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qed: Make qed_read_backing_file() synchronous 

Note that this code is generally not running in coroutine context, so
this is an actual blocking synchronous operation. We'll fix this in a
moment.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Kevin Wolf 2016-11-14 14:56:32 +01:00
parent 0f21b7a1b7
commit e85c528142
1 changed files with 18 additions and 14 deletions
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32
block/qed.c
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@ -808,13 +808,13 @@ static BDRVQEDState *acb_to_s(QEDAIOCB *acb)
* This function reads qiov->size bytes starting at pos from the backing file.
* If there is no backing file then zeroes are read.
*/
static void qed_read_backing_file(BDRVQEDState *s, uint64_t pos,
QEMUIOVector *qiov,
QEMUIOVector **backing_qiov,
BlockCompletionFunc *cb, void *opaque)
static int qed_read_backing_file(BDRVQEDState *s, uint64_t pos,
QEMUIOVector *qiov,
QEMUIOVector **backing_qiov)
{
uint64_t backing_length = 0;
size_t size;
int ret;
/* If there is a backing file, get its length. Treat the absence of a
* backing file like a zero length backing file.
@ -822,8 +822,7 @@ static void qed_read_backing_file(BDRVQEDState *s, uint64_t pos,
if (s->bs->backing) {
int64_t l = bdrv_getlength(s->bs->backing->bs);
if (l < 0) {
cb(opaque, l);
return;
return l;
}
backing_length = l;
}
@ -836,8 +835,7 @@ static void qed_read_backing_file(BDRVQEDState *s, uint64_t pos,
/* Complete now if there are no backing file sectors to read */
if (pos >= backing_length) {
cb(opaque, 0);
return;
return 0;
}
/* If the read straddles the end of the backing file, shorten it */
@ -849,8 +847,11 @@ static void qed_read_backing_file(BDRVQEDState *s, uint64_t pos,
qemu_iovec_concat(*backing_qiov, qiov, 0, size);
BLKDBG_EVENT(s->bs->file, BLKDBG_READ_BACKING_AIO);
bdrv_aio_readv(s->bs->backing, pos / BDRV_SECTOR_SIZE,
*backing_qiov, size / BDRV_SECTOR_SIZE, cb, opaque);
ret = bdrv_preadv(s->bs->backing, pos, *backing_qiov);
if (ret < 0) {
return ret;
}
return 0;
}
typedef struct {
@ -907,6 +908,7 @@ static void qed_copy_from_backing_file(BDRVQEDState *s, uint64_t pos,
void *opaque)
{
CopyFromBackingFileCB *copy_cb;
int ret;
/* Skip copy entirely if there is no work to do */
if (len == 0) {
@ -922,8 +924,9 @@ static void qed_copy_from_backing_file(BDRVQEDState *s, uint64_t pos,
copy_cb->iov.iov_len = len;
qemu_iovec_init_external(&copy_cb->qiov, &copy_cb->iov, 1);
qed_read_backing_file(s, pos, &copy_cb->qiov, &copy_cb->backing_qiov,
qed_copy_from_backing_file_write, copy_cb);
ret = qed_read_backing_file(s, pos, &copy_cb->qiov,
&copy_cb->backing_qiov);
qed_copy_from_backing_file_write(copy_cb, ret);
}
/**
@ -1366,8 +1369,9 @@ static void qed_aio_read_data(void *opaque, int ret,
qed_aio_start_io(acb);
return;
} else if (ret != QED_CLUSTER_FOUND) {
qed_read_backing_file(s, acb->cur_pos, &acb->cur_qiov,
&acb->backing_qiov, qed_aio_next_io_cb, acb);
ret = qed_read_backing_file(s, acb->cur_pos, &acb->cur_qiov,
&acb->backing_qiov);
qed_aio_next_io(acb, ret);
return;
}