diff options
| author | Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> | 2012-02-07 13:27:25 +0000 |
|---|---|---|
| committer | Kevin Wolf <kwolf@redhat.com> | 2012-02-09 16:17:50 +0100 |
| commit | f08f2ddae078e8a7683f8b16da8e0cc3029c7b89 (patch) | |
| tree | bfb375876998a1c425ce6bb018dcd923118b7aea /trace-events | |
| parent | 1a6d39fd71ddf90c5b76026cac4d5ff51fbaf8d8 (diff) | |
| download | qemu-f08f2ddae078e8a7683f8b16da8e0cc3029c7b89.tar.gz | |
block: add .bdrv_co_write_zeroes() interface
The ability to zero regions of an image file is a useful primitive for
higher-level features such as image streaming or zero write detection.
Image formats may support an optimized metadata representation instead
of writing zeroes into the image file. This allows zero writes to be
potentially faster than regular write operations and also preserve
sparseness of the image file.
The .bdrv_co_write_zeroes() interface should be implemented by block
drivers that wish to provide efficient zeroing.
Note that this operation is different from the discard operation, which
may leave the contents of the region indeterminate. That means
discarded blocks are not guaranteed to contain zeroes and may contain
junk data instead.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'trace-events')
| -rw-r--r-- | trace-events | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/trace-events b/trace-events index 5d05749643..3372087ed9 100644 --- a/trace-events +++ b/trace-events @@ -67,6 +67,7 @@ bdrv_lock_medium(void *bs, bool locked) "bs %p locked %d" bdrv_co_readv(void *bs, int64_t sector_num, int nb_sector) "bs %p sector_num %"PRId64" nb_sectors %d" bdrv_co_copy_on_readv(void *bs, int64_t sector_num, int nb_sector) "bs %p sector_num %"PRId64" nb_sectors %d" bdrv_co_writev(void *bs, int64_t sector_num, int nb_sector) "bs %p sector_num %"PRId64" nb_sectors %d" +bdrv_co_write_zeroes(void *bs, int64_t sector_num, int nb_sector) "bs %p sector_num %"PRId64" nb_sectors %d" bdrv_co_io_em(void *bs, int64_t sector_num, int nb_sectors, int is_write, void *acb) "bs %p sector_num %"PRId64" nb_sectors %d is_write %d acb %p" bdrv_co_do_copy_on_readv(void *bs, int64_t sector_num, int nb_sectors, int64_t cluster_sector_num, int cluster_nb_sectors) "bs %p sector_num %"PRId64" nb_sectors %d cluster_sector_num %"PRId64" cluster_nb_sectors %d" |