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[Qemu-devel] [PATCH 32/41] block: add interface to toggle copy-on-read
From: |
Kevin Wolf |
Subject: |
[Qemu-devel] [PATCH 32/41] block: add interface to toggle copy-on-read |
Date: |
Mon, 5 Dec 2011 15:21:09 +0100 |
From: Stefan Hajnoczi <address@hidden>
The bdrv_enable_copy_on_read()/bdrv_disable_copy_on_read() functions can
be used to programmatically enable or disable copy-on-read for a block
device. Later patches add the actual copy-on-read logic.
Signed-off-by: Stefan Hajnoczi <address@hidden>
Signed-off-by: Kevin Wolf <address@hidden>
---
block.c | 22 ++++++++++++++++++++++
block.h | 4 ++++
block_int.h | 2 ++
3 files changed, 28 insertions(+), 0 deletions(-)
diff --git a/block.c b/block.c
index 1643667..9b3cb75 100644
--- a/block.c
+++ b/block.c
@@ -538,6 +538,22 @@ int bdrv_parse_cache_flags(const char *mode, int *flags)
return 0;
}
+/**
+ * The copy-on-read flag is actually a reference count so multiple users may
+ * use the feature without worrying about clobbering its previous state.
+ * Copy-on-read stays enabled until all users have called to disable it.
+ */
+void bdrv_enable_copy_on_read(BlockDriverState *bs)
+{
+ bs->copy_on_read++;
+}
+
+void bdrv_disable_copy_on_read(BlockDriverState *bs)
+{
+ assert(bs->copy_on_read > 0);
+ bs->copy_on_read--;
+}
+
/*
* Common part for opening disk images and files
*/
@@ -559,6 +575,11 @@ static int bdrv_open_common(BlockDriverState *bs, const
char *filename,
bs->growable = 0;
bs->buffer_alignment = 512;
+ assert(bs->copy_on_read == 0); /* bdrv_new() and bdrv_close() make it so */
+ if ((flags & BDRV_O_RDWR) && (flags & BDRV_O_COPY_ON_READ)) {
+ bdrv_enable_copy_on_read(bs);
+ }
+
pstrcpy(bs->filename, sizeof(bs->filename), filename);
bs->backing_file[0] = '\0';
@@ -801,6 +822,7 @@ void bdrv_close(BlockDriverState *bs)
#endif
bs->opaque = NULL;
bs->drv = NULL;
+ bs->copy_on_read = 0;
if (bs->file != NULL) {
bdrv_close(bs->file);
diff --git a/block.h b/block.h
index 8482dbc..5f8a98a 100644
--- a/block.h
+++ b/block.h
@@ -70,6 +70,7 @@ typedef struct BlockDevOps {
#define BDRV_O_NATIVE_AIO 0x0080 /* use native AIO instead of the thread pool
*/
#define BDRV_O_NO_BACKING 0x0100 /* don't open the backing file */
#define BDRV_O_NO_FLUSH 0x0200 /* disable flushing on this disk */
+#define BDRV_O_COPY_ON_READ 0x0400 /* copy read backing sectors into image */
#define BDRV_O_CACHE_MASK (BDRV_O_NOCACHE | BDRV_O_CACHE_WB | BDRV_O_NO_FLUSH)
@@ -312,6 +313,9 @@ void bdrv_reset_dirty(BlockDriverState *bs, int64_t
cur_sector,
int nr_sectors);
int64_t bdrv_get_dirty_count(BlockDriverState *bs);
+void bdrv_enable_copy_on_read(BlockDriverState *bs);
+void bdrv_disable_copy_on_read(BlockDriverState *bs);
+
void bdrv_set_in_use(BlockDriverState *bs, int in_use);
int bdrv_in_use(BlockDriverState *bs);
diff --git a/block_int.h b/block_int.h
index ea818e4..311bd2a 100644
--- a/block_int.h
+++ b/block_int.h
@@ -198,6 +198,8 @@ struct BlockDriverState {
int encrypted; /* if true, the media is encrypted */
int valid_key; /* if true, a valid encryption key has been set */
int sg; /* if true, the device is a /dev/sg* */
+ int copy_on_read; /* if true, copy read backing sectors into image
+ note this is a reference count */
BlockDriver *drv; /* NULL means no media */
void *opaque;
--
1.7.6.4
- [Qemu-devel] [PATCH 27/41] block: drop .bdrv_is_allocated() interface, (continued)
- [Qemu-devel] [PATCH 27/41] block: drop .bdrv_is_allocated() interface, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 24/41] vvfat: convert to .bdrv_co_is_allocated(), Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 20/41] block: use public bdrv_is_allocated() interface, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 23/41] block: convert qcow2, qcow2, and vmdk to .bdrv_co_is_allocated(), Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 21/41] block: add .bdrv_co_is_allocated(), Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 25/41] vdi: convert to .bdrv_co_is_allocated(), Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 29/41] qemu-common: add QEMU_ALIGN_DOWN() and QEMU_ALIGN_UP() macros, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 31/41] block: add request tracking, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 30/41] coroutine: add qemu_co_queue_restart_all(), Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 28/41] block: add bdrv_co_is_allocated() interface, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 32/41] block: add interface to toggle copy-on-read,
Kevin Wolf <=
- [Qemu-devel] [PATCH 39/41] block: implement bdrv_co_is_allocated() boundary cases, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 37/41] cow: use bdrv_co_is_allocated(), Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 35/41] block: core copy-on-read logic, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 36/41] block: add -drive copy-on-read=on|off, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 34/41] block: request overlap detection, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 40/41] block: wait_for_overlapping_requests() deadlock detection, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 41/41] block: convert qemu_aio_flush() calls to bdrv_drain_all(), Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 33/41] block: wait for overlapping requests, Kevin Wolf, 2011/12/05
- [Qemu-devel] [PATCH 38/41] dma-helpers: Add trace events, Kevin Wolf, 2011/12/05