iov_iter: teach csum_and_copy_to_iter() to handle pipe-backed ones

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

iov_iter: Add I/O discard iterator

Add a new iterator, ITER_DISCARD, that can only be used in READ mode and
just discards any data copied to it.

This is useful in a network filesystem for discardin

iov_iter: Add I/O discard iterator

Add a new iterator, ITER_DISCARD, that can only be used in READ mode and
just discards any data copied to it.

This is useful in a network filesystem for discarding any unwanted data
sent by a server.

Signed-off-by: David Howells <dhowells@redhat.com>

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iov_iter: Separate type from direction and use accessor functions

In the iov_iter struct, separate the iterator type from the iterator
direction and use accessor functions to access them in most pla

iov_iter: Separate type from direction and use accessor functions

In the iov_iter struct, separate the iterator type from the iterator
direction and use accessor functions to access them in most places.

Convert a bunch of places to use switch-statements to access them rather
then chains of bitwise-AND statements. This makes it easier to add further
iterator types. Also, this can be more efficient as to implement a switch
of small contiguous integers, the compiler can use ~50% fewer compare
instructions than it has to use bitwise-and instructions.

Further, cease passing the iterator type into the iterator setup function.
The iterator function can set that itself. Only the direction is required.

Signed-off-by: David Howells <dhowells@redhat.com>

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iov_iter: Use accessor function

Use accessor functions to access an iterator's type and direction. This
allows for the possibility of using some other method of determining the
type of iterator tha

iov_iter: Use accessor function

Use accessor functions to access an iterator's type and direction. This
allows for the possibility of using some other method of determining the
type of iterator than if-chains with bitwise-AND conditions.

Signed-off-by: David Howells <dhowells@redhat.com>

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lib/iov_iter: Fix pipe handling in _copy_to_iter_mcsafe()

By mistake the ITER_PIPE early-exit / warning from copy_from_iter() was
cargo-culted in _copy_to_iter_mcsafe() rather than a machine-check-s

lib/iov_iter: Fix pipe handling in _copy_to_iter_mcsafe()

By mistake the ITER_PIPE early-exit / warning from copy_from_iter() was
cargo-culted in _copy_to_iter_mcsafe() rather than a machine-check-safe
version of copy_to_iter_pipe().

Implement copy_pipe_to_iter_mcsafe() being careful to return the
indication of short copies due to a CPU exception.

Without this regression-fix all splice reads to dax-mode files fail.

Reported-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Tested-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Fixes: 8780356ef630 ("x86/asm/memcpy_mcsafe: Define copy_to_iter_mcsafe()")
Link: http://lkml.kernel.org/r/153108277278.37979.3327916996902264102.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

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lib/iov_iter: Document _copy_to_iter_flushcache()

Add some theory of operation documentation to _copy_to_iter_flushcache().

Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Dan William

lib/iov_iter: Document _copy_to_iter_flushcache()

Add some theory of operation documentation to _copy_to_iter_flushcache().

Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Link: http://lkml.kernel.org/r/153108276767.37979.9462477994086841699.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

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lib/iov_iter: Document _copy_to_iter_mcsafe()

Add some theory of operation documentation to _copy_to_iter_mcsafe().

Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Dan Williams <dan.j

lib/iov_iter: Document _copy_to_iter_mcsafe()

Add some theory of operation documentation to _copy_to_iter_mcsafe().

Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Link: http://lkml.kernel.org/r/153108276256.37979.1689794213845539316.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

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x86/asm/memcpy_mcsafe: Define copy_to_iter_mcsafe()

Use the updated memcpy_mcsafe() implementation to define
copy_user_mcsafe() and copy_to_iter_mcsafe(). The most significant
difference from typica

x86/asm/memcpy_mcsafe: Define copy_to_iter_mcsafe()

Use the updated memcpy_mcsafe() implementation to define
copy_user_mcsafe() and copy_to_iter_mcsafe(). The most significant
difference from typical copy_to_iter() is that the ITER_KVEC and
ITER_BVEC iterator types can fail to complete a full transfer.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: hch@lst.de
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-nvdimm@lists.01.org
Link: http://lkml.kernel.org/r/152539239150.31796.9189779163576449784.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

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iov_iter: fix memory leak in pipe_get_pages_alloc()

Make n signed to avoid leaking the pages array if __pipe_get_pages()
fails to allocate any pages.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com

iov_iter: fix memory leak in pipe_get_pages_alloc()

Make n signed to avoid leaking the pages array if __pipe_get_pages()
fails to allocate any pages.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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iov_iter: fix return type of __pipe_get_pages()

It returns -EFAULT and happens to be a helper for pipe_get_pages()
whose return type is ssize_t.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Sig

iov_iter: fix return type of __pipe_get_pages()

It returns -EFAULT and happens to be a helper for pipe_get_pages()
whose return type is ssize_t.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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new primitive: iov_iter_for_each_range()

For kvec and bvec: feeds segments to given callback as long as it
returns 0. For iovec and pipe: fails.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

iov_iter: fix page_copy_sane for compound pages

Issue is that if the data crosses a page boundary inside a compound
page, this check will incorrectly trigger a WARN_ON.

To fix this, compute the ord

iov_iter: fix page_copy_sane for compound pages

Issue is that if the data crosses a page boundary inside a compound
page, this check will incorrectly trigger a WARN_ON.

To fix this, compute the order using the head of the compound page and
adjust the offset to be relative to that head.

Fixes: 72e809ed81ed ("iov_iter: sanity checks for copy to/from page
primitives")

Signed-off-by: Petar Penkov <ppenkov@google.com>
CC: Al Viro <viro@zeniv.linux.org.uk>
CC: Eric Dumazet <edumazet@google.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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iov_iter: saner checks on copyin/copyout

* might_fault() is better checked in caller (and e.g. fault-in + kmap_atomic
codepath also needs might_fault() coverage)
* we have already done object size c

iov_iter: saner checks on copyin/copyout

* might_fault() is better checked in caller (and e.g. fault-in + kmap_atomic
codepath also needs might_fault() coverage)
* we have already done object size checks
* we have *NOT* done access_ok() recently enough; we rely upon the
iovec array having passed sanity checks back when it had been created
and not nothing having buggered it since. However, that's very much
non-local, so we'd better recheck that.

So the thing we want does not match anything in uaccess - we need
access_ok + kasan checks + raw copy without any zeroing. Just define
such helpers and use them here.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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iov_iter: sanity checks for copy to/from page primitives

for now - just that we don't attempt to cross out of compound page

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

iov_iter/hardening: move object size checks to inlined part

There we actually have useful information about object sizes.
Note: this patch has them done for all iov_iter flavours.
Right now we do th

iov_iter/hardening: move object size checks to inlined part

There we actually have useful information about object sizes.
Note: this patch has them done for all iov_iter flavours.
Right now we do them twice in iovec case, but that'll change
very shortly.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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x86, uaccess: introduce copy_from_iter_flushcache for pmem / cache-bypass operations

The pmem driver has a need to transfer data with a persistent memory
destination and be able to rely on the fact

x86, uaccess: introduce copy_from_iter_flushcache for pmem / cache-bypass operations

The pmem driver has a need to transfer data with a persistent memory
destination and be able to rely on the fact that the destination writes are not
cached. It is sufficient for the writes to be flushed to a cpu-store-buffer
(non-temporal / "movnt" in x86 terms), as we expect userspace to call fsync()
to ensure data-writes have reached a power-fail-safe zone in the platform. The
fsync() triggers a REQ_FUA or REQ_FLUSH to the pmem driver which will turn
around and fence previous writes with an "sfence".

Implement a __copy_from_user_inatomic_flushcache, memcpy_page_flushcache, and
memcpy_flushcache, that guarantee that the destination buffer is not dirty in
the cpu cache on completion. The new copy_from_iter_flushcache and sub-routines
will be used to replace the "pmem api" (include/linux/pmem.h +
arch/x86/include/asm/pmem.h). The availability of copy_from_iter_flushcache()
and memcpy_flushcache() are gated by the CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
config symbol, and fallback to copy_from_iter_nocache() and plain memcpy()
otherwise.

This is meant to satisfy the concern from Linus that if a driver wants to do
something beyond the normal nocache semantics it should be something private to
that driver [1], and Al's concern that anything uaccess related belongs with
the rest of the uaccess code [2].

The first consumer of this interface is a new 'copy_from_iter' dax operation so
that pmem can inject cache maintenance operations without imposing this
overhead on other dax-capable drivers.

[1]: https://lists.01.org/pipermail/linux-nvdimm/2017-January/008364.html
[2]: https://lists.01.org/pipermail/linux-nvdimm/2017-April/009942.html

Cc: <x86@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

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treewide: use kv[mz]alloc* rather than opencoded variants

There are many code paths opencoding kvmalloc. Let's use the helper
instead. The main difference to kvmalloc is that those users are
usual

treewide: use kv[mz]alloc* rather than opencoded variants

There are many code paths opencoding kvmalloc. Let's use the helper
instead. The main difference to kvmalloc is that those users are
usually not considering all the aspects of the memory allocator. E.g.
allocation requests <= 32kB (with 4kB pages) are basically never failing
and invoke OOM killer to satisfy the allocation. This sounds too
disruptive for something that has a reasonable fallback - the vmalloc.
On the other hand those requests might fallback to vmalloc even when the
memory allocator would succeed after several more reclaim/compaction
attempts previously. There is no guarantee something like that happens
though.

This patch converts many of those places to kv[mz]alloc* helpers because
they are more conservative.

Link: http://lkml.kernel.org/r/20170306103327.2766-2-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> # Xen bits
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Andreas Dilger <andreas.dilger@intel.com> # Lustre
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com> # KVM/s390
Acked-by: Dan Williams <dan.j.williams@intel.com> # nvdim
Acked-by: David Sterba <dsterba@suse.com> # btrfs
Acked-by: Ilya Dryomov <idryomov@gmail.com> # Ceph
Acked-by: Tariq Toukan <tariqt@mellanox.com> # mlx4
Acked-by: Leon Romanovsky <leonro@mellanox.com> # mlx5
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Anton Vorontsov <anton@enomsg.org>
Cc: Colin Cross <ccross@android.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Kent Overstreet <kent.overstreet@gmail.com>
Cc: Santosh Raspatur <santosh@chelsio.com>
Cc: Hariprasad S <hariprasad@chelsio.com>
Cc: Yishai Hadas <yishaih@mellanox.com>
Cc: Oleg Drokin <oleg.drokin@intel.com>
Cc: "Yan, Zheng" <zyan@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

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fix braino in generic_file_read_iter()

Wrong sign of iov_iter_revert() argument. Unfortunately, slipped through
the testing, since most of the time we don't do anything to the iterator
afterwards a

fix braino in generic_file_read_iter()

Wrong sign of iov_iter_revert() argument. Unfortunately, slipped through
the testing, since most of the time we don't do anything to the iterator
afterwards and potential oops on walking the iter->iov too far backwards
is too infrequent to be easily triggered.

Add a sanity check in iov_iter_revert() to catch bugs like this one;
fortunately, the same braino hadn't happened in other callers, but we'd
better have a warning if such thing crops up.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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fix a braino in ITER_PIPE iov_iter_revert()

Fixes: 27c0e3748e41
Tested-by: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

[iov_iter] new privimitive: iov_iter_revert()

opposite to iov_iter_advance(); the caller is responsible for never
using it to move back past the initial position.

Cc: stable@vger.kernel.org
Signed-

[iov_iter] new privimitive: iov_iter_revert()

opposite to iov_iter_advance(); the caller is responsible for never
using it to move back past the initial position.

Cc: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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kill __copy_from_user_nocache()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

new helper: uaccess_kernel()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fix a fencepost error in pipe_advance()

The logics in pipe_advance() used to release all buffers past the new
position failed in cases when the number of buffers to release was equal
to pipe->buffer

fix a fencepost error in pipe_advance()

The logics in pipe_advance() used to release all buffers past the new
position failed in cases when the number of buffers to release was equal
to pipe->buffers. If that happened, none of them had been released,
leaving pipe full. Worse, it was trivial to trigger and we end up with
pipe full of uninitialized pages. IOW, it's an infoleak.

Cc: stable@vger.kernel.org # v4.9
Reported-by: "Alan J. Wylie" <alan@wylie.me.uk>
Tested-by: "Alan J. Wylie" <alan@wylie.me.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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[iov_iter] fix iterate_all_kinds() on empty iterators

Problem similar to ones dealt with in "fold checks into iterate_and_advance()"
and followups, except that in this case we really want to do noth

[iov_iter] fix iterate_all_kinds() on empty iterators

Problem similar to ones dealt with in "fold checks into iterate_and_advance()"
and followups, except that in this case we really want to do nothing when
asked for zero-length operation - unlike zero-length iterate_and_advance(),
zero-length iterate_all_kinds() has no side effects, and callers are simpler
that way.

That got exposed when copy_from_iter_full() had been used by tipc, which
builds an msghdr with zero payload and (now) feeds it to a primitive
based on iterate_all_kinds() instead of iterate_and_advance().

Reported-by: Jon Maloy <jon.maloy@ericsson.com>
Tested-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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[iov_iter] new primitives - copy_from_iter_full() and friends

copy_from_iter_full(), copy_from_iter_full_nocache() and
csum_and_copy_from_iter_full() - counterparts of copy_from_iter()
et.al., advan

[iov_iter] new primitives - copy_from_iter_full() and friends

copy_from_iter_full(), copy_from_iter_full_nocache() and
csum_and_copy_from_iter_full() - counterparts of copy_from_iter()
et.al., advancing iterator only in case of successful full copy
and returning whether it had been successful or not.

Convert some obvious users. *NOTE* - do not blindly assume that
something is a good candidate for those unless you are sure that
not advancing iov_iter in failure case is the right thing in
this case. Anything that does short read/short write kind of
stuff (or is in a loop, etc.) is unlikely to be a good one.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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