diff options
author | BenoƮt Canet <benoit@irqsave.net> | 2014-02-21 22:21:13 +0100 |
---|---|---|
committer | Kevin Wolf <kwolf@redhat.com> | 2014-02-21 22:29:49 +0100 |
commit | f70d7f7e4d05b7a7797815afdcb83f4375740838 (patch) | |
tree | 6669fa46bb6c9b145846739ba3408a2b68905d41 /util/iov.c | |
parent | 13e7956e3190b51f02e75374bb9dfdcacfd08829 (diff) |
blkverify: Extract qemu_iovec_clone() and qemu_iovec_compare() from blkverify.
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>
Diffstat (limited to 'util/iov.c')
-rw-r--r-- | util/iov.c | 106 |
1 files changed, 106 insertions, 0 deletions
diff --git a/util/iov.c b/util/iov.c index bb46c04e4d..03934da74d 100644 --- a/util/iov.c +++ b/util/iov.c @@ -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) { |