[sheepdog] [PATCH v4] sheepdog: selectable object size support
Teruaki Ishizaki
ishizaki.teruaki at lab.ntt.co.jp
Tue Feb 10 10:56:33 CET 2015
(2015/02/10 17:58), Liu Yuan wrote:
> On Tue, Feb 10, 2015 at 05:22:02PM +0900, Teruaki Ishizaki wrote:
>> (2015/02/10 12:10), Liu Yuan wrote:
>>> On Tue, Jan 27, 2015 at 05:35:27PM +0900, Teruaki Ishizaki wrote:
>>>> Previously, qemu block driver of sheepdog used hard-coded VDI object size.
>>>> This patch enables users to handle "block_size_shift" value for
>>>> calculating VDI object size.
>>>>
>>>> When you start qemu, you don't need to specify additional command option.
>>>>
>>>> But when you create the VDI which doesn't have default object size
>>>> with qemu-img command, you specify block_size_shift option.
>>>>
>>>> If you want to create a VDI of 8MB(1 << 23) object size,
>>>> you need to specify following command option.
>>>>
>>>> # qemu-img create -o block_size_shift=23 sheepdog:test1 100M
>>>>
>>>> In addition, when you don't specify qemu-img command option,
>>>> a default value of sheepdog cluster is used for creating VDI.
>>>>
>>>> # qemu-img create sheepdog:test2 100M
>>>>
>>>> Signed-off-by: Teruaki Ishizaki <ishizaki.teruaki at lab.ntt.co.jp>
>>>> ---
>>>> V4:
>>>> - Limit a read/write buffer size for creating a preallocated VDI.
>>>> - Replace a parse function for the block_size_shift option.
>>>> - Fix an error message.
>>>>
>>>> V3:
>>>> - Delete the needless operation of buffer.
>>>> - Delete the needless operations of request header.
>>>> for SD_OP_GET_CLUSTER_DEFAULT.
>>>> - Fix coding style problems.
>>>>
>>>> V2:
>>>> - Fix coding style problem (white space).
>>>> - Add members, store_policy and block_size_shift to struct SheepdogVdiReq.
>>>> - Initialize request header to use block_size_shift specified by user.
>>>> ---
>>>> block/sheepdog.c | 138 ++++++++++++++++++++++++++++++++++++++-------
>>>> include/block/block_int.h | 1 +
>>>> 2 files changed, 119 insertions(+), 20 deletions(-)
>>>>
>>>> diff --git a/block/sheepdog.c b/block/sheepdog.c
>>>> index be3176f..a43b947 100644
>>>> --- a/block/sheepdog.c
>>>> +++ b/block/sheepdog.c
>>>> @@ -37,6 +37,7 @@
>>>> #define SD_OP_READ_VDIS 0x15
>>>> #define SD_OP_FLUSH_VDI 0x16
>>>> #define SD_OP_DEL_VDI 0x17
>>>> +#define SD_OP_GET_CLUSTER_DEFAULT 0x18
>>>>
>>>> #define SD_FLAG_CMD_WRITE 0x01
>>>> #define SD_FLAG_CMD_COW 0x02
>>>> @@ -167,7 +168,8 @@ typedef struct SheepdogVdiReq {
>>>> uint32_t base_vdi_id;
>>>> uint8_t copies;
>>>> uint8_t copy_policy;
>>>> - uint8_t reserved[2];
>>>> + uint8_t store_policy;
>>>> + uint8_t block_size_shift;
>>>> uint32_t snapid;
>>>> uint32_t type;
>>>> uint32_t pad[2];
>>>> @@ -186,6 +188,21 @@ typedef struct SheepdogVdiRsp {
>>>> uint32_t pad[5];
>>>> } SheepdogVdiRsp;
>>>>
>>>> +typedef struct SheepdogClusterRsp {
>>>> + uint8_t proto_ver;
>>>> + uint8_t opcode;
>>>> + uint16_t flags;
>>>> + uint32_t epoch;
>>>> + uint32_t id;
>>>> + uint32_t data_length;
>>>> + uint32_t result;
>>>> + uint8_t nr_copies;
>>>> + uint8_t copy_policy;
>>>> + uint8_t block_size_shift;
>>>> + uint8_t __pad1;
>>>> + uint32_t __pad2[6];
>>>> +} SheepdogClusterRsp;
>>>> +
>>>> typedef struct SheepdogInode {
>>>> char name[SD_MAX_VDI_LEN];
>>>> char tag[SD_MAX_VDI_TAG_LEN];
>>>> @@ -1544,6 +1561,7 @@ static int do_sd_create(BDRVSheepdogState *s, uint32_t *vdi_id, int snapshot,
>>>> hdr.vdi_size = s->inode.vdi_size;
>>>> hdr.copy_policy = s->inode.copy_policy;
>>>> hdr.copies = s->inode.nr_copies;
>>>> + hdr.block_size_shift = s->inode.block_size_shift;
>>>>
>>>> ret = do_req(fd, s->aio_context, (SheepdogReq *)&hdr, buf, &wlen, &rlen);
>>>>
>>>> @@ -1569,9 +1587,12 @@ static int do_sd_create(BDRVSheepdogState *s, uint32_t *vdi_id, int snapshot,
>>>> static int sd_prealloc(const char *filename, Error **errp)
>>>> {
>>>> BlockDriverState *bs = NULL;
>>>> + BDRVSheepdogState *base = NULL;
>>>> + unsigned long buf_size;
>>>> uint32_t idx, max_idx;
>>>> + uint32_t object_size;
>>>> int64_t vdi_size;
>>>> - void *buf = g_malloc0(SD_DATA_OBJ_SIZE);
>>>> + void *buf = NULL;
>>>> int ret;
>>>>
>>>> ret = bdrv_open(&bs, filename, NULL, NULL, BDRV_O_RDWR | BDRV_O_PROTOCOL,
>>>> @@ -1585,18 +1606,24 @@ static int sd_prealloc(const char *filename, Error **errp)
>>>> ret = vdi_size;
>>>> goto out;
>>>> }
>>>> - max_idx = DIV_ROUND_UP(vdi_size, SD_DATA_OBJ_SIZE);
>>>> +
>>>> + base = bs->opaque;
>>>> + object_size = (UINT32_C(1) << base->inode.block_size_shift);
>>>> + buf_size = MIN(object_size, SD_DATA_OBJ_SIZE);
>>>> + buf = g_malloc0(buf_size);
>>>> +
>>>> + max_idx = DIV_ROUND_UP(vdi_size, buf_size);
>>>>
>>>> for (idx = 0; idx < max_idx; idx++) {
>>>> /*
>>>> * The created image can be a cloned image, so we need to read
>>>> * a data from the source image.
>>>> */
>>>> - ret = bdrv_pread(bs, idx * SD_DATA_OBJ_SIZE, buf, SD_DATA_OBJ_SIZE);
>>>> + ret = bdrv_pread(bs, idx * buf_size, buf, buf_size);
>>>> if (ret < 0) {
>>>> goto out;
>>>> }
>>>> - ret = bdrv_pwrite(bs, idx * SD_DATA_OBJ_SIZE, buf, SD_DATA_OBJ_SIZE);
>>>> + ret = bdrv_pwrite(bs, idx * buf_size, buf, buf_size);
>>>> if (ret < 0) {
>>>> goto out;
>>>> }
>>>> @@ -1669,6 +1696,21 @@ static int parse_redundancy(BDRVSheepdogState *s, const char *opt)
>>>> return 0;
>>>> }
>>>>
>>>> +static int parse_block_size_shift(BDRVSheepdogState *s, QemuOpts *opt)
>>>> +{
>>>> + struct SheepdogInode *inode = &s->inode;
>>>> + inode->block_size_shift =
>>>> + (uint8_t)qemu_opt_get_number_del(opt, "block_size_shift", 0);
>>>> + if (inode->block_size_shift == 0) {
>>>> + /* block_size_shift is set for cluster default value by sheepdog */
>>>> + return 0;
>>>> + } else if (inode->block_size_shift < 20 || inode->block_size_shift > 31) {
>>>> + return -EINVAL;
>>>> + }
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> static int sd_create(const char *filename, QemuOpts *opts,
>>>> Error **errp)
>>>> {
>>>> @@ -1679,6 +1721,7 @@ static int sd_create(const char *filename, QemuOpts *opts,
>>>> BDRVSheepdogState *s;
>>>> char tag[SD_MAX_VDI_TAG_LEN];
>>>> uint32_t snapid;
>>>> + uint64_t max_vdi_size;
>>>> bool prealloc = false;
>>>>
>>>> s = g_new0(BDRVSheepdogState, 1);
>>>> @@ -1718,9 +1761,10 @@ static int sd_create(const char *filename, QemuOpts *opts,
>>>> }
>>>> }
>>>>
>>>> - if (s->inode.vdi_size > SD_MAX_VDI_SIZE) {
>>>> - error_setg(errp, "too big image size");
>>>> - ret = -EINVAL;
>>>> + ret = parse_block_size_shift(s, opts);
>>>> + if (ret < 0) {
>>>> + error_setg(errp, "Invalid block_size_shift:"
>>>> + " '%s'. please use 20-31", buf);
>>>> goto out;
>>>> }
>>>>
>>>> @@ -1757,6 +1801,47 @@ static int sd_create(const char *filename, QemuOpts *opts,
>>>> }
>>>>
>>>> s->aio_context = qemu_get_aio_context();
>>>> +
>>>> + /* if block_size_shift is not specified, get cluster default value */
>>>> + if (s->inode.block_size_shift == 0) {
>>>
>>> Seems that we don't keep backward compatibility for new QEMU and old sheep that
>>> doesn't support SD_OP_GET_CLUSTER_DEFAULT.
>> Then, I'll add the operation that if block_size_shift from
>> SD_OP_GET_CLUSTER_DEFAULT is zero, block_size_shift is set to 22.
>> Is it OK?
>
> If sheep doesn't support SD_OP_GET_CLUSTER_DEFAULT, sheep will return
> SD_RES_INVALID_PARMS. So to keep backward compatibility, we shouldn't issue
> SD_OP_GET_CLUSTER_DEFAULT to sheep daemon.
OK, I think that the way is better.
>
> My point is that, after user upgrading the sheep and still stick with old QEMU,
> (I guess many users will), any operations in the past sholudn't fail right after
> upgrading.
>
>>
>>>
>>> What will happen if old QEMU with new sheep that support block_size_shift? Most
>>> distributions will ship the old stable qemu that wouldn't be aware of
>>> block_size_shift.
>> If old QEMU with new sheep is used, VDI is created with cluster default
>> block_size_shift and accessed as 4MB object_size.
>> So I think that for backward compatibility, users must do cluster
>> format command with default block_size_shift 22 equal to
>> 4MB object_size.
>
> how old QEMU know about block_size_shift? For old QEMU, block_size_shift is
> encoded as 0 and then send the create request to sheep. Does sheep can handle
> block_size_shift = 0? You know, we can't pass any value to old QEMU for
> block_size_shift.
Sheep can handle block_size_shift = 0, when users create new VDI.
Old QEMU does do_sd_create() without setting hdr.block_size_shift and
sends a request SD_OP_NEW_VDI.
If block_size_shift is set to zero, new sheep sets cluster default value
in cluster_new_vdi() like copies and copy_policy.
Thanks,
Teruaki
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