Massaged cp_compat_stat() into form closer to cp_new_stat(); the only real issue had been in handling of st_nlink overflows - native 32bit stat(2) returns -EOVERFLOW in such situations, compat one silently loses upper bits. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
... and bury user_get_super()/statfs_by_dentry() - they are purely internal now. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The basic idea behind cross memory attach is to allow MPI programs doing
intra-node communication to do a single copy of the message rather than a
double copy of the message via shared memory.
The following patch attempts to achieve this by allowing a destination
process, given an address and size from a source process, to copy memory
directly from the source process into its own address space via a system
call. There is also a symmetrical ability to copy from the current
process's address space into a destination process's address space.
- Use of /proc/pid/mem has been considered, but there are issues with
using it:
- Does not allow for specifying iovecs for both src and dest, assuming
preadv or pwritev was implemented either the area read from or
written to would need to be contiguous.
- Currently mem_read allows only processes who are currently
ptrace'ing the target and are still able to ptrace the target to read
from the target. This check could possibly be moved to the open call,
but its not clear exactly what race this restriction is stopping
(reason appears to have been lost)
- Having to send the fd of /proc/self/mem via SCM_RIGHTS on unix
domain socket is a bit ugly from a userspace point of view,
especially when you may have hundreds if not (eventually) thousands
of processes that all need to do this with each other
- Doesn't allow for some future use of the interface we would like to
consider adding in the future (see below)
- Interestingly reading from /proc/pid/mem currently actually
involves two copies! (But this could be fixed pretty easily)
As mentioned previously use of vmsplice instead was considered, but has
problems. Since you need the reader and writer working co-operatively if
the pipe is not drained then you block. Which requires some wrapping to
do non blocking on the send side or polling on the receive. In all to all
communication it requires ordering otherwise you can deadlock. And in the
example of many MPI tasks writing to one MPI task vmsplice serialises the
copying.
There are some cases of MPI collectives where even a single copy interface
does not get us the performance gain we could. For example in an
MPI_Reduce rather than copy the data from the source we would like to
instead use it directly in a mathops (say the reduce is doing a sum) as
this would save us doing a copy. We don't need to keep a copy of the data
from the source. I haven't implemented this, but I think this interface
could in the future do all this through the use of the flags - eg could
specify the math operation and type and the kernel rather than just
copying the data would apply the specified operation between the source
and destination and store it in the destination.
Although we don't have a "second user" of the interface (though I've had
some nibbles from people who may be interested in using it for intra
process messaging which is not MPI). This interface is something which
hardware vendors are already doing for their custom drivers to implement
fast local communication. And so in addition to this being useful for
OpenMPI it would mean the driver maintainers don't have to fix things up
when the mm changes.
There was some discussion about how much faster a true zero copy would
go. Here's a link back to the email with some testing I did on that:
http://marc.info/?l=linux-mm&m=130105930902915&w=2
There is a basic man page for the proposed interface here:
http://ozlabs.org/~cyeoh/cma/process_vm_readv.txt
This has been implemented for x86 and powerpc, other architecture should
mainly (I think) just need to add syscall numbers for the process_vm_readv
and process_vm_writev. There are 32 bit compatibility versions for
64-bit kernels.
For arch maintainers there are some simple tests to be able to quickly
verify that the syscalls are working correctly here:
http://ozlabs.org/~cyeoh/cma/cma-test-20110718.tgz
Signed-off-by: Chris Yeoh <yeohc@au1.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Howells <dhowells@redhat.com>
Cc: James Morris <jmorris@namei.org>
Cc: <linux-man@vger.kernel.org>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/hch/vfs-queue: (21 commits) leases: fix write-open/read-lease race nfs: drop unnecessary locking in llseek ext4: replace cut'n'pasted llseek code with generic_file_llseek_size vfs: add generic_file_llseek_size vfs: do (nearly) lockless generic_file_llseek direct-io: merge direct_io_walker into __blockdev_direct_IO direct-io: inline the complete submission path direct-io: separate map_bh from dio direct-io: use a slab cache for struct dio direct-io: rearrange fields in dio/dio_submit to avoid holes direct-io: fix a wrong comment direct-io: separate fields only used in the submission path from struct dio vfs: fix spinning prevention in prune_icache_sb vfs: add a comment to inode_permission() vfs: pass all mask flags check_acl and posix_acl_permission vfs: add hex format for MAY_* flag values vfs: indicate that the permission functions take all the MAY_* flags compat: sync compat_stats with statfs. vfs: add "device" tag to /proc/self/mountstats cleanup: vfs: small comment fix for block_invalidatepage ... Fix up trivial conflict in fs/gfs2/file.c (llseek changes)
This was found by inspection while tracking a similar bug in compat_statfs64, that has been fixed in mainline since decemeber. - This fixes a bug where not all of the f_spare fields were cleared on mips and s390. - Add the f_flags field to struct compat_statfs - Copy f_flags to userspace in case someone cares. - Use __clear_user to copy the f_spare field to userspace to ensure that all of the elements of f_spare are cleared. On some architectures f_spare is has 5 ints and on some architectures f_spare only has 4 ints. Which makes the previous technique of clearing each int individually broken. I don't expect anyone actually uses the old statfs system call anymore but if they do let them benefit from having the compat and the native version working the same. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
* 'for-3.2' of git://linux-nfs.org/~bfields/linux: (103 commits) nfs41: implement DESTROY_CLIENTID operation nfsd4: typo logical vs bitwise negate for want_mask nfsd4: allow NFS4_SHARE_SIGNAL_DELEG_WHEN_RESRC_AVAIL | NFS4_SHARE_PUSH_DELEG_WHEN_UNCONTENDED nfsd4: seq->status_flags may be used unitialized nfsd41: use SEQ4_STATUS_BACKCHANNEL_FAULT when cb_sequence is invalid nfsd4: implement new 4.1 open reclaim types nfsd4: remove unneeded CLAIM_DELEGATE_CUR workaround nfsd4: warn on open failure after create nfsd4: preallocate open stateid in process_open1() nfsd4: do idr preallocation with stateid allocation nfsd4: preallocate nfs4_file in process_open1() nfsd4: clean up open owners on OPEN failure nfsd4: simplify process_open1 logic nfsd4: make is_open_owner boolean nfsd4: centralize renew_client() calls nfsd4: typo logical vs bitwise negate nfs: fix bug about IPv6 address scope checking nfsd4: more robust ignoring of WANT bits in OPEN nfsd4: move name-length checks to xdr nfsd4: move access/deny validity checks to xdr code ...
We don't need this any more. Signed-off-by: J. Bruce Fields <bfields@redhat.com>
The nfsservctl system call is now gone, so we should remove all linkage for it. Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: J. Bruce Fields <bfields@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
As promised in feature-removal-schedule.txt it is time to remove the nfsctl system call. Userspace has perferred to not use this call throughout 2.6 and it has been excluded in the default configuration since 2.6.36 (9 months ago). So this patch removes all the code that was being compiled out. There are still references to sys_nfsctl in various arch systemcall tables and related code. These should be cleaned out too, probably in the next merge window. Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: J. Bruce Fields <bfields@redhat.com>