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blkverify: Extract qemu_iovec_clone() and qemu_iovec_compare() from b…
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…lkverify.

qemu_iovec_compare() will be used to compare IOs vectors in quorum blkverify
mode. The patch extracts these functions in order to factorize the code.

Signed-off-by: Benoit Canet <benoit@irqsave.net>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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@benoit-canet @kevmw
benoit-canet authored and kevmw committed Feb 21, 2014
1 parent 13e7956 commit f70d7f7
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Showing 3 changed files with 110 additions and 106 deletions.
108 changes: 2 additions & 106 deletions block/blkverify.c
View file
Expand Up @@ -173,110 +173,6 @@ static int64_t blkverify_getlength(BlockDriverState *bs)
return bdrv_getlength(s->test_file);
}

/**
* Check that I/O vector contents are identical
*
* @a: I/O vector
* @b: I/O vector
* @ret: Offset to first mismatching byte or -1 if match
*/
static ssize_t blkverify_iovec_compare(QEMUIOVector *a, QEMUIOVector *b)
{
int i;
ssize_t offset = 0;

assert(a->niov == b->niov);
for (i = 0; i < a->niov; i++) {
size_t len = 0;
uint8_t *p = (uint8_t *)a->iov[i].iov_base;
uint8_t *q = (uint8_t *)b->iov[i].iov_base;

assert(a->iov[i].iov_len == b->iov[i].iov_len);
while (len < a->iov[i].iov_len && *p++ == *q++) {
len++;
}

offset += len;

if (len != a->iov[i].iov_len) {
return offset;
}
}
return -1;
}

typedef struct {
int src_index;
struct iovec *src_iov;
void *dest_base;
} IOVectorSortElem;

static int sortelem_cmp_src_base(const void *a, const void *b)
{
const IOVectorSortElem *elem_a = a;
const IOVectorSortElem *elem_b = b;

/* Don't overflow */
if (elem_a->src_iov->iov_base < elem_b->src_iov->iov_base) {
return -1;
} else if (elem_a->src_iov->iov_base > elem_b->src_iov->iov_base) {
return 1;
} else {
return 0;
}
}

static int sortelem_cmp_src_index(const void *a, const void *b)
{
const IOVectorSortElem *elem_a = a;
const IOVectorSortElem *elem_b = b;

return elem_a->src_index - elem_b->src_index;
}

/**
* Copy contents of I/O vector
*
* The relative relationships of overlapping iovecs are preserved. This is
* necessary to ensure identical semantics in the cloned I/O vector.
*/
static void blkverify_iovec_clone(QEMUIOVector *dest, const QEMUIOVector *src,
void *buf)
{
IOVectorSortElem sortelems[src->niov];
void *last_end;
int i;

/* Sort by source iovecs by base address */
for (i = 0; i < src->niov; i++) {
sortelems[i].src_index = i;
sortelems[i].src_iov = &src->iov[i];
}
qsort(sortelems, src->niov, sizeof(sortelems[0]), sortelem_cmp_src_base);

/* Allocate buffer space taking into account overlapping iovecs */
last_end = NULL;
for (i = 0; i < src->niov; i++) {
struct iovec *cur = sortelems[i].src_iov;
ptrdiff_t rewind = 0;

/* Detect overlap */
if (last_end && last_end > cur->iov_base) {
rewind = last_end - cur->iov_base;
}

sortelems[i].dest_base = buf - rewind;
buf += cur->iov_len - MIN(rewind, cur->iov_len);
last_end = MAX(cur->iov_base + cur->iov_len, last_end);
}

/* Sort by source iovec index and build destination iovec */
qsort(sortelems, src->niov, sizeof(sortelems[0]), sortelem_cmp_src_index);
for (i = 0; i < src->niov; i++) {
qemu_iovec_add(dest, sortelems[i].dest_base, src->iov[i].iov_len);
}
}

static BlkverifyAIOCB *blkverify_aio_get(BlockDriverState *bs, bool is_write,
int64_t sector_num, QEMUIOVector *qiov,
int nb_sectors,
Expand Down Expand Up @@ -340,7 +236,7 @@ static void blkverify_aio_cb(void *opaque, int ret)

static void blkverify_verify_readv(BlkverifyAIOCB *acb)
{
ssize_t offset = blkverify_iovec_compare(acb->qiov, &acb->raw_qiov);
ssize_t offset = qemu_iovec_compare(acb->qiov, &acb->raw_qiov);
if (offset != -1) {
blkverify_err(acb, "contents mismatch in sector %" PRId64,
acb->sector_num + (int64_t)(offset / BDRV_SECTOR_SIZE));
Expand All @@ -358,7 +254,7 @@ static BlockDriverAIOCB *blkverify_aio_readv(BlockDriverState *bs,
acb->verify = blkverify_verify_readv;
acb->buf = qemu_blockalign(bs->file, qiov->size);
qemu_iovec_init(&acb->raw_qiov, acb->qiov->niov);
blkverify_iovec_clone(&acb->raw_qiov, qiov, acb->buf);
qemu_iovec_clone(&acb->raw_qiov, qiov, acb->buf);

bdrv_aio_readv(s->test_file, sector_num, qiov, nb_sectors,
blkverify_aio_cb, acb);
Expand Down
2 changes: 2 additions & 0 deletions include/qemu-common.h
View file
Expand Up @@ -338,6 +338,8 @@ size_t qemu_iovec_from_buf(QEMUIOVector *qiov, size_t offset,
const void *buf, size_t bytes);
size_t qemu_iovec_memset(QEMUIOVector *qiov, size_t offset,
int fillc, size_t bytes);
ssize_t qemu_iovec_compare(QEMUIOVector *a, QEMUIOVector *b);
void qemu_iovec_clone(QEMUIOVector *dest, const QEMUIOVector *src, void *buf);

bool buffer_is_zero(const void *buf, size_t len);

Expand Down
106 changes: 106 additions & 0 deletions util/iov.c
View file
Expand Up @@ -378,6 +378,112 @@ size_t qemu_iovec_memset(QEMUIOVector *qiov, size_t offset,
return iov_memset(qiov->iov, qiov->niov, offset, fillc, bytes);
}

/**
* Check that I/O vector contents are identical
*
* The IO vectors must have the same structure (same length of all parts).
* A typical usage is to compare vectors created with qemu_iovec_clone().
*
* @a: I/O vector
* @b: I/O vector
* @ret: Offset to first mismatching byte or -1 if match
*/
ssize_t qemu_iovec_compare(QEMUIOVector *a, QEMUIOVector *b)
{
int i;
ssize_t offset = 0;

assert(a->niov == b->niov);
for (i = 0; i < a->niov; i++) {
size_t len = 0;
uint8_t *p = (uint8_t *)a->iov[i].iov_base;
uint8_t *q = (uint8_t *)b->iov[i].iov_base;

assert(a->iov[i].iov_len == b->iov[i].iov_len);
while (len < a->iov[i].iov_len && *p++ == *q++) {
len++;
}

offset += len;

if (len != a->iov[i].iov_len) {
return offset;
}
}
return -1;
}

typedef struct {
int src_index;
struct iovec *src_iov;
void *dest_base;
} IOVectorSortElem;

static int sortelem_cmp_src_base(const void *a, const void *b)
{
const IOVectorSortElem *elem_a = a;
const IOVectorSortElem *elem_b = b;

/* Don't overflow */
if (elem_a->src_iov->iov_base < elem_b->src_iov->iov_base) {
return -1;
} else if (elem_a->src_iov->iov_base > elem_b->src_iov->iov_base) {
return 1;
} else {
return 0;
}
}

static int sortelem_cmp_src_index(const void *a, const void *b)
{
const IOVectorSortElem *elem_a = a;
const IOVectorSortElem *elem_b = b;

return elem_a->src_index - elem_b->src_index;
}

/**
* Copy contents of I/O vector
*
* The relative relationships of overlapping iovecs are preserved. This is
* necessary to ensure identical semantics in the cloned I/O vector.
*/
void qemu_iovec_clone(QEMUIOVector *dest, const QEMUIOVector *src, void *buf)
{
IOVectorSortElem sortelems[src->niov];
void *last_end;
int i;

/* Sort by source iovecs by base address */
for (i = 0; i < src->niov; i++) {
sortelems[i].src_index = i;
sortelems[i].src_iov = &src->iov[i];
}
qsort(sortelems, src->niov, sizeof(sortelems[0]), sortelem_cmp_src_base);

/* Allocate buffer space taking into account overlapping iovecs */
last_end = NULL;
for (i = 0; i < src->niov; i++) {
struct iovec *cur = sortelems[i].src_iov;
ptrdiff_t rewind = 0;

/* Detect overlap */
if (last_end && last_end > cur->iov_base) {
rewind = last_end - cur->iov_base;
}

sortelems[i].dest_base = buf - rewind;
buf += cur->iov_len - MIN(rewind, cur->iov_len);
last_end = MAX(cur->iov_base + cur->iov_len, last_end);
}

/* Sort by source iovec index and build destination iovec */
qsort(sortelems, src->niov, sizeof(sortelems[0]), sortelem_cmp_src_index);
for (i = 0; i < src->niov; i++) {
qemu_iovec_add(dest, sortelems[i].dest_base, src->iov[i].iov_len);
}
}

size_t iov_discard_front(struct iovec **iov, unsigned int *iov_cnt,
size_t bytes)
{
Expand Down

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