From 4333bb71405f58a8dc8d3255feb3ca5960b0daf8 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Wed, 4 Sep 2013 19:00:29 +0200 Subject: [PATCH] block: define get_block_status return value Define the return value of get_block_status. Bits 0, 1, 2 and 9-62 are valid; bit 63 (the sign bit) is reserved for errors. Bits 3-8 are left for future extensions. The return code is compatible with the old is_allocated API: if a driver only returns 0 or 1 (aka BDRV_BLOCK_DATA) like is_allocated used to, clients of is_allocated will not have any change in behavior. Still, we will return more precise information in the next patches and the new definition of bdrv_is_allocated is already prepared for this. Reviewed-by: Eric Blake Signed-off-by: Paolo Bonzini Signed-off-by: Stefan Hajnoczi --- block.c | 10 ++++++++-- include/block/block.h | 26 ++++++++++++++++++++++++++ 2 files changed, 34 insertions(+), 2 deletions(-) diff --git a/block.c b/block.c index a5bfe74ef6..97406ec7bd 100644 --- a/block.c +++ b/block.c @@ -3093,7 +3093,7 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs, if (!bs->drv->bdrv_co_get_block_status) { *pnum = nb_sectors; - return 1; + return BDRV_BLOCK_DATA; } return bs->drv->bdrv_co_get_block_status(bs, sector_num, nb_sectors, pnum); @@ -3143,7 +3143,13 @@ int64_t bdrv_get_block_status(BlockDriverState *bs, int64_t sector_num, int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num, int nb_sectors, int *pnum) { - return bdrv_get_block_status(bs, sector_num, nb_sectors, pnum); + int64_t ret = bdrv_get_block_status(bs, sector_num, nb_sectors, pnum); + if (ret < 0) { + return ret; + } + return + (ret & BDRV_BLOCK_DATA) || + ((ret & BDRV_BLOCK_ZERO) && !bdrv_has_zero_init(bs)); } /* diff --git a/include/block/block.h b/include/block/block.h index 0b83321419..728ec1aebf 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -81,6 +81,32 @@ typedef struct BlockDevOps { #define BDRV_SECTOR_SIZE (1ULL << BDRV_SECTOR_BITS) #define BDRV_SECTOR_MASK ~(BDRV_SECTOR_SIZE - 1) +/* BDRV_BLOCK_DATA: data is read from bs->file or another file + * BDRV_BLOCK_ZERO: sectors read as zero + * BDRV_BLOCK_OFFSET_VALID: sector stored in bs->file as raw data + * + * If BDRV_BLOCK_OFFSET_VALID is set, bits 9-62 represent the offset in + * bs->file where sector data can be read from as raw data. + * + * DATA == 0 && ZERO == 0 means that data is read from backing_hd if present. + * + * DATA ZERO OFFSET_VALID + * t t t sectors read as zero, bs->file is zero at offset + * t f t sectors read as valid from bs->file at offset + * f t t sectors preallocated, read as zero, bs->file not + * necessarily zero at offset + * f f t sectors preallocated but read from backing_hd, + * bs->file contains garbage at offset + * t t f sectors preallocated, read as zero, unknown offset + * t f f sectors read from unknown file or offset + * f t f not allocated or unknown offset, read as zero + * f f f not allocated or unknown offset, read from backing_hd + */ +#define BDRV_BLOCK_DATA 1 +#define BDRV_BLOCK_ZERO 2 +#define BDRV_BLOCK_OFFSET_VALID 4 +#define BDRV_BLOCK_OFFSET_MASK BDRV_SECTOR_MASK + typedef enum { BDRV_ACTION_REPORT, BDRV_ACTION_IGNORE, BDRV_ACTION_STOP } BlockErrorAction;