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[Qemu-block] [PULL 24/29] qcow: Switch qcow_co_readv to byte-based calls
From: |
Kevin Wolf |
Subject: |
[Qemu-block] [PULL 24/29] qcow: Switch qcow_co_readv to byte-based calls |
Date: |
Fri, 29 Jun 2018 16:09:54 +0200 |
From: Eric Blake <address@hidden>
We are gradually moving away from sector-based interfaces, towards
byte-based. Make the change for the internals of the qcow
driver read function, by iterating over offset/bytes instead of
sector_num/nb_sectors, and with a rename of index_in_cluster and
repurposing of n to track bytes instead of sectors.
A later patch will then switch the qcow driver as a whole over
to byte-based operation.
Signed-off-by: Eric Blake <address@hidden>
Reviewed-by: Jeff Cody <address@hidden>
Signed-off-by: Kevin Wolf <address@hidden>
---
block/qcow.c | 42 ++++++++++++++++++++----------------------
1 file changed, 20 insertions(+), 22 deletions(-)
diff --git a/block/qcow.c b/block/qcow.c
index d7c385a91d..436ad518be 100644
--- a/block/qcow.c
+++ b/block/qcow.c
@@ -617,13 +617,15 @@ static coroutine_fn int qcow_co_readv(BlockDriverState
*bs, int64_t sector_num,
int nb_sectors, QEMUIOVector *qiov)
{
BDRVQcowState *s = bs->opaque;
- int index_in_cluster;
+ int offset_in_cluster;
int ret = 0, n;
uint64_t cluster_offset;
struct iovec hd_iov;
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;
if (qiov->niov > 1) {
buf = orig_buf = qemu_try_blockalign(bs, qiov->size);
@@ -637,36 +639,35 @@ static coroutine_fn int qcow_co_readv(BlockDriverState
*bs, int64_t sector_num,
qemu_co_mutex_lock(&s->lock);
- while (nb_sectors != 0) {
+ while (bytes != 0) {
/* prepare next request */
- ret = get_cluster_offset(bs, sector_num << 9,
- 0, 0, 0, 0, &cluster_offset);
+ ret = get_cluster_offset(bs, offset, 0, 0, 0, 0, &cluster_offset);
if (ret < 0) {
break;
}
- index_in_cluster = sector_num & (s->cluster_sectors - 1);
- n = s->cluster_sectors - index_in_cluster;
- if (n > nb_sectors) {
- n = nb_sectors;
+ offset_in_cluster = offset & (s->cluster_size - 1);
+ n = s->cluster_size - offset_in_cluster;
+ if (n > bytes) {
+ n = bytes;
}
if (!cluster_offset) {
if (bs->backing) {
/* read from the base image */
hd_iov.iov_base = (void *)buf;
- hd_iov.iov_len = n * 512;
+ hd_iov.iov_len = n;
qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
qemu_co_mutex_unlock(&s->lock);
/* qcow2 emits this on bs->file instead of bs->backing */
BLKDBG_EVENT(bs->file, BLKDBG_READ_BACKING_AIO);
- ret = bdrv_co_readv(bs->backing, sector_num, n, &hd_qiov);
+ ret = bdrv_co_preadv(bs->backing, offset, n, &hd_qiov, 0);
qemu_co_mutex_lock(&s->lock);
if (ret < 0) {
break;
}
} else {
/* Note: in this case, no need to wait */
- memset(buf, 0, 512 * n);
+ memset(buf, 0, n);
}
} else if (cluster_offset & QCOW_OFLAG_COMPRESSED) {
/* add AIO support for compressed blocks ? */
@@ -674,21 +675,19 @@ static coroutine_fn int qcow_co_readv(BlockDriverState
*bs, int64_t sector_num,
ret = -EIO;
break;
}
- memcpy(buf,
- s->cluster_cache + index_in_cluster * 512, 512 * n);
+ memcpy(buf, s->cluster_cache + offset_in_cluster, n);
} else {
if ((cluster_offset & 511) != 0) {
ret = -EIO;
break;
}
hd_iov.iov_base = (void *)buf;
- hd_iov.iov_len = n * 512;
+ hd_iov.iov_len = n;
qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
qemu_co_mutex_unlock(&s->lock);
BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO);
- ret = bdrv_co_readv(bs->file,
- (cluster_offset >> 9) + index_in_cluster,
- n, &hd_qiov);
+ ret = bdrv_co_preadv(bs->file, cluster_offset + offset_in_cluster,
+ n, &hd_qiov, 0);
qemu_co_mutex_lock(&s->lock);
if (ret < 0) {
break;
@@ -696,8 +695,7 @@ static coroutine_fn int qcow_co_readv(BlockDriverState *bs,
int64_t sector_num,
if (bs->encrypted) {
assert(s->crypto);
if (qcrypto_block_decrypt(s->crypto,
- sector_num * BDRV_SECTOR_SIZE, buf,
- n * BDRV_SECTOR_SIZE, NULL) < 0) {
+ offset, buf, n, NULL) < 0) {
ret = -EIO;
break;
}
@@ -705,9 +703,9 @@ static coroutine_fn int qcow_co_readv(BlockDriverState *bs,
int64_t sector_num,
}
ret = 0;
- nb_sectors -= n;
- sector_num += n;
- buf += n * 512;
+ bytes -= n;
+ offset += n;
+ buf += n;
}
qemu_co_mutex_unlock(&s->lock);
--
2.13.6
- [Qemu-block] [PULL 07/29] block: Convert .bdrv_truncate callback to coroutine_fn, (continued)
- [Qemu-block] [PULL 07/29] block: Convert .bdrv_truncate callback to coroutine_fn, Kevin Wolf, 2018/06/29
- [Qemu-block] [PULL 11/29] file-posix: Make .bdrv_co_truncate asynchronous, Kevin Wolf, 2018/06/29
- [Qemu-block] [PULL 09/29] block: Move bdrv_truncate() implementation to io.c, Kevin Wolf, 2018/06/29
- [Qemu-block] [PULL 13/29] block: Move request tracking to children in copy offloading, Kevin Wolf, 2018/06/29
- [Qemu-block] [PULL 12/29] qcow2: Remove dead check on !ret, Kevin Wolf, 2018/06/29
- [Qemu-block] [PULL 14/29] block/crypto: Simplify block_crypto_{open, create}_opts_init(), Kevin Wolf, 2018/06/29
- [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 <=
- [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, 2018/06/29
- [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