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 <eblake@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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block.c
10
block.c
@ -3093,7 +3093,7 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs,
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if (!bs->drv->bdrv_co_get_block_status) {
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*pnum = nb_sectors;
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return 1;
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return BDRV_BLOCK_DATA;
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}
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return bs->drv->bdrv_co_get_block_status(bs, sector_num, nb_sectors, pnum);
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@ -3143,7 +3143,13 @@ int64_t bdrv_get_block_status(BlockDriverState *bs, int64_t sector_num,
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int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num,
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int nb_sectors, int *pnum)
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{
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return bdrv_get_block_status(bs, sector_num, nb_sectors, pnum);
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int64_t ret = bdrv_get_block_status(bs, sector_num, nb_sectors, pnum);
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if (ret < 0) {
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return ret;
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}
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return
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(ret & BDRV_BLOCK_DATA) ||
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((ret & BDRV_BLOCK_ZERO) && !bdrv_has_zero_init(bs));
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}
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/*
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@ -81,6 +81,32 @@ typedef struct BlockDevOps {
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#define BDRV_SECTOR_SIZE (1ULL << BDRV_SECTOR_BITS)
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#define BDRV_SECTOR_MASK ~(BDRV_SECTOR_SIZE - 1)
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/* BDRV_BLOCK_DATA: data is read from bs->file or another file
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* BDRV_BLOCK_ZERO: sectors read as zero
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* BDRV_BLOCK_OFFSET_VALID: sector stored in bs->file as raw data
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*
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* If BDRV_BLOCK_OFFSET_VALID is set, bits 9-62 represent the offset in
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* bs->file where sector data can be read from as raw data.
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*
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* DATA == 0 && ZERO == 0 means that data is read from backing_hd if present.
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*
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* DATA ZERO OFFSET_VALID
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* t t t sectors read as zero, bs->file is zero at offset
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* t f t sectors read as valid from bs->file at offset
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* f t t sectors preallocated, read as zero, bs->file not
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* necessarily zero at offset
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* f f t sectors preallocated but read from backing_hd,
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* bs->file contains garbage at offset
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* t t f sectors preallocated, read as zero, unknown offset
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* t f f sectors read from unknown file or offset
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* f t f not allocated or unknown offset, read as zero
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* f f f not allocated or unknown offset, read from backing_hd
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*/
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#define BDRV_BLOCK_DATA 1
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#define BDRV_BLOCK_ZERO 2
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#define BDRV_BLOCK_OFFSET_VALID 4
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#define BDRV_BLOCK_OFFSET_MASK BDRV_SECTOR_MASK
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typedef enum {
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BDRV_ACTION_REPORT, BDRV_ACTION_IGNORE, BDRV_ACTION_STOP
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} BlockErrorAction;
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