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	Thu, 19 Nov 2015 10:33:04 -0500
From: Jeff Moyer <jmoyer@redhat.com>
To: Jan Kara <jack@suse.cz>
Cc: Avi Kivity <avi@scylladb.com>, xfs@oss.sgi.com,
	linux-aio@kvack.org, Steven Whitehouse <swhiteho@redhat.com>,
	linux-fsdevel@vger.kernel.org
Subject: Re: AIO read returns negative number for bytes read
References: <564883BD.8070607@scylladb.com>
	<x497flhsq1c.fsf@segfault.boston.devel.redhat.com>
	<564B2303.7000902@scylladb.com> <20151119153004.GB25804@quack.suse.cz>
Date: Thu, 19 Nov 2015 10:33:03 -0500
In-Reply-To: <20151119153004.GB25804@quack.suse.cz> (Jan Kara's message of
	"Thu, 19 Nov 2015 16:30:04 +0100")
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Jan Kara <jack@suse.cz> writes:

> Can you please post the reproduce here as well? I couldn't easily find it
> with google.

Here it is, Jan.

-Jeff

#define _GNU_SOURCE

#include <libaio.h>
#include <assert.h>
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
#include <sys/stat.h>
#include <fcntl.h>

int main(int ac, char** av) {
  int fd;
  char* buf;
  io_context_t ioc = NULL;
  int r;
  struct iocb iocb;
  struct iocb *iocbp[1];
  struct io_event ioev;

  buf = aligned_alloc(4096, 4096*4);
  assert(buf);
  r = io_setup(1, &ioc);
  assert(r == 0);
  fd = open("tmp.tmp", O_RDWR | O_CREAT | O_DIRECT, 0600);
  assert(fd >= 0);
  io_prep_pwrite(&iocb, fd, buf, 4096*4, 0);
  iocbp[0] = &iocb;
  r = io_submit(ioc, 1, iocbp);
  assert(r == 1);
  r = io_getevents(ioc, 1, 1, &ioev, NULL);
  assert(r == 1);
  assert(ioev.res == 4*4096);
  ftruncate(fd, 13002);
  io_prep_pread(&iocb, fd, buf, 8192, 13312);
  r = io_submit(ioc, 1, iocbp);
  assert(r == 1);
  r = io_getevents(ioc, 1, 1, &ioev, NULL);
  assert(r == 1);
  printf("read result: %d\n", (int)ioev.res);
  return 0;
}