Re: [Qemu-devel] [PATCH v3 10/29] block: Introduce bdrv_co_do_preadv()

[Benoît Canet]

Le Friday 17 Jan 2014 à 15:15:00 (+0100), Kevin Wolf a écrit :
 Similar to bdrv_pread(), which aligns byte-aligned request to 512 byte
 sectors, bdrv_co_do_preadv() takes a byte-aligned request and aligns it
 to the alignment specified in bs-request_alignment.
 
 Signed-off-by: Kevin Wolf kw...@redhat.com
 ---
  block.c | 64 ++--
  1 file changed, 58 insertions(+), 6 deletions(-)
 
 diff --git a/block.c b/block.c
 index 0c2baf5..f378a10 100644
 --- a/block.c
 +++ b/block.c
 @@ -2791,17 +2791,23 @@ out:
  /*
   * Handle a read request in coroutine context
   */
 -static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs,
 -int64_t sector_num, int nb_sectors, QEMUIOVector *qiov,
 +static int coroutine_fn bdrv_co_do_preadv(BlockDriverState *bs,
 +int64_t offset, unsigned int bytes, QEMUIOVector *qiov,
  BdrvRequestFlags flags)
  {
  BlockDriver *drv = bs-drv;
 +/* TODO Lift BDRV_SECTOR_SIZE restriction in BlockDriver interface */
 +uint64_t align = MAX(BDRV_SECTOR_SIZE, bs-request_alignment);
 +uint8_t *head_buf = NULL;
 +uint8_t *tail_buf = NULL;
 +QEMUIOVector local_qiov;
 +bool use_local_qiov = false;
  int ret;
  
  if (!drv) {
  return -ENOMEDIUM;
  }
 -if (bdrv_check_request(bs, sector_num, nb_sectors)) {
 +if (bdrv_check_byte_request(bs, offset, bytes)) {
  return -EIO;
  }
  
 @@ -2811,14 +2817,60 @@ static int coroutine_fn 
 bdrv_co_do_readv(BlockDriverState *bs,
  
  /* throttling disk I/O */
  if (bs-io_limits_enabled) {
 -bdrv_io_limits_intercept(bs, nb_sectors, false);
 +/* TODO Switch to byte granularity */
 +bdrv_io_limits_intercept(bs, bytes  BDRV_SECTOR_BITS, false);
 +}
 +
 +/* Align read if necessary by padding qiov */
 +if (offset  (align - 1)) {
 +head_buf = qemu_blockalign(bs, align);
 +qemu_iovec_init(local_qiov, qiov-niov + 2);
 +qemu_iovec_add(local_qiov, head_buf, offset  (align - 1));
 +qemu_iovec_concat(local_qiov, qiov, 0, qiov-size);
 +use_local_qiov = true;
 +
 +bytes += offset  (align - 1);
 +offset = offset  ~(align - 1);
 +}
 +
 +if ((offset + bytes)  (align - 1)) {
 +if (!use_local_qiov) {
 +qemu_iovec_init(local_qiov, qiov-niov + 1);
 +qemu_iovec_concat(local_qiov, qiov, 0, qiov-size);
 +use_local_qiov = true;
 +}
 +tail_buf = qemu_blockalign(bs, align);
 +qemu_iovec_add(local_qiov, tail_buf,
 +   align - ((offset + bytes)  (align - 1)));
 +
 +bytes = ROUND_UP(bytes, align);
 +}
 +
 +ret = bdrv_aligned_preadv(bs, offset, bytes,
 +  use_local_qiov ? local_qiov : qiov,
 +  flags);
 +
 +if (use_local_qiov) {
 +qemu_iovec_destroy(local_qiov);
 +qemu_vfree(head_buf);
 +qemu_vfree(tail_buf);
  }
  
 -ret = bdrv_aligned_preadv(bs, sector_num  BDRV_SECTOR_BITS,
 - nb_sectors  BDRV_SECTOR_BITS, qiov, flags);
  return ret;
  }
  
 +static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs,
 +int64_t sector_num, int nb_sectors, QEMUIOVector *qiov,
 +BdrvRequestFlags flags)
 +{
 +if (nb_sectors  0 || nb_sectors  (UINT_MAX  BDRV_SECTOR_BITS)) {
 +return -EINVAL;
 +}
 +
 +return bdrv_co_do_preadv(bs, sector_num  BDRV_SECTOR_BITS,
 + nb_sectors  BDRV_SECTOR_BITS, qiov, flags);
 +}
 +
  int coroutine_fn bdrv_co_readv(BlockDriverState *bs, int64_t sector_num,
  int nb_sectors, QEMUIOVector *qiov)
  {
 -- 
 1.8.1.4
 
 

Reviewed-by: Benoit Canet ben...@irqsave.net

[Qemu-devel] [PATCH v3 10/29] block: Introduce bdrv_co_do_preadv()

[Kevin Wolf]

Similar to bdrv_pread(), which aligns byte-aligned request to 512 byte
sectors, bdrv_co_do_preadv() takes a byte-aligned request and aligns it
to the alignment specified in bs-request_alignment.

Signed-off-by: Kevin Wolf kw...@redhat.com
---
 block.c | 64 ++--
 1 file changed, 58 insertions(+), 6 deletions(-)

diff --git a/block.c b/block.c
index 0c2baf5..f378a10 100644
--- a/block.c
+++ b/block.c
@@ -2791,17 +2791,23 @@ out:
 /*
  * Handle a read request in coroutine context
  */
-static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs,
-int64_t sector_num, int nb_sectors, QEMUIOVector *qiov,
+static int coroutine_fn bdrv_co_do_preadv(BlockDriverState *bs,
+int64_t offset, unsigned int bytes, QEMUIOVector *qiov,
 BdrvRequestFlags flags)
 {
 BlockDriver *drv = bs-drv;
+/* TODO Lift BDRV_SECTOR_SIZE restriction in BlockDriver interface */
+uint64_t align = MAX(BDRV_SECTOR_SIZE, bs-request_alignment);
+uint8_t *head_buf = NULL;
+uint8_t *tail_buf = NULL;
+QEMUIOVector local_qiov;
+bool use_local_qiov = false;
 int ret;
 
 if (!drv) {
 return -ENOMEDIUM;
 }
-if (bdrv_check_request(bs, sector_num, nb_sectors)) {
+if (bdrv_check_byte_request(bs, offset, bytes)) {
 return -EIO;
 }
 
@@ -2811,14 +2817,60 @@ static int coroutine_fn 
bdrv_co_do_readv(BlockDriverState *bs,
 
 /* throttling disk I/O */
 if (bs-io_limits_enabled) {
-bdrv_io_limits_intercept(bs, nb_sectors, false);
+/* TODO Switch to byte granularity */
+bdrv_io_limits_intercept(bs, bytes  BDRV_SECTOR_BITS, false);
+}
+
+/* Align read if necessary by padding qiov */
+if (offset  (align - 1)) {
+head_buf = qemu_blockalign(bs, align);
+qemu_iovec_init(local_qiov, qiov-niov + 2);
+qemu_iovec_add(local_qiov, head_buf, offset  (align - 1));
+qemu_iovec_concat(local_qiov, qiov, 0, qiov-size);
+use_local_qiov = true;
+
+bytes += offset  (align - 1);
+offset = offset  ~(align - 1);
+}
+
+if ((offset + bytes)  (align - 1)) {
+if (!use_local_qiov) {
+qemu_iovec_init(local_qiov, qiov-niov + 1);
+qemu_iovec_concat(local_qiov, qiov, 0, qiov-size);
+use_local_qiov = true;
+}
+tail_buf = qemu_blockalign(bs, align);
+qemu_iovec_add(local_qiov, tail_buf,
+   align - ((offset + bytes)  (align - 1)));
+
+bytes = ROUND_UP(bytes, align);
+}
+
+ret = bdrv_aligned_preadv(bs, offset, bytes,
+  use_local_qiov ? local_qiov : qiov,
+  flags);
+
+if (use_local_qiov) {
+qemu_iovec_destroy(local_qiov);
+qemu_vfree(head_buf);
+qemu_vfree(tail_buf);
 }
 
-ret = bdrv_aligned_preadv(bs, sector_num  BDRV_SECTOR_BITS,
- nb_sectors  BDRV_SECTOR_BITS, qiov, flags);
 return ret;
 }
 
+static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs,
+int64_t sector_num, int nb_sectors, QEMUIOVector *qiov,
+BdrvRequestFlags flags)
+{
+if (nb_sectors  0 || nb_sectors  (UINT_MAX  BDRV_SECTOR_BITS)) {
+return -EINVAL;
+}
+
+return bdrv_co_do_preadv(bs, sector_num  BDRV_SECTOR_BITS,
+ nb_sectors  BDRV_SECTOR_BITS, qiov, flags);
+}
+
 int coroutine_fn bdrv_co_readv(BlockDriverState *bs, int64_t sector_num,
 int nb_sectors, QEMUIOVector *qiov)
 {
-- 
1.8.1.4

Re: [Qemu-devel] [PATCH v3 10/29] block: Introduce bdrv_co_do_preadv()

[Max Reitz]

On 17.01.2014 15:15, Kevin Wolf wrote:

Similar to bdrv_pread(), which aligns byte-aligned request to 512 byte
sectors, bdrv_co_do_preadv() takes a byte-aligned request and aligns it
to the alignment specified in bs-request_alignment.

Signed-off-by: Kevin Wolf kw...@redhat.com
---
  block.c | 64 ++--
  1 file changed, 58 insertions(+), 6 deletions(-)


Together with patch 29:

Reviewed-by: Max Reitz mre...@redhat.com