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[Qemu-devel] [PULL 02/31] qcow2: simplify logic in qcow2_co_write_zeroes
From: |
Kevin Wolf |
Subject: |
[Qemu-devel] [PULL 02/31] qcow2: simplify logic in qcow2_co_write_zeroes |
Date: |
Wed, 8 Jun 2016 11:16:28 +0200 |
From: "Denis V. Lunev" <address@hidden>
Unaligned requests will occupy only one cluster. This is true since the
previous commit. Simplify the code taking this consideration into
account.
In other words, the caller is now buggy if it ever passes us an unaligned
request that crosses cluster boundaries (the only requests that can cross
boundaries will be aligned).
There are no other changes so far.
Signed-off-by: Denis V. Lunev <address@hidden>
Reviewed-by: Eric Blake <address@hidden>
CC: Eric Blake <address@hidden>
CC: Kevin Wolf <address@hidden>
Message-Id: <address@hidden>
Signed-off-by: Kevin Wolf <address@hidden>
---
block/qcow2.c | 23 +++++------------------
1 file changed, 5 insertions(+), 18 deletions(-)
diff --git a/block/qcow2.c b/block/qcow2.c
index c9306a7..2f73201 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -2438,33 +2438,20 @@ static coroutine_fn int
qcow2_co_write_zeroes(BlockDriverState *bs,
int tail = (sector_num + nb_sectors) % s->cluster_sectors;
if (head != 0 || tail != 0) {
- int64_t cl_end = -1;
+ int64_t cl_start = sector_num - head;
- sector_num -= head;
- nb_sectors += head;
+ assert(cl_start + s->cluster_sectors >= sector_num + nb_sectors);
- if (tail != 0) {
- nb_sectors += s->cluster_sectors - tail;
- }
+ sector_num = cl_start;
+ nb_sectors = s->cluster_sectors;
if (!is_zero_cluster(bs, sector_num)) {
return -ENOTSUP;
}
- if (nb_sectors > s->cluster_sectors) {
- /* Technically the request can cover 2 clusters, f.e. 4k write
- at s->cluster_sectors - 2k offset. One of these cluster can
- be zeroed, one unallocated */
- cl_end = sector_num + nb_sectors - s->cluster_sectors;
- if (!is_zero_cluster(bs, cl_end)) {
- return -ENOTSUP;
- }
- }
-
qemu_co_mutex_lock(&s->lock);
/* We can have new write after previous check */
- if (!is_zero_cluster_top_locked(bs, sector_num) ||
- (cl_end > 0 && !is_zero_cluster_top_locked(bs, cl_end))) {
+ if (!is_zero_cluster_top_locked(bs, sector_num)) {
qemu_co_mutex_unlock(&s->lock);
return -ENOTSUP;
}
--
1.8.3.1
- [Qemu-devel] [PULL 00/31] Block layer patches, Kevin Wolf, 2016/06/08
- [Qemu-devel] [PULL 06/31] iscsi: Use block size as minimum zero/discard alignment, Kevin Wolf, 2016/06/08
- [Qemu-devel] [PULL 02/31] qcow2: simplify logic in qcow2_co_write_zeroes,
Kevin Wolf <=
- [Qemu-devel] [PULL 07/31] block: Track write zero limits in bytes, Kevin Wolf, 2016/06/08
- [Qemu-devel] [PULL 08/31] block: Add .bdrv_co_pwrite_zeroes(), Kevin Wolf, 2016/06/08
- [Qemu-devel] [PULL 01/31] block: split write_zeroes always, Kevin Wolf, 2016/06/08
- [Qemu-devel] [PULL 03/31] qcow2: add tracepoints for qcow2_co_write_zeroes, Kevin Wolf, 2016/06/08
- [Qemu-devel] [PULL 10/31] iscsi: Convert to bdrv_co_pwrite_zeroes(), Kevin Wolf, 2016/06/08
- [Qemu-devel] [PULL 11/31] qcow2: Convert to bdrv_co_pwrite_zeroes(), Kevin Wolf, 2016/06/08
- [Qemu-devel] [PULL 05/31] qcow2: Catch more unaligned write_zero into zero cluster, Kevin Wolf, 2016/06/08
- [Qemu-devel] [PULL 17/31] vmdk: Convert to bdrv_co_pwrite_zeroes(), Kevin Wolf, 2016/06/08
- [Qemu-devel] [PULL 19/31] migration/block: Convert load to BlockBackend, Kevin Wolf, 2016/06/08
- [Qemu-devel] [PULL 09/31] block: Switch bdrv_write_zeroes() to byte interface, Kevin Wolf, 2016/06/08