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Fix a race condition and non-leaf imagesgrowing in VMDK chains, by Igor

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Lvovsky.


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@2987 c046a42c-6fe2-441c-8c8c-71466251a162
This commit is contained in:
ths 2007-06-18 15:01:30 +00:00
parent e56869531a
commit 630530a652
1 changed files with 118 additions and 33 deletions
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151
block-vmdk.c
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@ -75,8 +75,25 @@ typedef struct BDRVVmdkState {
unsigned int cluster_sectors;
uint32_t parent_cid;
int is_parent;
} BDRVVmdkState;
typedef struct VmdkMetaData {
uint32_t offset;
unsigned int l1_index;
unsigned int l2_index;
unsigned int l2_offset;
int valid;
} VmdkMetaData;
typedef struct ActiveBDRVState{
BlockDriverState *hd; // active image handler
uint64_t cluster_offset; // current write offset
}ActiveBDRVState;
static ActiveBDRVState activeBDRV;
static int vmdk_probe(const uint8_t *buf, int buf_size, const char *filename)
{
uint32_t magic;
@ -305,7 +322,7 @@ static void vmdk_parent_close(BlockDriverState *bs)
bdrv_close(bs->backing_hd);
}
int parent_open = 0;
static int vmdk_parent_open(BlockDriverState *bs, const char * filename)
{
BDRVVmdkState *s = bs->opaque;
@ -339,8 +356,10 @@ static int vmdk_parent_open(BlockDriverState *bs, const char * filename)
bdrv_close(s->hd);
return -1;
}
if (bdrv_open(s->hd->backing_hd, parent_img_name, 0) < 0)
parent_open = 1;
if (bdrv_open(s->hd->backing_hd, parent_img_name, BDRV_O_RDONLY) < 0)
goto failure;
parent_open = 0;
}
return 0;
@ -352,6 +371,11 @@ static int vmdk_open(BlockDriverState *bs, const char *filename, int flags)
uint32_t magic;
int l1_size, i, ret;
if (parent_open)
// Parent must be opened as RO.
flags = BDRV_O_RDONLY;
fprintf(stderr, "(VMDK) image open: flags=0x%x filename=%s\n", flags, bs->filename);
ret = bdrv_file_open(&s->hd, filename, flags);
if (ret < 0)
return ret;
@ -387,6 +411,11 @@ static int vmdk_open(BlockDriverState *bs, const char *filename, int flags)
s->l1_table_offset = le64_to_cpu(header.rgd_offset) << 9;
s->l1_backup_table_offset = le64_to_cpu(header.gd_offset) << 9;
if (parent_open)
s->is_parent = 1;
else
s->is_parent = 0;
// try to open parent images, if exist
if (vmdk_parent_open(bs, filename) != 0)
goto fail;
@ -430,7 +459,8 @@ static int vmdk_open(BlockDriverState *bs, const char *filename, int flags)
return -1;
}
static uint64_t get_cluster_offset(BlockDriverState *bs, uint64_t offset, int allocate);
static uint64_t get_cluster_offset(BlockDriverState *bs, VmdkMetaData *m_data,
uint64_t offset, int allocate);
static int get_whole_cluster(BlockDriverState *bs, uint64_t cluster_offset,
uint64_t offset, int allocate)
@ -446,27 +476,55 @@ static int get_whole_cluster(BlockDriverState *bs, uint64_t cluster_offset,
if (!vmdk_is_cid_valid(bs))
return -1;
parent_cluster_offset = get_cluster_offset(s->hd->backing_hd, offset, allocate);
if (bdrv_pread(ps->hd, parent_cluster_offset, whole_grain, ps->cluster_sectors*512) !=
ps->cluster_sectors*512)
return -1;
if (bdrv_pwrite(s->hd, cluster_offset << 9, whole_grain, sizeof(whole_grain)) !=
sizeof(whole_grain))
return -1;
parent_cluster_offset = get_cluster_offset(s->hd->backing_hd, NULL, offset, allocate);
if (parent_cluster_offset) {
BDRVVmdkState *act_s = activeBDRV.hd->opaque;
if (bdrv_pread(ps->hd, parent_cluster_offset, whole_grain, ps->cluster_sectors*512) != ps->cluster_sectors*512)
return -1;
//Write grain only into the active image
if (bdrv_pwrite(act_s->hd, activeBDRV.cluster_offset << 9, whole_grain, sizeof(whole_grain)) != sizeof(whole_grain))
return -1;
}
}
return 0;
}
static uint64_t get_cluster_offset(BlockDriverState *bs,
static int vmdk_L2update(BlockDriverState *bs, VmdkMetaData *m_data)
{
BDRVVmdkState *s = bs->opaque;
/* update L2 table */
if (bdrv_pwrite(s->hd, ((int64_t)m_data->l2_offset * 512) + (m_data->l2_index * sizeof(m_data->offset)),
&(m_data->offset), sizeof(m_data->offset)) != sizeof(m_data->offset))
return -1;
/* update backup L2 table */
if (s->l1_backup_table_offset != 0) {
m_data->l2_offset = s->l1_backup_table[m_data->l1_index];
if (bdrv_pwrite(s->hd, ((int64_t)m_data->l2_offset * 512) + (m_data->l2_index * sizeof(m_data->offset)),
&(m_data->offset), sizeof(m_data->offset)) != sizeof(m_data->offset))
return -1;
}
return 0;
}
static uint64_t get_cluster_offset(BlockDriverState *bs, VmdkMetaData *m_data,
uint64_t offset, int allocate)
{
BDRVVmdkState *s = bs->opaque;
unsigned int l1_index, l2_offset, l2_index;
int min_index, i, j;
uint32_t min_count, *l2_table, tmp;
uint32_t min_count, *l2_table, tmp = 0;
uint64_t cluster_offset;
int status;
if (m_data)
m_data->valid = 0;
l1_index = (offset >> 9) / s->l1_entry_sectors;
if (l1_index >= s->l1_size)
return 0;
@ -504,32 +562,45 @@ static uint64_t get_cluster_offset(BlockDriverState *bs,
found:
l2_index = ((offset >> 9) / s->cluster_sectors) % s->l2_size;
cluster_offset = le32_to_cpu(l2_table[l2_index]);
if (!cluster_offset) {
struct stat file_buf;
if (!allocate)
return 0;
stat(s->hd->filename, &file_buf);
cluster_offset = file_buf.st_size;
bdrv_truncate(s->hd, cluster_offset + (s->cluster_sectors << 9));
cluster_offset >>= 9;
/* update L2 table */
tmp = cpu_to_le32(cluster_offset);
l2_table[l2_index] = tmp;
if (bdrv_pwrite(s->hd, ((int64_t)l2_offset * 512) + (l2_index * sizeof(tmp)),
&tmp, sizeof(tmp)) != sizeof(tmp))
return 0;
/* update backup L2 table */
if (s->l1_backup_table_offset != 0) {
l2_offset = s->l1_backup_table[l1_index];
if (bdrv_pwrite(s->hd, ((int64_t)l2_offset * 512) + (l2_index * sizeof(tmp)),
&tmp, sizeof(tmp)) != sizeof(tmp))
// Avoid the L2 tables update for the images that have snapshots.
if (!s->is_parent) {
status = stat(s->hd->filename, &file_buf);
if (status == -1) {
fprintf(stderr, "(VMDK) Fail file stat: filename =%s size=0x%lx errno=%s\n",
s->hd->filename, (uint64_t)file_buf.st_size, strerror(errno));
return 0;
}
}
cluster_offset = file_buf.st_size;
bdrv_truncate(s->hd, cluster_offset + (s->cluster_sectors << 9));
cluster_offset >>= 9;
tmp = cpu_to_le32(cluster_offset);
l2_table[l2_index] = tmp;
// Save the active image state
activeBDRV.cluster_offset = cluster_offset;
activeBDRV.hd = bs;
}
/* First of all we write grain itself, to avoid race condition
* that may to corrupt the image.
* This problem may occur because of insufficient space on host disk
* or inappropriate VM shutdown.
*/
if (get_whole_cluster(bs, cluster_offset, offset, allocate) == -1)
return 0;
if (m_data) {
m_data->offset = tmp;
m_data->l1_index = l1_index;
m_data->l2_index = l2_index;
m_data->l2_offset = l2_offset;
m_data->valid = 1;
}
}
cluster_offset <<= 9;
return cluster_offset;
@ -542,7 +613,7 @@ static int vmdk_is_allocated(BlockDriverState *bs, int64_t sector_num,
int index_in_cluster, n;
uint64_t cluster_offset;
cluster_offset = get_cluster_offset(bs, sector_num << 9, 0);
cluster_offset = get_cluster_offset(bs, NULL, sector_num << 9, 0);
index_in_cluster = sector_num % s->cluster_sectors;
n = s->cluster_sectors - index_in_cluster;
if (n > nb_sectors)
@ -559,7 +630,7 @@ static int vmdk_read(BlockDriverState *bs, int64_t sector_num,
uint64_t cluster_offset;
while (nb_sectors > 0) {
cluster_offset = get_cluster_offset(bs, sector_num << 9, 0);
cluster_offset = get_cluster_offset(bs, NULL, sector_num << 9, 0);
index_in_cluster = sector_num % s->cluster_sectors;
n = s->cluster_sectors - index_in_cluster;
if (n > nb_sectors)
@ -590,20 +661,34 @@ static int vmdk_write(BlockDriverState *bs, int64_t sector_num,
const uint8_t *buf, int nb_sectors)
{
BDRVVmdkState *s = bs->opaque;
VmdkMetaData m_data;
int index_in_cluster, n;
uint64_t cluster_offset;
static int cid_update = 0;
if (sector_num > bs->total_sectors) {
fprintf(stderr,
"(VMDK) Wrong offset: sector_num=0x%lx total_sectors=0x%lx\n",
sector_num, bs->total_sectors);
return -1;
}
while (nb_sectors > 0) {
index_in_cluster = sector_num & (s->cluster_sectors - 1);
n = s->cluster_sectors - index_in_cluster;
if (n > nb_sectors)
n = nb_sectors;
cluster_offset = get_cluster_offset(bs, sector_num << 9, 1);
cluster_offset = get_cluster_offset(bs, &m_data, sector_num << 9, 1);
if (!cluster_offset)
return -1;
if (bdrv_pwrite(s->hd, cluster_offset + index_in_cluster * 512, buf, n * 512) != n * 512)
return -1;
if (m_data.valid) {
/* update L2 tables */
if (vmdk_L2update(bs, &m_data) == -1)
return -1;
}
nb_sectors -= n;
sector_num += n;
buf += n * 512;