diff options
| -rw-r--r-- | block/io.c | 12 | ||||
| -rw-r--r-- | include/block/block.h | 7 |
2 files changed, 17 insertions, 2 deletions
diff --git a/block/io.c b/block/io.c index 952372c2bb..dfc153b8d8 100644 --- a/block/io.c +++ b/block/io.c @@ -1015,6 +1015,7 @@ static int coroutine_fn bdrv_driver_preadv(BlockDriverState *bs, unsigned int nb_sectors; assert(!(flags & ~BDRV_REQ_MASK)); + assert(!(flags & BDRV_REQ_NO_FALLBACK)); if (!drv) { return -ENOMEDIUM; @@ -1061,6 +1062,7 @@ static int coroutine_fn bdrv_driver_pwritev(BlockDriverState *bs, int ret; assert(!(flags & ~BDRV_REQ_MASK)); + assert(!(flags & BDRV_REQ_NO_FALLBACK)); if (!drv) { return -ENOMEDIUM; @@ -1467,6 +1469,10 @@ static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs, return -ENOMEDIUM; } + if ((flags & ~bs->supported_zero_flags) & BDRV_REQ_NO_FALLBACK) { + return -ENOTSUP; + } + assert(alignment % bs->bl.request_alignment == 0); head = offset % alignment; tail = (offset + bytes) % alignment; @@ -1510,7 +1516,7 @@ static int coroutine_fn bdrv_co_do_pwrite_zeroes(BlockDriverState *bs, assert(!bs->supported_zero_flags); } - if (ret == -ENOTSUP) { + if (ret == -ENOTSUP && !(flags & BDRV_REQ_NO_FALLBACK)) { /* Fall back to bounce buffer if write zeroes is unsupported */ BdrvRequestFlags write_flags = flags & ~BDRV_REQ_ZERO_WRITE; @@ -2949,6 +2955,10 @@ static int coroutine_fn bdrv_co_copy_range_internal( BdrvTrackedRequest req; int ret; + /* TODO We can support BDRV_REQ_NO_FALLBACK here */ + assert(!(read_flags & BDRV_REQ_NO_FALLBACK)); + assert(!(write_flags & BDRV_REQ_NO_FALLBACK)); + if (!dst || !dst->bs) { return -ENOMEDIUM; } diff --git a/include/block/block.h b/include/block/block.h index e452988b66..c7a26199aa 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -83,8 +83,13 @@ typedef enum { */ BDRV_REQ_SERIALISING = 0x80, + /* Execute the request only if the operation can be offloaded or otherwise + * be executed efficiently, but return an error instead of using a slow + * fallback. */ + BDRV_REQ_NO_FALLBACK = 0x100, + /* Mask of valid flags */ - BDRV_REQ_MASK = 0xff, + BDRV_REQ_MASK = 0x1ff, } BdrvRequestFlags; typedef struct BlockSizes { |