Alan Somers a87e0831ab fusefs: WIP fixing writeback cacheing
The current "writeback" cache mode, selected by the
vfs.fusefs.data_cache_mode sysctl, doesn't do writeback cacheing at all.  It
merely goes through the motions of using buf(9), but then writes every
buffer synchronously.  This commit:

* Enables delayed writes when the sysctl is set to writeback cacheing
* Fixes a cache-coherency problem when extending a file whose last page has
  just been written.
* Removes the "sync" mount option, which had been set unconditionally.
* Adjusts some SDT probes
* Adds several new tests that mimic what fsx does but with more control and
  without a real file system.  As I discover failures with fsx, I add
  regression tests to this file.
* Adds a test that ensures we can append to a file without reading any data
  from it.

This change is still incomplete.  Clustered writing is not yet supported,
and there are frequent "panic: vm_fault_hold: fault on nofault entry" panics
that I need to fix.

Sponsored by:	The FreeBSD Foundation
2019-06-11 16:32:33 +00:00

277 lines
7.3 KiB
C++

/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2019 The FreeBSD Foundation
*
* This software was developed by BFF Storage Systems, LLC under sponsorship
* from the FreeBSD Foundation.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
extern "C" {
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
}
#include "mockfs.hh"
#include "utils.hh"
/*
* For testing I/O like fsx does, but deterministically and without a real
* underlying file system
*
* TODO: after fusefs gains the options to select cache mode for each mount
* point, run each of these tests for all cache modes.
*/
using namespace testing;
const char FULLPATH[] = "mountpoint/some_file.txt";
const char RELPATH[] = "some_file.txt";
const uint64_t ino = 42;
class Io: public FuseTest {
public:
int m_backing_fd, m_control_fd, m_test_fd;
Io(): m_backing_fd(-1), m_control_fd(-1) {};
void SetUp()
{
m_backing_fd = open("backing_file", O_RDWR | O_CREAT | O_TRUNC);
if (m_backing_fd < 0)
FAIL() << strerror(errno);
m_control_fd = open("control", O_RDWR | O_CREAT | O_TRUNC);
if (m_control_fd < 0)
FAIL() << strerror(errno);
srandom(22'9'1982); // Seed with my birthday
FuseTest::SetUp();
if (IsSkipped())
return;
expect_lookup(RELPATH, ino, S_IFREG | 0644, 0, 1);
expect_open(ino, 0, 1);
EXPECT_CALL(*m_mock, process(
ResultOf([=](auto in) {
return (in.header.opcode == FUSE_WRITE &&
in.header.nodeid == ino);
}, Eq(true)),
_)
).WillRepeatedly(Invoke(ReturnImmediate([=](auto in, auto& out) {
const char *buf = (const char*)in.body.bytes +
sizeof(struct fuse_write_in);
ssize_t isize = in.body.write.size;
off_t iofs = in.body.write.offset;
ASSERT_EQ(isize, pwrite(m_backing_fd, buf, isize, iofs))
<< strerror(errno);
SET_OUT_HEADER_LEN(out, write);
out.body.write.size = isize;
})));
EXPECT_CALL(*m_mock, process(
ResultOf([=](auto in) {
return (in.header.opcode == FUSE_READ &&
in.header.nodeid == ino);
}, Eq(true)),
_)
).WillRepeatedly(Invoke(ReturnImmediate([=](auto in, auto& out) {
ssize_t isize = in.body.write.size;
off_t iofs = in.body.write.offset;
void *buf = out.body.bytes;
ASSERT_LE(0, pread(m_backing_fd, buf, isize, iofs))
<< strerror(errno);
out.header.len = sizeof(struct fuse_out_header) + isize;
})));
EXPECT_CALL(*m_mock, process(
ResultOf([=](auto in) {
uint32_t valid = FATTR_SIZE | FATTR_FH;
return (in.header.opcode == FUSE_SETATTR &&
in.header.nodeid == ino &&
in.body.setattr.valid == valid);
}, Eq(true)),
_)
).WillRepeatedly(Invoke(ReturnImmediate([=](auto in, auto& out) {
ASSERT_EQ(0, ftruncate(m_backing_fd, in.body.setattr.size))
<< strerror(errno);
SET_OUT_HEADER_LEN(out, attr);
out.body.attr.attr.ino = ino;
out.body.attr.attr.mode = S_IFREG | 0755;
out.body.attr.attr.size = in.body.setattr.size;
out.body.attr.attr_valid = UINT64_MAX;
})));
/* Any test that close()s will send FUSE_FLUSH and FUSE_RELEASE */
EXPECT_CALL(*m_mock, process(
ResultOf([=](auto in) {
return (in.header.opcode == FUSE_FLUSH &&
in.header.nodeid == ino);
}, Eq(true)),
_)
).WillRepeatedly(Invoke(ReturnErrno(0)));
EXPECT_CALL(*m_mock, process(
ResultOf([=](auto in) {
return (in.header.opcode == FUSE_RELEASE &&
in.header.nodeid == ino);
}, Eq(true)),
_)
).WillRepeatedly(Invoke(ReturnErrno(0)));
m_test_fd = open(FULLPATH, O_RDWR );
EXPECT_LE(0, m_test_fd) << strerror(errno);
}
void TearDown()
{
if (m_backing_fd >= 0)
close(m_backing_fd);
if (m_control_fd >= 0)
close(m_control_fd);
FuseTest::TearDown();
/* Deliberately leak test_fd */
}
void do_ftruncate(off_t offs)
{
ASSERT_EQ(0, ftruncate(m_test_fd, offs)) << strerror(errno);
ASSERT_EQ(0, ftruncate(m_control_fd, offs)) << strerror(errno);
}
void do_read(ssize_t size, off_t offs)
{
void *test_buf, *control_buf;
test_buf = malloc(size);
ASSERT_NE(NULL, test_buf) << strerror(errno);
control_buf = malloc(size);
ASSERT_NE(NULL, control_buf) << strerror(errno);
ASSERT_EQ(size, pread(m_test_fd, test_buf, size, offs))
<< strerror(errno);
ASSERT_EQ(size, pread(m_control_fd, control_buf, size, offs))
<< strerror(errno);
ASSERT_EQ(0, memcmp(test_buf, control_buf, size));
free(control_buf);
free(test_buf);
}
void do_write(ssize_t size, off_t offs)
{
char *buf;
long i;
buf = (char*)malloc(size);
ASSERT_NE(NULL, buf) << strerror(errno);
for (i=0; i < size; i++)
buf[i] = random();
ASSERT_EQ(size, pwrite(m_test_fd, buf, size, offs ))
<< strerror(errno);
ASSERT_EQ(size, pwrite(m_control_fd, buf, size, offs))
<< strerror(errno);
}
};
/*
* Extend a file with dirty data in the last page of the last block.
*
* fsx -WR -P /tmp -S8 -N3 fsx.bin
*/
TEST_F(Io, extend_from_dirty_page)
{
off_t wofs = 0x21a0;
ssize_t wsize = 0xf0a8;
off_t rofs = 0xb284;
ssize_t rsize = 0x9b22;
off_t truncsize = 0x28702;
do_write(wsize, wofs);
do_ftruncate(truncsize);
do_read(rsize, rofs);
}
/*
* When writing the last page of a file, it must be written synchronously.
* Otherwise the cached page can become invalid by a subsequent extend
* operation.
*
* fsx -WR -P /tmp -S642 -N3 fsx.bin
*/
TEST_F(Io, last_page)
{
off_t wofs0 = 0x1134f;
ssize_t wsize0 = 0xcc77;
off_t wofs1 = 0x2096a;
ssize_t wsize1 = 0xdfa7;
off_t rofs = 0x1a3aa;
ssize_t rsize = 0xb5b7;
do_write(wsize0, wofs0);
do_write(wsize1, wofs1);
do_read(rsize, rofs);
}
/*
* Read a hole from a block that contains some cached data.
*
* fsx -WR -P /tmp -S55 fsx.bin
*/
TEST_F(Io, read_hole_from_cached_block)
{
off_t wofs = 0x160c5;
ssize_t wsize = 0xa996;
off_t rofs = 0x472e;
ssize_t rsize = 0xd8d5;
do_write(wsize, wofs);
do_read(rsize, rofs);
}
/*
* Reliable panic; I don't yet know why.
* Disabled because it panics.
*
* fsx -WR -P /tmp -S839 -d -N6 fsx.bin
*/
TEST_F(Io, DISABLED_fault_on_nofault_entry)
{
off_t wofs0 = 0x3bad7;
ssize_t wsize0 = 0x4529;
off_t wofs1 = 0xc30d;
ssize_t wsize1 = 0x5f77;
off_t truncsize0 = 0x10916;
off_t rofs = 0xdf17;
ssize_t rsize = 0x29ff;
off_t truncsize1 = 0x152b4;
do_write(wsize0, wofs0);
do_write(wsize1, wofs1);
do_ftruncate(truncsize0);
do_read(rsize, rofs);
do_ftruncate(truncsize1);
close(m_test_fd);
}