On Tue, Jul 10, 2018 at 04:09:42PM -0600, Ross Zwisler wrote: > This adds a regression test for the following series: > > https://lists.01.org/pipermail/linux-nvdimm/2018-July/016842.html > > which adds synchronization between DAX DMA in ext4 and truncate/hole-punch. > The intention of the test is to test those specific changes, but it runs > fine both with XFS and without DAX so I've put it in the generic tests > instead of ext4 and not restricted it to only DAX configurations. > > When run with v4.18-rc4 + DAX + ext4, this test will hit the following > WARN_ON_ONCE() in dax_disassociate_entry(): > > WARN_ON_ONCE(trunc && page_ref_count(page) > 1); > > If you change this to a WARN_ON() instead, you can see that each of the > four paths being exercised in this test hits that condition many times in > the one second that the subtest is being run. > > Signed-off-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx> > --- > .gitignore | 1 + > src/Makefile | 2 +- > src/t_mmap_collision.c | 235 +++++++++++++++++++++++++++++++++++++++++++++++++ > tests/generic/999 | 53 +++++++++++ > tests/generic/999.out | 2 + > tests/generic/group | 1 + > 6 files changed, 293 insertions(+), 1 deletion(-) > create mode 100644 src/t_mmap_collision.c > create mode 100755 tests/generic/999 > create mode 100644 tests/generic/999.out > > diff --git a/.gitignore b/.gitignore > index efc73a7c..ea1aac8a 100644 > --- a/.gitignore > +++ b/.gitignore > @@ -125,6 +125,7 @@ > /src/t_holes > /src/t_immutable > /src/t_locks_execve > +/src/t_mmap_collision > /src/t_mmap_cow_race > /src/t_mmap_dio > /src/t_mmap_fallocate > diff --git a/src/Makefile b/src/Makefile > index 9e971bcc..41826585 100644 > --- a/src/Makefile > +++ b/src/Makefile > @@ -16,7 +16,7 @@ TARGETS = dirstress fill fill2 getpagesize holes lstat64 \ > holetest t_truncate_self t_mmap_dio af_unix t_mmap_stale_pmd \ > t_mmap_cow_race t_mmap_fallocate fsync-err t_mmap_write_ro \ > t_ext4_dax_journal_corruption t_ext4_dax_inline_corruption \ > - t_ofd_locks t_locks_execve > + t_ofd_locks t_locks_execve t_mmap_collision > > LINUX_TARGETS = xfsctl bstat t_mtab getdevicesize preallo_rw_pattern_reader \ > preallo_rw_pattern_writer ftrunc trunc fs_perms testx looptest \ > diff --git a/src/t_mmap_collision.c b/src/t_mmap_collision.c > new file mode 100644 > index 00000000..5f58d858 > --- /dev/null > +++ b/src/t_mmap_collision.c > @@ -0,0 +1,235 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Copyright (c) 2018 Intel Corporation. > + * > + * As of kernel version 4.18-rc4, Linux has an issue with ext4+DAX where DMA > + * and direct I/O operations aren't synchronized with respect to operations > + * which can change the block mappings of an inode. This means that we can > + * schedule an I/O for an inode and have the block mapping for that inode > + * change before the I/O is actually complete. So, blocks which were once > + * allocated to a given inode and then freed could still have I/O operations > + * happening to them. If these blocks have also been reallocated to a > + * different inode, this interaction can lead to data corruption. > + * > + * This test exercises four of the paths in ext4 which hit this issue. > + */ > +#include <errno.h> > +#include <fcntl.h> > +#include <pthread.h> > +#include <stdbool.h> > +#include <stdio.h> > +#include <stdlib.h> > +#include <string.h> > +#include <sys/mman.h> > +#include <sys/stat.h> > +#include <sys/types.h> > +#include <unistd.h> > + > +#define PAGE(a) ((a)*0x1000) > +#define FILE_SIZE PAGE(4) > + > +void *dax_data; > +int nodax_fd; > +int dax_fd; > +bool done; > + > +#define err_exit(op) \ > +{ \ > + fprintf(stderr, "%s %s: %s\n", __func__, op, strerror(errno)); \ > + exit(1); \ > +} \ > + > +#if defined(FALLOC_FL_PUNCH_HOLE) && defined(FALLOC_FL_KEEP_SIZE) Yeah, dropping '_require_xfs_io_command "falloc"' etc is fine, as long as we do the check in c code. But this check doesn't seem sufficient, it's possible that the system has the flags defined but the filesystem doesn't support such operations. e.g. I got failures like below on btrfs +collapse_range_fn fallocate 2: Operation not supported +collapse_range_fn fallocate 2: Operation not supported and similar failure on NFS +main dax_fd fallocate: Operation not supported IMHO, using _require_xfs_io_command is much easier :) (Though we only need filesystems to support such operations not xfs_io, I don't think we'll lose much test coverage, as it's unlikely that filesystems have fallocate/collapse/punch/zero support but xfs_io doesn't.) > +void punch_hole_fn(void *ptr) > +{ > + ssize_t read; > + int rc; > + > + while (!done) { > + read = 0; > + > + do { > + rc = pread(nodax_fd, dax_data + read, FILE_SIZE - read, > + read); > + if (rc > 0) > + read += rc; > + } while (rc > 0); > + > + if (read != FILE_SIZE || rc != 0) > + err_exit("pread"); > + > + rc = fallocate(dax_fd, > + FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, > + 0, FILE_SIZE); > + if (rc < 0) > + err_exit("fallocate"); > + > + usleep(rand() % 1000); > + } > +} > +#else > +void punch_hole_fn(void *ptr) { } > +#endif > + > +#if defined(FALLOC_FL_ZERO_RANGE) && defined(FALLOC_FL_KEEP_SIZE) > +void zero_range_fn(void *ptr) > +{ > + ssize_t read; > + int rc; > + > + while (!done) { > + read = 0; > + > + do { > + rc = pread(nodax_fd, dax_data + read, FILE_SIZE - read, > + read); > + if (rc > 0) > + read += rc; > + } while (rc > 0); > + > + if (read != FILE_SIZE || rc != 0) > + err_exit("pread"); > + > + rc = fallocate(dax_fd, > + FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE, > + 0, FILE_SIZE); > + if (rc < 0) > + err_exit("fallocate"); > + > + usleep(rand() % 1000); > + } > +} > +#else > +void zero_range_fn(void *ptr) { } > +#endif > + > +void truncate_down_fn(void *ptr) > +{ > + ssize_t read; > + int rc; > + > + while (!done) { > + read = 0; > + > + if (ftruncate(dax_fd, 0) < 0) > + err_exit("ftruncate"); > + if (fallocate(dax_fd, 0, 0, FILE_SIZE) < 0) > + err_exit("fallocate"); > + > + do { > + rc = pread(nodax_fd, dax_data + read, FILE_SIZE - read, > + read); > + if (rc > 0) > + read += rc; > + } while (rc > 0); > + > + /* > + * For this test we ignore errors from pread(). These errors > + * can happen if we try and read while the other thread has > + * made the file size 0. > + */ > + > + usleep(rand() % 1000); > + } > +} > + > +#ifdef FALLOC_FL_COLLAPSE_RANGE > +void collapse_range_fn(void *ptr) > +{ > + ssize_t read; > + int rc; > + > + while (!done) { > + read = 0; > + > + if (fallocate(dax_fd, 0, 0, FILE_SIZE) < 0) > + err_exit("fallocate 1"); > + if (fallocate(dax_fd, FALLOC_FL_COLLAPSE_RANGE, 0, PAGE(1)) < 0) > + err_exit("fallocate 2"); > + if (fallocate(dax_fd, 0, 0, FILE_SIZE) < 0) > + err_exit("fallocate 3"); > + > + do { > + rc = pread(nodax_fd, dax_data + read, FILE_SIZE - read, > + read); > + if (rc > 0) > + read += rc; > + } while (rc > 0); > + > + /* For this test we ignore errors from pread. */ > + > + usleep(rand() % 1000); > + } > +} > +#else > +void collapse_range_fn(void *ptr) { } > +#endif > + > +void run_test(void (*test_fn)(void *)) > +{ > + const int NUM_THREADS = 2; > + pthread_t worker_thread[NUM_THREADS]; > + int i; > + > + done = 0; > + for (i = 0; i < NUM_THREADS; i++) > + pthread_create(&worker_thread[i], NULL, (void*)test_fn, NULL); > + > + sleep(1); > + done = 1; > + > + for (i = 0; i < NUM_THREADS; i++) > + pthread_join(worker_thread[i], NULL); > +} > + > +int main(int argc, char *argv[]) > +{ > + int err; > + > + if (argc != 3) { > + printf("Usage: %s <dax file> <non-dax file>\n", > + basename(argv[0])); > + exit(0); > + } > + > + dax_fd = open(argv[1], O_RDWR|O_CREAT, S_IRUSR|S_IWUSR); > + if (dax_fd < 0) > + err_exit("dax_fd open"); > + > + nodax_fd = open(argv[2], O_RDWR|O_CREAT|O_DIRECT, S_IRUSR|S_IWUSR); > + if (nodax_fd < 0) > + err_exit("nodax_fd open"); > + > + if (ftruncate(dax_fd, 0) < 0) > + err_exit("dax_fd ftruncate"); > + if (fallocate(dax_fd, 0, 0, FILE_SIZE) < 0) > + err_exit("dax_fd fallocate"); > + > + if (ftruncate(nodax_fd, 0) < 0) > + err_exit("nodax_fd ftruncate"); > + if (fallocate(nodax_fd, 0, 0, FILE_SIZE) < 0) > + err_exit("nodax_fd fallocate"); > + > + dax_data = mmap(NULL, FILE_SIZE, PROT_READ|PROT_WRITE, MAP_SHARED, > + dax_fd, 0); > + if (dax_data == MAP_FAILED) > + err_exit("mmap"); > + > + run_test(&punch_hole_fn); > + run_test(&zero_range_fn); > + run_test(&truncate_down_fn); > + run_test(&collapse_range_fn); > + > + if (munmap(dax_data, FILE_SIZE) != 0) > + err_exit("munmap"); > + > + err = close(dax_fd); > + if (err < 0) > + err_exit("dax_fd close"); > + > + err = close(nodax_fd); > + if (err < 0) > + err_exit("nodax_fd close"); > + > + return 0; > +} > diff --git a/tests/generic/999 b/tests/generic/999 > new file mode 100755 > index 00000000..0db824fb > --- /dev/null > +++ b/tests/generic/999 > @@ -0,0 +1,53 @@ > +#! /bin/bash > +# SPDX-License-Identifier: GPL-2.0 > +# Copyright (c) 2018 Intel Corporation. All Rights Reserved. > +# > +# FS QA Test generic/999 > +# > +# This is a regression test for kernel patch: > +# ext4: handle layout changes to pinned DAX mapping Better to have detailed test description here too. > +# > +seq=`basename $0` > +seqres=$RESULT_DIR/$seq > +echo "QA output created by $seq" > + > +here=`pwd` > +tmp=/tmp/$$ > +status=1 # failure is the default! > +trap "_cleanup; exit \$status" 0 1 2 3 15 > + > +_cleanup() > +{ > + cd / > + rm -f $tmp.* > +} > + > +# get standard environment, filters and checks > +. ./common/rc > +. ./common/filter > + > +# remove previous $seqres.full before test > +rm -f $seqres.full > + > +# Modify as appropriate. > +_supported_fs generic > +_supported_os Linux > +_require_test > +_require_test_program "t_mmap_collision" > + > +# To get the failure we turn off DAX on our SCRATCH_MNT so we can get O_DIRECT > +# behavior. We will continue to use unmodified mount options for the test > +# TEST_DIR. The failures fixed by the above mentioned kernel patch trigger > +# when those mount options include "-o dax", but the test runs fine without > +# that option so we don't require it. > +export MOUNT_OPTIONS="" > +_scratch_unmount >> $seqres.full 2>&1 > +_scratch_mount >> $seqres.full 2>&1 Need to _require_scratch first and do _scratch_mkfs, then _scratch_mount. e.g. _require_scratch ... _scratch_mkfs >> $seqres.full # <comments on unseting MOUNT_OPTIONS here> export MOUNT_OPTIONS="" _scratch_mount Thanks, Eryu > + > +# real QA test starts here > +$here/src/t_mmap_collision $TEST_DIR/testfile $SCRATCH_MNT/testfile > + > +# success, all done > +echo "Silence is golden" > +status=0 > +exit > diff --git a/tests/generic/999.out b/tests/generic/999.out > new file mode 100644 > index 00000000..3b276ca8 > --- /dev/null > +++ b/tests/generic/999.out > @@ -0,0 +1,2 @@ > +QA output created by 999 > +Silence is golden > diff --git a/tests/generic/group b/tests/generic/group > index b2a093f4..71f5c945 100644 > --- a/tests/generic/group > +++ b/tests/generic/group > @@ -502,3 +502,4 @@ > 497 auto quick swap collapse > 498 auto quick log > 499 auto quick rw collapse zero > +999 auto quick dax punch collapse zero > -- > 2.14.4 >
