[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Qemu-devel] [RFC PATCH v1] Support vhd type VHD_DIFFERENCING
|
From: |
Ding xiao |
|
Subject: |
[Qemu-devel] [RFC PATCH v1] Support vhd type VHD_DIFFERENCING |
|
Date: |
Tue, 1 Jul 2014 17:45:19 +0800 |
Now qemu only supports vhd type VHD_FIXED and VHD_DYNAMIC,
so qemu can't read snapshot volume of vhd, and can't
support other storage features of vhd file.
this patch add read parent information in function
"vpc_open", read bitmap in "vpc_read", and change bitmap
in "vpc_write".
Signed-off-by: Ding xiao <address@hidden>
---
block/vpc.c | 302 ++++++++++++++++++++++++++++++++++++++++++++++++++---------
1 files changed, 259 insertions(+), 43 deletions(-)
diff --git a/block/vpc.c b/block/vpc.c
index 798d854..3b888b6 100644
--- a/block/vpc.c
+++ b/block/vpc.c
@@ -33,6 +33,10 @@
/**************************************************************/
#define HEADER_SIZE 512
+#define DYNAMIC_HEADER_SIZE 1024
+#define PARENT_LOCATOR_NUM 8
+#define TBBATMAP_HEAD_SIZE 28
+#define MACX 0x5863614d
//#define CACHE
@@ -138,6 +142,18 @@ typedef struct BDRVVPCState {
Error *migration_blocker;
} BDRVVPCState;
+typedef struct vhd_tdbatmap_header {
+ char magic[8]; /* "tdbatmap"*/
+
+ /* byte offset to batmap*/
+ uint64_t batmap_offset;
+
+ /* Offset of the Block Allocation Table (BAT)*/
+ uint32_t batmap_size;
+ uint32_t batmap_version;
+ uint32_t checksum;
+} QEMU_PACKED VHDTdBatmapHeader;
+
static uint32_t vpc_checksum(uint8_t* buf, size_t size)
{
uint32_t res = 0;
@@ -164,11 +180,16 @@ static int vpc_open(BlockDriverState *bs, QDict *options,
int flags,
int i;
VHDFooter *footer;
VHDDynDiskHeader *dyndisk_header;
- uint8_t buf[HEADER_SIZE];
+ uint8_t dynamic_header_buf[DYNAMIC_HEADER_SIZE];
uint32_t checksum;
uint64_t computed_size;
int disk_type = VHD_DYNAMIC;
int ret;
+ VHDTdBatmapHeader *tdbatmap_header;
+ uint8_t tdbatmap_header_buf[TBBATMAP_HEAD_SIZE];
+ int parent_locator_offset = 0;
+ int data_offset = 0;
+ int data_length = 0;
ret = bdrv_pread(bs->file, 0, s->footer_buf, HEADER_SIZE);
if (ret < 0) {
@@ -231,13 +252,13 @@ static int vpc_open(BlockDriverState *bs, QDict *options,
int flags,
}
if (disk_type == VHD_DYNAMIC) {
- ret = bdrv_pread(bs->file, be64_to_cpu(footer->data_offset), buf,
- HEADER_SIZE);
+ ret = bdrv_pread(bs->file, be64_to_cpu(footer->data_offset),
+ dynamic_header_buf, DYNAMIC_HEADER_SIZE);
if (ret < 0) {
goto fail;
}
- dyndisk_header = (VHDDynDiskHeader *) buf;
+ dyndisk_header = (VHDDynDiskHeader *) dynamic_header_buf;
if (strncmp(dyndisk_header->magic, "cxsparse", 8)) {
ret = -EINVAL;
@@ -282,6 +303,46 @@ static int vpc_open(BlockDriverState *bs, QDict *options,
int flags,
s->free_data_block_offset =
(s->bat_offset + (s->max_table_entries * 4) + 511) & ~511;
+ /* read tdbatmap offset*/
+ ret = bdrv_pread(bs->file, s->free_data_block_offset,
+ tdbatmap_header_buf, TBBATMAP_HEAD_SIZE);
+ if (ret < 0) {
+ goto fail;
+ }
+
+ tdbatmap_header = (VHDTdBatmapHeader *) tdbatmap_header_buf;
+
+ if (!strncmp(tdbatmap_header->magic, "tdbatmap", 8)) {
+ s->free_data_block_offset = be64_to_cpu(
+ tdbatmap_header->batmap_offset)
+ + be32_to_cpu(tdbatmap_header->batmap_size) * 512;
+ }
+
+ /* read backend file*/
+ if (dyndisk_header->parent_name[0] || dyndisk_header->parent_name[1]) {
+ for (i = 0; i < PARENT_LOCATOR_NUM; i++) {
+ data_offset = be64_to_cpu(
+ dyndisk_header->parent_locator[i].data_offset);
+ data_length = be32_to_cpu(
+ dyndisk_header->parent_locator[i].data_length);
+ if (dyndisk_header->parent_locator[i].platform == MACX) {
+ ret = bdrv_pread(bs->file, data_offset + 7,
+ bs->backing_file, data_length - 7);
+ if (ret < 0) {
+ goto fail;
+ }
+ bs->backing_file[data_length - 7] = '\0';
+ }
+ if (data_offset > parent_locator_offset) {
+ parent_locator_offset = data_offset;
+ }
+ }
+ }
+
+ if (parent_locator_offset + 512 > s->free_data_block_offset) {
+ s->free_data_block_offset = parent_locator_offset + 512;
+ }
+
for (i = 0; i < s->max_table_entries; i++) {
be32_to_cpus(&s->pagetable[i]);
if (s->pagetable[i] != 0xFFFFFFFF) {
@@ -364,6 +425,9 @@ static inline int64_t get_sector_offset(BlockDriverState
*bs,
// bitmap each time we write to a new block. This might cause Virtual PC to
// miss sparse read optimization, but it's not a problem in terms of
// correctness.
+
+ /*this will not use*/
+#if 0
if (write && (s->last_bitmap_offset != bitmap_offset)) {
uint8_t bitmap[s->bitmap_size];
@@ -371,6 +435,7 @@ static inline int64_t get_sector_offset(BlockDriverState
*bs,
memset(bitmap, 0xff, s->bitmap_size);
bdrv_pwrite_sync(bs->file, bitmap_offset, bitmap, s->bitmap_size);
}
+#endif
// printf("sector: %" PRIx64 ", index: %x, offset: %x, bioff: %" PRIx64 ",
bloff: %" PRIx64 "\n",
// sector_num, pagetable_index, pageentry_index,
@@ -433,7 +498,7 @@ static int rewrite_footer(BlockDriverState* bs)
*
* Returns the sectors' offset in the image file on success and < 0 on error
*/
-static int64_t alloc_block(BlockDriverState* bs, int64_t sector_num)
+static int64_t alloc_block(BlockDriverState *bs, int64_t sector_num, int diff)
{
BDRVVPCState *s = bs->opaque;
int64_t bat_offset;
@@ -453,7 +518,12 @@ static int64_t alloc_block(BlockDriverState* bs, int64_t
sector_num)
s->pagetable[index] = s->free_data_block_offset / 512;
// Initialize the block's bitmap
- memset(bitmap, 0xff, s->bitmap_size);
+ /* if VHD_DIFFERENCING, will set bitmap to 0x00 mean not use*/
+ if (diff) {
+ memset(bitmap, 0x00, s->bitmap_size);
+ } else {
+ memset(bitmap, 0xff, s->bitmap_size);
+ }
ret = bdrv_pwrite_sync(bs->file, s->free_data_block_offset, bitmap,
s->bitmap_size);
if (ret < 0) {
@@ -493,6 +563,46 @@ static int vpc_get_info(BlockDriverState *bs,
BlockDriverInfo *bdi)
return 0;
}
+static inline int64_t get_sector_offset_diff(BlockDriverState *bs,
+ int64_t sector_num)
+{
+ BDRVVPCState *s = bs->opaque;
+ uint64_t offset = sector_num * 512;
+ uint64_t bitmap_offset;
+ uint32_t pagetable_index, pageentry_index;
+ uint8_t bitmap[s->bitmap_size];
+ uint32_t bitmap_index, bitmapentry_index;
+ int ret;
+
+ pagetable_index = offset / s->block_size;
+ pageentry_index = (offset % s->block_size) / 512;
+
+ if (pagetable_index >= s->max_table_entries) {
+ return -1;
+ }
+
+ if (s->pagetable[pagetable_index] == 0xffffffff) {
+ return -2;
+ }
+
+ bitmap_offset = 512 * (uint64_t) s->pagetable[pagetable_index];
+
+ ret = bdrv_pread(bs->file, bitmap_offset, bitmap, s->bitmap_size);
+ if (ret < 0) {
+ return -1;
+ }
+
+ bitmap_index = pageentry_index / 8;
+ bitmapentry_index = 7 - pageentry_index % 8;
+
+ if (bitmap[bitmap_index] & 0x01 << bitmapentry_index) {
+ return bitmap_offset + s->bitmap_size + (512 * pageentry_index);
+ } else {
+ return -2;
+ }
+}
+
+
static int vpc_read(BlockDriverState *bs, int64_t sector_num,
uint8_t *buf, int nb_sectors)
{
@@ -501,33 +611,64 @@ static int vpc_read(BlockDriverState *bs, int64_t
sector_num,
int64_t offset;
int64_t sectors, sectors_per_block;
VHDFooter *footer = (VHDFooter *) s->footer_buf;
+ QEMUIOVector hd_qiov;
+ struct iovec qiov;
if (cpu_to_be32(footer->type) == VHD_FIXED) {
return bdrv_read(bs->file, sector_num, buf, nb_sectors);
- }
- while (nb_sectors > 0) {
- offset = get_sector_offset(bs, sector_num, 0);
+ } else if (cpu_to_be32(footer->type) == VHD_DYNAMIC) {
+ while (nb_sectors > 0) {
+ offset = get_sector_offset(bs, sector_num, 0);
+
+ sectors_per_block = s->block_size >> BDRV_SECTOR_BITS;
+ sectors = sectors_per_block - (sector_num % sectors_per_block);
+ if (sectors > nb_sectors) {
+ sectors = nb_sectors;
+ }
- sectors_per_block = s->block_size >> BDRV_SECTOR_BITS;
- sectors = sectors_per_block - (sector_num % sectors_per_block);
- if (sectors > nb_sectors) {
- sectors = nb_sectors;
+ if (offset == -1) {
+ memset(buf, 0, sectors * BDRV_SECTOR_SIZE);
+ } else {
+ ret = bdrv_pread(bs->file, offset, buf,
+ sectors * BDRV_SECTOR_SIZE);
+ if (ret != sectors * BDRV_SECTOR_SIZE) {
+ return -1;
+ }
+ }
+
+ nb_sectors -= sectors;
+ sector_num += sectors;
+ buf += sectors * BDRV_SECTOR_SIZE;
}
+ } else {
+ while (nb_sectors > 0) {
+ offset = get_sector_offset_diff(bs, sector_num);
+ if (offset == -1) {
+ memset(buf, 0, BDRV_SECTOR_SIZE);
+ } else if (offset == -2) {
+ qiov.iov_base = (void *)buf;
+ qiov.iov_len = 512;
+ hd_qiov.iov = &qiov;
+ hd_qiov.niov = 1;
+ hd_qiov.nalloc = -1;
+ hd_qiov.size = 512;
+ ret = bdrv_co_readv(bs->backing_hd, sector_num, 1, &hd_qiov);
+ if (ret < 0) {
+ return -1;
+ }
- if (offset == -1) {
- memset(buf, 0, sectors * BDRV_SECTOR_SIZE);
- } else {
- ret = bdrv_pread(bs->file, offset, buf,
- sectors * BDRV_SECTOR_SIZE);
- if (ret != sectors * BDRV_SECTOR_SIZE) {
- return -1;
+ } else {
+ ret = bdrv_pread(bs->file, offset, buf, BDRV_SECTOR_SIZE);
+ if (ret != BDRV_SECTOR_SIZE) {
+ return -1;
+ }
}
+ nb_sectors--;
+ sector_num++;
+ buf += BDRV_SECTOR_SIZE;
}
-
- nb_sectors -= sectors;
- sector_num += sectors;
- buf += sectors * BDRV_SECTOR_SIZE;
}
+
return 0;
}
@@ -542,6 +683,45 @@ static coroutine_fn int vpc_co_read(BlockDriverState *bs,
int64_t sector_num,
return ret;
}
+static inline int64_t write_bitmap(BlockDriverState *bs,
+ int64_t sector_num, int64_t sectors)
+{
+ BDRVVPCState *s = bs->opaque;
+ uint64_t offset = sector_num * 512;
+ uint64_t bitmap_offset;
+ uint32_t pagetable_index, pageentry_index;
+ uint8_t bitmap[s->bitmap_size];
+ int i;
+ int ret;
+ int bitmap_index, bitmapbit_index;
+
+ pagetable_index = offset / s->block_size;
+ pageentry_index = (offset % s->block_size) / 512;
+
+ bitmap_offset = 512 * (uint64_t) s->pagetable[pagetable_index];
+
+ ret = bdrv_pread(bs->file, bitmap_offset, bitmap, s->bitmap_size);
+ if (ret < 0) {
+ return -1;
+ }
+
+ for (i = 0; i < sectors; i++) {
+ bitmap_index = pageentry_index/8;
+ bitmapbit_index = 7 - pageentry_index % 8;
+ bitmap[bitmap_index] |= (0x01 << bitmapbit_index);
+ pageentry_index++;
+ }
+
+ ret = bdrv_pwrite(bs->file, bitmap_offset, bitmap, s->bitmap_size);
+ if (ret < 0) {
+ return -1;
+ }
+
+ return 0;
+
+}
+
+
static int vpc_write(BlockDriverState *bs, int64_t sector_num,
const uint8_t *buf, int nb_sectors)
{
@@ -553,30 +733,65 @@ static int vpc_write(BlockDriverState *bs, int64_t
sector_num,
if (cpu_to_be32(footer->type) == VHD_FIXED) {
return bdrv_write(bs->file, sector_num, buf, nb_sectors);
- }
- while (nb_sectors > 0) {
- offset = get_sector_offset(bs, sector_num, 1);
+ } else if (cpu_to_be32(footer->type) == VHD_DYNAMIC) {
+ while (nb_sectors > 0) {
+ offset = get_sector_offset(bs, sector_num, 1);
+
+ sectors_per_block = s->block_size >> BDRV_SECTOR_BITS;
+ sectors = sectors_per_block - (sector_num % sectors_per_block);
+ if (sectors > nb_sectors) {
+ sectors = nb_sectors;
+ }
- sectors_per_block = s->block_size >> BDRV_SECTOR_BITS;
- sectors = sectors_per_block - (sector_num % sectors_per_block);
- if (sectors > nb_sectors) {
- sectors = nb_sectors;
- }
+ if (offset == -1) {
+ offset = alloc_block(bs, sector_num , 0);
+ if (offset < 0) {
+ return -1;
+ }
+ }
- if (offset == -1) {
- offset = alloc_block(bs, sector_num);
- if (offset < 0)
+ ret = bdrv_pwrite(bs->file, offset, buf,
+ sectors * BDRV_SECTOR_SIZE);
+ if (ret != sectors * BDRV_SECTOR_SIZE) {
return -1;
- }
+ }
- ret = bdrv_pwrite(bs->file, offset, buf, sectors * BDRV_SECTOR_SIZE);
- if (ret != sectors * BDRV_SECTOR_SIZE) {
- return -1;
- }
+ nb_sectors -= sectors;
+ sector_num += sectors;
+ buf += sectors * BDRV_SECTOR_SIZE;
+ }
+ } else {
+ while (nb_sectors > 0) {
+ offset = get_sector_offset(bs, sector_num, 1);
+
+ sectors_per_block = s->block_size >> BDRV_SECTOR_BITS;
+ sectors = sectors_per_block - (sector_num % sectors_per_block);
+ if (sectors > nb_sectors) {
+ sectors = nb_sectors;
+ }
+
+ if (offset == -1) {
+ offset = alloc_block(bs, sector_num, 1);
+ if (offset < 0) {
+ return -1;
+ }
+ }
+
+ ret = bdrv_pwrite(bs->file, offset, buf,
+ sectors * BDRV_SECTOR_SIZE);
+ if (ret != sectors * BDRV_SECTOR_SIZE) {
+ return -1;
+ }
- nb_sectors -= sectors;
- sector_num += sectors;
- buf += sectors * BDRV_SECTOR_SIZE;
+ ret = write_bitmap(bs, sector_num, sectors);
+ if (ret < 0) {
+ return -1;
+ }
+
+ nb_sectors -= sectors;
+ sector_num += sectors;
+ buf += sectors * BDRV_SECTOR_SIZE;
+ }
}
return 0;
@@ -897,6 +1112,7 @@ static BlockDriver bdrv_vpc = {
.bdrv_close = vpc_close,
.bdrv_reopen_prepare = vpc_reopen_prepare,
.bdrv_create = vpc_create,
+ .supports_backing = true,
.bdrv_read = vpc_co_read,
.bdrv_write = vpc_co_write,
--
1.7.1