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[Qemu-devel] [PATCH 09/13] block: add bdrv_aio_copy_backing()
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [PATCH 09/13] block: add bdrv_aio_copy_backing() |
Date: |
Tue, 14 Jun 2011 19:18:27 +0100 |
From: Anthony Liguori <address@hidden>
Add the bdrv_aio_copy_backing() function to the BlockDriver interface.
This function copies unallocated sectors from the backing file and can
be used to implement image streaming.
Signed-off-by: Anthony Liguori <address@hidden>
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
block.c | 37 +++++++++++++++++++++++++++++++++++++
block.h | 5 +++++
block_int.h | 2 ++
3 files changed, 44 insertions(+), 0 deletions(-)
diff --git a/block.c b/block.c
index 99068c9..4da35be 100644
--- a/block.c
+++ b/block.c
@@ -2221,6 +2221,43 @@ BlockDriverAIOCB *bdrv_aio_writev(BlockDriverState *bs,
int64_t sector_num,
return ret;
}
+/**
+ * Attempt to copy unallocated sectors from backing file.
+ *
+ * @sector_num - the first sector to start from
+ * @cb - completion callback
+ * @opaque - data to pass completion callback
+ *
+ * Returns NULL if the image format not support the operation, the image is
+ * read-only, or no image is open.
+ *
+ * The intention of this function is for a user to execute it once with a
+ * sector_num of 0 and then upon receiving a completion callback, to remember
+ * the number of sectors copied, and then to call this function again with
+ * an offset adjusted by the number of sectors previously copied.
+ *
+ * This allows a user to progressive stream in an image at a pace that makes
+ * sense. In general, this function tries to do the smallest amount of I/O
+ * possible to do some useful work.
+ *
+ * This function only really makes sense in combination with a block format
+ * that supports copy on read and has it enabled. If copy on read is not
+ * enabled, a block format driver may return NULL.
+ *
+ * If an I/O error occurs the completion callback is invoked with -errno in the
+ * nb_sectors argument.
+ */
+BlockDriverAIOCB *bdrv_aio_copy_backing(BlockDriverState *bs,
+ int64_t sector_num,
+ BlockDriverCopyBackingCB *cb,
+ void *opaque)
+{
+ if (!bs->drv || bs->read_only || !bs->drv->bdrv_aio_copy_backing) {
+ return NULL;
+ }
+
+ return bs->drv->bdrv_aio_copy_backing(bs, sector_num, cb, opaque);
+}
typedef struct MultiwriteCB {
int error;
diff --git a/block.h b/block.h
index deb19ec..b5de366 100644
--- a/block.h
+++ b/block.h
@@ -112,6 +112,7 @@ typedef struct BlockDriverAIOCB BlockDriverAIOCB;
typedef void BlockDriverCompletionFunc(void *opaque, int ret);
typedef void BlockDriverDirtyHandler(BlockDriverState *bs, int64_t sector,
int sector_num);
+typedef void BlockDriverCopyBackingCB(void *opaque, int nb_sectors);
BlockDriverAIOCB *bdrv_aio_readv(BlockDriverState *bs, int64_t sector_num,
QEMUIOVector *iov, int nb_sectors,
BlockDriverCompletionFunc *cb, void *opaque);
@@ -120,6 +121,10 @@ BlockDriverAIOCB *bdrv_aio_writev(BlockDriverState *bs,
int64_t sector_num,
BlockDriverCompletionFunc *cb, void *opaque);
BlockDriverAIOCB *bdrv_aio_flush(BlockDriverState *bs,
BlockDriverCompletionFunc *cb, void *opaque);
+BlockDriverAIOCB *bdrv_aio_copy_backing(BlockDriverState *bs,
+ int64_t sector_num,
+ BlockDriverCopyBackingCB *cb,
+ void *opaque);
void bdrv_aio_cancel(BlockDriverAIOCB *acb);
typedef struct BlockRequest {
diff --git a/block_int.h b/block_int.h
index 135625a..327efb3 100644
--- a/block_int.h
+++ b/block_int.h
@@ -73,6 +73,8 @@ struct BlockDriver {
BlockDriverCompletionFunc *cb, void *opaque);
BlockDriverAIOCB *(*bdrv_aio_flush)(BlockDriverState *bs,
BlockDriverCompletionFunc *cb, void *opaque);
+ BlockDriverAIOCB *(*bdrv_aio_copy_backing)(BlockDriverState *bs,
+ int64_t sector_num, BlockDriverCopyBackingCB *cb, void *opaque);
int (*bdrv_discard)(BlockDriverState *bs, int64_t sector_num,
int nb_sectors);
--
1.7.5.3
- [Qemu-devel] [PATCH 00/13] QED image streaming, Stefan Hajnoczi, 2011/06/14
- [Qemu-devel] [PATCH 06/13] qed: add support for copy-on-read, Stefan Hajnoczi, 2011/06/14
- [Qemu-devel] [PATCH 07/13] qed: avoid deadlock on emulated synchronous I/O, Stefan Hajnoczi, 2011/06/14
- [Qemu-devel] [PATCH 09/13] block: add bdrv_aio_copy_backing(),
Stefan Hajnoczi <=
- [Qemu-devel] [PATCH 04/13] qed: extract qed_start_allocating_write(), Stefan Hajnoczi, 2011/06/14
- [Qemu-devel] [PATCH 13/13] trace: trace bdrv_aio_readv/writev error paths, Stefan Hajnoczi, 2011/06/14
- [Qemu-devel] [PATCH 05/13] qed: make qed_aio_write_alloc() reusable, Stefan Hajnoczi, 2011/06/14
- [Qemu-devel] [PATCH 12/13] qed: intelligent streaming implementation, Stefan Hajnoczi, 2011/06/14
- [Qemu-devel] [PATCH 08/13] qerror: add qerror_from_args() to create qerror objects, Stefan Hajnoczi, 2011/06/14
- [Qemu-devel] [PATCH 10/13] qmp: add QMP support for stream commands, Stefan Hajnoczi, 2011/06/14
- [Qemu-devel] [PATCH 11/13] block: add -drive stream=on|off, Stefan Hajnoczi, 2011/06/14
- [Qemu-devel] [PATCH 03/13] qed: replace is_write with flags field, Stefan Hajnoczi, 2011/06/14
- [Qemu-devel] [PATCH 01/13] qemu-config: }, { -> }, { to please checkpatch.pl, Stefan Hajnoczi, 2011/06/14
- [Qemu-devel] [PATCH 02/13] block: add -drive copy-on-read=on|off, Stefan Hajnoczi, 2011/06/14