Message ID | 1318436596-6952-1-git-send-email-wdongxu@linux.vnet.ibm.com |
---|---|
State | New |
Headers | show |
On Thu 13 Oct 2011 12:23:16 AM CST, Dong Xu Wang wrote: > Add add-cow file format > > Signed-off-by: Dong Xu Wang<wdongxu@linux.vnet.ibm.com> > --- > Makefile.objs | 1 + > block.c | 2 +- > block.h | 1 + > block/add-cow.c | 412 ++++++++++++++++++++++++++++++++++++++++++++++++ > block_int.h | 1 + > docs/specs/add-cow.txt | 45 ++++++ > 6 files changed, 461 insertions(+), 1 deletions(-) > create mode 100644 block/add-cow.c > create mode 100644 docs/specs/add-cow.txt > > diff --git a/Makefile.objs b/Makefile.objs > index c849e51..624c04c 100644 > --- a/Makefile.objs > +++ b/Makefile.objs > @@ -31,6 +31,7 @@ block-obj-$(CONFIG_LINUX_AIO) += linux-aio.o > > block-nested-y += raw.o cow.o qcow.o vdi.o vmdk.o cloop.o dmg.o bochs.o vpc.o vvfat.o > block-nested-y += qcow2.o qcow2-refcount.o qcow2-cluster.o qcow2-snapshot.o qcow2-cache.o > +block-nested-y += add-cow.o > block-nested-y += qed.o qed-gencb.o qed-l2-cache.o qed-table.o qed-cluster.o > block-nested-y += qed-check.o > block-nested-y += parallels.o nbd.o blkdebug.o sheepdog.o blkverify.o > diff --git a/block.c b/block.c > index e865fab..c25241d 100644 > --- a/block.c > +++ b/block.c > @@ -106,7 +106,7 @@ int is_windows_drive(const char *filename) > #endif > > /* check if the path starts with "<protocol>:" */ > -static int path_has_protocol(const char *path) > +int path_has_protocol(const char *path) > { > #ifdef _WIN32 > if (is_windows_drive(path) || > diff --git a/block.h b/block.h > index 16bfa0a..8b09f12 100644 > --- a/block.h > +++ b/block.h > @@ -256,6 +256,7 @@ char *bdrv_snapshot_dump(char *buf, int buf_size, QEMUSnapshotInfo *sn); > > char *get_human_readable_size(char *buf, int buf_size, int64_t size); > int path_is_absolute(const char *path); > +int path_has_protocol(const char *path); > void path_combine(char *dest, int dest_size, > const char *base_path, > const char *filename); > diff --git a/block/add-cow.c b/block/add-cow.c > new file mode 100644 > index 0000000..d2538a2 > --- /dev/null > +++ b/block/add-cow.c > @@ -0,0 +1,412 @@ > +#include "qemu-common.h" > +#include "block_int.h" > +#include "module.h" > + > +#define ADD_COW_MAGIC (((uint64_t)'A'<< 56) | ((uint64_t)'D'<< 48) | \ > + ((uint64_t)'D'<< 40) | ((uint64_t)'_'<< 32) | \ > + ((uint64_t)'C'<< 24) | ((uint64_t)'O'<< 16) | \ > + ((uint64_t)'W'<< 8) | 0xFF) > +#define ADD_COW_VERSION 1 > + > +typedef struct AddCowHeader { > + uint64_t magic; > + uint32_t version; > + char backing_file[1024]; > + char image_file[1024]; > + uint64_t size; > +} QEMU_PACKED AddCowHeader; > + > +typedef struct BDRVAddCowState { > + char image_file[1024]; > + BlockDriverState *image_hd; > + uint8_t *bitmap; > + uint64_t bitmap_size; > +} BDRVAddCowState; > + > +static int add_cow_probe(const uint8_t *buf, int buf_size, const char *filename) > +{ > + const AddCowHeader *header = (const void *)buf; > + > + if (be64_to_cpu(header->magic) == ADD_COW_MAGIC&& > + be32_to_cpu(header->version) == ADD_COW_VERSION) { > + return 100; > + } else { > + return 0; > + } > +} > + > +static int add_cow_open(BlockDriverState *bs, int flags) > +{ > + AddCowHeader header; > + int64_t size; > + char image_filename[1024]; > + int image_flags; > + BlockDriver *image_drv = NULL; > + int ret; > + BDRVAddCowState *state = (BDRVAddCowState *)(bs->opaque); > + > + ret = bdrv_pread(bs->file, 0,&header, sizeof(header)); > + if (ret != sizeof(header)) { > + goto fail; > + } > + > + if (be64_to_cpu(header.magic) != ADD_COW_MAGIC || > + be32_to_cpu(header.version) != ADD_COW_VERSION) { > + ret = -1; > + goto fail; > + } > + > + size = be64_to_cpu(header.size); > + bs->total_sectors = size / BDRV_SECTOR_SIZE; > + > + QEMU_BUILD_BUG_ON(sizeof(state->image_file) != sizeof(header.image_file)); > + pstrcpy(bs->backing_file, sizeof(bs->backing_file), > + header.backing_file); > + pstrcpy(state->image_file, sizeof(state->image_file), > + header.image_file); > + > + state->bitmap_size = ((bs->total_sectors + 7)>> 3); > + state->bitmap = g_malloc0(state->bitmap_size); > + > + ret = bdrv_pread(bs->file, sizeof(header), state->bitmap, > + state->bitmap_size); > + if (ret != state->bitmap_size) { > + goto fail; > + } > + /* If there is a image_file, must be together with backing_file */ > + if (state->image_file[0] != '\0') { > + state->image_hd = bdrv_new(""); > + /* Relative to image or working dir, need discussion */ > + if (path_has_protocol(state->image_file)) { > + pstrcpy(image_filename, sizeof(image_filename), > + state->image_file); > + } else { > + path_combine(image_filename, sizeof(image_filename), > + bs->filename, state->image_file); > + } > + > + image_drv = bdrv_find_format("raw"); > + image_flags = > + (flags& (~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING))) | BDRV_O_RDWR; > + state->image_hd->keep_read_only = 0; > + > + ret = bdrv_open(state->image_hd, image_filename, image_flags, > + image_drv); > + if (ret< 0) { > + goto fail; > + } > + } else { > + ret = -ENOENT; > + goto fail; > + } > + return 0; > + fail: > + if (state->bitmap) { > + g_free(state->bitmap); > + state->bitmap = NULL; > + } > + return ret; > +} > + > +static inline void add_cow_set_bit(BlockDriverState *bs, int64_t bitnum) > +{ > + uint64_t offset = bitnum / 8; > + BDRVAddCowState *state = (BDRVAddCowState *)(bs->opaque); > + state->bitmap[offset] |= (1<< (bitnum % 8)); > +} > + > +static inline int is_bit_set(BlockDriverState *bs, int64_t bitnum) > +{ > + BDRVAddCowState *state = (BDRVAddCowState *)(bs->opaque); > + uint64_t offset = bitnum / 8; > + return !!(state->bitmap[offset]& (1<< (bitnum % 8))); > +} > + > +static int add_cow_is_allocated(BlockDriverState *bs, int64_t sector_num, > + int nb_sectors, int *num_same) > +{ > + int changed; > + uint64_t bitmap_size = ((BDRVAddCowState *)(bs->opaque))->bitmap_size; > + > + /* Beyond the end of bitmap, return error or read from backing_file? */ > + if (((sector_num + nb_sectors + 7) / 8)> bitmap_size) { > + return 0; > + } > + > + if (nb_sectors == 0) { > + *num_same = nb_sectors; > + return 0; > + } > + > + changed = is_bit_set(bs, sector_num); > + if (changed< 0) { > + return 0; > + } > + > + for (*num_same = 1; *num_same< nb_sectors; (*num_same)++) { > + if (is_bit_set(bs, sector_num + *num_same) != changed) { > + break; > + } > + } > + > + return changed; > +} > + > +static int add_cow_update_bitmap(BlockDriverState *bs, int64_t sector_num, > + int nb_sectors) > +{ > + int i, ret = 0; > + BDRVAddCowState *state = (BDRVAddCowState *)(bs->opaque); > + uint64_t start_pos = sector_num / 8; > + uint64_t end_pos = (sector_num + nb_sectors - 1) / 8; > + > + if (start_pos> state->bitmap_size) { > + return -1; > + } > + > + for (i = 0; i< nb_sectors; i++) { > + add_cow_set_bit(bs, sector_num + i); > + } > + ret = bdrv_pwrite_sync(bs->file, > + sizeof(AddCowHeader) + start_pos, > + state->bitmap + start_pos, > + MIN(((end_pos - start_pos)& (~512)) + 512, state->bitmap_size - start_pos)); > + return ret; > +} > + > +static void add_cow_close(BlockDriverState *bs) > +{ > + BDRVAddCowState *state = (BDRVAddCowState *)(bs->opaque); > + if (state->bitmap) { > + g_free(state->bitmap); > + state->bitmap = NULL; > + } > +} > + > +static int add_cow_create(const char *filename, QEMUOptionParameter *options) > +{ > + AddCowHeader header; > + int64_t image_sectors = 0; > + const char *backing_filename = NULL; > + const char *image_filename = NULL; > + int ret; > + BlockDriverState *bs, *image_bs = NULL; > + > + while (options&& options->name) { > + if (!strcmp(options->name, BLOCK_OPT_SIZE)) { > + image_sectors = options->value.n / BDRV_SECTOR_SIZE; > + } else if (!strcmp(options->name, BLOCK_OPT_BACKING_FILE)) { > + backing_filename = options->value.s; > + } else if (!strcmp(options->name, BLOCK_OPT_IMAGE_FILE)) { > + image_filename = options->value.s; > + } > + options++; > + } > + > + if (!backing_filename || !image_filename) { > + return -EINVAL; > + } > + /* Make sure image file exists */ > + ret = bdrv_file_open(&image_bs, image_filename, BDRV_O_RDWR > + | BDRV_O_CACHE_WB); > + if (ret< 0) { > + return ret; > + } > + bdrv_close(image_bs); > + ret = bdrv_create_file(filename, NULL); > + if (ret< 0) { > + return ret; > + } > + > + ret = bdrv_file_open(&bs, filename, BDRV_O_RDWR); > + if (ret< 0) { > + return ret; > + } > + > + memset(&header, 0, sizeof(header)); > + header.magic = cpu_to_be64(ADD_COW_MAGIC); > + header.version = cpu_to_be32(ADD_COW_VERSION); > + pstrcpy(header.backing_file, sizeof(header.backing_file), backing_filename); > + pstrcpy(header.image_file, sizeof(header.image_file), image_filename); > + header.size = cpu_to_be64(image_sectors * BDRV_SECTOR_SIZE); > + > + ret = bdrv_pwrite(bs, 0,&header, sizeof(header)); > + if (ret< 0) { > + bdrv_close(bs); > + return ret; > + } > + bdrv_close(bs); > + > + BlockDriver *drv = bdrv_find_format("add-cow"); > + assert(drv != NULL); > + ret = bdrv_open(bs, filename, BDRV_O_RDWR | BDRV_O_NO_FLUSH, drv); > + if (ret< 0) { > + return ret; > + } > + > + ret = bdrv_truncate(bs, image_sectors * BDRV_SECTOR_SIZE); > +fail: Sorry, "fail" label is not used. While testing, after apply the patch, please delete this line. The patch has too many lines, so I did not re-send the new one. > + bdrv_close(bs); > + return ret; > +} > + > +static int add_cow_co_readv(BlockDriverState *bs, int64_t sector_num, > + int remaining_sectors, QEMUIOVector *qiov) > +{ > + BDRVAddCowState *s = bs->opaque; > + int cur_nr_sectors; > + uint64_t bytes_done = 0; > + QEMUIOVector hd_qiov; > + int n, ret = 0; > + > + qemu_iovec_init(&hd_qiov, qiov->niov); > + while (remaining_sectors != 0) { > + cur_nr_sectors = remaining_sectors; > + if (add_cow_is_allocated(bs, sector_num, cur_nr_sectors,&n)) { > + cur_nr_sectors = n; > + qemu_iovec_reset(&hd_qiov); > + qemu_iovec_copy(&hd_qiov, qiov, bytes_done, > + cur_nr_sectors * BDRV_SECTOR_SIZE); > + ret = bdrv_co_readv(s->image_hd, sector_num, n,&hd_qiov); > + if (ret< 0) { > + goto fail; > + } > + } else { > + cur_nr_sectors = n; > + if (bs->backing_hd) { > + qemu_iovec_reset(&hd_qiov); > + qemu_iovec_copy(&hd_qiov, qiov, bytes_done, > + cur_nr_sectors * BDRV_SECTOR_SIZE); > + ret = bdrv_co_readv(bs->backing_hd, sector_num, > + n,&hd_qiov); > + if (ret< 0) { > + goto fail; > + } > + } else { > + qemu_iovec_reset(&hd_qiov); > + qemu_iovec_memset(&hd_qiov, 0, > + BDRV_SECTOR_SIZE * cur_nr_sectors); > + } > + } > + remaining_sectors -= cur_nr_sectors; > + sector_num += cur_nr_sectors; > + bytes_done += cur_nr_sectors * BDRV_SECTOR_SIZE; > + } > +fail: > + qemu_iovec_destroy(&hd_qiov); > + return ret; > +} > + > +static int add_cow_co_writev(BlockDriverState *bs, int64_t sector_num, > + int remaining_sectors, QEMUIOVector *qiov) > +{ > + BDRVAddCowState *s = bs->opaque; > + int ret = 0; > + QEMUIOVector hd_qiov; > + qemu_iovec_init(&hd_qiov, qiov->niov); > + > + qemu_iovec_reset(&hd_qiov); > + qemu_iovec_copy(&hd_qiov, qiov, 0, remaining_sectors * BDRV_SECTOR_SIZE); > + ret = bdrv_co_writev(s->image_hd, > + sector_num, > + remaining_sectors,&hd_qiov); > + if (ret< 0) { > + goto fail; > + } > + > + ret = add_cow_update_bitmap(bs, sector_num, remaining_sectors); > + if (ret< 0) { > + goto fail; > + } > +fail: > + qemu_iovec_destroy(&hd_qiov); > + return ret; > +} > + > +static int bdrv_add_cow_truncate(BlockDriverState *bs, int64_t offset) > +{ > + int ret = 0; > + int64_t image_sectors = offset/BDRV_SECTOR_SIZE; > + int64_t be_offset = cpu_to_be64(offset); > + BDRVAddCowState *state = bs->opaque; > + ret = bdrv_truncate(bs->file, ((image_sectors + 7)>> 3) > + + sizeof(AddCowHeader)); > + if (ret< 0) { > + return ret; > + } > + > + ret = bdrv_pwrite_sync(bs->file, offsetof(AddCowHeader, size), > +&be_offset, sizeof(uint64_t)); > + if (ret< 0) { > + return ret; > + } > + > + ret = bdrv_truncate(state->image_hd, offset); > + return ret; > +} > + > +static QEMUOptionParameter add_cow_create_options[] = { > + { > + .name = BLOCK_OPT_SIZE, > + .type = OPT_SIZE, > + .help = "Virtual disk size" > + }, > + { > + .name = BLOCK_OPT_BACKING_FILE, > + .type = OPT_STRING, > + .help = "File name of a base image" > + }, > + { > + .name = BLOCK_OPT_IMAGE_FILE, > + .type = OPT_STRING, > + .help = "File name of a image file" > + }, > + { NULL } > +}; > + > +static int add_cow_flush(BlockDriverState *bs) > +{ > + BDRVAddCowState *state = bs->opaque; > + int ret = bdrv_flush(state->image_hd); > + if (ret< 0) { > + return ret; > + } > + return bdrv_flush(bs->file); > +} > + > +static BlockDriverAIOCB *add_cow_aio_flush(BlockDriverState *bs, > + BlockDriverCompletionFunc *cb, void *opaque) > +{ > + BDRVAddCowState *state = bs->opaque; > + int ret = bdrv_flush(state->image_hd); > + if (ret< 0) { > + return NULL; > + } > + > + return bdrv_aio_flush(bs->file, cb, opaque); > +} > + > +static BlockDriver bdrv_add_cow = { > + .format_name = "add-cow", > + .instance_size = sizeof(BDRVAddCowState), > + .bdrv_probe = add_cow_probe, > + .bdrv_open = add_cow_open, > + .bdrv_close = add_cow_close, > + .bdrv_create = add_cow_create, > + .bdrv_is_allocated = add_cow_is_allocated, > + > + .bdrv_co_readv = add_cow_co_readv, > + .bdrv_co_writev = add_cow_co_writev, > + .bdrv_truncate = bdrv_add_cow_truncate, > + > + .create_options = add_cow_create_options, > + .bdrv_flush = add_cow_flush, > + .bdrv_aio_flush = add_cow_aio_flush, > +}; > + > +static void bdrv_add_cow_init(void) > +{ > + bdrv_register(&bdrv_add_cow); > +} > + > +block_init(bdrv_add_cow_init); > diff --git a/block_int.h b/block_int.h > index 8c3b863..2b26fdc 100644 > --- a/block_int.h > +++ b/block_int.h > @@ -42,6 +42,7 @@ > #define BLOCK_OPT_TABLE_SIZE "table_size" > #define BLOCK_OPT_PREALLOC "preallocation" > #define BLOCK_OPT_SUBFMT "subformat" > +#define BLOCK_OPT_IMAGE_FILE "image_file" > > typedef struct AIOPool { > void (*cancel)(BlockDriverAIOCB *acb); > diff --git a/docs/specs/add-cow.txt b/docs/specs/add-cow.txt > new file mode 100644 > index 0000000..0443c6c > --- /dev/null > +++ b/docs/specs/add-cow.txt > @@ -0,0 +1,45 @@ > +== General == > + > +Raw file format does not support backing_file and copy on write feature. Then > +you can use add-cow file realize these features. > + > +When using add-cow, procedures may like this: > +(ubuntu.img is a disk image which has been installed OS.) > + 1) Create a raw image with the same size of ubuntu.img > + qemu-img create -f raw test.raw 8G > + 2) Create a add-cow image which will store dirty bitmap > + qemu-img create -f add-cow test.add-cow -o backing_file=ubuntu.img,image_file=test.raw > + 3) Run qemu with add-cow image > + qemu -drive if=virtio,file=test.add-cow > + > +=Specification= > + > +The file format looks like this: > + > + +----------+----------+----------+-----+ > + | Header | Data | Data | ... | > + +----------+----------+----------+-----+ > + > + All numbers in add-cow are stored in Big Endian byte order. > + > + > +== Header == > + > +The Header is included in the first bytes: > + > + Byte 0 - 7: magic > + add-cow magic string ("ADD_COW\xff") > + > + 8 - 11: version > + Version number (only valid value is 1 now) > + > + 12 - 1035: backing_file > + backing_file file name related to add-cow file. While > + using backing_file, must together with image_file. > + > + 1036 - 2059: image_file > + image_file is a raw file, While using image_file, must > + together with image_file. > + > + 2060 - 2067: size > + Virtual disk size of image_file in bytes.
On 2011-10-13 0:23, Dong Xu Wang wrote: > Add add-cow file format > > Signed-off-by: Dong Xu Wang<wdongxu@linux.vnet.ibm.com> > --- > Makefile.objs | 1 + > block.c | 2 +- > block.h | 1 + > block/add-cow.c | 412 ++++++++++++++++++++++++++++++++++++++++++++++++ > block_int.h | 1 + > docs/specs/add-cow.txt | 45 ++++++ > 6 files changed, 461 insertions(+), 1 deletions(-) > create mode 100644 block/add-cow.c > create mode 100644 docs/specs/add-cow.txt > > diff --git a/Makefile.objs b/Makefile.objs > index c849e51..624c04c 100644 > --- a/Makefile.objs > +++ b/Makefile.objs > @@ -31,6 +31,7 @@ block-obj-$(CONFIG_LINUX_AIO) += linux-aio.o > > block-nested-y += raw.o cow.o qcow.o vdi.o vmdk.o cloop.o dmg.o bochs.o vpc.o vvfat.o > block-nested-y += qcow2.o qcow2-refcount.o qcow2-cluster.o qcow2-snapshot.o qcow2-cache.o > +block-nested-y += add-cow.o > block-nested-y += qed.o qed-gencb.o qed-l2-cache.o qed-table.o qed-cluster.o > block-nested-y += qed-check.o > block-nested-y += parallels.o nbd.o blkdebug.o sheepdog.o blkverify.o > diff --git a/block.c b/block.c > index e865fab..c25241d 100644 > --- a/block.c > +++ b/block.c > @@ -106,7 +106,7 @@ int is_windows_drive(const char *filename) > #endif > > /* check if the path starts with "<protocol>:" */ > -static int path_has_protocol(const char *path) > +int path_has_protocol(const char *path) > { > #ifdef _WIN32 > if (is_windows_drive(path) || > diff --git a/block.h b/block.h > index 16bfa0a..8b09f12 100644 > --- a/block.h > +++ b/block.h > @@ -256,6 +256,7 @@ char *bdrv_snapshot_dump(char *buf, int buf_size, QEMUSnapshotInfo *sn); > > char *get_human_readable_size(char *buf, int buf_size, int64_t size); > int path_is_absolute(const char *path); > +int path_has_protocol(const char *path); > void path_combine(char *dest, int dest_size, > const char *base_path, > const char *filename); > diff --git a/block/add-cow.c b/block/add-cow.c > new file mode 100644 > index 0000000..d2538a2 > --- /dev/null > +++ b/block/add-cow.c > @@ -0,0 +1,412 @@ > +#include "qemu-common.h" > +#include "block_int.h" > +#include "module.h" > + > +#define ADD_COW_MAGIC (((uint64_t)'A'<< 56) | ((uint64_t)'D'<< 48) | \ > + ((uint64_t)'D'<< 40) | ((uint64_t)'_'<< 32) | \ > + ((uint64_t)'C'<< 24) | ((uint64_t)'O'<< 16) | \ > + ((uint64_t)'W'<< 8) | 0xFF) > +#define ADD_COW_VERSION 1 > + > +typedef struct AddCowHeader { > + uint64_t magic; > + uint32_t version; > + char backing_file[1024]; > + char image_file[1024]; 1024 is a magic number for me. Can we have a meaningful macro? > + uint64_t size; > +} QEMU_PACKED AddCowHeader; > + > +typedef struct BDRVAddCowState { > + char image_file[1024]; > + BlockDriverState *image_hd; > + uint8_t *bitmap; > + uint64_t bitmap_size; > +} BDRVAddCowState; > + > +static int add_cow_probe(const uint8_t *buf, int buf_size, const char *filename) > +{ > + const AddCowHeader *header = (const void *)buf; > + > + if (be64_to_cpu(header->magic) == ADD_COW_MAGIC&& > + be32_to_cpu(header->version) == ADD_COW_VERSION) { > + return 100; > + } else { > + return 0; > + } > +} > + > +static int add_cow_open(BlockDriverState *bs, int flags) > +{ > + AddCowHeader header; > + int64_t size; > + char image_filename[1024]; > + int image_flags; > + BlockDriver *image_drv = NULL; > + int ret; > + BDRVAddCowState *state = (BDRVAddCowState *)(bs->opaque); > + > + ret = bdrv_pread(bs->file, 0,&header, sizeof(header)); > + if (ret != sizeof(header)) { > + goto fail; > + } > + > + if (be64_to_cpu(header.magic) != ADD_COW_MAGIC || > + be32_to_cpu(header.version) != ADD_COW_VERSION) { > + ret = -1; > + goto fail; > + } > + > + size = be64_to_cpu(header.size); > + bs->total_sectors = size / BDRV_SECTOR_SIZE; > + > + QEMU_BUILD_BUG_ON(sizeof(state->image_file) != sizeof(header.image_file)); > + pstrcpy(bs->backing_file, sizeof(bs->backing_file), > + header.backing_file); > + pstrcpy(state->image_file, sizeof(state->image_file), > + header.image_file); > + > + state->bitmap_size = ((bs->total_sectors + 7)>> 3); > + state->bitmap = g_malloc0(state->bitmap_size); > + > + ret = bdrv_pread(bs->file, sizeof(header), state->bitmap, > + state->bitmap_size); > + if (ret != state->bitmap_size) { > + goto fail; > + } > + /* If there is a image_file, must be together with backing_file */ > + if (state->image_file[0] != '\0') { > + state->image_hd = bdrv_new(""); > + /* Relative to image or working dir, need discussion */ > + if (path_has_protocol(state->image_file)) { > + pstrcpy(image_filename, sizeof(image_filename), > + state->image_file); > + } else { > + path_combine(image_filename, sizeof(image_filename), > + bs->filename, state->image_file); > + } > + > + image_drv = bdrv_find_format("raw"); > + image_flags = > + (flags& (~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING))) | BDRV_O_RDWR; > + state->image_hd->keep_read_only = 0; > + > + ret = bdrv_open(state->image_hd, image_filename, image_flags, > + image_drv); > + if (ret< 0) { > + goto fail; > + } > + } else { > + ret = -ENOENT; > + goto fail; > + } > + return 0; > + fail: > + if (state->bitmap) { > + g_free(state->bitmap); > + state->bitmap = NULL; > + } > + return ret; > +} > + > +static inline void add_cow_set_bit(BlockDriverState *bs, int64_t bitnum) > +{ > + uint64_t offset = bitnum / 8; > + BDRVAddCowState *state = (BDRVAddCowState *)(bs->opaque); > + state->bitmap[offset] |= (1<< (bitnum % 8)); > +} > + > +static inline int is_bit_set(BlockDriverState *bs, int64_t bitnum) > +{ > + BDRVAddCowState *state = (BDRVAddCowState *)(bs->opaque); > + uint64_t offset = bitnum / 8; > + return !!(state->bitmap[offset]& (1<< (bitnum % 8))); > +} > + > +static int add_cow_is_allocated(BlockDriverState *bs, int64_t sector_num, > + int nb_sectors, int *num_same) > +{ > + int changed; > + uint64_t bitmap_size = ((BDRVAddCowState *)(bs->opaque))->bitmap_size; > + > + /* Beyond the end of bitmap, return error or read from backing_file? */ > + if (((sector_num + nb_sectors + 7) / 8)> bitmap_size) { > + return 0; > + } > + > + if (nb_sectors == 0) { > + *num_same = nb_sectors; > + return 0; > + } > + > + changed = is_bit_set(bs, sector_num); > + if (changed< 0) { > + return 0; > + } > + > + for (*num_same = 1; *num_same< nb_sectors; (*num_same)++) { > + if (is_bit_set(bs, sector_num + *num_same) != changed) { > + break; > + } > + } > + > + return changed; > +} > + > +static int add_cow_update_bitmap(BlockDriverState *bs, int64_t sector_num, > + int nb_sectors) > +{ > + int i, ret = 0; > + BDRVAddCowState *state = (BDRVAddCowState *)(bs->opaque); > + uint64_t start_pos = sector_num / 8; > + uint64_t end_pos = (sector_num + nb_sectors - 1) / 8; > + > + if (start_pos> state->bitmap_size) { > + return -1; > + } > + > + for (i = 0; i< nb_sectors; i++) { > + add_cow_set_bit(bs, sector_num + i); > + } > + ret = bdrv_pwrite_sync(bs->file, > + sizeof(AddCowHeader) + start_pos, > + state->bitmap + start_pos, > + MIN(((end_pos - start_pos)& (~512)) + 512, state->bitmap_size - start_pos)); > + return ret; > +} > + > +static void add_cow_close(BlockDriverState *bs) > +{ > + BDRVAddCowState *state = (BDRVAddCowState *)(bs->opaque); > + if (state->bitmap) { > + g_free(state->bitmap); > + state->bitmap = NULL; > + } > +} > + > +static int add_cow_create(const char *filename, QEMUOptionParameter *options) > +{ > + AddCowHeader header; > + int64_t image_sectors = 0; > + const char *backing_filename = NULL; > + const char *image_filename = NULL; > + int ret; > + BlockDriverState *bs, *image_bs = NULL; > + > + while (options&& options->name) { > + if (!strcmp(options->name, BLOCK_OPT_SIZE)) { > + image_sectors = options->value.n / BDRV_SECTOR_SIZE; > + } else if (!strcmp(options->name, BLOCK_OPT_BACKING_FILE)) { > + backing_filename = options->value.s; > + } else if (!strcmp(options->name, BLOCK_OPT_IMAGE_FILE)) { > + image_filename = options->value.s; > + } > + options++; > + } > + > + if (!backing_filename || !image_filename) { > + return -EINVAL; > + } > + /* Make sure image file exists */ > + ret = bdrv_file_open(&image_bs, image_filename, BDRV_O_RDWR > + | BDRV_O_CACHE_WB); > + if (ret< 0) { > + return ret; > + } > + bdrv_close(image_bs); > + ret = bdrv_create_file(filename, NULL); > + if (ret< 0) { > + return ret; > + } > + > + ret = bdrv_file_open(&bs, filename, BDRV_O_RDWR); > + if (ret< 0) { > + return ret; > + } > + > + memset(&header, 0, sizeof(header)); > + header.magic = cpu_to_be64(ADD_COW_MAGIC); > + header.version = cpu_to_be32(ADD_COW_VERSION); > + pstrcpy(header.backing_file, sizeof(header.backing_file), backing_filename); > + pstrcpy(header.image_file, sizeof(header.image_file), image_filename); > + header.size = cpu_to_be64(image_sectors * BDRV_SECTOR_SIZE); > + > + ret = bdrv_pwrite(bs, 0,&header, sizeof(header)); > + if (ret< 0) { > + bdrv_close(bs); > + return ret; > + } > + bdrv_close(bs); > + > + BlockDriver *drv = bdrv_find_format("add-cow"); > + assert(drv != NULL); > + ret = bdrv_open(bs, filename, BDRV_O_RDWR | BDRV_O_NO_FLUSH, drv); > + if (ret< 0) { > + return ret; > + } > + > + ret = bdrv_truncate(bs, image_sectors * BDRV_SECTOR_SIZE); > +fail: "fail" label is not used in this function. > + bdrv_close(bs); > + return ret; > +} > + > +static int add_cow_co_readv(BlockDriverState *bs, int64_t sector_num, > + int remaining_sectors, QEMUIOVector *qiov) > +{ > + BDRVAddCowState *s = bs->opaque; > + int cur_nr_sectors; > + uint64_t bytes_done = 0; > + QEMUIOVector hd_qiov; > + int n, ret = 0; > + > + qemu_iovec_init(&hd_qiov, qiov->niov); > + while (remaining_sectors != 0) { > + cur_nr_sectors = remaining_sectors; > + if (add_cow_is_allocated(bs, sector_num, cur_nr_sectors,&n)) { > + cur_nr_sectors = n; > + qemu_iovec_reset(&hd_qiov); > + qemu_iovec_copy(&hd_qiov, qiov, bytes_done, > + cur_nr_sectors * BDRV_SECTOR_SIZE); > + ret = bdrv_co_readv(s->image_hd, sector_num, n,&hd_qiov); > + if (ret< 0) { > + goto fail; > + } > + } else { > + cur_nr_sectors = n; > + if (bs->backing_hd) { > + qemu_iovec_reset(&hd_qiov); > + qemu_iovec_copy(&hd_qiov, qiov, bytes_done, > + cur_nr_sectors * BDRV_SECTOR_SIZE); > + ret = bdrv_co_readv(bs->backing_hd, sector_num, > + n,&hd_qiov); > + if (ret< 0) { > + goto fail; > + } > + } else { > + qemu_iovec_reset(&hd_qiov); > + qemu_iovec_memset(&hd_qiov, 0, > + BDRV_SECTOR_SIZE * cur_nr_sectors); > + } > + } > + remaining_sectors -= cur_nr_sectors; > + sector_num += cur_nr_sectors; > + bytes_done += cur_nr_sectors * BDRV_SECTOR_SIZE; > + } > +fail: > + qemu_iovec_destroy(&hd_qiov); > + return ret; > +} > + > +static int add_cow_co_writev(BlockDriverState *bs, int64_t sector_num, > + int remaining_sectors, QEMUIOVector *qiov) > +{ > + BDRVAddCowState *s = bs->opaque; > + int ret = 0; > + QEMUIOVector hd_qiov; > + qemu_iovec_init(&hd_qiov, qiov->niov); > + It looks like that the memory where "bs" is pointing to should be protected by a lock. Because "bs" was passed to several BlockDriver entries like ".bdrv_co_writev', 'bdrv_co_readv'&etc which can be executed in parallel to access the memory where "bs" is pointing to. > + qemu_iovec_reset(&hd_qiov); > + qemu_iovec_copy(&hd_qiov, qiov, 0, remaining_sectors * BDRV_SECTOR_SIZE); > + ret = bdrv_co_writev(s->image_hd, > + sector_num, > + remaining_sectors,&hd_qiov); > + if (ret< 0) { > + goto fail; > + } > + > + ret = add_cow_update_bitmap(bs, sector_num, remaining_sectors); > + if (ret< 0) { > + goto fail; > + } > +fail: > + qemu_iovec_destroy(&hd_qiov); > + return ret; > +} > + > +static int bdrv_add_cow_truncate(BlockDriverState *bs, int64_t offset) > +{ > + int ret = 0; > + int64_t image_sectors = offset/BDRV_SECTOR_SIZE; > + int64_t be_offset = cpu_to_be64(offset); > + BDRVAddCowState *state = bs->opaque; > + ret = bdrv_truncate(bs->file, ((image_sectors + 7)>> 3) > + + sizeof(AddCowHeader)); > + if (ret< 0) { > + return ret; > + } > + > + ret = bdrv_pwrite_sync(bs->file, offsetof(AddCowHeader, size), > +&be_offset, sizeof(uint64_t)); > + if (ret< 0) { > + return ret; > + } > + > + ret = bdrv_truncate(state->image_hd, offset); > + return ret; > +} > + > +static QEMUOptionParameter add_cow_create_options[] = { > + { > + .name = BLOCK_OPT_SIZE, > + .type = OPT_SIZE, > + .help = "Virtual disk size" > + }, > + { > + .name = BLOCK_OPT_BACKING_FILE, > + .type = OPT_STRING, > + .help = "File name of a base image" > + }, > + { > + .name = BLOCK_OPT_IMAGE_FILE, > + .type = OPT_STRING, > + .help = "File name of a image file" > + }, > + { NULL } > +}; > + > +static int add_cow_flush(BlockDriverState *bs) > +{ > + BDRVAddCowState *state = bs->opaque; > + int ret = bdrv_flush(state->image_hd); > + if (ret< 0) { > + return ret; > + } > + return bdrv_flush(bs->file); > +} > + > +static BlockDriverAIOCB *add_cow_aio_flush(BlockDriverState *bs, > + BlockDriverCompletionFunc *cb, void *opaque) > +{ > + BDRVAddCowState *state = bs->opaque; > + int ret = bdrv_flush(state->image_hd); > + if (ret< 0) { > + return NULL; > + } > + > + return bdrv_aio_flush(bs->file, cb, opaque); > +} > + > +static BlockDriver bdrv_add_cow = { > + .format_name = "add-cow", > + .instance_size = sizeof(BDRVAddCowState), > + .bdrv_probe = add_cow_probe, > + .bdrv_open = add_cow_open, > + .bdrv_close = add_cow_close, > + .bdrv_create = add_cow_create, > + .bdrv_is_allocated = add_cow_is_allocated, > + > + .bdrv_co_readv = add_cow_co_readv, > + .bdrv_co_writev = add_cow_co_writev, > + .bdrv_truncate = bdrv_add_cow_truncate, > + > + .create_options = add_cow_create_options, > + .bdrv_flush = add_cow_flush, > + .bdrv_aio_flush = add_cow_aio_flush, > +}; > + > +static void bdrv_add_cow_init(void) > +{ > + bdrv_register(&bdrv_add_cow); > +} > + > +block_init(bdrv_add_cow_init); > diff --git a/block_int.h b/block_int.h > index 8c3b863..2b26fdc 100644 > --- a/block_int.h > +++ b/block_int.h > @@ -42,6 +42,7 @@ > #define BLOCK_OPT_TABLE_SIZE "table_size" > #define BLOCK_OPT_PREALLOC "preallocation" > #define BLOCK_OPT_SUBFMT "subformat" > +#define BLOCK_OPT_IMAGE_FILE "image_file" > > typedef struct AIOPool { > void (*cancel)(BlockDriverAIOCB *acb); > diff --git a/docs/specs/add-cow.txt b/docs/specs/add-cow.txt > new file mode 100644 > index 0000000..0443c6c > --- /dev/null > +++ b/docs/specs/add-cow.txt > @@ -0,0 +1,45 @@ > +== General == > + > +Raw file format does not support backing_file and copy on write feature. Then > +you can use add-cow file realize these features. > + > +When using add-cow, procedures may like this: > +(ubuntu.img is a disk image which has been installed OS.) > + 1) Create a raw image with the same size of ubuntu.img > + qemu-img create -f raw test.raw 8G > + 2) Create a add-cow image which will store dirty bitmap > + qemu-img create -f add-cow test.add-cow -o backing_file=ubuntu.img,image_file=test.raw > + 3) Run qemu with add-cow image > + qemu -drive if=virtio,file=test.add-cow > + > +=Specification= > + > +The file format looks like this: > + > + +----------+----------+----------+-----+ > + | Header | Data | Data | ... | > + +----------+----------+----------+-----+ > + > + All numbers in add-cow are stored in Big Endian byte order. > + > + > +== Header == > + > +The Header is included in the first bytes: > + > + Byte 0 - 7: magic > + add-cow magic string ("ADD_COW\xff") > + > + 8 - 11: version > + Version number (only valid value is 1 now) > + > + 12 - 1035: backing_file > + backing_file file name related to add-cow file. While > + using backing_file, must together with image_file. > + > + 1036 - 2059: image_file > + image_file is a raw file, While using image_file, must > + together with image_file. > + > + 2060 - 2067: size > + Virtual disk size of image_file in bytes.
diff --git a/Makefile.objs b/Makefile.objs index c849e51..624c04c 100644 --- a/Makefile.objs +++ b/Makefile.objs @@ -31,6 +31,7 @@ block-obj-$(CONFIG_LINUX_AIO) += linux-aio.o block-nested-y += raw.o cow.o qcow.o vdi.o vmdk.o cloop.o dmg.o bochs.o vpc.o vvfat.o block-nested-y += qcow2.o qcow2-refcount.o qcow2-cluster.o qcow2-snapshot.o qcow2-cache.o +block-nested-y += add-cow.o block-nested-y += qed.o qed-gencb.o qed-l2-cache.o qed-table.o qed-cluster.o block-nested-y += qed-check.o block-nested-y += parallels.o nbd.o blkdebug.o sheepdog.o blkverify.o diff --git a/block.c b/block.c index e865fab..c25241d 100644 --- a/block.c +++ b/block.c @@ -106,7 +106,7 @@ int is_windows_drive(const char *filename) #endif /* check if the path starts with "<protocol>:" */ -static int path_has_protocol(const char *path) +int path_has_protocol(const char *path) { #ifdef _WIN32 if (is_windows_drive(path) || diff --git a/block.h b/block.h index 16bfa0a..8b09f12 100644 --- a/block.h +++ b/block.h @@ -256,6 +256,7 @@ char *bdrv_snapshot_dump(char *buf, int buf_size, QEMUSnapshotInfo *sn); char *get_human_readable_size(char *buf, int buf_size, int64_t size); int path_is_absolute(const char *path); +int path_has_protocol(const char *path); void path_combine(char *dest, int dest_size, const char *base_path, const char *filename); diff --git a/block/add-cow.c b/block/add-cow.c new file mode 100644 index 0000000..d2538a2 --- /dev/null +++ b/block/add-cow.c @@ -0,0 +1,412 @@ +#include "qemu-common.h" +#include "block_int.h" +#include "module.h" + +#define ADD_COW_MAGIC (((uint64_t)'A' << 56) | ((uint64_t)'D' << 48) | \ + ((uint64_t)'D' << 40) | ((uint64_t)'_' << 32) | \ + ((uint64_t)'C' << 24) | ((uint64_t)'O' << 16) | \ + ((uint64_t)'W' << 8) | 0xFF) +#define ADD_COW_VERSION 1 + +typedef struct AddCowHeader { + uint64_t magic; + uint32_t version; + char backing_file[1024]; + char image_file[1024]; + uint64_t size; +} QEMU_PACKED AddCowHeader; + +typedef struct BDRVAddCowState { + char image_file[1024]; + BlockDriverState *image_hd; + uint8_t *bitmap; + uint64_t bitmap_size; +} BDRVAddCowState; + +static int add_cow_probe(const uint8_t *buf, int buf_size, const char *filename) +{ + const AddCowHeader *header = (const void *)buf; + + if (be64_to_cpu(header->magic) == ADD_COW_MAGIC && + be32_to_cpu(header->version) == ADD_COW_VERSION) { + return 100; + } else { + return 0; + } +} + +static int add_cow_open(BlockDriverState *bs, int flags) +{ + AddCowHeader header; + int64_t size; + char image_filename[1024]; + int image_flags; + BlockDriver *image_drv = NULL; + int ret; + BDRVAddCowState *state = (BDRVAddCowState *)(bs->opaque); + + ret = bdrv_pread(bs->file, 0, &header, sizeof(header)); + if (ret != sizeof(header)) { + goto fail; + } + + if (be64_to_cpu(header.magic) != ADD_COW_MAGIC || + be32_to_cpu(header.version) != ADD_COW_VERSION) { + ret = -1; + goto fail; + } + + size = be64_to_cpu(header.size); + bs->total_sectors = size / BDRV_SECTOR_SIZE; + + QEMU_BUILD_BUG_ON(sizeof(state->image_file) != sizeof(header.image_file)); + pstrcpy(bs->backing_file, sizeof(bs->backing_file), + header.backing_file); + pstrcpy(state->image_file, sizeof(state->image_file), + header.image_file); + + state->bitmap_size = ((bs->total_sectors + 7) >> 3); + state->bitmap = g_malloc0(state->bitmap_size); + + ret = bdrv_pread(bs->file, sizeof(header), state->bitmap, + state->bitmap_size); + if (ret != state->bitmap_size) { + goto fail; + } + /* If there is a image_file, must be together with backing_file */ + if (state->image_file[0] != '\0') { + state->image_hd = bdrv_new(""); + /* Relative to image or working dir, need discussion */ + if (path_has_protocol(state->image_file)) { + pstrcpy(image_filename, sizeof(image_filename), + state->image_file); + } else { + path_combine(image_filename, sizeof(image_filename), + bs->filename, state->image_file); + } + + image_drv = bdrv_find_format("raw"); + image_flags = + (flags & (~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING))) | BDRV_O_RDWR; + state->image_hd->keep_read_only = 0; + + ret = bdrv_open(state->image_hd, image_filename, image_flags, + image_drv); + if (ret < 0) { + goto fail; + } + } else { + ret = -ENOENT; + goto fail; + } + return 0; + fail: + if (state->bitmap) { + g_free(state->bitmap); + state->bitmap = NULL; + } + return ret; +} + +static inline void add_cow_set_bit(BlockDriverState *bs, int64_t bitnum) +{ + uint64_t offset = bitnum / 8; + BDRVAddCowState *state = (BDRVAddCowState *)(bs->opaque); + state->bitmap[offset] |= (1 << (bitnum % 8)); +} + +static inline int is_bit_set(BlockDriverState *bs, int64_t bitnum) +{ + BDRVAddCowState *state = (BDRVAddCowState *)(bs->opaque); + uint64_t offset = bitnum / 8; + return !!(state->bitmap[offset] & (1 << (bitnum % 8))); +} + +static int add_cow_is_allocated(BlockDriverState *bs, int64_t sector_num, + int nb_sectors, int *num_same) +{ + int changed; + uint64_t bitmap_size = ((BDRVAddCowState *)(bs->opaque))->bitmap_size; + + /* Beyond the end of bitmap, return error or read from backing_file? */ + if (((sector_num + nb_sectors + 7) / 8) > bitmap_size) { + return 0; + } + + if (nb_sectors == 0) { + *num_same = nb_sectors; + return 0; + } + + changed = is_bit_set(bs, sector_num); + if (changed < 0) { + return 0; + } + + for (*num_same = 1; *num_same < nb_sectors; (*num_same)++) { + if (is_bit_set(bs, sector_num + *num_same) != changed) { + break; + } + } + + return changed; +} + +static int add_cow_update_bitmap(BlockDriverState *bs, int64_t sector_num, + int nb_sectors) +{ + int i, ret = 0; + BDRVAddCowState *state = (BDRVAddCowState *)(bs->opaque); + uint64_t start_pos = sector_num / 8; + uint64_t end_pos = (sector_num + nb_sectors - 1) / 8; + + if (start_pos > state->bitmap_size) { + return -1; + } + + for (i = 0; i < nb_sectors; i++) { + add_cow_set_bit(bs, sector_num + i); + } + ret = bdrv_pwrite_sync(bs->file, + sizeof(AddCowHeader) + start_pos, + state->bitmap + start_pos, + MIN(((end_pos - start_pos) & (~512)) + 512, state->bitmap_size - start_pos)); + return ret; +} + +static void add_cow_close(BlockDriverState *bs) +{ + BDRVAddCowState *state = (BDRVAddCowState *)(bs->opaque); + if (state->bitmap) { + g_free(state->bitmap); + state->bitmap = NULL; + } +} + +static int add_cow_create(const char *filename, QEMUOptionParameter *options) +{ + AddCowHeader header; + int64_t image_sectors = 0; + const char *backing_filename = NULL; + const char *image_filename = NULL; + int ret; + BlockDriverState *bs, *image_bs = NULL; + + while (options && options->name) { + if (!strcmp(options->name, BLOCK_OPT_SIZE)) { + image_sectors = options->value.n / BDRV_SECTOR_SIZE; + } else if (!strcmp(options->name, BLOCK_OPT_BACKING_FILE)) { + backing_filename = options->value.s; + } else if (!strcmp(options->name, BLOCK_OPT_IMAGE_FILE)) { + image_filename = options->value.s; + } + options++; + } + + if (!backing_filename || !image_filename) { + return -EINVAL; + } + /* Make sure image file exists */ + ret = bdrv_file_open(&image_bs, image_filename, BDRV_O_RDWR + | BDRV_O_CACHE_WB); + if (ret < 0) { + return ret; + } + bdrv_close(image_bs); + ret = bdrv_create_file(filename, NULL); + if (ret < 0) { + return ret; + } + + ret = bdrv_file_open(&bs, filename, BDRV_O_RDWR); + if (ret < 0) { + return ret; + } + + memset(&header, 0, sizeof(header)); + header.magic = cpu_to_be64(ADD_COW_MAGIC); + header.version = cpu_to_be32(ADD_COW_VERSION); + pstrcpy(header.backing_file, sizeof(header.backing_file), backing_filename); + pstrcpy(header.image_file, sizeof(header.image_file), image_filename); + header.size = cpu_to_be64(image_sectors * BDRV_SECTOR_SIZE); + + ret = bdrv_pwrite(bs, 0, &header, sizeof(header)); + if (ret < 0) { + bdrv_close(bs); + return ret; + } + bdrv_close(bs); + + BlockDriver *drv = bdrv_find_format("add-cow"); + assert(drv != NULL); + ret = bdrv_open(bs, filename, BDRV_O_RDWR | BDRV_O_NO_FLUSH, drv); + if (ret < 0) { + return ret; + } + + ret = bdrv_truncate(bs, image_sectors * BDRV_SECTOR_SIZE); +fail: + bdrv_close(bs); + return ret; +} + +static int add_cow_co_readv(BlockDriverState *bs, int64_t sector_num, + int remaining_sectors, QEMUIOVector *qiov) +{ + BDRVAddCowState *s = bs->opaque; + int cur_nr_sectors; + uint64_t bytes_done = 0; + QEMUIOVector hd_qiov; + int n, ret = 0; + + qemu_iovec_init(&hd_qiov, qiov->niov); + while (remaining_sectors != 0) { + cur_nr_sectors = remaining_sectors; + if (add_cow_is_allocated(bs, sector_num, cur_nr_sectors, &n)) { + cur_nr_sectors = n; + qemu_iovec_reset(&hd_qiov); + qemu_iovec_copy(&hd_qiov, qiov, bytes_done, + cur_nr_sectors * BDRV_SECTOR_SIZE); + ret = bdrv_co_readv(s->image_hd, sector_num, n, &hd_qiov); + if (ret < 0) { + goto fail; + } + } else { + cur_nr_sectors = n; + if (bs->backing_hd) { + qemu_iovec_reset(&hd_qiov); + qemu_iovec_copy(&hd_qiov, qiov, bytes_done, + cur_nr_sectors * BDRV_SECTOR_SIZE); + ret = bdrv_co_readv(bs->backing_hd, sector_num, + n, &hd_qiov); + if (ret < 0) { + goto fail; + } + } else { + qemu_iovec_reset(&hd_qiov); + qemu_iovec_memset(&hd_qiov, 0, + BDRV_SECTOR_SIZE * cur_nr_sectors); + } + } + remaining_sectors -= cur_nr_sectors; + sector_num += cur_nr_sectors; + bytes_done += cur_nr_sectors * BDRV_SECTOR_SIZE; + } +fail: + qemu_iovec_destroy(&hd_qiov); + return ret; +} + +static int add_cow_co_writev(BlockDriverState *bs, int64_t sector_num, + int remaining_sectors, QEMUIOVector *qiov) +{ + BDRVAddCowState *s = bs->opaque; + int ret = 0; + QEMUIOVector hd_qiov; + qemu_iovec_init(&hd_qiov, qiov->niov); + + qemu_iovec_reset(&hd_qiov); + qemu_iovec_copy(&hd_qiov, qiov, 0, remaining_sectors * BDRV_SECTOR_SIZE); + ret = bdrv_co_writev(s->image_hd, + sector_num, + remaining_sectors, &hd_qiov); + if (ret < 0) { + goto fail; + } + + ret = add_cow_update_bitmap(bs, sector_num, remaining_sectors); + if (ret < 0) { + goto fail; + } +fail: + qemu_iovec_destroy(&hd_qiov); + return ret; +} + +static int bdrv_add_cow_truncate(BlockDriverState *bs, int64_t offset) +{ + int ret = 0; + int64_t image_sectors = offset/BDRV_SECTOR_SIZE; + int64_t be_offset = cpu_to_be64(offset); + BDRVAddCowState *state = bs->opaque; + ret = bdrv_truncate(bs->file, ((image_sectors + 7) >> 3) + + sizeof(AddCowHeader)); + if (ret < 0) { + return ret; + } + + ret = bdrv_pwrite_sync(bs->file, offsetof(AddCowHeader, size), + &be_offset, sizeof(uint64_t)); + if (ret < 0) { + return ret; + } + + ret = bdrv_truncate(state->image_hd, offset); + return ret; +} + +static QEMUOptionParameter add_cow_create_options[] = { + { + .name = BLOCK_OPT_SIZE, + .type = OPT_SIZE, + .help = "Virtual disk size" + }, + { + .name = BLOCK_OPT_BACKING_FILE, + .type = OPT_STRING, + .help = "File name of a base image" + }, + { + .name = BLOCK_OPT_IMAGE_FILE, + .type = OPT_STRING, + .help = "File name of a image file" + }, + { NULL } +}; + +static int add_cow_flush(BlockDriverState *bs) +{ + BDRVAddCowState *state = bs->opaque; + int ret = bdrv_flush(state->image_hd); + if (ret < 0) { + return ret; + } + return bdrv_flush(bs->file); +} + +static BlockDriverAIOCB *add_cow_aio_flush(BlockDriverState *bs, + BlockDriverCompletionFunc *cb, void *opaque) +{ + BDRVAddCowState *state = bs->opaque; + int ret = bdrv_flush(state->image_hd); + if (ret < 0) { + return NULL; + } + + return bdrv_aio_flush(bs->file, cb, opaque); +} + +static BlockDriver bdrv_add_cow = { + .format_name = "add-cow", + .instance_size = sizeof(BDRVAddCowState), + .bdrv_probe = add_cow_probe, + .bdrv_open = add_cow_open, + .bdrv_close = add_cow_close, + .bdrv_create = add_cow_create, + .bdrv_is_allocated = add_cow_is_allocated, + + .bdrv_co_readv = add_cow_co_readv, + .bdrv_co_writev = add_cow_co_writev, + .bdrv_truncate = bdrv_add_cow_truncate, + + .create_options = add_cow_create_options, + .bdrv_flush = add_cow_flush, + .bdrv_aio_flush = add_cow_aio_flush, +}; + +static void bdrv_add_cow_init(void) +{ + bdrv_register(&bdrv_add_cow); +} + +block_init(bdrv_add_cow_init); diff --git a/block_int.h b/block_int.h index 8c3b863..2b26fdc 100644 --- a/block_int.h +++ b/block_int.h @@ -42,6 +42,7 @@ #define BLOCK_OPT_TABLE_SIZE "table_size" #define BLOCK_OPT_PREALLOC "preallocation" #define BLOCK_OPT_SUBFMT "subformat" +#define BLOCK_OPT_IMAGE_FILE "image_file" typedef struct AIOPool { void (*cancel)(BlockDriverAIOCB *acb); diff --git a/docs/specs/add-cow.txt b/docs/specs/add-cow.txt new file mode 100644 index 0000000..0443c6c --- /dev/null +++ b/docs/specs/add-cow.txt @@ -0,0 +1,45 @@ +== General == + +Raw file format does not support backing_file and copy on write feature. Then +you can use add-cow file realize these features. + +When using add-cow, procedures may like this: +(ubuntu.img is a disk image which has been installed OS.) + 1) Create a raw image with the same size of ubuntu.img + qemu-img create -f raw test.raw 8G + 2) Create a add-cow image which will store dirty bitmap + qemu-img create -f add-cow test.add-cow -o backing_file=ubuntu.img,image_file=test.raw + 3) Run qemu with add-cow image + qemu -drive if=virtio,file=test.add-cow + +=Specification= + +The file format looks like this: + + +----------+----------+----------+-----+ + | Header | Data | Data | ... | + +----------+----------+----------+-----+ + + All numbers in add-cow are stored in Big Endian byte order. + + +== Header == + +The Header is included in the first bytes: + + Byte 0 - 7: magic + add-cow magic string ("ADD_COW\xff") + + 8 - 11: version + Version number (only valid value is 1 now) + + 12 - 1035: backing_file + backing_file file name related to add-cow file. While + using backing_file, must together with image_file. + + 1036 - 2059: image_file + image_file is a raw file, While using image_file, must + together with image_file. + + 2060 - 2067: size + Virtual disk size of image_file in bytes.
Add add-cow file format Signed-off-by: Dong Xu Wang <wdongxu@linux.vnet.ibm.com> --- Makefile.objs | 1 + block.c | 2 +- block.h | 1 + block/add-cow.c | 412 ++++++++++++++++++++++++++++++++++++++++++++++++ block_int.h | 1 + docs/specs/add-cow.txt | 45 ++++++ 6 files changed, 461 insertions(+), 1 deletions(-) create mode 100644 block/add-cow.c create mode 100644 docs/specs/add-cow.txt