qemu-io: add -r option to register I/O buffer
The blk_register_buf() API is an optimization hint that allows some
block drivers to avoid I/O buffer housekeeping or bounce buffers.
Add an -r option to register the I/O buffer so that qemu-io can be used
to test the blk_register_buf() API. The next commit will add a test that
uses the new option.
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Hanna Czenczek <hreitz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20230207203719.242926-4-stefanha@redhat.com>
diff --git a/qemu-io-cmds.c b/qemu-io-cmds.c
index 1f60c23..e7a02f5 100644
--- a/qemu-io-cmds.c
+++ b/qemu-io-cmds.c
@@ -338,7 +338,8 @@
*/
#define MISALIGN_OFFSET 16
-static void *qemu_io_alloc(BlockBackend *blk, size_t len, int pattern)
+static void *qemu_io_alloc(BlockBackend *blk, size_t len, int pattern,
+ bool register_buf)
{
void *buf;
@@ -347,16 +348,24 @@
}
buf = blk_blockalign(blk, len);
memset(buf, pattern, len);
+ if (register_buf) {
+ blk_register_buf(blk, buf, len, &error_abort);
+ }
if (qemuio_misalign) {
buf += MISALIGN_OFFSET;
}
return buf;
}
-static void qemu_io_free(void *p)
+static void qemu_io_free(BlockBackend *blk, void *p, size_t len,
+ bool unregister_buf)
{
if (qemuio_misalign) {
p -= MISALIGN_OFFSET;
+ len += MISALIGN_OFFSET;
+ }
+ if (unregister_buf) {
+ blk_unregister_buf(blk, p, len);
}
qemu_vfree(p);
}
@@ -371,14 +380,16 @@
* @blk - the block backend where the buffer content is going to be written to
* @len - the buffer length
* @file_name - the file to read the content from
+ * @register_buf - call blk_register_buf()
*
* Returns: the buffer pointer on success
* NULL on error
*/
static void *qemu_io_alloc_from_file(BlockBackend *blk, size_t len,
- const char *file_name)
+ const char *file_name, bool register_buf)
{
- char *buf, *buf_origin;
+ size_t alloc_len = len + (qemuio_misalign ? MISALIGN_OFFSET : 0);
+ char *alloc_buf, *buf, *end;
FILE *f = fopen(file_name, "r");
int pattern_len;
@@ -387,19 +398,13 @@
return NULL;
}
- if (qemuio_misalign) {
- len += MISALIGN_OFFSET;
- }
-
- buf_origin = buf = blk_blockalign(blk, len);
+ alloc_buf = buf = blk_blockalign(blk, alloc_len);
if (qemuio_misalign) {
- buf_origin += MISALIGN_OFFSET;
buf += MISALIGN_OFFSET;
- len -= MISALIGN_OFFSET;
}
- pattern_len = fread(buf_origin, 1, len, f);
+ pattern_len = fread(buf, 1, len, f);
if (ferror(f)) {
perror(file_name);
@@ -414,24 +419,23 @@
fclose(f);
f = NULL;
- if (len > pattern_len) {
- len -= pattern_len;
- buf += pattern_len;
-
- while (len > 0) {
- size_t len_to_copy = MIN(pattern_len, len);
-
- memcpy(buf, buf_origin, len_to_copy);
-
- len -= len_to_copy;
- buf += len_to_copy;
- }
+ if (register_buf) {
+ blk_register_buf(blk, alloc_buf, alloc_len, &error_abort);
}
- return buf_origin;
+ end = buf + len;
+ for (char *p = buf + pattern_len; p < end; p += pattern_len) {
+ memcpy(p, buf, MIN(pattern_len, end - p));
+ }
+
+ return buf;
error:
- qemu_io_free(buf_origin);
+ /*
+ * This code path is only taken before blk_register_buf() is called, so
+ * hardcode the qemu_io_free() unregister_buf argument to false.
+ */
+ qemu_io_free(blk, alloc_buf, alloc_len, false);
if (f) {
fclose(f);
}
@@ -490,7 +494,7 @@
*/
static void *
create_iovec(BlockBackend *blk, QEMUIOVector *qiov, char **argv, int nr_iov,
- int pattern)
+ int pattern, bool register_buf)
{
size_t *sizes = g_new0(size_t, nr_iov);
size_t count = 0;
@@ -526,7 +530,7 @@
qemu_iovec_init(qiov, nr_iov);
- buf = p = qemu_io_alloc(blk, count, pattern);
+ buf = p = qemu_io_alloc(blk, count, pattern, register_buf);
for (i = 0; i < nr_iov; i++) {
qemu_iovec_add(qiov, p, sizes[i]);
@@ -539,7 +543,7 @@
}
static int do_pread(BlockBackend *blk, char *buf, int64_t offset,
- int64_t bytes, int64_t *total)
+ int64_t bytes, BdrvRequestFlags flags, int64_t *total)
{
int ret;
@@ -547,7 +551,7 @@
return -ERANGE;
}
- ret = blk_pread(blk, offset, bytes, (uint8_t *)buf, 0);
+ ret = blk_pread(blk, offset, bytes, (uint8_t *)buf, flags);
if (ret < 0) {
return ret;
}
@@ -638,11 +642,11 @@
}
static int do_aio_readv(BlockBackend *blk, QEMUIOVector *qiov,
- int64_t offset, int *total)
+ int64_t offset, BdrvRequestFlags flags, int *total)
{
int async_ret = NOT_DONE;
- blk_aio_preadv(blk, offset, qiov, 0, aio_rw_done, &async_ret);
+ blk_aio_preadv(blk, offset, qiov, flags, aio_rw_done, &async_ret);
while (async_ret == NOT_DONE) {
main_loop_wait(false);
}
@@ -682,6 +686,7 @@
" -p, -- ignored for backwards compatibility\n"
" -P, -- use a pattern to verify read data\n"
" -q, -- quiet mode, do not show I/O statistics\n"
+" -r, -- register I/O buffer\n"
" -s, -- start offset for pattern verification (only with -P)\n"
" -v, -- dump buffer to standard output\n"
"\n");
@@ -695,7 +700,7 @@
.cfunc = read_f,
.argmin = 2,
.argmax = -1,
- .args = "[-abCqv] [-P pattern [-s off] [-l len]] off len",
+ .args = "[-abCqrv] [-P pattern [-s off] [-l len]] off len",
.oneline = "reads a number of bytes at a specified offset",
.help = read_help,
};
@@ -713,8 +718,9 @@
int64_t total = 0;
int pattern = 0;
int64_t pattern_offset = 0, pattern_count = 0;
+ BdrvRequestFlags flags = 0;
- while ((c = getopt(argc, argv, "bCl:pP:qs:v")) != -1) {
+ while ((c = getopt(argc, argv, "bCl:pP:qrs:v")) != -1) {
switch (c) {
case 'b':
bflag = true;
@@ -743,6 +749,9 @@
case 'q':
qflag = true;
break;
+ case 'r':
+ flags |= BDRV_REQ_REGISTERED_BUF;
+ break;
case 's':
sflag = true;
pattern_offset = cvtnum(optarg);
@@ -807,15 +816,20 @@
count);
return -EINVAL;
}
+ if (flags & BDRV_REQ_REGISTERED_BUF) {
+ printf("I/O buffer registration is not supported when reading "
+ "from vmstate\n");
+ return -EINVAL;
+ }
}
- buf = qemu_io_alloc(blk, count, 0xab);
+ buf = qemu_io_alloc(blk, count, 0xab, flags & BDRV_REQ_REGISTERED_BUF);
clock_gettime(CLOCK_MONOTONIC, &t1);
if (bflag) {
ret = do_load_vmstate(blk, buf, offset, count, &total);
} else {
- ret = do_pread(blk, buf, offset, count, &total);
+ ret = do_pread(blk, buf, offset, count, flags, &total);
}
clock_gettime(CLOCK_MONOTONIC, &t2);
@@ -852,7 +866,7 @@
print_report("read", &t2, offset, count, total, cnt, Cflag);
out:
- qemu_io_free(buf);
+ qemu_io_free(blk, buf, count, flags & BDRV_REQ_REGISTERED_BUF);
return ret;
}
@@ -870,8 +884,9 @@
" Uses multiple iovec buffers if more than one byte range is specified.\n"
" -C, -- report statistics in a machine parsable format\n"
" -P, -- use a pattern to verify read data\n"
-" -v, -- dump buffer to standard output\n"
" -q, -- quiet mode, do not show I/O statistics\n"
+" -r, -- register I/O buffer\n"
+" -v, -- dump buffer to standard output\n"
"\n");
}
@@ -882,7 +897,7 @@
.cfunc = readv_f,
.argmin = 2,
.argmax = -1,
- .args = "[-Cqv] [-P pattern] off len [len..]",
+ .args = "[-Cqrv] [-P pattern] off len [len..]",
.oneline = "reads a number of bytes at a specified offset",
.help = readv_help,
};
@@ -900,8 +915,9 @@
QEMUIOVector qiov;
int pattern = 0;
bool Pflag = false;
+ BdrvRequestFlags flags = 0;
- while ((c = getopt(argc, argv, "CP:qv")) != -1) {
+ while ((c = getopt(argc, argv, "CP:qrv")) != -1) {
switch (c) {
case 'C':
Cflag = true;
@@ -916,6 +932,9 @@
case 'q':
qflag = true;
break;
+ case 'r':
+ flags |= BDRV_REQ_REGISTERED_BUF;
+ break;
case 'v':
vflag = true;
break;
@@ -939,13 +958,14 @@
optind++;
nr_iov = argc - optind;
- buf = create_iovec(blk, &qiov, &argv[optind], nr_iov, 0xab);
+ buf = create_iovec(blk, &qiov, &argv[optind], nr_iov, 0xab,
+ flags & BDRV_REQ_REGISTERED_BUF);
if (buf == NULL) {
return -EINVAL;
}
clock_gettime(CLOCK_MONOTONIC, &t1);
- ret = do_aio_readv(blk, &qiov, offset, &total);
+ ret = do_aio_readv(blk, &qiov, offset, flags, &total);
clock_gettime(CLOCK_MONOTONIC, &t2);
if (ret < 0) {
@@ -980,8 +1000,8 @@
print_report("read", &t2, offset, qiov.size, total, cnt, Cflag);
out:
+ qemu_io_free(blk, buf, qiov.size, flags & BDRV_REQ_REGISTERED_BUF);
qemu_iovec_destroy(&qiov);
- qemu_io_free(buf);
return ret;
}
@@ -998,13 +1018,14 @@
" filled with a set pattern (0xcdcdcdcd).\n"
" -b, -- write to the VM state rather than the virtual disk\n"
" -c, -- write compressed data with blk_write_compressed\n"
+" -C, -- report statistics in a machine parsable format\n"
" -f, -- use Force Unit Access semantics\n"
" -n, -- with -z, don't allow slow fallback\n"
" -p, -- ignored for backwards compatibility\n"
" -P, -- use different pattern to fill file\n"
-" -s, -- use a pattern file to fill the write buffer\n"
-" -C, -- report statistics in a machine parsable format\n"
" -q, -- quiet mode, do not show I/O statistics\n"
+" -r, -- register I/O buffer\n"
+" -s, -- use a pattern file to fill the write buffer\n"
" -u, -- with -z, allow unmapping\n"
" -z, -- write zeroes using blk_pwrite_zeroes\n"
"\n");
@@ -1019,7 +1040,7 @@
.perm = BLK_PERM_WRITE,
.argmin = 2,
.argmax = -1,
- .args = "[-bcCfnquz] [-P pattern | -s source_file] off len",
+ .args = "[-bcCfnqruz] [-P pattern | -s source_file] off len",
.oneline = "writes a number of bytes at a specified offset",
.help = write_help,
};
@@ -1039,7 +1060,7 @@
int pattern = 0xcd;
const char *file_name = NULL;
- while ((c = getopt(argc, argv, "bcCfnpP:qs:uz")) != -1) {
+ while ((c = getopt(argc, argv, "bcCfnpP:qrs:uz")) != -1) {
switch (c) {
case 'b':
bflag = true;
@@ -1069,6 +1090,9 @@
case 'q':
qflag = true;
break;
+ case 'r':
+ flags |= BDRV_REQ_REGISTERED_BUF;
+ break;
case 's':
sflag = true;
file_name = optarg;
@@ -1148,14 +1172,21 @@
}
}
- if (!zflag) {
+ if (zflag) {
+ if (flags & BDRV_REQ_REGISTERED_BUF) {
+ printf("cannot combine zero write with registered I/O buffer\n");
+ return -EINVAL;
+ }
+ } else {
if (sflag) {
- buf = qemu_io_alloc_from_file(blk, count, file_name);
+ buf = qemu_io_alloc_from_file(blk, count, file_name,
+ flags & BDRV_REQ_REGISTERED_BUF);
if (!buf) {
return -EINVAL;
}
} else {
- buf = qemu_io_alloc(blk, count, pattern);
+ buf = qemu_io_alloc(blk, count, pattern,
+ flags & BDRV_REQ_REGISTERED_BUF);
}
}
@@ -1189,7 +1220,7 @@
out:
if (!zflag) {
- qemu_io_free(buf);
+ qemu_io_free(blk, buf, count, flags & BDRV_REQ_REGISTERED_BUF);
}
return ret;
}
@@ -1206,10 +1237,11 @@
"\n"
" Writes into a segment of the currently open file, using a buffer\n"
" filled with a set pattern (0xcdcdcdcd).\n"
-" -P, -- use different pattern to fill file\n"
" -C, -- report statistics in a machine parsable format\n"
" -f, -- use Force Unit Access semantics\n"
+" -P, -- use different pattern to fill file\n"
" -q, -- quiet mode, do not show I/O statistics\n"
+" -r, -- register I/O buffer\n"
"\n");
}
@@ -1221,7 +1253,7 @@
.perm = BLK_PERM_WRITE,
.argmin = 2,
.argmax = -1,
- .args = "[-Cfq] [-P pattern] off len [len..]",
+ .args = "[-Cfqr] [-P pattern] off len [len..]",
.oneline = "writes a number of bytes at a specified offset",
.help = writev_help,
};
@@ -1240,7 +1272,7 @@
int pattern = 0xcd;
QEMUIOVector qiov;
- while ((c = getopt(argc, argv, "CfqP:")) != -1) {
+ while ((c = getopt(argc, argv, "CfP:qr")) != -1) {
switch (c) {
case 'C':
Cflag = true;
@@ -1251,6 +1283,9 @@
case 'q':
qflag = true;
break;
+ case 'r':
+ flags |= BDRV_REQ_REGISTERED_BUF;
+ break;
case 'P':
pattern = parse_pattern(optarg);
if (pattern < 0) {
@@ -1276,7 +1311,8 @@
optind++;
nr_iov = argc - optind;
- buf = create_iovec(blk, &qiov, &argv[optind], nr_iov, pattern);
+ buf = create_iovec(blk, &qiov, &argv[optind], nr_iov, pattern,
+ flags & BDRV_REQ_REGISTERED_BUF);
if (buf == NULL) {
return -EINVAL;
}
@@ -1301,8 +1337,8 @@
t2 = tsub(t2, t1);
print_report("wrote", &t2, offset, qiov.size, total, cnt, Cflag);
out:
+ qemu_io_free(blk, buf, qiov.size, flags & BDRV_REQ_REGISTERED_BUF);
qemu_iovec_destroy(&qiov);
- qemu_io_free(buf);
return ret;
}
@@ -1318,6 +1354,7 @@
bool zflag;
BlockAcctCookie acct;
int pattern;
+ BdrvRequestFlags flags;
struct timespec t1;
};
@@ -1347,7 +1384,8 @@
ctx->qiov.size, 1, ctx->Cflag);
out:
if (!ctx->zflag) {
- qemu_io_free(ctx->buf);
+ qemu_io_free(ctx->blk, ctx->buf, ctx->qiov.size,
+ ctx->flags & BDRV_REQ_REGISTERED_BUF);
qemu_iovec_destroy(&ctx->qiov);
}
g_free(ctx);
@@ -1392,7 +1430,8 @@
print_report("read", &t2, ctx->offset, ctx->qiov.size,
ctx->qiov.size, 1, ctx->Cflag);
out:
- qemu_io_free(ctx->buf);
+ qemu_io_free(ctx->blk, ctx->buf, ctx->qiov.size,
+ ctx->flags & BDRV_REQ_REGISTERED_BUF);
qemu_iovec_destroy(&ctx->qiov);
g_free(ctx);
}
@@ -1414,10 +1453,11 @@
" considered successful once the request is submitted, independently\n"
" of potential I/O errors or pattern mismatches.\n"
" -C, -- report statistics in a machine parsable format\n"
-" -P, -- use a pattern to verify read data\n"
" -i, -- treat request as invalid, for exercising stats\n"
-" -v, -- dump buffer to standard output\n"
+" -P, -- use a pattern to verify read data\n"
" -q, -- quiet mode, do not show I/O statistics\n"
+" -r, -- register I/O buffer\n"
+" -v, -- dump buffer to standard output\n"
"\n");
}
@@ -1428,7 +1468,7 @@
.cfunc = aio_read_f,
.argmin = 2,
.argmax = -1,
- .args = "[-Ciqv] [-P pattern] off len [len..]",
+ .args = "[-Ciqrv] [-P pattern] off len [len..]",
.oneline = "asynchronously reads a number of bytes",
.help = aio_read_help,
};
@@ -1439,7 +1479,7 @@
struct aio_ctx *ctx = g_new0(struct aio_ctx, 1);
ctx->blk = blk;
- while ((c = getopt(argc, argv, "CP:iqv")) != -1) {
+ while ((c = getopt(argc, argv, "CiP:qrv")) != -1) {
switch (c) {
case 'C':
ctx->Cflag = true;
@@ -1460,6 +1500,9 @@
case 'q':
ctx->qflag = true;
break;
+ case 'r':
+ ctx->flags |= BDRV_REQ_REGISTERED_BUF;
+ break;
case 'v':
ctx->vflag = true;
break;
@@ -1486,7 +1529,8 @@
optind++;
nr_iov = argc - optind;
- ctx->buf = create_iovec(blk, &ctx->qiov, &argv[optind], nr_iov, 0xab);
+ ctx->buf = create_iovec(blk, &ctx->qiov, &argv[optind], nr_iov, 0xab,
+ ctx->flags & BDRV_REQ_REGISTERED_BUF);
if (ctx->buf == NULL) {
block_acct_invalid(blk_get_stats(blk), BLOCK_ACCT_READ);
g_free(ctx);
@@ -1496,7 +1540,8 @@
clock_gettime(CLOCK_MONOTONIC, &ctx->t1);
block_acct_start(blk_get_stats(blk), &ctx->acct, ctx->qiov.size,
BLOCK_ACCT_READ);
- blk_aio_preadv(blk, ctx->offset, &ctx->qiov, 0, aio_read_done, ctx);
+ blk_aio_preadv(blk, ctx->offset, &ctx->qiov, ctx->flags, aio_read_done,
+ ctx);
return 0;
}
@@ -1517,11 +1562,12 @@
" Note that due to its asynchronous nature, this command will be\n"
" considered successful once the request is submitted, independently\n"
" of potential I/O errors or pattern mismatches.\n"
-" -P, -- use different pattern to fill file\n"
" -C, -- report statistics in a machine parsable format\n"
" -f, -- use Force Unit Access semantics\n"
" -i, -- treat request as invalid, for exercising stats\n"
+" -P, -- use different pattern to fill file\n"
" -q, -- quiet mode, do not show I/O statistics\n"
+" -r, -- register I/O buffer\n"
" -u, -- with -z, allow unmapping\n"
" -z, -- write zeroes using blk_aio_pwrite_zeroes\n"
"\n");
@@ -1535,7 +1581,7 @@
.perm = BLK_PERM_WRITE,
.argmin = 2,
.argmax = -1,
- .args = "[-Cfiquz] [-P pattern] off len [len..]",
+ .args = "[-Cfiqruz] [-P pattern] off len [len..]",
.oneline = "asynchronously writes a number of bytes",
.help = aio_write_help,
};
@@ -1545,22 +1591,24 @@
int nr_iov, c;
int pattern = 0xcd;
struct aio_ctx *ctx = g_new0(struct aio_ctx, 1);
- BdrvRequestFlags flags = 0;
ctx->blk = blk;
- while ((c = getopt(argc, argv, "CfiqP:uz")) != -1) {
+ while ((c = getopt(argc, argv, "CfiP:qruz")) != -1) {
switch (c) {
case 'C':
ctx->Cflag = true;
break;
case 'f':
- flags |= BDRV_REQ_FUA;
+ ctx->flags |= BDRV_REQ_FUA;
break;
case 'q':
ctx->qflag = true;
break;
+ case 'r':
+ ctx->flags |= BDRV_REQ_REGISTERED_BUF;
+ break;
case 'u':
- flags |= BDRV_REQ_MAY_UNMAP;
+ ctx->flags |= BDRV_REQ_MAY_UNMAP;
break;
case 'P':
pattern = parse_pattern(optarg);
@@ -1596,7 +1644,7 @@
return -EINVAL;
}
- if ((flags & BDRV_REQ_MAY_UNMAP) && !ctx->zflag) {
+ if ((ctx->flags & BDRV_REQ_MAY_UNMAP) && !ctx->zflag) {
printf("-u requires -z to be specified\n");
g_free(ctx);
return -EINVAL;
@@ -1608,6 +1656,12 @@
return -EINVAL;
}
+ if (ctx->zflag && (ctx->flags & BDRV_REQ_REGISTERED_BUF)) {
+ printf("cannot combine zero write with registered I/O buffer\n");
+ g_free(ctx);
+ return -EINVAL;
+ }
+
ctx->offset = cvtnum(argv[optind]);
if (ctx->offset < 0) {
int ret = ctx->offset;
@@ -1626,12 +1680,12 @@
}
ctx->qiov.size = count;
- blk_aio_pwrite_zeroes(blk, ctx->offset, count, flags, aio_write_done,
- ctx);
+ blk_aio_pwrite_zeroes(blk, ctx->offset, count, ctx->flags,
+ aio_write_done, ctx);
} else {
nr_iov = argc - optind;
ctx->buf = create_iovec(blk, &ctx->qiov, &argv[optind], nr_iov,
- pattern);
+ pattern, ctx->flags & BDRV_REQ_REGISTERED_BUF);
if (ctx->buf == NULL) {
block_acct_invalid(blk_get_stats(blk), BLOCK_ACCT_WRITE);
g_free(ctx);
@@ -1642,8 +1696,8 @@
block_acct_start(blk_get_stats(blk), &ctx->acct, ctx->qiov.size,
BLOCK_ACCT_WRITE);
- blk_aio_pwritev(blk, ctx->offset, &ctx->qiov, flags, aio_write_done,
- ctx);
+ blk_aio_pwritev(blk, ctx->offset, &ctx->qiov, ctx->flags,
+ aio_write_done, ctx);
}
return 0;
