fix iov_iter_advance() for ITER_PIPE

iov_iter_advance() needs to decrement iter->count by the number of
bytes we'd moved beyond. Normal flavours do that, but ITER_PIPE
doesn't and ITER_PIPE generic

fix iov_iter_advance() for ITER_PIPE

iov_iter_advance() needs to decrement iter->count by the number of
bytes we'd moved beyond. Normal flavours do that, but ITER_PIPE
doesn't and ITER_PIPE generic_file_read_iter() for O_DIRECT files
ends up with a bogus fallback to page cache read, resulting in incorrect
values for file offset and bytes read.

Signed-off-by: Abhi Das <adas@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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block,fs: untangle fs.h and blk_types.h

Nothing in fs.h should require blk_types.h to be included.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

iov_iter: kernel-doc import_iovec() and rw_copy_check_uvector()

Both import_iovec() and rw_copy_check_uvector() take an array
(typically small and on-stack) which is used to hold an iovec array copy

iov_iter: kernel-doc import_iovec() and rw_copy_check_uvector()

Both import_iovec() and rw_copy_check_uvector() take an array
(typically small and on-stack) which is used to hold an iovec array copy
from userspace. This is to avoid an expensive memory allocation in the
fast path (i.e. few iovec elements).

The caller may have to check whether these functions actually used
the provided buffer or allocated a new one -- but this differs between
the too. Let's just add a kernel doc to clarify what the semantics are
for each function.

Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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Fix off-by-one in __pipe_get_pages()

it actually worked only when requested area ended on the page boundary...

Reported-by: Marco Grassi <marco.gra@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.lin

Fix off-by-one in __pipe_get_pages()

it actually worked only when requested area ended on the page boundary...

Reported-by: Marco Grassi <marco.gra@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

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pipe: add pipe_buf_release() helper

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

new iov_iter flavour: pipe-backed

iov_iter variant for passing data into pipe. copy_to_iter()
copies data into page(s) it has allocated and stuffs them into
the pipe; copy_page_to_iter() stuffs the

new iov_iter flavour: pipe-backed

iov_iter variant for passing data into pipe. copy_to_iter()
copies data into page(s) it has allocated and stuffs them into
the pipe; copy_page_to_iter() stuffs there a reference to the
page given to it. Both will try to coalesce if possible.
iov_iter_zero() is similar to copy_to_iter(); iov_iter_get_pages()
and friends will do as copy_to_iter() would have and return the
pages where the data would've been copied. iov_iter_advance()
will truncate everything past the spot it has advanced to.

New primitive: iov_iter_pipe(), used for initializing those.
pipe should be locked all along.

Running out of space acts as fault would for iovec-backed ones;
in other words, giving it to ->read_iter() may result in short
read if the pipe overflows, or -EFAULT if it happens with nothing
copied there.

In other words, ->read_iter() on those acts pretty much like
->splice_read(). Moreover, all generic_file_splice_read() users,
as well as many other ->splice_read() instances can be switched
to that scheme - that'll happen in the next commit.

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

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get rid of separate multipage fault-in primitives

* the only remaining callers of "short" fault-ins are just as happy with generic
variants (both in lib/iov_iter.c); switch them to multipage variant

get rid of separate multipage fault-in primitives

* the only remaining callers of "short" fault-ins are just as happy with generic
variants (both in lib/iov_iter.c); switch them to multipage variants, kill the
"short" ones
* rename the multipage variants to now available plain ones.
* get rid of compat macro defining iov_iter_fault_in_multipage_readable by
expanding it in its only user.

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

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fix iov_iter_fault_in_readable()

... by turning it into what used to be multipages counterpart

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

fix iov_iter_fault_in_readable()

... by turning it into what used to be multipages counterpart

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

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mm: optimize copy_page_to/from_iter_iovec

copy_page_to_iter_iovec() and copy_page_from_iter_iovec() copy some data
to userspace or from userspace. These functions have a fast path where
they map a

mm: optimize copy_page_to/from_iter_iovec

copy_page_to_iter_iovec() and copy_page_from_iter_iovec() copy some data
to userspace or from userspace. These functions have a fast path where
they map a page using kmap_atomic and a slow path where they use kmap.

kmap is slower than kmap_atomic, so the fast path is preferred.

However, on kernels without highmem support, kmap just calls
page_address, so there is no need to avoid kmap. On kernels without
highmem support, the fast path just increases code size (and cache
footprint) and it doesn't improve copy performance in any way.

This patch enables the fast path only if CONFIG_HIGHMEM is defined.

Code size reduced by this patch:
x86 (without highmem) 928
x86-64 960
sparc64 848
alpha 1136
pa-risc 1200

[akpm@linux-foundation.org: use IS_ENABLED(), per Andi]
Link: http://lkml.kernel.org/r/alpine.LRH.2.02.1607221711410.4818@file01.intranet.prod.int.rdu2.redhat.com
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

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iov_iter: use bvec iterator to implement iterate_bvec()

bvec has one native/mature iterator for long time, so not
necessary to use the reinvented wheel for iterating bvecs
in lib/iov_iter.c.

Two IT

iov_iter: use bvec iterator to implement iterate_bvec()

bvec has one native/mature iterator for long time, so not
necessary to use the reinvented wheel for iterating bvecs
in lib/iov_iter.c.

Two ITER_BVEC test cases are run:
- xfstest(-g auto) on loop dio/aio, no regression found
- swap file works well under extreme stress(stress-ng --all 64 -t
800 -v), and lots of OOMs are triggerd, and the whole
system still survives

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Tested-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

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do "fold checks into iterate_and_advance()" right

the only case when we should skip the iterate_and_advance() guts
is when nothing's left in the iterator, _not_ just when requested
amount is 0. Sai

do "fold checks into iterate_and_advance()" right

the only case when we should skip the iterate_and_advance() guts
is when nothing's left in the iterator, _not_ just when requested
amount is 0. Said guts will do nothing in the latter case anyway;
the problem we tried to deal with in the aforementioned commit is
that when there's nothing left *and* the amount requested is 0,
we might end up deferencing one iovec too many; the value we fetch
from there is discarded in that case, but theoretically it might
oops if the iovec array ends exactly at the end of page with the
next page not mapped.

Bailing out on zero size requested had an unexpected side effect -
zero-length segment in the beginning of iovec array ended up
throwing do_loop_readv_writev() into infinite spin; we do not
advance past the empty segment at all. Reproducer is trivial:
echo '#include <sys/uio.h>' >a.c
echo 'main() {char c; struct iovec v[] = {{&c,0},{&c,1}}; readv(0,v,2);}' >>a.c
cc a.c && ./a.out </proc/uptime

which should end up with the process not hanging. Probably ought to
go into LTP or xfstests...

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

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fold checks into iterate_and_advance()

they are open-coded in all users except iov_iter_advance(), and there
they wouldn't be a bad idea either - as it is, iov_iter_advance(i, 0)
ends up dereferenci

fold checks into iterate_and_advance()

they are open-coded in all users except iov_iter_advance(), and there
they wouldn't be a bad idea either - as it is, iov_iter_advance(i, 0)
ends up dereferencing potentially past the end of iovec array. It
doesn't do anything with the value it reads, and very unlikely to
trigger an oops on dereference, but it is not impossible.

Reported-by: Jiri Slaby <jslaby@suse.cz>
Reported-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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fix the copy vs. map logics in blk_rq_map_user_iov()

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

iov_iter: export import_single_range()

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

iov_iter: constify {csum_and_,}copy_to_iter()

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

VFS: Add iov_iter_fault_in_multipages_readable()

simillar to iov_iter_fault_in_readable() but differs in that it is
not limited to faulting in the first iovec and instead faults in
"bytes" bytes ite

VFS: Add iov_iter_fault_in_multipages_readable()

simillar to iov_iter_fault_in_readable() but differs in that it is
not limited to faulting in the first iovec and instead faults in
"bytes" bytes iterating over the iovecs as necessary.

Also, instead of only faulting in the first and last page of the
range, all pages are faulted in.

This function is needed by NTFS when it does multi page file
writes.

Signed-off-by: Anton Altaparmakov <anton@tuxera.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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saner iov_iter initialization primitives

iovec-backed iov_iter instances are assumed to satisfy several properties:
* no more than UIO_MAXIOV elements in iovec array
* total size of all ranges is

saner iov_iter initialization primitives

iovec-backed iov_iter instances are assumed to satisfy several properties:
* no more than UIO_MAXIOV elements in iovec array
* total size of all ranges is no more than MAX_RW_COUNT
* all ranges pass access_ok().

The problem is, invariants of data structures should be established in the
primitives creating those data structures, not in the code using those
primitives. And iov_iter_init() violates that principle. For a while we
managed to get away with that, but once the use of iov_iter started to
spread, it didn't take long for shit to hit the fan - missed check in
sys_sendto() had introduced a roothole.

We _do_ have primitives for importing and validating iovecs (both native and
compat ones) and those primitives are almost always followed by shoving the
resulting iovec into iov_iter. Life would be considerably simpler (and safer)
if we combined those primitives with initializing iov_iter.

That gives us two new primitives - import_iovec() and compat_import_iovec().
Calling conventions:
iovec = iov_array;
err = import_iovec(direction, uvec, nr_segs,
ARRAY_SIZE(iov_array), &iovec,
&iter);
imports user vector into kernel space (into iov_array if it fits, allocated
if it doesn't fit or if iovec was NULL), validates it and sets iter up to
refer to it. On success 0 is returned and allocated kernel copy (or NULL
if the array had fit into caller-supplied one) is returned via iovec.
On failure all allocations are undone and -E... is returned. If the total
size of ranges exceeds MAX_RW_COUNT, the excess is silently truncated.

compat_import_iovec() expects uvec to be a pointer to user array of compat_iovec;
otherwise it's identical to import_iovec().

Finally, import_single_range() sets iov_iter backed by single-element iovec
covering a user-supplied range -

err = import_single_range(direction, address, size, iovec, &iter);

does validation and sets iter up. Again, size in excess of MAX_RW_COUNT gets
silently truncated.

Next commits will be switching the things up to use of those and reducing
the amount of iov_iter_init() instances.

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

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move iov_iter.c from mm/ to lib/

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

iov_iter_fault_in_readable() should do nothing in xarray case

commit 0e8f0d67401589a141950856902c7d0ec8d9c985 upstream.

... and actually should just check it's given an iovec-backed

iov_iter_fault_in_readable() should do nothing in xarray case

commit 0e8f0d67401589a141950856902c7d0ec8d9c985 upstream.

... and actually should just check it's given an iovec-backed iterator
in the first place.

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

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copy_page_to_iter(): fix ITER_DISCARD case

commit a506abc7b644d71966a75337d5a534f531b3cdc4 upstream.

we need to advance the iterator...

Cc: stable@vger.kernel.org
Signe

copy_page_to_iter(): fix ITER_DISCARD case

commit a506abc7b644d71966a75337d5a534f531b3cdc4 upstream.

we need to advance the iterator...

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

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udp: fix skb_copy_and_csum_datagram with odd segment sizes

commit 52cbd23a119c6ebf40a527e53f3402d2ea38eccb upstream.

When iteratively computing a checksum with csum_block_add, track

udp: fix skb_copy_and_csum_datagram with odd segment sizes

commit 52cbd23a119c6ebf40a527e53f3402d2ea38eccb upstream.

When iteratively computing a checksum with csum_block_add, track the
offset "pos" to correctly rotate in csum_block_add when offset is odd.

The open coded implementation of skb_copy_and_csum_datagram did this.
With the switch to __skb_datagram_iter calling csum_and_copy_to_iter,
pos was reinitialized to 0 on each call.

Bring back the pos by passing it along with the csum to the callback.

Changes v1->v2
- pass csum value, instead of csump pointer (Alexander Duyck)

Link: https://lore.kernel.org/netdev/20210128152353.GB27281@optiplex/
Fixes: 950fcaecd5cc ("datagram: consolidate datagram copy to iter helpers")
Reported-by: Oliver Graute <oliver.graute@gmail.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20210203192952.1849843-1-willemdebruijn.kernel@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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iov_iter: fix the uaccess area in copy_compat_iovec_from_user

[ Upstream commit a959a9782fa87669feeed095ced5d78181a7c02d ]

sizeof needs to be called on the compat pointer, not the n

iov_iter: fix the uaccess area in copy_compat_iovec_from_user

[ Upstream commit a959a9782fa87669feeed095ced5d78181a7c02d ]

sizeof needs to be called on the compat pointer, not the native one.

Fixes: 89cd35c58bc2 ("iov_iter: transparently handle compat iovecs in import_iovec")
Reported-by: David Laight <David.Laight@ACULAB.COM>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>

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lib, uaccess: add failure injection to usercopy functions

To test fault-tolerance of user memory access functions, introduce fault
injection to usercopy functions.

If a failure

lib, uaccess: add failure injection to usercopy functions

To test fault-tolerance of user memory access functions, introduce fault
injection to usercopy functions.

If a failure is expected return either -EFAULT or the total amount of
bytes that were not copied.

Signed-off-by: Albert van der Linde <alinde@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Akinobu Mita <akinobu.mita@gmail.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Marco Elver <elver@google.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Christoph Hellwig <hch@lst.de>
Link: http://lkml.kernel.org/r/20200831171733.955393-3-alinde@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

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Merge branch 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull compat iovec cleanups from Al Viro:
"Christoph's series around import_iovec() and compat vari

Merge branch 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull compat iovec cleanups from Al Viro:
"Christoph's series around import_iovec() and compat variant thereof"

* 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
security/keys: remove compat_keyctl_instantiate_key_iov
mm: remove compat_process_vm_{readv,writev}
fs: remove compat_sys_vmsplice
fs: remove the compat readv/writev syscalls
fs: remove various compat readv/writev helpers
iov_iter: transparently handle compat iovecs in import_iovec
iov_iter: refactor rw_copy_check_uvector and import_iovec
iov_iter: move rw_copy_check_uvector() into lib/iov_iter.c
compat.h: fix a spelling error in <linux/compat.h>

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Merge branch 'work.csum_and_copy' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull copy_and_csum cleanups from Al Viro:
"Saner calling conventions for csum_and_copy_..._us

Merge branch 'work.csum_and_copy' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull copy_and_csum cleanups from Al Viro:
"Saner calling conventions for csum_and_copy_..._user() and friends"

[ Removing 800+ lines of code and cleaning stuff up is good - Linus ]

* 'work.csum_and_copy' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
ppc: propagate the calling conventions change down to csum_partial_copy_generic()
amd64: switch csum_partial_copy_generic() to new calling conventions
sparc64: propagate the calling convention changes down to __csum_partial_copy_...()
xtensa: propagate the calling conventions change down into csum_partial_copy_generic()
mips: propagate the calling convention change down into __csum_partial_copy_..._user()
mips: __csum_partial_copy_kernel() has no users left
mips: csum_and_copy_{to,from}_user() are never called under KERNEL_DS
sparc32: propagate the calling conventions change down to __csum_partial_copy_sparc_generic()
i386: propagate the calling conventions change down to csum_partial_copy_generic()
sh: propage the calling conventions change down to csum_partial_copy_generic()
m68k: get rid of zeroing destination on error in csum_and_copy_from_user()
arm: propagate the calling convention changes down to csum_partial_copy_from_user()
alpha: propagate the calling convention changes down to csum_partial_copy.c helpers
saner calling conventions for csum_and_copy_..._user()
csum_and_copy_..._user(): pass 0xffffffff instead of 0 as initial sum
csum_partial_copy_nocheck(): drop the last argument
unify generic instances of csum_partial_copy_nocheck()
icmp_push_reply(): reorder adding the checksum up
skb_copy_and_csum_bits(): don't bother with the last argument

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