[Qemu-devel] [PATCH 6/8] block: take lock around bdrv_write implementations

[Paolo Bonzini <pbonzini@redhat.com>]

This does the first part of the conversion to coroutines, by
wrapping bdrv_write implementations to take the write side of the
rwlock.

Drivers that implement bdrv_write rather than bdrv_co_writev can
then benefit from asynchronous operation (at least if the underlying
protocol supports it, which is not the case for raw-win32), even
though they still operate with a bounce buffer.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 block/cow.c   |   13 ++++++++++++-
 block/nbd.c   |   13 ++++++++++++-
 block/vmdk.c  |   13 ++++++++++++-
 block/vpc.c   |   13 ++++++++++++-
 block/vvfat.c |   13 ++++++++++++-
 5 files changed, 60 insertions(+), 5 deletions(-)

diff --git a/block/cow.c b/block/cow.c
index 9571549..61eaca2 100644
--- a/block/cow.c
+++ b/block/cow.c
@@ -226,6 +226,17 @@ static int cow_write(BlockDriverState *bs, int64_t sector_num,
     return cow_update_bitmap(bs, sector_num, nb_sectors);
 }
 
+static coroutine_fn int cow_co_write(BlockDriverState *bs, int64_t sector_num,
+                                     const uint8_t *buf, int nb_sectors)
+{
+    int ret;
+    BDRVCowState *s = bs->opaque;
+    qemu_co_rwlock_wrlock(&s->lock);
+    ret = cow_write(bs, sector_num, buf, nb_sectors);
+    qemu_co_rwlock_unlock(&s->lock);
+    return ret;
+}
+
 static void cow_close(BlockDriverState *bs)
 {
 }
@@ -320,7 +331,7 @@ static BlockDriver bdrv_cow = {
     .bdrv_probe		= cow_probe,
     .bdrv_open		= cow_open,
     .bdrv_read		= cow_co_read,
-    .bdrv_write		= cow_write,
+    .bdrv_write		= cow_co_write,
     .bdrv_close		= cow_close,
     .bdrv_create	= cow_create,
     .bdrv_flush		= cow_flush,
diff --git a/block/nbd.c b/block/nbd.c
index f8fed92..12da988 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -251,6 +251,17 @@ static coroutine_fn int nbd_co_read(BlockDriverState *bs, int64_t sector_num,
     return ret;
 }
 
+static coroutine_fn int nbd_co_write(BlockDriverState *bs, int64_t sector_num,
+                                     const uint8_t *buf, int nb_sectors)
+{
+    int ret;
+    BDRVNBDState *s = bs->opaque;
+    qemu_co_rwlock_wrlock(&s->lock);
+    ret = nbd_write(bs, sector_num, buf, nb_sectors);
+    qemu_co_rwlock_unlock(&s->lock);
+    return ret;
+}
+
 static void nbd_close(BlockDriverState *bs)
 {
     BDRVNBDState *s = bs->opaque;
@@ -272,7 +283,7 @@ static BlockDriver bdrv_nbd = {
     .instance_size	= sizeof(BDRVNBDState),
     .bdrv_file_open	= nbd_open,
     .bdrv_read		= nbd_co_read,
-    .bdrv_write		= nbd_write,
+    .bdrv_write		= nbd_co_write,
     .bdrv_close		= nbd_close,
     .bdrv_getlength	= nbd_getlength,
     .protocol_name	= "nbd",
diff --git a/block/vmdk.c b/block/vmdk.c
index ff78e25..a0c22f1 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -1114,6 +1114,17 @@ static int vmdk_write(BlockDriverState *bs, int64_t sector_num,
     return 0;
 }
 
+static coroutine_fn int vmdk_co_write(BlockDriverState *bs, int64_t sector_num,
+                                      const uint8_t *buf, int nb_sectors)
+{
+    int ret;
+    BDRVVmdkState *s = bs->opaque;
+    qemu_co_rwlock_wrlock(&s->lock);
+    ret = vmdk_write(bs, sector_num, buf, nb_sectors);
+    qemu_co_rwlock_unlock(&s->lock);
+    return ret;
+}
+
 
 static int vmdk_create_extent(const char *filename, int64_t filesize,
                               bool flat, bool compress)
@@ -1552,7 +1563,7 @@ static BlockDriver bdrv_vmdk = {
     .bdrv_probe     = vmdk_probe,
     .bdrv_open      = vmdk_open,
     .bdrv_read      = vmdk_co_read,
-    .bdrv_write     = vmdk_write,
+    .bdrv_write     = vmdk_co_write,
     .bdrv_close     = vmdk_close,
     .bdrv_create    = vmdk_create,
     .bdrv_flush     = vmdk_flush,
diff --git a/block/vpc.c b/block/vpc.c
index e805769..915e30c 100644
--- a/block/vpc.c
+++ b/block/vpc.c
@@ -456,6 +456,17 @@ static int vpc_write(BlockDriverState *bs, int64_t sector_num,
     return 0;
 }
 
+static coroutine_fn int vpc_co_write(BlockDriverState *bs, int64_t sector_num,
+                                     const uint8_t *buf, int nb_sectors)
+{
+    int ret;
+    BDRVVPCState *s = bs->opaque;
+    qemu_co_rwlock_wrlock(&s->lock);
+    ret = vpc_write(bs, sector_num, buf, nb_sectors);
+    qemu_co_rwlock_unlock(&s->lock);
+    return ret;
+}
+
 static int vpc_flush(BlockDriverState *bs)
 {
     return bdrv_flush(bs->file);
@@ -661,7 +672,7 @@ static BlockDriver bdrv_vpc = {
     .bdrv_probe     = vpc_probe,
     .bdrv_open      = vpc_open,
     .bdrv_read      = vpc_co_read,
-    .bdrv_write     = vpc_write,
+    .bdrv_write     = vpc_co_write,
     .bdrv_flush     = vpc_flush,
     .bdrv_close     = vpc_close,
     .bdrv_create    = vpc_create,
diff --git a/block/vvfat.c b/block/vvfat.c
index f1d94ad..be8f990 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -2725,6 +2725,17 @@ DLOG(checkpoint());
     return 0;
 }
 
+static coroutine_fn int vvfat_co_write(BlockDriverState *bs, int64_t sector_num,
+                                       const uint8_t *buf, int nb_sectors)
+{
+    int ret;
+    BDRVVVFATState *s = bs->opaque;
+    qemu_co_rwlock_wrlock(&s->lock);
+    ret = vvfat_write(bs, sector_num, buf, nb_sectors);
+    qemu_co_rwlock_unlock(&s->lock);
+    return ret;
+}
+
 static int vvfat_is_allocated(BlockDriverState *bs,
 	int64_t sector_num, int nb_sectors, int* n)
 {
@@ -2815,7 +2826,7 @@ static BlockDriver bdrv_vvfat = {
     .instance_size	= sizeof(BDRVVVFATState),
     .bdrv_file_open	= vvfat_open,
     .bdrv_read		= vvfat_co_read,
-    .bdrv_write		= vvfat_write,
+    .bdrv_write		= vvfat_co_write,
     .bdrv_close		= vvfat_close,
     .bdrv_is_allocated	= vvfat_is_allocated,
     .protocol_name	= "fat",
-- 
1.7.6