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block: add discard support 

Add a new bdrv_discard method to free blocks in a mapping image, and a new
drive property to set the granularity for these discard.  If no discard
granularity support is set discard support is disabled.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Christoph Hellwig 2010-12-16 19:36:31 +01:00 committed by Kevin Wolf
parent 61d9d6b091
commit bb8bf76fb1
4 changed files with 24 additions and 1 deletions
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11
block.c
View File

@ -1515,6 +1515,17 @@ int bdrv_has_zero_init(BlockDriverState *bs)
return 1;
}
int bdrv_discard(BlockDriverState *bs, int64_t sector_num, int nb_sectors)
{
if (!bs->drv) {
return -ENOMEDIUM;
}
if (!bs->drv->bdrv_discard) {
return 0;
}
return bs->drv->bdrv_discard(bs, sector_num, nb_sectors);
}
/*
* Returns true iff the specified sector is present in the disk image. Drivers
* not implementing the functionality are assumed to not support backing files,

1
block.h
View File

@ -146,6 +146,7 @@ int bdrv_flush(BlockDriverState *bs);
void bdrv_flush_all(void);
void bdrv_close_all(void);
int bdrv_discard(BlockDriverState *bs, int64_t sector_num, int nb_sectors);
int bdrv_has_zero_init(BlockDriverState *bs);
int bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num, int nb_sectors,
int *pnum);

6
block/raw.c
View File

@ -65,6 +65,11 @@ static int raw_probe(const uint8_t *buf, int buf_size, const char *filename)
return 1; /* everything can be opened as raw image */
}
static int raw_discard(BlockDriverState *bs, int64_t sector_num, int nb_sectors)
{
return bdrv_discard(bs->file, sector_num, nb_sectors);
}
static int raw_is_inserted(BlockDriverState *bs)
{
return bdrv_is_inserted(bs->file);
@ -130,6 +135,7 @@ static BlockDriver bdrv_raw = {
.bdrv_aio_readv = raw_aio_readv,
.bdrv_aio_writev = raw_aio_writev,
.bdrv_aio_flush = raw_aio_flush,
.bdrv_discard = raw_discard,
.bdrv_is_inserted = raw_is_inserted,
.bdrv_eject = raw_eject,

7
block_int.h
View File

@ -72,6 +72,8 @@ struct BlockDriver {
BlockDriverCompletionFunc *cb, void *opaque);
BlockDriverAIOCB *(*bdrv_aio_flush)(BlockDriverState *bs,
BlockDriverCompletionFunc *cb, void *opaque);
int (*bdrv_discard)(BlockDriverState *bs, int64_t sector_num,
int nb_sectors);
int (*bdrv_aio_multiwrite)(BlockDriverState *bs, BlockRequest *reqs,
int num_reqs);
@ -227,6 +229,7 @@ typedef struct BlockConf {
uint16_t min_io_size;
uint32_t opt_io_size;
int32_t bootindex;
uint32_t discard_granularity;
} BlockConf;
static inline unsigned int get_physical_block_exp(BlockConf *conf)
@ -250,6 +253,8 @@ static inline unsigned int get_physical_block_exp(BlockConf *conf)
_conf.physical_block_size, 512), \
DEFINE_PROP_UINT16("min_io_size", _state, _conf.min_io_size, 0), \
DEFINE_PROP_UINT32("opt_io_size", _state, _conf.opt_io_size, 0), \
DEFINE_PROP_INT32("bootindex", _state, _conf.bootindex, -1) \
DEFINE_PROP_INT32("bootindex", _state, _conf.bootindex, -1), \
DEFINE_PROP_UINT32("discard_granularity", _state, \
_conf.discard_granularity, 0)
#endif /* BLOCK_INT_H */