From: Darrick J. Wong <darrick.wong@xxxxxxxxxx> Dave Chinner reports[1] that an appending AIO DIO write to the second block of a zero-length file and an fallocate request to the first block of the same file can race to set isize, with the user-visible end result that the file size is set incorrectly to one block long. Write a small test to reproduce the results. [1] https://lore.kernel.org/linux-xfs/20191029100342.GA41131@bfoster/T/ Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx> --- .../aio-dio-append-write-fallocate-race.c | 212 ++++++++++++++++++++ tests/generic/722 | 44 ++++ tests/generic/722.out | 2 tests/generic/group | 1 4 files changed, 259 insertions(+) create mode 100644 src/aio-dio-regress/aio-dio-append-write-fallocate-race.c create mode 100755 tests/generic/722 create mode 100644 tests/generic/722.out diff --git a/src/aio-dio-regress/aio-dio-append-write-fallocate-race.c b/src/aio-dio-regress/aio-dio-append-write-fallocate-race.c new file mode 100644 index 00000000..091b047d --- /dev/null +++ b/src/aio-dio-regress/aio-dio-append-write-fallocate-race.c @@ -0,0 +1,212 @@ +// SPDX-License-Identifier: GPL-2.0-or-newer +/* + * Copyright (c) 2019 Oracle. + * All Rights Reserved. + * + * Race appending aio dio and fallocate to make sure we get the correct file + * size afterwards. + */ +#include <stdio.h> +#include <pthread.h> +#include <sys/types.h> +#include <sys/stat.h> +#include <fcntl.h> +#include <unistd.h> +#include <string.h> +#include <errno.h> +#include <libaio.h> +#include <stdlib.h> +#include <stdbool.h> +#include <limits.h> + +static int fd; +static int blocksize; + +static void * +falloc_thread( + void *p) +{ + int ret; + + ret = fallocate(fd, 0, 0, blocksize); + if (ret) + perror("falloc"); + + return NULL; +} + +static int +test( + const char *fname, + unsigned int iteration, + unsigned int *passed) +{ + struct stat sbuf; + pthread_t thread; + io_context_t ioctx = 0; + struct iocb iocb; + struct iocb *iocbp = &iocb; + struct io_event event; + char *buf; + bool wait_thread = false; + int ret; + + /* Truncate file, allocate resources for doing IO. */ + fd = open(fname, O_DIRECT | O_RDWR | O_TRUNC | O_CREAT, 0644); + if (fd < 0) { + perror(fname); + return -1; + } + + ret = fstat(fd, &sbuf); + if (ret) { + perror(fname); + goto out; + } + blocksize = sbuf.st_blksize; + + ret = posix_memalign((void **)&buf, blocksize, blocksize); + if (ret) { + errno = ret; + perror("buffer"); + goto out; + } + memset(buf, 'X', blocksize); + memset(&event, 0, sizeof(event)); + + ret = io_queue_init(1, &ioctx); + if (ret) { + errno = -ret; + perror("io_queue_init"); + goto out_buf; + } + + /* + * Set ourselves up to race fallocate(0..blocksize) with aio dio + * pwrite(blocksize..blocksize * 2). This /should/ give us a file + * with length (2 * blocksize). + */ + io_prep_pwrite(&iocb, fd, buf, blocksize, blocksize); + + ret = pthread_create(&thread, NULL, falloc_thread, NULL); + if (ret) { + errno = ret; + perror("pthread"); + goto out_io; + } + wait_thread = true; + + ret = io_submit(ioctx, 1, &iocbp); + if (ret != 1) { + errno = -ret; + perror("io_submit"); + goto out_join; + } + + ret = io_getevents(ioctx, 1, 1, &event, NULL); + if (ret != 1) { + errno = -ret; + perror("io_getevents"); + goto out_join; + } + + if (event.res < 0) { + errno = -event.res; + perror("io_event.res"); + goto out_join; + } + + if (event.res2 < 0) { + errno = -event.res2; + perror("io_event.res2"); + goto out_join; + } + + wait_thread = false; + ret = pthread_join(thread, NULL); + if (ret) { + errno = ret; + perror("join"); + goto out_io; + } + + /* Make sure we actually got a file of size (2 * blocksize). */ + ret = fstat(fd, &sbuf); + if (ret) { + perror(fname); + goto out_buf; + } + + if (sbuf.st_size != 2 * blocksize) { + fprintf(stderr, "[%u]: sbuf.st_size=%llu, expected %llu.\n", + iteration, + (unsigned long long)sbuf.st_size, + (unsigned long long)2 * blocksize); + } else { + printf("[%u]: passed.\n", iteration); + (*passed)++; + } + +out_join: + if (wait_thread) { + ret = pthread_join(thread, NULL); + if (ret) { + errno = ret; + perror("join"); + goto out_io; + } + } +out_io: + ret = io_queue_release(ioctx); + if (ret) { + errno = -ret; + perror("io_queue_release"); + } + +out_buf: + free(buf); +out: + ret = close(fd); + fd = -1; + if (ret) { + perror("close"); + return -1; + } + + return 0; +} + +int main(int argc, char *argv[]) +{ + int ret; + long l; + unsigned int i; + unsigned int passed = 0; + + if (argc != 3) { + printf("Usage: %s filename iterations\n", argv[0]); + return 1; + } + + errno = 0; + l = strtol(argv[2], NULL, 0); + if (errno) { + perror(argv[2]); + return 1; + } + if (l < 1 || l > UINT_MAX) { + fprintf(stderr, "%ld: must be between 1 and %u.\n", + l, UINT_MAX); + return 1; + } + + for (i = 0; i < l; i++) { + ret = test(argv[1], i, &passed); + if (ret) + return 1; + } + + printf("pass rate: %u/%u (%.2f%%)\n", passed, i, 100.0 * passed / i); + + return 0; +} diff --git a/tests/generic/722 b/tests/generic/722 new file mode 100755 index 00000000..307e3b77 --- /dev/null +++ b/tests/generic/722 @@ -0,0 +1,44 @@ +#! /bin/bash +# SPDX-License-Identifier: GPL-2.0-or-later +# Copyright (c) 2019, Oracle and/or its affiliates. All Rights Reserved. +# +# FS QA Test No. 722 +# +# Race an appending aio dio write to the second block of a file while +# simultaneously fallocating to the first block. Make sure that we end up +# with a two-block file. + +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.* $testfile +} + +# get standard environment, filters and checks +. ./common/rc + +# real QA test starts here +_supported_os Linux +_supported_fs generic +_require_aiodio "aiocp" +_require_test +AIO_TEST=$here/src/aio-dio-regress/aio-dio-append-write-fallocate-race + +rm -f $seqres.full + +testfile=$TEST_DIR/test-$seq +$AIO_TEST $testfile 100 >> $seqres.full + +echo Silence is golden. +# success, all done +status=0 +exit diff --git a/tests/generic/722.out b/tests/generic/722.out new file mode 100644 index 00000000..8621a87d --- /dev/null +++ b/tests/generic/722.out @@ -0,0 +1,2 @@ +QA output created by 722 +Silence is golden. diff --git a/tests/generic/group b/tests/generic/group index a252f424..20df0964 100644 --- a/tests/generic/group +++ b/tests/generic/group @@ -591,3 +591,4 @@ 716 dangerous_norepair 720 dangerous_norepair 721 auto quick atime +722 auto quick rw falloc
