block: add interface to toggle copy-on-read
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 <stefanha@linux.vnet.ibm.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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parent
dbffbdcfff
commit
53fec9d3fd
22
block.c
22
block.c
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@ -538,6 +538,22 @@ int bdrv_parse_cache_flags(const char *mode, int *flags)
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return 0;
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return 0;
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}
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}
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/**
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* The copy-on-read flag is actually a reference count so multiple users may
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* use the feature without worrying about clobbering its previous state.
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* Copy-on-read stays enabled until all users have called to disable it.
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*/
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void bdrv_enable_copy_on_read(BlockDriverState *bs)
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{
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bs->copy_on_read++;
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}
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void bdrv_disable_copy_on_read(BlockDriverState *bs)
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{
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assert(bs->copy_on_read > 0);
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bs->copy_on_read--;
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}
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/*
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/*
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* Common part for opening disk images and files
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* Common part for opening disk images and files
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*/
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*/
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@ -559,6 +575,11 @@ static int bdrv_open_common(BlockDriverState *bs, const char *filename,
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bs->growable = 0;
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bs->growable = 0;
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bs->buffer_alignment = 512;
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bs->buffer_alignment = 512;
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assert(bs->copy_on_read == 0); /* bdrv_new() and bdrv_close() make it so */
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if ((flags & BDRV_O_RDWR) && (flags & BDRV_O_COPY_ON_READ)) {
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bdrv_enable_copy_on_read(bs);
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}
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pstrcpy(bs->filename, sizeof(bs->filename), filename);
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pstrcpy(bs->filename, sizeof(bs->filename), filename);
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bs->backing_file[0] = '\0';
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bs->backing_file[0] = '\0';
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@ -801,6 +822,7 @@ void bdrv_close(BlockDriverState *bs)
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#endif
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#endif
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bs->opaque = NULL;
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bs->opaque = NULL;
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bs->drv = NULL;
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bs->drv = NULL;
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bs->copy_on_read = 0;
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if (bs->file != NULL) {
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if (bs->file != NULL) {
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bdrv_close(bs->file);
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bdrv_close(bs->file);
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4
block.h
4
block.h
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@ -70,6 +70,7 @@ typedef struct BlockDevOps {
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#define BDRV_O_NATIVE_AIO 0x0080 /* use native AIO instead of the thread pool */
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#define BDRV_O_NATIVE_AIO 0x0080 /* use native AIO instead of the thread pool */
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#define BDRV_O_NO_BACKING 0x0100 /* don't open the backing file */
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#define BDRV_O_NO_BACKING 0x0100 /* don't open the backing file */
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#define BDRV_O_NO_FLUSH 0x0200 /* disable flushing on this disk */
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#define BDRV_O_NO_FLUSH 0x0200 /* disable flushing on this disk */
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#define BDRV_O_COPY_ON_READ 0x0400 /* copy read backing sectors into image */
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#define BDRV_O_CACHE_MASK (BDRV_O_NOCACHE | BDRV_O_CACHE_WB | BDRV_O_NO_FLUSH)
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#define BDRV_O_CACHE_MASK (BDRV_O_NOCACHE | BDRV_O_CACHE_WB | BDRV_O_NO_FLUSH)
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@ -312,6 +313,9 @@ void bdrv_reset_dirty(BlockDriverState *bs, int64_t cur_sector,
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int nr_sectors);
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int nr_sectors);
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int64_t bdrv_get_dirty_count(BlockDriverState *bs);
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int64_t bdrv_get_dirty_count(BlockDriverState *bs);
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void bdrv_enable_copy_on_read(BlockDriverState *bs);
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void bdrv_disable_copy_on_read(BlockDriverState *bs);
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void bdrv_set_in_use(BlockDriverState *bs, int in_use);
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void bdrv_set_in_use(BlockDriverState *bs, int in_use);
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int bdrv_in_use(BlockDriverState *bs);
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int bdrv_in_use(BlockDriverState *bs);
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@ -198,6 +198,8 @@ struct BlockDriverState {
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int encrypted; /* if true, the media is encrypted */
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int encrypted; /* if true, the media is encrypted */
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int valid_key; /* if true, a valid encryption key has been set */
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int valid_key; /* if true, a valid encryption key has been set */
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int sg; /* if true, the device is a /dev/sg* */
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int sg; /* if true, the device is a /dev/sg* */
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int copy_on_read; /* if true, copy read backing sectors into image
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note this is a reference count */
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BlockDriver *drv; /* NULL means no media */
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BlockDriver *drv; /* NULL means no media */
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void *opaque;
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void *opaque;
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