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authorVladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>2020-12-11 21:39:22 +0300
committerEric Blake <eblake@redhat.com>2021-02-03 08:00:52 -0600
commitf0deecff827c838a71f83539b0572094aefe3d5e (patch)
tree698506b20ec742efd6fea0cac097997aa575137d /block
parenta56ed80c429610aecd6f74fbd4a9467f5466278a (diff)
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block/io: refactor bdrv_pad_request(): move bdrv_pad_request() up
Prepare for the following patch when bdrv_pad_request() will be able to fail. Update the comments. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20201211183934.169161-5-vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> [eblake: grammar tweak] Signed-off-by: Eric Blake <eblake@redhat.com>
Diffstat (limited to 'block')
-rw-r--r--block/io.c25
1 files changed, 19 insertions, 6 deletions
diff --git a/block/io.c b/block/io.c
index c8c9dea..3b1aec3 100644
--- a/block/io.c
+++ b/block/io.c
@@ -2135,6 +2135,7 @@ int coroutine_fn bdrv_co_pwritev_part(BdrvChild *child,
uint64_t align = bs->bl.request_alignment;
BdrvRequestPadding pad;
int ret;
+ bool padded = false;
trace_bdrv_co_pwritev(child->bs, offset, bytes, flags);
@@ -2166,20 +2167,32 @@ int coroutine_fn bdrv_co_pwritev_part(BdrvChild *child,
return 0;
}
+ if (!(flags & BDRV_REQ_ZERO_WRITE)) {
+ /*
+ * Pad request for following read-modify-write cycle.
+ * bdrv_co_do_zero_pwritev() does aligning by itself, so, we do
+ * alignment only if there is no ZERO flag.
+ */
+ padded = bdrv_pad_request(bs, &qiov, &qiov_offset, &offset, &bytes,
+ &pad);
+ }
+
bdrv_inc_in_flight(bs);
- /*
- * Align write if necessary by performing a read-modify-write cycle.
- * Pad qiov with the read parts and be sure to have a tracked request not
- * only for bdrv_aligned_pwritev, but also for the reads of the RMW cycle.
- */
tracked_request_begin(&req, bs, offset, bytes, BDRV_TRACKED_WRITE);
if (flags & BDRV_REQ_ZERO_WRITE) {
+ assert(!padded);
ret = bdrv_co_do_zero_pwritev(child, offset, bytes, flags, &req);
goto out;
}
- if (bdrv_pad_request(bs, &qiov, &qiov_offset, &offset, &bytes, &pad)) {
+ if (padded) {
+ /*
+ * Request was unaligned to request_alignment and therefore
+ * padded. We are going to do read-modify-write, and must
+ * serialize the request to prevent interactions of the
+ * widened region with other transactions.
+ */
bdrv_make_request_serialising(&req, align);
bdrv_padding_rmw_read(child, &req, &pad, false);
}