[Qemu-devel] [PATCH v4 00/17] block: local qiov helper

[Qemu-devel] [PATCH v4 00/17] block: local qiov helper

[Vladimir Sementsov-Ogievskiy]

Hi all!

Here is a new simple helper for a very often patter
around qemu_iovec_init_external, when we need simple qiov with only
one iov, initialized from external buffer.

v4:
 01: tiny improvements by Eric
     + fix bug: s/niov/nalloc in assertion
     + rename s/qemu_iovec_get_buf/qemu_iovec_buf,
       to don't look like getter, which in turn should not return
       pointer to something internal to be freed separately.
     So, no r-b's in 01 
 07,10,16
    - rebase on new function name qemu_iovec_buf 
    - save r-b's by Eric and Stefan
 others unchanged, add r-b's by Eric and Stefan

v3:
  01-02: tiny improvements, described in patch-emails
  03-17: new patches

  Note: only hw/scsi/scsi-disk.c not updated, as it has too tricky
        logic around @iov fields of structures. So, it is simpler to
        keep it as is.

v2 was "[PATCH v2 0/2] block: local qiov helper: part I"
https://lists.gnu.org/archive/html/qemu-devel/2019-02/msg01610.html

Vladimir Sementsov-Ogievskiy (17):
  block: enhance QEMUIOVector structure
  block/io: use qemu_iovec_init_buf
  block/block-backend: use QEMU_IOVEC_INIT_BUF
  block/backup: use qemu_iovec_init_buf
  block/commit: use QEMU_IOVEC_INIT_BUF
  block/stream: use QEMU_IOVEC_INIT_BUF
  block/parallels: use QEMU_IOVEC_INIT_BUF
  block/qcow: use qemu_iovec_init_buf
  block/qcow2: use qemu_iovec_init_buf
  block/qed: use qemu_iovec_init_buf
  block/vmdk: use qemu_iovec_init_buf
  qemu-img: use qemu_iovec_init_buf
  migration/block: use qemu_iovec_init_buf
  tests/test-bdrv-drain: use QEMU_IOVEC_INIT_BUF
  hw/ide: drop iov field from IDEState
  hw/ide: drop iov field from IDEBufferedRequest
  hw/ide: drop iov field from IDEDMA

 include/hw/ide/internal.h |  3 --
 include/qemu/iov.h        | 64 +++++++++++++++++++++++++++-
 block/backup.c            |  5 +--
 block/block-backend.c     | 13 +-----
 block/commit.c            |  7 +--
 block/io.c                | 89 +++++++++------------------------------
 block/parallels.c         | 13 +++---
 block/qcow.c              | 21 ++-------
 block/qcow2.c             | 12 +-----
 block/qed-table.c         | 16 ++-----
 block/qed.c               | 31 ++++----------
 block/stream.c            |  7 +--
 block/vmdk.c              |  7 +--
 hw/ide/atapi.c            | 14 +++---
 hw/ide/core.c             | 19 ++++-----
 migration/block.c         | 10 ++---
 qemu-img.c                | 10 +----
 tests/test-bdrv-drain.c   | 29 ++-----------
 18 files changed, 134 insertions(+), 236 deletions(-)

-- 
2.18.0

[Qemu-devel] [PATCH v4 01/17] block: enhance QEMUIOVector structure

[Vladimir Sementsov-Ogievskiy]

Add a possibility of embedded iovec, for cases when we need only one
local iov.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 include/qemu/iov.h | 64 ++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 62 insertions(+), 2 deletions(-)

diff --git a/include/qemu/iov.h b/include/qemu/iov.h
index 5f433c7768..48b45987b7 100644
--- a/include/qemu/iov.h
+++ b/include/qemu/iov.h
@@ -133,10 +133,70 @@ size_t iov_discard_back(struct iovec *iov, unsigned int *iov_cnt,
 typedef struct QEMUIOVector {
     struct iovec *iov;
     int niov;
-    int nalloc;
-    size_t size;
+
+    /*
+     * For external @iov (qemu_iovec_init_external()) or allocated @iov
+     * (qemu_iovec_init()), @size is the cumulative size of iovecs and
+     * @local_iov is invalid and unused.
+     *
+     * For embedded @iov (QEMU_IOVEC_INIT_BUF() or qemu_iovec_init_buf()),
+     * @iov is equal to &@local_iov, and @size is valid, as it has same
+     * offset and type as @local_iov.iov_len, which is guaranteed by
+     * static assertion below.
+     *
+     * @nalloc is always valid and is -1 both for embedded and external
+     * cases. It is included in the union only to ensure the padding prior
+     * to the @size field will not result in a 0-length array.
+     */
+    union {
+        struct {
+            int nalloc;
+            struct iovec local_iov;
+        };
+        struct {
+            char __pad[sizeof(int) + offsetof(struct iovec, iov_len)];
+            size_t size;
+        };
+    };
 } QEMUIOVector;
 
+QEMU_BUILD_BUG_ON(offsetof(QEMUIOVector, size) !=
+                  offsetof(QEMUIOVector, local_iov.iov_len));
+
+#define QEMU_IOVEC_INIT_BUF(self, buf, len)              \
+{                                                        \
+    .iov = &(self).local_iov,                            \
+    .niov = 1,                                           \
+    .nalloc = -1,                                        \
+    .local_iov = {                                       \
+        .iov_base = (void *)(buf), /* cast away const */ \
+        .iov_len = (len),                                \
+    },                                                   \
+}
+
+/*
+ * qemu_iovec_init_buf
+ *
+ * Initialize embedded QEMUIOVector.
+ *
+ * Note: "const" is used over @buf pointer to make it simple to pass
+ * const pointers, appearing in read functions. Then this "const" is
+ * cast away by QEMU_IOVEC_INIT_BUF().
+ */
+static inline void qemu_iovec_init_buf(QEMUIOVector *qiov,
+                                       const void *buf, size_t len)
+{
+    *qiov = (QEMUIOVector) QEMU_IOVEC_INIT_BUF(*qiov, buf, len);
+}
+
+static inline void *qemu_iovec_buf(QEMUIOVector *qiov)
+{
+    /* Only supports embedded iov */
+    assert(qiov->nalloc == -1 && qiov->iov == &qiov->local_iov);
+
+    return qiov->local_iov.iov_base;
+}
+
 void qemu_iovec_init(QEMUIOVector *qiov, int alloc_hint);
 void qemu_iovec_init_external(QEMUIOVector *qiov, struct iovec *iov, int niov);
 void qemu_iovec_add(QEMUIOVector *qiov, void *base, size_t len);
-- 
2.18.0

Re: [Qemu-devel] [PATCH v4 01/17] block: enhance QEMUIOVector structure

[Eric Blake]

On 2/18/19 8:09 AM, Vladimir Sementsov-Ogievskiy wrote:
> Add a possibility of embedded iovec, for cases when we need only one
> local iov.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> ---
>  include/qemu/iov.h | 64 ++++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 62 insertions(+), 2 deletions(-)
> 

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

[Qemu-devel] [PATCH v4 02/17] block/io: use qemu_iovec_init_buf

[Vladimir Sementsov-Ogievskiy]

Use new qemu_iovec_init_buf() instead of
qemu_iovec_init_external( ... , 1), which simplifies the code.

While being here, use qemu_try_blockalign0 as well.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 block/io.c | 89 ++++++++++++------------------------------------------
 1 file changed, 20 insertions(+), 69 deletions(-)

diff --git a/block/io.c b/block/io.c
index 213ca03d8d..2ba603c7bc 100644
--- a/block/io.c
+++ b/block/io.c
@@ -843,17 +843,13 @@ static int bdrv_prwv_co(BdrvChild *child, int64_t offset,
 static int bdrv_rw_co(BdrvChild *child, int64_t sector_num, uint8_t *buf,
                       int nb_sectors, bool is_write, BdrvRequestFlags flags)
 {
-    QEMUIOVector qiov;
-    struct iovec iov = {
-        .iov_base = (void *)buf,
-        .iov_len = nb_sectors * BDRV_SECTOR_SIZE,
-    };
+    QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf,
+                                            nb_sectors * BDRV_SECTOR_SIZE);
 
     if (nb_sectors < 0 || nb_sectors > BDRV_REQUEST_MAX_SECTORS) {
         return -EINVAL;
     }
 
-    qemu_iovec_init_external(&qiov, &iov, 1);
     return bdrv_prwv_co(child, sector_num << BDRV_SECTOR_BITS,
                         &qiov, is_write, flags);
 }
@@ -880,13 +876,8 @@ int bdrv_write(BdrvChild *child, int64_t sector_num,
 int bdrv_pwrite_zeroes(BdrvChild *child, int64_t offset,
                        int bytes, BdrvRequestFlags flags)
 {
-    QEMUIOVector qiov;
-    struct iovec iov = {
-        .iov_base = NULL,
-        .iov_len = bytes,
-    };
+    QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, NULL, bytes);
 
-    qemu_iovec_init_external(&qiov, &iov, 1);
     return bdrv_prwv_co(child, offset, &qiov, true,
                         BDRV_REQ_ZERO_WRITE | flags);
 }
@@ -950,17 +941,12 @@ int bdrv_preadv(BdrvChild *child, int64_t offset, QEMUIOVector *qiov)
 
 int bdrv_pread(BdrvChild *child, int64_t offset, void *buf, int bytes)
 {
-    QEMUIOVector qiov;
-    struct iovec iov = {
-        .iov_base = (void *)buf,
-        .iov_len = bytes,
-    };
+    QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes);
 
     if (bytes < 0) {
         return -EINVAL;
     }
 
-    qemu_iovec_init_external(&qiov, &iov, 1);
     return bdrv_preadv(child, offset, &qiov);
 }
 
@@ -978,17 +964,12 @@ int bdrv_pwritev(BdrvChild *child, int64_t offset, QEMUIOVector *qiov)
 
 int bdrv_pwrite(BdrvChild *child, int64_t offset, const void *buf, int bytes)
 {
-    QEMUIOVector qiov;
-    struct iovec iov = {
-        .iov_base   = (void *) buf,
-        .iov_len    = bytes,
-    };
+    QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes);
 
     if (bytes < 0) {
         return -EINVAL;
     }
 
-    qemu_iovec_init_external(&qiov, &iov, 1);
     return bdrv_pwritev(child, offset, &qiov);
 }
 
@@ -1165,7 +1146,6 @@ static int coroutine_fn bdrv_co_do_copy_on_readv(BdrvChild *child,
     void *bounce_buffer;
 
     BlockDriver *drv = bs->drv;
-    struct iovec iov;
     QEMUIOVector local_qiov;
     int64_t cluster_offset;
     int64_t cluster_bytes;
@@ -1230,9 +1210,8 @@ static int coroutine_fn bdrv_co_do_copy_on_readv(BdrvChild *child,
 
         if (ret <= 0) {
             /* Must copy-on-read; use the bounce buffer */
-            iov.iov_base = bounce_buffer;
-            iov.iov_len = pnum = MIN(pnum, MAX_BOUNCE_BUFFER);
-            qemu_iovec_init_external(&local_qiov, &iov, 1);
+            pnum = MIN(pnum, MAX_BOUNCE_BUFFER);
+            qemu_iovec_init_buf(&local_qiov, bounce_buffer, pnum);
 
             ret = bdrv_driver_preadv(bs, cluster_offset, pnum,
                                      &local_qiov, 0);
@@ -1477,7 +1456,7 @@ static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs,
 {
     BlockDriver *drv = bs->drv;
     QEMUIOVector qiov;
-    struct iovec iov = {0};
+    void *buf = NULL;
     int ret = 0;
     bool need_flush = false;
     int head = 0;
@@ -1547,16 +1526,14 @@ static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs,
                 need_flush = true;
             }
             num = MIN(num, max_transfer);
-            iov.iov_len = num;
-            if (iov.iov_base == NULL) {
-                iov.iov_base = qemu_try_blockalign(bs, num);
-                if (iov.iov_base == NULL) {
+            if (buf == NULL) {
+                buf = qemu_try_blockalign0(bs, num);
+                if (buf == NULL) {
                     ret = -ENOMEM;
                     goto fail;
                 }
-                memset(iov.iov_base, 0, num);
             }
-            qemu_iovec_init_external(&qiov, &iov, 1);
+            qemu_iovec_init_buf(&qiov, buf, num);
 
             ret = bdrv_driver_pwritev(bs, offset, num, &qiov, write_flags);
 
@@ -1564,8 +1541,8 @@ static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs,
              * all future requests.
              */
             if (num < max_transfer) {
-                qemu_vfree(iov.iov_base);
-                iov.iov_base = NULL;
+                qemu_vfree(buf);
+                buf = NULL;
             }
         }
 
@@ -1577,7 +1554,7 @@ fail:
     if (ret == 0 && need_flush) {
         ret = bdrv_co_flush(bs);
     }
-    qemu_vfree(iov.iov_base);
+    qemu_vfree(buf);
     return ret;
 }
 
@@ -1763,7 +1740,6 @@ static int coroutine_fn bdrv_co_do_zero_pwritev(BdrvChild *child,
     BlockDriverState *bs = child->bs;
     uint8_t *buf = NULL;
     QEMUIOVector local_qiov;
-    struct iovec iov;
     uint64_t align = bs->bl.request_alignment;
     unsigned int head_padding_bytes, tail_padding_bytes;
     int ret = 0;
@@ -1775,11 +1751,7 @@ static int coroutine_fn bdrv_co_do_zero_pwritev(BdrvChild *child,
     assert(flags & BDRV_REQ_ZERO_WRITE);
     if (head_padding_bytes || tail_padding_bytes) {
         buf = qemu_blockalign(bs, align);
-        iov = (struct iovec) {
-            .iov_base   = buf,
-            .iov_len    = align,
-        };
-        qemu_iovec_init_external(&local_qiov, &iov, 1);
+        qemu_iovec_init_buf(&local_qiov, buf, align);
     }
     if (head_padding_bytes) {
         uint64_t zero_bytes = MIN(bytes, align - head_padding_bytes);
@@ -1885,17 +1857,12 @@ int coroutine_fn bdrv_co_pwritev(BdrvChild *child,
 
     if (offset & (align - 1)) {
         QEMUIOVector head_qiov;
-        struct iovec head_iov;
 
         mark_request_serialising(&req, align);
         wait_serialising_requests(&req);
 
         head_buf = qemu_blockalign(bs, align);
-        head_iov = (struct iovec) {
-            .iov_base   = head_buf,
-            .iov_len    = align,
-        };
-        qemu_iovec_init_external(&head_qiov, &head_iov, 1);
+        qemu_iovec_init_buf(&head_qiov, head_buf, align);
 
         bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_HEAD);
         ret = bdrv_aligned_preadv(child, &req, offset & ~(align - 1), align,
@@ -1924,7 +1891,6 @@ int coroutine_fn bdrv_co_pwritev(BdrvChild *child,
 
     if ((offset + bytes) & (align - 1)) {
         QEMUIOVector tail_qiov;
-        struct iovec tail_iov;
         size_t tail_bytes;
         bool waited;
 
@@ -1933,11 +1899,7 @@ int coroutine_fn bdrv_co_pwritev(BdrvChild *child,
         assert(!waited || !use_local_qiov);
 
         tail_buf = qemu_blockalign(bs, align);
-        tail_iov = (struct iovec) {
-            .iov_base   = tail_buf,
-            .iov_len    = align,
-        };
-        qemu_iovec_init_external(&tail_qiov, &tail_iov, 1);
+        qemu_iovec_init_buf(&tail_qiov, tail_buf, align);
 
         bdrv_debug_event(bs, BLKDBG_PWRITEV_RMW_TAIL);
         ret = bdrv_aligned_preadv(child, &req, (offset + bytes) & ~(align - 1),
@@ -2468,15 +2430,9 @@ bdrv_rw_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos,
 int bdrv_save_vmstate(BlockDriverState *bs, const uint8_t *buf,
                       int64_t pos, int size)
 {
-    QEMUIOVector qiov;
-    struct iovec iov = {
-        .iov_base   = (void *) buf,
-        .iov_len    = size,
-    };
+    QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, size);
     int ret;
 
-    qemu_iovec_init_external(&qiov, &iov, 1);
-
     ret = bdrv_writev_vmstate(bs, &qiov, pos);
     if (ret < 0) {
         return ret;
@@ -2493,14 +2449,9 @@ int bdrv_writev_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos)
 int bdrv_load_vmstate(BlockDriverState *bs, uint8_t *buf,
                       int64_t pos, int size)
 {
-    QEMUIOVector qiov;
-    struct iovec iov = {
-        .iov_base   = buf,
-        .iov_len    = size,
-    };
+    QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, size);
     int ret;
 
-    qemu_iovec_init_external(&qiov, &iov, 1);
     ret = bdrv_readv_vmstate(bs, &qiov, pos);
     if (ret < 0) {
         return ret;
-- 
2.18.0

[Qemu-devel] [PATCH v4 03/17] block/block-backend: use QEMU_IOVEC_INIT_BUF

[Vladimir Sementsov-Ogievskiy]

Use new QEMU_IOVEC_INIT_BUF() instead of
qemu_iovec_init_external( ... , 1), which simplifies the code.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 block/block-backend.c | 13 ++-----------
 1 file changed, 2 insertions(+), 11 deletions(-)

diff --git a/block/block-backend.c b/block/block-backend.c
index f6ea824308..6cc25569ef 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -1204,17 +1204,8 @@ static int blk_prw(BlockBackend *blk, int64_t offset, uint8_t *buf,
                    int64_t bytes, CoroutineEntry co_entry,
                    BdrvRequestFlags flags)
 {
-    QEMUIOVector qiov;
-    struct iovec iov;
-    BlkRwCo rwco;
-
-    iov = (struct iovec) {
-        .iov_base = buf,
-        .iov_len = bytes,
-    };
-    qemu_iovec_init_external(&qiov, &iov, 1);
-
-    rwco = (BlkRwCo) {
+    QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes);
+    BlkRwCo rwco = {
         .blk    = blk,
         .offset = offset,
         .iobuf  = &qiov,
-- 
2.18.0

[Qemu-devel] [PATCH v4 04/17] block/backup: use qemu_iovec_init_buf

[Vladimir Sementsov-Ogievskiy]

Use new qemu_iovec_init_buf() instead of
qemu_iovec_init_external( ... , 1), which simplifies the code.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 block/backup.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/block/backup.c b/block/backup.c
index 435414e964..9988753249 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -107,7 +107,6 @@ static int coroutine_fn backup_cow_with_bounce_buffer(BackupBlockJob *job,
                                                       void **bounce_buffer)
 {
     int ret;
-    struct iovec iov;
     QEMUIOVector qiov;
     BlockBackend *blk = job->common.blk;
     int nbytes;
@@ -119,9 +118,7 @@ static int coroutine_fn backup_cow_with_bounce_buffer(BackupBlockJob *job,
     if (!*bounce_buffer) {
         *bounce_buffer = blk_blockalign(blk, job->cluster_size);
     }
-    iov.iov_base = *bounce_buffer;
-    iov.iov_len = nbytes;
-    qemu_iovec_init_external(&qiov, &iov, 1);
+    qemu_iovec_init_buf(&qiov, *bounce_buffer, nbytes);
 
     ret = blk_co_preadv(blk, start, qiov.size, &qiov, read_flags);
     if (ret < 0) {
-- 
2.18.0

[Qemu-devel] [PATCH v4 05/17] block/commit: use QEMU_IOVEC_INIT_BUF

[Vladimir Sementsov-Ogievskiy]

Use new QEMU_IOVEC_INIT_BUF() instead of
qemu_iovec_init_external( ... , 1), which simplifies the code.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 block/commit.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/block/commit.c b/block/commit.c
index 53148e610b..d500a93068 100644
--- a/block/commit.c
+++ b/block/commit.c
@@ -47,14 +47,9 @@ static int coroutine_fn commit_populate(BlockBackend *bs, BlockBackend *base,
                                         void *buf)
 {
     int ret = 0;
-    QEMUIOVector qiov;
-    struct iovec iov = {
-        .iov_base = buf,
-        .iov_len = bytes,
-    };
+    QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes);
 
     assert(bytes < SIZE_MAX);
-    qemu_iovec_init_external(&qiov, &iov, 1);
 
     ret = blk_co_preadv(bs, offset, qiov.size, &qiov, 0);
     if (ret < 0) {
-- 
2.18.0

[Qemu-devel] [PATCH v4 06/17] block/stream: use QEMU_IOVEC_INIT_BUF

[Vladimir Sementsov-Ogievskiy]

Use new QEMU_IOVEC_INIT_BUF() instead of
qemu_iovec_init_external( ... , 1), which simplifies the code.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 block/stream.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/block/stream.c b/block/stream.c
index 7a49ac0992..e14579ff80 100644
--- a/block/stream.c
+++ b/block/stream.c
@@ -41,14 +41,9 @@ static int coroutine_fn stream_populate(BlockBackend *blk,
                                         int64_t offset, uint64_t bytes,
                                         void *buf)
 {
-    struct iovec iov = {
-        .iov_base = buf,
-        .iov_len  = bytes,
-    };
-    QEMUIOVector qiov;
+    QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buf, bytes);
 
     assert(bytes < SIZE_MAX);
-    qemu_iovec_init_external(&qiov, &iov, 1);
 
     /* Copy-on-read the unallocated clusters */
     return blk_co_preadv(blk, offset, qiov.size, &qiov, BDRV_REQ_COPY_ON_READ);
-- 
2.18.0

[Qemu-devel] [PATCH v4 07/17] block/parallels: use QEMU_IOVEC_INIT_BUF

[Vladimir Sementsov-Ogievskiy]

Use new QEMU_IOVEC_INIT_BUF() instead of
qemu_iovec_init_external( ... , 1), which simplifies the code.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 block/parallels.c | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/block/parallels.c b/block/parallels.c
index cc9445879d..15bc97b759 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -220,23 +220,20 @@ static int64_t allocate_clusters(BlockDriverState *bs, int64_t sector_num,
     if (bs->backing) {
         int64_t nb_cow_sectors = to_allocate * s->tracks;
         int64_t nb_cow_bytes = nb_cow_sectors << BDRV_SECTOR_BITS;
-        QEMUIOVector qiov;
-        struct iovec iov = {
-            .iov_len = nb_cow_bytes,
-            .iov_base = qemu_blockalign(bs, nb_cow_bytes)
-        };
-        qemu_iovec_init_external(&qiov, &iov, 1);
+        QEMUIOVector qiov =
+            QEMU_IOVEC_INIT_BUF(qiov, qemu_blockalign(bs, nb_cow_bytes),
+                                nb_cow_bytes);
 
         ret = bdrv_co_preadv(bs->backing, idx * s->tracks * BDRV_SECTOR_SIZE,
                              nb_cow_bytes, &qiov, 0);
         if (ret < 0) {
-            qemu_vfree(iov.iov_base);
+            qemu_vfree(qemu_iovec_buf(&qiov));
             return ret;
         }
 
         ret = bdrv_co_pwritev(bs->file, s->data_end * BDRV_SECTOR_SIZE,
                               nb_cow_bytes, &qiov, 0);
-        qemu_vfree(iov.iov_base);
+        qemu_vfree(qemu_iovec_buf(&qiov));
         if (ret < 0) {
             return ret;
         }
-- 
2.18.0

[Qemu-devel] [PATCH v4 08/17] block/qcow: use qemu_iovec_init_buf

[Vladimir Sementsov-Ogievskiy]

Use new qemu_iovec_init_buf() instead of
qemu_iovec_init_external( ... , 1), which simplifies the code.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 block/qcow.c | 21 ++++-----------------
 1 file changed, 4 insertions(+), 17 deletions(-)

diff --git a/block/qcow.c b/block/qcow.c
index 0a235bf393..409c700d33 100644
--- a/block/qcow.c
+++ b/block/qcow.c
@@ -628,7 +628,6 @@ static coroutine_fn int qcow_co_preadv(BlockDriverState *bs, uint64_t offset,
     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;
@@ -661,9 +660,7 @@ static coroutine_fn int qcow_co_preadv(BlockDriverState *bs, uint64_t offset,
         if (!cluster_offset) {
             if (bs->backing) {
                 /* read from the base image */
-                hd_iov.iov_base = (void *)buf;
-                hd_iov.iov_len = n;
-                qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
+                qemu_iovec_init_buf(&hd_qiov, buf, n);
                 qemu_co_mutex_unlock(&s->lock);
                 /* qcow2 emits this on bs->file instead of bs->backing */
                 BLKDBG_EVENT(bs->file, BLKDBG_READ_BACKING_AIO);
@@ -688,9 +685,7 @@ static coroutine_fn int qcow_co_preadv(BlockDriverState *bs, uint64_t offset,
                 ret = -EIO;
                 break;
             }
-            hd_iov.iov_base = (void *)buf;
-            hd_iov.iov_len = n;
-            qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
+            qemu_iovec_init_buf(&hd_qiov, buf, n);
             qemu_co_mutex_unlock(&s->lock);
             BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO);
             ret = bdrv_co_preadv(bs->file, cluster_offset + offset_in_cluster,
@@ -733,7 +728,6 @@ static coroutine_fn int qcow_co_pwritev(BlockDriverState *bs, uint64_t offset,
     int offset_in_cluster;
     uint64_t cluster_offset;
     int ret = 0, n;
-    struct iovec hd_iov;
     QEMUIOVector hd_qiov;
     uint8_t *buf;
     void *orig_buf;
@@ -779,9 +773,7 @@ static coroutine_fn int qcow_co_pwritev(BlockDriverState *bs, uint64_t offset,
             }
         }
 
-        hd_iov.iov_base = (void *)buf;
-        hd_iov.iov_len = n;
-        qemu_iovec_init_external(&hd_qiov, &hd_iov, 1);
+        qemu_iovec_init_buf(&hd_qiov, buf, n);
         qemu_co_mutex_unlock(&s->lock);
         BLKDBG_EVENT(bs->file, BLKDBG_WRITE_AIO);
         ret = bdrv_co_pwritev(bs->file, cluster_offset + offset_in_cluster,
@@ -1062,7 +1054,6 @@ qcow_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset,
 {
     BDRVQcowState *s = bs->opaque;
     QEMUIOVector hd_qiov;
-    struct iovec iov;
     z_stream strm;
     int ret, out_len;
     uint8_t *buf, *out_buf;
@@ -1128,11 +1119,7 @@ qcow_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset,
     }
     cluster_offset &= s->cluster_offset_mask;
 
-    iov = (struct iovec) {
-        .iov_base   = out_buf,
-        .iov_len    = out_len,
-    };
-    qemu_iovec_init_external(&hd_qiov, &iov, 1);
+    qemu_iovec_init_buf(&hd_qiov, out_buf, out_len);
     BLKDBG_EVENT(bs->file, BLKDBG_WRITE_COMPRESSED);
     ret = bdrv_co_pwritev(bs->file, cluster_offset, out_len, &hd_qiov, 0);
     if (ret < 0) {
-- 
2.18.0

[Qemu-devel] [PATCH v4 09/17] block/qcow2: use qemu_iovec_init_buf

[Vladimir Sementsov-Ogievskiy]

Use new qemu_iovec_init_buf() instead of
qemu_iovec_init_external( ... , 1), which simplifies the code.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 block/qcow2.c | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/block/qcow2.c b/block/qcow2.c
index 65a54c9ac6..b6d475229e 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -3894,7 +3894,6 @@ qcow2_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset,
 {
     BDRVQcow2State *s = bs->opaque;
     QEMUIOVector hd_qiov;
-    struct iovec iov;
     int ret;
     size_t out_len;
     uint8_t *buf, *out_buf;
@@ -3960,11 +3959,7 @@ qcow2_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset,
         goto fail;
     }
 
-    iov = (struct iovec) {
-        .iov_base   = out_buf,
-        .iov_len    = out_len,
-    };
-    qemu_iovec_init_external(&hd_qiov, &iov, 1);
+    qemu_iovec_init_buf(&hd_qiov, out_buf, out_len);
 
     BLKDBG_EVENT(bs->file, BLKDBG_WRITE_COMPRESSED);
     ret = bdrv_co_pwritev(bs->file, cluster_offset, out_len, &hd_qiov, 0);
@@ -3990,7 +3985,6 @@ qcow2_co_preadv_compressed(BlockDriverState *bs,
     int ret = 0, csize, nb_csectors;
     uint64_t coffset;
     uint8_t *buf, *out_buf;
-    struct iovec iov;
     QEMUIOVector local_qiov;
     int offset_in_cluster = offset_into_cluster(s, offset);
 
@@ -4002,9 +3996,7 @@ qcow2_co_preadv_compressed(BlockDriverState *bs,
     if (!buf) {
         return -ENOMEM;
     }
-    iov.iov_base = buf;
-    iov.iov_len = csize;
-    qemu_iovec_init_external(&local_qiov, &iov, 1);
+    qemu_iovec_init_buf(&local_qiov, buf, csize);
 
     out_buf = qemu_blockalign(bs, s->cluster_size);
 
-- 
2.18.0

[Qemu-devel] [PATCH v4 10/17] block/qed: use qemu_iovec_init_buf

[Vladimir Sementsov-Ogievskiy]

Use new qemu_iovec_init_buf() instead of
qemu_iovec_init_external( ... , 1), which simplifies the code.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 block/qed-table.c | 16 +++-------------
 block/qed.c       | 31 +++++++++----------------------
 2 files changed, 12 insertions(+), 35 deletions(-)

diff --git a/block/qed-table.c b/block/qed-table.c
index 7df5680adb..c497bd4aec 100644
--- a/block/qed-table.c
+++ b/block/qed-table.c
@@ -21,16 +21,11 @@
 /* Called with table_lock held.  */
 static int qed_read_table(BDRVQEDState *s, uint64_t offset, QEDTable *table)
 {
-    QEMUIOVector qiov;
+    QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(
+        qiov, table->offsets, s->header.cluster_size * s->header.table_size);
     int noffsets;
     int i, ret;
 
-    struct iovec iov = {
-        .iov_base = table->offsets,
-        .iov_len = s->header.cluster_size * s->header.table_size,
-    };
-    qemu_iovec_init_external(&qiov, &iov, 1);
-
     trace_qed_read_table(s, offset, table);
 
     qemu_co_mutex_unlock(&s->table_lock);
@@ -71,7 +66,6 @@ static int qed_write_table(BDRVQEDState *s, uint64_t offset, QEDTable *table,
     unsigned int sector_mask = BDRV_SECTOR_SIZE / sizeof(uint64_t) - 1;
     unsigned int start, end, i;
     QEDTable *new_table;
-    struct iovec iov;
     QEMUIOVector qiov;
     size_t len_bytes;
     int ret;
@@ -85,11 +79,7 @@ static int qed_write_table(BDRVQEDState *s, uint64_t offset, QEDTable *table,
     len_bytes = (end - start) * sizeof(uint64_t);
 
     new_table = qemu_blockalign(s->bs, len_bytes);
-    iov = (struct iovec) {
-        .iov_base = new_table->offsets,
-        .iov_len = len_bytes,
-    };
-    qemu_iovec_init_external(&qiov, &iov, 1);
+    qemu_iovec_init_buf(&qiov, new_table->offsets, len_bytes);
 
     /* Byteswap table */
     for (i = start; i < end; i++) {
diff --git a/block/qed.c b/block/qed.c
index 1280870024..c5e6d6ad41 100644
--- a/block/qed.c
+++ b/block/qed.c
@@ -113,18 +113,13 @@ static int coroutine_fn qed_write_header(BDRVQEDState *s)
     int nsectors = DIV_ROUND_UP(sizeof(QEDHeader), BDRV_SECTOR_SIZE);
     size_t len = nsectors * BDRV_SECTOR_SIZE;
     uint8_t *buf;
-    struct iovec iov;
     QEMUIOVector qiov;
     int ret;
 
     assert(s->allocating_acb || s->allocating_write_reqs_plugged);
 
     buf = qemu_blockalign(s->bs, len);
-    iov = (struct iovec) {
-        .iov_base = buf,
-        .iov_len = len,
-    };
-    qemu_iovec_init_external(&qiov, &iov, 1);
+    qemu_iovec_init_buf(&qiov, buf, len);
 
     ret = bdrv_co_preadv(s->bs->file, 0, qiov.size, &qiov, 0);
     if (ret < 0) {
@@ -913,7 +908,6 @@ static int coroutine_fn qed_copy_from_backing_file(BDRVQEDState *s,
 {
     QEMUIOVector qiov;
     QEMUIOVector *backing_qiov = NULL;
-    struct iovec iov;
     int ret;
 
     /* Skip copy entirely if there is no work to do */
@@ -921,11 +915,7 @@ static int coroutine_fn qed_copy_from_backing_file(BDRVQEDState *s,
         return 0;
     }
 
-    iov = (struct iovec) {
-        .iov_base = qemu_blockalign(s->bs, len),
-        .iov_len = len,
-    };
-    qemu_iovec_init_external(&qiov, &iov, 1);
+    qemu_iovec_init_buf(&qiov, qemu_blockalign(s->bs, len), len);
 
     ret = qed_read_backing_file(s, pos, &qiov, &backing_qiov);
 
@@ -946,7 +936,7 @@ static int coroutine_fn qed_copy_from_backing_file(BDRVQEDState *s,
     }
     ret = 0;
 out:
-    qemu_vfree(iov.iov_base);
+    qemu_vfree(qemu_iovec_buf(&qiov));
     return ret;
 }
 
@@ -1447,8 +1437,12 @@ static int coroutine_fn bdrv_qed_co_pwrite_zeroes(BlockDriverState *bs,
                                                   BdrvRequestFlags flags)
 {
     BDRVQEDState *s = bs->opaque;
-    QEMUIOVector qiov;
-    struct iovec iov;
+
+    /*
+     * Zero writes start without an I/O buffer.  If a buffer becomes necessary
+     * then it will be allocated during request processing.
+     */
+    QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, NULL, bytes);
 
     /* Fall back if the request is not aligned */
     if (qed_offset_into_cluster(s, offset) ||
@@ -1456,13 +1450,6 @@ static int coroutine_fn bdrv_qed_co_pwrite_zeroes(BlockDriverState *bs,
         return -ENOTSUP;
     }
 
-    /* Zero writes start without an I/O buffer.  If a buffer becomes necessary
-     * then it will be allocated during request processing.
-     */
-    iov.iov_base = NULL;
-    iov.iov_len = bytes;
-
-    qemu_iovec_init_external(&qiov, &iov, 1);
     return qed_co_request(bs, offset >> BDRV_SECTOR_BITS, &qiov,
                           bytes >> BDRV_SECTOR_BITS,
                           QED_AIOCB_WRITE | QED_AIOCB_ZERO);
-- 
2.18.0

[Qemu-devel] [PATCH v4 11/17] block/vmdk: use qemu_iovec_init_buf

[Vladimir Sementsov-Ogievskiy]

Use new qemu_iovec_init_buf() instead of
qemu_iovec_init_external( ... , 1), which simplifies the code.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 block/vmdk.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/block/vmdk.c b/block/vmdk.c
index 096e8eb662..41048741cd 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -1371,7 +1371,6 @@ static int vmdk_write_extent(VmdkExtent *extent, int64_t cluster_offset,
     VmdkGrainMarker *data = NULL;
     uLongf buf_len;
     QEMUIOVector local_qiov;
-    struct iovec iov;
     int64_t write_offset;
     int64_t write_end_sector;
 
@@ -1399,11 +1398,7 @@ static int vmdk_write_extent(VmdkExtent *extent, int64_t cluster_offset,
         data->size = cpu_to_le32(buf_len);
 
         n_bytes = buf_len + sizeof(VmdkGrainMarker);
-        iov = (struct iovec) {
-            .iov_base   = data,
-            .iov_len    = n_bytes,
-        };
-        qemu_iovec_init_external(&local_qiov, &iov, 1);
+        qemu_iovec_init_buf(&local_qiov, data, n_bytes);
 
         BLKDBG_EVENT(extent->file, BLKDBG_WRITE_COMPRESSED);
     } else {
-- 
2.18.0

[Qemu-devel] [PATCH v4 12/17] qemu-img: use qemu_iovec_init_buf

[Vladimir Sementsov-Ogievskiy]

Use new qemu_iovec_init_buf() instead of
qemu_iovec_init_external( ... , 1), which simplifies the code.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 qemu-img.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/qemu-img.c b/qemu-img.c
index 25288c4d18..7853935049 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -1670,7 +1670,6 @@ static int coroutine_fn convert_co_read(ImgConvertState *s, int64_t sector_num,
 {
     int n, ret;
     QEMUIOVector qiov;
-    struct iovec iov;
 
     assert(nb_sectors <= s->buf_sectors);
     while (nb_sectors > 0) {
@@ -1686,9 +1685,7 @@ static int coroutine_fn convert_co_read(ImgConvertState *s, int64_t sector_num,
         bs_sectors = s->src_sectors[src_cur];
 
         n = MIN(nb_sectors, bs_sectors - (sector_num - src_cur_offset));
-        iov.iov_base = buf;
-        iov.iov_len = n << BDRV_SECTOR_BITS;
-        qemu_iovec_init_external(&qiov, &iov, 1);
+        qemu_iovec_init_buf(&qiov, buf, n << BDRV_SECTOR_BITS);
 
         ret = blk_co_preadv(
                 blk, (sector_num - src_cur_offset) << BDRV_SECTOR_BITS,
@@ -1712,7 +1709,6 @@ static int coroutine_fn convert_co_write(ImgConvertState *s, int64_t sector_num,
 {
     int ret;
     QEMUIOVector qiov;
-    struct iovec iov;
 
     while (nb_sectors > 0) {
         int n = nb_sectors;
@@ -1740,9 +1736,7 @@ static int coroutine_fn convert_co_write(ImgConvertState *s, int64_t sector_num,
                 (s->compressed &&
                  !buffer_is_zero(buf, n * BDRV_SECTOR_SIZE)))
             {
-                iov.iov_base = buf;
-                iov.iov_len = n << BDRV_SECTOR_BITS;
-                qemu_iovec_init_external(&qiov, &iov, 1);
+                qemu_iovec_init_buf(&qiov, buf, n << BDRV_SECTOR_BITS);
 
                 ret = blk_co_pwritev(s->target, sector_num << BDRV_SECTOR_BITS,
                                      n << BDRV_SECTOR_BITS, &qiov, flags);
-- 
2.18.0

[Qemu-devel] [PATCH v4 13/17] migration/block: use qemu_iovec_init_buf

[Vladimir Sementsov-Ogievskiy]

Use new qemu_iovec_init_buf() instead of
qemu_iovec_init_external( ... , 1), which simplifies the code.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 migration/block.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/migration/block.c b/migration/block.c
index 0e24e18d13..83c633fb3f 100644
--- a/migration/block.c
+++ b/migration/block.c
@@ -83,7 +83,6 @@ typedef struct BlkMigBlock {
     BlkMigDevState *bmds;
     int64_t sector;
     int nr_sectors;
-    struct iovec iov;
     QEMUIOVector qiov;
     BlockAIOCB *aiocb;
 
@@ -314,9 +313,7 @@ static int mig_save_device_bulk(QEMUFile *f, BlkMigDevState *bmds)
     blk->sector = cur_sector;
     blk->nr_sectors = nr_sectors;
 
-    blk->iov.iov_base = blk->buf;
-    blk->iov.iov_len = nr_sectors * BDRV_SECTOR_SIZE;
-    qemu_iovec_init_external(&blk->qiov, &blk->iov, 1);
+    qemu_iovec_init_buf(&blk->qiov, blk->buf, nr_sectors * BDRV_SECTOR_SIZE);
 
     blk_mig_lock();
     block_mig_state.submitted++;
@@ -556,9 +553,8 @@ static int mig_save_device_dirty(QEMUFile *f, BlkMigDevState *bmds,
             blk->nr_sectors = nr_sectors;
 
             if (is_async) {
-                blk->iov.iov_base = blk->buf;
-                blk->iov.iov_len = nr_sectors * BDRV_SECTOR_SIZE;
-                qemu_iovec_init_external(&blk->qiov, &blk->iov, 1);
+                qemu_iovec_init_buf(&blk->qiov, blk->buf,
+                                    nr_sectors * BDRV_SECTOR_SIZE);
 
                 blk->aiocb = blk_aio_preadv(bmds->blk,
                                             sector * BDRV_SECTOR_SIZE,
-- 
2.18.0

[Qemu-devel] [PATCH v4 14/17] tests/test-bdrv-drain: use QEMU_IOVEC_INIT_BUF

[Vladimir Sementsov-Ogievskiy]

Use new QEMU_IOVEC_INIT_BUF() instead of
qemu_iovec_init_external( ... , 1), which simplifies the code.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 tests/test-bdrv-drain.c | 29 ++++-------------------------
 1 file changed, 4 insertions(+), 25 deletions(-)

diff --git a/tests/test-bdrv-drain.c b/tests/test-bdrv-drain.c
index ee1740ff06..821be405f0 100644
--- a/tests/test-bdrv-drain.c
+++ b/tests/test-bdrv-drain.c
@@ -204,12 +204,7 @@ static void test_drv_cb_common(enum drain_type drain_type, bool recursive)
     BlockAIOCB *acb;
     int aio_ret;
 
-    QEMUIOVector qiov;
-    struct iovec iov = {
-        .iov_base = NULL,
-        .iov_len = 0,
-    };
-    qemu_iovec_init_external(&qiov, &iov, 1);
+    QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, NULL, 0);
 
     blk = blk_new(BLK_PERM_ALL, BLK_PERM_ALL);
     bs = bdrv_new_open_driver(&bdrv_test, "test-node", BDRV_O_RDWR,
@@ -670,12 +665,7 @@ static void test_iothread_common(enum drain_type drain_type, int drain_thread)
     AioContext *ctx_a = iothread_get_aio_context(a);
     AioContext *ctx_b = iothread_get_aio_context(b);
 
-    QEMUIOVector qiov;
-    struct iovec iov = {
-        .iov_base = NULL,
-        .iov_len = 0,
-    };
-    qemu_iovec_init_external(&qiov, &iov, 1);
+    QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, NULL, 0);
 
     /* bdrv_drain_all() may only be called from the main loop thread */
     if (drain_type == BDRV_DRAIN_ALL && drain_thread != 0) {
@@ -1148,13 +1138,7 @@ static void coroutine_fn test_co_delete_by_drain(void *opaque)
     BlockDriverState *bs = blk_bs(blk);
     BDRVTestTopState *tts = bs->opaque;
     void *buffer = g_malloc(65536);
-    QEMUIOVector qiov;
-    struct iovec iov = {
-        .iov_base = buffer,
-        .iov_len  = 65536,
-    };
-
-    qemu_iovec_init_external(&qiov, &iov, 1);
+    QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, buffer, 65536);
 
     /* Pretend some internal write operation from parent to child.
      * Important: We have to read from the child, not from the parent!
@@ -1365,12 +1349,7 @@ static void test_detach_indirect(bool by_parent_cb)
     BdrvChild *child_a, *child_b;
     BlockAIOCB *acb;
 
-    QEMUIOVector qiov;
-    struct iovec iov = {
-        .iov_base = NULL,
-        .iov_len = 0,
-    };
-    qemu_iovec_init_external(&qiov, &iov, 1);
+    QEMUIOVector qiov = QEMU_IOVEC_INIT_BUF(qiov, NULL, 0);
 
     if (!by_parent_cb) {
         detach_by_driver_cb_role = child_file;
-- 
2.18.0

[Qemu-devel] [PATCH v4 15/17] hw/ide: drop iov field from IDEState

[Vladimir Sementsov-Ogievskiy]

@iov is used only to initialize @qiov. Let's use new
qemu_iovec_init_buf() instead, which simplifies the code.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 include/hw/ide/internal.h | 1 -
 hw/ide/atapi.c            | 9 ++++-----
 hw/ide/core.c             | 8 ++------
 3 files changed, 6 insertions(+), 12 deletions(-)

diff --git a/include/hw/ide/internal.h b/include/hw/ide/internal.h
index 880413ddc7..fa99486d7a 100644
--- a/include/hw/ide/internal.h
+++ b/include/hw/ide/internal.h
@@ -405,7 +405,6 @@ struct IDEState {
     int atapi_dma; /* true if dma is requested for the packet cmd */
     BlockAcctCookie acct;
     BlockAIOCB *pio_aiocb;
-    struct iovec iov;
     QEMUIOVector qiov;
     QLIST_HEAD(, IDEBufferedRequest) buffered_requests;
     /* ATA DMA state */
diff --git a/hw/ide/atapi.c b/hw/ide/atapi.c
index 39e473f9c2..4de86555d9 100644
--- a/hw/ide/atapi.c
+++ b/hw/ide/atapi.c
@@ -174,16 +174,15 @@ static void cd_read_sector_cb(void *opaque, int ret)
 
 static int cd_read_sector(IDEState *s)
 {
+    void *buf;
+
     if (s->cd_sector_size != 2048 && s->cd_sector_size != 2352) {
         block_acct_invalid(blk_get_stats(s->blk), BLOCK_ACCT_READ);
         return -EINVAL;
     }
 
-    s->iov.iov_base = (s->cd_sector_size == 2352) ?
-                      s->io_buffer + 16 : s->io_buffer;
-
-    s->iov.iov_len = ATAPI_SECTOR_SIZE;
-    qemu_iovec_init_external(&s->qiov, &s->iov, 1);
+    buf = (s->cd_sector_size == 2352) ? s->io_buffer + 16 : s->io_buffer;
+    qemu_iovec_init_buf(&s->qiov, buf, ATAPI_SECTOR_SIZE);
 
     trace_cd_read_sector(s->lba);
 
diff --git a/hw/ide/core.c b/hw/ide/core.c
index 84832008b8..13f8f78ca6 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -774,9 +774,7 @@ static void ide_sector_read(IDEState *s)
         return;
     }
 
-    s->iov.iov_base = s->io_buffer;
-    s->iov.iov_len  = n * BDRV_SECTOR_SIZE;
-    qemu_iovec_init_external(&s->qiov, &s->iov, 1);
+    qemu_iovec_init_buf(&s->qiov, s->io_buffer, n * BDRV_SECTOR_SIZE);
 
     block_acct_start(blk_get_stats(s->blk), &s->acct,
                      n * BDRV_SECTOR_SIZE, BLOCK_ACCT_READ);
@@ -1045,9 +1043,7 @@ static void ide_sector_write(IDEState *s)
         return;
     }
 
-    s->iov.iov_base = s->io_buffer;
-    s->iov.iov_len  = n * BDRV_SECTOR_SIZE;
-    qemu_iovec_init_external(&s->qiov, &s->iov, 1);
+    qemu_iovec_init_buf(&s->qiov, s->io_buffer, n * BDRV_SECTOR_SIZE);
 
     block_acct_start(blk_get_stats(s->blk), &s->acct,
                      n * BDRV_SECTOR_SIZE, BLOCK_ACCT_WRITE);
-- 
2.18.0

[Qemu-devel] [PATCH v4 16/17] hw/ide: drop iov field from IDEBufferedRequest

[Vladimir Sementsov-Ogievskiy]

@iov is used only to initialize @qiov. Let's use new
qemu_iovec_init_buf() instead, which simplifies the code.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 include/hw/ide/internal.h |  1 -
 hw/ide/core.c             | 11 ++++++-----
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/include/hw/ide/internal.h b/include/hw/ide/internal.h
index fa99486d7a..1b02bb9151 100644
--- a/include/hw/ide/internal.h
+++ b/include/hw/ide/internal.h
@@ -346,7 +346,6 @@ extern const char *IDE_DMA_CMD_lookup[IDE_DMA__COUNT];
 
 typedef struct IDEBufferedRequest {
     QLIST_ENTRY(IDEBufferedRequest) list;
-    struct iovec iov;
     QEMUIOVector qiov;
     QEMUIOVector *original_qiov;
     BlockCompletionFunc *original_cb;
diff --git a/hw/ide/core.c b/hw/ide/core.c
index 13f8f78ca6..6afadf894f 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -629,13 +629,15 @@ static void ide_buffered_readv_cb(void *opaque, int ret)
     IDEBufferedRequest *req = opaque;
     if (!req->orphaned) {
         if (!ret) {
-            qemu_iovec_from_buf(req->original_qiov, 0, req->iov.iov_base,
+            assert(req->qiov.size == req->original_qiov->size);
+            qemu_iovec_from_buf(req->original_qiov, 0,
+                                req->qiov.local_iov.iov_base,
                                 req->original_qiov->size);
         }
         req->original_cb(req->original_opaque, ret);
     }
     QLIST_REMOVE(req, list);
-    qemu_vfree(req->iov.iov_base);
+    qemu_vfree(qemu_iovec_buf(&req->qiov));
     g_free(req);
 }
 
@@ -660,9 +662,8 @@ BlockAIOCB *ide_buffered_readv(IDEState *s, int64_t sector_num,
     req->original_qiov = iov;
     req->original_cb = cb;
     req->original_opaque = opaque;
-    req->iov.iov_base = qemu_blockalign(blk_bs(s->blk), iov->size);
-    req->iov.iov_len = iov->size;
-    qemu_iovec_init_external(&req->qiov, &req->iov, 1);
+    qemu_iovec_init_buf(&req->qiov, blk_blockalign(s->blk, iov->size),
+                        iov->size);
 
     aioreq = blk_aio_preadv(s->blk, sector_num << BDRV_SECTOR_BITS,
                             &req->qiov, 0, ide_buffered_readv_cb, req);
-- 
2.18.0

[Qemu-devel] [PATCH v4 17/17] hw/ide: drop iov field from IDEDMA

[Vladimir Sementsov-Ogievskiy]

@iov is used only to initialize @qiov. Let's use new
qemu_iovec_init_buf() instead, which simplifies the code.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 include/hw/ide/internal.h | 1 -
 hw/ide/atapi.c            | 5 ++---
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/include/hw/ide/internal.h b/include/hw/ide/internal.h
index 1b02bb9151..8efd03132b 100644
--- a/include/hw/ide/internal.h
+++ b/include/hw/ide/internal.h
@@ -455,7 +455,6 @@ struct IDEDMAOps {
 
 struct IDEDMA {
     const struct IDEDMAOps *ops;
-    struct iovec iov;
     QEMUIOVector qiov;
     BlockAIOCB *aiocb;
 };
diff --git a/hw/ide/atapi.c b/hw/ide/atapi.c
index 4de86555d9..1b0f66cc08 100644
--- a/hw/ide/atapi.c
+++ b/hw/ide/atapi.c
@@ -420,9 +420,8 @@ static void ide_atapi_cmd_read_dma_cb(void *opaque, int ret)
         data_offset = 0;
     }
     trace_ide_atapi_cmd_read_dma_cb_aio(s, s->lba, n);
-    s->bus->dma->iov.iov_base = (void *)(s->io_buffer + data_offset);
-    s->bus->dma->iov.iov_len = n * ATAPI_SECTOR_SIZE;
-    qemu_iovec_init_external(&s->bus->dma->qiov, &s->bus->dma->iov, 1);
+    qemu_iovec_init_buf(&s->bus->dma->qiov, s->io_buffer + data_offset,
+                        n * ATAPI_SECTOR_SIZE);
 
     s->bus->dma->aiocb = ide_buffered_readv(s, (int64_t)s->lba << 2,
                                             &s->bus->dma->qiov, n * 4,
-- 
2.18.0

Re: [Qemu-devel] [PATCH v4 00/17] block: local qiov helper

[Stefan Hajnoczi]

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On Mon, Feb 18, 2019 at 05:09:09PM +0300, Vladimir Sementsov-Ogievskiy wrote:
> Hi all!
> 
> Here is a new simple helper for a very often patter
> around qemu_iovec_init_external, when we need simple qiov with only
> one iov, initialized from external buffer.
> 
> v4:
>  01: tiny improvements by Eric
>      + fix bug: s/niov/nalloc in assertion
>      + rename s/qemu_iovec_get_buf/qemu_iovec_buf,
>        to don't look like getter, which in turn should not return
>        pointer to something internal to be freed separately.
>      So, no r-b's in 01 
>  07,10,16
>     - rebase on new function name qemu_iovec_buf 
>     - save r-b's by Eric and Stefan
>  others unchanged, add r-b's by Eric and Stefan
> 
> v3:
>   01-02: tiny improvements, described in patch-emails
>   03-17: new patches
> 
>   Note: only hw/scsi/scsi-disk.c not updated, as it has too tricky
>         logic around @iov fields of structures. So, it is simpler to
>         keep it as is.
> 
> v2 was "[PATCH v2 0/2] block: local qiov helper: part I"
> https://lists.gnu.org/archive/html/qemu-devel/2019-02/msg01610.html
> 
> Vladimir Sementsov-Ogievskiy (17):
>   block: enhance QEMUIOVector structure
>   block/io: use qemu_iovec_init_buf
>   block/block-backend: use QEMU_IOVEC_INIT_BUF
>   block/backup: use qemu_iovec_init_buf
>   block/commit: use QEMU_IOVEC_INIT_BUF
>   block/stream: use QEMU_IOVEC_INIT_BUF
>   block/parallels: use QEMU_IOVEC_INIT_BUF
>   block/qcow: use qemu_iovec_init_buf
>   block/qcow2: use qemu_iovec_init_buf
>   block/qed: use qemu_iovec_init_buf
>   block/vmdk: use qemu_iovec_init_buf
>   qemu-img: use qemu_iovec_init_buf
>   migration/block: use qemu_iovec_init_buf
>   tests/test-bdrv-drain: use QEMU_IOVEC_INIT_BUF
>   hw/ide: drop iov field from IDEState
>   hw/ide: drop iov field from IDEBufferedRequest
>   hw/ide: drop iov field from IDEDMA
> 
>  include/hw/ide/internal.h |  3 --
>  include/qemu/iov.h        | 64 +++++++++++++++++++++++++++-
>  block/backup.c            |  5 +--
>  block/block-backend.c     | 13 +-----
>  block/commit.c            |  7 +--
>  block/io.c                | 89 +++++++++------------------------------
>  block/parallels.c         | 13 +++---
>  block/qcow.c              | 21 ++-------
>  block/qcow2.c             | 12 +-----
>  block/qed-table.c         | 16 ++-----
>  block/qed.c               | 31 ++++----------
>  block/stream.c            |  7 +--
>  block/vmdk.c              |  7 +--
>  hw/ide/atapi.c            | 14 +++---
>  hw/ide/core.c             | 19 ++++-----
>  migration/block.c         | 10 ++---
>  qemu-img.c                | 10 +----
>  tests/test-bdrv-drain.c   | 29 ++-----------
>  18 files changed, 134 insertions(+), 236 deletions(-)
> 
> -- 
> 2.18.0
> 
> 

Thanks, applied to my block tree:
https://github.com/stefanha/qemu/commits/block

Stefan

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