part of that
is the in-kernel client-side socket connect, where we don't have the right
process context any more.
Looks like I'm missing something important.
Where are these UNIX in-kernel created and listening sockets (in code, I mean)?
--
Best regards,
Stanislav Kinsbursky
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From: Stanislav Kinsbursky <hidden> Date: 2012-08-10 18:50:54
10.08.2012 22:15, H. Peter Anvin пишет:
On 08/10/2012 05:57 AM, Stanislav Kinsbursky wrote:
quoted
Today, there is a problem in connecting of local SUNRPC thansports. These
transports uses UNIX sockets and connection itself is done by rpciod
workqueue.
But UNIX sockets lookup is done in context of process file system root. I.e.
all local thunsports are connecting in rpciod context.
This works nice until we will try to mount NFS from process with other root -
for example in container. This container can have it's own (nested) root and
rcpbind process, listening on it's own unix sockets. But NFS mount attempt in
this container will register new service (Lockd for example) in global rpcbind
- not containers's one.
This patch set introduces kernel connect helper for UNIX stream sockets and
modifies unix_find_other() to be able to search from specified root.
It also replaces generic socket connect call for local transports by new
helper in SUNRPC layer.
The following series implements...
On that whole subject...
Do we need a Unix domain socket equivalent to openat()?
It looks like sys_connectat () and sys_bindat () could be an organic
part on openat () and friends family.
But currently I don't have any usage example for them in hands. And the
main problem here, that this syscalls can be used only for unix sockets.