From d5b3c858d7d2d96cf89495c95c2f07eb246b6730 Mon Sep 17 00:00:00 2001

From: Kevin Wolf <kwolf@redhat.com>

Date: Mon, 2 Dec 2013 15:07:48 +0100

Subject: [PATCH 11/37] block: Introduce bdrv_aligned_preadv()

Message-id: <1392117622-28812-12-git-send-email-kwolf@redhat.com>

Patchwork-id: 57176

O-Subject: [RHEL-7.0 qemu-kvm PATCH v2 11/37] block: Introduce bdrv_aligned_preadv()

Bugzilla: 748906

RH-Acked-by: Laszlo Ersek <lersek@redhat.com>

RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

RH-Acked-by: Max Reitz <mreitz@redhat.com>

This separates the part of bdrv_co_do_readv() that needs to happen

before the request is modified to match the backend alignment, and a

part that needs to be executed afterwards and passes the request to the

BlockDriver.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>

Reviewed-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>

Reviewed-by: Max Reitz <mreitz@redhat.com>

(cherry picked from commit d0c7f642f5eb2cb21d0c3acf766cb375eaaf4666)

Conflicts:

	block.c

Conflicts because RHEL 7 still has the old I/O throttling code.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>

---

 block.c | 59 ++++++++++++++++++++++++++++++++++++++++++-----------------

 1 file changed, 42 insertions(+), 17 deletions(-)

---

 block.c |   59 ++++++++++++++++++++++++++++++++++++++++++-----------------

 1 files changed, 42 insertions(+), 17 deletions(-)

diff --git a/block.c b/block.c

index 40a4a34..1787ab0 100644

--- a/block.c

+++ b/block.c

@@ -2723,31 +2723,24 @@ err:

 }

 /*

- * Handle a read request in coroutine context

+ * Forwards an already correctly aligned request to the BlockDriver. This

+ * handles copy on read and zeroing after EOF; any other features must be

+ * implemented by the caller.

  */

-static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs,

-    int64_t sector_num, int nb_sectors, QEMUIOVector *qiov,

-    BdrvRequestFlags flags)

+static int coroutine_fn bdrv_aligned_preadv(BlockDriverState *bs,

+    int64_t offset, unsigned int bytes, QEMUIOVector *qiov, int flags)

 {

     BlockDriver *drv = bs->drv;

     BdrvTrackedRequest req;

     int ret;

-    if (!drv) {

-        return -ENOMEDIUM;

-    }

-    if (bdrv_check_request(bs, sector_num, nb_sectors)) {

-        return -EIO;

-    }

+    int64_t sector_num = offset >> BDRV_SECTOR_BITS;

+    unsigned int nb_sectors = bytes >> BDRV_SECTOR_BITS;

-    /* throttling disk read I/O */

-    if (bs->io_limits_enabled) {

-        bdrv_io_limits_intercept(bs, false, nb_sectors);

-    }

+    assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);

+    assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);

-    if (bs->copy_on_read) {

-        flags |= BDRV_REQ_COPY_ON_READ;

-    }

+    /* Handle Copy on Read and associated serialisation */

     if (flags & BDRV_REQ_COPY_ON_READ) {

         bs->copy_on_read_in_flight++;

     }

@@ -2772,6 +2765,7 @@ static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs,

         }

     }

+    /* Forward the request to the BlockDriver */

     if (!(bs->zero_beyond_eof && bs->growable)) {

         ret = drv->bdrv_co_readv(bs, sector_num, nb_sectors, qiov);

     } else {

@@ -2812,6 +2806,37 @@ out:

     return ret;

 }

+/*

+ * 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,

+    BdrvRequestFlags flags)

+{

+    BlockDriver *drv = bs->drv;

+    int ret;

+

+    if (!drv) {

+        return -ENOMEDIUM;

+    }

+    if (bdrv_check_request(bs, sector_num, nb_sectors)) {

+        return -EIO;

+    }

+

+    if (bs->copy_on_read) {

+        flags |= BDRV_REQ_COPY_ON_READ;

+    }

+

+    /* throttling disk I/O */

+    if (bs->io_limits_enabled) {

+        bdrv_io_limits_intercept(bs, false, nb_sectors);

+    }

+

+    ret = bdrv_aligned_preadv(bs, sector_num << BDRV_SECTOR_BITS,

+                             nb_sectors << BDRV_SECTOR_BITS, qiov, flags);

+    return ret;

+}

+

 int coroutine_fn bdrv_co_readv(BlockDriverState *bs, int64_t sector_num,

     int nb_sectors, QEMUIOVector *qiov)

 {

-- 

1.7.1