linux-stable.git/lib/iov_iter.c, branch v5.0.2

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2019-01-05T21:18:59+00:00

Pull trivial vfs updates from Al Viro:
 "A few cleanups + Neil's namespace_unlock() optimization"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  exec: make prepare_bprm_creds static
  genheaders: %-s had been there since v6; %-*s - since v7
  VFS: use synchronize_rcu_expedited() in namespace_unlock()
  iov_iter: reduce code duplication

Remove 'type' argument from access_ok() function

2019-01-04T02:57:57+00:00

Nobody has actually used the type (VERIFY_READ vs VERIFY_WRITE) argument
of the user address range verification function since we got rid of the
old racy i386-only code to walk page tables by hand.

It existed because the original 80386 would not honor the write protect
bit when in kernel mode, so you had to do COW by hand before doing any
user access.  But we haven't supported that in a long time, and these
days the 'type' argument is a purely historical artifact.

A discussion about extending 'user_access_begin()' to do the range
checking resulted this patch, because there is no way we're going to
move the old VERIFY_xyz interface to that model.  And it's best done at
the end of the merge window when I've done most of my merges, so let's
just get this done once and for all.

This patch was mostly done with a sed-script, with manual fix-ups for
the cases that weren't of the trivial 'access_ok(VERIFY_xyz' form.

There were a couple of notable cases:

 - csky still had the old "verify_area()" name as an alias.

 - the iter_iov code had magical hardcoded knowledge of the actual
   values of VERIFY_{READ,WRITE} (not that they mattered, since nothing
   really used it)

 - microblaze used the type argument for a debug printout

but other than those oddities this should be a total no-op patch.

I tried to fix up all architectures, did fairly extensive grepping for
access_ok() uses, and the changes are trivial, but I may have missed
something.  Any missed conversion should be trivially fixable, though.

Signed-off-by: Linus Torvalds

iov_iter: introduce hash_and_copy_to_iter helper

2018-12-13T08:58:54+00:00

Allow consumers that want to use iov iterator helpers and also update
a predefined hash calculation online when copying data. This is useful
when copying incoming network buffers to a local iterator and calculate
a digest on the incoming stream. nvme-tcp host driver that will be
introduced in following patches is the first consumer via
skb_copy_and_hash_datagram_iter.

Acked-by: David S. Miller 
Signed-off-by: Sagi Grimberg 
Signed-off-by: Christoph Hellwig

iov_iter: pass void csum pointer to csum_and_copy_to_iter

2018-12-13T08:58:53+00:00

The single caller to csum_and_copy_to_iter is skb_copy_and_csum_datagram
and we are trying to unite its logic with skb_copy_datagram_iter by passing
a callback to the copy function that we want to apply. Thus, we need
to make the checksum pointer private to the function.

Acked-by: David S. Miller 
Signed-off-by: Sagi Grimberg 
Signed-off-by: Christoph Hellwig

iov_iter: reduce code duplication

2018-11-28T03:35:08+00:00

The same combination of csum_partial_copy_nocheck() with csum_add_block()
is used in a bunch of places.  Add a helper doing just that and use it.

Signed-off-by: Al Viro

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

2018-11-25T21:24:49+00:00

Signed-off-by: Al Viro

iov_iter: Add I/O discard iterator

2018-10-23T23:41:07+00:00

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

iov_iter: Separate type from direction and use accessor functions

2018-10-23T23:41:07+00:00

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

iov_iter: Use accessor function

2018-10-23T23:40:44+00:00

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

lib/iov_iter: Fix pipe handling in _copy_to_iter_mcsafe()

2018-07-15T22:05:05+00:00

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 
Tested-by: Ross Zwisler 
Signed-off-by: Dan Williams 
Acked-by: Al Viro 
Cc: Andrew Morton 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Tony Luck 
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