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block: Skip COR for inactive nodes

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We must not write data to inactive nodes, and a COR is certainly
something we can simply not do without upsetting anyone.  So skip COR
operations on inactive nodes.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20191001174827.11081-2-mreitz@redhat.com
Message-Id: <20191001174827.11081-2-mreitz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Max Reitz 2019-10-01 19:48:26 +02:00 committed by Stefan Hajnoczi
parent 9b92fbcf45
commit 8644476e51
1 changed files with 27 additions and 14 deletions
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15
block/io.c
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@ -1246,11 +1246,18 @@ static int coroutine_fn bdrv_co_do_copy_on_readv(BdrvChild *child,
int max_transfer = MIN_NON_ZERO(bs->bl.max_transfer, int max_transfer = MIN_NON_ZERO(bs->bl.max_transfer,
BDRV_REQUEST_MAX_BYTES); BDRV_REQUEST_MAX_BYTES);
unsigned int progress = 0; unsigned int progress = 0;
bool skip_write;
if (!drv) { if (!drv) {
return -ENOMEDIUM; return -ENOMEDIUM;
} }
/*
* Do not write anything when the BDS is inactive. That is not
* allowed, and it would not help.
*/
skip_write = (bs->open_flags & BDRV_O_INACTIVE);
/* FIXME We cannot require callers to have write permissions when all they /* FIXME We cannot require callers to have write permissions when all they
* are doing is a read request. If we did things right, write permissions * are doing is a read request. If we did things right, write permissions
* would be obtained anyway, but internally by the copy-on-read code. As * would be obtained anyway, but internally by the copy-on-read code. As
@ -1274,10 +1281,15 @@ static int coroutine_fn bdrv_co_do_copy_on_readv(BdrvChild *child,
while (cluster_bytes) { while (cluster_bytes) {
int64_t pnum; int64_t pnum;
if (skip_write) {
ret = 1; /* "already allocated", so nothing will be copied */
pnum = MIN(cluster_bytes, max_transfer);
} else {
ret = bdrv_is_allocated(bs, cluster_offset, ret = bdrv_is_allocated(bs, cluster_offset,
MIN(cluster_bytes, max_transfer), &pnum); MIN(cluster_bytes, max_transfer), &pnum);
if (ret < 0) { if (ret < 0) {
/* Safe to treat errors in querying allocation as if /*
* Safe to treat errors in querying allocation as if
* unallocated; we'll probably fail again soon on the * unallocated; we'll probably fail again soon on the
* read, but at least that will set a decent errno. * read, but at least that will set a decent errno.
*/ */
@ -1291,6 +1303,7 @@ static int coroutine_fn bdrv_co_do_copy_on_readv(BdrvChild *child,
} }
assert(skip_bytes < pnum); assert(skip_bytes < pnum);
}
if (ret <= 0) { if (ret <= 0) {
QEMUIOVector local_qiov; QEMUIOVector local_qiov;