Previous implementation wanted variable order and '(null)' string output
to match the C implementation. The '(null)' string output was a
quirk/bug and so there is no need to carry it forward.
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Garry <john.garry@huawei.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Will Deacon <will@kernel.org>
Cc: Xing Zhengjun <zhengjun.xing@linux.intel.com>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lore.kernel.org/lkml/20220804221816.1802790-3-irogers@google.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Improve type hints to clean up pytype warnings.
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Garry <john.garry@huawei.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Will Deacon <will@kernel.org>
Cc: Xing Zhengjun <zhengjun.xing@linux.intel.com>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lore.kernel.org/lkml/20220804221816.1802790-2-irogers@google.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Switch to new EVP API for detecting libcrypto, as Fedora 36 returns an
error when it encounters the deprecated function MD5_Init() and the others.

The error would be interpreted as missing libcrypto, while in reality it is
not.

Fixes: 6e8ccb4f ("tools/bpf: properly account for libbfd variations")
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: bpf@vger.kernel.org
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: KP Singh <kpsingh@kernel.org>
Cc: llvm@lists.linux.dev
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Nick Terrell <terrelln@fb.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Monnet <quentin@isovalent.com>
Cc: Song Liu <song@kernel.org>
Cc: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20220719170555.2576993-4-roberto.sassu@huawei.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

This reverts commit 10fef869.

Because a proper fix was submitted.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

As the building mechanism is now able to retry detection with different
combinations of linking flags, setting
FEATURE_CHECK_LDFLAGS-disassembler-four-args and
FEATURE_CHECK_LDFLAGS-disassembler-init-styled is not necessary anymore,
so remove it.

Committer notes:

Use the same technique to find the set of bfd-related libraries to link as in:

  3308ffc5016e6136 ("tools, build: Retry detection of bfd-related features")
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andres Freund <andres@anarazel.de>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Nick Terrell <terrelln@fb.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Monnet <quentin@isovalent.com>
Cc: Song Liu <song@kernel.org>
Cc: Stanislav Fomichev <sdf@google.com>
Cc: bpf@vger.kernel.org
Cc: llvm@lists.linux.dev
Link: https://lore.kernel.org/r/20220719170555.2576993-3-roberto.sassu@huawei.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Commit 6e8ccb4f ("tools/bpf: properly account for libbfd variations")
sets the linking flags depending on which flavor of the libbfd feature was
detected.

However, the flavors except libbfd cannot be detected, as they are not in
the feature list.

Complete the list of features to detect by adding libbfd-liberty and
libbfd-liberty-z.

Committer notes:

Adjust conflict with with:

  1e1613f6 ("tools bpftool: Don't display disassembler-four-args feature test")
  600b7b26 ("tools bpftool: Fix compilation error with new binutils")

Fixes: 6e8ccb4f ("tools/bpf: properly account for libbfd variations")
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andres Freund <andres@anarazel.de>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: bpf@vger.kernel.org
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: KP Singh <kpsingh@kernel.org>
Cc: llvm@lists.linux.dev
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Nick Terrell <terrelln@fb.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Monnet <quentin@isovalent.com>
Cc: Song Liu <song@kernel.org>
Cc: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20220719170555.2576993-2-roberto.sassu@huawei.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

While separate features have been defined to determine which linking flags
are required to use libbfd depending on the distribution (libbfd,
libbfd-liberty and libbfd-liberty-z), the same has not been done for other
features requiring linking to libbfd.

For example, disassembler-four-args requires linking to libbfd too, but it
should use the right linking flags. If not all the required ones are
specified, e.g. -liberty, detection will always fail even if the feature is
available.

Instead of creating new features, similarly to libbfd, simply retry
detection with the different set of flags until detection succeeds (or
fails, if the libraries are missing). In this way, feature detection is
transparent for the users of this building mechanism (e.g. perf), and those
users don't have for example to set an appropriate value for the
FEATURE_CHECK_LDFLAGS-disassembler-four-args variable.

The number of retries and features for which the retry mechanism is
implemented is low enough to make the increase in the complexity of
Makefile negligible.

Tested with perf and bpftool on Ubuntu 20.04.4 LTS, Fedora 36 and openSUSE
Tumbleweed.

Committer notes:

Do the retry for disassembler-init-styled as well.
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andres Freund <andres@anarazel.de>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Nick Terrell <terrelln@fb.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Monnet <quentin@isovalent.com>
Cc: Song Liu <song@kernel.org>
Cc: Stanislav Fomichev <sdf@google.com>
Cc: bpf@vger.kernel.org
Cc: llvm@lists.linux.dev
Link: https://lore.kernel.org/r/20220719170555.2576993-1-roberto.sassu@huawei.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Add field checking tests for perf stat JSON output.

Sanity checks the expected number of fields are present, that the
expected keys are present and they have the correct values.

Committer notes:

Had to fix this:

  -               $(INSTALL) tests/shell/lib/*.sh '$(DESTDIR_SQ)$(perfexec_instdir_SQ)/tests/shell/lib' \
  +               $(INSTALL) tests/shell/lib/*.sh '$(DESTDIR_SQ)$(perfexec_instdir_SQ)/tests/shell/lib'; \

Committer testing:

  [root@quaco ~]# perf test json
   90: perf stat JSON output linter                                    : Ok
  [root@quaco ~]# set -o vi
  [root@quaco ~]# perf test -v json
   90: perf stat JSON output linter                                    :
  --- start ---
  test child forked, pid 560794
  Checking json output: no args [Success]
  Checking json output: system wide [Success]
  Checking json output: system wide Checking json output: system wide no aggregation [Success]
  Checking json output: interval [Success]
  Checking json output: event [Success]
  Checking json output: per core [Success]
  Checking json output: per thread [Success]
  Checking json output: per die [Success]
  Checking json output: per node [Success]
  Checking json output: per socket [Success]
  test child finished with 0
  ---- end ----
  perf stat JSON output linter: Ok
  [root@quaco ~]#
Signed-off-by: Claire Jensen <cjense@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alyssa Ross <hi@alyssa.is>
Cc: Claire Jensen <clairej735@gmail.com>
Cc: Florian Fischer <florian.fischer@muhq.space>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Like Xu <likexu@tencent.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sandipan Das <sandipan.das@amd.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Xing Zhengjun <zhengjun.xing@linux.intel.com>
Link: https://lore.kernel.org/r/20220805200105.2020995-3-irogers@google.comSigned-off-by: Ian Rogers <irogers@google.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

CSV output is tricky to format and column layout changes are susceptible
to breaking parsers. New JSON-formatted output has variable names to
identify fields that are consistent and informative, making the output
parseable.

CSV output example:

  1.20,msec,task-clock:u,1204272,100.00,0.697,CPUs utilized
  0,,context-switches:u,1204272,100.00,0.000,/sec
  0,,cpu-migrations:u,1204272,100.00,0.000,/sec
  70,,page-faults:u,1204272,100.00,58.126,K/sec

JSON output example:

  {"counter-value" : "3805.723968", "unit" : "msec", "event" :
  "cpu-clock", "event-runtime" : 3805731510100.00, "pcnt-running"
  : 100.00, "metric-value" : 4.007571, "metric-unit" : "CPUs utilized"}
  {"counter-value" : "6166.000000", "unit" : "", "event" :
  "context-switches", "event-runtime" : 3805723045100.00, "pcnt-running"
  : 100.00, "metric-value" : 1.620191, "metric-unit" : "K/sec"}
  {"counter-value" : "466.000000", "unit" : "", "event" :
  "cpu-migrations", "event-runtime" : 3805727613100.00, "pcnt-running"
  : 100.00, "metric-value" : 122.447136, "metric-unit" : "/sec"}
  {"counter-value" : "208.000000", "unit" : "", "event" :
  "page-faults", "event-runtime" : 3805726799100.00, "pcnt-running"
  : 100.00, "metric-value" : 54.654516, "metric-unit" : "/sec"}

Also added documentation for JSON option.

There is some tidy up of CSV code including a potential memory over run
in the os.nfields set up. To facilitate this an AGGR_MAX value is added.

Committer notes:

Fixed up using PRIu64 to format u64 values, not %lu.

Committer testing:

  ⬢[acme@toolbox perf]$ perf stat -j sleep 1
  {"counter-value" : "0.731750", "unit" : "msec", "event" : "task-clock:u", "event-runtime" : 731750, "pcnt-running" : 100.00, "metric-value" : 0.000731, "metric-unit" : "CPUs utilized"}
  {"counter-value" : "0.000000", "unit" : "", "event" : "context-switches:u", "event-runtime" : 731750, "pcnt-running" : 100.00, "metric-value" : 0.000000, "metric-unit" : "/sec"}
  {"counter-value" : "0.000000", "unit" : "", "event" : "cpu-migrations:u", "event-runtime" : 731750, "pcnt-running" : 100.00, "metric-value" : 0.000000, "metric-unit" : "/sec"}
  {"counter-value" : "75.000000", "unit" : "", "event" : "page-faults:u", "event-runtime" : 731750, "pcnt-running" : 100.00, "metric-value" : 102.494021, "metric-unit" : "K/sec"}
  {"counter-value" : "578765.000000", "unit" : "", "event" : "cycles:u", "event-runtime" : 379366, "pcnt-running" : 49.00, "metric-value" : 0.790933, "metric-unit" : "GHz"}
  {"counter-value" : "1298.000000", "unit" : "", "event" : "stalled-cycles-frontend:u", "event-runtime" : 768020, "pcnt-running" : 100.00, "metric-value" : 0.224271, "metric-unit" : "frontend cycles idle"}
  {"counter-value" : "21984.000000", "unit" : "", "event" : "stalled-cycles-backend:u", "event-runtime" : 768020, "pcnt-running" : 100.00, "metric-value" : 3.798433, "metric-unit" : "backend cycles idle"}
  {"counter-value" : "468197.000000", "unit" : "", "event" : "instructions:u", "event-runtime" : 768020, "pcnt-running" : 100.00, "metric-value" : 0.808959, "metric-unit" : "insn per cycle"}
  {"metric-value" : 0.046955, "metric-unit" : "stalled cycles per insn"}
  {"counter-value" : "103335.000000", "unit" : "", "event" : "branches:u", "event-runtime" : 768020, "pcnt-running" : 100.00, "metric-value" : 141.216262, "metric-unit" : "M/sec"}
  {"counter-value" : "2381.000000", "unit" : "", "event" : "branch-misses:u", "event-runtime" : 388654, "pcnt-running" : 50.00, "metric-value" : 2.304156, "metric-unit" : "of all branches"}
  ⬢[acme@toolbox perf]$
Signed-off-by: Claire Jensen <cjense@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alyssa Ross <hi@alyssa.is>
Cc: Claire Jensen <clairej735@gmail.com>
Cc: Florian Fischer <florian.fischer@muhq.space>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Like Xu <likexu@tencent.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sandipan Das <sandipan.das@amd.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Xing Zhengjun <zhengjun.xing@linux.intel.com>
Link: https://lore.kernel.org/r/20220805200105.2020995-2-irogers@google.comSigned-off-by: Ian Rogers <irogers@google.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Pull ksmbd updates from Steve French:

 - fixes for memory access bugs (out of bounds access, oops, leak)

 - multichannel fixes

 - session disconnect performance improvement, and session register
   improvement

 - cleanup

* tag '5.20-rc-ksmbd-server-fixes' of git://git.samba.org/ksmbd:
  ksmbd: fix heap-based overflow in set_ntacl_dacl()
  ksmbd: prevent out of bound read for SMB2_TREE_CONNNECT
  ksmbd: prevent out of bound read for SMB2_WRITE
  ksmbd: fix use-after-free bug in smb2_tree_disconect
  ksmbd: fix memory leak in smb2_handle_negotiate
  ksmbd: fix racy issue while destroying session on multichannel
  ksmbd: use wait_event instead of schedule_timeout()
  ksmbd: fix kernel oops from idr_remove()
  ksmbd: add channel rwlock
  ksmbd: replace sessions list in connection with xarray
  MAINTAINERS: ksmbd: add entry for documentation
  ksmbd: remove unused ksmbd_share_configs_cleanup function

Pull more iov_iter updates from Al Viro:

 - more new_sync_{read,write}() speedups - ITER_UBUF introduction

 - ITER_PIPE cleanups

 - unification of iov_iter_get_pages/iov_iter_get_pages_alloc and
   switching them to advancing semantics

 - making ITER_PIPE take high-order pages without splitting them

 - handling copy_page_from_iter() for high-order pages properly

* tag 'pull-work.iov_iter-rebased' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (32 commits)
  fix copy_page_from_iter() for compound destinations
  hugetlbfs: copy_page_to_iter() can deal with compound pages
  copy_page_to_iter(): don't split high-order page in case of ITER_PIPE
  expand those iov_iter_advance()...
  pipe_get_pages(): switch to append_pipe()
  get rid of non-advancing variants
  ceph: switch the last caller of iov_iter_get_pages_alloc()
  9p: convert to advancing variant of iov_iter_get_pages_alloc()
  af_alg_make_sg(): switch to advancing variant of iov_iter_get_pages()
  iter_to_pipe(): switch to advancing variant of iov_iter_get_pages()
  block: convert to advancing variants of iov_iter_get_pages{,_alloc}()
  iov_iter: advancing variants of iov_iter_get_pages{,_alloc}()
  iov_iter: saner helper for page array allocation
  fold __pipe_get_pages() into pipe_get_pages()
  ITER_XARRAY: don't open-code DIV_ROUND_UP()
  unify the rest of iov_iter_get_pages()/iov_iter_get_pages_alloc() guts
  unify xarray_get_pages() and xarray_get_pages_alloc()
  unify pipe_get_pages() and pipe_get_pages_alloc()
  iov_iter_get_pages(): sanity-check arguments
  iov_iter_get_pages_alloc(): lift freeing pages array on failure exits into wrapper
  ...

had been broken for ITER_BVEC et.al. since ever (OK, v3.17 when
ITER_BVEC had first appeared)...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

... since April 2021
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

... just shove it into one pipe_buffer.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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

now that we are advancing the iterator, there's no need to
treat the first page separately - just call append_pipe()
in a loop.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

mechanical change; will be further massaged in subsequent commits
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

here nothing even looks at the iov_iter after the call, so we couldn't
care less whether it advances or not.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

that one is somewhat clumsier than usual and needs serious testing.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

... and adjust the callers
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

... and untangle the cleanup on failure to add into pipe.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

... doing revert if we end up not using some pages
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Most of the users immediately follow successful iov_iter_get_pages()
with advancing by the amount it had returned.

Provide inline wrappers doing that, convert trivial open-coded
uses of those.

BTW, iov_iter_get_pages() never returns more than it had been asked
to; such checks in cifs ought to be removed someday...
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

All call sites of get_pages_array() are essenitally identical now.
Replace with common helper...

Returns number of slots available in resulting array or 0 on OOM;
it's up to the caller to make sure it doesn't ask to zero-entry
array (i.e. neither maxpages nor size are allowed to be zero).
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

... and don't mangle maxsize there - turn the loop into counting
one instead.  Easier to see that we won't run out of array that
way.  Note that special treatment of the partial buffer in that
thing is an artifact of the non-advancing semantics of
iov_iter_get_pages() - if not for that, it would be append_pipe(),
same as the body of the loop that follows it.  IOW, once we make
iov_iter_get_pages() advancing, the whole thing will turn into
	calculate how many pages do we want
	allocate an array (if needed)
	call append_pipe() that many times.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

same as for pipes and xarrays; after that iov_iter_get_pages() becomes
a wrapper for __iov_iter_get_pages_alloc().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

same as for pipes
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

	The differences between those two are
* pipe_get_pages() gets a non-NULL struct page ** value pointing to
preallocated array + array size.
* pipe_get_pages_alloc() gets an address of struct page ** variable that
contains NULL, allocates the array and (on success) stores its address in
that variable.

	Not hard to combine - always pass struct page ***, have
the previous pipe_get_pages_alloc() caller pass ~0U as cap for
array size.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

zero maxpages is bogus, but best treated as "just return 0";
NULL pages, OTOH, should be treated as a hard bug.

get rid of now completely useless checks in xarray_get_pages{,_alloc}().
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Incidentally, ITER_XARRAY did *not* free the sucker in case when
iter_xarray_populate_pages() returned 0...
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

All their callers are next to each other; all of them
want the total amount of pages and, possibly, the
offset in the partial final buffer.

Combine into a new helper (pipe_npages()), fix the
bogosity in pipe_space_for_user(), while we are at it.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

We often need to find whether the last buffer is anon or not, and
currently it's rather clumsy:
	check if ->iov_offset is non-zero (i.e. that pipe is not empty)
	if so, get the corresponding pipe_buffer and check its ->ops
	if it's &default_pipe_buf_ops, we have an anon buffer.

Let's replace the use of ->iov_offset (which is nowhere near similar to
its role for other flavours) with signed field (->last_offset), with
the following rules:
	empty, no buffers occupied:		0
	anon, with bytes up to N-1 filled:	N
	zero-copy, with bytes up to N-1 filled:	-N

That way abs(i->last_offset) is equal to what used to be in i->iov_offset
and empty vs. anon vs. zero-copy can be distinguished by the sign of
i->last_offset.

	Checks for "should we extend the last buffer or should we start
a new one?" become easier to follow that way.

	Note that most of the operations can only be done in a sane
state - i.e. when the pipe has nothing past the current position of
iterator.  About the only thing that could be done outside of that
state is iov_iter_advance(), which transitions to the sane state by
truncating the pipe.  There are only two cases where we leave the
sane state:
	1) iov_iter_get_pages()/iov_iter_get_pages_alloc().  Will be
dealt with later, when we make get_pages advancing - the callers are
actually happier that way.
	2) iov_iter copied, then something is put into the copy.  Since
they share the underlying pipe, the original gets behind.  When we
decide that we are done with the copy (original is not usable until then)
we advance the original.  direct_io used to be done that way; nowadays
it operates on the original and we do iov_iter_revert() to discard
the excessive data.  At the moment there's nothing in the kernel that
could do that to ITER_PIPE iterators, so this reason for insane state
is theoretical right now.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Fold pipe_truncate() into it, clean up.  We can release buffers
in the same loop where we walk backwards to the iterator beginning
looking for the place where the new position will be.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

instead of setting ->iov_offset for new position and calling
pipe_truncate() to adjust ->len of the last buffer and discard
everything after it, adjust ->len at the same time we set ->iov_offset
and use pipe_discard_from() to deal with buffers past that.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

it's only used to get to the partial buffer we can add to,
and that's always the last one, i.e. pipe->head - 1.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

	Expand the only remaining call of push_pipe() (in
__pipe_get_pages()), combine it with the page-collecting loop there.

Note that the only reason it's not a loop doing append_pipe() is
that append_pipe() is advancing, while iov_iter_get_pages() is not.
As soon as it switches to saner semantics, this thing will switch
to using append_pipe().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

New helper: append_pipe().  Extends the last buffer if possible,
allocates a new one otherwise.  Returns page and offset in it
on success, NULL on failure.  iov_iter is advanced past the
data we've got.

Use that instead of push_pipe() in copy-to-pipe primitives;
they get simpler that way.  Handling of short copy (in "mc" one)
is done simply by iov_iter_revert() - iov_iter is in consistent
state after that one, so we can use that.

[Fix for braino caught by Liu Xinpeng <liuxp11@chinatelecom.cn> folded in]
[another braino fix, this time in copy_pipe_to_iter() and pipe_zero();
caught by testcase from Hugh Dickins]
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

There are only two kinds of pipe_buffer in the area used by ITER_PIPE.

1) anonymous - copy_to_iter() et.al. end up creating those and copying
data there.  They have zero ->offset, and their ->ops points to
default_pipe_page_ops.

2) zero-copy ones - those come from copy_page_to_iter(), and page
comes from caller.  ->offset is also caller-supplied - it might be
non-zero.  ->ops points to page_cache_pipe_buf_ops.

Move creation and insertion of those into helpers - push_anon(pipe, size)
and push_page(pipe, page, offset, size) resp., separating them from
the "could we avoid creating a new buffer by merging with the current
head?" logics.
Acked-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

pipe_buffer instances of a pipe are organized as a ring buffer,
with power-of-2 size.  Indices are kept *not* reduced modulo ring
size, so the buffer refered to by index N is
	pipe->bufs[N & (pipe->ring_size - 1)].

Ring size can change over the lifetime of a pipe, but not while
the pipe is locked.  So for any iov_iter primitives it's a constant.
Original conversion of pipes to this layout went overboard trying
to microoptimize that - calculating pipe->ring_size - 1, storing
it in a local variable and using through the function.  In some
cases it might be warranted, but most of the times it only
obfuscates what's going on in there.

Introduce a helper (pipe_buf(pipe, N)) that would encapsulate
that and use it in the obvious cases.  More will follow...
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>