diff options
| -rw-r--r-- | block/vhdx.c | 89 |
1 files changed, 51 insertions, 38 deletions
diff --git a/block/vhdx.c b/block/vhdx.c index e11fb74..53e7564 100644 --- a/block/vhdx.c +++ b/block/vhdx.c @@ -1240,12 +1240,16 @@ exit: /* * Allocate a new payload block at the end of the file. * - * Allocation will happen at 1MB alignment inside the file + * Allocation will happen at 1MB alignment inside the file. + * + * If @need_zero is set on entry but not cleared on return, then truncation + * could not guarantee that the new portion reads as zero, and the caller + * will take care of it instead. * * Returns the file offset start of the new payload block */ static int vhdx_allocate_block(BlockDriverState *bs, BDRVVHDXState *s, - uint64_t *new_offset) + uint64_t *new_offset, bool *need_zero) { int64_t current_len; @@ -1262,6 +1266,17 @@ static int vhdx_allocate_block(BlockDriverState *bs, BDRVVHDXState *s, return -EINVAL; } + if (*need_zero) { + int ret; + + ret = bdrv_truncate(bs->file, *new_offset + s->block_size, false, + PREALLOC_MODE_OFF, BDRV_REQ_ZERO_WRITE, NULL); + if (ret != -ENOTSUP) { + *need_zero = false; + return ret; + } + } + return bdrv_truncate(bs->file, *new_offset + s->block_size, false, PREALLOC_MODE_OFF, 0, NULL); } @@ -1355,18 +1370,38 @@ static coroutine_fn int vhdx_co_writev(BlockDriverState *bs, int64_t sector_num, /* in this case, we need to preserve zero writes for * data that is not part of this write, so we must pad * the rest of the buffer to zeroes */ - - /* if we are on a posix system with ftruncate() that extends - * a file, then it is zero-filled for us. On Win32, the raw - * layer uses SetFilePointer and SetFileEnd, which does not - * zero fill AFAIK */ - - /* Queue another write of zero buffers if the underlying file - * does not zero-fill on file extension */ - - if (bdrv_has_zero_init_truncate(bs->file->bs) == 0) { - use_zero_buffers = true; - + use_zero_buffers = true; + /* fall through */ + case PAYLOAD_BLOCK_NOT_PRESENT: /* fall through */ + case PAYLOAD_BLOCK_UNMAPPED: + case PAYLOAD_BLOCK_UNMAPPED_v095: + case PAYLOAD_BLOCK_UNDEFINED: + bat_prior_offset = sinfo.file_offset; + ret = vhdx_allocate_block(bs, s, &sinfo.file_offset, + &use_zero_buffers); + if (ret < 0) { + goto exit; + } + /* + * once we support differencing files, this may also be + * partially present + */ + /* update block state to the newly specified state */ + vhdx_update_bat_table_entry(bs, s, &sinfo, &bat_entry, + &bat_entry_offset, + PAYLOAD_BLOCK_FULLY_PRESENT); + bat_update = true; + /* + * Since we just allocated a block, file_offset is the + * beginning of the payload block. It needs to be the + * write address, which includes the offset into the + * block, unless the entire block needs to read as + * zeroes but truncation was not able to provide them, + * in which case we need to fill in the rest. + */ + if (!use_zero_buffers) { + sinfo.file_offset += sinfo.block_offset; + } else { /* zero fill the front, if any */ if (sinfo.block_offset) { iov1.iov_len = sinfo.block_offset; @@ -1378,7 +1413,7 @@ static coroutine_fn int vhdx_co_writev(BlockDriverState *bs, int64_t sector_num, } /* our actual data */ - qemu_iovec_concat(&hd_qiov, qiov, bytes_done, + qemu_iovec_concat(&hd_qiov, qiov, bytes_done, sinfo.bytes_avail); /* zero fill the back, if any */ @@ -1393,29 +1428,7 @@ static coroutine_fn int vhdx_co_writev(BlockDriverState *bs, int64_t sector_num, sectors_to_write += iov2.iov_len >> BDRV_SECTOR_BITS; } } - /* fall through */ - case PAYLOAD_BLOCK_NOT_PRESENT: /* fall through */ - case PAYLOAD_BLOCK_UNMAPPED: - case PAYLOAD_BLOCK_UNMAPPED_v095: - case PAYLOAD_BLOCK_UNDEFINED: - bat_prior_offset = sinfo.file_offset; - ret = vhdx_allocate_block(bs, s, &sinfo.file_offset); - if (ret < 0) { - goto exit; - } - /* once we support differencing files, this may also be - * partially present */ - /* update block state to the newly specified state */ - vhdx_update_bat_table_entry(bs, s, &sinfo, &bat_entry, - &bat_entry_offset, - PAYLOAD_BLOCK_FULLY_PRESENT); - bat_update = true; - /* since we just allocated a block, file_offset is the - * beginning of the payload block. It needs to be the - * write address, which includes the offset into the block */ - if (!use_zero_buffers) { - sinfo.file_offset += sinfo.block_offset; - } + /* fall through */ case PAYLOAD_BLOCK_FULLY_PRESENT: /* if the file offset address is in the header zone, |