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