diff options
| -rw-r--r-- | block.c | 22 | ||||
| -rw-r--r-- | block.h | 4 | ||||
| -rw-r--r-- | block_int.h | 2 |
3 files changed, 28 insertions, 0 deletions
@@ -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); @@ -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; |