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block: Respect underlying file's EOF 

When falling through to the underlying file in
bdrv_co_get_block_status(), if it returns that the query offset is
beyond the file end (by setting *pnum to 0), return the range to be
zero and do not let the number of sectors for which information could be
obtained be overwritten.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Max Reitz 2014-10-22 17:00:15 +02:00 committed by Kevin Wolf
parent 7f75a07d50
commit 59c9a95fd2
1 changed files with 13 additions and 2 deletions
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15
block.c
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@ -3954,13 +3954,24 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs,
if (bs->file && if (bs->file &&
(ret & BDRV_BLOCK_DATA) && !(ret & BDRV_BLOCK_ZERO) && (ret & BDRV_BLOCK_DATA) && !(ret & BDRV_BLOCK_ZERO) &&
(ret & BDRV_BLOCK_OFFSET_VALID)) { (ret & BDRV_BLOCK_OFFSET_VALID)) {
int file_pnum;
ret2 = bdrv_co_get_block_status(bs->file, ret >> BDRV_SECTOR_BITS, ret2 = bdrv_co_get_block_status(bs->file, ret >> BDRV_SECTOR_BITS,
*pnum, pnum); *pnum, &file_pnum);
if (ret2 >= 0) { if (ret2 >= 0) {
/* Ignore errors. This is just providing extra information, it /* Ignore errors. This is just providing extra information, it
* is useful but not necessary. * is useful but not necessary.
*/ */
ret |= (ret2 & BDRV_BLOCK_ZERO); if (!file_pnum) {
/* !file_pnum indicates an offset at or beyond the EOF; it is
* perfectly valid for the format block driver to point to such
* offsets, so catch it and mark everything as zero */
ret |= BDRV_BLOCK_ZERO;
} else {
/* Limit request to the range reported by the protocol driver */
*pnum = file_pnum;
ret |= (ret2 & BDRV_BLOCK_ZERO);
}
} }
} }