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[Qemu-block] [PULL 26/29] qcow: Switch to a byte-based driver
From: |
Kevin Wolf |
Subject: |
[Qemu-block] [PULL 26/29] qcow: Switch to a byte-based driver |
Date: |
Fri, 29 Jun 2018 16:09:56 +0200 |
From: Eric Blake <address@hidden>
We are gradually moving away from sector-based interfaces, towards
byte-based. The qcow driver is now ready to fully utilize the
byte-based callback interface, as long as we override the default
alignment to still be 512 (needed at least for asserts present
because of encryption, but easier to do everywhere than to audit
which sub-sector requests are handled correctly, especially since
we no longer recommend qcow for new disk images).
Signed-off-by: Eric Blake <address@hidden>
Reviewed-by: Jeff Cody <address@hidden>
Signed-off-by: Kevin Wolf <address@hidden>
---
block/qcow.c | 35 ++++++++++++++++++++---------------
1 file changed, 20 insertions(+), 15 deletions(-)
diff --git a/block/qcow.c b/block/qcow.c
index 8fe82ed58d..102d058d1c 100644
--- a/block/qcow.c
+++ b/block/qcow.c
@@ -70,7 +70,6 @@ typedef struct QCowHeader {
typedef struct BDRVQcowState {
int cluster_bits;
int cluster_size;
- int cluster_sectors;
int l2_bits;
int l2_size;
unsigned int l1_size;
@@ -235,7 +234,6 @@ static int qcow_open(BlockDriverState *bs, QDict *options,
int flags,
}
s->cluster_bits = header.cluster_bits;
s->cluster_size = 1 << s->cluster_bits;
- s->cluster_sectors = 1 << (s->cluster_bits - 9);
s->l2_bits = header.l2_bits;
s->l2_size = 1 << s->l2_bits;
bs->total_sectors = header.size / 512;
@@ -613,8 +611,18 @@ static int decompress_cluster(BlockDriverState *bs,
uint64_t cluster_offset)
return 0;
}
-static coroutine_fn int qcow_co_readv(BlockDriverState *bs, int64_t sector_num,
- int nb_sectors, QEMUIOVector *qiov)
+static void qcow_refresh_limits(BlockDriverState *bs, Error **errp)
+{
+ /* At least encrypted images require 512-byte alignment. Apply the
+ * limit universally, rather than just on encrypted images, as
+ * it's easier to let the block layer handle rounding than to
+ * audit this code further. */
+ bs->bl.request_alignment = BDRV_SECTOR_SIZE;
+}
+
+static coroutine_fn int qcow_co_preadv(BlockDriverState *bs, uint64_t offset,
+ uint64_t bytes, QEMUIOVector *qiov,
+ int flags)
{
BDRVQcowState *s = bs->opaque;
int offset_in_cluster;
@@ -624,9 +632,8 @@ static coroutine_fn int qcow_co_readv(BlockDriverState *bs,
int64_t sector_num,
QEMUIOVector hd_qiov;
uint8_t *buf;
void *orig_buf;
- int64_t offset = sector_num * BDRV_SECTOR_SIZE;
- int64_t bytes = nb_sectors * BDRV_SECTOR_SIZE;
+ assert(!flags);
if (qiov->niov > 1) {
buf = orig_buf = qemu_try_blockalign(bs, qiov->size);
if (buf == NULL) {
@@ -718,9 +725,9 @@ static coroutine_fn int qcow_co_readv(BlockDriverState *bs,
int64_t sector_num,
return ret;
}
-static coroutine_fn int qcow_co_writev(BlockDriverState *bs, int64_t
sector_num,
- int nb_sectors, QEMUIOVector *qiov,
- int flags)
+static coroutine_fn int qcow_co_pwritev(BlockDriverState *bs, uint64_t offset,
+ uint64_t bytes, QEMUIOVector *qiov,
+ int flags)
{
BDRVQcowState *s = bs->opaque;
int offset_in_cluster;
@@ -730,8 +737,6 @@ static coroutine_fn int qcow_co_writev(BlockDriverState
*bs, int64_t sector_num,
QEMUIOVector hd_qiov;
uint8_t *buf;
void *orig_buf;
- int64_t offset = sector_num * BDRV_SECTOR_SIZE;
- int64_t bytes = nb_sectors * BDRV_SECTOR_SIZE;
assert(!flags);
s->cluster_cache_offset = -1; /* disable compressed cache */
@@ -1104,8 +1109,7 @@ qcow_co_pwritev_compressed(BlockDriverState *bs, uint64_t
offset,
if (ret != Z_STREAM_END || out_len >= s->cluster_size) {
/* could not compress: write normal cluster */
- ret = qcow_co_writev(bs, offset >> BDRV_SECTOR_BITS,
- bytes >> BDRV_SECTOR_BITS, qiov, 0);
+ ret = qcow_co_pwritev(bs, offset, bytes, qiov, 0);
if (ret < 0) {
goto fail;
}
@@ -1190,9 +1194,10 @@ static BlockDriver bdrv_qcow = {
.bdrv_co_create_opts = qcow_co_create_opts,
.bdrv_has_zero_init = bdrv_has_zero_init_1,
.supports_backing = true,
+ .bdrv_refresh_limits = qcow_refresh_limits,
- .bdrv_co_readv = qcow_co_readv,
- .bdrv_co_writev = qcow_co_writev,
+ .bdrv_co_preadv = qcow_co_preadv,
+ .bdrv_co_pwritev = qcow_co_pwritev,
.bdrv_co_block_status = qcow_co_block_status,
.bdrv_make_empty = qcow_make_empty,
--
2.13.6
- [Qemu-block] [PULL 16/29] qcow2: Free allocated clusters on write error, (continued)
- [Qemu-block] [PULL 16/29] qcow2: Free allocated clusters on write error, Kevin Wolf, 2018/06/29
- [Qemu-block] [PULL 17/29] qemu-iotests: Test qcow2 not leaking clusters on write error, Kevin Wolf, 2018/06/29
- [Qemu-block] [PULL 18/29] file-posix: Implement co versions of discard/flush, Kevin Wolf, 2018/06/29
- [Qemu-block] [PULL 15/29] qemu-iotests: Update 026.out.nocache reference output, Kevin Wolf, 2018/06/29
- [Qemu-block] [PULL 24/29] qcow: Switch qcow_co_readv to byte-based calls, Kevin Wolf, 2018/06/29
- [Qemu-block] [PULL 21/29] file-posix: Fix EINTR handling, Kevin Wolf, 2018/06/29
- [Qemu-block] [PULL 20/29] iscsi: Don't blindly use designator length in response for memcpy, Kevin Wolf, 2018/06/29
- [Qemu-block] [PULL 22/29] parallels: Switch to byte-based calls, Kevin Wolf, 2018/06/29
- [Qemu-block] [PULL 23/29] qcow: Switch get_cluster_offset to be byte-based, Kevin Wolf, 2018/06/29
- [Qemu-block] [PULL 19/29] qcow2: Fix src_offset in copy offloading, Kevin Wolf, 2018/06/29
- [Qemu-block] [PULL 26/29] qcow: Switch to a byte-based driver,
Kevin Wolf <=
- [Qemu-block] [PULL 25/29] qcow: Switch qcow_co_writev to byte-based calls, Kevin Wolf, 2018/06/29
- [Qemu-block] [PULL 27/29] replication: Switch to byte-based calls, Kevin Wolf, 2018/06/29
- [Qemu-block] [PULL 28/29] vhdx: Switch to byte-based calls, Kevin Wolf, 2018/06/29
- [Qemu-block] [PULL 29/29] block: Remove unused sector-based vectored I/O, Kevin Wolf, 2018/06/29
- Re: [Qemu-block] [PULL 00/29] Block layer patches, Peter Maydell, 2018/06/30