diff options
| author | Paolo Bonzini <pbonzini@redhat.com> | 2013-02-08 14:06:11 +0100 |
|---|---|---|
| committer | Kevin Wolf <kwolf@redhat.com> | 2013-02-22 21:29:42 +0100 |
| commit | 9e8f1835ea3ab3be83634f34c1bb8b69cd871766 (patch) | |
| tree | 079db917d1d60678dd098fdf53d3b549dc82191d /include/block/block.h | |
| parent | 9a665b2b8640e464f0a778216fc2dca8d02acf33 (diff) | |
block: implement BDRV_O_UNMAP
It is better to present homogeneous hardware independent of the storage
technology that is chosen on the host, hence we make discard a host
parameter; the user can choose whether to pass it down to the image
format and protocol, or to ignore it.
Using DISCARD with filesystems can cause very severe fragmentation, so it
is left default-off for now. This can change later when we implement the
"anchor" operation for efficient management of preallocated files.
There is still one choice to make: whether DISCARD has an effect on the
dirty bitmap or not. I chose yes, though there is a disadvantage: if
the guest is buggy and issues discards for data that is in use, there
will be no way to migrate storage for that guest without downgrading
the machine type to an older one.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'include/block/block.h')
| -rw-r--r-- | include/block/block.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/include/block/block.h b/include/block/block.h index b4a24da3e9..0f750d7da3 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -84,6 +84,7 @@ typedef struct BlockDevOps { #define BDRV_O_INCOMING 0x0800 /* consistency hint for incoming migration */ #define BDRV_O_CHECK 0x1000 /* open solely for consistency check */ #define BDRV_O_ALLOW_RDWR 0x2000 /* allow reopen to change from r/o to r/w */ +#define BDRV_O_UNMAP 0x4000 /* execute guest UNMAP/TRIM operations */ #define BDRV_O_CACHE_MASK (BDRV_O_NOCACHE | BDRV_O_CACHE_WB | BDRV_O_NO_FLUSH) @@ -133,6 +134,7 @@ void bdrv_swap(BlockDriverState *bs_new, BlockDriverState *bs_old); void bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top); void bdrv_delete(BlockDriverState *bs); int bdrv_parse_cache_flags(const char *mode, int *flags); +int bdrv_parse_discard_flags(const char *mode, int *flags); int bdrv_file_open(BlockDriverState **pbs, const char *filename, int flags); int bdrv_open_backing_file(BlockDriverState *bs); int bdrv_open(BlockDriverState *bs, const char *filename, int flags, |