| Message ID | 7aabf75e26ea1d60102fd0e1adfcd104aa3689c8.1362580930.git.jcody@redhat.com |
|---|---|
| State | New |
| Headers | show |
On Wed, Mar 06, 2013 at 09:48:43AM -0500, Jeff Cody wrote: > @@ -958,12 +960,150 @@ exit: > return ret; > } > > +/* > + * Allocate a new payload block at the end of the file. > + * > + * Allocation will happen at 1MB alignment inside the file > + * > + * Returns the file offset start of the new payload block > + */ > +static int vhdx_allocate_block(BlockDriverState *bs, BDRVVHDXState *s, > + uint64_t *new_offset) > +{ > + *new_offset = bdrv_getlength(bs->file); > + > + /* per the spec, the address for a block is in units of 1MB */ > + if (*new_offset % (1024*1024)) { > + *new_offset = ((*new_offset >> 20) + 1) << 20; /* round up to 1MB */ > + } > + return bdrv_truncate(bs->file, *new_offset + s->block_size); > +} Is it necessary to resize the file? Why not just write at EOF to grow it? > +/* > + * Update the BAT tablet entry with the new file offset, and the new entry > + * state */ > +static int vhdx_update_bat_table_entry(BlockDriverState *bs, BDRVVHDXState *s, > + vhdx_sector_info *sinfo, int state) > +{ > + uint64_t bat_tmp; > + uint64_t bat_entry_offset; > + > + /* The BAT entry is a uint64, with 44 bits for the file offset in units of > + * 1MB, and 3 bits for the block state. */ > + s->bat[sinfo->bat_idx] = ((sinfo->file_offset>>20) << > + VHDX_BAT_FILE_OFF_BITS); > + > + s->bat[sinfo->bat_idx] |= state & VHDX_BAT_STATE_BIT_MASK; > > + bat_tmp = cpu_to_le64(s->bat[sinfo->bat_idx]); > + bat_entry_offset = s->bat_offset + sinfo->bat_idx * sizeof(vhdx_bat_entry); > + > + return bdrv_pwrite_sync(bs->file, bat_entry_offset, &bat_tmp, > + sizeof(vhdx_bat_entry)); > +} > > static coroutine_fn int vhdx_co_writev(BlockDriverState *bs, int64_t sector_num, > int nb_sectors, QEMUIOVector *qiov) > { > - return -ENOTSUP; > + int ret = -ENOTSUP; > + BDRVVHDXState *s = bs->opaque; > + vhdx_sector_info sinfo; > + uint64_t bytes_done = 0; > + QEMUIOVector hd_qiov; > + > + qemu_iovec_init(&hd_qiov, qiov->niov); > + > + qemu_co_mutex_lock(&s->lock); > + > + /* Per the spec, on the first write of guest-visible data to the file the > + * data write guid must be updated in the header */ > + if (s->first_visible_write) { > + s->first_visible_write = false; > + vhdx_update_headers(bs, s, true); > + } > + > + while (nb_sectors > 0) { > + if (s->params.data_bits & VHDX_PARAMS_HAS_PARENT) { > + /* not supported yet */ > + ret = -ENOTSUP; > + goto exit; > + } else { > + vhdx_block_translate(s, sector_num, nb_sectors, &sinfo); > + > + qemu_iovec_reset(&hd_qiov); > + qemu_iovec_concat(&hd_qiov, qiov, bytes_done, sinfo.bytes_avail); > + /* check the payload block state */ > + switch (s->bat[sinfo.bat_idx] & VHDX_BAT_STATE_BIT_MASK) { > + case PAYLOAD_BLOCK_ZERO: > + /* 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 */ > + > + /* TODO: queue another write of zero buffers if the host OS does > + * not zero-fill on file extension */ > + > + /* fall through */ > + case PAYLOAD_BLOCK_NOT_PRESENT: /* fall through */ > + case PAYLOAD_BLOCK_UNMAPPED: /* fall through */ > + case PAYLOAD_BLOCK_UNDEFINED: /* fall through */ > + 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 */ > + ret = vhdx_update_bat_table_entry(bs, s, &sinfo, > + PAYLOAD_BLOCK_FULL_PRESENT); > + if (ret < 0) { > + goto exit; > + } The BAT table entry must be written after data is already on disk. Otherwise a crash partway through would leave the BAT table pointing to undefined data. Do you need to use the log to ensure this?
On Thu, Mar 07, 2013 at 04:59:05PM +0100, Stefan Hajnoczi wrote: > On Wed, Mar 06, 2013 at 09:48:43AM -0500, Jeff Cody wrote: > > @@ -958,12 +960,150 @@ exit: > > return ret; > > } > > > > +/* > > + * Allocate a new payload block at the end of the file. > > + * > > + * Allocation will happen at 1MB alignment inside the file > > + * > > + * Returns the file offset start of the new payload block > > + */ > > +static int vhdx_allocate_block(BlockDriverState *bs, BDRVVHDXState *s, > > + uint64_t *new_offset) > > +{ > > + *new_offset = bdrv_getlength(bs->file); > > + > > + /* per the spec, the address for a block is in units of 1MB */ > > + if (*new_offset % (1024*1024)) { > > + *new_offset = ((*new_offset >> 20) + 1) << 20; /* round up to 1MB */ > > + } > > + return bdrv_truncate(bs->file, *new_offset + s->block_size); > > +} > > Is it necessary to resize the file? Why not just write at EOF to grow > it? > After the recent bdrv_truncate() discussion, I think that may be best. > > +/* > > + * Update the BAT tablet entry with the new file offset, and the new entry > > + * state */ > > +static int vhdx_update_bat_table_entry(BlockDriverState *bs, BDRVVHDXState *s, > > + vhdx_sector_info *sinfo, int state) > > +{ > > + uint64_t bat_tmp; > > + uint64_t bat_entry_offset; > > + > > + /* The BAT entry is a uint64, with 44 bits for the file offset in units of > > + * 1MB, and 3 bits for the block state. */ > > + s->bat[sinfo->bat_idx] = ((sinfo->file_offset>>20) << > > + VHDX_BAT_FILE_OFF_BITS); > > + > > + s->bat[sinfo->bat_idx] |= state & VHDX_BAT_STATE_BIT_MASK; > > > > + bat_tmp = cpu_to_le64(s->bat[sinfo->bat_idx]); > > + bat_entry_offset = s->bat_offset + sinfo->bat_idx * sizeof(vhdx_bat_entry); > > + > > + return bdrv_pwrite_sync(bs->file, bat_entry_offset, &bat_tmp, > > + sizeof(vhdx_bat_entry)); > > +} > > > > static coroutine_fn int vhdx_co_writev(BlockDriverState *bs, int64_t sector_num, > > int nb_sectors, QEMUIOVector *qiov) > > { > > - return -ENOTSUP; > > + int ret = -ENOTSUP; > > + BDRVVHDXState *s = bs->opaque; > > + vhdx_sector_info sinfo; > > + uint64_t bytes_done = 0; > > + QEMUIOVector hd_qiov; > > + > > + qemu_iovec_init(&hd_qiov, qiov->niov); > > + > > + qemu_co_mutex_lock(&s->lock); > > + > > + /* Per the spec, on the first write of guest-visible data to the file the > > + * data write guid must be updated in the header */ > > + if (s->first_visible_write) { > > + s->first_visible_write = false; > > + vhdx_update_headers(bs, s, true); > > + } > > + > > + while (nb_sectors > 0) { > > + if (s->params.data_bits & VHDX_PARAMS_HAS_PARENT) { > > + /* not supported yet */ > > + ret = -ENOTSUP; > > + goto exit; > > + } else { > > + vhdx_block_translate(s, sector_num, nb_sectors, &sinfo); > > + > > + qemu_iovec_reset(&hd_qiov); > > + qemu_iovec_concat(&hd_qiov, qiov, bytes_done, sinfo.bytes_avail); > > + /* check the payload block state */ > > + switch (s->bat[sinfo.bat_idx] & VHDX_BAT_STATE_BIT_MASK) { > > + case PAYLOAD_BLOCK_ZERO: > > + /* 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 */ > > + > > + /* TODO: queue another write of zero buffers if the host OS does > > + * not zero-fill on file extension */ > > + > > + /* fall through */ > > + case PAYLOAD_BLOCK_NOT_PRESENT: /* fall through */ > > + case PAYLOAD_BLOCK_UNMAPPED: /* fall through */ > > + case PAYLOAD_BLOCK_UNDEFINED: /* fall through */ > > + 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 */ > > + ret = vhdx_update_bat_table_entry(bs, s, &sinfo, > > + PAYLOAD_BLOCK_FULL_PRESENT); > > + if (ret < 0) { > > + goto exit; > > + } > > The BAT table entry must be written after data is already on disk. > Otherwise a crash partway through would leave the BAT table pointing to > undefined data. > > Do you need to use the log to ensure this? Yes, indeed. The log support is what I am working on now - all metadata and BAT writes are supposed to go through the log, for this reason. The next version will have log support, and so I will use that for the BAT writes (and any other metadata writes, except the header).
diff --git a/block/vhdx.c b/block/vhdx.c index 13d1e7f..316a5d8 100644 --- a/block/vhdx.c +++ b/block/vhdx.c @@ -165,6 +165,7 @@ typedef struct BDRVVHDXState { vhdx_bat_entry *bat; uint64_t bat_offset; + bool first_visible_write; ms_guid session_guid; @@ -782,6 +783,7 @@ static int vhdx_open(BlockDriverState *bs, int flags) int i; s->bat = NULL; + s->first_visible_write = true; qemu_co_mutex_init(&s->lock); @@ -829,7 +831,7 @@ static int vhdx_open(BlockDriverState *bs, int flags) vhdx_update_headers(bs, s, false); } - /* TODO: differencing files, write */ + /* TODO: differencing files */ return 0; fail: @@ -958,12 +960,150 @@ exit: return ret; } +/* + * Allocate a new payload block at the end of the file. + * + * Allocation will happen at 1MB alignment inside the file + * + * Returns the file offset start of the new payload block + */ +static int vhdx_allocate_block(BlockDriverState *bs, BDRVVHDXState *s, + uint64_t *new_offset) +{ + *new_offset = bdrv_getlength(bs->file); + + /* per the spec, the address for a block is in units of 1MB */ + if (*new_offset % (1024*1024)) { + *new_offset = ((*new_offset >> 20) + 1) << 20; /* round up to 1MB */ + } + return bdrv_truncate(bs->file, *new_offset + s->block_size); +} + +/* + * Update the BAT tablet entry with the new file offset, and the new entry + * state */ +static int vhdx_update_bat_table_entry(BlockDriverState *bs, BDRVVHDXState *s, + vhdx_sector_info *sinfo, int state) +{ + uint64_t bat_tmp; + uint64_t bat_entry_offset; + + /* The BAT entry is a uint64, with 44 bits for the file offset in units of + * 1MB, and 3 bits for the block state. */ + s->bat[sinfo->bat_idx] = ((sinfo->file_offset>>20) << + VHDX_BAT_FILE_OFF_BITS); + + s->bat[sinfo->bat_idx] |= state & VHDX_BAT_STATE_BIT_MASK; + bat_tmp = cpu_to_le64(s->bat[sinfo->bat_idx]); + bat_entry_offset = s->bat_offset + sinfo->bat_idx * sizeof(vhdx_bat_entry); + + return bdrv_pwrite_sync(bs->file, bat_entry_offset, &bat_tmp, + sizeof(vhdx_bat_entry)); +} static coroutine_fn int vhdx_co_writev(BlockDriverState *bs, int64_t sector_num, int nb_sectors, QEMUIOVector *qiov) { - return -ENOTSUP; + int ret = -ENOTSUP; + BDRVVHDXState *s = bs->opaque; + vhdx_sector_info sinfo; + uint64_t bytes_done = 0; + QEMUIOVector hd_qiov; + + qemu_iovec_init(&hd_qiov, qiov->niov); + + qemu_co_mutex_lock(&s->lock); + + /* Per the spec, on the first write of guest-visible data to the file the + * data write guid must be updated in the header */ + if (s->first_visible_write) { + s->first_visible_write = false; + vhdx_update_headers(bs, s, true); + } + + while (nb_sectors > 0) { + if (s->params.data_bits & VHDX_PARAMS_HAS_PARENT) { + /* not supported yet */ + ret = -ENOTSUP; + goto exit; + } else { + vhdx_block_translate(s, sector_num, nb_sectors, &sinfo); + + qemu_iovec_reset(&hd_qiov); + qemu_iovec_concat(&hd_qiov, qiov, bytes_done, sinfo.bytes_avail); + /* check the payload block state */ + switch (s->bat[sinfo.bat_idx] & VHDX_BAT_STATE_BIT_MASK) { + case PAYLOAD_BLOCK_ZERO: + /* 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 */ + + /* TODO: queue another write of zero buffers if the host OS does + * not zero-fill on file extension */ + + /* fall through */ + case PAYLOAD_BLOCK_NOT_PRESENT: /* fall through */ + case PAYLOAD_BLOCK_UNMAPPED: /* fall through */ + case PAYLOAD_BLOCK_UNDEFINED: /* fall through */ + 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 */ + ret = vhdx_update_bat_table_entry(bs, s, &sinfo, + PAYLOAD_BLOCK_FULL_PRESENT); + if (ret < 0) { + goto exit; + } + /* 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 */ + sinfo.file_offset += sinfo.block_offset; + /* fall through */ + case PAYLOAD_BLOCK_FULL_PRESENT: + /* if the file offset address is in the header zone, + * there is a problem */ + if (sinfo.file_offset < (1024*1024)) { + ret = -EFAULT; + goto exit; + } + /* block exists, so we can just overwrite it */ + qemu_co_mutex_unlock(&s->lock); + ret = bdrv_co_writev(bs->file, + sinfo.file_offset>>BDRV_SECTOR_BITS, + sinfo.sectors_avail, &hd_qiov); + qemu_co_mutex_lock(&s->lock); + if (ret < 0) { + goto exit; + } + break; + case PAYLOAD_BLOCK_PARTIALLY_PRESENT: + /* we don't yet support difference files, fall through + * to error */ + default: + ret = -EIO; + goto exit; + break; + } + + nb_sectors -= sinfo.sectors_avail; + sector_num += sinfo.sectors_avail; + bytes_done += sinfo.bytes_avail; + + } + } + +exit: + qemu_co_mutex_unlock(&s->lock); + return ret; }
This adds in write support for VHDX images. This supports writing to both dynamic and fixed VHDX images. Differencing images are still unsupported. Signed-off-by: Jeff Cody <jcody@redhat.com> --- block/vhdx.c | 144 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 142 insertions(+), 2 deletions(-)