mirror of https://gitee.com/openkylin/qemu.git
raw-posix: Fix raw_co_get_block_status() after EOF
As its comment states, raw_co_get_block_status() should unconditionally return 0 and set *pnum to 0 for after EOF. An assertion after lseek(..., SEEK_HOLE) tried to catch this case by asserting that errno != -ENXIO (which would indicate a position after the EOF); but it should be errno != ENXIO instead. Regardless of that, there should be no such assertion at all. If bdrv_getlength() returned an outdated value and the image has been resized outside of qemu, lseek() will return with errno == ENXIO. Just return that value as an error then. Setting *pnum to 0 and returning 0 should not be done here, as in that case we should update the device length as well. So, from qemu's perspective, the file has not been resized; it's just that there was an error querying sectors beyond a certain point (the actual file size). Additionally, nb_sectors should be clamped against the image end. This was probably not an issue if FIEMAP or SEEK_HOLE/SEEK_DATA worked, but the fallback did not take this case into account. Reported-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Message-id: 1414148280-17949-2-git-send-email-mreitz@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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@ -1535,10 +1535,6 @@ static int64_t try_seek_hole(BlockDriverState *bs, off_t start, off_t *data,
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*hole = lseek(s->fd, start, SEEK_HOLE);
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if (*hole == -1) {
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/* -ENXIO indicates that sector_num was past the end of the file.
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* There is a virtual hole there. */
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assert(errno != -ENXIO);
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return -errno;
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}
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@ -1578,6 +1574,7 @@ static int64_t coroutine_fn raw_co_get_block_status(BlockDriverState *bs,
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int nb_sectors, int *pnum)
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{
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off_t start, data = 0, hole = 0;
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int64_t total_size;
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int64_t ret;
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ret = fd_open(bs);
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@ -1586,6 +1583,15 @@ static int64_t coroutine_fn raw_co_get_block_status(BlockDriverState *bs,
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}
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start = sector_num * BDRV_SECTOR_SIZE;
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total_size = bdrv_getlength(bs);
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if (total_size < 0) {
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return total_size;
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} else if (start >= total_size) {
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*pnum = 0;
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return 0;
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} else if (start + nb_sectors * BDRV_SECTOR_SIZE > total_size) {
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nb_sectors = DIV_ROUND_UP(total_size - start, BDRV_SECTOR_SIZE);
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}
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ret = try_seek_hole(bs, start, &data, &hole, pnum);
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if (ret < 0) {
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