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virtio-9p: Add sg helper functions 

Add scatter-gather helper functions.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This commit is contained in:
Anthony Liguori 2010-04-29 17:44:50 +05:30
parent bb9e3216bf
commit 1f5a89bf68
1 changed files with 53 additions and 0 deletions
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53
hw/virtio-9p.c
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@ -762,6 +762,56 @@ static int stat_to_v9stat(V9fsState *s, V9fsString *name,
return 0;
}
static struct iovec *adjust_sg(struct iovec *sg, int len, int *iovcnt)
{
while (len && *iovcnt) {
if (len < sg->iov_len) {
sg->iov_len -= len;
sg->iov_base += len;
len = 0;
} else {
len -= sg->iov_len;
sg++;
*iovcnt -= 1;
}
}
return sg;
}
static struct iovec *cap_sg(struct iovec *sg, int cap, int *cnt)
{
int i;
int total = 0;
for (i = 0; i < *cnt; i++) {
if ((total + sg[i].iov_len) > cap) {
sg[i].iov_len -= ((total + sg[i].iov_len) - cap);
i++;
break;
}
total += sg[i].iov_len;
}
*cnt = i;
return sg;
}
static void print_sg(struct iovec *sg, int cnt)
{
int i;
printf("sg[%d]: {", cnt);
for (i = 0; i < cnt; i++) {
if (i) {
printf(", ");
}
printf("(%p, %zd)", sg[i].iov_base, sg[i].iov_len);
}
printf("}\n");
}
static void v9fs_dummy(V9fsState *s, V9fsPDU *pdu)
{
/* Note: The following have been added to prevent GCC from complaining
@ -786,6 +836,9 @@ static void v9fs_dummy(V9fsState *s, V9fsPDU *pdu)
(void) donttouch_stat;
(void) v9fs_stat_free;
(void) stat_to_v9stat;
(void) adjust_sg;
(void) cap_sg;
(void) print_sg;
}
static void v9fs_version(V9fsState *s, V9fsPDU *pdu)