test/file-verify: add read verification test

This test attempts to exercise the various paths that a read can take.
We try and trigger incremental reads and loops, by removing page cache
parts of a cached file for reading. In essence, these are the two
types of iterator conditions we want to hit:

1) We get -EAGAIN immediately. This is common for buffered IO when
   the range isn't in page cache.
2) We get a short read, again common for buffered read.

Internally, we have three different mechanisms we want to exercise,
as they can behave a bit differently:

1) Using non-vectored read
1) Using non-vectored registered buffer read
3) Using vectored read, segments that fit in UIO_FASTIOV
4) Using vectored read, segments larger than UIO_FASTIOV

We try and accomplish this by doing reads that hit any of these three
conditions, and then we remove page cache in chunks from a file from
either the front, middle, or end of the file. We do go through all
of these for both buffered and O_DIRECT reads.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

2 files changed, 372 insertions, 0 deletions

diff --git a/test/Makefile b/test/Makefile
index c626f8f..2936469 100644
--- a/test/Makefile
+++ b/test/Makefile
@@ -63,6 +63,7 @@ test_targets += \
 	fallocate \
 	fc2a85cb02ef-test \
 	file-register \
+	file-verify \
 	file-update \
 	files-exit-hang-poll \
 	files-exit-hang-timeout \
@@ -203,6 +204,7 @@ test_srcs := \
 	fallocate.c \
 	fc2a85cb02ef-test.c \
 	file-register.c \
+	file-verify.c \
 	file-update.c \
 	files-exit-hang-poll.c \
 	files-exit-hang-timeout.c \
diff --git a/test/file-verify.c b/test/file-verify.c
new file mode 100644
index 0000000..ffedd87
--- /dev/null
+++ b/test/file-verify.c
@@ -0,0 +1,370 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Description: run various reads tests, verifying data
+ *
+ */
+#include <errno.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <fcntl.h>
+#include <assert.h>
+
+#include "helpers.h"
+#include "liburing.h"
+
+#define FSIZE		128*1024*1024
+#define CHUNK_SIZE	131072
+#define PUNCH_SIZE	32768
+
+/*
+ * 8 because it fits within the on-stack iov, 16 because it's larger than 8
+ */
+#define MIN_VECS	8
+#define MAX_VECS	16
+
+/*
+ * Can be anything, let's just do something for a bit of parallellism
+ */
+#define READ_BATCH	16
+
+/*
+ * Each offset in the file has the offset / sizeof(int) stored for every
+ * sizeof(int) address.
+ */
+static int verify_buf(void *buf, size_t size, off_t off)
+{
+	int i, u_in_buf = size / sizeof(unsigned int);
+	unsigned int *ptr;
+
+	off /= sizeof(unsigned int);
+	ptr = buf;
+	for (i = 0; i < u_in_buf; i++) {
+		if (off != *ptr) {
+			fprintf(stderr, "Found %u, wanted %lu\n", *ptr, off);
+			return 1;
+		}
+		ptr++;
+		off++;
+	}
+
+	return 0;
+}
+
+enum {
+	PUNCH_NONE,
+	PUNCH_FRONT,
+	PUNCH_MIDDLE,
+	PUNCH_END,
+};
+
+/*
+ * For each chunk in file, DONTNEED a start, end, or middle segment of it.
+ * We enter here with the file fully cached every time, either freshly
+ * written or after other reads. This forces (at least) the buffered reads
+ * to be handled incrementally, exercising that path.
+ */
+static int do_punch(int fd)
+{
+	off_t offset = 0;
+	int punch_type;
+
+	while (offset + CHUNK_SIZE <= FSIZE) {
+		off_t punch_off;
+
+		punch_type = rand() % (PUNCH_END + 1);
+		switch (punch_type) {
+		default:
+		case PUNCH_NONE:
+			punch_off = -1; /* gcc... */
+			break;
+		case PUNCH_FRONT:
+			punch_off = offset;
+			break;
+		case PUNCH_MIDDLE:
+			punch_off = offset + PUNCH_SIZE;
+			break;
+		case PUNCH_END:
+			punch_off = offset + CHUNK_SIZE - PUNCH_SIZE;
+			break;
+		}
+
+		offset += CHUNK_SIZE;
+		if (punch_type == PUNCH_NONE)
+			continue;
+		if (posix_fadvise(fd, punch_off, PUNCH_SIZE, POSIX_FADV_DONTNEED) < 0) {
+			perror("posix_fadivse");
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+static int test(struct io_uring *ring, const char *fname, int buffered,
+		int vectored, int small_vecs, int registered)
+{
+	struct iovec vecs[READ_BATCH][MAX_VECS];
+	struct io_uring_cqe *cqe;
+	struct io_uring_sqe *sqe;
+	void *buf[READ_BATCH];
+	int ret, fd, flags;
+	int i, j, nr_vecs;
+	off_t off, voff;
+	size_t left;
+
+	if (registered)
+		assert(!vectored && !small_vecs);
+
+	flags = O_RDONLY;
+	if (!buffered)
+		flags |= O_DIRECT;
+	fd = open(fname, flags);
+	if (fd < 0) {
+		perror("open");
+		return 1;
+	}
+
+	if (do_punch(fd))
+		return 1;
+
+	if (vectored) {
+		if (small_vecs)
+			nr_vecs = MIN_VECS;
+		else
+			nr_vecs = MAX_VECS;
+
+		for (j = 0; j < READ_BATCH; j++) {
+			for (i = 0; i < nr_vecs; i++) {
+				void *ptr;
+
+				t_posix_memalign(&ptr, 4096, CHUNK_SIZE / nr_vecs);
+				vecs[j][i].iov_base = ptr;
+				vecs[j][i].iov_len = CHUNK_SIZE / nr_vecs;
+			}
+		}
+	} else {
+		for (j = 0; j < READ_BATCH; j++)
+			t_posix_memalign(&buf[j], 4096, CHUNK_SIZE);
+		nr_vecs = 0;
+	}
+
+	if (registered) {
+		struct iovec v[READ_BATCH];
+
+		for (i = 0; i < READ_BATCH; i++) {
+			v[i].iov_base = buf[i];
+			v[i].iov_len = CHUNK_SIZE;
+		}
+		ret = io_uring_register_buffers(ring, v, READ_BATCH);
+		if (ret) {
+			fprintf(stderr, "Error buffer reg %d\n", ret);
+			goto err;
+		}
+	}
+
+	i = 0;
+	left = FSIZE;
+	off = 0;
+	while (left) {
+		int pending = 0;
+
+		for (i = 0; i < READ_BATCH; i++) {
+			size_t this = left;
+
+			if (this > CHUNK_SIZE)
+				this = CHUNK_SIZE;
+
+			sqe = io_uring_get_sqe(ring);
+			if (!sqe) {
+				fprintf(stderr, "get sqe failed\n");
+				goto err;
+			}
+
+			if (vectored) {
+				io_uring_prep_readv(sqe, fd, vecs[i], nr_vecs, off);
+			} else {
+				if (registered)
+					io_uring_prep_read_fixed(sqe, fd, buf[i], this, off, i);
+				else
+					io_uring_prep_read(sqe, fd, buf[i], this, off);
+			}
+			sqe->user_data = (off << 32) | i;
+			off += this;
+			left -= this;
+			pending++;
+			if (!left)
+				break;
+		}
+
+		ret = io_uring_submit(ring);
+		if (ret != pending) {
+			fprintf(stderr, "sqe submit failed: %d\n", ret);
+			goto err;
+		}
+
+		for (i = 0; i < pending; i++) {
+			int index;
+
+			ret = io_uring_wait_cqe(ring, &cqe);
+			if (ret < 0) {
+				fprintf(stderr, "wait completion %d\n", ret);
+				goto err;
+			}
+			if (cqe->res < 0) {
+				fprintf(stderr, "bad read %d, read %d\n", cqe->res, i);
+				goto err;
+			}
+			index = cqe->user_data & 0xffffffff;
+			voff = cqe->user_data >> 32;
+			io_uring_cqe_seen(ring, cqe);
+			if (vectored) {
+				for (j = 0; j < nr_vecs; j++) {
+					void *buf = vecs[index][j].iov_base;
+					size_t len = vecs[index][j].iov_len;
+
+					if (verify_buf(buf, len, voff))
+						goto err;
+					voff += len;
+				}
+			} else {
+				if (verify_buf(buf[index], CHUNK_SIZE, voff))
+					goto err;
+			}
+		}
+	}
+
+	ret = 0;
+done:
+	if (registered)
+		io_uring_unregister_buffers(ring);
+	if (vectored) {
+		for (j = 0; j < READ_BATCH; j++)
+			for (i = 0; i < nr_vecs; i++)
+				free(vecs[j][i].iov_base);
+	} else {
+		for (j = 0; j < READ_BATCH; j++)
+			free(buf[j]);
+	}
+	close(fd);
+	return ret;
+err:
+	ret = 1;
+	goto done;
+}
+
+static int fill_pattern(const char *fname)
+{
+	size_t left = FSIZE;
+	unsigned int val, *ptr;
+	void *buf;
+	int fd, i;
+
+	fd = open(fname, O_WRONLY);
+	if (fd < 0) {
+		perror("open");
+		return 1;
+	}
+
+	val = 0;
+	buf = t_malloc(4096);
+	while (left) {
+		int u_in_buf = 4096 / sizeof(val);
+		size_t this = left;
+
+		if (this > 4096)
+			this = 4096;
+		ptr = buf;
+		for (i = 0; i < u_in_buf; i++) {
+			*ptr = val;
+			val++;
+			ptr++;
+		}
+		if (write(fd, buf, 4096) != 4096)
+			return 1;
+		left -= 4096;
+	}
+
+	fsync(fd);
+	close(fd);
+	free(buf);
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	struct io_uring ring;
+	const char *fname;
+	char buf[32];
+	int ret;
+
+	srand(getpid());
+
+	if (argc > 1) {
+		fname = argv[1];
+	} else {
+		sprintf(buf, ".file-verify.%d", getpid());
+		fname = buf;
+		t_create_file(fname, FSIZE);
+	}
+
+	ret = io_uring_queue_init(READ_BATCH, &ring, 0);
+	if (ret) {
+		fprintf(stderr, "ring setup failed: %d\n", ret);
+		goto err;
+	}
+
+	if (fill_pattern(fname))
+		goto err;
+
+	ret = test(&ring, fname, 1, 0, 0, 0);
+	if (ret) {
+		fprintf(stderr, "Buffered novec test failed\n");
+		goto err;
+	}
+	ret = test(&ring, fname, 1, 0, 0, 1);
+	if (ret) {
+		fprintf(stderr, "Buffered novec reg test failed\n");
+		goto err;
+	}
+	ret = test(&ring, fname, 1, 1, 0, 0);
+	if (ret) {
+		fprintf(stderr, "Buffered vec test failed\n");
+		goto err;
+	}
+	ret = test(&ring, fname, 1, 1, 1, 0);
+	if (ret) {
+		fprintf(stderr, "Buffered small vec test failed\n");
+		goto err;
+	}
+
+	ret = test(&ring, fname, 0, 0, 0, 0);
+	if (ret) {
+		fprintf(stderr, "O_DIRECT novec test failed\n");
+		goto err;
+	}
+	ret = test(&ring, fname, 0, 0, 0, 1);
+	if (ret) {
+		fprintf(stderr, "O_DIRECT novec reg test failed\n");
+		goto err;
+	}
+	ret = test(&ring, fname, 0, 1, 0, 0);
+	if (ret) {
+		fprintf(stderr, "O_DIRECT vec test failed\n");
+		goto err;
+	}
+	ret = test(&ring, fname, 0, 1, 1, 0);
+	if (ret) {
+		fprintf(stderr, "O_DIRECT small vec test failed\n");
+		goto err;
+	}
+
+	if (buf == fname)
+		unlink(fname);
+	return 0;
+err:
+	if (buf == fname)
+		unlink(fname);
+	return 1;
+}