qemu-nbd has a limit of slightly less than 1M per request. Work
around this in the nbd block driver.
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
block/nbd.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++------
1 files changed, 46 insertions(+), 6 deletions(-)
diff --git a/block/nbd.c b/block/nbd.c
index 90c4f2f..a52b6f2 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -277,8 +277,9 @@ static int nbd_open(BlockDriverState *bs, const char*
filename, int flags)
return result;
}
-static int nbd_co_readv(BlockDriverState *bs, int64_t sector_num,
- int nb_sectors, QEMUIOVector *qiov)
+static int nbd_co_readv_1(BlockDriverState *bs, int64_t sector_num,
+ int nb_sectors, QEMUIOVector *qiov,
+ int offset)
{
BDRVNBDState *s = bs->opaque;
struct nbd_request request;
@@ -292,15 +293,16 @@ static int nbd_co_readv(BlockDriverState *bs, int64_t
sector_num,
if (nbd_co_send_request(s, &request, NULL, 0) == -1) {
reply.error = errno;
} else {
- nbd_co_receive_reply(s, &request, &reply, qiov->iov, 0);
+ nbd_co_receive_reply(s, &request, &reply, qiov->iov, offset);
}
nbd_coroutine_end(s, &request);
return -reply.error;
}
-static int nbd_co_writev(BlockDriverState *bs, int64_t sector_num,
- int nb_sectors, QEMUIOVector *qiov)
+static int nbd_co_writev_1(BlockDriverState *bs, int64_t sector_num,
+ int nb_sectors, QEMUIOVector *qiov,
+ int offset)
{
BDRVNBDState *s = bs->opaque;
struct nbd_request request;
@@ -315,7 +317,7 @@ static int nbd_co_writev(BlockDriverState *bs, int64_t
sector_num,
request.len = nb_sectors * 512;
nbd_coroutine_start(s, &request);
- if (nbd_co_send_request(s, &request, qiov->iov, 0) == -1) {
+ if (nbd_co_send_request(s, &request, qiov->iov, offset) == -1) {
reply.error = errno;
} else {
nbd_co_receive_reply(s, &request, &reply, NULL, 0);
@@ -324,6 +326,44 @@ static int nbd_co_writev(BlockDriverState *bs, int64_t
sector_num,
return -reply.error;
}
+/* qemu-nbd has a limit of slightly less than 1M per request. Try to
+ * remain aligned to 4K. */
+#define NBD_MAX_SECTORS 2040
+
+static int nbd_co_readv(BlockDriverState *bs, int64_t sector_num,
+ int nb_sectors, QEMUIOVector *qiov)
+{
+ int offset = 0;
+ int ret;
+ while (nb_sectors > NBD_MAX_SECTORS) {
+ ret = nbd_co_readv_1(bs, sector_num, NBD_MAX_SECTORS, qiov, offset);
+ if (ret < 0) {
+ return ret;
+ }
+ offset += NBD_MAX_SECTORS * 512;
+ sector_num += NBD_MAX_SECTORS;
+ nb_sectors -= NBD_MAX_SECTORS;
+ }
+ return nbd_co_readv_1(bs, sector_num, nb_sectors, qiov, offset);
+}
+
+static int nbd_co_writev(BlockDriverState *bs, int64_t sector_num,
+ int nb_sectors, QEMUIOVector *qiov)
+{
+ int offset = 0;
+ int ret;
+ while (nb_sectors > NBD_MAX_SECTORS) {
+ ret = nbd_co_writev_1(bs, sector_num, NBD_MAX_SECTORS, qiov, offset);
+ if (ret < 0) {
+ return ret;
+ }
+ offset += NBD_MAX_SECTORS * 512;
+ sector_num += NBD_MAX_SECTORS;
+ nb_sectors -= NBD_MAX_SECTORS;
+ }
+ return nbd_co_writev_1(bs, sector_num, nb_sectors, qiov, offset);
+}
+
static int nbd_co_flush(BlockDriverState *bs)
{
BDRVNBDState *s = bs->opaque;
--
1.7.6
