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[Qemu-devel] [PATCH v4 4/8] block: add bdrv_set_copy_on_read()
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [PATCH v4 4/8] block: add bdrv_set_copy_on_read() |
Date: |
Wed, 23 Nov 2011 11:47:54 +0000 |
The bdrv_set_copy_on_read() function 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>
---
block.c | 22 ++++++++++++++++++++++
block.h | 3 +++
block_int.h | 2 ++
3 files changed, 27 insertions(+), 0 deletions(-)
diff --git a/block.c b/block.c
index 27c4e84..c90880b 100644
--- a/block.c
+++ b/block.c
@@ -538,6 +538,22 @@ int bdrv_parse_cache_flags(const char *mode, int *flags)
return 0;
}
+/**
+ * Enable/disable copy-on-read
+ *
+ * This is based on a reference count so multiple users may call this function
+ * without worrying about clobbering the previous state. Copy-on-read stays
+ * enabled until all users have called to disable it.
+ */
+void bdrv_set_copy_on_read(BlockDriverState *bs, bool enable)
+{
+ if (enable) {
+ bs->copy_on_read++;
+ } else {
+ 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) {
+ bdrv_set_copy_on_read(bs, !!(flags & BDRV_O_COPY_ON_READ));
+ }
+
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 ad8dd48..68b4b14 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)
@@ -308,6 +309,8 @@ void bdrv_reset_dirty(BlockDriverState *bs, int64_t
cur_sector,
int nr_sectors);
int64_t bdrv_get_dirty_count(BlockDriverState *bs);
+void bdrv_set_copy_on_read(BlockDriverState *bs, bool enable);
+
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 788fde9..3c5bacb 100644
--- a/block_int.h
+++ b/block_int.h
@@ -193,6 +193,8 @@ 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;
--
1.7.7.1
- [Qemu-devel] [PATCH v4 0/8] block: generic copy-on-read, Stefan Hajnoczi, 2011/11/23
- [Qemu-devel] [PATCH v4 8/8] block: add -drive copy-on-read=on|off, Stefan Hajnoczi, 2011/11/23
- [Qemu-devel] [PATCH v4 5/8] block: wait for overlapping requests, Stefan Hajnoczi, 2011/11/23
- [Qemu-devel] [PATCH v4 7/8] block: core copy-on-read logic, Stefan Hajnoczi, 2011/11/23
- [Qemu-devel] [PATCH v4 6/8] block: request overlap detection, Stefan Hajnoczi, 2011/11/23
- [Qemu-devel] [PATCH v4 1/8] qemu-common: add QEMU_ALIGN_DOWN() and QEMU_ALIGN_UP() macros, Stefan Hajnoczi, 2011/11/23
- [Qemu-devel] [PATCH v4 4/8] block: add bdrv_set_copy_on_read(),
Stefan Hajnoczi <=
- [Qemu-devel] [PATCH v4 3/8] block: add request tracking, Stefan Hajnoczi, 2011/11/23
- [Qemu-devel] [PATCH v4 2/8] coroutine: add qemu_co_queue_restart_all(), Stefan Hajnoczi, 2011/11/23